X-Planes: Martin Marietta X-24

On 5 August 1975 the Martin Marietta X-24B came down the approach at Edwards Air Force Base at something like three hundred miles an hour, descending on the order of ten thousand feet a minute, with no engine running, and landed on the concrete. It was not the first unpowered landing at Edwards. It was the first lifting-body landing on the concrete, where it had to be precise, and the programme’s own account credits it with removing a decision that had already been made about the Space Shuttle. This article is the twenty-fifth in the X-Planes series, following the X-1, the X-2, the X-3, the X-4, the X-5, the X-6, the X-7, the X-8, the X-9, the X-10, the X-11, the X-12, the X-13, the X-14, the X-15, the X-16, the X-17, the X-18, the X-19, the X-20, the X-21, the X-22, and the X-23.

This aircraft and the last one are the same shape and almost nothing else. The X-23 was the unmanned SV-5D, thrown at the Pacific from an Atlas and asked whether a returning vehicle could steer. The X-24A is the piloted SV-5P, air-launched from a B-52 and asked whether a returning vehicle could be landed, as Reed describes both. It is also the vehicle that was refused the designation X-23A in December 1965 and received X-24A in 1967. The previous article is about that paperwork, which Parsch sets out.

The Research Question

Can a pilot land a vehicle with a lift-to-drag ratio of three, without an engine, on a runway, on purpose?

Every part of that sentence is doing work.

Without an engine means the approach is flown once. There is no go-around, no second attempt, and no way to add energy beyond what small landing rockets can give the flare. Whatever the vehicle has when it starts down is nearly all it will ever have.

With a lift-to-drag ratio of three means it descends at roughly eighteen degrees where a transport descends at three. The approach is not a glide in any sense a pilot of the period would have recognised. It is closer to a controlled fall.

On a runway is the part that remained open. The period had been studying the problem since the late 1950s, when it became clear that a returning spacecraft would have to land somehow, from a manned satellite completed with a glide landing in Cheatham 1959 and a power-off landing technique for reentry vehicles in Bray et al 1960, through approaches flown at lift-to-drag ratios of 2 to 4 in Matranga and Armstrong 1959 and Matranga and Menard 1959, to the flare requirements of low lift-to-drag glide vehicles in Faulders et al 1968, approach guidance for unpowered lifting vehicles in Bryson et al 1969, and the CV-990 studies of low lift-to-drag approaches and unpowered automatic landings in Kock et al 1972 and Edwards and Foster 1973. The survey below collects the remainder under approach, flare and automatic landing and under orbiters. Lifting bodies had been landing on the dry lakebed at Edwards since 1963, in Reed, and the longest runway marked on it is more than seven miles long and forgiving in every direction. The main concrete runway is fifteen thousand feet long and three hundred wide, in Edwards Air Force Base.

The programme’s answer, at the very end, was two landings on Edwards main runway by John Manke and Michael Love, and the consequence, by that account, was that the Space Shuttle flew without the air-breathing engines it had been designed to carry for this problem.

The keystone of this article is the landing, and the quantity that makes it hard turns out to be base drag.

Programme Origin

The X-24A was the piloted half of the Martin SV-5 family, whose unpowered entry half the previous article covers. It joined a lifting-body programme already running at the Flight Research Center of the National Aeronautics and Space Administration, or NASA, with the M2 and HL-10 shapes, in Koenig and Brady 1960, Eldredge et al 1965, Smith 1965, Thompson 1966, Kock and Painter 1968, Layton and McTigue 1969, Layton 1970, Manke et al 1970, McTigue 1970, Pyle and Ash 1970, Tang 1970, Kempel et al 1970, Thompson 1970, Dana and Gentry 1970, Kempel and Thompson 1971, Kempel et al 1971, Pyle 1971, Tang 1971, Tang and Pearson 1971, Gentry 1972, Sim 1973, Kempel and Manke 1974, Painter and Sitterle 1974, Kempel et al 1975, Manke and Love 1975, Nagy and Kirsten 1976, Armstrong 1977, Kempel and Painter 1993, Reed et al 1997, Barret 1998. The programme’s narrative history, written by a participant, is Reed’s account of the lifting bodies.

The programme’s logic was that the shape was the hard part and the speed was not. A lifting body’s entry aerodynamics could be measured by throwing small unmanned copies at the atmosphere. The Precision Recovery Including Maneuvering Entry programme, or PRIME, did so, in Reed. Its landing aerodynamics could not, because landing requires a pilot and a pilot requires a vehicle large enough to hold one. So the same shape was built twice at different sizes and asked different questions.

The X-24A flew 28 times between April 1969 and June 1971, reaching Mach 1.6 and 71,400 feet, in the flight log printed by Reed. It was then returned to Martin Marietta and rebuilt. The X-24B that emerged shared the X-24A’s internal structure and almost none of its outer shape, having been given a flat bottom, a double delta planform and a long pointed nose. It flew 36 times between August 1973 and November 1975.

The X-24A was ordered as a single airframe. The Air Force contracted Martin for one SV-5P in May 1966, Martin rolled it out on 11 July 1967, and it reached Edwards on 24 August 1967, according to Reed. NASA joined it to the existing joint programme with the M2-F2 and HL-10 through a memorandum of understanding concluded in October 1967, in Hallion’s history of the Flight Research Center. It then spent February and March 1968 mounted whole in the Ames 40 by 80 foot wind tunnel, a test that Falarski and Mort report and that returns below.

The X-24B began as a recycling proposal. The Air Force Flight Dynamics Laboratory had developed a family of reentry shapes, the FDL-5, 6 and 7, with hypersonic lift-to-drag ratios near 2.5 against 1.2 to 1.4 for the M2, HL-10 and X-24A, and proposed to glove one of them around an existing airframe, as Reed and Hallion both record. NASA transferred 550,000 dollars to the Air Force on 11 March 1971 and the Air Force pledged a similar amount. Air Force Systems Command approved the programme on 21 April 1971, Martin Marietta received the modification contract on 1 January 1972, and a NASA and Air Force memorandum of 4 February 1972 marks the programme’s official start. The rebuild cost 1.1 million dollars against an estimated 5 million for a new vehicle,

\[\frac{1.1}{5.0} = 0.22\]

so the shape was bought for about a fifth of the price of a new aeroplane, and that saving is why the X-24B is a rebuilt X-24A at all.

Getting either of them airborne required a carrier aircraft and a rocket, in Kansas Univ Lawrence 1952, Miele 1955, Cicala and Miele 1956, Miele 1957, Dempster and Bell 1965, Burris and Bender 1969, Ko and Schuster 1983, Ko and Schuster 1984, Whitmore et al 1994.

The Vehicles

The dimensions matter here because the analysis runs on them, and the accessible sources do not agree on them. The figures used here are from the flight-determined table in Saltzman et al 2007, and this article’s aerodynamics are built on that source.

Quantity	X-24A	X-24B
Length	24.50 ft	37.50 ft
Span	13.63 ft	19.14 ft
Reference area	195.0 sq ft	330.5 sq ft
Wetted area	590.0 sq ft	948.4 sq ft
Base area	11.78 to 25.36 sq ft	18.79 to 38.05 sq ft
Weight in the lift and drag tests	6,360 lb	8,500 lb
Aspect ratio	0.953	1.108

The base area is quoted as a range because it was not fixed. The upper flaps that trimmed the vehicle also changed how much of the blunt rear end was exposed, so the drag the vehicle carried depended on how it was trimmed, in Saltzman et al 2002. The next section turns on that dependence.

The narrative histories disagree with the table about how much the rebuild added. Reed puts the X-24B’s growth at 10 feet in span and 14.5 feet in length, and Hallion gives 3 meters and 4.4 meters. The flight-determined table gives

\[\Delta\ell = 37.50 - 24.50 = 13.0\ \text{ft}, \qquad \Delta b = 19.14 - 13.63 = 5.51\ \text{ft}\]

so the length agrees to within about ten percent and the span does not agree at all. The table’s figures are used here because the lift and drag data were reduced against them, and no source consulted here explains the difference in span.

The weights in the table are those of the lift and drag tests, not of the vehicle at launch. Reed gives about 12,000 pounds at launch for the X-24A and 13,800 pounds for the X-24B, a difference of 1,800 pounds, and Cochrane and Graham give the X-24A an empty weight of about 5,500 pounds and about 5,500 pounds of propellants and gases. With $m_p$ the propellant and $m_0$ the launch weight,

\[\frac{m_p}{m_0} = \frac{5{,}500}{12{,}000} = 0.46\]

against the fuel-to-vehicle weight ratio of 0.45 that Reed quotes for the X-24A, 0.35 for the HL-10 and 0.33 for the M2-F3. Both versions flew on the LR-11 rocket engine, rated at 8,480 pounds of vacuum thrust in the X-24A and uprated for the X-24B to 9,800 pounds by raising the chamber pressure and adding nozzle extensions,

\[\frac{T_B}{T_A} = \frac{9{,}800}{8{,}480} = 1.16\]

and this ratio corresponds to the fifteen percent increase in thrust that Reed credits, together with lower drag, for the X-24B’s higher top speed.

Sizing From First Principles

Why a Reentry Vehicle Must Be Cut Off Flat

An aeroplane designed for efficiency ends in a point, because a body that closes smoothly leaves the air behind it at something close to the pressure it started at. A reentry vehicle cannot do that. The heat shield has to terminate somewhere, the rocket engine has to exhaust somewhere, and the structure has to be blunt enough not to melt. The result is a large flat base, and behind that base sits a region of separated flow at less than ambient pressure, pulling backwards. Written as a coefficient on the wetted area, that suction is

\[C_{D_b} = -C_{p_b}\,\frac{A_b}{A_w}\]

with the base pressure coefficient negative, so the term is a positive drag. What follows is a fight with that one expression.

The literature of that penalty is old and large. It begins with base drag and thick trailing edges in Hoerner 1950 and base pressure behind turbulent boundary layers in Chapman 1951, takes in the X-15’s flight base pressures in Saltzman 1961, boattailed afterbodies in Mair 1969 and Payne et al 1980, theory in Tanner 1975, flight tests of fixes for blunt bases in Powers 1988, and the free shear layer account in Roshko 1993. All of it appears below in the cluster on base drag, afterbodies and bluff-body wakes.

Hoerner’s Relation at Full Scale

The base pressure is not independent of the rest of the vehicle, and the correlation used here comes from Hoerner’s compendium of drag data, where most of this subject’s engineering practice still originates. A thicker boundary layer arriving at the base fills the wake and raises the pressure there, so base drag falls as forebody drag rises. Hoerner’s correlation captures that inversely,

\[C_{p_b} = -\frac{K}{\sqrt{C_{D_\text{fore}}}}\]

with the forebody drag referred to the base area. The trouble lies in the coefficient. Hoerner obtained $K = 0.029$ from small-scale model data. Saltzman et al 2007, working from flight measurements on the X-15, the M2-F3 and the Space Shuttle, found that full-scale vehicles require

\[K = 0.090 \ \text{to}\ 0.100\] \[\frac{0.100}{0.029} = 3.4\]

Model-scale data understates the base drag of a real vehicle by a factor of about three and a half.

The article should say why, because the reason is not mysterious. Base pressure is set by the boundary layer arriving at the base, and boundary layers are set by Reynolds number,

\[Re = \frac{V\ell}{\nu}\]

The X-24B on its approach flew at $Re = 9.8\times 10^7$ on its own length. A one-twentieth-scale model in a tunnel at 200 feet per second sits near $2.4\times 10^6$,

\[\frac{Re_\text{flight}}{Re_\text{model}} = 41\]

A factor of forty in Reynolds number is not a small extrapolation, and a correlation calibrated at the bottom of that range should not be expected to hold at the top of it. The general problem of what a model does and does not tell you about an aeroplane is taken up by Reynolds number studies of boattail drag in tunnel and flight in Wilcox and Chamberlin 1974 and Reubush 1976, Effect of Reynolds number on the, of flight base drag reduction in Powers et al 1986, of the tunnel-to-flight Reynolds number gap in Penland and Romeo 1971 and Kilgore and Dress 1984, and of a flight and full-scale tunnel comparison in Fisher and Lanser 1994, and further records sit in the drag cluster below. For a configuration whose base is a substantial fraction of its wetted area, the gap separates a vehicle that lands from one that does not.

The full-scale wind tunnel narrowed that gap without closing it. The X-24A itself was tested in the Ames 40 by 80 foot tunnel at Reynolds numbers from $20.7\times 10^6$ to $41.6\times 10^6$, with most of the data at $32.4\times 10^6$, in Falarski and Mort. In flight the true airspeed $V$ follows from the indicated airspeed $V_i$ and the density ratio $\sigma = \rho/\rho_\text{SL}$, equal to 0.934 at Edwards. At 285 knots indicated, the middle of the final-approach band the pilots flew in Dana and Gentry,

\[V = \frac{V_i}{\sqrt{\sigma}} = \frac{285 \times 1.688}{\sqrt{0.934}} = 498\ \text{ft/s}\]

and on the X-24A’s length of 24.50 feet that gives

\[Re_\text{X-24A} = 7.2\times 10^7, \qquad \frac{7.2\times 10^7}{3.24\times 10^7} = 2.2\]

so the full-scale tunnel sat within a factor of about two of flight, where a small model sits a factor of forty away. The tunnel reported a trimmed maximum lift-to-drag ratio of 4.4 with the gear up, which Pyle and Ash found to overpredict the flight value, although its drag at low lift matched flight more closely for the X-24A than for the M2-F2 and HL-10. Reynolds number was not the only thing separating the tunnel from the aeroplane. Pyle and Ash point to the mounting struts and to the buoyancy of large bulbous shapes in the tunnel, and they record that the lift and drag of these vehicles are extremely sensitive to small changes in contour and in control setting.

The Drag Bucket and a Parameter-Free Factor of Three

Put the two together. The bookkeeping needs one definition used so far without being stated. The equivalent skin-friction coefficient is the minimum drag referred to wetted area rather than to a reference area on which the sources disagree,

\[C_{F_e} = C_{D_\text{min}}\,\frac{S}{A_w}\]

and the forebody drag as Hoerner’s relation wants it, referred to the base area,

\[C_{D_\text{fore},b} = C_{F_e,\text{fore}}\,\frac{A_w}{A_b}\]

Writing both terms as an equivalent skin-friction coefficient referred to wetted area, with $r = A_b/A_w$ the ratio of base area to wetted area and $x$ the forebody contribution, the total is

\[C_{F_e} = x + \frac{k\, r^{3/2}}{\sqrt{x}}\]

where $k$ collects the Hoerner coefficient and a profile factor. The two terms pull in opposite directions, so there is an interior minimum. Differentiating,

\[\frac{dC_{F_e}}{dx} = 1 - \frac{k\,r^{3/2}}{2x^{3/2}} = 0 \quad \Longrightarrow \quad k\,r^{3/2} = 2x^{3/2}\]

which locates the optimum,

\[x_\text{opt} = \left(\frac{k}{2}\right)^{2/3} r\]

and substituting that back into the total gives something remarkable,

\[C_{F_e} = x + \frac{2x^{3/2}}{\sqrt{x}} = x + 2x = 3x\]

At the optimum the total drag is exactly three times the forebody drag, and the base contributes exactly twice it. The result contains no Hoerner coefficient, no profile factor and no area ratio. It follows from the form of the trade alone and describes no vehicle in particular.

The source’s two coefficients, in Saltzman et al 2007, provide the check. It quotes the optimal forebody value as $0.1284\,r$ and the resulting minimum total as $0.3852\,r$, and

\[\frac{0.3852}{0.1284} = 3.000\]

This article uses the source’s absolute coefficients rather than its own. The factor of three is parameter-free and is derived above, but the absolute value depends on how the base pressure profile factor is applied, and the arrangement used here gives

\[\left(\frac{0.10/0.92}{2}\right)^{2/3} = 0.1435\]

where the source gives 0.1284, a difference of twelve percent. The structure is derived and the numbers are flight-anchored.

What That Costs

Maximum lift-to-drag ratio for a given parasite drag and aspect ratio is standard,

\[\left(\frac{L}{D}\right)_\text{max} = \frac{1}{2}\sqrt{\frac{\pi e A}{C_{D_0}}}\]

and something useful happens when the drag is expressed on wetted area. Substituting $C_{D_0} = C_{F_e} A_w/S$ and $A = b^2/S$, the reference area cancels completely,

\[\left(\frac{L}{D}\right)_\text{max} = \frac{1}{2}\sqrt{\frac{\pi e\, b^2}{A_w\, C_{F_e}}}\]

The right independent variable for this class of vehicle is therefore span squared over wetted area, a quantity Saltzman et al 2007 call the wetted aspect ratio,

\[A = \frac{b^2}{S}, \qquad A_\text{wetted} = \frac{b^2}{A_w}\]

It removes the argument about what the reference area should be, which for a shape with no wing is not obvious.

Evaluating at the drag bucket, with an efficiency factor of 0.6,

Vehicle	$b^2/A_w$	Lift-to-drag ratio, clean base	Lift-to-drag ratio, full base
M2-F1	0.466	2.82	2.82
M2-F2	0.216	2.32	2.32
HL-10	0.402	3.91	2.79
X-24A	0.315	4.39	2.99
X-24B	0.386	4.88	3.43
X-15	0.422	4.31	4.31
Shuttle prototype	0.515	4.07	4.07

Three, near enough, for a vehicle whose shape was chosen to survive Mach 25.

A Check the Model Was Not Fitted To

The Space Shuttle prototype Enterprise flew in two configurations during its approach and landing tests, truncated and with a tailcone fitted over the blunt base, in Saltzman et al 2007. The same airframe flew with and without the penalty, as close to a controlled experiment as this subject offers.

With the tailcone the base drag is gone and only the forebody term survives, so the prediction is the same expression evaluated at $0.1284\,r$ rather than $0.3852\,r$. Since the ratio of those is three and the lift-to-drag ratio goes as the inverse square root of the drag,

\[\frac{(L/D)_\text{tailcone}}{(L/D)_\text{truncated}} = \sqrt{3} = 1.73\] \[\left(\frac{L}{D}\right)_\text{tailcone} = 7.05\]

against the measured 7.5 that the same authors report, an error of six percent. Nothing in that prediction was fitted to the Enterprise. It comes from the vehicle’s span, its wetted area, its base area, and a factor of three derived from a differentiation.

Covering the base is worth a factor of the square root of three in lift-to-drag ratio. The factor is the price of being a reentry vehicle, stated as cleanly as this subject allows.

Dependent Systems

The Approach, Flown Fast and Steep on Purpose

The remaining analysis runs off one relation used above but not yet displayed, the parabolic drag polar,

\[C_D = C_{D_0} + k_i C_L^2, \qquad k_i = \frac{1}{\pi e A} = 0.479\]

The second term is the drag that lift costs, and for a shape of aspect ratio near one it is neither small nor well described by the classical elliptic result, in Sibert 1943, Polhamus 1953, Graham et al 1954, Nonweiler 1960, Osborne and Kelly 1960, Frost and Rutherford 1963, Sanders 1965, Gardner and Weir 1966, Henderson 1966, Lundry 1967, Polhamus 1968, Ward 1968, Loth and Boyle 1969, Snyder and Zumwalt 1969, Hancock 1972, Yajnik and Subbaiah 1976, Haftka 1977, Lundry 1977, Laitone 1978, Deyoung 1980, Sachs 1980, Axelson and Hill 1981, Knaus 1983, Lottati 1984, Stark 1985, Greene 1988, Cole and Malmuth 1989, Greene 1989, McCutchen 1989.

It is used together with the lift balance that fixes the lift coefficient at any given speed,

\[C_L = \frac{W}{q S}, \qquad q = \tfrac{1}{2}\rho V^2\]

The best glide condition is where the two drag terms are equal,

\[C_L^* = \sqrt{\frac{C_{D_0}}{k_i}} = 0.304, \qquad \left(\frac{L}{D}\right)_\text{max} = \frac{1}{2\sqrt{C_{D_0} k_i}} = 3.43\]

and the glide angle follows directly from the ratio,

\[\gamma^* = \arctan\frac{1}{(L/D)_\text{max}} = 16.2^\circ\]

At that condition the speed, from the ordinary lift balance, is

\[V^* = \sqrt{\frac{2W}{\rho S C_L^*}} = 276\ \text{ft/s} = 188\ \text{mph}\]

using the density at 2,302 feet, taken here for Edwards, whose airfield elevation is given as 704 metres, or 2,311 feet, in Edwards Air Force Base. Every altitude and every dynamic pressure in this article comes from a tabulated atmosphere rather than from a measurement, and producing that tabulation was a large twentieth-century engineering effort, in Webster 1947, Standard Atmosphere - Tables 1955, Sterne 1958, Pisharoty 1959, Air Force Test Pilot School Edwards Afb Ca 1962, U.S. Standard Atmosphere, 1962, U.S. Standard Atmosphere Supplements 1966, U.S. Standard Atmosphere Suppleme, Minzner 1967, Ghosh 1970, Minzner et al 1976, Peters 1977, Blish 1980, Dennis P. Dykstra 1980, Price and Blanchard 1981, Zuppardo 1993. The lifting bodies did not approach at 188 miles an hour, in Dana and Gentry. This analysis takes 300 for the X-24B.

That is sixty percent faster than its best glide,

\[\frac{V}{V^*} = 1.60\]

and flying faster than best glide makes the glide angle steeper, not shallower. The polar explains it. Lift coefficient falls as the inverse square of speed, so at 1.60 times the best-glide speed it drops to

\[\frac{C_L}{C_L^*} = \left(\frac{V}{V^*}\right)^{-2} = 0.39\]

which lands at $C_L = 0.12$. At that lift coefficient the induced term has almost vanished and the parasite term has not,

\[\frac{k_i C_L^2}{C_D} = 0.13\]

so seven eighths of the drag is now the base and the skin, being paid for at a dynamic pressure of 215 pounds per square foot. The lift-to-drag ratio falls to 2.34, and

\[\gamma = \arctan\frac{1}{2.34} = 23.2^\circ\] \[\dot h = V\sin\gamma = 173\ \text{ft/s} = 10{,}400\ \text{ft/min}\]

A transport on a three-degree approach at 140 knots descends at

\[\dot h = 140 \times 1.688 \times \sin 3^\circ \times 60 = 742\ \text{ft/min}\] \[\frac{10{,}400}{742} = 14\]

Ten thousand four hundred feet per minute, fourteen times a transport aircraft’s approach. The next section explains why the approach was deliberately made worse.

The fast, steep approach is documented practice, and the documented speeds are higher still. Dana and Gentry, two of the programme’s pilots, describe the pattern the lifting bodies inherited from the X-15. A circling approach through 180 degrees begins at 20,000 feet, and a final approach is held at 270 to 300 knots indicated airspeed down to 1,000 feet, where the flare begins. By the relation between indicated and true airspeed given above, with $1/\sqrt{0.934} = 1.035$, that band is 279 to 310 knots true at Edwards, or 321 to 357 miles an hour, which is

\[\frac{321}{188} = 1.71 \quad \text{to} \quad \frac{357}{188} = 1.90\]

times the best-glide speed derived above. The 300 miles an hour used in this section therefore sits below the documented band rather than above it, and the X-24B’s final-approach speed is given in none of the reports examined.

Gentry gives the reason for the steep approach in a pilot’s terms. A shallow, slow approach would leave very little float after the flare in which to adjust the sink rate, while a steep, fast one stores energy for the flare to spend, provides ample load factor for the flare itself, and is aimed like a dive-bombing run, at path angles of 10 to 25 degrees. He adds that the lifting-body pilots flew on the high-speed side of the lift-to-drag curve, so that diving and pulling up moved the aim point in the instinctive direction, and that speed brakes, which on the X-24A are the upper flaps, can be used like engines while weighing little and burning nothing.

The Flare

The vehicle arrives at the ground with a great deal of speed and a sink rate that would destroy it. The flare is the manoeuvre that converts one into the other, and the landing problem is concentrated there, in Pasek and Shanahan 1954, Matranga 1961, Gannett and McLean 1964, Addy 1970, Rubin 1971, Ohta and Sugiura 1973, Leland and Thompson 1975, Palmer and Petitt 1977, Heffley and Schulman 1981, Nadkarni 1981, Walker 1981, Watson et al 1983, Chang and Muirhead 1987, Hynes et al 1988.

Treating the flare as an arc that rotates the flight path from $-\gamma$ to zero at load factor $n$, the instantaneous radius is

\[R = \frac{V^2}{g(n-1)}\]

That radius is not constant, and assuming it is gets the answer wrong. The vehicle decelerates through the manoeuvre, so the arc tightens as it goes. Evaluating the radius once at the entry speed makes the path too long. That overstates the work done against drag and so understates the touchdown speed. The error is nine percent in height and twelve percent in speed at moderate load factor, and at low load factor it is qualitative. The flare below is therefore integrated rather than assumed circular. Stepping in path angle, with $s$ the distance along the path, the system is

\[\frac{ds}{d\gamma} = -R = -\frac{V^2}{g(n-1)}\] \[\frac{dh}{ds} = \sin\gamma, \qquad \frac{dx}{ds} = \cos\gamma\] \[\frac{dV}{ds} = \frac{W\sin\gamma - D}{mV}\]

with the drag evaluated at the instantaneous speed and at the lift coefficient the load factor demands,

\[C_L = \frac{nW}{qS}, \qquad D = qS\left(C_{D_0} + k_i C_L^2\right)\]

Three equations and a polar. The first makes the arc tighten, because $R$ carries $V^2$ and $V$ is falling throughout.

The load factor is not assumed either. It is defined by

\[n = \frac{L}{W}\]

and it is bounded by structure and by the pilot as well as by aerodynamics, in Effect of Variations in weight or Normal Acceleration on the Ceiling of Jet-Propelled Aircraft, Correspondence 1955, Sutcliffe 1955, Mayer and Hamer 1961, White 1971, Anderson et al 1973, Keskar and Slater 1979, Thornton 1993. The touchdown speed is quoted, so the load factor can be solved for, which converts a guess into a statement about what was flown. Integrating the system above and adjusting $n$ until the vehicle reaches the runway at 200 miles an hour gives

\[n = 1.19, \qquad h_\text{flare} = 2{,}163\ \text{ft}, \qquad t = 21.9\ \text{s}\]

Two thousand one hundred and sixty feet, and twenty-two seconds. Taking a transport aircraft’s flare to begin at about thirty feet and to last about three seconds,

\[\frac{2{,}163}{30} = 72, \qquad \frac{21.9}{3} = 7.3\]

In this model the X-24B begins its flare seventy times higher and stays in it seven times longer. The arc is 9,616 feet and its horizontal projection is 9,306, so during the flare the vehicle covers

\[\frac{9{,}306}{15{,}000} = 0.62\]

of the length of the concrete runway it is aiming at. The manoeuvre is longer than most of the runway.

The lift coefficient the flare demands is modest, and a check gives

\[C_L = \frac{nW}{qS} = 1.19 \times 0.120 = 0.142\]

against a maximum usable value near 0.7, so the vehicle is nowhere near stall when the flare begins. Only at the very end does it come near, and the next section takes up that end.

The Flare Has a Corridor

The obvious way to touch down slower is to pull less, and that does work, but only within a band.

Load factor	Flare begins at	Arc	Time	Touchdown speed
1.05 g	6,780 ft	25,989 ft	59.1 s	47 mph
1.10 g	3,804 ft	15,985 ft	36.3 s	154 mph
1.19 g	2,163 ft	9,616 ft	21.9 s	199 mph
1.30 g	1,425 ft	6,520 ft	14.8 s	222 mph
1.50 g	880 ft	4,124 ft	9.4 s	241 mph
2.00 g	449 ft	2,141 ft	4.9 s	256 mph
3.00 g	224 ft	1,073 ft	2.4 s	260 mph

The band is bounded from both ends and neither bound is a matter of comfort.

At the top, pulling harder gains almost nothing,

\[V_\text{td}(3g) - V_\text{td}(2g) = 260 - 256 = 4\ \text{mph}\]

because a tighter arc is a shorter arc and spends less energy against drag. The vehicle arrives fast however hard it is pulled.

At the bottom, a gentle flare is a very long one. At 1.10 g the arc is nearly 16,000 feet and takes 36 seconds, and by 1.05 g the vehicle has decayed to 47 miles an hour, far below any speed at which this shape flies. The maximum usable lift coefficient is also an assumption, and a contested one for this class of shape, since a lifting body does not stall in the way a wing does, in Graham and Luskin 1946, Nonweiler 1955, The Pursuit of Maximum Lift 1955, Vidal et al 1961, Conner et al 1965, Lusty and Miele 1966, Maikapar 1966, Wootton 1967, Huang 1968, Miele and Damoulakis 1969, Pritchard 1969, Bridson and Hancock 1970, Liebeck and Ormsbee 1970, Thompson and Hull 1970, Ormsbee and Chen 1972, Bihrle and Bowman 1981, Lapygin and Tret’yakov 1986, Deese and Agarwal 1990. Taking a value of 0.7, the stall speed is

\[V_\text{stall} = \sqrt{\frac{2W}{\rho S C_{L_\text{max}}}} = 124\ \text{mph}\]

and the flare reaches it at about 1.07 g. At the solved 1.19 g the margin is

\[\frac{V_\text{td}}{V_\text{stall}} = \frac{199}{124} = 1.60\]

The usable corridor is therefore roughly 1.07 g to 1.5 g, about four tenths of a g wide, with stalling short of the runway at one end and arriving at 240 miles an hour at the other.

That corridor is not this article’s invention. Walker 1981 describes it when it speaks of boundaries between marginal and routine and of an optimal preflare condition at the centre of them, and it states explicitly that those boundaries rest on judgements formed from X-15 and lifting-body experience.

The Flare as the Pilots Flew It

The pilots did not fly the flare all the way to the ground. The technique Dana and Gentry describe begins a flare of about 1.5 g at 1,000 feet above the ground and brings the vehicle to level flight at 100 feet, at 220 to 240 knots indicated airspeed. The gear goes down there, a gradual descent follows, and indicated touchdown speeds ranged from 155 to 223 knots. The flare and the touchdown are two manoeuvres with a float between them.

The integrated flare above can be held against that description. At 1.5 g from the 300 miles an hour assumed here it begins at 880 feet and exits at 241 miles an hour, while the documented flare spans

\[h_\text{flare} = 1{,}000 - 100 = 900\ \text{ft}\]

so at the documented load factor the model’s flare height agrees with the documented one to about two percent. The float then spends what the flare leaves. Holding level flight at one g, the speed decays at the rate the drag polar sets,

\[\frac{dV}{ds} = -\frac{g}{V\,(L/D)}, \qquad s_\text{float} = \frac{1}{g}\int_{V_\text{td}}^{V_1} V\,\frac{L}{D}\,dV + h_1\,\overline{\left(\frac{L}{D}\right)}\]

where $V_1$ is the speed at the end of the flare, $h_1 = 100$ feet is the height of the level-off, $L/D$ is evaluated at one g and at each speed, and the overbar denotes its mean over the float. From 241 to 200 miles an hour this gives

\[s_\text{float} = 2{,}303\ \text{ft}, \qquad \overline{L/D} = 3.25, \qquad t \approx 7.1\ \text{s}\]

Read this way, the 1.19 g solved above is the load factor a flare would need if it ended on the runway, and the record shows the flare did not end there. The documented technique flares at the top of the corridor derived above and uses the float to bleed off the excess speed, the margin for error Gentry describes. The available sources do not say how closely the X-24B’s concrete landings followed this pattern, since the pattern was written down in 1970 about the M2-F3, the HL-10 and the X-24A.

What the Landing Gear Sees

One number a landing-gear engineer would ask for first has not yet appeared, the sink rate at the moment of contact.

In this model the flare drives the path angle to zero, so the sink rate goes to zero with it and the meaningful way to report it is at a small residual angle. Integrating the same system and stopping short,

\[\dot h = V\sin\gamma_\text{residual}\]

Residual path angle	Speed	Sink rate
2.0 degrees	211 mph	10.8 ft/s
1.0 degrees	205 mph	5.3 ft/s
0.5 degrees	202 mph	2.6 ft/s

Designing a gear to absorb that, and knowing what it will see in service, has a long literature, from the effect of wing lift on gear loads in Lindquist 1952 and the X-15’s landing loads in Kordes and McKay 1962 to the dynamics of tricycle gear in McKay and Noll 1967, damping at touchdown in Venkatesan and Krishnan 1975, drop testing in Daughetee 1974 and the Langley gear dynamics programme in McComb and Tanner 1988. More of it is listed below under landing gear, touchdown and landing loads.

A transport aeroplane’s landing gear is designed for a limit descent velocity of 10 feet per second, in 14 CFR 25.473. The X-24B therefore had to arrive within about two degrees of level to stay inside that design case, and within about half a degree to touch down at a quarter of it. That is the precision the corridor is about, and it is a tighter statement of the problem than the touchdown speed alone.

The flight record does not contain the number this section computes. Larson analysed 81 lifting-body landings, 25 of them by the X-24A, and states that vertical velocity at touchdown is not presented because the vehicles carried no instrumentation for it. What was recorded is the peak normal acceleration at the centre of gravity during ground impact, which ranged from 1.15 to 2.37 g with a mean of 1.53 g across the three vehicles. For the X-24A alone, the 25 values in Larson’s table give a mean of

\[\bar n_\text{impact} = \frac{1}{N}\sum_{i=1}^{N} n_i = 1.43, \qquad N = 25\]

within a range of 1.19 to 1.69 g, and its true airspeed at touchdown averages 184 knots, or 212 miles an hour, between 165 and 208 knots, which is consistent with the 200 miles an hour used above. An impact load factor is not a sink rate, and converting one into the other needs the stroke and stiffness of the gear, which the sources at hand do not give.

The gear brought one of the landing’s most undesirable characteristics. It was extended just before touchdown, pneumatically in slightly more than a second, so that the lift-to-drag ratio stayed high until the last moment, as Dana and Gentry describe. Its extension produced a substantial nose-down pitching moment on the M2-F2, M2-F3 and X-24A that Manke, Retelle and Kempel call unsatisfactory, and the full-scale tunnel measured why. With the gear down the X-24A’s trimmed maximum lift-to-drag ratio fell by 0.8 to 1.8 depending on the upper-flap setting, and holding a constant lift coefficient through the extension needed 7 to 10 degrees of additional longitudinal control, in Falarski and Mort. For the X-24B, Reed reports that the main gear sat well aft of the centre of gravity, so that a nose-low slap-down was expected, that tyre tread separated from the casing in dynamic load tests, and that a newly shaved set of tyres was therefore fitted for every flight.

Energy, Spent Exactly Once

The reason none of this can be retried can be made quantitative. Expressing the vehicle’s total energy at the start of the flare as an equivalent height,

\[h_E = h + \frac{V^2}{2g} = 2{,}163 + 3{,}009 = 5{,}172\ \text{ft}\]

At touchdown the vehicle has no height left and only its speed, so

\[h_{E,\text{td}} = \frac{V_\text{td}^2}{2g} = 1{,}322\ \text{ft}\] \[\frac{5{,}172 - 1{,}322}{5{,}172} = 0.74\]

Seventy-four percent of the vehicle’s remaining energy is spent in the flare. Multiplying a constant approach drag along the whole arc would overstate that share, because the drag falls with the speed. The difference of energy heights needs no such assumption. The mean deceleration along the arc is

\[\bar a = \frac{V_i^2 - V_f^2}{2 s} = 0.18\,g\]

The literature of managing that quantity is Gerdes and Hynes 1971, Hardy 1972, Sederstrom et al 1973, Crane et al 1974, Bull 1976, Hawthorne 1976, Hawthorne 1976, Hawthorne 1976, Kraiss and Baty 1978, Halyo 1983, Day 2004.

Making It Flyable

A shape with an aspect ratio near one and no tail to speak of is not naturally stable, and the lifting bodies were flown with stability augmentation from the beginning, as Kotfila and Painter 1969 and Painter and Sitterle 1974 record, against a general literature of augmentation such as O’hara 1971, Johnson and Weir 1969 and Painter and Sitterle 1972. Whether a pilot could work with the result is a separate question from whether the vehicle was stable, and it has a separate literature and vocabulary, surveyed in Ashkenas 1984 and Harper and Cooper 1986 and applied to lifting reentry vehicles in terminal flight in DiFranco 1971. Both literatures have clusters in the survey, one for flight control and one for handling qualities.

Where the Drag Numbers Come From

The analysis above uses drag coefficients obtained in flight rather than in a tunnel. For this class of vehicle flight data are a necessity, as the reviews of flight-to-tunnel drag correlation in Saltzman and Ayers 1981 and Saltzman and Ayers 1982 and the tunnel and flight comparisons in Daforno 1982 and Springer 1998 show. Extracting a lift and drag polar from a flight is a specialised discipline, since neither quantity is measured directly and both have to be reconstructed from accelerations, in Bellman 1959, Gilyard 1972, Macwilkinson et al 1974, Macwilkinson et al 1974, Hicks and Huckabine 1989, Saltzman et al 1999 and Saltzman et al 2002. The lift side is equally awkward, since a body that generates lift without a wing does not obey the ordinary low-aspect-ratio relations, which are set out in Lawrence 1951, Lawrence 1953, Tsien 1957, Sugai 1965 and Laitone 1989.

What the Reshaping Bought

The X-24B was the X-24A’s structure under a new outer shape, in Reed, so the two form a controlled comparison.

\[\left(\frac{L}{D}\right)_\text{X-24A} = 2.99, \qquad \left(\frac{L}{D}\right)_\text{X-24B} = 3.43, \qquad \text{ratio} = 1.15\]

Almost all of that came from span rather than from a cleaner base. The wetted aspect ratio rose by a factor of 1.23 while the base-to-wetted ratio barely moved, at 0.93 of its former value, and since the lift-to-drag ratio goes as the square root of the wetted aspect ratio,

\[\sqrt{1.23} = 1.11\]

accounting for most of the 1.15 observed. The long pointed nose delivered span-loading, not base cleanliness, the opposite of what the shape suggests at a glance.

How Far It Could Reach

A glide at a fixed lift-to-drag ratio reaches a radius proportional to the height it starts from,

\[r = h\,\frac{L}{D}\]

which for the X-24B from 20,000 feet is 13 miles, and from 40,000 feet is 26. The performance of a glide considered as a range problem is Bell 1964, Knapp and Barton 1968, Sleeman 1971, Kelley et al 1982. Those radii are the entire manoeuvring room available, and inside them the vehicle must arrive at a runway threshold at a particular speed on a particular heading, having spent the approach unable to add more energy than its small landing rockets could supply.

The Flight Test Record

	X-24A	X-24B
First flight	17 April 1969, unpowered	1 August 1973, unpowered
First powered flight	19 March 1970	15 November 1973
Flights	28	36
Powered and glide flights	18 and 10	24 and 12
Maximum speed	Mach 1.60, 1,036 mph, 29 March 1971	Mach 1.752, 1,164 mph, 25 October 1974
Maximum altitude	71,400 ft, 27 October 1970	74,100 ft, 22 May 1975
Last flight	4 June 1971	26 November 1975

The figures in the table are from the flight log compiled by Jack Kolf and printed in Reed, which draws on Hallion. The narrative accounts differ from the log in three places. Hallion’s text dates the X-24B’s fastest flight to 24 October 1974 at Mach 1.76 where the log gives 25 October at Mach 1.752, and it dates the last powered flight to 9 September 1975 where the log lists a further powered flight by Bill Dana on 23 September. Hallion also describes nine more glides after the X-24A’s first before its first powered flight, where the log lists nine glides in all up to that point and a tenth, Cecil Powell’s first flight, in February 1971. The counts in the table are the log’s.

The two concrete-runway landings came at the end and were the point. Every earlier lifting-body landing had been on the dry lakebeds at Edwards, almost all of them on Rogers Dry Lake, with an emergency landing on Rosamond Dry Lake after an engine failure among the 81 that Larson analyses. The HL-10’s powered approaches needed a runway 7.5 miles long, which Kock and Fulton say only Rogers Dry Lake offered, against the 15,000 feet of the Edwards concrete given by Reed,

\[\frac{7.5 \times 5{,}280}{15{,}000} = \frac{39{,}600}{15{,}000} = 2.6\]

a factor of 2.6 in the margin available for an error.

The programme record and the vehicles it sat among are in Thompson 1966, Layton and McTigue 1969, McTigue 1970, Layton 1970, Manke and Love 1975, Armstrong 1977, Kempel and Painter 1993 and Reed et al 1997, with more in the survey’s X-24 and lifting-body cluster. The wider body of flight research the period produced around them fills the flight test and handling qualities clusters.

The X-24A Glide Flights

The X-24A’s first flight came nearly two years after its rollout. Ground tests found that runaway control-surface oscillations fed back through soft actuator mounts in an aft structure so light that 140 pounds of ballast had to be added to balance the vehicle, and the structure was stiffened, in Reed. The first glide, on 17 April 1969, came close to ending the programme. Jerauld Gentry launched with the upper flaps set 21 degrees open for the lowest subsonic drag, so that all roll control came from the lower flaps. One minute into the flight the automatic rudder-to-aileron interconnect failed and stuck, and on the approach at 300 knots and two degrees angle of attack a lateral-directional oscillation developed. Gentry slowed to 270 knots and lit the landing rockets, and just before touchdown the lower flaps reached their rate limit and the roll rate reached 20 degrees per second. The second glide repeated the rate limiting with the interconnect working.

The cause was a derivative with the wrong sign. In Robert Hoey’s account, quoted by Reed, the wind tunnel had predicted the yawing moment due to aileron for the lower flap with the opposite sign to flight, an error attributed to interference from the model’s sting when the flaps were nearly closed, and later analysis put the first approach well inside the predicted region of pilot-induced oscillation. Manke, Retelle and Kempel cite the same derivative, opposite in sign to the tunnel data in some flight regions, as a warning for any vehicle that relies on an interconnect to cancel adverse yaw. Before the third glide the lower-flap actuators were reworked to roughly twice their surface rate, and the interconnect schedule, the stick forces and the damper gains were changed. The table in Larson records the landing rockets in use on X-24A flights 1, 2, 3 and 14, and lateral misses of 208 and 100 feet on flights 2 and 4, both marked as control problems on the final approach.

The X-24A Powered Flights

The X-24A made 18 powered flights between 19 March 1970 and 4 June 1971, each lasting just under eight minutes, two and a half under rocket power followed by a glide of five, in Reed. The first five missed their primary objectives through system failures after launch. After the first, 140 pounds of tail ballast came out and the upper flaps were biased from 30 to 35 degrees and later to 40, opening the shuttlecock for directional stability. Manke passed Mach 1 on 14 October 1970, reaching Mach 1.19 at 67,900 feet, flew a simulated Space Shuttle approach and landing from 71,400 feet less than two weeks later, and reached Mach 1.60 on 29 March 1971. One flight ended with a premature engine shutdown and a small fire in the engine bay, and the damage kept the vehicle on the ground for nearly two months, in Hallion. The last flight lit only two of the engine’s four chambers and stayed subsonic.

Two findings from the powered flights mattered beyond the vehicle. The first is a nose-up trim change under thrust. Manke, Retelle and Kempel compute that it would need a misalignment of about 7 inches between the thrust line and the centre of gravity, against less than 2 inches measured, and attribute it provisionally to the exhaust plume, deflected upward in a rooster tail. Hallion records that the Flight Research Center warned the Shuttle’s designers about it, because a trim change of that kind could impose unacceptable loads on an orbiter during boost. The second is that the X-24A flew repeatedly beyond the boundary at which its body-axis directional stability parameter becomes negative, with no perceptible change in its behaviour, which showed that a lifting body can be flown there because its large dihedral effect supplies the effective directional stability. The same paper reports controllability problems near Mach 0.96 at low angle of attack that the tunnel data had not predicted, and judges the X-24A’s subsonic handling, after the control changes, as good as the HL-10’s and better in pitch during approach and landing.

The X-24A never flew its maximum-speed profile. Hoey, quoted by Reed, reports that the simulation predicted about Mach 1.7 for an optimum full-duration burn, that both attempts at it ended in engine malfunctions, and that with the X-24B already approved the team judged another tenth of a Mach number not worth the risk to the vehicle and its pilot.

How Close the X-24A Landed

The X-24A’s landings are the best-measured part of its record. Larson tabulates each of its first 25, with the distance from an intended touchdown point measured by surveyor’s wheel. From flight 16 of the HL-10 onward, and on every X-24A flight, the pilot was told to touch down as close as possible to a particular runway marker. Leaving out the two approaches marked as control problems, 20 of the X-24A landings have a measured longitudinal miss $x_i$, positive when long, and their signed mean, mean absolute value and standard deviation are

\[\bar x = \frac{1}{N}\sum_{i=1}^{N} x_i = 1{,}125\ \text{ft}, \qquad \overline{|x|} = 1{,}450\ \text{ft}, \qquad s_x = \sqrt{\frac{\sum (x_i - \bar x)^2}{N-1}} = 1{,}678\ \text{ft}\]

with $N = 20$, the extremes at 1,115 feet short and 4,185 feet long, and 7 of the 20 within 500 feet of the mark. Across all three vehicles Larson fits a normal distribution with a mean of 112 feet short and a standard deviation of 1,793.6 feet.

The small averages quoted elsewhere are signed means. Gentry reports an average miss of less than 250 feet on about 30 flights, and Hallion an average longitudinal miss of 76 meters for the X-24A on lakebed runway 18. A signed mean lets long and short landings cancel, and Larson’s three-vehicle mean of 112 feet sits inside those figures while the scatter about it is about a third of a mile. The X-24A subset of Larson’s table has a signed mean of 1,125 feet long, which Hallion’s 76 meters does not match, and the record available here does not show which flights Hallion averaged.

Rebuilding the X-24A as the X-24B

The X-24B kept the X-24A’s systems and changed almost everything that met the air. Reed describes the new shell as a 78 degree double delta for centre-of-gravity control, with a boat-tail for subsonic lift-to-drag ratio, a flat bottom and a 3 degree nose ramp for hypersonic trim. Two outboard ailerons joined the X-24A’s eight control surfaces and took over roll control from the split flaps, a modified Grumman F11F nose gear brought nosewheel steering, an F-104 stick shaker warned at 16 degrees angle of attack, and the triply redundant rate dampers were retained in all three axes. Martin Marietta’s Denver plant delivered the shell on 24 October 1972. In place of a full-scale tunnel entry, the programme managers Jack Kolf and Johnny Armstrong scheduled eleven kinds of ground and captive-flight test between February and August 1973. They found a purely mechanical aileron resonance that needed a damper on the actuator’s servo valve, flutter margins that had to be recomputed from measured vibration modes, and a main-gear down lock that released under the predicted drag load. Taxi tests on the lakebed reached 150 knots on about 4,000 pounds of rocket thrust without nose-gear shimmy.

The X-24B Flights

Manke made the first glide on 1 August 1973, launched at 40,000 feet, and landed on the lakebed at 200 miles an hour, and the first powered flight followed on 15 November 1973, in Reed and Hallion. Love reached Mach 1.752 on the sixteenth flight, and Manke flew the highest approach and landing, from 74,100 feet, on 22 May 1975. The pilots rated the X-24B’s subsonic handling 2.5 on the Cooper-Harper scale and compared it favourably with the T-38 and F-104. Its low effective dihedral turned the roll upsets that turbulence had produced on the earlier lifting bodies into a side-to-side motion the pilots found more acceptable, and in the landing pattern with the dampers off it handled well enough that the pilots said they could not believe the dampers were off.

Sim extracted the X-24B’s stability and control derivatives from flight data by a modified maximum likelihood method and compared them with the wind tunnel. Longitudinal static stability was generally smaller than predicted and pitch control effectiveness greater, yaw due to aileron was usually smaller than predicted, and the two lateral-directional static stability derivatives departed from prediction in opposite directions on either side of about Mach 0.7 and Mach 1.35. These are modest discrepancies beside the X-24A’s reversed derivative. Reed adds that the X-24B’s speed and performance resembled the projected Shuttle’s closely enough for it to be used to collect operational data for the Shuttle’s design, and it reached the Shuttle through its pilots as well. Francis Scobee, an Air Force transport test pilot and the only lifting-body pilot without a fighter background, flew it as a guest at the end of the programme, said that the experience led him to apply to the astronaut corps, and later commanded a Shuttle mission.

The Concrete Runway Landings

The concrete landings were a pilot’s proposal. Manke recommended them, the X-24B research subcommittee approved the proposal in January 1974, and Manke and Love flew a three-week programme of F-104 and T-38 approaches matched to the X-24B, more than 100 of them by Manke alone, in Reed and Hallion. Hallion also gives the reason the earlier lifting bodies never tried. They lacked nosewheel steering, and on the lakebed only the rudders and main-gear braking controlled the rollout. On 5 August 1975 Manke launched, climbed under power to 60,000 feet, and seven minutes after launch touched down at the planned mark 5,000 feet along runway 04/22. Love repeated it on 20 August 1975, on a flight that reached Mach 1.548 and 72,000 feet. Manke’s assessment, quoted by Reed, was that touchdown accuracies of plus or minus 500 feet could be expected, and that the concrete runway’s distance markers and features gave information the lakebed did not.

Set against Larson’s lakebed fit, the probability that a landing falls within 500 feet of the aim point is

\[P(|x| \le 500) = \Phi\!\left(\frac{500-\mu}{\sigma_x}\right) - \Phi\!\left(\frac{-500-\mu}{\sigma_x}\right) = 0.22\]

with $\mu = -112$ feet, $\sigma_x = 1{,}793.6$ feet and $\Phi$ the standard normal distribution function. Manke’s expected accuracy is a band several times narrower than the lakebed scatter,

\[\frac{\sigma_x}{500} = 3.6\]

a ratio that measures the change between the lakebed record and the concrete demonstration. Two landings cannot establish a distribution, and the documents read here give neither landing’s measured miss distance.

Comparison With Ground Prediction

Quantity	This model	Flight
X-24A maximum lift-to-drag ratio, smallest and largest base	4.39 and 2.99	4.25 and 3.28 measured
X-24B maximum lift-to-drag ratio, smallest base	4.88	4.50 measured
X-24B maximum lift-to-drag ratio, largest base	3.43	2.39 measured at Mach 0.8
Enterprise with tailcone	7.05	7.5 measured
Approach sink rate	10,400 ft/min	path angles of 10 to 25 degrees, not quoted as a sink rate
Flare height at 1.5 g	880 ft	900 ft, from 1,000 ft to level at 100 ft
Touchdown speed	199 mph at a solved 1.19 g	200 mph on the first X-24B flight, 212 mph mean for 25 X-24A landings

The flight-measured lift-to-drag ratios bracket the model. Matched by base area, Saltzman, Wang and Iliff’s assessment gives the X-24A 4.25 with the lower-flap bias at zero, its smallest wedge angle, and 3.28 with the upper flaps biased 21 degrees, against 4.39 and 2.99 here, and the X-24B 4.50 at its smallest base, against 4.88. The differences are

\[\frac{4.39}{4.25} - 1 = +3\%, \qquad \frac{2.99}{3.28} - 1 = -9\%, \qquad \frac{4.88}{4.50} - 1 = +8\%\]

The largest-base X-24B case is not a fair test. Its flight value of 2.39 was measured at Mach 0.8 with 40 degrees of upper flap, in Saltzman et al 2002, a transonic configuration in which compressibility adds drag that an incompressible polar does not carry, so the 3.43 used for the approach has no subsonic flight counterpart in that table. The same report states that the base pressures of both X-24 vehicles below Mach 0.8 were estimated from X-24B data at Mach 0.8 rather than measured, a point that bears directly on the base drag at the centre of this analysis.

The model is good to within about nine percent wherever a subsonic flight value exists at the same base area, using only published geometry, a Hoerner correlation with a flight-corrected coefficient, and a factor of three obtained by differentiation. The touchdown row is not an independent check, because the load factor was solved to reproduce it. What that row reports is the load factor, not an agreement.

The configuration on the approach is the weakest assumption in the chain. Cochrane and Graham state that the X-24A’s upper flaps were biased open, to 40 degrees above Mach 0.6, and closed up at low speed and for landing, with the pilot able to open them as speed brakes. With the base at its smallest, the same relations give an approach lift-to-drag ratio of 4.16 at 300 miles an hour, a path angle of 13.5 degrees and a sink rate of 6,169 feet a minute, and a 1.5 g flare that begins at 320 feet and exits at 274 miles an hour, leaving about 6,100 feet of float. The documented flare height of 900 feet is reproduced by the largest base and missed by a factor of almost three by the smallest. The result is consistent with approaches flown partly on the speed brakes, as Gentry describes, but it is an inference, because the X-24B’s flap setting on its final approaches is not stated in any source found.

The weakest link is the efficiency factor of 0.6, taken from the source’s comparison curve rather than derived. It enters the lift-to-drag ratio as a square root, so a twenty percent error in it moves the answer by ten percent, the same order as the agreement being claimed.

What the Data Changed

The Space Shuttle was designed to carry air-breathing engines for its landing approach, and it did not fly with them. The Phase B statement of work specified landing engines and a go-around capability, in Flight Test Results Pertaining to the Space Shuttlecraft.

The argument for them was straightforward. An orbiter that could go around, loiter, and be flown to a landing under power would be a far less demanding vehicle to operate, and its pilots could practise. The argument against was mass, and mass in an orbiter is payload, since every pound of engine and fuel is a pound not carried to orbit.

What the lifting bodies supplied was evidence that the engines were not needed. The X-24B’s two precision landings on concrete demonstrated that a vehicle with a lift-to-drag ratio near four could be brought to a chosen point on a runway by a pilot with no thrust available. The consequence, in the words of the programme’s account, was that shuttle designers eliminated the auxiliary engines.

The argument against the engines was made in public five years before the concrete landings. At the Flight Research Center’s symposium of 30 June 1970, collected as NASA TM X-2101 in Flight Test Results Pertaining to the Space Shuttlecraft, Kock and Fulton reported the HL-10’s powered-approach flights, in which three 500 pound rockets shallowed the final approach from about 18 degrees to 6 at 300 knots. Holding the speed while changing only the path angle needs a thrust equal to the change in the component of weight along the path,

\[T = W\left(\sin\gamma_1 - \sin\gamma_2\right)\]

and for the X-24B at the 23.2 degree approach derived above, a 6 degree glide slope would need

\[T = 8{,}500\left(\sin 23.2^\circ - \sin 6^\circ\right) = 2{,}460\ \text{lb}\]

or 29 percent of the vehicle’s weight, sustained through the final approach. Kock and Fulton concluded that a limited-duration propulsion system used this way brings few of the benefits of power and most of its penalties, and that even an orbiter with air-breathing engines and a go-around capability should be flown as if it were unpowered. Milton Thompson’s closing remarks in the same volume went further. The engines could not be started until the orbiter was subsonic, so it would have to be manoeuvred unpowered to a point near its destination in any case. The Center recommended that if the landing engines of the Phase B statement of work were fitted they should not be relied on, and judged an unpowered operational shuttle entirely practical.

The 1975 landings therefore did not introduce the argument. They demonstrated on concrete what the 1970 papers had argued from the lakebed and from simulation. Reed and the programme’s own account attribute the deletion of the engines to the X-24B landings, while Hallion credits the lifting-body trials as a whole with the confidence behind unpowered Shuttle landings. The documents read for this article do not date the deletion decision, so they cannot show whether it preceded or followed the landings.

The lifting bodies also told the Shuttle what a rough heat shield would cost at landing. The full-scale X-24A was tested under a simulated ablated surface whose roughness was taken from recovered PRIME vehicles, in Reed. On it and on a related subscale model the roughened surface cut the maximum lift-to-drag ratio by 20 to 30 percent, more than added friction alone explains, in Pyle and Ash. Reed puts the drag increase from ablated roughness at 15 to 30 percent and concludes that only the X-24A and X-24B would have kept adequate landing performance. At a given lift the lift-to-drag ratio falls in proportion to the drag,

\[\left(\frac{L}{D}\right)_\text{rough} = \frac{L/D}{1 + \Delta C_D/C_D}\]

so the X-24B’s landing value of 4.5 would fall to between 3.91 and 3.46, and the M2-F3’s 3.1 to between 2.70 and 2.38, against the value of 2.5 that F-104 trials had put at the border of the totally unacceptable. Reed’s statement that the M2-F3 would fall below 2.5 holds only toward the upper end of his range of drag increase.

The path from here to the orbiter runs through the Shuttle’s approach and landing record, in Nagel 1983, Powers 1984, Powers 1984, Brandenstein 1984 and Young and Underwood 1983, and the survey files the rest of that record under orbiters, spaceplanes and reusable launch vehicles. The decades after the lifting bodies were not idle either, and the aircraft literature of that middle period appears in the drag, handling qualities and flight control clusters.

The Contemporary Literature

Cluster	Records
Approach, flare and automatic landing	422
Orbiters, spaceplanes and reusable launch vehicles	333
Lift of low aspect ratio wings and bodies	284
Handling qualities and the pilot	248
Base drag, afterbodies and bluff-body wakes	246
The X-24 and lifting-body vehicles	236
Drag, performance and flight-determined aerodynamics	218
Flight control, stability and system identification	187
Landing gear, touchdown and landing loads	180
Entry and hypersonic flight of lifting vehicles	165
Propulsive and planetary landing	136
Flight test practice and research aircraft	81
Road vehicle drag	68
The standard atmosphere	18
Other aeronautical literature	29
Total	2,851

Everything the X-24B demonstrated is now done by software, and the one thing that has not moved is the corridor, because the corridor is set by energy rather than by skill.

A second answer is more radical. The X-24’s entire difficulty was that almost no energy could be added after the approach began. A booster that lands on its engine answers that by adding energy, and so never attempts an unpowered landing. Both answers are in service, in the Boeing X-37 and the Falcon 9, and they are opposites.

The cluster subsections after these analytic ones map the field as it currently stands.

The Flare Is Now a Control Law

Unpowered precision landing is no longer a piloting achievement but a guidance problem with a published solution, for an unpowered reusable launch vehicle in AL-Bakri and Kluever 2017, for unpowered drones and gyroplanes in Kim and Tahk 2019 and Fang et al 2019, for fixed-wing aircraft in flight test in Woodbury and Valasek 2016 and Sedlmair et al 2022, and for spacecraft in Lunghi et al 2015 and Robertson 2017, with a review in Pogosyan and Vereikin 2020.

The milestone came thirteen years after the X-24B. On 15 November 1988 the Soviet orbiter Buran flew one uncrewed orbital mission and landed itself on the runway at Baikonur, unpowered, in a crosswind, with no pilot aboard at any point. It was the demonstration Manke and Love flew, performed by a machine, at more than fifteen times the weight, since Buran’s dry mass alone was 62 tonnes Buran against the X-24B’s 8,500 pounds.

What the automation did not do is widen the corridor. The bounds derived above are energy bounds and they do not care who is flying. Written out, the touchdown speed is a function

\[V_\text{td} = F\left(n,\ \frac{W}{S},\ C_{D_0},\ k_i,\ \rho\right)\]

in which there is no term describing the pilot. An autonomous vehicle arriving too fast still floats, and one arriving too slow still runs out of speed. What automation provides is consistency in hitting the middle of a corridor whose width is set by aerodynamics, in Bottasso and Montinari 2015, Ye et al 2015, Zhou et al 2015, Ellerbroek et al 2016, Ackerman et al 2017, Lee et al 2017, Lombaerts et al 2017, Schuet et al 2017, Tekles et al 2017, Fellah and Guiatni 2019, Gabrys et al 2019, Zaal et al 2019, Van Baelen et al 2020, Campbell et al 2022, Kluever 2022, Yu et al 2022, Ma and Chen 2023, Altunkaya et al 2024, Catak et al 2024, Hsu et al 2024, Schieni et al 2024, Autenrieb 2025, Sarah et al 2025, Yue et al 2025.

The Other Answer Was to Refuse the Problem

A propulsively landed booster does not solve the unpowered landing. It declines to have one, as the powered descent guidance of Sagliano 2018, Wang et al 2019 and Botelho et al 2022 and the retropropulsion aerodynamics of Marwege and Gülhan 2023 assume. The propulsive and planetary landing cluster holds the remainder.

The comparison deserves care, because it is a trade and not a victory. The X-24B carried no propellant for a powered approach, only the small landing rockets that Reed lists among its equipment, and paid for that with a corridor four tenths of a g wide and no second attempt. A booster that lands on its engine carries propellant it could otherwise have spent on payload, and for that it gets a hover, a divert and an abort.

Which is better depends entirely on what is coming back. For a stage that is mostly empty tank the propellant is affordable. For a vehicle returning from orbit with a heat shield already sized for the entry, carrying landing propellant through that entry is expensive. That cost is why the winged and lifting vehicles that come back from orbit still land the X-24B’s way and the ones that come back from a few minutes of flight do not.

The Configuration Survived, Uncrewed

The shape is still flying, in India’s reusable launch vehicle technology demonstrator, in Sivan and Pandian 2018, and in the unpowered approach and landing guidance written for such vehicles, in Kluever and Neal 2015, S. Hameed and G. R 2021 and Yao and Xin 2023, and it survived in the form the X-24B pointed at and not the X-24A’s. Vehicles of this class are now designed to land themselves on runways, the capability the two 1975 landings were run to establish. The lifting-body and orbiter clusters below list further examples.

What did not survive is the pilot in the vehicle, and with the pilot went most of the reason to care about handling qualities in the way the programme did.

Computed Drag and a Still-Hard Base

Base and afterbody flows are among the least forgiving things to compute, as large eddy simulation of bluff-body wakes in Blanchard et al 2015 and Tran et al 2017, hybrid methods in Schmidt and Breuer 2015, nozzle separation in Yaravintelimath et al 2016 and turbulence-model work in Wu et al 2017 and Spalart and Garbaruk 2021 show. The separated region behind a blunt base is unsteady, three-dimensional and sensitive to the approaching boundary layer, the combination that steady turbulence models handle worst. The Hoerner correlation with a flight-corrected coefficient remains a serviceable engineering answer for the same reason it did in 1975.

The Physics Migrated to Lorries

The most active base-drag literature today is not aeronautical, as the boat tails, deflectors and append devices for heavy vehicles in khosravi et al 2015, Her et al 2016, Lee and Lee 2017, Kim et al 2020, Gao et al 2022 and Xu et al 2022 and the platoon studies in Tadakuma et al 2016 illustrate, and as the road vehicle cluster and the bluff-body share of the base drag cluster below count.

A heavy goods vehicle is a blunt-based body whose drag is dominated by its wake, the X-24’s problem in a different medium and at a lower speed. One of the authors of the lifting-body base-drag analysis also reassessed the aerodynamic design of heavy trucks, in Saltzman and Meyer 1999, drawing on coast-down tests of a box-shaped van, a two-axle truck and a tractor-semitrailer, and no statement of the connection could be more direct. Projectile base bleed and boat-tailing belong to the same family.

The physics travelled because the drag bucket does not care what the body is for. Base drag falls as forebody drag rises whatever the body, so the factor of three at the optimum is as true of a lorry as of a lifting body.

Lift Without a Wing, Computed

Aspect ratios near one remain awkward, in Lian 2011, Rockwell 2011, D and Singh 2016, Amin Boukenkoul et al 2017, Cao and Tafti 2018, Obeid et al 2019, Okamoto et al 2019, Qi and Wang 2019, Chandra 2020, Gildersleeve and Amitay 2020, Kase et al 2020, Barrett-Gonzalez and Wolf 2021, Chopra and Mittal 2021, Lin et al 2021, Degani 2022, Dutta et al 2022, Traub 2023, Aerodynamic Performance Enhancement of Low Aspect Ratio Military Drone Aircraft Wing through Employing Leading Edge Tubercles 2024, Jiang et al 2024, Verma and Kulkarni 2024, Berci 2025, Eraslan 2025, Lampropoulos and Sarris 2025, Numerical Investigation of Impinging Planar Shock Wave Interaction with Axisymmetric Slender Body 2025, Degani 2026. The classical relations still do not describe these shapes, because their lift comes substantially from crossflow and from vortices shed off sharp edges instead of from circulation in the ordinary sense, which also explains why the article had to take an efficiency factor from a source rather than compute one.

Handling Qualities Became a Discipline With Numbers

The question of whether a pilot can work with a vehicle is now posed quantitatively, in Hebbar and Pashilkar 2016, Efremov et al 2020, Bidinotto et al 2021, Ivler et al 2022 and Lampton et al 2024, with the rest in the handling qualities cluster below. The lifting bodies’ handling qualities record is part of that literature, in Manke et al 1970, Kempel and Manke 1974 and Kempel et al 1975, not for their shapes but because they were difficult aircraft flown to a standard by people who wrote down what happened.

What the Gear Sees, Now Measured

The touchdown conditions this article computes at residual path angles are now extracted from the routine flight data of transport aircraft to predict hard landings, in Ding et al 2020, Xiangzhang et al 2024, Dong et al 2025, Bansal et al 2026 and Chu et al 2026. Hard-landing prediction from routine flight data is an established subject, and the distribution of touchdown conditions across a fleet is a measured quantity where in 1975 it was an estimate.

What the Survey Shows

The aerodynamics have not moved. A truncated base still costs a factor of the square root of three in lift-to-drag ratio, the flare still has a corridor bounded from both ends, and the energy is still spent exactly once.

What moved is who flies it, and whether the problem is accepted at all. The X-24B’s pilots hit a fifteen-thousand-foot runway from a corridor a few tenths of a g wide, twice, and that was the demonstration. A modern vehicle of that class, such as the Boeing X-37, lands itself on a runway at the end of every mission. And a modern booster refuses the problem entirely by carrying the propellant to add energy back, an option the X-24B did not have and would not have wanted.

Approach, flare and automatic landing

The keystone’s descendants. Approach and landing guidance, the flare and its control laws, automatic landing of aircraft and drones, carrier landing, ground effect and the energy of the approach.

422 records. [180 Fault Tolerant navigation system for aircraft landing 1994] [Aerodynamic and Landing Measurements 1960] [Ahmed and Wyatt 2024] [Aircraft Landing Measurement System 1971] [Akametalu et al 2018] [Al-Bakri et al 2020] [Alatorre et al 2022] [Alexander and Camp 1983] [Amelin 2022] [Amzajerdian et al 2013] [Anderson 1975] [Anderson and Schmidt 1986] [Anglin 1962] [Anoshin et al 2012] [Aoki and Ishigami 2022] [Approach to solving the problem of landing an unmanned aerial vehicle on a moving landing platform 2025] [Ariante et al 2022] [Atter 1982] [Autenrieb 2025] [Automatic Landing 1964] [Aziz et al 2016] [Baigang 2024] [Banks and Paulson 1985] [Bansal et al 2026] [Barzegar et al 2025] [Bautista et al 2023] [Benbassat and Abramson 2002] [Bennett et al 2015] [Berninger 1990] [Kock and Fulton 1970] [Bian et al 2018] [Blick et al 1978] [Borowczyk et al 2017] [Borshchova and O’Young 2017] [Bray et al 1960] [Brockers et al 2011] [Brown and Lee 1971] [Brukarczyk et al 2021] [Bryson et al 1969] [Bull 1976] [Burchett 2003] [Burger 1986] [Cai et al 2026] [Campbell et al 2022] [Carter and Nagy 1996] [Catak et al 2024] [Chang et al 2026] [Cheatham 1959] [Chekanov 2025] [Chen 2018] [Cheng and Lai 2025] [Cheng et al 2022] [Chitrakaran et al 2005] [Chowhan 2016] [Chu et al 2024] [Chu et al 2026] [Cobar and Montalvo 2021] [Colwell 1966] [Computer vision-based approach for 2025] [Coombes et al 2017] [Corda 1995] [Corda et al 1994] [Cox and Geymayer 1970] [Craig and Heffley 1973] [Crane et al 1974] [Crumrine 1976] [Çeti̇n et al 2024] [Dai et al 2021] [Daidzic 2016] [Das et al 2018] [Day 2004] [de Alvear Cárdenas and Looye 2021] [de Bruin and Jones 2016] [de Ridder and Mooij 2009] [Del Pizzo et al 2018] [Deng and Duan 2016] [Deniz et al 2025] [Deshmukh and Majumdar 2025] [Development of a correction algorithm for the integrated navigation system of an unmanned aerial vehicle in the landing task on a moving platform 2024] [Dietenberger 1983] [Dieudonne et al 1976] [Ding et al 2020] [Dirs 1966] [Dong et al 2025] [Dougherty and Lee 2016] [Drinkwater and Cooper 1958] [Duan et al 2024] [Ducard and Carughi 2024] [Durand and Wasicko 1967] [Dutasatria and Darma 2020] [Ellis 1976] [Ema 1992] [Engle and Truly 1977] [EPilots is an algorithm that forecasts hard landing 2023] [Kawamura et al] [Kawamura et al] [Evangelisti and Pfifer 2024] [Extension of a portable tactical instrument approach and landing system 1972] [Fang et al 2018] [Fang et al 2019] [Fang et al 2026] [Faulders et al 1968] [Fearnside 1959] [Feinreich and Gevaert 1980] [Feinreich et al 1977] [Filyashkin and Sidorenko 2020] [Finch and Matranga 1959] [Flight Test Data Analysis of Hybrid Vertical Take-off and Landing Unmanned Aerial Vehicle 2016] [Flying Controls and Automatic Landing 1963] [Franklin and Innis 1972] [Franklin and Innis 1977] [Franklin and Innis 1978] [Franklin et al 1982] [Franklin et al 1986] [Freer 1952] [Rodriguez et al] [Gannett 1964] [Gao et al 2025] [Gautam et al 2017] [Gevaert and Feinreich 1977] [Gladkov I. A. Application of trajectory analysis to design a system of safe take-off and landing of aircraft 2017] [Gliding and Unpowered Flights 1995] [Goka 1975] [Grantham 2003] [Grewal et al 1976] [Guan et al 2018] [Gunn-Golkin et al 2010] [Guo et al 2026] [Guy 1976] [Haise 1977] [Hall and Boothe 1972] [Halyo 1977] [Halyo 1979] [Halyo 1983] [Halyo and Hueschen 1981] [Hameed et al 2024] [Han et al 2026] [Happy Landing 1990] [Harry and Trobaugh 1966] [Hart 1974] [Hassell and Judd 1972] [He et al 2026] [Hebbar and Pashilkar 2017] [Heffley 1974] [Heffley 1976] [Helliwell 1952] [Heo et al 2026] [Hess 2019] [Hess and Yousefpor 1992] [Hiba et al 2021] [Hinshaw et al 1964] [Hoffman et al 1970] [Hofmann et al 1978] [Holleman and Powers 1972] [Hornbuckle 2015] [Hryshchenko et al 2017] [Hryshchenko et al 2025] [Hsin 1974] [Hu et al 2022] [Hu et al 2022] [Hu Meng-Quan and Zhang Mei-Zhong] [Huang et al 2025] [Huang et al 2026] [Hueschen 1984] [Humphreys et al 1988] [Iizuka 2024] [Ilango and Ramanathan 2020] [Innis and Quigley 1961] [Isogaya et al 2019] [Ito and Sakai 2021] [Jacobs 1973] [Jayaraman et al 2022] [Jiang et al 2019] [Juang and Yu 2015] [Jump and Padfield 2005] [Jump and Padfield 2006] [Jung 2024] [Senthil Kumar and Shanmugam 2023] [Kai 2024] [Kang et al 2025] [Kariya et al 2019] [Kariya et al 2020] [Karmali et al 1984] [Kettle 1958] [Kim and Tahk 2019] [Kim et al 2025] [Kim et al 2026] [Kistyarev and Wang 2025] [Klochan et al 2017] [Kluever 2004] [Kluever 2007] [Knapp and Barton 1968] [Kock et al 1972] [Kong et al 2025] [Kongkaew et al 2022] [Koo et al 2015] [Kordos et al 2023] [Kozina 1976] [Kramer et al 2013] [Krammer et al 2022] [Kuchinka 1966] [Kumar and Padhi 2024] [Kurdel et al 2024] [Laili and Widayaka 2024] [Lambregts and Creedon 1980] [Le Ngoc et al 2010] [Lee 1990] [Lee and Mesbahi 2017] [Lee and Park 2021] [Lee and Park 2025] [Lee et al 2021] [Leeman et al 2022] [Lehman 1964] [Lehman 1966] [Li et al 2022] [Li et al 2024] [Li et al 2024] [Liao and Chen 2016] [Ling 1970] [Liu and Liu 2022] [Liu and Tan 2024] [Liu et al 2024] [Liu et al 2025] [Liu et al 2025] [Lorenzetti et al 1969] [Lovell and Lipson 1949] [Lowrance and Smith 1996] [Lu et al 2023] [Luers and Reeves 1975] [Lunghi et al 2015] [Lungu 2022] [Lungu and Lungu 2015] [Lungu and Lungu 2015] [Lungu and Lungu 2016] [Lungu and Lungu 2016] [Luo et al 2019] [Lyu et al 2018] [Ali Ahmed and Saleh 2019] [Ma et al 2022] [Ma et al 2025] [MACKlNNON and Madden 1972] [Mahmood et al 2023] [Maiuzzo 1970] [Makarenko et al 2017] [Mao et al 2023] [Mathematical model of the UAV landing approach system on the example of the course-glide path system 2023] [Matheny 1974] [Matranga 1961] [Matranga and Armstrong 1959] [Matranga and Menard 1959] [Mayanna et al 2006] [Mbikayi et al 2024] [McGee et al 1981] [McGee et al 1984] [McIntyre 1963] [Methodology for assessing the accuracy of UAV landing on the runway 2022] [DeVore et al 2022] [Miele et al 1987] [Miele et al 1988] [Mihalik and Keane 2022] [Miller et al 1974] [Misra and Bai 2019] [Mobile Autonomous Recovery Landing Principle and Control Method for Unmanned Aerial Vehicle 2024] [Modali et al 2020] [Mohammadkarimi and Nobahari 2018] [Mooij 2024] [Morio et al 2007] [Morio et al 2010] [Mu et al 2023] [Mu et al 2025] [Muehter 1974] [Munusamy et al 2022] [Nadkarni 1981] [Nagarajan and Jothiraj 2024] [Nagarani et al 2020] [Naka and Hashimoto 2015] [Navarro-Tapia et al 2017] [Nekrasov et al 2025] [Brown et al] [Newman 1982] [Ngo and Sultan 2022] [Ni et al 2023] [Nichele et al 2025] [Niessen 1973] [Nowak et al 2022] [Ohta and Sugiura 1973] [Othman and Kanazaki 2016] [Pan and Pi 2025] [Park 2020] [Parker and Goode 1976] [Pasek and Shanahan 1954] [Pavel 2022] [Payne 1968] [Peng et al 2025] [Pepper and Biesterveld 1973] [Pessanha Santos et al 2023] [Petrishchev 2018] [Petrishchev 2018] [Pham et al 2025] [Pierson 1985] [Pierson and Chen 1979] [Pogosyan and Vereikin 2020] [Polukhin and Ostapenko 2019] [Poritzky 1971] [Putman 1974] [Qi and Zhao 2025] [Richards et al 2001] [Riebe 1973] [Rigatos 2021] [Robertson 2017] [Rogers 1973] [Rogerson 1960] [Sai-fei et al 2016] [Sakaki and Ueba 2025] [Salgueiro Filipe et al 2009] [Sardou 1986] [Sánchez-Sánchez and Izzo 2018] [Schade and Crane 1965] [Schade et al 1954] [Schmidt and Anderson 1985] [Sebryakov et al 2019] [Seckel 1975] [Sederstrom et al 1973] [Sedlmair et al 2019] [Sedlmair et al 2022] [Seitz and Goodson 1973] [Setterfield et al 2021] [Shen et al 2024] [Shimizu et al 2019] [Silva Cotta et al 2024] [Slayton 1977] [Sleeman 1971] [Smith et al 1973] [Sözer and Kumbasar 2023] [Stevens 1985] [Stevens 1987] [Sun and Li 2021] [Sun et al 2025] [Suslov and Gagarskii 2025] [Swenson et al 1983] [Swenson et al 1984] [Tate 1975] [Tekaslan and Atkins 2025] [The algorithm of the color signal recognition at landing an unmanned aerial vehicle on an aircraft carrier in autonomous mode 2020] [The study of the problem for tiltrotor landing on the platform of an unmanned vehicle 2022] [Tomita and Ho 2025] [Trinh et al 2018] [Tripathi and Padhi 2016] [Tripathi et al 2018] [Tripathi et al 2024] [Trusfus and Abdullin 2021] [Ugnenko et al 2017] [Ulukır et al 2025] [Ulybyshev 2010] [Utterstrom and Kestek 1965] [Váňa et al 2020] [Verma 1991] [Visual Approach Slope Indicator 1962] [Vorobуev et al 2020] [Walker 1960] [Walker 1961] [Wallace and Gray 1963] [Wang and Mou 2025] [Wang and Wang 2024] [Wang et al 2016] [Wang et al 2017] [Wang et al 2018] [Wang et al 2020] [Wang et al 2022] [Wang et al 2022] [Wang et al 2022] [Wang et al 2024] [Wang et al 2024] [Wang et al 2025] [Wang et al 2026] [Warner 1981] [Watson et al 1981] [Watson et al 1983] [Watson et al 1986] [Wei et al 2024] [Weingarten 1984] [White 1963] [Wimpress 1966] [Woloshen 1974] [Wong et al 2020] [Wood 1972] [Woodbury and Valasek 2016] [Worth Assessments of Approach to Landing 1977] [Wu and Zhu 2024] [Wu et al 2024] [Wu et al 2026] [Xiangzhang et al 2024] [Xiao et al 2024] [Xie and Cheng 2015] [Xu et al 2019] [Xue et al 2023] [Yan and He 2020] [Yan et al 2023] [Yang et al 2026] [Yao et al 2024] [Yao et al 2025] [Yuan et al 2022] [Zaal et al 2019] [Zafirov 2019] [Zhai et al 2025] [Zhang 2023] [Zhang and Wang 2024] [Zhang et al 2024] [Zhang et al 2025] [Zhang et al 2025] [Zhao et al 2014] [Zhen et al 2018] [Zhen et al 2019] [Zhen et al 2020] [Zhou 2026] [Zhou and Wang 2023] [Zhu et al 2026] [Zou and Meng 2019] [Zou et al 2024] [Zwieback 1964] [Бабич et al 2017] [Чжан et al 2022]

114 of the 422 titles name an unmanned, uncrewed, autonomous or remotely piloted vehicle, and 111 of those date from 2015 or later, out of 242 records in the cluster from those years. 26 name the flare itself.

Orbiters, spaceplanes and reusable launch vehicles

The orbital vehicles that inherited the landing. The Space Shuttle orbiter’s approach and landing tests, aerodynamics, entry and handling, and the winged and reusable launch vehicles whose guidance now closes the same unpowered approach.

333 records. [2018, ISRO Releases the Special Issue o] [Aerothermodynamic Entry Environment of the Space Shuttle Orbiter 1983] [Al Bakri] [AL-Bakri and Kluever 2017] [Allen et al 1994] [Andrews 1977] [Andrews 1998] [Approximate Method of Predicting Heating on the Windward Side of Space Shuttle Orbiter and Comparisons with Flight Data 1983] [Ashikhmina and Prosuntsov 2021] [Ashikhmina et al 2021] [Ashkenas et al 1982] [Ashkenas et al 1983] [Audley and Hodge 1982] [Balesdent et al 2023] [Barton and Culp 1985] [Bentley 2009] [Bentley 2009] [Berkes 1992] [Bert 1989] [Betin 1991] [Beyond Buran] [Béjar-Romero et al 2016] [Blanchard and Larman 1987] [Blazek and Carrier 1974] [Bollino et al 2006] [Bonner and Pride 1976] [Bourne and Kirsten 1983] [Brand 1981] [Brandenstein 1984] [Brauckmann and Scallion 2004] [Brevault et al 2020] [Brice and Sugano 1978] [Brociek et al 2023] [Buck and Blanchard 1986] [Buffo 1990] [Buran 2025] [Buran in the spotlight] [Burchett] [Calhoun 2000] [Cameron 1974] [Caplin] [Carter and Brown 1974] [Carter and Kaul 1975] [Carter and Sims 1981] [Castaldi et al 2023] [Chartres et al 2005] [Chase 1979] [Chaudhary et al 2001] [Chen et al 2025] [Chen et al 2026] [Cheng et al 2021] [Cherry and De Wolf 1970] [Coakley] [Colwell 1976] [Compton et al 1981] [Cook 1995] [Corban et al 2001] [Coue 2003] [Crawford and Duiven 1973] [Crawford and Duiven 1973] [Crawford and Duiven 1974] [De Oliveira and Lavagna 2023] [De Oliveira and Lavagna 2024] [De Ridder and Mooij 2011] [Desikan and Srinivasan 2018] [Devanath and Beebi 2016] [Doman 2004] [Dussy et al 2011] [Dutheil et al 2016] [Edwards and Foster 1973] [Edwards et al 1975] [Effect of Ground Proximity on Aerodynamic Forces and Moments of Reusable Launch Vehicle at Subsonic Speed 2016] [Elias 1974] [Elvin 1996] [Energiya-Buran 2007] [European Space Agency launches mini-spaceplane 2015] [Ewell 1982] [Feustel-Büechl 1988] [Fisher et al 2002] [Flight Test Results Pertaining 1970, Flight Test Results Pertaining to] [Fonseca and Dilão 2018] [Freeman 1980] [Freeman and Spencer 1980] [Fullerton 1975] [Garrett et al 1977] [Gawehn et al 2011] [Gérard and Tumino 2006] [Gibney 2015] [Gong et al 2022] [Grigoli 2024] [Hagopian 2002] [Halbe et al 2014] [Hall and Shtessel 2005] [Hameed and Bindu 2019] [Hameed and Bindu 2022] [Hanson 2000] [Hardy 1972] [Harting 1981] [Hawthorne 1976] [Hawthorne 1976] [Hawthorne 1976] [Heath et al 1977] [Hermes Spaceplane in MBB Wind Tunnel 1988] [Hodge et al 1981] [Homan et al 1980] [Horneman and Kluever 2004] [Huang et al 2015] [Huang et al 2024] [Igreja and Lemos 2022] [Ikawa 1977] [Jayan et al 2024] [Jia et al 2020] [Jiang and Ordonez 2008] [Jiang and Ordóñez 2009] [Jiang and Yang 2014] [Johnson and Dimarco 1972] [Jones and Crawford 1974] [Junaid R and Beebi M 2015] [Jung et al 2025] [Jung et al 2025] [Justiz and Patel 1988] [Kafer 1982] [Kaplan 2002] [Karr et al 1986] [Ke and Feng 2015] [Keene 1970] [Kiehn 2020] [Kim et al 2023] [Kluever 2007] [Kluever 2022] [Kluever and Horneman 2005] [Kluever and Neal 2015] [Kluever et al 2009] [Kobayashi and Maita 1995] [Krek and Stalker 1992] [Lan et al 2016] [Lan et al 2020] [Lan et al 2021] [Launius 2013] [Law and Stegall 1984] [Lee 1977] [Lei et al 2017] [Li and Hu 2018] [Li et al 2019] [Li et al 2026] [Liang et al 2014] [Liang et al 2016] [Liao et al 2023] [Liao et al 2023] [Liao et al 2026] [Liu et al 2017] [Loddoni et al 2010] [Lozino-Lozinskii and Neiland 1989] [Lu 1996] [Lu 1997] [Ma 1992] [Mallet et al 1992] [Martindale and Carter 1975] [Mathavaraj and Padhi 2020] [Mathavaraj et al 2010] [McGee et al 1970] [Meckler 1965] [Mehta et al 2016] [Mennell 1975] [Menon et al 2025] [Merlin 2006] [Meyerson 1990] [Meyerson 1998] [Michael A. Bolender 2006] [Minott et al 1976] [Miotto and LePome 2003] [Mo et al 2024] [Monaco et al 2001] [Montez and Madden 1982] [Moore et al 1980] [Morth 1972] [Morth 1973] [Mu et al 2016] [Mu et al 2018] [Mu et al 2019] [Mu et al 2022] [Mukundan et al 2022] [Nag et al 2023] [Nagel 1983] [Nair and Kukreja 2025] [Nebylov and Tomita] [Nebylov et al 1999] [Ning et al 2007] [Nugroho et al 2024] [Numerical Optimization on Approach and Landing for Reusable Launch Vehicle 2016] [Nutt and Martindale 1976] [Nutt et al 1979] [Oglesby 1975] [Osder 1970] [Osder and Keller 1971] [Pesch 1980] [Pezzella and Viviani 2016] [Pezzella et al 2011] [Pidvysotskyi 2021] [Powers 1984] [Powers 1984] [Powers 1986] [Powers and Sarrafian 1986] [Prasad 2022] [Price and Blanchard 1981] [Pruin 1970] [Radhakrishnan et al 2023] [Ragsdale et al 1974] [Raillon et al 1992] [Rasky et al 2006] [Redding 1984] [Reusable Launch Vehicle 1995] [Ricciardi et al 2019] [Riley and Miller 1980] [Riley and Miller 1982] [Romere and Whitnah 1983] [Romere et al 1978] [Romere et al 1979] [S. Hameed and G. R 2021] [Sarkar et al 2021] [Saunders et al 1991] [Schmitt and Burchett 2004] [Schouler et al 2021] [Schouler et al 2021] [Shaffer et al 2005] [Shao et al 2014] [Shawyer 2023] [Shtessel and Krupp] [Shtessel et al 1997] [Shtessel et al 2000] [Shtessel et al 2003] [Siemers and Larson 1978] [Siemers and Larson 1979] [Sillen 1993] [Simplício et al 2019] [Singh et al 2022] [Sivan and Pandian 2018] [Smith] [Smith 1981] [Smith and Edwards 1980] [Smith et al 1974] [Soard 1974] [Soard 1975] [Songhui et al 2020] [Space Shuttle Aerothermodynamics Technology Conference. Volume 3 Aerodynamics 1971] [Space Shuttle Orbiter Approach 1977] [Space Shuttle Orbiter Approach 1978] [Space Shuttle Program Orbiter Approach and Landing Test 1977] [Space shuttle trajectory management, navigation, guidance, and control during approach and landing Interim report 1970] [SPACEPLANE HISTORY 2002] [SPACEPLANE LOW-COST POTENTIAL 2002] [Spain et al 1993] [Stallings 1981] [Stapleton et al 1997] [Streb 1973] [Su and Liu 2025] [Su and Liu 2025] [Su and Wang 2015] [Su et al 2021] [Su et al 2021] [Surber and Olsen 1978] [Tariq et al 2026] [Tate 1974] [Taylor 2004] [Teper et al 1981] [Tetlow et al 2000] [The birth of Buran] [The Buran cosmonaut team] [The Marriage of Buran 2013] [The roots of Buran] [THE SPACEPLANE SPACE AGE 2002] [Throckmorton 1981] [Throckmorton 1982] [Throckmorton 1993] [Tian et al 2015] [Tian et al 2015] [Tournes and Johnson 1998] [Tournes and Johnson 2001] [Tsikalas and Dyer 1982] [Tumino and Mancuso 2016] [Tuohy 1998] [US Air Force spaceplane returns to Earth 2010] [van den Abeelen 2017] [Van Ghele et al 2018] [Vella] [Velligan and Svendsen 1971] [Walker 1981] [Walyus and Dalton 1991] [Wang and Wu 2016] [Wang et al 2018] [Wang et al 2022] [Wang et al 2022] [Wang et al 2022] [Wang et al 2023] [Wang et al 2024] [Wei et al 2019] [Weingarten and Chalk 1983] [Wells 1985] [Wetzel] [Widnall and Morth 1972] [Williams and Curry 1983] [Wu and Zhang 2023] [XCOR, Developing the Next Generation Spaceplane 2016] [Xu and Lan 2018] [Xu et al 2023] [Xu et al 2025] [Xu et al 2025] [Xu et al 2025] [Xue et al 2024] [Yamada and Suzuki 2016] [Yan and He 2015] [Yang 2025] [Yang et al 2016] [Yang et al 2024] [Yao and Xin 2023] [Young 1982] [Young and Underwood 1982] [Young and Underwood 1983] [Yuta Akai et al 2007] [Zaragoza Prous et al 2025] [Zhang et al 2008] [Zhang et al 2017] [Zhang et al 2021] [Zhang et al 2022] [Zhang et al 2022] [Zhang et al 2025] [Zheng and Liu 2018] [Zheng et al 2014] [Zhesheng Jiang and Ordonnez 2007] [Zhi et al 2015] [Zhou et al 2015] [Zhou et al 2025] [Zuppardi and Mongelluzzo 2023]

152 titles name a reusable launch vehicle, and 99 of them date from 2015 or later, while 114 name the Space Shuttle or its orbiter, 105 of those before 1990. The unpowered approach passed from a flight programme to a guidance problem after the Shuttle.

Lift of low aspect ratio wings and bodies

Lift at aspect ratio near one. Low aspect ratio and slender wings, lifting-surface and slender-body theory, vortex lift and high lift, the aerodynamics behind a lifting body’s polar.

284 records. [A Spreadsheet Tool for the AERODAS Model for Calculating Airfoil Pre-Stall and Post-Stall Lift and Drag Characteristics 2018] [Aerodynamic Performance Enhancement of Low Aspect Ratio Military Drone Aircraft Wing through Employing Leading Edge Tubercles 2024] [Ailor and Eberle 1976] [Alexander 1971] [Cianciolo et al 2020] [Amin Boukenkoul et al 2017] [Analysis for Calculating the Lift-to-Drag Ratio for Flying Plates Having Square or Circular Shapes 1983] [Ando and Ichikawa 1979] [Andrews 1970] [Aprovitola et al 2022] [Balla and Vad 2022] [Bannink and Reyn 1968] [Barrett-Gonzalez and Wolf 2021] [Bass and Bertin 1970] [Bass et al 1982] [Beals and Targoff 1953] [Ben-Gida et al 2020] [Berci 2025] [Bihrle and Bowman 1981] [Bleviss and Struble 1954] [Bourisli and Hamadeh 2020] [Bridson and Hancock 1970] [Brune and Dusto 1972] [Bukanov and Zherekhov 2016] [Burkhart 1977] [Calarese 1987] [Campbell 1976] [Chandra 2020] [Chang 1982] [Chang and Muirhead 1987] [Chen et al 2016] [Clarke 1958] [Cole and Malmuth 1989] [Cong et al 2023] [Conner et al 1965] [Crowell and Crowe 1973] [Cunningham 1971] [D and Singh 2016] [Dakka and Johnson 2019] [Darden 1985] [Davenport 1972] [Davenport 1974] [De Troyer et al 2022] [Deere et al 2017] [Deese and Agarwal 1990] [Degani 2022] [Degani 2026] [DeVoria and Mohseni 2017] [Deyoung 1980] [Dike and Dunn 1958] [Dodbele and Plotkin 1987] [Dollyhigh 1978] [Dong et al 2022] [Donnelly et al 2006] [Wells 2014] [Dragos 1985] [Dragoş 1987] [Dragoş 1990] [Drela 1990] [Durmus 2021] [Dutta et al 2022] [Edge and Perkins 1995] [Ehlers 1961] [Eraslan 2025] [Esabat et al 2025] [McFadden and Bons] [Evans 1954] [Fairuz Izzuddin Romli et al 2023] [Ferrier et al 2016] [Fiddes et al 1985] [Fink and Lastinger 1961] [Fokin 1998] [Fournier and Sleeman 1974] [Fraenkel 1958] [Frink 1982] [Frost and Rutherford 1963] [Furey 1980] [Gallay and Laurendeau 2016] [Gardner and Weir 1966] [Gersten 1963] [Ghee and Taylor 2000] [Giguere et al 1997] [Gillespie 1960] [Gladkov and Panteleev 1988] [Gopalarothnam and McGowan 2008] [Graham et al 1954] [Greene 1977] [Haftka 1977] [Hall and Sandahl 1950] [Hancock 1960] [Hancock 1972] [Hartley et al 1965] [Hastings 1956] [Hauptman 1987] [Henderson 1966] [Hess 1972] [HlCKEY 1969] [Hopkins 1951] [Hopkins 1977] [Hortsen et al 1983] [Hugo and Lago 2022] [Jain 1988] [Nissen and Gadeberg 1944] [Jardin and Colonius 2018] [Jardin and David 2017] [Jenkins 1986] [Jiang et al 2024] [Johnson and Craig 1976] [Jones 1976] [Judd 1969] [Karakulov and Mitiukov 2026] [Karn et al 2021] [Kase et al 2020] [Katz 1989] [Kellaway 1972] [Keller and Rudnik 2015] [Kida and Miyai 1978] [Kieszek et al 2024] [Kolesar 1971] [Kolesar et al 1970] [Kolesar et al 1970] [Kolesnikov 1967] [Korkischko and Konrath 2017] [Krishnan and Roy 2022] [Kuessner 1954] [Kuhlman and Liaw 1987] [Kuhn 1959] [Kulakowski and Haskell 1961] [Kumar et al 2025] [Laitone 1989] [Lamar et al 1981] [Lampropoulos and Sarris 2025] [Lampropoulos et al 2025] [Lan 1984] [Lapygin and Tret’yakov 1986] [Lauchle 1974] [Lawrence 1951] [Lawrence 1953] [Lee and Libbey 1961] [Leite et al 2022] [Leyds 1956] [Lian 2011] [Liebeck 1978] [Liebeck and Ormsbee 1970] [Lift/Drag Ratios of Optimised Slewed Wings at Supersonic Speeds 1962] [Lin et al 2021] [Liu et al 2021] [Liu et al 2021] [Lobanovskii 1983] [Lock 1986] [Lopez-Morales et al 2026] [Loth and Boyle 1969] [Lottati 1984] [Lu et al 2018] [Lucero 1985] [Lundry 1967] [Lundry 1977] [Ma 1989] [Mabey and Welsh 1987] [Maikapar 1966] [Maikapar 1993] [Maita et al 1982] [Makizono et al 2015] [Mann and Carlson 1991] [Marchman and Abtahi 1985] [Margason and Morgan 1975] [Andino et al] [Martin 1964] [Martina 1956] [Maskew 1977] [Mastrocola and Assadourian 1947] [McCormick 1959] [McCutchen 1989] [McDonald and Stevens 1970] [Koklu et al] [Menon et al 2022] [Messiter 1963] [Meyn et al 1993] [Miele and Damoulakis 1969] [Miles 1953] [Miles 1954] [Milla and Blick 1966] [Mineck and Vijgen 1993] [Mirels 1953] [Mitcham et al 1951] [Morikawa and Puckett 1951] [Morton 1956] [Mueller and Torres 2001] [Muhammad et al 2025] [Nguyen et al 2018] [Nixon 2006] [Nonweiler 1955] [Nonweiler 1955] [Nonweiler 1960] [Nugent 1959] [Numerical Investigation of Impinging Planar Shock Wave Interaction with Axisymmetric Slender Body 2025] [Obeid et al 2019] [Oh and Choi 2018] [Okamoto et al 2019] [Oktay et al 2018] [Ormsbee and Chen 1972] [Ostapenko and Stradomskiy 2018] [Pasandideh Fard and Sahaf 2016] [Pate 1964] [Pate and Deitering 1963] [Patton 2004] [Pfaff 1965] [Pfenninger and Vemuru 1988] [Polhamus 1953] [Polhamus 1968] [Polhamus 1984] [Predachenko and Lemko 2019] [Qi and Wang 2019] [Ramprasadh and Devanandh 2015] [Rao 1980] [Rehman 2022] [Revell 1971] [Ribner 1960] [Osborne and Kelly 1960] [Rockwell 2011] [Rodden 1984] [Ross et al 1995] [Langston et al] [Schoombie et al 2017] [Schwartzberg 1975] [Sheila Tobing 2022] [Shen 1952] [Shigenori and Michiyo 1985] [Sibert 1943] [Smetana and Knepper 1973] [Smith 1968] [Smith 1990] [Smith and Klettner 2022] [Smith et al 1970] [Snyder and Zumwalt 1969] [Soontornpasatch 2018] [Spence 1956] [Spreiter and Steffen 1946] [Stark 1985] [Stewart 1980] [Streather 1975] [Sugai 1965] [Sugiyama 1971] [Takallu and Williams 1984] [Tanaka et al 2024] [Tao et al 2017] [Tao et al 2018] [Tao et al 2021] [The Pursuit of Maximum Lift 1955] [Tinoco et al 1987] [Tkalenko 1969] [Torres and Rahai 2024] [Traub 2023] [Trobaugh et al 1980] [Tsien 1957] [Ueda and Dowell 1982] [Van Dommelen 1995] [Varshney et al 2019] [Varshney et al 2020] [Varshney et al 2022] [Verma and Kulkarni 2024] [Vidal et al 1961] [Wagner 1969] [Valarezo et al 1993] [Wang 2019] [Wang and Zhou 2022] [White 1971] [Whitfield and Griffith 1963] [Wilmott 1986] [Windsor 1962] [Winograd and Miles 1956] [Witcher et al 2018] [Wood and Covell 1985] [Woods and Friswell 2015] [Woodward 1956] [Wootton 1967] [Yang et al 2025] [Yates 1966] [Yates and Donald 1986] [Yeo and Johnson 2015] [Zauner et al 2023] [Zhang 2024] [Zhang et al 2017] [Zhao et al 2023]

58 titles name a low or small aspect ratio and 27 name a slender wing or body.

Handling qualities and the pilot

Whether a pilot can fly it. Handling and flying qualities, pilot models and ratings, pilot-induced oscillation, workload, approach displays and the simulators that test them.

248 records. [Ackerman et al 2017] [Adams and Hatch 1971] [Air Force Test Pilot School Edwards Afb Ca 1969] [Air Force Test Pilot School Edwards Afb Ca 1990] [Air Force Test Pilot School Edwards Afb Ca 1991] [Air Force Test Pilot School Edwards Afb Ca 1992] [Anderson 1960] [Anderson 1970] [Anderson 1985] [Anderson and Schmidt 1987] [Antonakis 2025] [Antonakis 2025] [Ashkenas 1965] [Ashkenas 1965] [Ashkenas 1984] [Bailes et al 1975] [Bailey and Smith 1982] [Baron and Levison 1973] [Batson et al 1992] [Baughman and Longeauay 2015] [Benbassat 2005] [Berger et al 2021] [Berger et al 2022] [Berger et al 2022] [Berry 1986] [Berry and Powers 1970] [Berry and Powers 1970, Handling qualities of the XB-70 a] [Bidinotto et al 2021] [Billings and Durlach 2008] [Billings and Durlach 2010] [Bivens 1986] [Bleeg et al 1967] [Bortolussi et al 1987] [Brauser 1982] [Bray 1980] [Bray and Scott 1981] [Bray and Scott 1981] [Breul 1963] [Burian et al 2013] [Callaghan and Kunz 2021] [Campos and Marques 2021] [Cao et al 2022] [Carlson 1958] [Cavallo et al 1990] [Chase 1971] [Chowhan et al 2019] [Condit et al 1966] [Connor and Wierwille 1983] [Crombie and Moorhouse 1980] [Dana et al 1969] [Daughaday and Duwaldt 1955] [Decker 1992] [Delgado et al 2000] [Delgado et al 2001] [Difranco 1970] [DiFranco 1971] [Doetsch 1975] [Dooley 1977] [Dorr et al 1992] [Dorr et al 1994] [Douglas Aircraft Co Long Beach Ca 1963] [Drinkwater and Vomaske 1966] [Dunham et al 1971] [Dussart et al 2019] [Eckhart 1972] [Edwards et al 1997] [Efremov et al 2020] [Efremov et al 2022] [Eichler 1970] [Elkins and Hatfield 1970] [Eney 1968] [Falcão Arantes Filho and de Andrade 2016] [Favaro et al 2025] [Fellah and Guiatni 2019] [Flight deck environment and 1973] [Ford 1989] [Franklin and Koenig 1973] [Franklin et al 1976] [Franklin et al 1980] [Galanis et al 1998] [Gallagher 1971] [Garg and Schmidt 1988] [Garkushenko and Vinogradov 2016] [Gartner and Baldwin 1973] [Gerdes and Hynes 1971] [Gerken 1979] [Grant et al 2015] [Grantham 1989] [Grantham and Williams 1987] [Grantham et al 1972] [Grantham et al 1985] [Griffin and Bellaire 1968] [Harper and Cooper 1986] [Harper and Robert P. 1955] [Harper and Sardanowsky 1969] [Hart 1987] [Hebbar and Pashilkar 2016] [Heffley and Jewell 1972] [Heffley and Schulman 1981] [Heffley et al 1982] [Henriquez Huecas et al 2022] [Herrington et al 2023] [Hess 1984] [Hess 2016] [Hess and Chan 1988] [Hess and Mnich 1986] [Hindson et al 1982] [Hirsch and McCORMICK 1966] [Hodgkinson et al 1976] [Hoh and Mitchell 1983] [Hooks and McMurry 1983] [Howard 1974] [Humphreys-Jennings et al 2020] [Huntoon et al 1979] [Hynes and Scott 1976] [Hynes et al 1988] [Ioannis and Ioannis 2026] [Ivler et al 2022] [Jenkins 2008] [Ji et al 2017] [Ji et al 2022] [Jing et al 2020] [Johnson and Phatak 1990] [Johnston et al 1965] [Johnston et al 1965] [Jusko and Berger 2026] [Key 1982] [Kidd and Bull 1963] [Kleinman and Baron 1973] [Kozhanov et al 2022] [Kraiss and Baty 1978] [Kramer et al 2012] [Krebs et al 1977] [KrishnaKumar et al 1995] [Kuchta and Friedman 1972] [Lampton et al 2024] [Lawrence et al 2018] [Lebacqz and Forrest 1982] [Levi and Nelson 1964] [Levison 1982] [Li et al 2024] [Lombaerts et al 2017] [Majendie 1963] [Malcom 1969] [Malpica and Lusardi 2013] [Mandal and Gu 2016] [McCormick 1969] [Memon et al 2021] [Merhav and Grunwald 1978] [Merrick 1971] [Merrick et al 1990] [Middleton and Bergeron 1974] [Miller 1970] [Miller and Clark 1965] [Mitchell et al 2003] [Miyajima 1969] [Moore et al 2008] [Mudd 1969] [Murrell 1969] [Myers et al 1982] [Myers et al 1986] [Myers et al 1987] [Nagata et al 1973] [Naish 1980] [Neuhaus 2018] [Newton and Kroo 2025] [Nguyen et al 2021] [Nicholson 1973] [Nonnenmacher and Jones 2016] [Palmer and Petitt 1977] [Parrish and Martin 1975] [Parrish and McKissick 1979] [Parrish et al 1976] [Parrish et al 1979] [Pasha et al 1982] [Perrone 1983] [Perrone 1984] [Portapas and Cooke 2020] [Powers 1980] [Powers 1982] [Powers 1986] [Prévôt and Onken 1995] [Proceedings of the Seventeenth 1981] [Raney et al 1995] [Rauer 2019] [Reeder 1958] [Reschak 1971] [Rhoads 1967] [Richards et al 2015] [Rohling 1969] [Saetti and Rogers 2024] [Sarrafian 1984, Evaluation of HiMAT aircraft land] [Sarrafian 1984] [Sarrafian and Powers 1988] [Schmidt 1979] [Schuler et al 1972] [Shafer et al 1983] [Shafer et al 1984] [Shomber and Gertsen 1967] [Single pilot IFR flight surve 1986] [Slaughter 1958] [Smith 1977] [Smith 1979] [Spady 1977] [Spady 1978] [Srinathkumar 2015] [Stapleford and Teper 1965] [Stollery and Dyer 1989] [Sun et al 2020] [Swaim and Yen 1979] [Tanaka 1981] [Teper and Stapleford 1966] [Tole et al 1982] [Tran et al 2017] [Tritschler and O’Connor 2016] [Twisdale and Kirsten 1984] [V-STOL displays for approach and landing 1973] [Wang and Chen 2024] [Wang et al 2019] [Wang et al 2023] [Wang et al 2025] [Wasicko 1972] [Wasserman and Mitchell 1973] [Weingarten and Chalk 1984] [Weingarten et al 1986] [Weingarten et al 1986] [Wickens and Dixon 2002] [Wierwille and Connor 1983] [Wilhelm and Schafranek 1986] [Decker et al 1993] [Willshire et al 1993] [Wilson et al 1993] [Wright and Lappos 1981] [Xu et al 2019] [Xu et al 2025] [Xu et al 2025] [Yin and Wang 2017] [Yoon et al 2016] [Yu et al 2020] [Yuan et al 2022] [Zaal et al 2015] [Zaal et al 2018] [Zanoni et al 2022] [Zaytseva et al 2021] [Zhang et al 2017] [Zhao et al 2020] [Zhong et al 2018] [Zhou et al 2017]

23 titles name pilot-induced oscillation and 84 name the approach or the landing, the task in which the lifting bodies’ handling was judged.

Base drag, afterbodies and bluff-body wakes

The cost of a blunt base. Base drag and base pressure, boattails and afterbodies, base bleed, and the wakes of bluff bodies.

246 records. [Addy 1969] [Addy 1970] [Aman Prakash et al 2024] [Amico et al 2024] [Ando and Nishiwaki 1971] [André Luiz Tenório Rezende et al 2026] [Asadullah et al 2018] [August and McKinney 2005] [Aulehla and Besigk 1982] [Aziz et al 2020] [Aziz et al 2022] [Barros et al 2016] [Bauer 1980] [Belaidouni et al 2016] [Bergman 1971] [Blaha et al 1976] [Blanchard et al 2015] [Brackston et al 2016] [Brackston et al 2018] [Brazzel 1963] [Britcher and Alcorn 1991] [Brogna and Hawks 1978] [Bulathsinghala et al 2017] [Bulathsinghala et al 2018] [Buteau et al 1980] [Calarese 1979] [Calarese 1980] [Calarese and Walterick 1979] [Cao and Tafti 2018] [Capone et al 1999] [Carlson and Reubush 1996] [Cassanto 1969] [Cassanto 1971] [Cavalleri and Posey 1988] [Chamberlin 1972] [Chamberlin and Blaha 1973] [Chapman 1951] [Chapman and Perkins 1951] [Chen et al 2022] [Chima and Gerhart 1982] [Ching and Eaton 2019] [Choi et al 2015] [Chopra and Mittal 2021] [Chow 1959] [Britcher et al] [Britcher et al] [Component Analysis and Synthesis for Fully Separated Flows with Special Consideration of Base Drag Reduction by Combusti 1976] [Compton 1996] [Connolly 1965] [Craft and Brazzel 1970] [Cruikshank et al 2025] [Dali and Jaramaz 2019] [Damljanović et al 2021] [Dawson and John G. 1962] [de Souza et al 2019] [De Stefano et al 2016] [Decker 2002] [Deere and Hunter 1999] [Deiwert 1981] [Dennis Quadros et al 2023] [DeSpirito 2005] [Di Camillo and Fisher 1959] [Ding et al 1988] [Donaldson 1955] [Dougherty and Johnson 1993] [Durgesh et al 2004] [Elangovan et al 2021] [Famellos et al 2024] [Fan and Cadot 2023] [Fan et al 2024] [Fang 2025] [Foss et al 1958] [Fransson and Talamelli 2011] [Gai and Patil 1980] [Gai and Sharma 1981] [García-Baena et al 2021] [Garodz 1975] [Gas Generators for Base Drag Reduction Fumers 1976] [Gatto and Babinsky 2018] [Gholap et al 2021] [Gildersleeve and Amitay 2020] [Gloss and Sewall 1983] [Gogish and Pokrovskii 1978] [Guttag and Reis 2017] [Haffner et al 2020] [Heltsley and Crosswy 1983] [Hirst et al 2015] [Hoerner 1950] [Hoffmann et al 2015] [Howard and Goodman 1987] [Howell et al 2003] [Huang and Wei 2025] [Hubbartt and Strahle 1981] [Huerta 1969] [Hughes and McDonald 1965] [Iseri and Kameda 2021] [Iseri et al 2021] [Jackson 1955] [Kayser et al 1983] [Kentfield et al 2006] [Khurana et al 2018] [Kim et al 2017] [Knight and Tso 2005] [Kuhn 1981] [Kumar S et al 2022] [Kuptsov and Ostroukhova 1977] [Lavrukhin and Talyzin 2017] [Lehnert and Schermerhorn 1959] [Li and Zhou 2022] [Li et al 2015] [Lockman 1967] [Lorite-Díez et al 2019] [Lucas 1978] [Lunghi et al 2024] [Mair 1965] [Mair 1969] [Mao et al 2021] [Mariotti et al 2015] [Mariotti et al 2017] [Mariotti et al 2019] [Mariotti et al 2024] [Martin and Brazzel 1970] [Matsubara et al 2020] [Maull 1980] [McConnell et al 2024] [Merz 1979] [Merz et al 1985] [Mikhail 1979] [Moldovan et al 2024] [Moller and Elliott 1972] [Morel 1979] [Moussie et al 2024] [Mueller 1985] [Natarajan et al 2024] [Naughton 1999] [Nekkanti et al 2023] [Nenni 1980] [Nguyen et al 2024] [Nguyen et al 2026] [Nicolás-Pérez et al 2017] [Nieto et al 2024] [Norman 1969] [Numerical Research on Effect of Base Bleed Type on ‎Operation Process of Base Bleed Projectile 2021] [Numerical Study on the Drag Reduction for a D-Shaped Bluff Body with Wavy Trailing Edge Structures 2025] [Park and Rokhsaz 2003] [Park et al 2022] [Park et al 2024] [Patel and Guven 1976] [Paul et al 2022] [Payne 1980] [Payne et al 1980] [Peters 1981] [Peterson 1981] [Piddington 1957] [Pinn] [Platou 1974] [Platou 1975] [Platou and Nielsen 1976] [Powers 1988] [Powers 1988] [Powers et al 1986] [Presz et al 1978] [Price 1978] [Price and Earl A. 1981] [Pritchard 1969] [Probst et al 2017] [Puchalski and Kowalick 1976] [Rabaa and Kuppusamy 2022] [Rahma and AlQadi 2025] [Raju and Viswanath 1998] [Ranjan and Gaitonde 2020] [Rao et al 2023] [Rathore and Havaldar 2023] [Reubush 1975] [Reubush 1975, The effect of Reynolds number on] [Reubush 1976] [Reubush 1976, Effect of Reynolds number on the] [Rittenhouse 1959] [Robinson 1978] [Robinson and High 1974] [Rodriguez 1991] [Rom and Bober 1974] [Roschke 1955] [Roshko 1993] [Rubin 1971] [Rudy 1984] [Saint-Mard and Hendrick 1999] [Saltzman 1961] [Santho et al 2026] [Schadow and Chieze 1978] [Schetz et al 1980] [Schetz et al 1981] [Schiff and Sturek 1981] [Schmidt et al 2015] [Selby and Miandoab 1990] [Semaan and Nordhoff 2022] [Serdarevic-Kadic et al 2024] [Shaqarin et al 2021] [Shepard et al 2023] [Sher Afghan Khan et al. 2018] [Shmyglevskii 1966] [Shrewsbury 1968] [Sirignano and MacArt 2023] [Sisalah et al 2015] [Siva Krishna Reddy et al 2021] [Sivasubramanian et al 2006] [Sreekanth 1961] [Starr 1977] [Tagirov 1972] [Tanner 1972] [Tanner 1973] [Tanner 1975] [Tanner 1976] [Telli et al 2016] [Thompson and Smith 1982] [Tran 2020] [Tran et al 2017] [Tran et al 2019] [Tran et al 2025] [Tran et al 2025] [Tripathi et al 2015] [Venkatramanan et al 2021] [Virliani et al 2017] [Viswanath 1988] [Viswanath 1996] [Walpot et al 2011] [Washington et al 1968] [Whitfield and Potter 1966] [Whitmore and Moes 1999] [Whitmore et al 2001] [Whitmore et al 2005] [Wilcox and Chamberlin 1974] [Wilcox and Chamberlin 1975] [Wu and Kareem 2015] [Wu et al 2023] [Xia et al 2024] [Xue and Yu 2016] [Yang and Zha 2016] [Yang et al 2015] [Yang et al 2020] [Zarin 1965] [Zarin 1966] [Zhang et al 2024] [Zhou et al 2021] [Zhu and Morrison 2021] [Zumwalt and Tang 1963]

Of the 103 records in this cluster dating from 2015 or later, 22 name an aircraft, a missile, a projectile, a nozzle or another flight vehicle. The rest study generic bluff bodies, and with the 64 road vehicle records of the same years they are the current base-drag literature.

The X-24 and lifting-body vehicles

The vehicle and its family. The X-24A and X-24B, the PRIME entry vehicle that flew the shape first, the M2, HL-10 and HL-20 lifting bodies, and the later crew return and personnel launch designs that kept the shape.

236 records. [Adams et al 1973] [Aerothermodynamic design of a hypersonic lifting body including GPS navigation capability 1993] [Allen 2024] [Almosnino 2016] [Anderson et al 1963] [Anderson et al 1967] [Aradag et al 2007] [Armstrong 1977] [Bailey and Brownson 1979] [Banks and Fisher 2006] [Barret 1998] [Barret 1999] [Baumgartner and Elvin 1995] [Beam 1991] [Behr et al 2001] [Benson 2006] [Berry et al 1997] [Berry et al 2001] [Blair 1972] [Bosworth and Stachowiak 2005] [Boyden and McKinney 1968] [Boylan and Potter 1966] [Brunner et al 1966] [Bryson et al 1968] [Bugg and Sleeman 1967] [Campbell et al 1996] [Campbell et al 1996] [Campbell et al 1997] [Campbell et al 2004] [Carr and Lagimoniere 2013] [Chao et al 2010] [Chin 1970] [Collins et al 1970] [Colvin 2021] [Costa et al 2000] [Cruz and Ware 1992] [Cruz and Ware 1995] [Cruz et al 1989] [Stone et al 1991] [De Angelis and Tang 1969] [Delgado and Arcioni 2000] [Deng et al 2017] [Direct numerical simulations of hypersonic boundary layer transition over a hypersonic transition research vehicle model 2023] [Dutton 1993] [Dutton 1993] [Dutton 1994] [e-CRV - Design study of a European Crew Return Vehicle 2004] [Eldredge et al 1965] [Eliseev et al 2014] [Elliott 1968] [Erwin 1990] [Falarski and Mort 1969] [Falarski and Mort 1970] [Fasanella et al 2000] [Feigenbaum 1945] [First Glide Flight of Heavy Lifting Body Planned Soon 1966] [Freeman 1992] [Fuhrmann 2003] [Gafka and Daugherty 2000] [Gamse and Mort 1966] [Layton 1970] [Gentry 1972] [Gentry et al 1966] [Gibson and Goetz 1971] [Hassell 1960] [Haubelt et al 2001] [Hill and Ladson 1971] [HL-20 Personnel Launch System 1990] [Holmes 1970] [Holt et al 2016] [Hong 1999] [Hook and Freeman 1989] [Horvath et al 1990] [Horvath et al 2000] [Huang and Miele 1967] [Huffman and McKinney 1971] [Jackson and Cruz 1992] [Jackson and Rivers 1998] [Jackson et al 1991] [Jackson et al 1991] [Jackson et al 1992] [Jackson et al 1993] [Jackson et al 1993] [Jackson et al 1994] [Stevens et al 1966] [Jenkins et al 1968] [Jeong et al 2007] [Jeong et al 2009] [Jernell 1971] [Manke et al 1970] [Cochrane and Graham 1971] [McTigue 1970] [Pyle and Ash 1970] [Kaminsky and Johnson 1964] [Katz and Roglin 2000] [Kawato et al 2002] [Kawato et al 2003] [Kawato et al 2005] [Keener and Brownson 1972] [Kempel 1971] [Kempel and Manke 1974] [Kempel and Painter 1993] [Kempel and Thompson 1971] [Kempel et al 1971] [Kempel et al 1975] [Kempel et al 1994] [Khurana and Suzuki 2013] [Khurana et al 2012] [Kilgore and Davenport 1974] [Kock and Painter 1968] [Kock and Painter 1969] [Komerath et al 1998] [Kotfila and Painter 1969] [Krevor et al 2011] [Krevor et al 2011] [Kurita et al 2006] [Labbe et al 1999] [Lagimoniere and Avram 2024] [Larson 1972] [Layton and McTigue 1969] [Liu et al 2019] [Loomis et al 2004] [M2-F2 Lifting Body Accident Summary 1967] [Ma et al 2019] [MacConochie 2000] [Machin 2000] [Machin et al 1999] [Machin et al 2001] [Manke and Love 1975] [McTigue and Ryan 1968] [Merlin 2014] [Micol 1990] [Miele 1968] [Minami and Tsukamoto 2006] [Tang 1970] [Montella et al 2025] [Montella et al 2025] [Montella et al 2026] [Morino 1973] [Morio et al 2009] [Morris et al 1993] [Munday et al 2000] [Naeseth 1970] [Naftel and Talay 1993] [Nagy and Kirsten 1976] [Nietubicz 1975] [P.V and Laxman 2023] [Page and Anderson 1996] [Painter and Sitterle 1974] [Palmer et al 1994] [Palmer et al 1995] [Penland 1975] [Peterson 2004] [Petrov and Soudakov 2016] [Powell 1993] [Powell and Cruz 1991] [Pyle 1971] [Qi et al 2021] [Reed et al 1997] [Rana et al 2017] [Rasmussen 1978] [Reaser 1997] [Recasens et al 2005] [Reimann 2016] [Reller and Seegmiller 1960] [Rivers et al 1991] [Rizvi et al 2013] [Kempel et al 1970] [Ruf et al 1996] [Saccani 2020] [Sager 1995] [Saltzman et al 1999] [Saltzman et al 2002] [Saltzman et al 2007] [Scallion 1999] [Seegmiller 1968] [Shi et al 1969] [Shin et al 1999] [Shin et al 2001] [Sim 1973] [Sim 1973] [Sim 1976] [Smith 1965] [Smith et al 1990] [Smith et al 1998] [Soistmann and Spain 1993] [Spearman and Torres 1994] [Stadler 1993] [Stein 2005] [Stein et al 2005] [Stein et al 2007] [Stepner and Mehra 1974] [Stone and Piland 1991] [Stone and Piland 1993] [Strutz 1972] [Stubbs 1966] [Study of the influence of size of a manned lifting body entry vehicle on research potential and cost. Part II - Research 1967] [Sun et al 2026] [Talay 1992] [Talay 1992] [Talay and Stone 1991] [Tang 1971] [Tang and Pearson 1971] [Tang and Pearson 1973] [Tartabini et al 2000] [Taylor and Howard 2008] [Tendero Ventanas] [Wong et al 1958] [Thompson 1964] [Thompson 1966] [Thompson 1970] [Thompson 1970] [Trifoni and Lafferty 2025] [Trifoni et al 2026] [Vetter 1966] [Vidal 1974] [Viladegut 2018] [Viviani and Pezzella 2015] [Wacker et al 2001] [Ware 1989] [Ware 1989] [Ware and Cruz 1993] [Ware and Cruz 1993] [Ware et al 1991] [Warner and Wilcox 1972] [Wartemann et al 2018] [Weber et al 2000] [Weiland 2021] [Weilmuenster and Greene 1993] [Weilmuenster et al 1990] [Weilmuenster et al 1991] [Dana and Gentry 1970] [Wu 1984] [Wurster and Stone 1993] [Zhang et al 2019] [Zou et al 2026]

82 of these 236 records date from before 1976, the years in which the lifting bodies flew, and 9 titles name the X-24 or its SV-5 designation, while 89 name the HL-20, the X-38, a crew return vehicle or a personnel launch system, the designs that carried the shape after the programme ended.

Drag, performance and flight-determined aerodynamics

Drag in general, and how it is measured. Drag prediction and reduction, aircraft performance, Reynolds number effects, turbulence modelling, and the correlation of tunnel and flight.

218 records. [Adrian and Balachandar 2001] [Ahuja et al 2016] [Airbus Flies as “Wind Tunnel Model” 1988] [Aircraft performance monitoring from flight data 2015] [Aleisa et al 2023] [Aleisa et al 2024] [Anderson and Sutera 1965] [Anderson et al 2015] [Andrew and Cahn 1967] [Appa and Ausman 1997] [Appa et al 1998] [Awbi and Tan 1981] [Axelson and Hill 1981] [Aydın et al 2025] [Bader et al 2021] [Balatti et al 2021] [Ban et al 2018] [Bandyopadhyay 1989] [Bandyopadhyay and Gad-el-Hak 1994] [Barman and Erzberger 1976] [Bashkirov et al 2023] [Bell 1964] [Bellman 1959] [Bendarkar et al 2022] [Benedikt 1953] [Bergmann et al 2021] [Bert 1981] [Bogdanovic et al 1965] [Brasseur 1994] [Bull and Bridges 1985] [Camacho-Sánchez et al 2026] [Chang et al 2026] [Chen Yong et al 2015] [Cicala and Miele 1956] [Corsiglia et al 1981] [Crosthwait 1970] [Bushnell 1992] [Daforno 1982] [Fisher and Lanser 1994] [Davis 1968] [Dougherty 1975] [Dress 1989] [Ebrahimi et al 2024] [Edwards 1950] [Edwards 1950] [Edwards 1950] [Effect of Variations in weight or Normal Acceleration on the Ceiling of Jet-Propelled Aircraft, Correspondence 1955] [Eggers et al 1957] [Ehrenstein 2019] [Ellinwood 1967] [Ercan et al 2024] [Eshelby 1982] [Fawcett 1964] [Flight-test evaluation of engine power effects on lift and drag 1985] [Frost and Dill 1986] [Gaifullin 2023] [Gatti and Quadrio 2016] [Godwin et al 1964] [Goodyer and Kilgore 1973] [Grabe et al 2023] [Graham and Luskin 1946] [Greene 1988] [Greene 1989] [Grodzovskii 1968] [Haftmann et al 1988] [Hague 1981] [Haines 1968] [Hantrais-Gervois and Destarac 2015] [Harmon 1974] [Hedrick and Nichols 1975] [Hess and James 1975] [Hicks and Huckabine 1989] [Howell and Braslow 1955] [Jia et al 2021] [Jobe 1984] [Kaden and Luckner 2022] [Katoh et al 1989] [Katz et al 1982] [Kawasoe et al 2015] [Keskin 2026] [Kilgore and Dress 1984] [Kilgore et al 1974] [Kless et al 2012] [Knaus 1983] [Korsun et al 2024] [Kraiko and Shelomovskii 1984] [Kurkowski et al 1976] [Laine 1982] [Laitone 1978] [Laitone 1978] [Lara et al 2022] [Latham and Sorensen 1973] [Lee et al 2007] [Li 1960] [Li et al 2022] [Li et al 2022] [Liang 2024] [Lin 2025] [Lin and Ash 1986] [Liu and Stumpf 2018] [Liu and Yang 2024] [Loth et al 1976] [Lutze 1977] [Lyu and Liem 2020] [Ma 2025] [MACKlNNON and Madden 1972] [Macwilkinson et al 1974] [Macwilkinson et al 1974] [Magee and Taylor 1971] [Mazurov and Takovitskii 2022] [McKlNNEY and DOLLYHlGH 1971] [McVey et al 1969] [Mele 2022] [Menter et al 2022] [Messanelli et al 2019] [Metzger and Hedrick 1975] [Miele 1955] [Miele 1957] [Mineck 1995] [Morino and Kuo 1974] [Morris 1961] [Moser 1961] [Mount 1965] [Muchina 2020] [Mull and Algranti 1960] [Muller and Gasko 1967] [Myring 1976] [Nabae et al 2018] [Nabae et al 2025] [Nielsen 1985] [Nixon 1975] [Office Of Research Analyses Holloman Afb Nm 1963] [Ol 2007] [Olson 2015] [Ovcharenko and Poplavsky 2021] [Parkinson 1983] [Peng et al 2022] [Peterson et al 1980] [Petrie 1968] [Pfeifle et al 2022] [Pike 1977] [Pinebrook and Dalton 1983] [Pinebrook and Dalton 1983] [Pitkin 1968] [Potter and Whitfield 1957] [Ramaswamy and Schreyer 2022] [Rao 1983] [Reshotko 1979] [Ringel and Levin 1985] [Roberts 1963] [Rogers and Fasciano 2016] [Ruhland and Breitsamter 2023] [Ryu et al 2022] [Sachs 1980] [Saltzman and Ayers 1981] [Saltzman and Ayers 1982] [Saltzman et al 1956] [Saltzman et al 1994] [Sanders 1957] [Sanders 1965] [Sathish Kumar Sunnam et al. 2019] [Schmidt and Breuer 2015] [Schultz and Zagalsky 1972] [Sedney 1982] [Seginer and Salomon 1986] [Seraj and Martins 2025] [Shevell 1978] [Simos and Jenkinson 1985] [Smeltzer et al 1975] [Smith and Campbell 1996] [Smits 2007] [Smits 2009] [Sóbester 2021] [Spalart and Garbaruk 2021] [Specker 1985] [Springer 1998] [Squires 2004] [Sreenivasan 1987] [Steinhoff 2002] [Stephenson and Whitfield 1970] [Stollery and Murthy 1977] [Strand et al 1967] [Strand et al 1967] [Sun et al 2020] [Sutcliffe 1955] [Tamaki and Kawai 2024] [Tambor 1960] [Tenhave et al 2026] [Torenbeek and Wittenberg 1983] [Tucker 1990] [Vasil’ev 1966] [Vocke and Nunez 2016] [Vorburger et al 1986] [Wagner and Watson R. 1963] [Walsh 1990] [Walsh et al 1989] [Walvekar and Chakravarthy 2023] [Ward 1968] [Weiss and Giani 2024] [White 1977] [Whoric 1977] [Wolf 1996] [Woolf 2012] [Wu et al 2016] [Wu et al 2017] [Xia and Yu 1988] [Xu and West 1990] [Yajnik and Subbaiah 1976] [Yao et al 2019] [Yaravintelimath et al 2016] [Yarusevych and Kotsonis 2016] [Yurttav et al 2025] [Zaki 2014] [Zaprianov et al 1987] [Zhang et al 2025] [Zhao et al 2023] [Zheng et al 2026] [Панасюк et al 2018, Integral aerodynamic design of an]

Seven titles concern the correlation of tunnel and flight drag, the question that the X-24’s full-scale base drag answers in flight.

Flight control, stability and system identification

Making it flyable. Stability augmentation, flight control laws, envelope protection, and the identification of stability and control derivatives from flight data, which is how the X-24’s own derivatives were obtained.

187 records. [Abou-Hanna et al 1988] [Aerodynamic Analysis and Design Optimization of a Novel Flapping Wing Micro Air Vehicle in Hovering Flight 2023] [Air Force Flight Test Center Edwards Afb Ca 1974] [Air Force Flight Test Center Edwards Afb Ca 1974] [Ajaj 2021] [Albisser et al 2017] [Altunkaya et al 2024] [Anderson et al 1973] [Ayele et al 2024] [Bagherzadeh and Sabzehparvar 2015] [Bengtson et al 1975] [Beppu et al 1966] [Berci 2026] [Bie et al 2021] [Bird 1970] [Bird 1970] [Bird and McLarty 1970] [Black and Shadow 1967] [Bolton and Collins 1975] [Bond and Swanson 1953] [Bottasso and Montinari 2015] [Bowling and Key 1976] [Brandon and Morelli 2016] [Breuer et al 2022] [Breuhaus 1979] [Broussard and Stengel 1977] [Bunnell and Delany 1947] [Burken et al 2006] [Burris and Bender 1969] [Burris and Bender 1969] [Butler et al 1966] [Clark et al 1963] [Cliff and Lutze 1972] [Concorde Automatic Flight Control System 1971] [Conference on Aircraft Aerodynamics 1966] [Cotton 1974] [Curtiss 1971] [Da Ronch et al 2019] [de Visser and Pool 2023] [Dempster and Arnold 1969] [Dempster and Roger 1967] [Dias 2023] [Doko and Sasongko 2026] [Du 2024] [Edenborough 1968] [Efremov and Prodanik 2025] [Ellerbroek et al 2016] [Englar 1975] [Ferguson et al 1963] [Figliola 2004] [Figliola 2005] [Fletcher 1962] [Forkun et al 2020] [Fosdick 1970] [Gabrys et al 2019] [Gallagher et al 1972] [George et al 1967] [George et al 1969] [George et al 2022] [Gillis and Mitchell 1957] [Gilyard 1972] [Gilyard 1999] [Goland et al 1964] [Grahame 1969] [Grauer 2021] [Grauer and Morelli 2025] [Gregory et al 2011] [Griffith and Crosby 1970] [Walgemoed 2005] [Healey 1974] [Heersink et al 2022] [Henning 1959] [Rediess 1976] [Hiller Aircraft Corp Palo Alto Ca 1965] [Hofmann 1969] [Hofmann 1970] [Hrishikeshavan et al 2015] [Hsu et al 2024] [Hui and Chen 2023] [Ignatyev et al 2019] [Iliff 1977] [Iliff and Maine 1983] [Irwanto and Artono 2018] [Stewart 1992] [Grauer 2018] [Grauer 2020] [Grauer 2021] [Jianghao et al 2017] [Johnson and Weir 1969] [Johnson et al 1980] [Kawamura and Azimov 2022] [Kazemipour and Zhang 2025] [Keskar and Slater 1979] [Klein et al 1983] [Korsun et al 2018] [Kotitschke et al 2026] [Kumar and Ghosh 2023] [Kuttieri and Sinha 2023] [Lang et al 2025] [Lee et al 2017] [Lichota 2023] [Lichota et al 2017] [Lim et al 2020] [Lotze et al 1977] [Lu 2024] [Ma and Chen 2023] [Maine and Iliff 1979] [Mallery and Neebe 1966] [Manshadi and Saghafi 2018] [Mao and Zhao 1990] [Matt et al 2025] [McBrayer and Robinson 1965] [McGough et al 1974] [Menon et al 1989] [Metodiev 2024] [Mohamed and Dongare 2018] [Montgomery and Hatch 1969] [Mooij and van Gool 1978] [Moreira et al 2022] [Morelli and Cooper 2015] [Moszczynski et al 2026] [Muchmore 1988] [Mueller 1970] [Mulder 1977] [Muller 1967] [Murphy 1992] [Newell et al 1963] [O’hara 1971] [Obryan et al 1979] [Ogneru and Raileanu 2026] [Ogren et al 1974] [Okumoto and Elsanker 1973] [Osder et al 1976] [Painter and Sitterle 1972] [Pauli 1965] [Prosvirin and Kharchenko 2016] [Dhayalan et al 2018] [Rampy 1966] [Raz et al 1989] [Rodríguez de Cos and Acosta 2020] [Rothman and Chernoff 1961] [Saderla et al 2017] [Said Khoudiri 2025] [Sarah et al 2025] [Schieni et al 2024] [Schuet et al 2017] [Schumacher 1952] [Schwanz 1972] [Seibel 1963] [Shi 2025] [Shi et al 2023] [Shrivastava and Stengel 1989] [Simmons 2023] [Simmons et al 2023] [Simmons et al 2023] [Simmons et al 2023] [Singh Singh and Kanti Ghosh 2023] [Stengel 1980] [Suikat et al 1989] [Sun et al 2019] [Sun et al 2025] [Swaim 1970] [Taylor and Yoo 2011] [Tekles et al 2017] [Thornton 1993] [Tischler and Tobias 2016] [Van Baelen et al 2020] [van Rooyen and Eshelby 1981] [Velger and Shinar 1983] [Verma and Peyada 2020] [Wang et al 2022] [Wang et al 2022] [Wei et al 2020] [Weiser et al 2020] [Weisshaar 1978] [Wenqian et al 2016] [Whitaker and Rediess 1970] [Wolf 1971] [Xu et al 2022] [Yang et al 2018] [Ye et al 2015] [Yu et al 2022] [Yuan and Li 2019] [Yue et al 2025] [Zhang 2025] [Zhu and Duan 2015] [Завальная and Бурнашев 2015]

29 titles concern parameter estimation or system identification, the method of the X-24B’s derivative comparison, and 15 concern flight envelope protection, 15 of those from 2015 or later.

Landing gear, touchdown and landing loads

What the touchdown delivers to the structure. Landing gear design and dynamics, shock absorbers, touchdown and landing loads, shimmy, drop testing and the landing roll.

180 records. [Abu-Akeel 1969] [AEROSPACE LANDING GEAR SYSTEMS TERMINOLOGY] [Alexander 1959] [Allen et al 1962] [Allen et al 1963] [Anderson and Holmes 1966] [Anggoro 2021] [Arık and Bilgiç 2022] [Bagrov 2018] [Bagrov 2019] [Bakulin et al 2016] [Barfield 1968] [Batill 1982] [Black 1983] [Boroughs 1985] [Brown and Redwine 1948] [Burton 1981] [Cacciola and Calabria 2026] [Carden and McGehee 1983] [Carter et al 1997] [Castrichini et al 2018] [Chaloff et al 1974] [Chaudhary 2021] [Chen and Chen 2026] [Cheng et al 2021] [Chernenko and Burnashev 2022] [Collins and Black 1969] [Conway 1960] [Cooper et al 2005] [Crist and Symes 1981] [Darmawan et al 2025] [Dau et al 1965] [Daughetee 1974] [Davidson et al 1972] [De Martin et al 2022] [Delebarre 2019] [DeWispelare and Stager 1983] [Digges 1971] [Di̇nç 2021] [Douglas Aircraft Co Long Beach Ca 1962] [Durmuşoğlu 2026] [Durmuşoğlu and Yıldırım 2025] [Earl 1967] [Fairey Hydraulics Crashworthy Landing Gear for the Westland W30-300 Helicopter 1986] [Fallon et al 1999] [Feng et al 2015] [Feng et al 2025] [Fenwick 1966] [Fenwick 1967] [Fevralskikh 2021] [Foster 1952] [Frisby 1960] [Gan et al 2021] [Gannett and McLean 1964] [Gardinier and Taylor 1999] [Gatto 1983] [Goodall 1977] [Groomes 1964] [Hamilton et al 1980] [Han et al 2019] [Hasan 2024] [He 2018] [Hinchey and Sullivan 1982] [Hoare 1968] [Holmes et al 2016] [Horta et al 1999] [Howell et al 1990] [Hydraulics and landing gear 1971] [Jebáček and Horák 2016] [Jiang et al 2026] [Jobmann and Thielecke 2024] [Joyner 1969] [Joyner 1970] [Kansas Univ Lawrence 1952] [Khot et al 2025] [Kiefer et al 2016] [Kim and Costello 2016] [Kneeling landing gear 1973] [Knowles 2016] [Kocamer et al 2022] [Komov 2022] [Kordes and McKay 1962] [Kraft et al 1971] [Kranz 1954] [Krawczyk et al 2019] [Landing Area/Landing Gear Compatibility - A Brief History of SAE/Corps of Engineers Cooperation] [Landing gear 1973] [Landing gear 1974, Landing gear] [Landing gear 1974, Landing gear] [Landing Gear 1975] [Landing Gear 1986] [Landing Gear Alignment] [Landing Gear Ancillary Equipment 1968] [Landing Gear Stability] [Landing Gear System Development Plan] [Lee and Swegle 1963] [Lee et al 1973] [Leland and Thompson 1975] [Leoni 1983] [Li et al 2017] [Lindquist 1952] [Liu and Wang 2024] [Liu et al 2023] [Liu et al 2026] [Lloyd et al 1978] [Logan 1976] [Logan et al 1978] [Luong 2026] [Luong et al 2025] [Lystad 1975] [McComb and Tanner 1988] [McGehee 1985] [McGehee and Dreher 1982] [McKay and Noll 1967] [McPherson et al 1949] [Meng et al 2025] [Mennell 1976] [Meriwether and Harris 1962] [Modal Analysis of a Typical Landing Gear Oleo Strut 2018] [Morris and McGehee 1983] [Orlando 2020] [Padmanabhan and Dowell 2015] [Paletta et al 2015] [Paul et al 2019] [Pecora 2021] [Phillips et al 1973] [Pirooz and Fateh 2019] [Pirooz et al 2021] [Podruzhin and Zagidulin 2017] [Podruzhin et al 2021] [Pu 2015] [Pytka et al 2022] [Richards and Tate 2023] [RlDHA 1969] [Romero 2021] [Ross 1980] [Ruan et al 2024] [Schnitzer 1958] [Scholz et al 2026] [Sen 1990] [Sen 1990] [Sims and Schnitzer 1952] [Sivakumar and Syedhaleem 2018] [Sivakumar et al 2021] [Sivaramakrishnan 1981] [Skorupka 2024] [Some Current Types of Landing Gear 1968] [Stachiw et al 2021] [Stanisławski 2019] [Stauffer and Hoblit 1973] [King et al 1999] [Stolyarov and Jamal-Eddine 2023] [Stubbs 1963] [Sumerin and Shcheglov 2023] [Suszyński et al 2025] [Tanner 1990] [The Complete Landing Gear 1989] [Tian et al 2015] [Titov and Serebryansky 2026] [Toraldo et al 2023] [Trifonov et al 2024] [Veaux 1988] [Venkatesan 1977] [Venkatesan and Krishnan 1975] [Walker 1945] [Wang 2016] [Wang 2022] [Wang et al 2022] [Wei et al 2025] [Wood 1968] [Wu et al 2016] [Xie and Xu 2024] [Yang 1971] [Yang et al 2026] [Yin et al 2025] [Zhang 2024] [Zhang et al 2026] [Zhang et al 2026] [Zhicong and Voronko 2023] [Zhu et al 2025]

15 titles concern active, semi-active or magnetorheological gear and seven concern shimmy. The sink rate the gear must absorb is the subject of almost none, which Thin Subjects counts.

Entry and hypersonic flight of lifting vehicles

The flight the shape was drawn for. Lifting entry, hypersonic glide and the aerodynamics of blunt bodies at high Mach number, which a lifting body has to survive before it has a landing to make.

165 records. [Alexander 1978] [Alkamhawi et al 1990] [Allouche et al 2020] [An et al 2025] [Aprovitola et al 2021] [Arrington and Woods 1972] [Ashford 1965] [Balakrishnan et al 1997] [Balusamy et al 2024] [Banerjee 2019] [Bao et al 2021] [Baron and Efrat 1979] [Becker 1964] [Bell 1965] [Blanchard et al 1982] [Boeing Scientific Research Labs Seattle Wa 1963] [Bohn 1967] [Bonavita et al 2026] [Boylan 1965] [Brauckmann 1986] [Broglio 1961] [Bykerk et al 2020] [Bykerk et al 2020] [Cerimele et al 2017] [Clapp 1965] [Couch and Morris 1968] [Crogan 1961] [Cui et al 2023] [Deng 2026] [Deng and Zhao 2026] [Ding and Huang 2025] [Dong and Cai 2017] [Dong et al 2021] [Draper and Buck 1968] [Eghlima and Mansour 2017] [Engel and Putnam 2025] [Enmi et al 2018] [Fan and Huang 2021] [Fink 1966] [Fong et al 1970] [Freed 1963] [Gao 2023] [Gao et al 2015] [Gao et al 2018] [Gao et al 2026] [Geiger 1962] [Gibson et al 1989] [Goldberg 1966] [Gong et al 2020] [Guo et al 2023] [Guo et al 2024] [Han and Jiang 2018] [Hankey 1963] [Hollis and Hollingsworth 2012] [Hsu et al 1990] [Huang 1968] [Huang and Chang 2025] [Huang and Yao 2019] [Hunter et al 1986] [Hwang et al 2026] [Joarder 2018] [Johnson et al 1982] [Johnson et al 2018] [Johnson et al 2018] [Kanwar 2024] [Karlgaard and “O’Farrell 2022] [Karlgaard et al 2019] [Kelley et al 1982] [Kenyon 1961] [Kilgore and Davenport 1975] [Knight and Naiman 2009] [Kumar and Mahulikar 2017] [Kumar et al 2018] [Levy 1969] [Li et al 2010] [Li et al 2012] [Li et al 2016] [Li et al 2021] [Liechty et al 2002] [Liu and Shen 2015] [Lobbia 2017] [Luo et al 2026] [Lusty and Miele 1966] [Ma et al 2025] [Mageed Mahmoud et al 2016] [Masaki and Yakura 1968] [Mitcheltree et al 1999] [Mooij and Hanninen 2009] [Narayana and Selvaraj 2023] [Ni et al 2024] [Niu et al 2018] [Non-Contact Measuring Section in the Problem of Hypersonic Aerodynamics 2019] [Ortloff 1968] [Otsu 2016] [Otsu 2018] [Pan et al 2024] [Penland and Romeo 1971] [Penland et al 1978] [Perminov 1969] [Pezzella and Viviani 2024] [Pfaff 1968] [Pham and Nguyen 2025] [Pham et al 2020] [Qiu et al 2016] [Rana et al 2017] [Raney and Lallman 1991] [Rataczak et al 2024] [Reed 2005] [Reed 2006] [Reggiori 1971] [Riggins and Camberos 2020] [Rizvi et al 2017] [Rodi and Bennett 2012] [Sai Madhuri et al 2021] [Santos 2011] [Sarwar et al 2025] [Savage and Tinling 1959] [Sánchez Muñoz et al 2024] [Schneider 2009] [Seager and Agarwal 2017] [Sharenson 1966] [Shimada and Ohwada 2020] [Sims and Hahn 1964] [Sostaric et al 2019] [Dutta et al] [Spearman 1984] [Stern and Chu 1963] [Su et al 2024] [Sun et al 2026] [Wan and Cm 2017] [Takahashi et al 2015] [Tang et al 1978] [Tanno and Tanno 2021] [Tao et al 2016] [Tekure et al 2021] [Terasaki 1963] [Thomas and Perlbachs 1967] [Thompson and Hull 1970] [Townend 1979] [Vasil’evskii et al 2017] [Viviani et al 2020] [Wang 1963] [Wang and Ting 1961] [Wang and Zhang 2022] [Wang et al 2020] [Wang et al 2022] [Wang et al 2023] [Weidner et al 1976] [Whitmore et al 1994] [Xiao et al 2020] [Yadav et al 2018] [Yang et al 2016] [Ye 2015] [Yoon and Suzuki 2024] [Yu et al 2016] [Zhai and Yang 2020] [Zhang 1992] [Zhang et al 2017] [Zhang et al 2019] [Zhang et al 2022] [Zhang et al 2025] [Zhong et al 2019] [Zhou et al 2019] [Zhu 2022] [Zuppardi 2021]

19 titles concern hypersonic glide or boost-glide vehicles and 25 concern spikes, aerodisks or counterflowing jets on blunt bodies, which is forebody drag rather than the base drag of a lifting body.

Propulsive and planetary landing

The alternative the article sets against the flare. Propulsive landing of rocket stages and the powered descent of lunar, Martian and asteroid landers, which meet the touchdown with energy added rather than spent.

136 records. [A Minimum Fuel Vertical Touchdown Lunar Landing Guidance Technique 1964] [Abdhul Rahuman and Lee 2026] [Afanas’ev et al 2018] [Agarwalla 2025] [Allard 2024] [Anderson et al 2024] [Korzun et al] [Korzun and Chambers] [Bagal 2026] [Baraldi and Conte 2023] [Bentley 2009] [Mahajan 2024] [Bojun et al 2019] [Botelho et al 2022] [Buchnev and Danilov 2026] [Carradori et al 2026] [Chai et al 2020] [Cheatham and Hackler 1966] [Chen et al 2019] [Chen et al 2025] [Chen et al 2026] [Choo et al 2018] [Coleman and Davis 2004] [Condoleo and Theil 2018] [Çelik and Demirezen 2024] [Çelik and Sánchez 2017] [Donahue 1997] [Dong et al 2023] [Eren et al 2015] [Federici et al 2026] [Franklin and Stortz 1993] [Furfaro et al 2020] [Gallaher et al 1996] [Gautam et al 2018] [Guadagnini et al 2023] [Han et al 2024] [Huang 2019] [Huang and Zhang 2026] [Munoz-Burgos et al 2026] [Jaquet and Riley 1964] [Jeon et al 2022] [Johnson et al 2020] [Munoz-Burgos and McDonough] [Munoz-Burgos et al 2025] [Ju et al 2022] [Jung and Bang 2015] [Kim et al 2021] [Kim et al 2021] [Konstantinidis and Förstner 2020] [Korzun et al 2020] [Krishnan and Sajikumar 2023] [Kulumani and Lee 2022] [Lee 2011] [Lee et al 2025] [Lee et al 2026] [Lei et al 2022] [Leparoux et al 2022] [Li et al 2021] [Li et al 2024] [Li et al 2024] [Li et al 2025] [Li et al 2025] [Liang et al 2022] [Liu 2019] [Liu et al 2022] [Long et al 2022] [Lorenz 2015] [Lunar landing rehearsal 1969] [Lunghi et al 2022] [Kramer et al] [Ma et al 2017] [Ma et al 2018] [Ma et al 2018] [Maass et al 2020] [Marwege and Gülhan 2023] [Merrem et al 2020] [Mustafa and Shofiqul 2016] [Naftel and Powell 1993] [Park et al 2019] [Pavlov and Simakova 2021] [Pierrottet et al 2014] [Purcell et al 2025] [Bailey et al 2025] [Response Analysis of Landing Leg Deployment and Landing Transient Impact of Reusable Launch Vehicle 2026] [Reusable Launch Vehicle Landing Gear Mechanism Technologies A Review 2026] [Roithmayr and Pei 2024] [Ryu et al 2025] [Sagliano 2018] [Sagliano 2019] [Sanchez et al 2018] [Saprykin 2020] [Sasaki et al 2025] [Scorsoglio et al 2022] [Sickles and Lawrence 1991] [T A Clark et al] [Tang and Gong 2023] [Thies 2022] [Tian et al 2018] [Tomita et al 2022] [Utkarsh R. Moholkar 2025] [Vassilakos et al 2011] [Walton et al 1964] [Wan et al 2026] [Wang et al 2019] [Wang et al 2020] [Wang et al 2020] [Wang et al 2022] [Wang et al 2024] [Wang et al 2024] [Wang et al 2024] [Wibben and Furfaro 2016] [Williamson Jr. 1963] [Witte et al 2016] [Wolf et al 2011] [Xing et al 2024] [Xiong et al 2022] [Xiu et al 2024] [Xu 2005] [Xu et al 2016] [Xu et al 2017] [Yang et al 2024] [Yu et al 2023] [Yue et al 2018] [Yue et al 2018] [Yue et al 2019] [Yue et al 2022] [Yue et al 2022] [Zewge and Bang 2023] [Zhang et al 2015] [Zhang et al 2018] [Zhang et al 2019] [Zhang et al 2019] [Zhang et al 2021] [Zhao et al 2020] [Zheng et al 2017] [Zhu et al 2026]

59 of these 136 titles concern the Moon, Mars, Venus, an asteroid or another planetary body, and 54 name a rocket, a booster or a launcher. 113 date from 2015 or later.

Flight test practice and research aircraft

The practice of flight research. Flight test technique and instrumentation, and the research aircraft programmes and test centres that flew them.

81 records. [Adelgren et al 2004] [Advisory Group for Aerospace Research and Development 1984] [Air Force Flight Test Center Edwards Afb Ca 1970] [Air Force Flight Test Center Edwards Afb Ca 1995] [Air Force Flight Test Center Edwards Afb Ca 2002] [Air Force Flight Test Center Edwards Afb Ca 2002] [Air Force Test Pilot School Edwards Afb Ca 1990] [Air Force Test Pilot School Edwards Afb Ca 1990] [Air Force Test Pilot School Edwards Afb Ca 1993] [American Institute of Aeronautics and Astronautics 1992] [Arenson et al 1955] [Arif and Sasongko 2021] [Bach 1982] [Bell and Strock 1980] [Burcham et al 1997] [Carico 1998] [Che et al 2021] [Chevalier 1973] [Clark and Walters 1986] [Cohan and Hirsh 1966] [Coombe 1970] [Dean and Mena 1983] [Deckert and Holzhauser 1973] [Duke and Jones 1984] [Edwards 1983] [Ennix-Sandhu 2006] [Fisher 1999] [Fisher 2007] [Fisher and Parcel 2007] [Flight Test Programme 1970, Flight Test Programme] [Flight Testing 1992] [Flight Trials and Testing 1965] [Gorn 2003] [Hashii and Thompson 2018] [Hillje and Tymms 1978] [Irvine 1968] [Lux-Baumann and Burkes 2005] [Judge and Cummings 1966] [Kannan et al] [Kannan et al] [Kehoe 1987] [Kehoe 1988] [Kidd 1966] [Kim et al 2019] [Ko and Schuster 1983] [Ko and Schuster 1984] [Kohlman 1979] [Korsun and Moung Htang 2023] [Korsun et al 2017] [Liu and Zhao 2026] [Lockenour and Layton 1976] [Lockheed-Georgia Co Marietta 1969] [Lofthouse and Cummings 2017] [Lokos et al 2015] [Lucka and Michael 1999] [Matranga 1961] [Monstein et al 2019] [Nicholson and lowry 1966] [Nicolaides 1976] [Norton 1990] [Obermark 2004] [Painter 1983] [Painter and Erickson 1984] [Pepper 1969] [Pittsburgh Univ Washington Dc Research Staff 1966] [Borek and Pool 1994] [Roger et al 1975] [Schwartz and Wray 1969] [Stange 1959] [Stottier 1995] [Tangler 1979] [Temple 2006] [Tomaszewski and Goraj 2019] [Turk and Watts 1964] [Turk and Watts 1965] [Vagianos and Rooney 1964] [Van Gaasbeek 1980] [Wolkovitch 1984] [Yasue 2020] [Yechout 1988] [Zajdel et al 2022]

22 of the 81 date from before 1976.

Road vehicle drag

The same physics in a different medium. The drag of lorries, cars, trains and platoons, whose blunt bases and wakes are the X-24’s problem at a lower speed.

68 records. [AERODYNAMIC ANALYSIS OF THE VEHICLE USING THE SOLID WORK FLOW SIMULATION 2018] [Aerodynamic Analysis of Vehicle Using CFD 2017] [Aerodynamic Drag Improvements on a Simplified Heavy Vehicle using Three-sided Plain and Notched Base Flaps 2023] [Aulakh 2017] [Baek and Lee 2019] [Bao et al 2022] [Buckley and Marks 1978] [Che et al 2023] [Cui et al 2015] [Cui et al 2023] [Dinul et al 2025] [Dzhandzhgava et al 2019] [EFFECT OF VARIOUS AERODYNAMIC DRAG REDUCTION METHODS ON VEHICLE- A REVIEW 2017] [Gao et al 2022] [Haffner et al 2022] [Hasen et al 2020] [Her et al 2016] [Holt et al 2015] [Hossen and Saeedi 2026] [INVESTIGATION OF MODIFIED PROFILE OF HEAVY COMMERCIAL VEHICLE TO PRUNE AERODYNAMIC DRAG 2015] [Jaffar et al 2020] [Ji et al 2026] [Josefsson et al 2024] [Kaneko et al 2025] [Kapote 2024] [khosravi et al 2015] [Kim and Kim 2026] [Kim et al 2020] [Kim et al 2021] [Kohama and Yoon] [Kothari 2021] [Kwon 2017] [Lee and Lee 2017] [Liang et al 2024] [Liu et al 2026] [Mamo and Gopal 2023] [Markina et al 2020] [Marks and Buckley 1978] [Mohrfeld-Halterman and Uddin 2016] [Mohrfeld-Halterman and Uddin 2016] [Mosiężny et al 2020] [Numerical study of aerodynamics drag and flow characteristics of the high-speed train head design 2024] [Palanivendhan et al 2021] [Pan 2025] [Pavia et al 2019] [Pedigree Aerodynamic Shape Design of High-Speed Trains 2023] [Peiró Frasquet et al 2023] [Peterson and Sandlin 1981] [Phan et al 2024] [Prabhu et al 2025] [Sarker et al 2024] [Shakti et al 2017] [Shimizu et al 2019] [Tadakuma et al 2016] [Tang and Wang 2017] [Tang and Yang 2025] [Tilvaldyev et al 2021] [Vernet et al 2018] [Wang 2017] [Wang et al 2020] [Xu et al 2022] [Yan et al 2018] [Yang 2021] [Yang et al 2021] [Yang et al 2023] [Yildiz and Dandil 2018] [Zhang 2024] [Zhao et al 2025]

64 of the 68 date from 2015 or later, and 20 name a truck, a lorry or a heavy vehicle.

The standard atmosphere

The medium. Standard and model atmospheres and high-altitude density, which supply the density at Edwards that every flight condition in this article uses.

18 records. [Air Force Test Pilot School Edwards Afb Ca 1962] [Blish 1980] [Brombacher 1926] [Brombacher 1935] [Dennis P. Dykstra 1980] [Ghosh 1970] [Justh 2022] [Minzner 1967] [Minzner et al 1976] [Mueller 1982] [Peters 1977] [Pisharoty 1959] [Standard Atmosphere - Tables 1955] [Sterne 1958] [U.S. Standard Atmosphere Supplements 1966, U.S. Standard Atmosphere Suppleme] [U.S. Standard Atmosphere, 1962] [Webster 1947] [Zuppardo 1993]

Other aeronautical literature

The residual, reported and not hidden. On-subject aeronautical work that belongs to no cluster above, mostly flight loads and gusts, flutter, and rotorcraft and vertical takeoff research aircraft. No further subject in it is large enough to name, and dividing it further would describe the filing rather than the field.

29 records. [Anderson et al 1959] [Austin and William H. 1967] [Baum 1956] [Bennett and Abel 1982] [Brown 1950] [Cea and Palacios 2023] [Dempster and Bell 1965] [Deveaux 1965] [Ferrell et al 1974] [General Electric Co Cincinnati Oh 1964] [Haber 1952] [Hirsh 1965] [Keribayeva et al 2022] [Koenig and Brady 1960] [Lee 1985] [Luderer and Thielecke 2025] [Macmillan 1950] [Magee and Taylor 1971] [Mayer and Hamer 1961] [McDonnell Aircraft Corp St Louis Mo 1950] [Rokhsaz and Kliment 2017] [Shevloff and Reid 1953] [Snyder 1950] [Sudha et al 2018] [Supersonic Cruise Research 1979 1980] [Swaim and Connor 1968] [Whitener 1979] [Wrestler and Clifton G. 1965] [Zosimovych 2022]

Where the Framing Breaks Down

Treating the X-24 through its landing gets three things wrong.

The vehicles were not landing demonstrators. They were transonic and low-supersonic research aircraft that happened to land without engines because that is how they were flown. The X-24B reached 1,164 miles an hour, and a great deal of the flight record is about stability and control at speeds that have nothing to do with the approach.

The base drag analysis is retrospective. Saltzman, Wang and Iliff published in the 1990s and 2000s, in Saltzman et al 1999, Saltzman et al 2002 and Saltzman et al 2007, drawing on flight data gathered decades earlier. Nobody sized the X-24B using the factor of three derived above. The relation explains the vehicle rather than having produced it, and this article should not be read as a reconstruction of the design process.

The flare corridor is computed from a point-mass energy model, with a constant load factor and a drag polar that is a parabola. A real flare has neither. The agreement to nine percent is encouraging and is not a validation.

There is a fourth, about attribution. Two concrete landings do not by themselves settle a design decision as large as deleting an orbiter’s engines. They were one input among many, and the article’s account of the causal chain leans on a programme retrospective rather than on the decision record.

The Source Base

The research literature here is drawn from the NASA Technical Reports Server, from Defense Technical Information Center records reached through their registered identifiers, and from the Crossref index. The research survey holds 2,851 research records, counting the definitions in the Research list of the References, of which 946 are report primaries, being 33.2 percent, by the identifier rule set out under The Definition of Primary. The median publication year is 1999. Of the 2,810 dated records, 712 were published before 1976, the period in which the lifting bodies flew, being 25.3 percent, and 1,187 were published in 2015 or later, being 42.2 percent.

The survey holds 9 records whose titles name the X-24 or its SV-5 designation, 8 of them report primaries. Most are the programme’s own record, from the full-scale tunnel tests of the X-24A to the X-24B’s flight test reports.

This article and the X-23 article share a vehicle family and only a minority of their literature, because entry mechanics at Mach 25 and unpowered landing at Mach 0.5 are different subjects with different vocabularies.

The Definition of Primary

Primacy is a property of the document, and this survey derives it from the identifier. A record is a report primary when its address is on the NASA Technical Reports Server or it carries a digital object identifier under the 10.21236 prefix, which Crossref registers for Defense Technical Information Center reports. The reports this article’s argument rests on are report primaries under that rule, among them Larson’s landing statistics, the flight-determined lift and drag of Saltzman, Wang and Iliff, Dana and Gentry’s account of the approach, and Manke and Love’s report of the X-24B programme. The rule does not reach the journal papers among the foundational sources, such as Hoerner on base drag and thick trailing edges, so 33.2 percent is a lower bound on how much of the survey is first-hand.

Thin Subjects

Seven subjects that this article’s derivations depend on have thin literatures. Each count below is the number of research records in this survey whose title carries at least one of the listed terms, with a hyphen read as a space. Where a row joins two groups of terms with the word together, a title must carry a term from each group.

Subject	Title terms counted	Records
the landing flare	flare, flares, flare out, flared landing, flaring	37
the trade between forebody drag and base drag	forebody, fore body together with base, afterbody, boattail, boat tail	2
touchdown sink rate	sink rate, sink rates, sink speed, sinking speed, rate of descent, descent rate, vertical velocity	2
the energy management of an unpowered approach	energy management, energy height, energy state, terminal area energy	37
the float after the flare	float, floating, floats together with landing, flare, touchdown	0
the span efficiency of a low aspect ratio shape	oswald, span efficiency, efficiency factor, induced drag factor	2
the drag of an ablated or roughened heat shield	ablated, ablative, ablation, roughness, roughened together with drag, lift to drag	3

The flare is studied mostly as a control and piloting task. Of the 37 titles that name it, 11 concern automatic flare, flare control laws or guidance, and most of the rest concern piloted technique, displays and visual cues. Two relate the flare to the lift-to-drag ratio, a 1949 analysis of lift-drag ratio and stalling speed and a 1968 study of flare requirements for glide vehicles of low lift-to-drag ratio, and they are the nearest the literature comes to the corridor derived here from energy.

The forebody and base drag trade is the article’s own analysis. Two titles name the forebody together with the base or the afterbody, so the factor of three at the optimum rests on Hoerner’s relation and on Saltzman, Wang and Iliff’s flight data rather than on a literature of the trade.

The sink rate at touchdown is almost never the subject of a title, which agrees with Larson’s statement that the lifting bodies’ vertical velocity at touchdown was not instrumented. Two titles carry the terms.

Energy management is a reentry and orbiter subject. Of the 37 titles that name it, 19 concern the Shuttle, a reusable or entry vehicle, a boost-glide vehicle or an unpowered glide.

The float, the span efficiency of a lifting body and the drag of a roughened heat shield have almost no titles of their own, so the float after a 1.5 g flare, the Oswald factor of 0.6 and the roughness penalty at landing rest on the documents cited where they are derived.

What the Survey Admits

A record is admitted only when a person reading its title finds it on this article’s subject. A record that shares a word with the subject and nothing else is excluded.

The vocabulary of this subject belongs to other fields more than to aeronautics, and three cases are severe. Flare is overwhelmingly the solar flare, and secondarily the gas flare and the flare stack of petrochemical engineering. Energy management belongs to power grids, buildings and batteries, and in the report archives it names, among much else, a manual on energy conservation in Navy family housing. Base is the air base, the database and the base station, and survives here only because base drag carries its own disambiguating word.

Much of the Space Shuttle’s literature is not about flying it. Titles naming the Shuttle or its orbiter also cover communications, payload experiments, launch-site operations, waste handling and materials, and only those on its aerodynamics, entry, approach, landing and handling are admitted. Approach, landing and terminal area also name air traffic scheduling and airspace operations, lifting-surface theory also names turbomachinery cascades, and drag also names ships, hydrofoils, ordnance and spheres in creeping flow, and these are excluded.

Other records that share a word with the subject and nothing else are excluded as well. They include multi-criteria decision studies that match approach and criteria, combustion studies of flames held behind bluff bodies, road and ground vehicle dynamics, economics and management papers including three on an economic hard landing, particle and Stokes-flow mechanics, marine and ocean engineering, space plasma and planetary papers with no landing in them, energy and chemistry papers, studies of landing in sport and human biomechanics, medical simulators, pyrotechnic illumination flares, solar flares, and studies of pigeons, honeybees, a cormorant and insect flight. Correction, erratum, clarification, retraction and withdrawal notices, figure, table and supplementary-material records, peer-review reports and journal front matter are also excluded, because a survey counts research works and these are parts of works or editorial events. Book reviews, dictionary and other short reference entries, news items and meeting notices are excluded for the same reason, and so is a second deposit of a document already counted, such as an abstract-journal or reprint listing, a preprint or a set of presentation slides beside the paper itself.

Three families that a shared exclusion list refuses elsewhere are admitted here because they are this subject, namely hypersonic and reentry vehicles, because a lifting body is an entry shape, head-up displays for the approach, which belong to the handling qualities literature, and road vehicle drag, which is where the base-drag physics now lives.

Some records of doubtful relevance are kept, 121 in all. Boattails of artillery shells and bullets are kept because a projectile base is a blunt base. Cylinder and bluff-body wakes from wind engineering are kept for the wake physics, rotorcraft stability and the handling qualities of spacecraft docking for their methods, and a study of body and feather drag in a peregrine falcon for its drag measurement. A reader may weigh each accordingly.

Every research title has been read for relevance, so the off-topic share that remains is a matter of reading judgement. A reading of titles cannot show that a work is relevant in substance, so this is a statement about titles only.

Epistemic State

Historical fact, as reported by the accessible record. The X-24A flew 28 times between 17 April 1969 and 4 June 1971, 18 of them under power, reaching Mach 1.60 and 71,400 feet. It was rebuilt as the X-24B, which flew 36 times between 1 August 1973 and 26 November 1975, 24 of them under power, reaching Mach 1.752, or 1,164 miles an hour, and 74,100 feet. These figures are from the flight log printed by Reed. On 5 and 20 August 1975 John Manke and Michael Love landed the X-24B on the main concrete runway at Edwards, Manke at a planned mark 5,000 feet along it. The approach technique, a flare of about 1.5 g from 1,000 feet to level flight at 100 feet followed by a float, is documented by Dana and Gentry for the lifting bodies of 1970, and the Flight Research Center’s case for flying an orbiter unpowered was published in the same year. The X-24A is the vehicle for which X-23A was requested in November 1965 and refused in December, and which received X-24A in 1967.

Flight-determined data taken from a published source. The dimensions, wetted areas, base areas and weights in the vehicle table are from Saltzman, Wang and Iliff, as is the finding that full-scale base drag requires a Hoerner coefficient near 0.10 against the model-scale 0.029, the pair of optimum coefficients 0.1284 and 0.3852, and the measured tailcone-on lift-to-drag ratio of 7.5 for the Enterprise. The flight-measured maximum lift-to-drag ratios by trim are from the same authors’ 2002 assessment. The X-24A’s touchdown airspeeds, impact load factors and miss distances are from Larson’s tables, and the means and spreads quoted for them are computed here from those tables. The X-24B’s derivative comparison is Sim’s.

Engineering analysis, performed here and checkable. The drag bucket and its differentiation, the result that total drag is three times forebody drag at the optimum, the cancellation of reference area from the lift-to-drag expression, the predicted lift-to-drag ratios for all seven vehicles, the square-root-of-three tailcone prediction, the approach angle and sink rate, the integrated flare, the load factor solved from the quoted touchdown speed, the corridor bounds, the energy accounting, the float after a 1.5 g flare, the matched comparison with the flight-measured lift-to-drag ratios, the thrust a shallower glide slope would need, the effect of ablated roughness, and the statistics computed from Larson’s landing tables are all derived in this article from stated assumptions or cited tables.

Inference, and flagged as such. That the X-24B approached in a high-base-area trim is inferred from the fact that the resulting lift-to-drag ratio reproduces the documented flare height at the documented load factor, not from a stated flap setting, and the documented landing configuration of the X-24A had its upper flaps closed, with speed brakes available. The 1.19 g solved from the quoted touchdown speed describes a flare ended on the runway, which the documented technique contradicts, so it is retained as a property of the model and not as a statement of what was flown. That the X-24B’s concrete landings followed the documented 1970 technique is inferred from its being the programme’s pattern, not stated for those flights. That the two concrete landings caused the deletion of the orbiter’s air-breathing engines follows a programme retrospective and is not established from the decision record.

Assumptions that everything downstream inherits. The Oswald efficiency factor of 0.6 is taken from the source’s comparison curve. The flare load factor is not chosen but solved from the quoted touchdown speed, and the table shows what other choices give. The approach speed of 300 miles an hour is assumed and lies below the documented band of 270 to 300 knots indicated. The drag polar is parabolic, the flare is flown at constant load factor, and the vehicle is a point mass throughout.

What the record does not settle. The actual trim and base area on the X-24B’s approaches, and its final-approach speed. The actual load factor flown in its flare. The touchdown speeds and miss distances of the two concrete landings, which are not in the documents read here, and touchdown sink rates for any of the lifting bodies, which Larson states were not instrumented. The base pressures below Mach 0.8, which Saltzman, Wang and Iliff estimated rather than measured. The growth in span from the X-24A to the X-24B, on which the histories and the flight-determined table disagree. The date of the decision to delete the orbiter’s air-breathing engines, and so the weight of the X-24B’s landings in it relative to the case the Flight Research Center had made in 1970. Several Air Force Flight Test Center reports, among them the X-24B flight planning and conduct report and the flight test and wind tunnel performance comparisons for both vehicles, were not retrievable from the Defense Technical Information Center for this article.

Out of Scope

The detailed stability and control derivatives of both vehicles beyond the comparisons summarised here. The M2 and HL-10 programmes, which have their own histories and are covered in Jenkins, Landis and Miller. The XLR-11 engine, which the X-1 article covers. The Space Shuttle Approach and Landing Tests as a programme. Lifting-body structural design and the structural detail of the rebuild that turned the A into the B. The full decision record on the orbiter’s air-breathing engines.

Conclusion

A blunt base costs a factor of the square root of three in lift-to-drag ratio, and everything difficult about landing an X-24 follows from that one number.

Three instead of five means an eighteen-degree glide instead of eleven. It means approaching sixty percent faster than best glide, on purpose, because the flare needs the energy. It means beginning that flare a thousand feet up rather than thirty, and it means a corridor a few tenths of a g wide with running out of speed on one side and floating off the far end of the runway on the other.

The X-24B flew through the middle of that corridor onto fifteen thousand feet of concrete, twice, and an orbiter that had been designed with jet engines for its landing approach flew without them.

References

Books

• Hoerner’s compendium of drag data
• Jenkins, Landis and Miller
• Reed’s account of the lifting bodies

Reference

• 14 CFR 25.473, Landing Load Conditions and Assumptions
• Boeing X-37
• Buran
• Cochrane and Graham, Pilot Safety for the X-24A Lifting Body Vehicle, 1971
• Edwards Air Force Base
• Falarski and Mort, Full-Scale Wind-Tunnel Investigation of the Aerodynamic Characteristics of the X-24A Lifting Body Aircraft, NASA TN D-5932, 1970
• Falcon 9
• Hallion, On the Frontier, Flight Research at Dryden 1946-1981, NASA SP-4303, 1984
• John Manke and Michael Love
• Martin Marietta X-24B
• Parsch, Missing USAF and DOD Aircraft Designations
• Saltzman and Meyer, A Reassessment of Heavy-Duty Truck Aerodynamic Design Features and Priorities, NASA/TP-1999-206574, 1999
• Sim, A Correlation Between Flight-Determined Derivatives and Wind-Tunnel Data for the X-24B Research Aircraft, NASA TM-113084, 1997

Related Post

• X-1
• X-10
• X-11
• X-12
• X-13
• X-14
• X-15
• X-16
• X-17
• X-18
• X-19
• X-2
• X-20
• X-21
• X-22
• X-23
• X-3
• X-4
• X-5
• X-6
• X-7
• X-8
• X-9
• X-Planes series

Research

• 180 Fault Tolerant navigation system for aircraft landing 1994
• 2018, ISRO Releases the Special Issue o
• A Minimum Fuel Vertical Touchdown Lunar Landing Guidance Technique 1964
• A Spreadsheet Tool for the AERODAS Model for Calculating Airfoil Pre-Stall and Post-Stall Lift and Drag Characteristics 2018
• Abdhul Rahuman and Lee 2026
• Abou-Hanna et al 1988
• Abu-Akeel 1969
• Ackerman et al 2017
• Adams and Hatch 1971
• Adams et al 1973
• Addy 1969
• Addy 1970
• Adelgren et al 2004
• Adrian and Balachandar 2001
• Advisory Group for Aerospace Research and Development 1984
• Aerodynamic Analysis and Design Optimization of a Novel Flapping Wing Micro Air Vehicle in Hovering Flight 2023
• AERODYNAMIC ANALYSIS OF THE VEHICLE USING THE SOLID WORK FLOW SIMULATION 2018
• Aerodynamic Analysis of Vehicle Using CFD 2017
• Aerodynamic and Landing Measurements 1960
• Aerodynamic Drag Improvements on a Simplified Heavy Vehicle using Three-sided Plain and Notched Base Flaps 2023
• Aerodynamic Performance Enhancement of Low Aspect Ratio Military Drone Aircraft Wing through Employing Leading Edge Tubercles 2024
• AEROSPACE LANDING GEAR SYSTEMS TERMINOLOGY
• Aerothermodynamic design of a hypersonic lifting body including GPS navigation capability 1993
• Aerothermodynamic Entry Environment of the Space Shuttle Orbiter 1983
• Afanas’ev et al 2018
• Agarwalla 2025
• Ahmed and Wyatt 2024
• Ahuja et al 2016
• Ailor and Eberle 1976
• Air Force Flight Test Center Edwards Afb Ca 1970
• Air Force Flight Test Center Edwards Afb Ca 1974
• Air Force Flight Test Center Edwards Afb Ca 1974
• Air Force Flight Test Center Edwards Afb Ca 1995
• Air Force Flight Test Center Edwards Afb Ca 2002
• Air Force Flight Test Center Edwards Afb Ca 2002
• Air Force Test Pilot School Edwards Afb Ca 1962
• Air Force Test Pilot School Edwards Afb Ca 1969
• Air Force Test Pilot School Edwards Afb Ca 1990
• Air Force Test Pilot School Edwards Afb Ca 1990
• Air Force Test Pilot School Edwards Afb Ca 1990
• Air Force Test Pilot School Edwards Afb Ca 1991
• Air Force Test Pilot School Edwards Afb Ca 1992
• Air Force Test Pilot School Edwards Afb Ca 1993
• Airbus Flies as “Wind Tunnel Model” 1988
• Aircraft Landing Measurement System 1971
• Aircraft performance monitoring from flight data 2015
• Ajaj 2021
• Akametalu et al 2018
• Al Bakri
• AL-Bakri and Kluever 2017
• Al-Bakri et al 2020
• Alatorre et al 2022
• Albisser et al 2017
• Aleisa et al 2023
• Aleisa et al 2024
• Alexander 1959
• Alexander 1971
• Alexander 1978
• Alexander and Camp 1983
• Ali Ahmed and Saleh 2019
• Alkamhawi et al 1990
• Allard 2024
• Allen 2024
• Allen et al 1962
• Allen et al 1963
• Allen et al 1994
• Allouche et al 2020
• Almosnino 2016
• Altunkaya et al 2024
• Aman Prakash et al 2024
• Amelin 2022
• American Institute of Aeronautics and Astronautics 1992
• Amico et al 2024
• Amin Boukenkoul et al 2017
• Amzajerdian et al 2013
• An et al 2025
• Analysis for Calculating the Lift-to-Drag Ratio for Flying Plates Having Square or Circular Shapes 1983
• Anderson 1960
• Anderson 1970
• Anderson 1975
• Anderson 1985
• Anderson and Holmes 1966
• Anderson and Schmidt 1986
• Anderson and Schmidt 1987
• Anderson and Sutera 1965
• Anderson et al 1959
• Anderson et al 1963
• Anderson et al 1967
• Anderson et al 1973
• Anderson et al 2015
• Anderson et al 2024
• Andino et al
• Ando and Ichikawa 1979
• Ando and Nishiwaki 1971
• Andrew and Cahn 1967
• Andrews 1970
• Andrews 1977
• Andrews 1998
• André Luiz Tenório Rezende et al 2026
• Anggoro 2021
• Anglin 1962
• Anoshin et al 2012
• Antonakis 2025
• Antonakis 2025
• Aoki and Ishigami 2022
• Appa and Ausman 1997
• Appa et al 1998
• Approach to solving the problem of landing an unmanned aerial vehicle on a moving landing platform 2025
• Approximate Method of Predicting Heating on the Windward Side of Space Shuttle Orbiter and Comparisons with Flight Data 1983
• Aprovitola et al 2021
• Aprovitola et al 2022
• Aradag et al 2007
• Arenson et al 1955
• Ariante et al 2022
• Arif and Sasongko 2021
• Armstrong 1977
• Arrington and Woods 1972
• Arık and Bilgiç 2022
• Asadullah et al 2018
• Ashford 1965
• Ashikhmina and Prosuntsov 2021
• Ashikhmina et al 2021
• Ashkenas 1965
• Ashkenas 1965
• Ashkenas 1984
• Ashkenas et al 1982
• Ashkenas et al 1983
• Atter 1982
• Audley and Hodge 1982
• August and McKinney 2005
• Aulakh 2017
• Aulehla and Besigk 1982
• Austin and William H. 1967
• Autenrieb 2025
• Automatic Landing 1964
• Awbi and Tan 1981
• Axelson and Hill 1981
• Aydın et al 2025
• Ayele et al 2024
• Aziz et al 2016
• Aziz et al 2020
• Aziz et al 2022
• Bach 1982
• Bader et al 2021
• Baek and Lee 2019
• Bagal 2026
• Bagherzadeh and Sabzehparvar 2015
• Bagrov 2018
• Bagrov 2019
• Baigang 2024
• Bailes et al 1975
• Bailey and Brownson 1979
• Bailey and Smith 1982
• Bailey et al 2025
• Bakulin et al 2016
• Balakrishnan et al 1997
• Balatti et al 2021
• Balesdent et al 2023
• Balla and Vad 2022
• Balusamy et al 2024
• Ban et al 2018
• Bandyopadhyay 1989
• Bandyopadhyay and Gad-el-Hak 1994
• Banerjee 2019
• Banks and Fisher 2006
• Banks and Paulson 1985
• Bannink and Reyn 1968
• Bansal et al 2026
• Bao et al 2021
• Bao et al 2022
• Baraldi and Conte 2023
• Barfield 1968
• Barman and Erzberger 1976
• Baron and Efrat 1979
• Baron and Levison 1973
• Barret 1998
• Barret 1999
• Barrett-Gonzalez and Wolf 2021
• Barros et al 2016
• Barton and Culp 1985
• Barzegar et al 2025
• Bashkirov et al 2023
• Bass and Bertin 1970
• Bass et al 1982
• Batill 1982
• Batson et al 1992
• Bauer 1980
• Baughman and Longeauay 2015
• Baum 1956
• Baumgartner and Elvin 1995
• Bautista et al 2023
• Beals and Targoff 1953
• Beam 1991
• Becker 1964
• Behr et al 2001
• Belaidouni et al 2016
• Bell 1964
• Bell 1965
• Bell and Strock 1980
• Bellman 1959
• Ben-Gida et al 2020
• Benbassat 2005
• Benbassat and Abramson 2002
• Bendarkar et al 2022
• Benedikt 1953
• Bengtson et al 1975
• Bennett and Abel 1982
• Bennett et al 2015
• Benson 2006
• Bentley 2009
• Bentley 2009
• Bentley 2009
• Beppu et al 1966
• Berci 2025
• Berci 2026
• Berger et al 2021
• Berger et al 2022
• Berger et al 2022
• Bergman 1971
• Bergmann et al 2021
• Berkes 1992
• Berninger 1990
• Berry 1986
• Berry and Powers 1970
• Berry and Powers 1970, Handling qualities of the XB-70 a
• Berry et al 1997
• Berry et al 2001
• Bert 1981
• Bert 1989
• Betin 1991
• Beyond Buran
• Bian et al 2018
• Bidinotto et al 2021
• Bie et al 2021
• Bihrle and Bowman 1981
• Billings and Durlach 2008
• Billings and Durlach 2010
• Bird 1970
• Bird 1970
• Bird and McLarty 1970
• Bivens 1986
• Black 1983
• Black and Shadow 1967
• Blaha et al 1976
• Blair 1972
• Blanchard and Larman 1987
• Blanchard et al 1982
• Blanchard et al 2015
• Blazek and Carrier 1974
• Bleeg et al 1967
• Bleviss and Struble 1954
• Blick et al 1978
• Blish 1980
• Boeing Scientific Research Labs Seattle Wa 1963
• Bogdanovic et al 1965
• Bohn 1967
• Bojun et al 2019
• Bollino et al 2006
• Bolton and Collins 1975
• Bonavita et al 2026
• Bond and Swanson 1953
• Bonner and Pride 1976
• Borek and Pool 1994
• Boroughs 1985
• Borowczyk et al 2017
• Borshchova and O’Young 2017
• Bortolussi et al 1987
• Bosworth and Stachowiak 2005
• Botelho et al 2022
• Bottasso and Montinari 2015
• Bourisli and Hamadeh 2020
• Bourne and Kirsten 1983
• Bowling and Key 1976
• Boyden and McKinney 1968
• Boylan 1965
• Boylan and Potter 1966
• Brackston et al 2016
• Brackston et al 2018
• Brand 1981
• Brandenstein 1984
• Brandon and Morelli 2016
• Brasseur 1994
• Brauckmann 1986
• Brauckmann and Scallion 2004
• Brauser 1982
• Bray 1980
• Bray and Scott 1981
• Bray and Scott 1981
• Bray et al 1960
• Brazzel 1963
• Breuer et al 2022
• Breuhaus 1979
• Breul 1963
• Brevault et al 2020
• Brice and Sugano 1978
• Bridson and Hancock 1970
• Britcher and Alcorn 1991
• Britcher et al
• Britcher et al
• Brociek et al 2023
• Brockers et al 2011
• Broglio 1961
• Brogna and Hawks 1978
• Brombacher 1926
• Brombacher 1935
• Broussard and Stengel 1977
• Brown 1950
• Brown and Lee 1971
• Brown and Redwine 1948
• Brown et al
• Brukarczyk et al 2021
• Brune and Dusto 1972
• Brunner et al 1966
• Bryson et al 1968
• Bryson et al 1969
• Buchnev and Danilov 2026
• Buck and Blanchard 1986
• Buckley and Marks 1978
• Buffo 1990
• Bugg and Sleeman 1967
• Bukanov and Zherekhov 2016
• Bulathsinghala et al 2017
• Bulathsinghala et al 2018
• Bull 1976
• Bull and Bridges 1985
• Bunnell and Delany 1947
• Buran 2025
• Buran in the spotlight
• Burcham et al 1997
• Burchett
• Burchett 2003
• Burger 1986
• Burian et al 2013
• Burken et al 2006
• Burkhart 1977
• Burris and Bender 1969
• Burris and Bender 1969
• Burton 1981
• Bushnell 1992
• Buteau et al 1980
• Butler et al 1966
• Bykerk et al 2020
• Bykerk et al 2020
• Béjar-Romero et al 2016
• Cacciola and Calabria 2026
• Cai et al 2026
• Calarese 1979
• Calarese 1980
• Calarese 1987
• Calarese and Walterick 1979
• Calhoun 2000
• Callaghan and Kunz 2021
• Camacho-Sánchez et al 2026
• Cameron 1974
• Campbell 1976
• Campbell et al 1996
• Campbell et al 1996
• Campbell et al 1997
• Campbell et al 2004
• Campbell et al 2022
• Campos and Marques 2021
• Cao and Tafti 2018
• Cao et al 2022
• Caplin
• Capone et al 1999
• Carden and McGehee 1983
• Carico 1998
• Carlson 1958
• Carlson and Reubush 1996
• Carr and Lagimoniere 2013
• Carradori et al 2026
• Carter and Brown 1974
• Carter and Kaul 1975
• Carter and Nagy 1996
• Carter and Sims 1981
• Carter et al 1997
• Cassanto 1969
• Cassanto 1971
• Castaldi et al 2023
• Castrichini et al 2018
• Catak et al 2024
• Cavalleri and Posey 1988
• Cavallo et al 1990
• Cea and Palacios 2023
• Cerimele et al 2017
• Chai et al 2020
• Chaloff et al 1974
• Chamberlin 1972
• Chamberlin and Blaha 1973
• Chandra 2020
• Chang 1982
• Chang and Muirhead 1987
• Chang et al 2026
• Chang et al 2026
• Chao et al 2010
• Chapman 1951
• Chapman and Perkins 1951
• Chartres et al 2005
• Chase 1971
• Chase 1979
• Chaudhary 2021
• Chaudhary et al 2001
• Che et al 2021
• Che et al 2023
• Cheatham 1959
• Cheatham and Hackler 1966
• Chekanov 2025
• Chen 2018
• Chen and Chen 2026
• Chen et al 2016
• Chen et al 2019
• Chen et al 2022
• Chen et al 2025
• Chen et al 2025
• Chen et al 2026
• Chen et al 2026
• Chen Yong et al 2015
• Cheng and Lai 2025
• Cheng et al 2021
• Cheng et al 2021
• Cheng et al 2022
• Chernenko and Burnashev 2022
• Cherry and De Wolf 1970
• Chevalier 1973
• Chima and Gerhart 1982
• Chin 1970
• Ching and Eaton 2019
• Chitrakaran et al 2005
• Choi et al 2015
• Choo et al 2018
• Chopra and Mittal 2021
• Chow 1959
• Chowhan 2016
• Chowhan et al 2019
• Chu et al 2024
• Chu et al 2026
• Cianciolo et al 2020
• Cicala and Miele 1956
• Clapp 1965
• Clark and Walters 1986
• Clark et al 1963
• Clarke 1958
• Cliff and Lutze 1972
• Coakley
• Cobar and Montalvo 2021
• Cochrane and Graham 1971
• Cohan and Hirsh 1966
• Cole and Malmuth 1989
• Coleman and Davis 2004
• Collins and Black 1969
• Collins et al 1970
• Colvin 2021
• Colwell 1966
• Colwell 1976
• Component Analysis and Synthesis for Fully Separated Flows with Special Consideration of Base Drag Reduction by Combusti 1976
• Compton 1996
• Compton et al 1981
• Computer vision-based approach for 2025
• Concorde Automatic Flight Control System 1971
• Condit et al 1966
• Condoleo and Theil 2018
• Conference on Aircraft Aerodynamics 1966
• Cong et al 2023
• Conner et al 1965
• Connolly 1965
• Connor and Wierwille 1983
• Conway 1960
• Cook 1995
• Coombe 1970
• Coombes et al 2017
• Cooper et al 2005
• Corban et al 2001
• Corda 1995
• Corda et al 1994
• Corsiglia et al 1981
• Costa et al 2000
• Cotton 1974
• Couch and Morris 1968
• Coue 2003
• Cox and Geymayer 1970
• Craft and Brazzel 1970
• Craig and Heffley 1973
• Crane et al 1974
• Crawford and Duiven 1973
• Crawford and Duiven 1973
• Crawford and Duiven 1974
• Crist and Symes 1981
• Crogan 1961
• Crombie and Moorhouse 1980
• Crosthwait 1970
• Crowell and Crowe 1973
• Cruikshank et al 2025
• Crumrine 1976
• Cruz and Ware 1992
• Cruz and Ware 1995
• Cruz et al 1989
• Cui et al 2015
• Cui et al 2023
• Cui et al 2023
• Cunningham 1971
• Curtiss 1971
• D and Singh 2016
• Da Ronch et al 2019
• Daforno 1982
• Dai et al 2021
• Daidzic 2016
• Dakka and Johnson 2019
• Dali and Jaramaz 2019
• Damljanović et al 2021
• Dana and Gentry 1970
• Dana et al 1969
• Darden 1985
• Darmawan et al 2025
• Das et al 2018
• Dau et al 1965
• Daughaday and Duwaldt 1955
• Daughetee 1974
• Davenport 1972
• Davenport 1974
• Davidson et al 1972
• Davis 1968
• Dawson and John G. 1962
• Day 2004
• de Alvear Cárdenas and Looye 2021
• De Angelis and Tang 1969
• de Bruin and Jones 2016
• De Martin et al 2022
• De Oliveira and Lavagna 2023
• De Oliveira and Lavagna 2024
• de Ridder and Mooij 2009
• De Ridder and Mooij 2011
• de Souza et al 2019
• De Stefano et al 2016
• De Troyer et al 2022
• de Visser and Pool 2023
• Dean and Mena 1983
• Decker 1992
• Decker 2002
• Decker et al 1993
• Deckert and Holzhauser 1973
• Deere and Hunter 1999
• Deere et al 2017
• Deese and Agarwal 1990
• Degani 2022
• Degani 2026
• Deiwert 1981
• Del Pizzo et al 2018
• Delebarre 2019
• Delgado and Arcioni 2000
• Delgado et al 2000
• Delgado et al 2001
• Dempster and Arnold 1969
• Dempster and Bell 1965
• Dempster and Roger 1967
• Deng 2026
• Deng and Duan 2016
• Deng and Zhao 2026
• Deng et al 2017
• Deniz et al 2025
• Dennis P. Dykstra 1980
• Dennis Quadros et al 2023
• Deshmukh and Majumdar 2025
• Desikan and Srinivasan 2018
• DeSpirito 2005
• Devanath and Beebi 2016
• Deveaux 1965
• Development of a correction algorithm for the integrated navigation system of an unmanned aerial vehicle in the landing task on a moving platform 2024
• DeVore et al 2022
• DeVoria and Mohseni 2017
• DeWispelare and Stager 1983
• Deyoung 1980
• Dhayalan et al 2018
• Di Camillo and Fisher 1959
• Dias 2023
• Dietenberger 1983
• Dieudonne et al 1976
• Difranco 1970
• DiFranco 1971
• Digges 1971
• Dike and Dunn 1958
• Ding and Huang 2025
• Ding et al 1988
• Ding et al 2020
• Dinul et al 2025
• Direct numerical simulations of hypersonic boundary layer transition over a hypersonic transition research vehicle model 2023
• Dirs 1966
• Di̇nç 2021
• Dodbele and Plotkin 1987
• Doetsch 1975
• Doko and Sasongko 2026
• Dollyhigh 1978
• Doman 2004
• Donahue 1997
• Donaldson 1955
• Dong and Cai 2017
• Dong et al 2021
• Dong et al 2022
• Dong et al 2023
• Dong et al 2025
• Donnelly et al 2006
• Dooley 1977
• Dorr et al 1992
• Dorr et al 1994
• Dougherty 1975
• Dougherty and Johnson 1993
• Dougherty and Lee 2016
• Douglas Aircraft Co Long Beach Ca 1962
• Douglas Aircraft Co Long Beach Ca 1963
• Dragos 1985
• Dragoş 1987
• Dragoş 1990
• Draper and Buck 1968
• Drela 1990
• Dress 1989
• Drinkwater and Cooper 1958
• Drinkwater and Vomaske 1966
• Du 2024
• Duan et al 2024
• Ducard and Carughi 2024
• Duke and Jones 1984
• Dunham et al 1971
• Durand and Wasicko 1967
• Durgesh et al 2004
• Durmus 2021
• Durmuşoğlu 2026
• Durmuşoğlu and Yıldırım 2025
• Dussart et al 2019
• Dussy et al 2011
• Dutasatria and Darma 2020
• Dutheil et al 2016
• Dutta et al
• Dutta et al 2022
• Dutton 1993
• Dutton 1993
• Dutton 1994
• Dzhandzhgava et al 2019
• e-CRV - Design study of a European Crew Return Vehicle 2004
• Earl 1967
• Ebrahimi et al 2024
• Eckhart 1972
• Edenborough 1968
• Edge and Perkins 1995
• Edwards 1950
• Edwards 1950
• Edwards 1950
• Edwards 1983
• Edwards and Foster 1973
• Edwards et al 1975
• Edwards et al 1997
• Effect of Ground Proximity on Aerodynamic Forces and Moments of Reusable Launch Vehicle at Subsonic Speed 2016
• Effect of Variations in weight or Normal Acceleration on the Ceiling of Jet-Propelled Aircraft, Correspondence 1955
• EFFECT OF VARIOUS AERODYNAMIC DRAG REDUCTION METHODS ON VEHICLE- A REVIEW 2017
• Efremov and Prodanik 2025
• Efremov et al 2020
• Efremov et al 2022
• Eggers et al 1957
• Eghlima and Mansour 2017
• Ehlers 1961
• Ehrenstein 2019
• Eichler 1970
• Elangovan et al 2021
• Eldredge et al 1965
• Elias 1974
• Eliseev et al 2014
• Elkins and Hatfield 1970
• Ellerbroek et al 2016
• Ellinwood 1967
• Elliott 1968
• Ellis 1976
• Elvin 1996
• Ema 1992
• Energiya-Buran 2007
• Eney 1968
• Engel and Putnam 2025
• Englar 1975
• Engle and Truly 1977
• Enmi et al 2018
• Ennix-Sandhu 2006
• EPilots is an algorithm that forecasts hard landing 2023
• Eraslan 2025
• Ercan et al 2024
• Eren et al 2015
• Erwin 1990
• Esabat et al 2025
• Eshelby 1982
• European Space Agency launches mini-spaceplane 2015
• Evangelisti and Pfifer 2024
• Evans 1954
• Ewell 1982
• Extension of a portable tactical instrument approach and landing system 1972
• Fairey Hydraulics Crashworthy Landing Gear for the Westland W30-300 Helicopter 1986
• Fairuz Izzuddin Romli et al 2023
• Falarski and Mort 1969
• Falarski and Mort 1970
• Falcão Arantes Filho and de Andrade 2016
• Fallon et al 1999
• Famellos et al 2024
• Fan and Cadot 2023
• Fan and Huang 2021
• Fan et al 2024
• Fang 2025
• Fang et al 2018
• Fang et al 2019
• Fang et al 2026
• Fasanella et al 2000
• Faulders et al 1968
• Favaro et al 2025
• Fawcett 1964
• Fearnside 1959
• Federici et al 2026
• Feigenbaum 1945
• Feinreich and Gevaert 1980
• Feinreich et al 1977
• Fellah and Guiatni 2019
• Feng et al 2015
• Feng et al 2025
• Fenwick 1966
• Fenwick 1967
• Ferguson et al 1963
• Ferrell et al 1974
• Ferrier et al 2016
• Feustel-Büechl 1988
• Fevralskikh 2021
• Fiddes et al 1985
• Figliola 2004
• Figliola 2005
• Filyashkin and Sidorenko 2020
• Finch and Matranga 1959
• Fink 1966
• Fink and Lastinger 1961
• First Glide Flight of Heavy Lifting Body Planned Soon 1966
• Fisher 1999
• Fisher 2007
• Fisher and Lanser 1994
• Fisher and Parcel 2007
• Fisher et al 2002
• Fletcher 1962
• Flight deck environment and 1973
• Flight Test Data Analysis of Hybrid Vertical Take-off and Landing Unmanned Aerial Vehicle 2016
• Flight Test Programme 1970, Flight Test Programme
• Flight Test Results Pertaining 1970, Flight Test Results Pertaining to
• Flight Testing 1992
• Flight Trials and Testing 1965
• Flight-test evaluation of engine power effects on lift and drag 1985
• Flying Controls and Automatic Landing 1963
• Fokin 1998
• Fong et al 1970
• Fonseca and Dilão 2018
• Ford 1989
• Forkun et al 2020
• Fosdick 1970
• Foss et al 1958
• Foster 1952
• Fournier and Sleeman 1974
• Fraenkel 1958
• Franklin and Innis 1972
• Franklin and Innis 1977
• Franklin and Innis 1978
• Franklin and Koenig 1973
• Franklin and Stortz 1993
• Franklin et al 1976
• Franklin et al 1980
• Franklin et al 1982
• Franklin et al 1986
• Fransson and Talamelli 2011
• Freed 1963
• Freeman 1980
• Freeman 1992
• Freeman and Spencer 1980
• Freer 1952
• Frink 1982
• Frisby 1960
• Frost and Dill 1986
• Frost and Rutherford 1963
• Fuhrmann 2003
• Fullerton 1975
• Furey 1980
• Furfaro et al 2020
• Gabrys et al 2019
• Gafka and Daugherty 2000
• Gai and Patil 1980
• Gai and Sharma 1981
• Gaifullin 2023
• Galanis et al 1998
• Gallagher 1971
• Gallagher et al 1972
• Gallaher et al 1996
• Gallay and Laurendeau 2016
• Gamse and Mort 1966
• Gan et al 2021
• Gannett 1964
• Gannett and McLean 1964
• Gao 2023
• Gao et al 2015
• Gao et al 2018
• Gao et al 2022
• Gao et al 2025
• Gao et al 2026
• García-Baena et al 2021
• Gardinier and Taylor 1999
• Gardner and Weir 1966
• Garg and Schmidt 1988
• Garkushenko and Vinogradov 2016
• Garodz 1975
• Garrett et al 1977
• Gartner and Baldwin 1973
• Gas Generators for Base Drag Reduction Fumers 1976
• Gatti and Quadrio 2016
• Gatto 1983
• Gatto and Babinsky 2018
• Gautam et al 2017
• Gautam et al 2018
• Gawehn et al 2011
• Geiger 1962
• General Electric Co Cincinnati Oh 1964
• Gentry 1972
• Gentry et al 1966
• George et al 1967
• George et al 1969
• George et al 2022
• Gerdes and Hynes 1971
• Gerken 1979
• Gersten 1963
• Gevaert and Feinreich 1977
• Ghee and Taylor 2000
• Gholap et al 2021
• Ghosh 1970
• Gibney 2015
• Gibson and Goetz 1971
• Gibson et al 1989
• Giguere et al 1997
• Gildersleeve and Amitay 2020
• Gillespie 1960
• Gillis and Mitchell 1957
• Gilyard 1972
• Gilyard 1999
• Gladkov and Panteleev 1988
• Gladkov I. A. Application of trajectory analysis to design a system of safe take-off and landing of aircraft 2017
• Gliding and Unpowered Flights 1995
• Gloss and Sewall 1983
• Godwin et al 1964
• Gogish and Pokrovskii 1978
• Goka 1975
• Goland et al 1964
• Goldberg 1966
• Gong et al 2020
• Gong et al 2022
• Goodall 1977
• Goodyer and Kilgore 1973
• Gopalarothnam and McGowan 2008
• Gorn 2003
• Grabe et al 2023
• Graham and Luskin 1946
• Graham et al 1954
• Grahame 1969
• Grant et al 2015
• Grantham 1989
• Grantham 2003
• Grantham and Williams 1987
• Grantham et al 1972
• Grantham et al 1985
• Grauer 2018
• Grauer 2020
• Grauer 2021
• Grauer 2021
• Grauer and Morelli 2025
• Greene 1977
• Greene 1988
• Greene 1989
• Gregory et al 2011
• Grewal et al 1976
• Griffin and Bellaire 1968
• Griffith and Crosby 1970
• Grigoli 2024
• Grodzovskii 1968
• Groomes 1964
• Guadagnini et al 2023
• Guan et al 2018
• Gunn-Golkin et al 2010
• Guo et al 2023
• Guo et al 2024
• Guo et al 2026
• Guttag and Reis 2017
• Guy 1976
• Gérard and Tumino 2006
• Haber 1952
• Haffner et al 2020
• Haffner et al 2022
• Haftka 1977
• Haftmann et al 1988
• Hagopian 2002
• Hague 1981
• Haines 1968
• Haise 1977
• Halbe et al 2014
• Hall and Boothe 1972
• Hall and Sandahl 1950
• Hall and Shtessel 2005
• Halyo 1977
• Halyo 1979
• Halyo 1983
• Halyo and Hueschen 1981
• Hameed and Bindu 2019
• Hameed and Bindu 2022
• Hameed et al 2024
• Hamilton et al 1980
• Han and Jiang 2018
• Han et al 2019
• Han et al 2024
• Han et al 2026
• Hancock 1960
• Hancock 1972
• Hankey 1963
• Hanson 2000
• Hantrais-Gervois and Destarac 2015
• Happy Landing 1990
• Hardy 1972
• Harmon 1974
• Harper and Cooper 1986
• Harper and Robert P. 1955
• Harper and Sardanowsky 1969
• Harry and Trobaugh 1966
• Hart 1974
• Hart 1987
• Harting 1981
• Hartley et al 1965
• Hasan 2024
• Hasen et al 2020
• Hashii and Thompson 2018
• Hassell 1960
• Hassell and Judd 1972
• Hastings 1956
• Haubelt et al 2001
• Hauptman 1987
• Hawthorne 1976
• Hawthorne 1976
• Hawthorne 1976
• He 2018
• He et al 2026
• Healey 1974
• Heath et al 1977
• Hebbar and Pashilkar 2016
• Hebbar and Pashilkar 2017
• Hedrick and Nichols 1975
• Heersink et al 2022
• Heffley 1974
• Heffley 1976
• Heffley and Jewell 1972
• Heffley and Schulman 1981
• Heffley et al 1982
• Helliwell 1952
• Heltsley and Crosswy 1983
• Henderson 1966
• Henning 1959
• Henriquez Huecas et al 2022
• Heo et al 2026
• Her et al 2016
• Hermes Spaceplane in MBB Wind Tunnel 1988
• Herrington et al 2023
• Hess 1972
• Hess 1984
• Hess 2016
• Hess 2019
• Hess and Chan 1988
• Hess and James 1975
• Hess and Mnich 1986
• Hess and Yousefpor 1992
• Hiba et al 2021
• Hicks and Huckabine 1989
• Hill and Ladson 1971
• Hiller Aircraft Corp Palo Alto Ca 1965
• Hillje and Tymms 1978
• Hinchey and Sullivan 1982
• Hindson et al 1982
• Hinshaw et al 1964
• Hirsch and McCORMICK 1966
• Hirsh 1965
• Hirst et al 2015
• HL-20 Personnel Launch System 1990
• HlCKEY 1969
• Hoare 1968
• Hodge et al 1981
• Hodgkinson et al 1976
• Hoerner 1950
• Hoffman et al 1970
• Hoffmann et al 2015
• Hofmann 1969
• Hofmann 1970
• Hofmann et al 1978
• Hoh and Mitchell 1983
• Holleman and Powers 1972
• Hollis and Hollingsworth 2012
• Holmes 1970
• Holmes et al 2016
• Holt et al 2015
• Holt et al 2016
• Homan et al 1980
• Hong 1999
• Hook and Freeman 1989
• Hooks and McMurry 1983
• Hopkins 1951
• Hopkins 1977
• Hornbuckle 2015
• Horneman and Kluever 2004
• Horta et al 1999
• Hortsen et al 1983
• Horvath et al 1990
• Horvath et al 2000
• Hossen and Saeedi 2026
• Howard 1974
• Howard and Goodman 1987
• Howell and Braslow 1955
• Howell et al 1990
• Howell et al 2003
• Hrishikeshavan et al 2015
• Hryshchenko et al 2017
• Hryshchenko et al 2025
• Hsin 1974
• Hsu et al 1990
• Hsu et al 2024
• Hu et al 2022
• Hu et al 2022
• Hu Meng-Quan and Zhang Mei-Zhong
• Huang 1968
• Huang 2019
• Huang and Chang 2025
• Huang and Miele 1967
• Huang and Wei 2025
• Huang and Yao 2019
• Huang and Zhang 2026
• Huang et al 2015
• Huang et al 2024
• Huang et al 2025
• Huang et al 2026
• Hubbartt and Strahle 1981
• Huerta 1969
• Hueschen 1984
• Huffman and McKinney 1971
• Hughes and McDonald 1965
• Hugo and Lago 2022
• Hui and Chen 2023
• Humphreys et al 1988
• Humphreys-Jennings et al 2020
• Hunter et al 1986
• Huntoon et al 1979
• Hwang et al 2026
• Hydraulics and landing gear 1971
• Hynes and Scott 1976
• Hynes et al 1988
• Ignatyev et al 2019
• Igreja and Lemos 2022
• Iizuka 2024
• Ikawa 1977
• Ilango and Ramanathan 2020
• Iliff 1977
• Iliff and Maine 1983
• Innis and Quigley 1961
• INVESTIGATION OF MODIFIED PROFILE OF HEAVY COMMERCIAL VEHICLE TO PRUNE AERODYNAMIC DRAG 2015
• Ioannis and Ioannis 2026
• Irvine 1968
• Irwanto and Artono 2018
• Iseri and Kameda 2021
• Iseri et al 2021
• Isogaya et al 2019
• Ito and Sakai 2021
• Ivler et al 2022
• Jackson 1955
• Jackson and Cruz 1992
• Jackson and Rivers 1998
• Jackson et al 1991
• Jackson et al 1991
• Jackson et al 1992
• Jackson et al 1993
• Jackson et al 1993
• Jackson et al 1994
• Jacobs 1973
• Jaffar et al 2020
• Jain 1988
• Jaquet and Riley 1964
• Jardin and Colonius 2018
• Jardin and David 2017
• Jayan et al 2024
• Jayaraman et al 2022
• Jebáček and Horák 2016
• Jenkins 1986
• Jenkins 2008
• Jenkins et al 1968
• Jeon et al 2022
• Jeong et al 2007
• Jeong et al 2009
• Jernell 1971
• Ji et al 2017
• Ji et al 2022
• Ji et al 2026
• Jia et al 2020
• Jia et al 2021
• Jiang and Ordonez 2008
• Jiang and Ordóñez 2009
• Jiang and Yang 2014
• Jiang et al 2019
• Jiang et al 2024
• Jiang et al 2026
• Jianghao et al 2017
• Jing et al 2020
• Joarder 2018
• Jobe 1984
• Jobmann and Thielecke 2024
• Johnson and Craig 1976
• Johnson and Dimarco 1972
• Johnson and Phatak 1990
• Johnson and Weir 1969
• Johnson et al 1980
• Johnson et al 1982
• Johnson et al 2018
• Johnson et al 2018
• Johnson et al 2020
• Johnston et al 1965
• Johnston et al 1965
• Jones 1976
• Jones and Crawford 1974
• Josefsson et al 2024
• Joyner 1969
• Joyner 1970
• Ju et al 2022
• Juang and Yu 2015
• Judd 1969
• Judge and Cummings 1966
• Jump and Padfield 2005
• Jump and Padfield 2006
• Junaid R and Beebi M 2015
• Jung 2024
• Jung and Bang 2015
• Jung et al 2025
• Jung et al 2025
• Jusko and Berger 2026
• Justh 2022
• Justiz and Patel 1988
• Kaden and Luckner 2022
• Kafer 1982
• Kai 2024
• Kaminsky and Johnson 1964
• Kaneko et al 2025
• Kang et al 2025
• Kannan et al
• Kannan et al
• Kansas Univ Lawrence 1952
• Kanwar 2024
• Kaplan 2002
• Kapote 2024
• Karakulov and Mitiukov 2026
• Kariya et al 2019
• Kariya et al 2020
• Karlgaard and “O’Farrell 2022
• Karlgaard et al 2019
• Karmali et al 1984
• Karn et al 2021
• Karr et al 1986
• Kase et al 2020
• Katoh et al 1989
• Katz 1989
• Katz and Roglin 2000
• Katz et al 1982
• Kawamura and Azimov 2022
• Kawamura et al
• Kawamura et al
• Kawasoe et al 2015
• Kawato et al 2002
• Kawato et al 2003
• Kawato et al 2005
• Kayser et al 1983
• Kazemipour and Zhang 2025
• Ke and Feng 2015
• Keene 1970
• Keener and Brownson 1972
• Kehoe 1987
• Kehoe 1988
• Kellaway 1972
• Keller and Rudnik 2015
• Kelley et al 1982
• Kempel 1971
• Kempel and Manke 1974
• Kempel and Painter 1993
• Kempel and Thompson 1971
• Kempel et al 1970
• Kempel et al 1971
• Kempel et al 1975
• Kempel et al 1994
• Kentfield et al 2006
• Kenyon 1961
• Keribayeva et al 2022
• Keskar and Slater 1979
• Keskin 2026
• Kettle 1958
• Key 1982
• khosravi et al 2015
• Khot et al 2025
• Khurana and Suzuki 2013
• Khurana et al 2012
• Khurana et al 2018
• Kida and Miyai 1978
• Kidd 1966
• Kidd and Bull 1963
• Kiefer et al 2016
• Kiehn 2020
• Kieszek et al 2024
• Kilgore and Davenport 1974
• Kilgore and Davenport 1975
• Kilgore and Dress 1984
• Kilgore et al 1974
• Kim and Costello 2016
• Kim and Kim 2026
• Kim and Tahk 2019
• Kim et al 2017
• Kim et al 2019
• Kim et al 2020
• Kim et al 2021
• Kim et al 2021
• Kim et al 2021
• Kim et al 2023
• Kim et al 2025
• Kim et al 2026
• King et al 1999
• Kistyarev and Wang 2025
• Klein et al 1983
• Kleinman and Baron 1973
• Kless et al 2012
• Klochan et al 2017
• Kluever 2004
• Kluever 2007
• Kluever 2007
• Kluever 2022
• Kluever and Horneman 2005
• Kluever and Neal 2015
• Kluever et al 2009
• Knapp and Barton 1968
• Knaus 1983
• Kneeling landing gear 1973
• Knight and Naiman 2009
• Knight and Tso 2005
• Knowles 2016
• Ko and Schuster 1983
• Ko and Schuster 1984
• Kobayashi and Maita 1995
• Kocamer et al 2022
• Kock and Fulton 1970
• Kock and Painter 1968
• Kock and Painter 1969
• Kock et al 1972
• Koenig and Brady 1960
• Kohama and Yoon
• Kohlman 1979
• Koklu et al
• Kolesar 1971
• Kolesar et al 1970
• Kolesar et al 1970
• Kolesnikov 1967
• Komerath et al 1998
• Komov 2022
• Kong et al 2025
• Kongkaew et al 2022
• Konstantinidis and Förstner 2020
• Koo et al 2015
• Kordes and McKay 1962
• Kordos et al 2023
• Korkischko and Konrath 2017
• Korsun and Moung Htang 2023
• Korsun et al 2017
• Korsun et al 2018
• Korsun et al 2024
• Korzun and Chambers
• Korzun et al
• Korzun et al 2020
• Kotfila and Painter 1969
• Kothari 2021
• Kotitschke et al 2026
• Kozhanov et al 2022
• Kozina 1976
• Kraft et al 1971
• Kraiko and Shelomovskii 1984
• Kraiss and Baty 1978
• Kramer et al
• Kramer et al 2012
• Kramer et al 2013
• Krammer et al 2022
• Kranz 1954
• Krawczyk et al 2019
• Krebs et al 1977
• Krek and Stalker 1992
• Krevor et al 2011
• Krevor et al 2011
• KrishnaKumar et al 1995
• Krishnan and Roy 2022
• Krishnan and Sajikumar 2023
• Kuchinka 1966
• Kuchta and Friedman 1972
• Kuessner 1954
• Kuhlman and Liaw 1987
• Kuhn 1959
• Kuhn 1981
• Kulakowski and Haskell 1961
• Kulumani and Lee 2022
• Kumar and Ghosh 2023
• Kumar and Mahulikar 2017
• Kumar and Padhi 2024
• Kumar et al 2018
• Kumar et al 2025
• Kumar S et al 2022
• Kuptsov and Ostroukhova 1977
• Kurdel et al 2024
• Kurita et al 2006
• Kurkowski et al 1976
• Kuttieri and Sinha 2023
• Kwon 2017
• Labbe et al 1999
• Lagimoniere and Avram 2024
• Laili and Widayaka 2024
• Laine 1982
• Laitone 1978
• Laitone 1978
• Laitone 1989
• Lamar et al 1981
• Lambregts and Creedon 1980
• Lampropoulos and Sarris 2025
• Lampropoulos et al 2025
• Lampton et al 2024
• Lan 1984
• Lan et al 2016
• Lan et al 2020
• Lan et al 2021
• Landing Area/Landing Gear Compatibility - A Brief History of SAE/Corps of Engineers Cooperation
• Landing gear 1973
• Landing gear 1974, Landing gear
• Landing gear 1974, Landing gear
• Landing Gear 1975
• Landing Gear 1986
• Landing Gear Alignment
• Landing Gear Ancillary Equipment 1968
• Landing Gear Stability
• Landing Gear System Development Plan
• Lang et al 2025
• Langston et al
• Lapygin and Tret’yakov 1986
• Lara et al 2022
• Larson 1972
• Latham and Sorensen 1973
• Lauchle 1974
• Launius 2013
• Lavrukhin and Talyzin 2017
• Law and Stegall 1984
• Lawrence 1951
• Lawrence 1953
• Lawrence et al 2018
• Layton 1970
• Layton and McTigue 1969
• Le Ngoc et al 2010
• Lebacqz and Forrest 1982
• Lee 1977
• Lee 1985
• Lee 1990
• Lee 2011
• Lee and Lee 2017
• Lee and Libbey 1961
• Lee and Mesbahi 2017
• Lee and Park 2021
• Lee and Park 2025
• Lee and Swegle 1963
• Lee et al 1973
• Lee et al 2007
• Lee et al 2017
• Lee et al 2021
• Lee et al 2025
• Lee et al 2026
• Leeman et al 2022
• Lehman 1964
• Lehman 1966
• Lehnert and Schermerhorn 1959
• Lei et al 2017
• Lei et al 2022
• Leite et al 2022
• Leland and Thompson 1975
• Leoni 1983
• Leparoux et al 2022
• Levi and Nelson 1964
• Levison 1982
• Levy 1969
• Leyds 1956
• Li 1960
• Li and Hu 2018
• Li and Zhou 2022
• Li et al 2010
• Li et al 2012
• Li et al 2015
• Li et al 2016
• Li et al 2017
• Li et al 2019
• Li et al 2021
• Li et al 2021
• Li et al 2022
• Li et al 2022
• Li et al 2022
• Li et al 2024
• Li et al 2024
• Li et al 2024
• Li et al 2024
• Li et al 2024
• Li et al 2025
• Li et al 2025
• Li et al 2026
• Lian 2011
• Liang 2024
• Liang et al 2014
• Liang et al 2016
• Liang et al 2022
• Liang et al 2024
• Liao and Chen 2016
• Liao et al 2023
• Liao et al 2023
• Liao et al 2026
• Lichota 2023
• Lichota et al 2017
• Liebeck 1978
• Liebeck and Ormsbee 1970
• Liechty et al 2002
• Lift/Drag Ratios of Optimised Slewed Wings at Supersonic Speeds 1962
• Lim et al 2020
• Lin 2025
• Lin and Ash 1986
• Lin et al 2021
• Lindquist 1952
• Ling 1970
• Liu 2019
• Liu and Liu 2022
• Liu and Shen 2015
• Liu and Stumpf 2018
• Liu and Tan 2024
• Liu and Wang 2024
• Liu and Yang 2024
• Liu and Zhao 2026
• Liu et al 2017
• Liu et al 2019
• Liu et al 2021
• Liu et al 2021
• Liu et al 2022
• Liu et al 2023
• Liu et al 2024
• Liu et al 2025
• Liu et al 2025
• Liu et al 2026
• Liu et al 2026
• Lloyd et al 1978
• Lobanovskii 1983
• Lobbia 2017
• Lock 1986
• Lockenour and Layton 1976
• Lockheed-Georgia Co Marietta 1969
• Lockman 1967
• Loddoni et al 2010
• Lofthouse and Cummings 2017
• Logan 1976
• Logan et al 1978
• Lokos et al 2015
• Lombaerts et al 2017
• Long et al 2022
• Loomis et al 2004
• Lopez-Morales et al 2026
• Lorenz 2015
• Lorenzetti et al 1969
• Lorite-Díez et al 2019
• Loth and Boyle 1969
• Loth et al 1976
• Lottati 1984
• Lotze et al 1977
• Lovell and Lipson 1949
• Lowrance and Smith 1996
• Lozino-Lozinskii and Neiland 1989
• Lu 1996
• Lu 1997
• Lu 2024
• Lu et al 2018
• Lu et al 2023
• Lucas 1978
• Lucero 1985
• Lucka and Michael 1999
• Luderer and Thielecke 2025
• Luers and Reeves 1975
• Lunar landing rehearsal 1969
• Lundry 1967
• Lundry 1977
• Lunghi et al 2015
• Lunghi et al 2022
• Lunghi et al 2024
• Lungu 2022
• Lungu and Lungu 2015
• Lungu and Lungu 2015
• Lungu and Lungu 2016
• Lungu and Lungu 2016
• Luo et al 2019
• Luo et al 2026
• Luong 2026
• Luong et al 2025
• Lusty and Miele 1966
• Lutze 1977
• Lux-Baumann and Burkes 2005
• Lystad 1975
• Lyu and Liem 2020
• Lyu et al 2018
• M2-F2 Lifting Body Accident Summary 1967
• Ma 1989
• Ma 1992
• Ma 2025
• Ma and Chen 2023
• Ma et al 2017
• Ma et al 2018
• Ma et al 2018
• Ma et al 2019
• Ma et al 2022
• Ma et al 2025
• Ma et al 2025
• Maass et al 2020
• Mabey and Welsh 1987
• MacConochie 2000
• Machin 2000
• Machin et al 1999
• Machin et al 2001
• MACKlNNON and Madden 1972
• MACKlNNON and Madden 1972
• Macmillan 1950
• Macwilkinson et al 1974
• Macwilkinson et al 1974
• Magee and Taylor 1971
• Magee and Taylor 1971
• Mageed Mahmoud et al 2016
• Mahajan 2024
• Mahmood et al 2023
• Maikapar 1966
• Maikapar 1993
• Maine and Iliff 1979
• Mair 1965
• Mair 1969
• Maita et al 1982
• Maiuzzo 1970
• Majendie 1963
• Makarenko et al 2017
• Makizono et al 2015
• Malcom 1969
• Mallery and Neebe 1966
• Mallet et al 1992
• Malpica and Lusardi 2013
• Mamo and Gopal 2023
• Mandal and Gu 2016
• Manke and Love 1975
• Manke et al 1970
• Mann and Carlson 1991
• Manshadi and Saghafi 2018
• Mao and Zhao 1990
• Mao et al 2021
• Mao et al 2023
• Marchman and Abtahi 1985
• Margason and Morgan 1975
• Mariotti et al 2015
• Mariotti et al 2017
• Mariotti et al 2019
• Mariotti et al 2024
• Markina et al 2020
• Marks and Buckley 1978
• Martin 1964
• Martin and Brazzel 1970
• Martina 1956
• Martindale and Carter 1975
• Marwege and Gülhan 2023
• Masaki and Yakura 1968
• Maskew 1977
• Mastrocola and Assadourian 1947
• Mathavaraj and Padhi 2020
• Mathavaraj et al 2010
• Mathematical model of the UAV landing approach system on the example of the course-glide path system 2023
• Matheny 1974
• Matranga 1961
• Matranga 1961
• Matranga and Armstrong 1959
• Matranga and Menard 1959
• Matsubara et al 2020
• Matt et al 2025
• Maull 1980
• Mayanna et al 2006
• Mayer and Hamer 1961
• Mazurov and Takovitskii 2022
• Mbikayi et al 2024
• McBrayer and Robinson 1965
• McComb and Tanner 1988
• McConnell et al 2024
• McCormick 1959
• McCormick 1969
• McCutchen 1989
• McDonald and Stevens 1970
• McDonnell Aircraft Corp St Louis Mo 1950
• McFadden and Bons
• McGee et al 1970
• McGee et al 1981
• McGee et al 1984
• McGehee 1985
• McGehee and Dreher 1982
• McGough et al 1974
• McIntyre 1963
• McKay and Noll 1967
• McKlNNEY and DOLLYHlGH 1971
• McPherson et al 1949
• McTigue 1970
• McTigue and Ryan 1968
• McVey et al 1969
• Meckler 1965
• Mehta et al 2016
• Mele 2022
• Memon et al 2021
• Meng et al 2025
• Mennell 1975
• Mennell 1976
• Menon et al 1989
• Menon et al 2022
• Menon et al 2025
• Menter et al 2022
• Merhav and Grunwald 1978
• Meriwether and Harris 1962
• Merlin 2006
• Merlin 2014
• Merrem et al 2020
• Merrick 1971
• Merrick et al 1990
• Merz 1979
• Merz et al 1985
• Messanelli et al 2019
• Messiter 1963
• Methodology for assessing the accuracy of UAV landing on the runway 2022
• Metodiev 2024
• Metzger and Hedrick 1975
• Meyerson 1990
• Meyerson 1998
• Meyn et al 1993
• Michael A. Bolender 2006
• Micol 1990
• Middleton and Bergeron 1974
• Miele 1955
• Miele 1957
• Miele 1968
• Miele and Damoulakis 1969
• Miele et al 1987
• Miele et al 1988
• Mihalik and Keane 2022
• Mikhail 1979
• Miles 1953
• Miles 1954
• Milla and Blick 1966
• Miller 1970
• Miller and Clark 1965
• Miller et al 1974
• Minami and Tsukamoto 2006
• Mineck 1995
• Mineck and Vijgen 1993
• Minott et al 1976
• Minzner 1967
• Minzner et al 1976
• Miotto and LePome 2003
• Mirels 1953
• Misra and Bai 2019
• Mitcham et al 1951
• Mitchell et al 2003
• Mitcheltree et al 1999
• Miyajima 1969
• Mo et al 2024
• Mobile Autonomous Recovery Landing Principle and Control Method for Unmanned Aerial Vehicle 2024
• Modal Analysis of a Typical Landing Gear Oleo Strut 2018
• Modali et al 2020
• Mohamed and Dongare 2018
• Mohammadkarimi and Nobahari 2018
• Mohrfeld-Halterman and Uddin 2016
• Mohrfeld-Halterman and Uddin 2016
• Moldovan et al 2024
• Moller and Elliott 1972
• Monaco et al 2001
• Monstein et al 2019
• Montella et al 2025
• Montella et al 2025
• Montella et al 2026
• Montez and Madden 1982
• Montgomery and Hatch 1969
• Mooij 2024
• Mooij and Hanninen 2009
• Mooij and van Gool 1978
• Moore et al 1980
• Moore et al 2008
• Moreira et al 2022
• Morel 1979
• Morelli and Cooper 2015
• Morikawa and Puckett 1951
• Morino 1973
• Morino and Kuo 1974
• Morio et al 2007
• Morio et al 2009
• Morio et al 2010
• Morris 1961
• Morris and McGehee 1983
• Morris et al 1993
• Morth 1972
• Morth 1973
• Morton 1956
• Moser 1961
• Mosiężny et al 2020
• Moszczynski et al 2026
• Mount 1965
• Moussie et al 2024
• Mu et al 2016
• Mu et al 2018
• Mu et al 2019
• Mu et al 2022
• Mu et al 2023
• Mu et al 2025
• Muchina 2020
• Muchmore 1988
• Mudd 1969
• Muehter 1974
• Mueller 1970
• Mueller 1982
• Mueller 1985
• Mueller and Torres 2001
• Muhammad et al 2025
• Mukundan et al 2022
• Mulder 1977
• Mull and Algranti 1960
• Muller 1967
• Muller and Gasko 1967
• Munday et al 2000
• Munoz-Burgos and McDonough
• Munoz-Burgos et al 2025
• Munoz-Burgos et al 2026
• Munusamy et al 2022
• Murphy 1992
• Murrell 1969
• Mustafa and Shofiqul 2016
• Myers et al 1982
• Myers et al 1986
• Myers et al 1987
• Myring 1976
• Nabae et al 2018
• Nabae et al 2025
• Nadkarni 1981
• Naeseth 1970
• Naftel and Powell 1993
• Naftel and Talay 1993
• Nag et al 2023
• Nagarajan and Jothiraj 2024
• Nagarani et al 2020
• Nagata et al 1973
• Nagel 1983
• Nagy and Kirsten 1976
• Nair and Kukreja 2025
• Naish 1980
• Naka and Hashimoto 2015
• Narayana and Selvaraj 2023
• Natarajan et al 2024
• Naughton 1999
• Navarro-Tapia et al 2017
• Nebylov and Tomita
• Nebylov et al 1999
• Nekkanti et al 2023
• Nekrasov et al 2025
• Nenni 1980
• Neuhaus 2018
• Newell et al 1963
• Newman 1982
• Newton and Kroo 2025
• Ngo and Sultan 2022
• Nguyen et al 2018
• Nguyen et al 2021
• Nguyen et al 2024
• Nguyen et al 2026
• Ni et al 2023
• Ni et al 2024
• Nichele et al 2025
• Nicholson 1973
• Nicholson and lowry 1966
• Nicolaides 1976
• Nicolás-Pérez et al 2017
• Nielsen 1985
• Niessen 1973
• Nieto et al 2024
• Nietubicz 1975
• Ning et al 2007
• Nissen and Gadeberg 1944
• Niu et al 2018
• Nixon 1975
• Nixon 2006
• Non-Contact Measuring Section in the Problem of Hypersonic Aerodynamics 2019
• Nonnenmacher and Jones 2016
• Nonweiler 1955
• Nonweiler 1955
• Nonweiler 1960
• Norman 1969
• Norton 1990
• Nowak et al 2022
• Nugent 1959
• Nugroho et al 2024
• Numerical Investigation of Impinging Planar Shock Wave Interaction with Axisymmetric Slender Body 2025
• Numerical Optimization on Approach and Landing for Reusable Launch Vehicle 2016
• Numerical Research on Effect of Base Bleed Type on ‎Operation Process of Base Bleed Projectile 2021
• Numerical study of aerodynamics drag and flow characteristics of the high-speed train head design 2024
• Numerical Study on the Drag Reduction for a D-Shaped Bluff Body with Wavy Trailing Edge Structures 2025
• Nutt and Martindale 1976
• Nutt et al 1979
• O’hara 1971
• Obeid et al 2019
• Obermark 2004
• Obryan et al 1979
• Office Of Research Analyses Holloman Afb Nm 1963
• Oglesby 1975
• Ogneru and Raileanu 2026
• Ogren et al 1974
• Oh and Choi 2018
• Ohta and Sugiura 1973
• Okamoto et al 2019
• Oktay et al 2018
• Okumoto and Elsanker 1973
• Ol 2007
• Olson 2015
• Orlando 2020
• Ormsbee and Chen 1972
• Ortloff 1968
• Osborne and Kelly 1960
• Osder 1970
• Osder and Keller 1971
• Osder et al 1976
• Ostapenko and Stradomskiy 2018
• Othman and Kanazaki 2016
• Otsu 2016
• Otsu 2018
• Ovcharenko and Poplavsky 2021
• P.V and Laxman 2023
• Padmanabhan and Dowell 2015
• Page and Anderson 1996
• Painter 1983
• Painter and Erickson 1984
• Painter and Sitterle 1972
• Painter and Sitterle 1974
• Palanivendhan et al 2021
• Paletta et al 2015
• Palmer and Petitt 1977
• Palmer et al 1994
• Palmer et al 1995
• Pan 2025
• Pan and Pi 2025
• Pan et al 2024
• Park 2020
• Park and Rokhsaz 2003
• Park et al 2019
• Park et al 2022
• Park et al 2024
• Parker and Goode 1976
• Parkinson 1983
• Parrish and Martin 1975
• Parrish and McKissick 1979
• Parrish et al 1976
• Parrish et al 1979
• Pasandideh Fard and Sahaf 2016
• Pasek and Shanahan 1954
• Pasha et al 1982
• Pate 1964
• Pate and Deitering 1963
• Patel and Guven 1976
• Patton 2004
• Paul et al 2019
• Paul et al 2022
• Pauli 1965
• Pavel 2022
• Pavia et al 2019
• Pavlov and Simakova 2021
• Payne 1968
• Payne 1980
• Payne et al 1980
• Pecora 2021
• Pedigree Aerodynamic Shape Design of High-Speed Trains 2023
• Peiró Frasquet et al 2023
• Peng et al 2022
• Peng et al 2025
• Penland 1975
• Penland and Romeo 1971
• Penland et al 1978
• Pepper 1969
• Pepper and Biesterveld 1973
• Perminov 1969
• Perrone 1983
• Perrone 1984
• Pesch 1980
• Pessanha Santos et al 2023
• Peters 1977
• Peters 1981
• Peterson 1981
• Peterson 2004
• Peterson and Sandlin 1981
• Peterson et al 1980
• Petrie 1968
• Petrishchev 2018
• Petrishchev 2018
• Petrov and Soudakov 2016
• Pezzella and Viviani 2016
• Pezzella and Viviani 2024
• Pezzella et al 2011
• Pfaff 1965
• Pfaff 1968
• Pfeifle et al 2022
• Pfenninger and Vemuru 1988
• Pham and Nguyen 2025
• Pham et al 2020
• Pham et al 2025
• Phan et al 2024
• Phillips et al 1973
• Piddington 1957
• Pidvysotskyi 2021
• Pierrottet et al 2014
• Pierson 1985
• Pierson and Chen 1979
• Pike 1977
• Pinebrook and Dalton 1983
• Pinebrook and Dalton 1983
• Pinn
• Pirooz and Fateh 2019
• Pirooz et al 2021
• Pisharoty 1959
• Pitkin 1968
• Pittsburgh Univ Washington Dc Research Staff 1966
• Platou 1974
• Platou 1975
• Platou and Nielsen 1976
• Podruzhin and Zagidulin 2017
• Podruzhin et al 2021
• Pogosyan and Vereikin 2020
• Polhamus 1953
• Polhamus 1968
• Polhamus 1984
• Polukhin and Ostapenko 2019
• Poritzky 1971
• Portapas and Cooke 2020
• Potter and Whitfield 1957
• Powell 1993
• Powell and Cruz 1991
• Powers 1980
• Powers 1982
• Powers 1984
• Powers 1984
• Powers 1986
• Powers 1986
• Powers 1988
• Powers 1988
• Powers and Sarrafian 1986
• Powers et al 1986
• Prabhu et al 2025
• Prasad 2022
• Predachenko and Lemko 2019
• Presz et al 1978
• Price 1978
• Price and Blanchard 1981
• Price and Earl A. 1981
• Pritchard 1969
• Probst et al 2017
• Proceedings of the Seventeenth 1981
• Prosvirin and Kharchenko 2016
• Pruin 1970
• Prévôt and Onken 1995
• Pu 2015
• Puchalski and Kowalick 1976
• Purcell et al 2025
• Putman 1974
• Pyle 1971
• Pyle and Ash 1970
• Pytka et al 2022
• Qi and Wang 2019
• Qi and Zhao 2025
• Qi et al 2021
• Qiu et al 2016
• Rabaa and Kuppusamy 2022
• Radhakrishnan et al 2023
• Ragsdale et al 1974
• Rahma and AlQadi 2025
• Raillon et al 1992
• Raju and Viswanath 1998
• Ramaswamy and Schreyer 2022
• Ramprasadh and Devanandh 2015
• Rampy 1966
• Rana et al 2017
• Rana et al 2017
• Raney and Lallman 1991
• Raney et al 1995
• Ranjan and Gaitonde 2020
• Rao 1980
• Rao 1983
• Rao et al 2023
• Rasky et al 2006
• Rasmussen 1978
• Rataczak et al 2024
• Rathore and Havaldar 2023
• Rauer 2019
• Raz et al 1989
• Reaser 1997
• Recasens et al 2005
• Redding 1984
• Rediess 1976
• Reed 2005
• Reed 2006
• Reed et al 1997
• Reeder 1958
• Reggiori 1971
• Rehman 2022
• Reimann 2016
• Reller and Seegmiller 1960
• Reschak 1971
• Reshotko 1979
• Response Analysis of Landing Leg Deployment and Landing Transient Impact of Reusable Launch Vehicle 2026
• Reubush 1975
• Reubush 1975, The effect of Reynolds number on
• Reubush 1976
• Reubush 1976, Effect of Reynolds number on the
• Reusable Launch Vehicle 1995
• Reusable Launch Vehicle Landing Gear Mechanism Technologies A Review 2026
• Revell 1971
• Rhoads 1967
• Ribner 1960
• Ricciardi et al 2019
• Richards and Tate 2023
• Richards et al 2001
• Richards et al 2015
• Riebe 1973
• Rigatos 2021
• Riggins and Camberos 2020
• Riley and Miller 1980
• Riley and Miller 1982
• Ringel and Levin 1985
• Rittenhouse 1959
• Rivers et al 1991
• Rizvi et al 2013
• Rizvi et al 2017
• RlDHA 1969
• Roberts 1963
• Robertson 2017
• Robinson 1978
• Robinson and High 1974
• Rockwell 2011
• Rodden 1984
• Rodi and Bennett 2012
• Rodriguez 1991
• Rodriguez et al
• Rodríguez de Cos and Acosta 2020
• Roger et al 1975
• Rogers 1973
• Rogers and Fasciano 2016
• Rogerson 1960
• Rohling 1969
• Roithmayr and Pei 2024
• Rokhsaz and Kliment 2017
• Rom and Bober 1974
• Romere and Whitnah 1983
• Romere et al 1978
• Romere et al 1979
• Romero 2021
• Roschke 1955
• Roshko 1993
• Ross 1980
• Ross et al 1995
• Rothman and Chernoff 1961
• Ruan et al 2024
• Rubin 1971
• Rudy 1984
• Ruf et al 1996
• Ruhland and Breitsamter 2023
• Ryu et al 2022
• Ryu et al 2025
• S. Hameed and G. R 2021
• Saccani 2020
• Sachs 1980
• Saderla et al 2017
• Saetti and Rogers 2024
• Sager 1995
• Sagliano 2018
• Sagliano 2019
• Sai Madhuri et al 2021
• Sai-fei et al 2016
• Said Khoudiri 2025
• Saint-Mard and Hendrick 1999
• Sakaki and Ueba 2025
• Salgueiro Filipe et al 2009
• Saltzman 1961
• Saltzman and Ayers 1981
• Saltzman and Ayers 1982
• Saltzman et al 1956
• Saltzman et al 1994
• Saltzman et al 1999
• Saltzman et al 2002
• Saltzman et al 2007
• Sanchez et al 2018
• Sanders 1957
• Sanders 1965
• Santho et al 2026
• Santos 2011
• Saprykin 2020
• Sarah et al 2025
• Sardou 1986
• Sarkar et al 2021
• Sarker et al 2024
• Sarrafian 1984
• Sarrafian 1984, Evaluation of HiMAT aircraft land
• Sarrafian and Powers 1988
• Sarwar et al 2025
• Sasaki et al 2025
• Sathish Kumar Sunnam et al. 2019
• Saunders et al 1991
• Savage and Tinling 1959
• Scallion 1999
• Schade and Crane 1965
• Schade et al 1954
• Schadow and Chieze 1978
• Schetz et al 1980
• Schetz et al 1981
• Schieni et al 2024
• Schiff and Sturek 1981
• Schmidt 1979
• Schmidt and Anderson 1985
• Schmidt and Breuer 2015
• Schmidt et al 2015
• Schmitt and Burchett 2004
• Schneider 2009
• Schnitzer 1958
• Scholz et al 2026
• Schoombie et al 2017
• Schouler et al 2021
• Schouler et al 2021
• Schuet et al 2017
• Schuler et al 1972
• Schultz and Zagalsky 1972
• Schumacher 1952
• Schwanz 1972
• Schwartz and Wray 1969
• Schwartzberg 1975
• Scorsoglio et al 2022
• Seager and Agarwal 2017
• Sebryakov et al 2019
• Seckel 1975
• Sederstrom et al 1973
• Sedlmair et al 2019
• Sedlmair et al 2022
• Sedney 1982
• Seegmiller 1968
• Seginer and Salomon 1986
• Seibel 1963
• Seitz and Goodson 1973
• Selby and Miandoab 1990
• Semaan and Nordhoff 2022
• Sen 1990
• Sen 1990
• Senthil Kumar and Shanmugam 2023
• Seraj and Martins 2025
• Serdarevic-Kadic et al 2024
• Setterfield et al 2021
• Shafer et al 1983
• Shafer et al 1984
• Shaffer et al 2005
• Shakti et al 2017
• Shao et al 2014
• Shaqarin et al 2021
• Sharenson 1966
• Shawyer 2023
• Sheila Tobing 2022
• Shen 1952
• Shen et al 2024
• Shepard et al 2023
• Sher Afghan Khan et al. 2018
• Shevell 1978
• Shevloff and Reid 1953
• Shi 2025
• Shi et al 1969
• Shi et al 2023
• Shigenori and Michiyo 1985
• Shimada and Ohwada 2020
• Shimizu et al 2019
• Shimizu et al 2019
• Shin et al 1999
• Shin et al 2001
• Shmyglevskii 1966
• Shomber and Gertsen 1967
• Shrewsbury 1968
• Shrivastava and Stengel 1989
• Shtessel and Krupp
• Shtessel et al 1997
• Shtessel et al 2000
• Shtessel et al 2003
• Sibert 1943
• Sickles and Lawrence 1991
• Siemers and Larson 1978
• Siemers and Larson 1979
• Sillen 1993
• Silva Cotta et al 2024
• Sim 1973
• Sim 1973
• Sim 1976
• Simmons 2023
• Simmons et al 2023
• Simmons et al 2023
• Simmons et al 2023
• Simos and Jenkinson 1985
• Simplício et al 2019
• Sims and Hahn 1964
• Sims and Schnitzer 1952
• Singh et al 2022
• Singh Singh and Kanti Ghosh 2023
• Single pilot IFR flight surve 1986
• Sirignano and MacArt 2023
• Sisalah et al 2015
• Siva Krishna Reddy et al 2021
• Sivakumar and Syedhaleem 2018
• Sivakumar et al 2021
• Sivan and Pandian 2018
• Sivaramakrishnan 1981
• Sivasubramanian et al 2006
• Skorupka 2024
• Slaughter 1958
• Slayton 1977
• Sleeman 1971
• Smeltzer et al 1975
• Smetana and Knepper 1973
• Smith
• Smith 1965
• Smith 1968
• Smith 1977
• Smith 1979
• Smith 1981
• Smith 1990
• Smith and Campbell 1996
• Smith and Edwards 1980
• Smith and Klettner 2022
• Smith et al 1970
• Smith et al 1973
• Smith et al 1974
• Smith et al 1990
• Smith et al 1998
• Smits 2007
• Smits 2009
• Snyder 1950
• Snyder and Zumwalt 1969
• Soard 1974
• Soard 1975
• Soistmann and Spain 1993
• Some Current Types of Landing Gear 1968
• Songhui et al 2020
• Soontornpasatch 2018
• Sostaric et al 2019
• Space Shuttle Aerothermodynamics Technology Conference. Volume 3 Aerodynamics 1971
• Space Shuttle Orbiter Approach 1977
• Space Shuttle Orbiter Approach 1978
• Space Shuttle Program Orbiter Approach and Landing Test 1977
• Space shuttle trajectory management, navigation, guidance, and control during approach and landing Interim report 1970
• SPACEPLANE HISTORY 2002
• SPACEPLANE LOW-COST POTENTIAL 2002
• Spady 1977
• Spady 1978
• Spain et al 1993
• Spalart and Garbaruk 2021
• Spearman 1984
• Spearman and Torres 1994
• Specker 1985
• Spence 1956
• Spreiter and Steffen 1946
• Springer 1998
• Squires 2004
• Sreekanth 1961
• Sreenivasan 1987
• Srinathkumar 2015
• Stachiw et al 2021
• Stadler 1993
• Stallings 1981
• Standard Atmosphere - Tables 1955
• Stange 1959
• Stanisławski 2019
• Stapleford and Teper 1965
• Stapleton et al 1997
• Stark 1985
• Starr 1977
• Stauffer and Hoblit 1973
• Stein 2005
• Stein et al 2005
• Stein et al 2007
• Steinhoff 2002
• Stengel 1980
• Stephenson and Whitfield 1970
• Stepner and Mehra 1974
• Stern and Chu 1963
• Sterne 1958
• Stevens 1985
• Stevens 1987
• Stevens et al 1966
• Stewart 1980
• Stewart 1992
• Stollery and Dyer 1989
• Stollery and Murthy 1977
• Stolyarov and Jamal-Eddine 2023
• Stone and Piland 1991
• Stone and Piland 1993
• Stone et al 1991
• Stottier 1995
• Strand et al 1967
• Strand et al 1967
• Streather 1975
• Streb 1973
• Strutz 1972
• Stubbs 1963
• Stubbs 1966
• Study of the influence of size of a manned lifting body entry vehicle on research potential and cost. Part II - Research 1967
• Su and Liu 2025
• Su and Liu 2025
• Su and Wang 2015
• Su et al 2021
• Su et al 2021
• Su et al 2024
• Sudha et al 2018
• Sugai 1965
• Sugiyama 1971
• Suikat et al 1989
• Sumerin and Shcheglov 2023
• Sun and Li 2021
• Sun et al 2019
• Sun et al 2020
• Sun et al 2020
• Sun et al 2025
• Sun et al 2025
• Sun et al 2026
• Sun et al 2026
• Supersonic Cruise Research 1979 1980
• Surber and Olsen 1978
• Suslov and Gagarskii 2025
• Suszyński et al 2025
• Sutcliffe 1955
• Swaim 1970
• Swaim and Connor 1968
• Swaim and Yen 1979
• Swenson et al 1983
• Swenson et al 1984
• Sánchez Muñoz et al 2024
• Sánchez-Sánchez and Izzo 2018
• Sóbester 2021
• Sözer and Kumbasar 2023
• T A Clark et al
• Tadakuma et al 2016
• Tagirov 1972
• Takahashi et al 2015
• Takallu and Williams 1984
• Talay 1992
• Talay 1992
• Talay and Stone 1991
• Tamaki and Kawai 2024
• Tambor 1960
• Tanaka 1981
• Tanaka et al 2024
• Tang 1970
• Tang 1971
• Tang and Gong 2023
• Tang and Pearson 1971
• Tang and Pearson 1973
• Tang and Wang 2017
• Tang and Yang 2025
• Tang et al 1978
• Tangler 1979
• Tanner 1972
• Tanner 1973
• Tanner 1975
• Tanner 1976
• Tanner 1990
• Tanno and Tanno 2021
• Tao et al 2016
• Tao et al 2017
• Tao et al 2018
• Tao et al 2021
• Tariq et al 2026
• Tartabini et al 2000
• Tate 1974
• Tate 1975
• Taylor 2004
• Taylor and Howard 2008
• Taylor and Yoo 2011
• Tekaslan and Atkins 2025
• Tekles et al 2017
• Tekure et al 2021
• Telli et al 2016
• Temple 2006
• Tendero Ventanas
• Tenhave et al 2026
• Teper and Stapleford 1966
• Teper et al 1981
• Terasaki 1963
• Tetlow et al 2000
• The algorithm of the color signal recognition at landing an unmanned aerial vehicle on an aircraft carrier in autonomous mode 2020
• The birth of Buran
• The Buran cosmonaut team
• The Complete Landing Gear 1989
• The Marriage of Buran 2013
• The Pursuit of Maximum Lift 1955
• The roots of Buran
• THE SPACEPLANE SPACE AGE 2002
• The study of the problem for tiltrotor landing on the platform of an unmanned vehicle 2022
• Thies 2022
• Thomas and Perlbachs 1967
• Thompson 1964
• Thompson 1966
• Thompson 1970
• Thompson 1970
• Thompson and Hull 1970
• Thompson and Smith 1982
• Thornton 1993
• Throckmorton 1981
• Throckmorton 1982
• Throckmorton 1993
• Tian et al 2015
• Tian et al 2015
• Tian et al 2015
• Tian et al 2018
• Tilvaldyev et al 2021
• Tinoco et al 1987
• Tischler and Tobias 2016
• Titov and Serebryansky 2026
• Tkalenko 1969
• Tole et al 1982
• Tomaszewski and Goraj 2019
• Tomita and Ho 2025
• Tomita et al 2022
• Toraldo et al 2023
• Torenbeek and Wittenberg 1983
• Torres and Rahai 2024
• Tournes and Johnson 1998
• Tournes and Johnson 2001
• Townend 1979
• Tran 2020
• Tran et al 2017
• Tran et al 2017
• Tran et al 2019
• Tran et al 2025
• Tran et al 2025
• Traub 2023
• Trifoni and Lafferty 2025
• Trifoni et al 2026
• Trifonov et al 2024
• Trinh et al 2018
• Tripathi and Padhi 2016
• Tripathi et al 2015
• Tripathi et al 2018
• Tripathi et al 2024
• Tritschler and O’Connor 2016
• Trobaugh et al 1980
• Trusfus and Abdullin 2021
• Tsien 1957
• Tsikalas and Dyer 1982
• Tucker 1990
• Tumino and Mancuso 2016
• Tuohy 1998
• Turk and Watts 1964
• Turk and Watts 1965
• Twisdale and Kirsten 1984
• U.S. Standard Atmosphere Supplements 1966, U.S. Standard Atmosphere Suppleme
• U.S. Standard Atmosphere, 1962
• Ueda and Dowell 1982
• Ugnenko et al 2017
• Ulukır et al 2025
• Ulybyshev 2010
• US Air Force spaceplane returns to Earth 2010
• Utkarsh R. Moholkar 2025
• Utterstrom and Kestek 1965
• V-STOL displays for approach and landing 1973
• Vagianos and Rooney 1964
• Valarezo et al 1993
• Van Baelen et al 2020
• van den Abeelen 2017
• Van Dommelen 1995
• Van Gaasbeek 1980
• Van Ghele et al 2018
• van Rooyen and Eshelby 1981
• Varshney et al 2019
• Varshney et al 2020
• Varshney et al 2022
• Vasil’ev 1966
• Vasil’evskii et al 2017
• Vassilakos et al 2011
• Veaux 1988
• Velger and Shinar 1983
• Vella
• Velligan and Svendsen 1971
• Venkatesan 1977
• Venkatesan and Krishnan 1975
• Venkatramanan et al 2021
• Verma 1991
• Verma and Kulkarni 2024
• Verma and Peyada 2020
• Vernet et al 2018
• Vetter 1966
• Vidal 1974
• Vidal et al 1961
• Viladegut 2018
• Virliani et al 2017
• Visual Approach Slope Indicator 1962
• Viswanath 1988
• Viswanath 1996
• Viviani and Pezzella 2015
• Viviani et al 2020
• Vocke and Nunez 2016
• Vorburger et al 1986
• Vorobуev et al 2020
• Váňa et al 2020
• Wacker et al 2001
• Wagner 1969
• Wagner and Watson R. 1963
• Walgemoed 2005
• Walker 1945
• Walker 1960
• Walker 1961
• Walker 1981
• Wallace and Gray 1963
• Walpot et al 2011
• Walsh 1990
• Walsh et al 1989
• Walton et al 1964
• Walvekar and Chakravarthy 2023
• Walyus and Dalton 1991
• Wan and Cm 2017
• Wan et al 2026
• Wang 1963
• Wang 2016
• Wang 2017
• Wang 2019
• Wang 2022
• Wang and Chen 2024
• Wang and Mou 2025
• Wang and Ting 1961
• Wang and Wang 2024
• Wang and Wu 2016
• Wang and Zhang 2022
• Wang and Zhou 2022
• Wang et al 2016
• Wang et al 2017
• Wang et al 2018
• Wang et al 2018
• Wang et al 2019
• Wang et al 2019
• Wang et al 2020
• Wang et al 2020
• Wang et al 2020
• Wang et al 2020
• Wang et al 2020
• Wang et al 2022
• Wang et al 2022
• Wang et al 2022
• Wang et al 2022
• Wang et al 2022
• Wang et al 2022
• Wang et al 2022
• Wang et al 2022
• Wang et al 2022
• Wang et al 2022
• Wang et al 2022
• Wang et al 2023
• Wang et al 2023
• Wang et al 2023
• Wang et al 2024
• Wang et al 2024
• Wang et al 2024
• Wang et al 2024
• Wang et al 2024
• Wang et al 2024
• Wang et al 2025
• Wang et al 2025
• Wang et al 2026
• Ward 1968
• Ware 1989
• Ware 1989
• Ware and Cruz 1993
• Ware and Cruz 1993
• Ware et al 1991
• Warner 1981
• Warner and Wilcox 1972
• Wartemann et al 2018
• Washington et al 1968
• Wasicko 1972
• Wasserman and Mitchell 1973
• Watson et al 1981
• Watson et al 1983
• Watson et al 1986
• Weber et al 2000
• Webster 1947
• Wei et al 2019
• Wei et al 2020
• Wei et al 2024
• Wei et al 2025
• Weidner et al 1976
• Weiland 2021
• Weilmuenster and Greene 1993
• Weilmuenster et al 1990
• Weilmuenster et al 1991
• Weingarten 1984
• Weingarten and Chalk 1983
• Weingarten and Chalk 1984
• Weingarten et al 1986
• Weingarten et al 1986
• Weiser et al 2020
• Weiss and Giani 2024
• Weisshaar 1978
• Wells 1985
• Wells 2014
• Wenqian et al 2016
• Wetzel
• Whitaker and Rediess 1970
• White 1963
• White 1971
• White 1977
• Whitener 1979
• Whitfield and Griffith 1963
• Whitfield and Potter 1966
• Whitmore and Moes 1999
• Whitmore et al 1994
• Whitmore et al 2001
• Whitmore et al 2005
• Whoric 1977
• Wibben and Furfaro 2016
• Wickens and Dixon 2002
• Widnall and Morth 1972
• Wierwille and Connor 1983
• Wilcox and Chamberlin 1974
• Wilcox and Chamberlin 1975
• Wilhelm and Schafranek 1986
• Williams and Curry 1983
• Williamson Jr. 1963
• Willshire et al 1993
• Wilmott 1986
• Wilson et al 1993
• Wimpress 1966
• Windsor 1962
• Winograd and Miles 1956
• Witcher et al 2018
• Witte et al 2016
• Wolf 1971
• Wolf 1996
• Wolf et al 2011
• Wolkovitch 1984
• Woloshen 1974
• Wong et al 1958
• Wong et al 2020
• Wood 1968
• Wood 1972
• Wood and Covell 1985
• Woodbury and Valasek 2016
• Woods and Friswell 2015
• Woodward 1956
• Woolf 2012
• Wootton 1967
• Worth Assessments of Approach to Landing 1977
• Wrestler and Clifton G. 1965
• Wright and Lappos 1981
• Wu 1984
• Wu and Kareem 2015
• Wu and Zhang 2023
• Wu and Zhu 2024
• Wu et al 2016
• Wu et al 2016
• Wu et al 2017
• Wu et al 2023
• Wu et al 2024
• Wu et al 2026
• Wurster and Stone 1993
• XCOR, Developing the Next Generation Spaceplane 2016
• Xia and Yu 1988
• Xia et al 2024
• Xiangzhang et al 2024
• Xiao et al 2020
• Xiao et al 2024
• Xie and Cheng 2015
• Xie and Xu 2024
• Xing et al 2024
• Xiong et al 2022
• Xiu et al 2024
• Xu 2005
• Xu and Lan 2018
• Xu and West 1990
• Xu et al 2016
• Xu et al 2017
• Xu et al 2019
• Xu et al 2019
• Xu et al 2022
• Xu et al 2022
• Xu et al 2023
• Xu et al 2025
• Xu et al 2025
• Xu et al 2025
• Xu et al 2025
• Xu et al 2025
• Xue and Yu 2016
• Xue et al 2023
• Xue et al 2024
• Yadav et al 2018
• Yajnik and Subbaiah 1976
• Yamada and Suzuki 2016
• Yan and He 2015
• Yan and He 2020
• Yan et al 2018
• Yan et al 2023
• Yang 1971
• Yang 2021
• Yang 2025
• Yang and Zha 2016
• Yang et al 2015
• Yang et al 2016
• Yang et al 2016
• Yang et al 2018
• Yang et al 2020
• Yang et al 2021
• Yang et al 2023
• Yang et al 2024
• Yang et al 2024
• Yang et al 2025
• Yang et al 2026
• Yang et al 2026
• Yao and Xin 2023
• Yao et al 2019
• Yao et al 2024
• Yao et al 2025
• Yaravintelimath et al 2016
• Yarusevych and Kotsonis 2016
• Yasue 2020
• Yates 1966
• Yates and Donald 1986
• Ye 2015
• Ye et al 2015
• Yechout 1988
• Yeo and Johnson 2015
• Yildiz and Dandil 2018
• Yin and Wang 2017
• Yin et al 2025
• Yoon and Suzuki 2024
• Yoon et al 2016
• Young 1982
• Young and Underwood 1982
• Young and Underwood 1983
• Yu et al 2016
• Yu et al 2020
• Yu et al 2022
• Yu et al 2023
• Yuan and Li 2019
• Yuan et al 2022
• Yuan et al 2022
• Yue et al 2018
• Yue et al 2018
• Yue et al 2019
• Yue et al 2022
• Yue et al 2022
• Yue et al 2025
• Yurttav et al 2025
• Yuta Akai et al 2007
• Zaal et al 2015
• Zaal et al 2018
• Zaal et al 2019
• Zafirov 2019
• Zajdel et al 2022
• Zaki 2014
• Zanoni et al 2022
• Zaprianov et al 1987
• Zaragoza Prous et al 2025
• Zarin 1965
• Zarin 1966
• Zauner et al 2023
• Zaytseva et al 2021
• Zewge and Bang 2023
• Zhai and Yang 2020
• Zhai et al 2025
• Zhang 1992
• Zhang 2023
• Zhang 2024
• Zhang 2024
• Zhang 2024
• Zhang 2025
• Zhang and Wang 2024
• Zhang et al 2008
• Zhang et al 2015
• Zhang et al 2017
• Zhang et al 2017
• Zhang et al 2017
• Zhang et al 2017
• Zhang et al 2018
• Zhang et al 2019
• Zhang et al 2019
• Zhang et al 2019
• Zhang et al 2019
• Zhang et al 2021
• Zhang et al 2021
• Zhang et al 2022
• Zhang et al 2022
• Zhang et al 2022
• Zhang et al 2024
• Zhang et al 2024
• Zhang et al 2025
• Zhang et al 2025
• Zhang et al 2025
• Zhang et al 2025
• Zhang et al 2025
• Zhang et al 2026
• Zhang et al 2026
• Zhao et al 2014
• Zhao et al 2020
• Zhao et al 2020
• Zhao et al 2023
• Zhao et al 2023
• Zhao et al 2025
• Zhen et al 2018
• Zhen et al 2019
• Zhen et al 2020
• Zheng and Liu 2018
• Zheng et al 2014
• Zheng et al 2017
• Zheng et al 2026
• Zhesheng Jiang and Ordonnez 2007
• Zhi et al 2015
• Zhicong and Voronko 2023
• Zhong et al 2018
• Zhong et al 2019
• Zhou 2026
• Zhou and Wang 2023
• Zhou et al 2015
• Zhou et al 2017
• Zhou et al 2019
• Zhou et al 2021
• Zhou et al 2025
• Zhu 2022
• Zhu and Duan 2015
• Zhu and Morrison 2021
• Zhu et al 2025
• Zhu et al 2026
• Zhu et al 2026
• Zosimovych 2022
• Zou and Meng 2019
• Zou et al 2024
• Zou et al 2026
• Zumwalt and Tang 1963
• Zuppardi 2021
• Zuppardi and Mongelluzzo 2023
• Zuppardo 1993
• Zwieback 1964
• Çelik and Demirezen 2024
• Çelik and Sánchez 2017
• Çeti̇n et al 2024
• Бабич et al 2017
• Завальная and Бурнашев 2015
• Панасюк et al 2018, Integral aerodynamic design of an
• Чжан et al 2022