The X-38 was built to bring seven people down from the International Space Station in an emergency, and it flew the X-24A shape to do it. Then it threw the runway away. This is the thirty-ninth article 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, the X-23, the X-24, the X-25, the X-26, the X-27, the X-28, the X-29, the X-30, the X-31, the X-32, the X-33, the X-34, the X-35, the X-36, and the X-37.

Five vehicles earlier in this series led up to the horizontal landing and this one was built to abandon it. The X-23 proved a lifting entry could be steered to a point. The X-24 spent its entire life characterising the unpowered approach. The X-33 and X-34 were sized around runway operations, and the X-37 made an autonomous runway landing routine. The X-38 flies the same lifting body family of shape through entry and then comes down under seven hundred square metres of ram-air canopy onto whatever flat ground is available. The space agency’s account of the programme describes it in those terms.

This is not a smaller ambition but a different answer to a question the series has been asking since the X-23, and the question is what a runway costs.

The Research Question

Why a Station Needs a Lifeboat at All

A crew aboard a space station cannot walk home. If somebody suffers a medical emergency, if the station is damaged, or if the vehicle that brought them is unavailable, the only way down is a vehicle already docked and waiting [NASA X-38]. The requirement is not performance but availability, and a vehicle that spends years attached to a station doing nothing is judged by what it costs to have rather than by what it does.

Seven seats is the number that makes the requirement bite. The station’s design complement was seven, the Soyuz that served as the interim lifeboat carried three [NASA X-38] [Soyuz spacecraft], and a station cannot hold more people than it can evacuate. The crew size of the station and the seat count of its lifeboat are the same number, which is why this vehicle exists at all and why it is as large as it is [NASA X-38].

The Question This Article Asks

What does a runway landing cost a returning vehicle, and what does giving it up buy? Both sides are computable from published numbers, and the answer turns out to be a single ratio that this article spends its length unpacking.

Why the Runway Is the Expensive Choice

A runway landing demands four things at once. It demands speed, because a lifting body must fly fast enough to generate lift on a small wing. It demands a runway, a long prepared strip that somebody must own and maintain [Wingless flight]. It demands crossrange, because there are few such strips and the vehicle must be able to reach one from wherever the orbit happens to put it. And it demands that the vehicle fly, with the control authority, the landing gear and the handling qualities that implies.

A parafoil demands none of the four. It touches down at about forty miles per hour, or about eighteen metres per second, it needs a field where a lifting body needs a strip, it needs almost no crossrange because fields are everywhere, and it does not need the vehicle to fly at all once the canopy is out [Wingless flight].

Programme Origin

An Interim Answer That Would Not Scale

The station’s early operations relied on a docked Soyuz as the escape vehicle, and a Soyuz seats three. A permanently crewed station of seven therefore needed either three Soyuz vehicles or one purpose-built lifeboat [NASA X-38].

The programme began at the Johnson Space Center in early 1995 as a technology demonstration for a Crew Return Vehicle. It was deliberately structured as a fast and cheap effort, using commercial hardware where it could and an aerodynamic shape that already existed [NASA account of the X-38 prototype crew return vehicle].

Why the Shape Was Borrowed

The X-24A shape was chosen because its aerodynamics were already known, having been flown twenty-eight times between 1969 and 1971 [Martin Marietta X-24A] [NASA account of the X-38 prototype crew return vehicle]. That is an unusually direct inheritance for an X-plane, and it saved the programme the cost of developing a new spacecraft shape [Wingless flight]. It did not save the wind-tunnel work, because the shape was enlarged and its rear thickened for the Crew Return Vehicle [NASA X-38], and the enlarged shape was tested again at low speed and at hypersonic speed [Komerath, N. M. et al 1998] [Horvath, Thomas J. et al 2000].

Who Built the Airframes

Scaled Composites built the atmospheric test airframes [NASA account of the X-38 prototype crew return vehicle], which is why the designation carries that name, while the space agency integrated the systems and the European Space Agency and the German Aerospace Center took part in the programme [NASA X-38]. International participation in an X-plane is unusual and follows from the station being international, since the vehicle existed to serve a station that Europe helped build [NASA X-38].

The Window This Article Calls the Period

The programme ran from 1995 to its cancellation on 29 April 2002 [NASA X-38], and this article calls that window plus a few years of settling the period, taking the cutoff at 2006. Everything after is contemporary. The reference counts reported later use exactly that boundary.

Sizing From First Principles

Notation

Parachute engineering and flight mechanics each own a set of symbols and the two overlap. The ambiguous cases are marked here, so that none is resolved silently at each use.

Symbol Meaning The other standard use, avoided here
$S$ canopy area the wing reference area, which does not appear. The drogue is $S_{d}$
$\delta$ glide angle below the horizontal  
$C_{R}$ resultant force coefficient  
$n$ scaling exponent the crew count, written $c$, and the load factor, written in $g$ throughout
$\Lambda$ opening-shock factor  
$V$ a speed under the canopy $v$, which is every other speed, including the runway and orbital ones
$a$ semi-major axis acceleration, which always carries a bar or a subscript
$h$ an altitude $H$, which is the atmospheric scale height
$e$ the base of the natural logarithm eccentricity, which does not appear
$L/D$ a ratio used for two different aerodynamics. The canopy glides at 3 and the vehicle enters at about 0.8, and every use says which  

What the Landing System Has to Absorb

The argument fits in one number, and what follows elaborates it.

A lifting body arriving on a runway touches down at something near ninety metres per second, since the powered lifting bodies landed at about 200 miles per hour [NASA account of the lifting bodies]. The kinetic energy that the landing system, the brakes and the runway between them must dissipate is

\[E = \tfrac{1}{2} m v^{2}\]

which for the 11,340 kilogram vehicle at that speed is 45.93 megajoules.

The same mass under a ram-air canopy arrives differently. A gliding canopy in steady descent balances weight against the resultant aerodynamic force rather than against lift alone. A ram-air canopy is a wing rather than a drag device, so the airspeed follows from a resultant coefficient,

\[C_{R} = C_{L} \sqrt{1 + \frac{1}{(L/D)^{2}}}, \qquad V = \sqrt{\frac{2 W}{\rho S C_{R}}}\]

and the two components follow from the glide angle, which is fixed by the glide ratio alone,

\[\delta = \arctan \frac{1}{L/D},\] \[V_{\text{vertical}} = V \sin \delta = \frac{V}{\sqrt{1 + (L/D)^{2}}}, \qquad V_{\text{horizontal}} = V \cos \delta = (L/D) \, V_{\text{vertical}}.\]

At a glide ratio of three that angle is 18.43 degrees below the horizontal.

Taking a lift coefficient of 0.80 and a glide ratio of 3, which are ordinary for a large ram-air canopy, the 11,340 kilogram vehicle under 696.8 square metres of canopy descends at 17.58 metres per second of airspeed, with 16.68 forward and 5.56 down. Its kinetic energy is 1.752 megajoules.

The ratio is 26.2 to one, and the mass cancels out of it entirely, so the ratio is the square of the speed ratio and depends on no property of the vehicle at all.

\[\frac{E_{\text{runway}}}{E_{\text{parafoil}}} = \left( \frac{v_{\text{runway}}}{V} \right)^{2} = 26.2\]

That is what the runway costs. A vehicle that lands horizontally arrives carrying twenty-six times the energy of one that lands under a canopy, and every part of the airframe that touches the ground has to be built for it.

How Much of That Rests on the Assumed Lift Coefficient

The lift coefficient of 0.80 is the least defensible input in this article, so its sensitivity is computed separately. It appears once, under a radical, so every speed varies as

\[V \propto C_{L}^{-1/2}\]

and the parafoil’s kinetic energy therefore as $C_{L}^{-1}$, which makes the energy ratio vary as the first power,

\[\frac{E_{\text{runway}}}{E_{\text{parafoil}}} \propto C_{L}.\]
Lift coefficient Sink rate Against 0.80 Energy ratio
0.60 6.42 metres per second plus 15.5 percent 19.7
0.80 5.56 metres per second reference 26.2
1.00 4.97 metres per second minus 10.6 percent 32.8

The individual sink rates move and the conclusion does not. A factor of 1.67 across the plausible range of the coefficient moves the ratio between 19.7 and 32.8, and the argument needs only that the ratio is large.

The Flare, and an Identity That Needs No Assumption

A parafoil arrests its descent at the last moment by pulling both control lines, raising the angle of attack and converting forward motion into a transient increase in lift. The question is whether there is enough forward motion to do it with, and the answer needs nothing assumed.

In steady glide the horizontal speed is the vertical multiplied by the glide ratio, so the two kinetic energies stand in the ratio

\[\frac{E_{\text{horizontal}}}{E_{\text{vertical}}} = \frac{\tfrac{1}{2} m V_{\text{horizontal}}^{2}}{\tfrac{1}{2} m V_{\text{vertical}}^{2}} = (L/D)^{2}\]

exactly, with no mass, no area and no air density appearing. At a glide ratio of three the forward motion carries 9.0 times the energy of the descent.

Glide ratio Forward energy against vertical
2.0 4.0 times
3.0 9.0 times
4.0 16.0 times

The flare is therefore never limited by energy. It is limited by how quickly the canopy can convert that energy into lift before it stalls, a question about the canopy and not about the arithmetic. Converting only five percent of what is available takes the sink rate from 5.56 to 4.12 metres per second. If the canopy turns a fraction $\eta$ of the forward energy into arrested descent, then since the forward energy is $(L/D)^{2}$ times the vertical, the vertical energy falls to $1 - \eta (L/D)^{2}$ of its value, and with the unrounded sink rate of 5.559 metres per second

\[V_{\text{vertical}}' = V_{\text{vertical}} \sqrt{1 - \eta \, (L/D)^{2}} = 5.559 \sqrt{1 - 0.05 \times 9} = 4.12 \text{ metres per second}.\]

What a Touchdown Costs the Occupants

A vertical arrival arrested over a stroke $s$ imposes a mean deceleration

\[\bar{a} = \frac{V_{\text{vertical}}^{2}}{2 s}.\]
Arresting stroke Deceleration at 5.56 metres per second
15 centimetres 10.50 g
30 centimetres 5.25 g
60 centimetres 2.63 g
100 centimetres 1.58 g

After a flare to 4.12 metres per second the same thirty centimetres gives 2.89 g,

\[\frac{\bar{a}}{g_{0}} = \frac{(4.122 \text{ m/s})^{2}}{2 \times 0.30 \text{ m} \times 9.80665 \text{ m/s}^{2}} = 2.89,\]

where $g_{0}$ is standard gravity and 4.122 metres per second is the unrounded flared sink rate.

The runway case is not this calculation and the difference matters. A runway landing does not arrest the vehicle in an impact. It rolls out over hundreds of metres, and the rollout is why it needs a runway. Arresting ninety metres per second in thirty centimetres would be 1,376.6 g, which is not a landing but a crash,

\[\frac{\bar{a}}{g_{0}} = \frac{(90 \text{ m/s})^{2}}{2 \times 0.30 \text{ m} \times 9.80665 \text{ m/s}^{2}} = 1{,}376.6.\]

The parafoil converts a distance problem into a stroke problem, and a stroke of half a metre is something a seat and a crushable structure can provide while a runway is something a nation must build.

Why the Canopy Had to Be the Largest Ever Flown

The canopy carries a wing loading of 159.6 newtons per square metre, which is 16.27 kilograms per square metre or 3.33 pounds per square foot,

\[\frac{W}{S} = \frac{11{,}340 \times 9.80665}{696.8} = 159.6 \ \text{N/m}^{2}, \qquad \frac{m}{S} = \frac{11{,}340}{696.8} = 16.27 \ \text{kg/m}^{2}, \qquad \frac{25{,}000 \ \text{lb}}{7{,}500 \ \text{ft}^{2}} = 3.33 \ \text{lb/ft}^{2}.\]

Most student skydivers start between 0.7 and 0.9 pounds per square foot, and experienced jumpers fly between 1.1 and 1.8 [Wingload Calculator, Skydive Perris]. So this canopy is loaded 3.7 to 4.8 times as heavily as a student’s and 1.9 to 3.0 times as heavily as an experienced jumper’s,

\[\frac{3.333}{0.9} = 3.70, \quad \frac{3.333}{0.7} = 4.76, \qquad \frac{3.333}{1.8} = 1.85, \quad \frac{3.333}{1.1} = 3.03.\]

The area follows from the sink rate the designer will accept, and it follows steeply. Inverting the glide relation for area,

\[S = \frac{2 W}{\rho \, C_{R} \, V^{2}} \qquad\text{with}\qquad V = V_{\text{vertical}} \sqrt{1 + (L/D)^{2}}\]

so the area needed varies as the inverse square of the sink rate.

Sink rate demanded Canopy area Against the flown canopy
3.0 metres per second 2,392.3 square metres 343.3 percent
4.0 metres per second 1,345.7 square metres 193.1 percent
5.0 metres per second 861.2 square metres 123.6 percent
6.0 metres per second 598.1 square metres 85.8 percent

Wanting one metre per second less costs half as much canopy again. This relation made the canopy the largest parafoil ever made [NASA X-38], and it means the record came out of the requirement. The programme did not set out to break it.

But the Crew Count Sets the Mass Only at the Margin

The obvious next step is to say that seven seats made the vehicle heavy and the heavy vehicle made the canopy large. The claim is only partly true, and the arithmetic shows by how much.

The model is stated because it is doing real work. Taking a fraction $\phi$ of the empty mass as independent of the crew, being the airframe, the heat shield, the deorbit stage and the avionics, and scaling the remainder with the seat count $c$,

\[m(c) = m_{\text{empty}} \left( \phi + (1 - \phi) \frac{c}{c_{\max}} \right) + m_{\text{crew}} \, c\]

with $\phi$ taken as 0.55 and $m_{\text{crew}}$ as 97.3 kilograms. Anchoring on the sink rate of the flown canopy, so that the seven-crew row reproduces the flown area by construction,

Crew Approximate mass Canopy area Against the flown canopy
1 6,645 kilograms 408.3 square metres 58.6 percent
3 8,210 kilograms 504.5 square metres 72.4 percent
5 9,775 kilograms 600.6 square metres 86.2 percent
7 11,340 kilograms 696.8 square metres 100.0 percent

A single-seat version would still have needed 58.6 percent of the canopy, because the airframe, the heat shield, the avionics and the deorbit stage do not shrink with the crew. At a fixed sink rate the area relation makes area proportional to mass, so

\[\frac{S(1)}{S(7)} = \frac{m(1)}{m(7)} = \frac{6{,}645}{11{,}340} = 0.586.\]

Six of the seven seats cost about forty percent of the canopy area, and the fixed overhead costs the rest.

The fixed fraction is assumed and the conclusion survives every plausible value of it.

Fixed fraction Single-seat mass Canopy needed
0.40 5,275 kilograms 46.5 percent
0.55 6,645 kilograms 58.6 percent
0.70 8,015 kilograms 70.7 percent

Even at the most generous assumption a single-seat vehicle needs nearly half the canopy, so the statement that the crew count sets the mass only at the margin does not depend on the value chosen.

Five Stages of Reefing and the Model That Cannot Explain Them

The flown system inflated the canopy in five reefed stages [NASA X-38]. The obvious explanation is that a single-step inflation would injure the crew, and that explanation does not survive being written down.

Where that deployment speed comes from needs asking first, because the vehicle is released at several hundred kilometres per hour and a ram-air canopy cannot be opened anywhere near that [NASA X-38]. A drogue brings it down first, and the area needed follows from the steady descent condition,

\[S_{d} = \frac{2 W}{\rho \, C_{D} \, V_{\text{target}}^{2}}.\]
Target speed Drogue area at a drag coefficient of 0.55
24 metres per second 573.1 square metres
27 metres per second 452.8 square metres
32 metres per second 322.4 square metres

The drogue this model asks for is a large parachute too, at 452.8 square metres or 65.0 percent of the main canopy,

\[\frac{S_{d}}{S} = \frac{452.8}{696.8} = 0.650.\]

The flown drogue was smaller, at 60 feet in diameter [NASA’s X-38 crew rescue craft tests road to Earth], which is about 263 square metres of nominal area, and the same release gives the speed it reached as about 70 miles per hour.

The descent system therefore needs two large decelerators in sequence, and the second cannot be opened until the first has done its work.

At a deployment speed near twenty-seven metres per second, the 60 miles per hour that the encyclopaedia gives [NASA X-38], the dynamic pressure is

\[q = \tfrac{1}{2} \rho V^{2} = 446.5 \text{ pascals}\]

and a fully inflated canopy of 696.8 square metres at a drag coefficient of 0.75 would pull

\[F = q \, S \, C_{D} = 233.3 \text{ kilonewtons},\]

which on 11,340 kilograms is 2.10 g steady. Inverting for the area a deceleration limit admits,

\[S_{\text{admissible}} = \frac{m \, g_{\text{limit}} \, g_{0}}{q \, C_{D}}\]

gives 996.2 square metres at three g, or 1.43 times the flown canopy.

The model says one stage and the flown system used five.

Inverting for the speed at which the steady load would bite is more informative than the area, and it attaches a margin to the claim instead of leaving the reader to assume one is large,

\[V_{\text{limit}} = \sqrt{\frac{2 \, m \, g_{\text{limit}} \, g_{0}}{\rho \, S \, C_{D}}}.\]
Deceleration limit Speed at which the full canopy reaches it Against the deployment speed
2 g 26.36 metres per second 0.98 times
3 g 32.28 metres per second 1.20 times
5 g 41.68 metres per second 1.54 times

The margin is only about twenty percent in speed at a three g limit, and at a two g limit there is no margin at all. That qualification matters, so the article states it alongside the three g figure.

Adding an opening-shock factor does not close the gap either, since even at the high end of the usual range,

\[F_{\text{peak}} = \Lambda \, q \, S \, C_{D}, \qquad \Lambda \in [1.5, 2.5]\]

the peak reaches 5.25 g, which a seated and restrained crew survives.

The failed calculation places the constraint away from the crew. A canopy of this size cannot inflate uniformly. The centre cells fill first, the load concentrates on a fraction of the suspension lines, and the structure that limits the inflation is the canopy. Reefing exists to make the inflation orderly rather than to make it gentle, and no vehicle-level load model can predict the stage count because the stage count is not a vehicle-level quantity.

A forward calculation that fails by this margin is a finding about the model and not a reason to discard it. It identifies which physics the simple treatment omits.

The Crossrange Argument Turned Inside Out

The lifting-entry vehicles earlier in this series, among them the X-23 and the X-37, treat crossrange as a figure of merit. The X-38 shows that it was never a figure of merit. It was the price of insisting on a runway.

A parafoil steers only within its glide cone from the point of deployment. The reach is height traded for distance at the glide ratio,

\[R = \left( \frac{L}{D} \right) h,\]

into which neither mass nor area nor air density enters, and at a glide ratio of three from six kilometres it is 18.0 kilometres. The X-37 article computed 1,397.8 kilometres of entry crossrange for a runway lander at a hypersonic lift-to-drag ratio near 1.1. The ratio is 77.7 to one and it looks devastating until the question is asked the other way round.

Crossrange exists to reach a runway, and runways are rare. A vehicle that may land on any flat ground needs the footprint only to choose between nearby fields, and the deorbit burn does the rest of the work by choosing when to leave orbit.

Landing sites available Number Reachable per day at an 18 kilometre footprint
Runways certified for a lifting body 3 0.1
Airfields of adequate length 200 4.0
Flat unobstructed areas 20,000 396.1

The last row is the answer. A vehicle that needs a certified runway gets an opportunity every ten days. A vehicle that needs a flat field gets four hundred a day. The trade gains a factor of several thousand in availability for a factor of seventy-eight in crossrange, and for a lifeboat availability is the entire requirement.

These are order-of-magnitude figures and the article claims nothing finer. The site counts are illustrative and the reachability model treats sites as uniformly distributed. What survives the crudeness is the direction and the scale of the trade, which is all the argument needs.

Dependent Systems

The Untested Entry

The vehicle deorbits from a station orbit near four hundred kilometres [International Space Station]. Lowering perigee far enough to guarantee entry costs

\[v = \sqrt{\mu \left( \frac{2}{r} - \frac{1}{a} \right)}, \qquad a = \frac{r_{a} + r_{p}}{2}\]

so that lowering perigee from a circular orbit costs the difference between the circular speed and the speed on the transfer at the same radius,

\[\Delta v = \sqrt{\frac{\mu}{r_{a}}} - \sqrt{\mu \left( \frac{2}{r_{a}} - \frac{1}{a} \right)} = 132.8 \text{ metres per second},\]

a task that fell to the deorbit propulsion stage that GenCorp Aerojet was developing for V-201 [NASA account of the X-38 prototype crew return vehicle].

The deceleration that follows is what the crew feels, and for a shallow entry it is nearly independent of the vehicle. The Allen and Eggers result for a ballistic entry gives the peak as

\[a_{\text{peak}} = \frac{v_{e}^{2} \sin \gamma_{e}}{2 e H}\]

where $H$ is the density scale height and $\gamma_{e}$ the entry flight path angle, and the ballistic coefficient does not appear at all. At an entry speed of 7,800 metres per second and a path angle of 1.4 degrees this is 3.87 g. Lift relieves part of it, by the factor by which the vertical force balance is eased,

\[k = \frac{1}{\sqrt{1 + (L/D)^{2}}}, \qquad a_{\text{lifting}} = k \, a_{\text{peak}}\]

which at a lift-to-drag ratio of 0.8 is 0.7809.

Lift-to-drag ratio Relief factor Peak with relief
0.4 0.9285 3.60 g
0.8 0.7809 3.02 g
1.2 0.6402 2.48 g

A deconditioned or injured crew is why this matters. The vehicle exists to bring down somebody who may be ill, and a body that has spent months in free fall has lost plasma volume, bone and cardiac conditioning through the well documented effects of spaceflight on the human body. The entry load is a medical constraint rather than a structural one, a sentence that could not be written about any other vehicle in this series.

Thermal Protection

Aerothermodynamics of a Blunt Lifting Body

Hypersonic and Low-Speed Aerodynamics of the Shape

The X-24A shape was flown twenty-eight times [Martin Marietta X-24A] and carried from Mach 2 down to a subsonic landing, and that record is why it was chosen [Wingless flight]. The X-38 began from a shape already proven in flight, and the enlarged shape was still characterised in wind tunnels at low speed and at Mach 6, 10 and 20 [Komerath, N. M. et al 1998] [Horvath, Thomas J. et al 2000].

Guidance, Navigation and the Autonomous Descent

The vehicle flies itself throughout. What is unusual is not the autonomy but where it ends. A runway lander must fly an autonomous approach to a fixed strip. A parafoil lander must only reach a chosen field and then flare, and the guidance problem is the one the guided airdrop community had already been solving for cargo [NASA account of the X-38 prototype crew return vehicle].

Landing Loads and the Structure That Takes Them

Parachute and Decelerator Systems Generally

The Deorbit Stage and Orbital Operations

The Station the Vehicle Served

Structure, Scale and a Shape That Grew

The X-38 inherited the X-24A outer mould line, enlarged it and thickened its rear [NASA X-38]. Measuring the exponent that relates the two, for a quantity $Q$ and a length $\ell$,

\[Q \propto \ell^{\,n} \qquad \Longrightarrow \qquad n = \frac{\ln \left( Q_{1} / Q_{2} \right)}{\ln \left( \ell_{1} / \ell_{2} \right)}\]
Quantity X-24A X-38 Crew Return Vehicle Ratio
Length 7.315 metres 9.14 metres 1.249
Launch mass 5,443 kilograms 11,340 kilograms 2.083

The inputs are sourced as follows. The X-24A is approximately 24 feet long, 7.315 metres [Pilot safety for the X-24A lifting body vehicle]. The programme’s history gives approximately 12,000 pounds at launch, 5,443 kilograms [Wingless flight], and the table uses it as the launch mass. No source consulted states the launch weight more precisely. The Crew Return Vehicle is 30 feet long with a gross weight of 25,000 pounds, which are 9.14 metres and 11,340 kilograms [NASA X-38].

Mass scales as length to the 3.295 against 3 for geometric similarity. A geometrically similar X-24A grown to 9.14 metres would mass 10,618 kilograms, and the X-38 masses 11,340, a factor of 1.068,

\[n = \frac{\ln (11{,}340 / 5{,}443)}{\ln (9.14 / 7.315)} = \frac{\ln 2.0834}{\ln 1.2495} = 3.295, \qquad m_{\text{similar}} = 5{,}443 \times 1.2495^{3} = 10{,}618 \ \text{kg}, \qquad \frac{11{,}340}{10{,}618} = 1.068.\]

The exponent stays above 3 across the uncertainty in both inputs. The vehicle’s builder gives approximately 5,500 pounds empty with tankage for approximately 5,500 pounds of propellants and gases [Pilot safety for the X-24A lifting body vehicle], about 11,000 pounds or 4,990 kilograms. A NASA study of lifting-body lift and drag tabulates the X-24A as 24.50 feet long, 7.468 metres [In-Flight Subsonic Lift and Drag Characteristics Unique to Blunt-Based Lifting Reentry Vehicles]. Taking each in turn,

\[n_{11{,}000\ \text{lb}} = \frac{\ln (11{,}340 / 4{,}990)}{\ln 1.2495} = 3.69, \qquad n_{24.5\ \text{ft}} = \frac{\ln 2.0834}{\ln (9.14 / 7.468)} = 3.63,\]

and both exceed 3. The margin over geometric similarity is real but modest, and its size hinges on approximate figures for a vehicle whose launch weight no source gives exactly.

The shape was inherited and the mission was not. The X-24A carried one pilot and a rocket engine [Martin Marietta X-24A]. The X-38 carries seven people, life support, a thermal protection system and a deorbit stage [NASA account of the X-38 prototype crew return vehicle], and the mass grew faster than the geometry because the payload grew faster than the airframe.

The sign is the opposite of the previous article’s, and the two are best read as a pair. The X-37 shrank from the Shuttle orbiter with mass falling as length to the 1.924, more slowly than volume, because a small reusable vehicle keeps its fixed overhead. The X-38 grew from the X-24A with mass rising as length to the 3.295, faster than volume, because the mission grew faster than the machine. Neither pair is geometrically similar and the reasons differ, so a scaling exponent should not be read as a trait of the technology.

The comparison has to be drawn within the lifting-body line, since no two members of that line were built for the same job.

The Flight Test Record

What Flew

Three atmospheric vehicles flew and the orbital vehicle never did. [NASA account of the X-38 prototype crew return vehicle] [NASA X-38]

Vehicle What it was Fate
V-131 Full aerodynamic scale of the X-24A shape Drop tests from a B-52
V-132 As V-131, later configuration Drop tests, including the highest and fastest
V-131R Rebuilt at 80 percent of the Crew Return Vehicle Drop tests with the full-size parafoil
V-201 The orbital vehicle 90 percent complete, never flown

The drop tests released the vehicle from the wing pylon of a B-52 at altitudes between 7,600 and 13,700 metres, being 25,000 and 45,000 feet, over the lakebed at what is now the Armstrong Flight Research Center [NASA account of the X-38 prototype crew return vehicle]. In March 2000 V-132 was released at 11,900 metres, being 39,000 feet, and exceeded 800 kilometres per hour, being 500 miles per hour, before deploying its parachutes. The Dryden news release gives its free flight as 44 seconds and the centre’s photograph caption as 45 [NASA’s X-38 crew rescue craft tests road to Earth] [X-38 Arrival at NASA Dryden on June 4, 1997]. V-201 was 90 percent complete when the project’s cancellation was announced on 29 April 2002 [NASA X-38]. The vehicles were dropped, they flew a short unpowered profile, and then the decelerator system took over.

What the Drop Tests Could and Could Not Show

The atmospheric vehicles are 81.7 percent of the orbital vehicle by length, being 24.5 feet long [NASA account of the X-38 prototype crew return vehicle] against 30,

\[\frac{\ell_{\text{atmospheric}}}{\ell_{\text{orbital}}} = \frac{24.5 \ \text{ft}}{30 \ \text{ft}} = 0.817,\]

and they flew at between 15,000 and 24,000 pounds, which are 6,804 and 10,886 kilograms, against its 11,340 [NASA X-38]. The 24,000 pound maximum is the encyclopaedia’s figure. The NASA account gives only that vehicle weights range from 15,000 pounds to about 25,000 pounds, in a passage that introduces the orbital V-201 immediately after, so it does not separate the drop-test vehicles from the orbital one [NASA account of the X-38 prototype crew return vehicle]. Under the same canopy the difference is small in the quantity that matters.

Mass under the full canopy Sink rate
6,804 kilograms 4.31 metres per second
10,886 kilograms 5.45 metres per second
11,340 kilograms, the orbital vehicle 5.56 metres per second

The heaviest drop test came within a factor of 1.021 of the orbital vehicle’s sink rate, and the reason it came so close is a square root. At fixed canopy area and fixed coefficients the glide relation leaves only the weight under the radical, so

\[V_{\text{vertical}} \propto \sqrt{m} \qquad \Longrightarrow \qquad \frac{\Delta V}{V} \approx \frac{1}{2} \frac{\Delta m}{m}.\]

A mass shortfall of 4.00 percent is therefore a sink shortfall of about 2 percent, and the landing system was tested close to its design condition. The square root is doing the work, since the same shortfall in a quantity that scaled linearly would have been twice as far from condition.

The entry was never tested at all. No X-38 ever went to orbit, no X-38 ever met the atmosphere at orbital speed, and no X-38 thermal protection system was ever exposed to entry heating in flight [NASA X-38]. The programme proved the half of the problem that could be proved from a B-52 and left the other half entirely unproven.

The Cancellation

The programme was cancelled on 29 April 2002 without producing a flown orbital vehicle. The space agency’s account gives the total projected cost to develop and flight test the X-38s as approximately 700 million dollars, against original estimates of more than two billion dollars for a capsule-type Crew Return Vehicle [NASA account of the X-38 prototype crew return vehicle]. The stated reason was the station’s own cost growth, which led to a reduced configuration without the American Crew Return Vehicle, whose crew of three could be served by the Soyuz already flying [NASA X-38].

The lifeboat was cancelled because the station shrank to fit the lifeboat it already had. The seven-seat requirement disappeared, and with it the only reason to build a seven-seat vehicle.

The Ancestors and the Line This Vehicle Belongs To

Crew Safety, Escape and the Wider Problem

Comparison With Ground Prediction

The record holds one true comparison between a ground prediction and the flown system, and the two disagree. A vehicle-level load model, worked through under Sizing From First Principles, says that a canopy of 696.8 square metres could have been inflated in a single step inside three g at a deployment speed near twenty-seven metres per second. The flown system used five reefed stages. The discussion under Where the Framing Breaks Down explains why the conclusion drawn from that disagreement is an inference from a failure, and why its margin is a narrow twenty percent in deployment speed. No title in the survey reports this canopy’s inflation loads against which to set the flown ones.

The aerodynamic prediction began from an inherited shape. The X-24A shape had flown twenty-eight times between 1969 and 1971 [Martin Marietta X-24A], and the programme started from it instead of developing a new one [Wingless flight]. The enlarged shape was nevertheless measured again in wind tunnels at low speed and at hypersonic speed [Komerath, N. M. et al 1998] [Horvath, Thomas J. et al 2000], so the drop tests flew a shape whose ancestry was known from flight and whose own aerodynamics came from the tunnel. The article sets no drop-test aerodynamics beside those tunnel results.

The parafoil figures in this article are predictions with no flight value set beside them here. The sink rate of 5.56 metres per second, the airspeed of 17.58 metres per second and the energy ratio of 26.2 follow from a lift coefficient of 0.80 and a glide ratio of 3, which are typical values assumed for a large ram-air canopy. Aerodynamics from large-scale parafoil test programmes, one of them the X-38’s own, are reported in [Iacomini and Cerimele 1999] [Iacomini and Cerimele 1999] and [Madsen et al 2003], and the article does not take its coefficients from them. The table in The Flight Test Record that sets each drop-test mass beside a sink rate is computed from the same relation and is not a measured result. What flight established is the condition of the test and not the value of the coefficients. The heaviest drop test came within a factor of 1.021 of the orbital vehicle’s computed sink rate, so the landing system flew at very nearly its design condition.

The entry predictions have no flight counterpart at all. The deorbit increment of 132.8 metres per second, the ballistic peak of 3.87 g and the relieved peak of 3.02 g at a lift-to-drag ratio of 0.8 are calculations. No X-38 reached orbit, and the orbital vehicle V-201 was 90 percent complete when the programme was cancelled on 29 April 2002. For the half of the problem the vehicle was built to solve, flight returned nothing to compare, which the Epistemic State section records as the question the record does not settle.

What the Data Changed

What the Programme Settled

That a ram-air canopy of this size can be flown under control. A canopy of seven hundred square metres was the largest parafoil ever made [NASA X-38], and the programme flew it repeatedly, with staged reefing, autonomous guidance and a flare. It is a decelerator result and not a spacecraft result, and it stands independently.

That the guided-parafoil approach scales to a crewed vehicle’s mass. The heaviest drop test was within two percent of the orbital vehicle’s sink rate, so the landing system was demonstrated at condition.

What It Fed Into

The guided airdrop field took the work and kept going. Large steerable canopies for cargo delivery entered military service through the Joint Precision Airdrop System [Benney et al 2005] [Joshua and Eaton 2013], among them a 4,500 kilogram class guided system [George et al 2005], and the control and wind-estimation problems the X-38 solved for a crewed vehicle are the problems that field works on, as the cluster on guidance, homing and flare control of parafoils below shows.

The lifting body line continued without the parafoil. A commercial lifting-body spaceplane, Sierra Space’s Dream Chaser, is being developed to launch vertically and land on a conventional runway, the answer the X-38 declined to give. Its first flight, a free-flight demonstration that no longer visits the station, is scheduled no earlier than late 2026 [Dream Chaser].

What It Failed to Influence

No crewed vehicle in the record assembled here has since landed under a parafoil. The crewed capsules in the survey descend under round parachutes, the Soyuz under a braking parachute and then a main parachute [Soyuz spacecraft], and Shenzhou and Orion under parachute systems of the same kind [Jia et al 2014] [Lichodziejewski et al 2009]. The X-38’s specific answer, the gliding canopy for a crewed return, has no flown successor.

The Contemporary Literature

Cluster Records
Entry trajectories, guidance and control 338
Parachute aerodynamics, stability and descent 316
Parachute inflation, opening loads and reefing 288
Ram-air parafoils, their aerodynamics, inflation and flight dynamics 288
Lifting bodies and spaceplanes 250
Airdrop and aerial delivery systems 244
Guidance, homing and flare control of parafoils 230
Entry vehicle aerodynamics, aerothermodynamics and design 201
Landing impact attenuation, crashworthiness and touchdown 190
Parachute recovery of spacecraft, boosters and aircraft 166
Supersonic, planetary and inflatable decelerators 165
Spaceflight deconditioning and orthostatic intolerance 154
The X-38 and crew return vehicles 127
Crew safety, escape, abort and spaceflight risk 123
Parachute textiles, lines and structural testing 107
Thermal protection of entry vehicles 96
Human tolerance of acceleration and impact 95
The space station programme and the vehicles that serve it 86
Deorbit, landing opportunities and landing sites 25
Loads on the parachutist, opening shock and landing injury 24
The Apollo-Soyuz mission and the Soyuz record 21
Sizing, mass estimation and scaling 10
Total 3,544

The subjects below are the ones the article’s relations depend on. The analytic subsections read their modern form, and the cluster subsections after them hold every research record of the survey by subject, so that each record appears in exactly one cluster row.

Guided Parafoils Became an Industry While the Spacecraft Did Not

A large change since the X-38 is that autonomous guided parafoil delivery entered military service [Benney et al 2005] [Joshua and Eaton 2013]. The problems the programme solved for one crewed vehicle became working problems for cargo, and the modern literature on wind estimation, homing guidance, flare timing and touchdown accuracy is large and active, as the records below show.

Parafoil Aerodynamics and Flight Dynamics

Parafoil flight dynamics and the flow around a ram-air canopy are now simulated numerically [Tsuda and Yonemoto 2008] [Eslambolchi and Johari 2013], which this article reads as the largest methodological change in the field since the programme ran.

Inflation, Reefing and Opening Loads

The question this article could not answer from a vehicle-level model is the question this literature addresses. Modern inflation analysis simulates the inflating canopy numerically [Xia et al 2009] [Xu et al 2011], and a load distribution across the suspension lines computed that way could test the article’s inference about where the stage count comes from.

Parachute and Decelerator Systems

Landing Loads and Impact Attenuation

Human Tolerance, Deconditioning and the Medical Constraint

The entry load limit for this vehicle is a medical number and the medical literature has moved. What a deconditioned crew tolerates after months in free fall is better characterised now than it was [Pattarini et al 2020] [Glebova et al 2022], and it bears directly on the entry profile a lifeboat should fly.

Entry Trajectories and Guidance

Entry Aerothermodynamics

Thermal Protection in the Literature

Hypersonic and Configuration Aerodynamics

Crew Safety, Escape and Risk

Orbit, Deorbit and Landing Site Selection

The cluster on deorbit, landing opportunities and landing sites below holds the work on deorbit guidance, deorbit opportunities and landing site coverage.

The Station

The station’s programme, configuration, operations and serving vehicles are gathered in the cluster on the space station programme below, and its medical operations in the cluster on crew safety, escape, abort and spaceflight risk.

Vehicle Sizing and Scaling

Sizing and scaling are thin in this literature, as the count in Thin Subjects shows, and the records sit in the cluster on sizing, mass estimation and scaling below, with the scaling of canopy inflation in the clusters on parachute inflation and on ram-air parafoils.

The Vehicle and Its Ancestors, Reconsidered

Orthostatic Countermeasures and Occupant Injury, Recent Work

Entry trajectories, guidance and control

The entry the article computes but the vehicle never flew. Entry trajectories, analytic and numerical entry solutions, entry guidance and its bank-angle logic, the attitude control of entry vehicles, footprints and entry, descent and landing systems on Earth and Mars.

338 records. [Abilleira and Shidner 2012] [Adler 1998] [Agustin et al 1999] [Alexander 1978] [Amato 2021] [Anderson and Armitage 1993] [Arora 2002] [Aslanov 2017] [Aslanov 2017] [Atkins and Queen 2015] [Açıkmeşe et al 2014] [Bannova 2006] [Bao et al 2026] [Barth and Bailey 2007] [Bate and Johnson 1962] [Bell 1965] [Margolis et al 2021] [Bequaert and Chin 1963] [Bharadwaj et al 1998] [Blanchard and Desai 2011] [Blette and Braun 2016] [Bloomer and Rodriguez 2026] [Bojun et al 2019] [Bordano et al 1993] [Braun and Manning 2007] [Broglio 1961] [Brooks 1973] [Broome and Johnson 2007] [Brugarolas 2017] [Brugarolas 2021] [Brunner and Lu 2007] [Brunner and Lu 2010] [Bryson and Denham 1962] [Bump 1977] [Burkhart et al 2006] [Burkhart et al 2013] [Byrne 2020] [Calhoun and Queen 2006] [Canuto et al 2012] [Carson et al 2016] [Carter and Perlmutter 1965] [Causey and Sohoni 1973] [Cavallo and Ferrara 1996] [Cavallo et al 1996] [Chen et al 2014] [Cheng-Chih Chu] [Chern and Vinh 1978] [Christian et al 2007] [Clark et al 2021] [Coate and Lessing 1966] [Coate and Wingrove 1961] [Cohen 1965] [Cruz et al 2013] [Cui et al 2025] [D’souza et al 2014] [Danehy et al 2009] [Danesi 1982] [Engel et al] [Davis et al 2010] [de-Olive Ferreira et al 2000] [Dean et al 2025] [Dees 2015] [Desai and Lyons 2008] [Desai et al 1999] [Desai et al 2006] [Desai et al 2006] [Desai et al 2008] [Desai et al 2008] [Deyst 1968] [Dieriam 1990] [Divya and Jayashree 2023] [Owens] [Dow et al 1962] [Dryer 1960] [Dukeman and Fogle 2002] [Duncan 1968] [Dutta 2025] [Dutta and Braun 2014] [Dutta et al 2012] [Dutta et al 2014] [Dutta et al 2024] [Dutta et al 2025] [Dwyer Cianciolo and Powell 2017] [Elsey and Carlson 1968] [Engel et al 2024] [Evans and Dukeman 1995] [Evdokimov et al 2012] [Giraldo-Grueso et al 2025] [Fernandez et al 2014] [Ferri et al 2017] [Fine 1967] [Fink 1961] [Fisher et al 2006] [Foster 1960] [French and Howard 1971] [Fujino et al 2008] [Furfaro and Wibben 2012] [Garcia-Llama 2007] [Garcia-Llama 2010] [Garcia-Llama et al 2011] [Gebbie et al 2004] [Gnoffo et al 2016] [Goldman et al 1968] [Gracey et al 1981] [Grant et al 2010] [Grant et al 2010] [Grasso et al 2010] [Greene and Williamson 1982] [Grover et al 2008] [Guidance and navigation for 1968] [Hanson and Jones 2004] [Harpold 1980] [Harpold and Graves 1978] [Harpold and Hill 1980] [Harpold and Hill 1980] [Havill et al 1966] [Hayner et al 2025] [He et al 2017] [Heidrich and Braun 2017] [Hoelscher 2007] [Holloway 1967] [Hough 1982] [Hough 1982] [Hough 1982] [Hsu et al 1990] [Huang et al 2023] [Introduction Recent Developments in 2014] [Ishimoto 1995] [Ishimoto 2000] [Ivanov et al 2007] [Williams et al] [Jia et al 2018] [Johnson 2019] [Johnson et al 1982] [Johnson et al 2018] [Johnson et al 2019] [Johnson et al 2020] [Johnson et al 2020] [Johnson et al 2020] [Karlgaard et al 2023] [Kelley and Sullivan 1972] [Khan and Hoffman 2009] [Khan and Hoffman 2009] [Kipp et al 2007] [Knotts and Tamburro 1968] [Koelsch 2011] [Konstantinidis and Förstner 2020] [Kornreich 1963] [Korzun et al 2009] [Kropotin et al 2021] [Kumagai 1964] [Kumar Arora et al 2023] [Kyle 1976] [Kéchichian 2025] [Lafleur 2013] [Lafleur and Cerimele 2009] [Lee] [Lee 2006] [Lee and Cho 2002] [Lee and Cho 2006] [Lee and Lee 2023] [Lee et al 2004] [Lee 2011] [Lefland and Stehura 2022] [Leonardi 2023] [Leondes and Niemann 1966] [Lessing et al 1964] [Li 2017] [Li et al 2022] [Liang and Zhu 2021] [Liang et al 2018] [Liang et al 2020] [Lin et al 1984] [Lingard and Underwood 2014] [Lobbia 2017] [Love and Neustadt 1963] [Lu 1999] [Lu 2006] [Lu 2007] [Lu 2008] [Lu 2014] [Lu and Bayard 1997] [Lu and Shen 2003] [Lu and Xue 2009] [Lu et al 2000] [Lugo et al 2019] [Luo et al 2014] [Luo et al 2015] [McGrew et al 2026] [McGrew et al] [Maddock et al 2021] [Mall and Taheri 2022] [Mall et al 2024] [Marchetti et al 2024] [Margolis et al 2019] [Mease and Kremer 1992] [Mease et al 2002] [Mendeck and Craig 2011] [Mendeck and McGrew 2013] [Mendeck, Gavin F. 2011] [Mendeck, Gavin F. and McGrew, Lynn Craig 2012] [Wright et al] [Miller 1961] [Miller 1965] [Miller and Barton 2008] [Ming-Guang et al 2006] [Mischna 2024] [Miso et al 1999] [Miyazawa et al 1993] [Miyazawa et al 1999] [Moe 1960] [Mooij 2001] [Mooij 2004] [Mooij 2005] [Mooij 2017] [Mooij 2018] [Morth 1970] [Moshman and Proulx 2014] [MSL EDL Entry Guidance 2006] [Mulqueen and Coughlin 1991] [Mulqueen, J. A. 1991] [Nie et al 2017] [Ochi 2004] [Okolo et al 2020] [Palaszewski 2009] [Palaszewski 2012] [Palaszewski and Bencic 2011] [Palumbo et al 2017] [Peigin and Désidéri 2001] [Pejsa 1972] [Peng Lin and Jun Zhou 2010] [Percy et al 2018] [Petrov et al 1979] [Phillips and Cohen 1959] [Platus 1967] [Platus 1976] [Platus 1978] [Platus 1980] [Platus 1980] [Platus 1982] [Ploen et al 2009] [Polsgrove and Dwyer-Cianciolo 2016] [Powell et al 1976] [Greenhalgh et al] [Prince et al 2011] [Putnam and Braun 2014] [Putnam and Braun 2016] [Quadrelli et al 2009] [Queen et al 2011] [Lugo et al] [Lugo et al 2020] [Randall 1970] [Ray 2021] [Morth 1966] [Re-Entry Trajectory with Diveline 1993] [Rea and Putnam 2007] [Rea and Putnam 2007] [Ribarich 1967] [Ridderhof et al 2022] [Rodi 2021] [Roenneke 2001] [Roenneke and Cornwell 1993] [Ruger 1964] [Rui Teng et al 2016] [Sabin 1973] [Sagliano and Mooij 2018] [Samareh and Komar 2011] [San Martin et al 2013] [Santini De Leon et al 2020] [Sara Babu T 2014] [Schoenenberger et al 2014] [Schy and White 1968] [Seedhouse 2009] [Shen 1963] [Shen and Lu 2004] [Shen and Lu 2005] [Shurong et al 2017] [Skeen and Starkey 2014] [Smith 2016] [Sostaric et al 2011] [Spencer et al 1999] [Spratlin 1987] [Stalony-Dobrzanski 1966] [Steinfeldt and Tsiotras 2010] [Steinfeldt et al 2010] [Strahan and Sostaric 2016] [Striepe et al 2006] [Sun et al 2020] [Sunasawa and Ohta 1997] [Sushnigdha 2022] [Swaim 1966] [Swei 2014] [Tannas 1966] [Teofilatto 2024] [Terasaki 1963] [The Mars Science Laboratory 2014] [Tigges et al 2006] [Toigo et al 2003] [Tomlinson and Suit 1990] [Tribble et al 1994] [Tu and Yuan 2006] [Underwood and Bown 2001] [Vinh and Kuo 1997] [Vinh et al 1996] [Vitiello et al 2023] [Wallner and Well 2003] [Wang et al 2016] [Wang et al 2020] [Wang et al 2026] [Way 2011] [Way 2013] [Way et al 2006] [Way et al 2022] [Wei et al 2021] [White 1960] [Whitlock 1965] [Whitmore et al 2006] [Brandenburg et al] [Williams et al 2025] [Wingrove 1963] [Wong and Slye 1961] [Wu et al 2012] [Xie et al 2012] [Xie et al 2025] [Yamada 2022] [Yang and Meng 2012] [Yeh] [Yeo and Sng 1980] [Yoshino et al 2007] [Young, John W. 1961] [Zhang 2017] [Zhao and Pan 2025] [Zhao et al 2022] [Zhengchun 2018] [Zhou and Wang 1987] [Zhou et al 2012] [Zimmerman et al 2002] [zur Nieden and Olivier 2007]

Parachute aerodynamics, stability and descent

Round and cross canopies in steady descent. Parachute drag, wake, stability, cluster behaviour and descent dynamics. Parachute titles that name no inflation, recovery application, supersonic or planetary use, textile or gliding canopy are gathered here.

316 records. [Accorsi and Leonard 2002] [Acker 1983] [Aerodynamic Analysis of a Variable Damping Stabilized Parachute 2019] [Altgelt and Ward 1968] [Analysis of the Working 2016] [Androsenkov et al 2007] [Aquelet and Tutt 2007] [Aquelet and Tutt 2007] [Aquelet and Wang 2007] [Auerbach 1994] [Averyanov 2022] [Baksheev 1993] [Batemen 1920] [Behera et al 2023] [Behr 1989] [Behr 1999] [Bergeron et al 2011] [Bergeron et al 2023] [Bergeron et al 2025] [Birner et al 1993] [Black 1970] [Bleier et al 2015] [Bolton 1979] [Braisted 1989] [Braun 1953] [Braun and Walcott 1963] [Budolak et al 2022] [Buhler and Wailes 1973] [Calianno 1983] [Calianno 1986] [Calkins 1979] [Campbell 1968] [Cao and Jiang 2007] [Cao and Wei 2020] [Cao et al 2010] [Cao et al 2012] [Cassady, Leonard D. et al 2013] [Ch et al 2018] [Chandler 1967] [Lowry et al] [Charlotte et al 2021] [Christianson 1961] [Cochrane et al 2010] [Cockrell and Haidar 1993] [Cockrell et al 1986] [Councill and Goble 1970] [Councill and Goble 1971] [Craley and Desabrais 2007] [Cruz et al 2005] [Cuthbert 2010] [Daniel 2025] [Davydov and Mozgovoi 1998] [Dawoodian et al 2013] [Santis] [Santis 1973] [Defense Documentation Center Alexandria Va 1971] [Delurgio 1999] [Dennis 1983] [Dereng 1973] [Desabrais and Johari 2001] [Dinzl et al 2013] [Dormois et al 2025] [Downs and Bartlett 1989] [Doyle and Burbick 1974] [Eaton and Cockrell 1979] [Eiden and Foster 2023] [Ellsworth et al 1977] [Ray et al] [Fallon et al 1986] [Fan and Xia 2014] [Fatykhov 1993] [Fields and Yakimenko 2017] [Fields and Yakimenko 2017] [Fields et al 2011] [Fournier and Samuels 1967] [French 1971] [French 1984] [Fu and Koch 1977] [Gawron and Lopez 1997] [Giovangrossi et al 2026] [Gold 1984] [Goldberg 2025] [Gombos and Reed 1975] [Goulding et al 2011] [Grippon 2022] [Guglieri 2012] [Guruswamy 2015] [Guruswamy 2015] [Guruswamy 2017] [Guruswamy 2025] [Han and Trohanowsky 2001] [Heinrich et al 1961] [Heinrich and Rust 1965] [Heinrich et al 1965] [Hengel 1994] [Hennings et al 2005] [Henry et al 2017] [Herr 1989] [Herrington et al 2019] [Herrington et al 2019] [Heughan 1954] [Higuchi 1989] [Hogan 1992] [Hogue and Jex 1995] [Hogue et al 1992] [Hogue et al 1993] [Holan 2013] [Horinouchi et al 1964] [Hou et al 2023] [Huckins 1970] [Humi 1995] [Humi 2004] [Ibrahim, S. K. and Engdahl, R. A. 1974] [Il’chenko and Temnenko 1993] [Il’chenko and Temnenko 1994] [Izadi 2008] [Izadi and Dawoodian 2009] [Jackson 1954] [Jackson 1974] [Jailer et al 1960] [Jarman 2025] [Jiang et al 2023] [Jin et al 2014] [Jin et al 2016] [Johari and Desabrais 2005] [Johari and Levshin 2007] [Johari and Levshin 2009] [Johari et al 2000] [Johari et al 2001] [Jorgensen and Cockrell 1981] [Kalro and Tezduyar 2000] [Kenig et al 2015] [Kenig, Sivan J. et al 2013] [Kennedy and Lowry 1995] [Kim and Peskin 2009] [Kim et al 2013] [Klimas 1972] [Klimas 1973] [Klimas 1975] [Klimas et al 1983] [Knapik et al 2011] [Kolega et al 1986] [Kosaido et al 2026] [Kostelezky 2005] [Kostelezky and Schmitt 1999] [Kowaleczko grzegorz.kowaleczko@itwl.pl et al 2025] [Kumar and Udoew 2012] [Kunz and Kunz 1997] [Lai Thanh Tuan 2021] [Lampton 2010] [Ledyankina et al 2018] [Lee and Min 2016] [Levin and Shpund 1995] [Li 2015] [Li et al 2023] [Liu et al 2025] [Lobanov 1978] [Lobosky et al 2009] [Lonborg and Mack 1970] [Machin 2010] [Makarov et al 2016] [Maksimovic 1979] [Maru et al 2021] [Matsuo 1974] [McFALL and Murrow 1967] [McQuilling and Potvin 2011] [McQuilling and Potvin 2012] [McQuilling and Potvin 2012] [McQuilling et al 2011] [Menard 1967] [Mercan and İnalhan 2014] [Meyer 1986] [Meyerson 2001] [Mickelson et al 2006] [Minimum Performance Standard for] [Minimum Performance Standard for] [Minimum Performance Standards for] [Modern methods of parachute 2018] [Moog 1975] [Moore 2011] [Mort and Weiberg 1967] [Muller 1928] [Murray 1961] [Murri et al 2019] [Murrow and Preisser 1968] [Naidoo] [Niccum et al 1965] [Niederer 1966] [Niederer 1969] [Niederer 1972] [Niemi and Gowda 2013] [Niemi et al 2011] [Nock et al 2018] [Nykamp et al 2019] [Oler 1989] [Ozawa et al 2020] [Parate 2020] [Pedersen 1964] [Pei et al 2019] [Pei 2019] [Pepper 1967] [Pepper 1969] [Pepper 1985] [Pepper 1986] [Pepper and Collins 1981] [Pepper and Reed 1976] [Peterson and Johnson 1983] [Peterson et al 2024] [Pillasch et al 1984] [Platt et al 2006] [Ploskov 2020] [Pratap et al 2020] [Pratap et al 2021] [Prevorsek et al 1991] [Purvis 1983] [Purvis 1984] [Purvis 1984] [Purvis 1986] [Puthalapattu 2025] [Qiang et al 2012] [Ravnitzky 1989] [Ray and Machin 2015] [Robelen 1979] [Roberts 1979] [Roeger 1999] [Rong et al 2015] [Ross 1970] [Rybakiewicz and Plachá 2023] [Rychnovsky 1975] [Ryerson and Hauser 1989] [Rysev 1993] [Sahu et al 1997] [Janssen and Ray] [Sathe et al 2007] [Scale drogue parachute model 1974] [Schatzle and Curry 1980] [Scher and Draper 1950] [Scher and Gale 1948] [Schoenenberger et al 2005] [Schwalbe and Wagon 1997] [Seidman and Kamm 1943] [Shankar et al 2018] [Shen and Cockrell 1986] [Shigemoto et al 1982] [Shpund and Levin 1995] [Shpund and Levin 1997] [Silbert 1983] [Silbert et al 1989] [Spahr and Wolf 1981] [Speelman 1975] [Speelman 1977] [Steck et al 1967] [Stein 1991] [Stein et al 2000] [Stein et al 2001] [Stein et al 2003] [Stevens 1983] [Strickland and Higuchi 1995] [Strickland and Higuchi 1996] [Strickland and Macha 1989] [Strickland and Macha 1990] [Supercomputer Modeling of Parachute Flight Dynamics 2018] [Szczepaniak et al 2019] [Tadios 1991] [Takahashi and Higuchi 1988] [Takizawa and Tezduyar 2012] [Takizawa et al 2010] [Takizawa et al 2014] [Talay et al 1973] [Tang et al 2021] [Tanner et al 2013] [Teichroew 1954] [Tezduyar 2007] [Tezduyar and Osawa 2001] [Tezduyar and Osawa 2001] [Tezduyar et al 2001] [The net-skirt to a 1981] [Thomas et al 2007] [Toni 1968] [Usry 1969] [Utreja 1975] [Utreja 1975] [Utreja 1977] [Vardi] [Varela and Davidson 2026] [Vasile 2017] [Vasilo’chenko and Ponomarev 1985] [Vishniak 1993] [Walcott 1963] [Wang 2018] [Wang et al 2024] [Wang et al 2024] [Watson 1975] [Waye 1991] [Waye and Johnson 1989] [White 1968] [Whitlock 1973] [Whitmore et al 2004] [Wolf 1970] [Wolf and Spahr 1975] [Wolf and Spahr 1977] [Wu et al 2025] [Yakimenko and Jann 2015] [Yakimenko et al 2004] [Yang et al 2022] [Yavuz 1988] [Yavuz 1997] [Yavuz and Oler 1993] [Yue et al 2016] [Zhang 2003] [Zhang and Gao 2018] [Zhang and Gao 2019] [Zhang et al 2006] [Zhang et al 2013] [Zhang et al 2025] [Zhurin 2019]

Parachute inflation, opening loads and reefing

The decelerator chain the reefing argument reasons with. Canopy inflation, opening shock and opening force, snatch loads, added mass, reefing and disreefing.

288 records. [Comis and Machin 2019] [Pensado et al] [Pensado et al] [Parker et al] [An Experimental Study of Reefing Effect on Decelerating Parachutes 2002] [An experimental study on reefing effect on aerodynamics characteristics of cruciform parachute 2008] [An Experimental Study on the Inflation Characteristics of Parachute Canopies 2002] [Arai and Suzuki 2005] [As’ad et al 2025] [Asfour 1967] [Korzun et al] [Baginski et al 2013] [Barlog 1979] [Barton 1967] [Bassett et al 2017] [Behr et al 1999] [Bendura and Whitlock 1969] [Benney and Stein 1996] [Berndt and Deweese 1970] [Bohon and Miserentino 1970] [Bohon and Miserentino 1970] [Bozack and Doerr 1981] [Saulman and Wagner] [Brinkman 1992] [Brock et al 2017] [Cadieux and Barad 2025] [Cao and Xu 2004] [Cao et al 2009] [Cao et al 2017] [Cassady and Daum 2019] [Chen et al 2020] [Chen et al 2021] [Cheng et al 2012] [Cheng et al 2014] [Cheng et al 2016] [Karlgaard et al] [Clark et al 2009] [Cockrell 1991] [Coleman et al 2026] [Couch 1975] [Craig 1977] [Creel and Miserentino 1971] [Cruz et al 2003] [Cruz et al 2009] [Day 2013] [Desabrais and Johari 2001] [Desabrais and Johari 2003] [Dneprov and Ponomarev 1986] [Dneprov and Ponomarev 1991] [Doherr 1995] [Doherr 2003] [Du 2013] [Dutta et al 2020] [Elgabaili et al 2013] [Roelke and Green] [Fan and Steinhoff 2008] [Faurote 1971] [Fields 2016] [Fields and Basore 2015] [Fraire et al 2011] [Cadieux and Barad] [Fluid-Structure Interaction Simulations Of] [Cadieux and Barad] [Cadieux et al] [French 1963] [French 1964] [French 1967] [French 1968] [French 1969] [French 1969] [French 1971] [Gao et al 2013] [Gao et al 2015] [Gao et al 2016] [Gao et al 2016] [Gao et al 2020] [Garrard 1991] [Garrard and Konicke 1981] [Gerasimato 1991] [Gladh et al 2013] [Gladh et al 2017] [Greene 1970] [Grow and Preisser 1971] [Guan et al 2025] [Guo et al 2012] [Hancock and Lingard 2022] [Heinrich 1972] [Heinrich 1973] [Heinrich and Hektner 1970] [Heinrich and Jamison 1966] [Heinrich and Noreen 1970] [Heinrich and Saari 1975] [Heinrich and Saari 1978] [Heinrich and Saari 1978] [Heinrich et al 1974] [Herr 2009] [Horenstein and Roberts 1994] [Hou et al 2022] [Huang et al 2018] [Huang et al 2020] [Huckins 1970] [Huckins 1971] [Jamison 1967] [Potvin and Rangel 2026] [Jia et al 2013] [Jiang et al 2025] [Johari and Desabrais 2002] [Johari and Desabrais 2003] [Johari et al 2007] [DiNonno and Cheatwood] [Johnson 1971] [Boustani] [Boustani et al] [Jones and Klinar 1950] [Jorgensen 1991] [Junfang Zhou et al 2014] [Green et al] [Karlgaard et al 2018] [Kaspar and Grim 2025] [Keck 1975] [Khader and Huston 1987] [Kidane 2009] [Klimas 1979] [Klimas and Rogers 1977] [Konicke and Garrard 1981] [Kujawski 2003] [Kujawski and Stoychev 2005] [Kyser 1967] [Poole 1972] [Lee 1984] [Lee 1989] [Lee 1994] [Leonard et al 1999] [Li et al 2020] [Li et al 2024] [Li et al 2026] [Liang et al 2024] [Lingard 1995] [Lu et al 2025] [Ludtke 1973] [Ludtke 1973] [Ludtke 1982] [Ludtke 1986] [Ludtke 1988] [Ludtke 1991] [Macha 1993] [Mayhue et al 1970] [McBride and Henfling 2001] [McBride et al 1999] [McEwan, A. J. 1970] [McRonald 1995] [McVey and Wolf 1974] [Meacham et al 2013] [Melzig and Schmidt 1965] [Mikulas and Bohon 1969] [Miller 1968] [Miller 1975] [Miyoshi et al 2009] [Miyoshi et al 2009] [Mohaghegh and Jahannama 2007] [Montanez and Pantano 2026] [Morris et al 2011] [Guecha-Ahumada et al] [Natali et al 2013] [Nerem and Pake 1973] [Nie et al 2024] [Niemi 1991] [Niemi and Bevillard 2015] [Niemi 1992] [Ouyang and Zhang 2026] [Ouyang et al 2026] [Overend et al 2011] [Pantano and Montanez 2024] [Payne 1973] [Payne and Band 1976] [Payne and Band 1977] [Pepper and Cronin 1969] [Perschbacher and Potvin 1999] [Peterson 1996] [Peterson et al 2018] [Poole 1972] [Poole 1973] [Potvin 1999] [Potvin 2007] [Potvin 2007] [Potvin 2007] [Potvin 2007] [Potvin 2007] [Potvin 2022] [Potvin 2023] [Potvin and Patel 2009] [Potvin and Ray 2017] [Potvin and Ray 2019] [Potvin et al 2001] [Potvin et al 2007] [Purvis 1982] [Purvis 1984] [Qian et al 2012] [Rabinovitch et al 2022] [Ray 2013] [Ray, Eric S. 2013] [Ray 2013] [Reddy and Roberts 1975] [Redmond et al 1994] [Redmond et al 1995] [Research on Inflation Parameter Reconstruction and Dynamic Modeling Methods for Cluster Parachute Systems 2026] [Reza 2007] [Reza et al 2007] [Richardson et al 2005] [Roberts 1968] [Roberts 1974] [Roberts 1975] [Roberts 1979] [Roberts 1980] [Rodier 1979] [Deshmukh et al] [Deshmukh et al 2024] [Rooks et al 2020] [Ross 1972] [Sadeck and Lee 2009] [Sant and Allen 2011] [Sawyer 1972] [Hancock et al] [Hancock et al] [Sheta et al 2010] [Shi et al 2015] [Smollett 1955] [Sniezek 1992] [Hughes et al] [Hughes et al] [Strickland et al 2001] [Study on Critical Parachute Opening Speed Based on Air Resistance 2024] [Study on the Influence of Added Mass on Parachute Opening Load 2023] [Summary of Attached Inflatable 1968] [Sundberg 1975] [Talay and Poole 1971] [Tang and Qian 2015] [Tang and Qian 2016] [Tang et al 2015] [Tanner et al 2010] [Taylor and Murphy 2005] [Talay et al 1971] [Tian et al 2014] [Toni 1970] [Tutt and Taylor 2005] [Tynis et al 2019] [Vickery 1970] [Wang et al 2020] [Wang et al 2021] [Wang et al 2022] [Wang et al 2026] [Watkins 1995] [Watkins 2003] [Watts 1995] [Way 2018] [Webb 1986] [White 1974] [Whitmore and Hennings 2007] [Willis and Mikulas 1972] [Witkowski and Kandis 2010] [Witkowski et al 2009] [Wittendorfer and Wittendorfer 1997] [Wolf 1974] [Wolf 1989] [Wolf 1999] [Wolf and Croll 1981] [Wolf and Fallon 2011] [Wolf and Fallon 2011] [Xia et al 2009] [Xiaodong et al 2015] [Xing et al 2020] [Xu et al 2011] [Yan Jieyi et al 2010] [Yang et al 2015] [Yang et al 2017] [Yang et al 2020] [Yasumura and Kitamura 2021] [Yavuz and Cockrell 1981] [Ye et al 2026] [Yu and Ming 2007] [Yu et al 2014] [Yu et al 2025] [Zhang et al 2013] [Zhang et al 2024] [Zhang et al 2025] [Zhou et al 2014] [Zhu et al 2023] [Zou et al 2024]

Ram-air parafoils, their aerodynamics, inflation and flight dynamics

The keystone canopy. Ram-air parachutes, parafoils, paragliders and parawings, their aerodynamics, inflation, flight dynamics, system identification and test vehicles.

288 records. [Abdelqodus and Kursakov 2018] [Aerodynamic development of a 1976] [Alieksieiev et al 2022] [Altmann 2009] [Altmann 2015] [Altmann 2019] [Andreutti et al 2014] [Babinsky 1999] [Bair and Forehand 1968] [Balaji et al 2004] [Barrows 2002] [Barrows 2009] [Barton et al 1968] [Becnel and Frederick 2013] [Belloc 2015] [Belloc et al 2016] [Benedetti and de Freitas Pinto 2007] [Bennett and Fox 2005] [Bennett and Fox 2005] [Benolol and Zapirain 2005] [Berexa et al 2019] [Bergeron et al 2012] [Bergeron et al 2015] [Berland et al 2005] [Boffadossi and Savorgnan 2016] [Bowman] [Brown 1989] [Brown et al 2001] [Brückner et al 2005] [Buhler and Linhart 1969] [Carter and Rasmussen 2015] [Chae et al 2022] [Chambe et al 2024] [Charles 2017] [Charlotte et al 2026] [Chen et al 2026] [Clemmons 1967] [Clemmons 1970] [Clemmons 1971] [Croom 1971] [Croom et al 1964] [Croom et al 1965] [Cruz-Ayoroa et al 2014] [Cumelles Céspedes] [Cumelles Céspedes et al 2025] [Cumelles-Céspedes et al 2026] [Cumer et al 2012] [de Lange et al 2022] [Desabrais et al 2015] [Devalla et al 2015] [Devalla et al 2018] [Ding et al 2023] [Dogan et al 2026] [Dowling and Costello 2017] [Dowling and Costello 2018] [Drozd and Johnson 2001] [Dunker and Berland 2007] [Dunker et al 2015] [Eslambolchi and Johari 2013] [Faulders and Minott 1964] [Feng et al 2015] [Ferris and Kelly 1968] [Fields et al 2014] [Fogell et al 2017] [Fogell et al 2017] [Fralich 1965] [Francis M Rogallo 1962] [Furfaro et al 1997] [Gainer 1969] [Gainer and Sleeman 1968] [Gang 2015] [Gao et al 2020] [Geiger et al 1995] [Ghoreyshi et al 2014] [Ghoreyshi et al 2015] [Ghoreyshi et al 2016] [Ghoreyshi et al 2016] [Ghoreyshi et al 2016] [Ginsberg 1995] [Gloss 1969] [Gloss 1970] [Gonzalez 1993] [Goodrick 1970] [Goodrick 1975] [Goodrick 1979] [Goodrick 1981] [Gorman and Slegers 2012] [Guide on Wing Interface] [Gunasinghe et al 2017] [Guo et al 2017] [Güven and Şamiloğlu 2022] [Güven and Şamiloğlu 2022] [Hacker 1992] [Harada et al 2015] [Heinrich et al 1964] [Hintzke and Haggard 1991] [Hiraki 2003] [Hiraki and Hidaka 2013] [Hiraki et al 2005] [Hiraki et al 2007] [Hiraki et al 2015] [Hirst and Jorgensen 1995] [Hoisington 1999] [Hollestelle and Hollestelle 1997] [Hua et al 2013] [Hur and Valasek 2003] [Iacomini and Cerimele 1999] [Iacomini and Cerimele 1999] [Iacomini and Madsen 1999] [Ibos et al 1999] [Inoue et al 2004] [Ishida et al 2020] [Ivanov 2021] [Ivanov 2021] [Jaiswal et al 2020] [Jann 2001] [Jann 2003] [Jann and Strickert 2005] [Jann and Ward 2019] [Jann et al 1999] [Johnson and Sleeman 1963] [Kaesemeyer 2005] [Kaminer et al 2005] [Karimov and Shilov 2011] [Kelly and McNulty 1963] [Kemnitz 1991] [Kenner 1970] [Kim and Song 2015] [Kim et al 2008] [Kogler 1995] [Kolodny 2004] [Kulhánek 2019] [Kumar 2010] [Kumar et al 2017] [Kurashova and Vishnyak 1995] [Lee and Buckley 1999] [Levin 1968] [Li et al 2022] [Li et al 2023] [Li et al 2024] [Li et al 2024] [Libbey 1967] [Libbey et al 1967] [Lingard 2015] [Lissaman and Brown 1993] [Losilevskii 1995] [Lv et al 2019] [Madsen and Cerimele 2000] [Maekawa et al 2014] [Martin 1999] [Masahito Watanabe and Yoshimasa Ochi 2007] [Matos et al 1998] [Matsuo and Butler 1983] [Maślanka and Korycki 2020] [Maślanka and Korycki 2024] [Maślanka et al 2020] [Maślanka et al 2023] [McHatton and Morgan 1971] [Meyn and Bennett 1991] [Mingjun Li et al 2016] [Mkrtchyan and Johari 2011] [Mohammadi and Johari 2009] [Mohammadi and Johari 2010] [Montalvo and Costello 2016] [Montanez et al 1997] [Mooij et al 2003] [Morgan 1970] [Moriyoshi et al 2015] [Moriyoshi et al 2020] [Mort 1967] [Mortaloni et al 2003] [Mosseev 2001] [Mueller et al 2005] [Müller et al 2003] [Newberg et al 2026] [Nicolaides 1971] [Nicolaides 1976] [Nicolaides and Tragarz 1971] [Nie and Cao 2017] [Nie et al 2017] [Nielsen 1970] [Noetscher and Barber 2005] [Ochi 2020] [Ortega et al 2017] [Papadales 1971] [Patel et al 1997] [Pepper and Holt 1971] [Peralta and Johari 2015] [Perin and Patoux 2022] [Petry et al 1997] [Petry et al 1999] [Potvin 1995] [Potvin 1997] [Potvin 2001] [Potvin 2001] [Potvin and Peek 1998] [Potvin and Peek 2007] [Potvin and Potvin 1997] [Potvin et al 1997] [Potvin et al 2001] [Potvin et al 2007] [Prakash and Ananthkrishnan 2006] [Prakash et al 2005] [Prakash et al 2005] [Puskas 1984] [Puskas 1989] [Qiu et al 2025] [Redelinghuys 2007] [Redelinghuys and Rhodes 2007] [Redelinghuys et al 2015] [Seidel and Bergeron 2017] [Seidel et al 2016] [Shaw 2016] [Slegers 2017] [Slegers and Gorman 2011] [Smith and Ware 1967] [Smith et al 2001] [Specification for Continued Airworthiness] [Specification for Design and] [Specification for Manufacturer Quality] [Specification for Production Acceptance] [Specification for Required Product] [Standard Specification for Integration] [Streetman et al 2017] [Strickert 2004] [Strickert and Jann 1999] [Strickert and Witte 2001] [Summers 1970] [Szafran and Kramarski 2019] [Takizawa et al 2016] [Tang et al 2026] [Tanigawa and Hiraki 2012] [Tao et al 2016] [Tao et al 2018] [Tezduyar 1998] [Tezduyar et al 1997] [Toni and McNulty 1965] [Toussaint et al 2013] [Townend 1970] [Traub and Okayama 2018] [Tribot et al 1997] [Tsuda and Yonemoto 2008] [Shved 2025] [Velasquez and Benedict 2015] [Wailes 1993] [Wailes and Harrington 1995] [Wang and Yang 2024] [Wang et al 2025] [Wang et al 2026] [Ward et al 2012] [Ward et al 2012] [Ward et al 2024] [Ware 1969] [Watanabe and Ochi 2008] [Watanabe and Ochi 2008] [Wegereef and Jentink 2003] [Wegereef and Jentink 2005] [Wegereef et al 2009] [Wegereef et al 2011] [Wilkes et al 2021] [Wilkes et al 2021] [Wise 2006] [Wu et al 2017] [Wu et al 2018] [Wyllie et al 1997] [Xu et al 2025] [Yakimenko 2005] [Yakimenko and Statnikov 2005] [Yan et al 2025] [Yanaga et al 2014] [Yang et al 2017] [Yu et al 2026] [Zeng et al 2026] [Zeng et al 2026] [Zhang et al 2018] [Zhang et al 2021] [Zhang et al 2022] [Zhang et al 2025] [Zhang et al 2026] [Zhang et al 2026] [Zhang et al 2027] [Zhao et al 2022] [Zhu et al 2001] [Zhu et al 2014] [Zhu et al 2021] [Zhu et al 2022] [Zhu et al 2023] [Zhu et al 2023]

Lifting bodies and spaceplanes

The line the X-38 belongs to. The M2, HL-10, X-24, HL-20 and Dream Chaser lifting bodies, the Hermes and other spaceplanes, the Shuttle orbiter and reusable launch vehicles in entry.

250 records. [Adams et al 1973] [Al Fatih et al 2021] [Allen 2024] [Almosnino 2016] [Anderson et al 1963] [Antonenko and Ebeling 1989] [Aprovitola et al 2019] [Aradag et al 2007] [Argyris et al 1989] [Aso et al 2004] [Badarudin Mohamad Badry et al 2013] [Baiocco et al 2007] [Banks and Fisher 2006] [Barret, Chris 1998] [Barret, Chris 1999] [Baumgartner and Elvin 1995] [Beam 1991] [Bendor et al 1960] [Benson 2006] [Benson et al 1993] [Bentley 2009] [Bentley 2009] [Bentley 2009] [Berkes 1992] [Betin 1991] [Bomer and Tulet 1990] [Borden, David et al 1999] [Bouslog, S. et al 1998] [Boylan and Potter 1966] [Brumley and Perich 2022] [Brunner et al 1966] [Bryson et al 1968] [Buffo 1990] [Bush et al 1993] [Bush et al 1993] [Chaudhary et al 2001] [Chavagnac et al 2013] [Chelotti et al 1992] [Chen et al 2026] [Chin 1970] [Collins et al 1970] [Colvin 2021] [Coue 2003] [Cruz and Bell 1995] [Cruz and Ware 1992] [Cruz and Ware 1995] [Cruz et al 1989] [Dana et al 1969] [De Angelis and Tang 1969] [Deng et al 2017] [Deng et al 2024] [Design features of lifting 2013] [Desikan and Srinivasan 2018] [Direct numerical simulations of hypersonic boundary layer transition over a hypersonic transition research vehicle model lifting body at different angles of attack 2023] [Driver and Vess 1991] [Duffy et al 1993] [Dufour et al 2014] [Dumbacher 2003] [Eliseev et al 2014] [Erwin 1990] [Exum 1991] [Falarski and Mort 1969] [Falarski, M. D. and Mort, K. W. 1970] [Feustel-Büechl 1988] [Freeman 1992] [Fuhrmann 2003] [Gao et al 2012] [Layton 1970] [Gentry 1972] [Gentry et al 1966] [Griffin and Takahashi 2022] [Grigoli 2024] [Hanson and Jones 2003] [Hassell 1960] [Herholz and Valentiny 1988] [HL-20 Personnel Launch System 1990] [Holmes 1970] [Holt et al 2016] [Hossan and Srinivas 2023] [Ingvarson et al] [Jackson and Cruz 1992] [Jackson et al 1991] [Jackson et al 1992] [Jackson et al 1993] [Jackson, E. B. et al 1991] [Stevens et al 1966] [Jekosch 1991] [Jenkins et al 1968] [Jeong et al 2009] [Jernell, L. S. 1971] [John A Manke et al 1970] [McTigue 1970] [Pyle and Ash 1970] [Jouhaud 1992] [Kaminsky and Johnson 1964] [Katz et al 1998] [Kawato et al 2005] [Kazi et al 2019] [Kempel 1971] [Kempel and Painter 1993] [Kempel et al 1994] [Kempel, R. W. and Manke, J. A. 1974] [Kempel, R. W. et al 1975] [Khurana et al 2012] [Klevatt and Gaubatz 1998] [Koch et al 2025] [Kock and Painter 1968] [Kock and Painter 1969] [Kotfila and Painter 1969] [Lagimoniere and Avram 2024] [Larsen et al 2025] [Larsen et al 2025] [Larson, R. R. 1972] [Lauer 2006] [Launius 2013] [Layton, G. P., Jr. and McTigue, J. G. 1969] [Lemaignen et al 1986] [Lu 1996] [Lu 1997] [Lu 1999] [Lu 1999] [Maddock and Minisci 2016] [McCown 1967] [McNamara 1971] [McTigue and Ryan 1968] [Merlin 2014] [Meyer-Allyn et al 2012] [Miller, C. G. 2000] [Tang 1970] [Morio et al 2009] [Morris 1993] [Morris et al 1993] [Mu and Zhang 2014] [Nebylov and Tomita] [Nebylov et al 1999] [Neuhaus 2018] [Nietubicz 1975] [Ohkami et al 1991] [P.V and Laxman 2023] [Page and Anderson 1996] [Painter, W. D. and Sitterle, G. J. 1974] [Palmer et al 1994] [Palmer et al 1995] [Penland, J. A. 1975] [Penn and Lindley] [Penn and Lindley 1997] [Powell 1993] [Powell and Cruz 1991] [Putnam et al 2013] [Putnam et al 2014] [Pyle 1971] [Qi et al 2021] [Qian et al 2012] [Reed et al 1997] [Raillon et al 1992] [Rana et al 2017] [Rasmussen 1978] [Rasmussen 1979] [Reaser 1997] [Redding 1984] [Reimann 2016] [Rivers et al 1991] [Rivers et al 1994] [Rizvi et al 2013] [Kempel et al 1970] [Rodiere et al 1988] [Ruf et al 1996] [Saccani 2020] [Sager 1995] [Saltzman et al 1999] [Saltzman et al 2002] [Scallion 1999] [Shawyer 2023] [Sim, A. G. 1973] [Skoog 1987] [Smith] [Smith 1965] [Smith et al 1998] [Snapp and Rodriguez 2011] [Soistmann and Spain 1993] [Spaceplane Coordinates 2016] [Spaceplane History 2002] [Spaceplane Low-Cost Potential 2002] [Stapleton et al 1997] [Stillwagen 1999] [Stone and Macconochie 1993] [Stone and Piland 1991] [Stone and Piland 1993] [Stone and Powell 1976] [Strutz, L. W. 1972] [Su and Liu 2025] [Su and Liu 2025] [Su et al 2021] [Su et al 2021] [Surber and Olsen 1978] [Suzuki et al 1997] [Talay 1992] [Talay 1992] [Talay, Theodore A. and Stone, Howard W. 1991] [Tang and Pearson 1971] [Tang, M. H. and Pearson, G. P. E. 1973] [Tartabini et al 2002] [Taylor and Allison 2015] [Taylor and Howard 2008] [Temple 2006] [Tendero Ventanas] [The Spaceplane Space AGE 2002] [Thompson 1966] [Thompson 1970] [Thompson 1970] [Tian et al 2015] [Tile-Gap Flow in the 1983] [Trifoni and Lafferty 2025] [Vaganov et al 2009] [van den Abeelen 2017] [van Oort et al 2007] [Vannier] [Vetter 1966] [Viladegut 2018] [Viviani et al 2020] [Vos and Farokhi 2015] [Walyus and Dalton 1991] [Ware and Cruz 1993] [Ware and Cruz 1993] [Ware et al 1991] [Wartemann et al 2018] [Webb and Bettinger 2024] [Weilmuenster and Greene 1993] [Wierzbanowski and Ramasubramanian 2020] [William H Dana and J R Gentry 1970] [Willshire et al 1993] [Winnick 1996] [Woffinden et al 2011] [Wu 1984] [Wu et al 2020] [Wurster and Stone 1993] [Wurster et al 1999] [XCOR, Developing the Next 2016] [Yamada and Suzuki 2016] [Young and Underwood 1983] [Youssef et al 2001] [Yuta Akai et al 2007] [Zarrouati et al 1988] [Zea et al 2012] [Zhang et al 2026] [Zhu et al 2002] [Zou et al 2015] [Zou et al 2025] [Zuppardi and Mongelluzzo 2023] [Zuppardi and Mongelluzzo 2023]

Airdrop and aerial delivery systems

The field the X-38’s parafoil came from and returned to. Cargo and personnel airdrop, precision and guided airdrop systems, platforms, extraction and cushioning.

244 records. [Accorsi et al 2001] [Adrian 2024] [Aggarwal and Kumar 2019] [Aguilar and Figueiredo 1995] [Alexander et al 2007] [Alshahin et al 2015] [Bagdonovich et al 2003] [Baker et al 1968] [Barnard et al 1975] [Beaubien 1997] [Behr 1993] [Bennett and Bennett 1997] [Benney et al 2005] [Benney et al 2005] [Benney et al 2009] [Bergeron et al 2011] [Bergeron et al 2013] [Bergeron et al 2018] [Bergeron et al 2019] [Bergeron et al 2020] [Berlind 2001] [Beyer and Costello 2007] [Bishop et al 2008] [Black 1980] [Blake 1996] [Blake and Blake 1997] [Bledsoe and Bernatovich 2015] [Bonaceto and Schroeder 1984] [Brown et al 1999] [Burdette et al 2017] [Cacan and Costello 2017] [Cacan and Costello 2018] [Cacan et al 2015] [Cacan et al 2015] [Cacan et al 2015] [Cacan et al 2016] [Cacan et al 2019] [Cambell et al 2005] [Chakoian 1969] [Chakoian and Michal 1968] [Chang and Ripperger 1969] [Charles 2007] [Charles 2015] [Chen and Shi 2011] [Chen and Zhang 2012] [Cheng et al 2023] [Cinnamon et al 2017] [Cinnamon et al 2017] [Civelek and Genc 2026] [Costello et al 2017] [Cui et al 2025] [Cui et al 2026] [Cuthbert and Desabrais 2003] [Dale and Ludwig 1968] [Dellicker et al 2000] [Desabrais 2004] [Desabrais 2005] [Deshpande et al 2024] [Dever et al 2017] [Dooley et al 2002] [Dyatt 2005] [Evans 2019] [Evans et al 2019] [Evans 2019] [Farinacci and Bruner 1973] [Farrell 2011] [Fox et al 2001] [Fraire 2017] [Fraire 2019] [Fraire 2022] [Fraire 2024] [Fraire 2024] [Fraire and Desabrais 2026] [Fraire and Tokatli 2022] [Fraire et al 2019] [Fraire et al 2026] [French 1966] [Fritzler 1973] [Galkin et al 2022] [Gao et al 2016] [Gao et al 2017] [Geisbauer and Schmidt 2015] [Geiselman et al 2015] [George et al 2005] [Gerlach and Doman 2016] [Gerlach and Doman 2016] [Gerlach et al 2016] [Gerlach et al 2017] [Ghoreyshi et al 2020] [Giebutowski 1975] [Gilles et al 2005] [Gionfriddo 1966] [Gionfriddo 1967] [Gionfriddo 1989] [Guang-zhi and Xiu-xia 2014] [Guo et al 2025] [Guo et al 2026] [Haller et al 2017] [Han 2018] [Han 2025] [Han et al 2015] [Hannah and Ronsick 1988] [Hattis et al 1997] [Hattis et al 2000] [Hattis et al 2003] [Hattis et al 2006] [He et al 2013] [Henry 2015] [Herrmann et al 2012] [Herrmann et al 2013] [Hershman 2005] [Hester 1970] [Hu and Yao 2012] [Hunter 1973] [Hunter and Wuest 1989] [Ireland 2006] [Ivanovic and Orsag 2022] [Jan and Ripperger 1969] [Jann 2011] [Jann 2015] [Jann and Geisbauer 2013] [Jiang et al 2026] [Johari and Desabrais 2005] [Johnson et al 2001] [Jorgensen and Hickey 2005] [Joshua and Eaton 2013] [Jóźwiak and Kurzawiński 2019] [Ke et al 2006] [Kelly and Pena 2001] [Klein and Rogers 2015] [Klinkmueller et al 2019] [Kostrubala 2011] [Kunz 1995] [Kunz 1995] [Kurz 1964] [Kushleyev et al 2011] [Le Garrec et al 2022] [Lee et al 2019] [Leon et al 2019] [Leon et al 2022] [Leonard et al 2019] [Leonard et al 2020] [Lewis 1964] [Li and Huang 2012] [Li et al 2017] [Li et al 2021] [Li et al 2021] [Lis and Tavernetti 1999] [Liu 2012] [Liu et al 2013] [Liu et al 2015] [Liu et al 2016] [Lopez and Wuest 1995] [Lozar 2009] [Machin and Evans 2013] [Mao et al 2018] [Mathisen et al 2020] [Maxwell et al 2023] [McCann et al 2019] [McClung et al 1975] [McGrath et al 2005] [McHugh et al 2005] [McQuilling et al 2010] [Michal et al 1970] [Mingaleev et al 2020] [Moog et al 1979] [Morton et al 2006] [Noetscher et al 2021] [Pepper et al 1984] [Petry 1975] [Phipps 1954] [Ploskov 2021] [Pm et al 2024] [Poole et al 1994] [Potvin 2001] [Pramod et al 2021] [Precision Aerial Delivery Systems 2015] [Pu 2015] [Qu et al 2011] [Raissi et al 2008] [Ray and Varela 2015] [Sadeck et al 2009] [Janssen and Varela 2026] [Scheirey et al 2026] [Scheuermann et al 2017] [Schnepf and Richter 2024] [Seeger et al 2005] [Sego 2001] [Slayman et al 1970] [Steeves 1982] [Strong et al 2005] [Sun et al 2024] [Sun et al 2026] [Sun et al 2026] [Sun et al 2026] [Tardiff and Woodruff 2009] [Tardiff et al 2015] [Tavan et al 2009] [Tiaden 2017] [Vambol et al 2023] [Wachlin and Costello 2019] [Wachlin et al 2019] [Wachlin et al 2022] [Wang 2026] [Wang and Yang 2023] [Wang et al 2013] [Wang et al 2016] [Wang et al 2024] [Wang et al 2025] [Wang et al 2026] [Ward and Costello 2012] [Ward et al 2009] [Ward et al 2010] [Ward et al 2010] [Ward et al 2011] [Ward et al 2015] [Ward et al 2015] [Ward et al 2019] [Warrick and Lee 2001] [Warrick et al 2003] [Watkins et al 2017] [Webber 2003] [Wegereef and Jentink 2007] [Wenqian et al 2016] [Witham 2007] [Wright et al 2005] [Wu and Yang 2022] [Xu and Yu 2024] [Xu et al 2026] [Xu et al 2026] [Yajie Dou et al 2013] [Yakimenko et al 2002] [Yakimenko et al 2009] [Yang and Jeon 2019] [Yang and Ke 2007] [Yang et al 2023] [Yerdon 1999] [Zarbock 2025] [Zhang 2024] [Zhang et al 2023] [Zhang et al 2025] [Zhou et al 2003] [Zhou et al 2025] [Zou et al 2025]

Guidance, homing and flare control of parafoils

The autonomous descent. Homing, trajectory planning, path following, wind estimation, flare and landing control of parafoils and powered parafoils.

230 records. [Anglin 1962] [Balraj Gupta et al 2023] [Benton and Yakimenko 2013] [Binz et al 2017] [Boisseau and Chambers 1966] [Brown 1993] [Bugg and Sleeman 1967] [Bettanini et al 2020] [Cacan et al 2015] [Cacan et al 2017] [Calise and Preston 2006] [Calise and Preston 2008] [Cao et al 2026] [Carter et al 2007] [Chambers 1966] [Chen et al 2017] [Chen et al 2019] [Chen et al 2021] [Chen et al 2021] [Chen et al 2021] [Chen et al 2025] [Chen et al 2025] [Chen et al 2026] [Chiel 2015] [Chiel and Dever 2015] [Chiel and Dever 2015] [Chin et al 2016] [Civelek and Kıvrak 2024] [Cui et al 2025] [Cui et al 2025] [Cui et al 2026] [Devalla and Prakash 2015] [Devalla et al 2015] [Devalla et al 2016] [Doherr et al 1997] [Doran et al 2025] [Duan et al 2026] [Feng et al 2025] [Formal’skii and Zaitsev 2013] [Fowler and Rogers 2013] [Fowler and Rogers 2014] [Gao and Tao 2022] [Gao et al 2016] [Gao et al 2019] [Gavrilovski et al 2011] [Gavrilovski et al 2012] [Gimadieva 2001] [Gockel and Gockel 1997] [Goodrick 1969] [Goodrick 1979] [Gorman and Slegers 2011] [Guo and Wu 2026] [Guo et al 2020] [Guo et al 2021] [Guo et al 2022] [Guo et al 2023] [Guo et al 2023] [Guo et al 2023] [Handley et al 2017] [He et al 2022] [He et al 2024] [Hewes 1961] [Hiraki and Inoue 2009] [Hiraki et al 2004] [Huba et al 2011] [Ishitsu et al 2011] [Jann 2005] [Jaquet et al 1969] [Jie et al 2026] [Jin et al 2015] [Jin et al 2025] [Jin et al 2026] [Jin Tao et al 2016] [Johnson 1963] [Kondo et al 2009] [Kumar et al 2020] [Lashbrook and Mabry 1968] [Le Moing et al 2022] [Lee and Arena 2014] [Lee and Buckley 2000] [Lee et al 2014] [Lee et al 2015] [Lee et al 2016] [Leeman et al 2022] [Li and Lin 1991] [Li and Nan 2023] [Li and Yan 2021] [Li et al 2016] [Li et al 2016] [Li et al 2016] [Li et al 2016] [Li et al 2018] [Li et al 2020] [Li et al 2020] [Li et al 2025] [Li et al 2025] [Li et al 2026] [Limin et al 2019] [Linhart and Moeller 1970] [Liu and Ran 2023] [Liu and Wu 2019] [Long et al 2021] [Lu et al 2023] [Luan et al 2026] [Lucrezia 2023] [Lund 2004] [Luo et al 2016] [Luo et al 2018] [Luo et al 2019] [Lv et al 2020] [Ma et al 2022] [Ma et al 2023] [Machin et al 1999] [Masuda and Yonemoto 2009] [Matthies et al 2019] [Moreno et al 2024] [Murali et al 2013] [Murali et al 2014] [Murray, James E. et al 1994] [Naeseth 1970] [Nakajima et al 1995] [Nakasuka et al 2004] [Ochi 2013] [Ochi et al 2009] [Ogawa et al 2012] [Olenberger 1978] [Park and Bang 2024] [Park et al 2022] [Pearson et al 1977] [Penev 1997] [Pepper and Biesterveld 1973] [Peyada et al 2007] [Pollini et al 2002] [Prakash 2020] [Prateek Sazawal and Ghosh 2023] [Qi et al 2025] [Qu 2019] [Rademacher] [Rademacher] [Rademacher et al 2008] [Rakesh and Harikumar 2019] [Rogallo and Sleeman 1967] [Rogers and Slegers 2013] [Sahbon et al 2026] [Shao et al 2024] [Sibilski et al 2008] [Sivera et al 2021] [Slegers and Costello 2003] [Slegers and Costello 2003] [Slegers and Costello 2003] [Slegers and Costello 2005] [Slegers et al 2015] [Soppa et al 1997] [Suit et al 1964] [Sun et al 2018] [Sun et al 2020] [Sun et al 2020] [Sun et al 2020] [Sun et al 2021] [Sun et al 2022] [Sun et al 2022] [Surendra et al 2015] [Suresh Babu et al 2014] [Takahashi et al 2025] [Tan et al 2017] [Tan et al 2019] [Tan et al 2023] [Tanaka et al 2019] [Tao et al 2016] [Tao et al 2016] [Tao et al 2016] [Tao et al 2017] [Tao et al 2017] [Tao et al 2019] [Toglia et al 2010] [Wang et al 2022] [Wang et al 2024] [Ward and Costello 2013] [Ward et al 2010] [Ward et al 2011] [Ward et al 2012] [Ward et al 2013] [Ward et al 2022] [Ward et al 2024] [Wei and Pearson 1974] [Wei and Shao 2024] [Wei et al 2024] [Wei et al 2024] [Wei et al 2026] [Weinstein et al 2018] [Wu et al 2018] [Xing et al 2023] [Xing et al 2024] [Yakimenko and Fields 2015] [Yan et al 2023] [Yan et al 2026] [Yang et al 2014] [Yang et al 2016] [Yang et al 2025] [Yang et al 2025] [Yang et al 2026] [Yao et al 2018] [Yi et al 2025] [Yu et al 2022] [Yu et al 2025] [Yu et al 2025] [Yu et al 2026] [Yu et al 2026] [Zaitsev and Formal’skii 2008] [Zhang et al 2012] [Zhang et al 2016] [Zhang et al 2022] [Zhang et al 2024] [Zhang et al 2026] [Zhao and Jianyi 2009] [Zhao et al 2020] [Zhao et al 2021] [Zheng et al 2022] [Zheng et al 2023] [Zheng et al 2023] [Zheng et al 2024] [Zhigang Xie et al 2011] [Zhou et al 2026] [Zhu and Shi 2025] [Zhu et al 2021] [Zhu et al 2022] [Zhu et al 2023] [Zhu et al 2023] [Zi-li and Hao 2016] [Zou et al 2018]

The guidance literature is mostly recent. Of its dated records, 39 date from 2006 or earlier, 64 from 2007 to 2016 and 125 from 2017 onward, so the work on homing and flare control that the X-38 needed for one vehicle has grown since the programme stopped.

Entry vehicle aerodynamics, aerothermodynamics and design

The vehicles built to survive entry, described as bodies. Entry vehicle aerodynamics, heating, plasma and communications blackout, and entry vehicle concepts and design.

201 records. [Brandis et al] [Akin 2010] [Andrienko et al 2016] [Aprovitola et al 2021] [Argyris et al 1990] [Arho 1971] [Atkinson et al 2013] [Atmospheric Entry 2004] [Balakrishnan and Kurian 2014] [Barnhardt and Candler 2012] [Barnhardt et al 2019] [Barnhardt et al 2019] [Barzda 1967] [Berger 2009] [Bilimoria and Mueller 2010] [Brauckmann 1986] [Bryson et al 1962] [Büchner et al 1997] [Campbell and Brown 1973] [Candler 2001] [Casani 1968] [Cassanto 1966] [Chang, Chau-Lyan et al 2009] [Cinquegrana 2015] [Claeys et al 2022] [Cobleigh et al 1999] [Kazemba et al] [Couch and Morris 1968] [Cruden 2024] [Curry et al 1968] [Dana 1968] [Di Clemente et al 2009] [DiFranco 1971] [Divitiis and Vitale 2010] [Dix et al 1967] [Djamshidpour] [Dobies 1957] [Draper and Buck 1968] [Dunn and Nickell 1971] [East 2010] [Eggers and Swenson 1966] [Evans et al 1970] [Fannelop 1968] [Fante et al 1970] [Faulders et al 1968] [Finke 1990] [Fong et al 1970] [Frankenthal 1964] [French 1981] [Ghorai 1968] [Glaab et al 2013] [Golden 1969] [Gong et al 1984] [Hall and Nowlan 1978] [Hankey and Hooks 1963] [Hashimoto et al 2016] [Helms 1973] [Holleman and Adkins 1964] [Hollis 2012] [Hollis 2010] [Hooks and Hankey 1965] [Horstman and Kussoy 1967] [Hosder and Bettis 2012] [Neumann et al] [Rea et al] [Jiji 1967] [Johnson et al 2017] [Joint Conference on Lifting 1960] [Jorgensen 1965] [Joseph et al 2026] [Kachadourian 1970] [Kanda et al 2006] [Karl et al 2015] [Katsurayama et al 2008] [Kaufman 1970] [Kaufman and Louis G. 1964] [Kaufman and Louis G. 1964] [Kaushikh et al 2018] [Keidar et al 2008] [Kellas 2017] [Kennedy and Fields 1962] [Khavanov et al 2020] [Kim et al 2008] [Kim et al 2010] [Kimmel et al 2011] [Ko, William L. et al 2007] [Koga et al 2014] [Lau 2008] [Lennon and Poirter 1974] [Levensteins and Krumins 1967] [Levin and Smith 1968] [Levinsky 1962] [Li 1989] [Li et al 2013] [Lin 2008] [Liu et al 2010] [Logan 1968] [Halstrom et al] [Halstrom et al] [Loh 1962] [Lusty and Miele 1966] [Lykoudis 1964] [Lynch 1966] [Lynch 1968] [Mandell 1962] [Marwege and Gülhan 2023] [Masaki and Yakura 1969] [Mascy et al 1988] [Mazaheri 2013] [Meginnis et al 2012] [Mehta 2006] [Menard 1968] [Barnhardt et al] [Barnhardt et al] [Mitcheltree et al 2000] [Moss et al 2006] [Mungiguerra et al 2017] [Nachtsheim and Lehman 1980] [Nagata et al 2026] [Nance 2013] [Nelson and Coward 1968] [Nicolet et al 1982] [Nomura et al 2018] [Nomura et al 2019] [Olynick 1996] [Otey and English 1977] [Paine 1967] [Paolozzi 2004] [Park 1976] [Park et al 2024] [Pavlov and Simakova 2021] [Peigin and Postnikov 1987] [Perez] [Perez-Rivera 2026] [Perminov 1969] [Pettus 1970] [Pezzella 2015] [Pezzella and Trifoni 2015] [Jarvinen et al 1968] [Plumb 1971] [Price and Ericsson 1970] [Radiation and Reentry 1968] [Re-Entry and Vehicle Design 1960] [Rea 2008] [Reda 2001] [Reddy and Sinha 2009] [Rehder 1973] [Ri et al 2026] [Rossman et al 2017] [Saltzman, Edwin J. et al 2007] [Sanchez-Muñoz et al 2024] [Santos et al 2026] [Sasoh and Fujiwara 1990] [Savage and Tinling 1959] [Savino et al 2015] [Schadt 1968] [Schermerhorn and Demeritte 1960] [Schmitt 1972] [Seiff 1964] [Sforza 2021] [Shang and Surzhikov 2011] [Shao et al 2016] [Sharenson 1966] [Sheldon 1967] [Shimosawa and Fujino 2016] [Simons 1975] [Spearman 1984] [Spencer, B., Jr. 1971] [Spencer, B., Jr. and Fournier, R. H. 1973] [Spiegel et al 1968] [Spravka and Jorris 2015] [Starkey 2015] [Surzhikov 2010] [Swenson et al 2025] [Takahashi et al 2015] [Takahashi et al 2016] [Takahashi et al 2019] [Takizawa et al 2004] [Tamma and Thornton 1984] [Tauber 1968] [Teichman and Hirsch 2014] [Thomas and Perlbachs 1967] [Tigges et al 2011] [Tong 1991] [Townend 1979] [Vicente 1964] [Viviani and Pezzella 2010] [Wang et al 2021] [West and Hosder 2015] [West et al 2014] [Wilcox 1974] [Winter et al 2019] [Witzeman 2003] [Wong, Thomas J. et al 1960] [Wright 2018] [Xerikos and Anderson 1962] [Yaroshevskii 2006] [Young et al 1972] [Zhao 1993] [Zhong and Levin 2010] [Zuppardi et al 2016]

Landing impact attenuation, crashworthiness and touchdown

The stroke the touchdown argument relies on. Landing impact attenuation, airbags, crushable and energy-absorbing structure, landing gear and skids, seats and occupant protection, and touchdown loads.

190 records. [3D-Printed Collision Energy Absorber] [Ali] [Armstrong 1964] [Cianciolo and Welch] [Allen et al 1962] [Allen et al 1963] [Altin et al 2017] [Arık and Bilgiç 2022] [Bakulin et al 2016] [Baykasoğlu et al 2023] [Benson et al 1964] [Bhutada and Goel 2021] [Bie et al 2026] [Black 1964] [Bown and Darley 2005] [Bronstein et al 2015] [Budd Co Fort Washington Pa Technical Center 1978] [Cadogan et al 2002] [Calhoun and Queen 2002] [Carper and Burrows 1988] [Castrichini et al 2017] [Cheatham and Hackler 1966] [Chen et al 2024] [Chester 2002] [Cho et al 2025] [Chong and Dix 2004] [Cloutier 1966] [Cloutier 1966] [Cloutier 1967] [Crist and Symes 1981] [Jones et al] [Darley et al 2013] [Daum and Gay 2013] [Davies 2018] [DeLoach and Lyle 2009] [Deng and Cao 2020] [Dhote et al 2025] [Do and deWeck 2011] [Dong et al 2018] [Douglas Aircraft Co Long Beach Ca 1962] [Doule et al 2019] [Euler 1971] [Evaluation of certain crushable 1962] [Experimental Test and Analysis 2021] [Fasanella 1986] [Feld 1968] [Feld 1968] [Fisher, Lloyd J., Jr. 1960] [Foster 1952] [Fu et al 2017] [Gay, Robert S. 2011] [Gohmert 2009] [Guida et al 2013] [Guo et al 2023] [Haberman et al 2012] [Hackenberger and Mattenson 1965] [Hammel 2004] [Hansen, Chris and Tsai, Ted 1994] [Harding 1964] [Bixby 1962] [He et al 2014] [He et al 2015] [He et al 2024] [Hinchey 1968] [Hodell and Rosner 1957] [Hoffman, E. L. et al 1961] [Hu et al 2014] [Huang 2019] [Huxley-Reynard 2001] [Hwang and Han 2024] [Hwang et al 2024] [Isaac 2020] [Isaac and Duddeck 2022] [Isaac and Ezekwem 2021] [Jackson et al 2002] [Jones 1970] [Joyner 1970] [Littell and Putnam] [Kellas and Corliss 2002] [Kellas et al 2010] [Kim et al 2014] [Klaus 2018] [Klumpp 1968] [Labun 2005] [Landing Loads 1996] [Lee et al 2008] [Lei et al 2024] [Li et al 2011] [Li et al 2026] [Liang and Ji 2021] [Littell 2014] [Littell et al 2019] [Littell, Justin D. et al 2010] [Liu et al 2007] [Lu et al 2015] [Lv et al 2022] [Majumder and Rao 2009] [Marquet and Pragluski 1968] [Mennu et al] [Mazelsky et al 1963] [Mazelsky et al 1973] [McCABE et al 1967] [Merchant and Sawdy 1970] [Merchant and Sawdy 1971] [Meriwether and Harris 1962] [Meriç and Gedikli 2021] [Merz et al 1971] [Mitchell 1963] [Mou et al 2015] [Nebylov and Nebylov 2024] [Newby et al 2018] [Norman and Kiker 1967] [Otsuki et al 2017] [Paletta et al 2011] [Paletta et al 2015] [Patterson and Glaab 2012] [Paz Mendez et al 2019] [Peng and Ortiz 2006] [Peterson 1961] [Petrov et al 2022] [Pfeiffer 1955] [Phillips et al 1973] [Pimenta and Robinson 2014] [Purtle et al 1995] [Qiu 2007] [Rao 1984] [Read and Muszynski 1994] [Ren et al 2017] [Hilderman et al 1967] [Rivellini 1994] [Roithmayr and Pei 2024] [Ruan et al 2026] [Saeki 2013] [Saeki et al 2015] [Saleh et al 2017] [Saleh et al 2019] [Schröder et al 2017] [Shah and Topa 2015] [Shen and Liu 2025] [Shen et al 2025] [Shook et al 2009] [Slade et al 2006] [Smith et al 2007] [Son and Huda 2019] [Stubbs 1968] [Stubbs, Sandy M. 1965] [Talekar et al 2021] [Thomas and Tiwari 2019] [Timmers et al 2009] [Tutt et al 2009] [Tutt et al 2009] [Tuttle et al 2020] [Vergnolle 1995] [Walton et al 1964] [Wang et al 2022] [Wang et al 2023] [Wang et al 2026] [Waye et al 1995] [Wei and Nie 2005] [Wei et al 2015] [Welch 2007] [Williamson and Likins 1968] [Xiang and Zhou 2025] [Xie et al 2021] [Xie et al 2023] [Xing et al 2023] [Xu and Wang 2026] [Xu et al 2019] [Yamada et al 2015] [Yan and Wang 2014] [Yan et al 2025] [Yang et al 2014] [Yin and Wen 2012] [Yin et al 2017] [Yin et al 2021] [Yu et al 2015] [Zanoosi et al 2021] [Zeb et al 2026] [Zhang and Wang 2024] [Zhang et al 2023] [Zhou et al 2018] [Zhou et al 2019] [Zhou et al 2022] [Zhou et al 2023] [Zhou et al 2024] [Zhu et al 2020] [Zhu et al 2021] [Zhu et al 2025] [Zhu et al 2026] [Zou and Yao 2024]

Parachute recovery of spacecraft, boosters and aircraft

Round-canopy recovery of particular vehicles. The Apollo, Gemini, Orion and sample-return parachute systems, booster and stage recovery, and recovery systems for aircraft and unmanned aircraft.

166 records. [Comis and Machin 2019] [Morris and Hill] [Ali et al 2017] [Alizadeh et al 2014] [Anderson et al 2017] [Anderson et al 2019] [Apollo 15 mission main 1971] [Aubuchon 2013] [Aubuchon et al 2011] [Bacchus et al 1975] [Bai et al 2022] [Banerjee and Utreja 1975] [Barnard 1985] [Behr 1989] [Bledsoe 2013] [Boltz 2000] [Brearley 1969] [Butler and Montanez 2007] [Carten and Wuest 1979] [Carten and Wuest 1980] [Cassanto, J. M. et al 1968] [Catch a Falling Star 1993] [Clifford and Hengel 2009] [Cowan et al 2025] [Currin et al 2011] [Daum 2019] [Daum and Mollmann 2017] [Daum, Jared S. and Petersen, Michael L. 2019] [Dickinson et al 1972] [Dinh] [Drynan] [Eckstrom 1975] [Eckstrom, C. V. 1975] [Edwards et al 2024] [Ray and Janssen] [Fallon 1991] [Farhall et al 2007] [French 1965] [French 1988] [Gao et al 2022] [Genesis parachute failure investigation 2005] [Kesler 2026] [Guidotti et al 2012] [Hahne and Fremaux 2008] [Harris and Christenson 2018] [Hennings et al 2015] [Higgins and Speelman 1973] [Inatani et al 1999] [Irving Air Chute-Brake Parachute 1968] [Janda et al 2011] [Janda et al 2013] [Daum 2026] [Jastrzębski et al 2018] [Jasztal and Kłosiński 2024] [Jasztal et al 2022] [Jia et al 2014] [John et al 2025] [Johnson 1986] [Johnson 1989] [Just 1991] [Shafner et al] [Jóźko and Włodarczyk 2020] [Kanai et al 2018] [Kim 2016] [Knacke 1985] [Kolesar et al 2013] [Koster et al 2011] [Kozlov 2013] [Kross and Webb 1979] [Kumar et al 2023] [Lichodziejewski et al 2009] [Lubey et al 2010] [Lyalin and Morozov 2005] [Machin et al 2007] [Machin et al 2011] [Machin et al 2011] [Mahajan et al 2025] [Mansfield 1973] [Maru et al 2026] [Matz and Braun 2015] [Mickey et al 1970] [Moog and Kross 1982] [Moog, R. D. et al 1979] [Moore 2011] [Moore 2011] [Moore and Fraire 2013] [Moore and Romero 2013] [Moorman and Yechout 2009] [Morris 2022] [Morris and Hill 2026] [Morris and Olson 2011] [Morris et al 2009] [Morris and Olson 2011] [Morris et al 2011] [Morris et al 2011] [Neustadt et al 1967] [Norgard 2012] [Norgard 2012] [Oguz and Salazar 2011] [Paul and Paul 2023] [Pepermans et al 2018] [Pepper 1977] [Pepper 1980] [Pepper and Fellerhoff 1969] [Pepper and Wailes 1989] [Placco 2024] [Priyadarshi et al 2020] [Qiu et al 2021] [Quadrelli et al 2004] [Ray 2017] [Ray 2019] [Ray et al 2019] [Ray, Eric S. 2011] [Reinhard et al 1997] [Roland et al 2016] [Romero and Ray 2013] [Ross and Schuster 2014] [Runkle and Woodis 1979] [Janssen et al] [Sandstrom 1971] [Sengupta 2013] [Sengupta et al 2011] [Sengupta et al 2012] [Shyu and Hsiao 2014] [Silbert et al 1986] [Space shuttle solid rocket 1973] [Specification for Aircraft Emergency] [Standard Specification for Aircraft] [Stewart, Christine E. 2013] [Takayanagi et al 2021] [Takizawa et al 2011] [Tannehill 1978] [Taylor et al 2009] [Terahara et al 2025] [Tezduyar and Takizawa 2026] [Thomas and Thomas 2008] [Tiaden and Yakimenko 2008] [Tiaden and Yakimenko 2009] [To] [Varela and Ray 2013] [Varela and Ray 2013] [Vincze 1966] [Vishnyak 1995] [Von Eckroth, Wulf et al 1991] [Vu et al 2021] [Wang 1999] [Waye et al 1986] [Wei 1991] [Whalley 1973] [Williamson 1979] [Witkowski 1999] [Witkowski 2010] [Witkowski et al 2022] [Witkowski et al 2026] [Wolf 1991] [Wolf, Dean and Runkle, Roy E. 1995] [Wu et al 2019] [Wu et al 2020] [Wyllie 2001] [Xie et al 2015] [Yakimenko et al 2008] [Yeakle et al 2009] [Yechout et al 2011] [Yıldırım Dalkıran and Kırteke 2024] [Zakaria 2013] [Zhu et al 2021]

Supersonic, planetary and inflatable decelerators

Decelerators at high speed and on other worlds. Supersonic and planetary parachutes, ballutes and inflatable decelerators, from Viking to the Low Density Supersonic Decelerator.

165 records. [Adams 2014] [Alexander, W. C. and Foughner, J. T., Jr. 1973] [Babakov 2025] [Baginski et al 2014] [Baker] [Bendura et al 1968] [Bendura et al 1974] [Bohon and Miserentino 1970] [Boustani et al 2019] [Boustani et al 2020] [Boustani et al 2022] [Brandeau et al 2015] [Campbell 1966] [Canning and Edwards 1988] [Whitlock et al 1967] [Whitlock et al 1967] [Clark and Braun 2008] [Clark et al 2015] [Clark et al 2017] [Clark et al 2021] [Coltrane et al 1968] [Connors 1963] [Contreras 2012] [Cook et al 2013] [Corridan, R. E. et al 1984] [Cruz et al 2014] [Cruz and Snyder 2017] [Cruz, Juan R. et al 2013] [Darnell et al 1968] [Darnell et al 1968] [Davenport 1969] [Deitering and Hilliard 1965] [Desai et al 2005] [Dickinson et al 1972] [Downing et al 1956] [Dutta et al 2016] [Eckstrom and Mayhue 1969] [Eckstrom and Preisser 1968] [Eckstrom et al 1967] [Eckstrom, Clinton V. 1970] [Eckstrom, Clinton V. and Preisser, John S. 1967] [Eckstrom, Clinton V. and Preisser, John S. 1968] [Flow Studies of Decelerators 1959] [Foughner and Alexander 1974] [Cadieux et al] [Gaborit et al 2005] [Galigher 1969] [Gallon and Witkowski 2015] [Gallon et al 2015] [Gallon et al 2013] [Gates et al 2010] [Gidzak et al 2008] [Gillis 1973] [Gnoffo and Anderson 2002] [Gong and Wu 2021] [Gonyea, Keir C. et al 2013] [Goulding and Adams 2010] [Guy 1969] [Harris and Christenson 2019] [Heinrich 1966] [Heinrich et al 1959] [High-Speed Schlieren Movies of 1960] [Hinada et al 1991] [Homan 1970] [Houmard 1973] [Huang et al 2022] [Hussong and Lau 1970] [Ivanov 2015] [Jia et al 2024] [Jiang et al 2022] [Cruz] [Cruz et al] [Karlgaard and “O’Farrell 2022] [Kerzhanovich et al 2000] [Koenig et al 1995] [Kornuta and Guo 2010] [Kou and Zhan 2022] [Lau 1970] [Lorenz 1993] [Lorenz and Allen 2023] [Lorenz et al 2021] [Lowry 1964] [Lowry et al 2022] [Manjith 2026] [Mannan et al 2026] [Mastropietro et al 2015] [Mastropietro et al 2013] [Mayhue and Bobbitt 1972] [Mayhue and Eckstrom 1969] [Maynard 1961] [McMenamin and McMenamin 1997] [McMenamin and Pochettino 1984] [Meyer 1958] [Mickey 1966] [Mickey and Stuart 1967] [Miller et al 2003] [Mobley et al 2016] [Moog and Michel 1973] [Moog et al 1973] [Muppidi et al 2018] [Muppidi et al 2018] [Muppidi et al 2019] [Murrow and McFALL 1969] [Murrow et al 1973] [Murry and Randolph 2016] [Nelsen 1995] [Nie et al 2023] [O’Farrell and Clark 2024] [O’Farrell et al 2016] [Pedersen 1961] [Pepper 1969] [Pepper 1984] [Phillippe et al 2024] [Placco 2023] [Placco et al 2025] [Preisser et al 1967] [Pyle et al 1973] [Queen and Raiszadeh 2006] [Rabinovitch et al 2018] [Rabinovitch et al 2020] [Rabinovitch et al 2022] [Redmond et al 2014] [Reichenau 1972] [Rhudy 1969] [Rychnovsky and Everett 1975] [Sengupta 2011] [Sengupta et al 2008] [Sengupta et al 2009] [Sengupta, Anita et al 2007] [Sims 1963] [Dutta 2020] [Steinberg et al 1974] [Taeger et al 2007] [Taguchi et al 2021] [Takabayashi and Kitamura 2019] [Takabayashi et al 2019] [Tanner, Christopher L. et al 2015] [Taylor et al 2006] [Timmons 1976] [Turk 1966] [Usry 1969] [Usry 1968] [Van Norman et al 2016] [Votta et al 2010] [Whitlock et al 1973] [Whitlock, Charles H. et al 1968] [Witkowski 1999] [Witkowski 2007] [Witkowski et al 2019] [Wolf and Ivanov 2008] [Worth 1966] [Xing and Liang 2025] [Xue and Nakamura 2011] [Xue and Nakamura 2013] [Xue et al 2013] [Xue et al 2015] [Xue et al 2016] [Xue et al 2019] [Xue et al 2019] [Xue et al 2022] [Yang 2021] [Yang et al 2017] [Yang et al 2018] [Yang et al 2019] [Zhao and Li 2019]

Spaceflight deconditioning and orthostatic intolerance

The medical constraint on the entry load. Post-flight orthostatic intolerance, cardiovascular deconditioning, their ground analogues and countermeasures.

154 records. [Aarotale and Henriksen 2020] [Hoyt et al 2021] [Ap et al 2025] [Arbeille and Herault 1998] [Arc-Chagnaud] [Avula 1981] [Baisch et al 2000] [Bačkorová and Lazúrová 2023] [Beck et al 1989] [Beckers et al 2007] [Bed Rest Muscular Atrophy 2004] [Billica and Kraft 1997] [Blaber et al 2004] [Blaber et al 2011] [Blaber et al 2023] [Blomqvist et al 1994] [Buckey 1991] [Buckey et al 1996] [Bungo and Johnson 1983] [Bungo et al 1985] [Burkhart and Kirchoff 1977] [Charles 1993] [Charles et al 1992] [Charles et al 2009] [Chobanian et al 1974] [Computer simulation studies in 1985] [Convertino 1987] [Convertino 2002] [Convertino and Sather 2000] [Convertino et al 1986] [Cowings et al 1991] [Cowings et al 1993] [Cowings et al 1994] [Cowings et al 1994] [Cowings et al 2013] [Davis 1989] [Davis and Fortney 1997] [Deconditioning and Reconditioning 2000] [Deconditioning and Reconditioning 2004] [Diedrich et al 2014] [Effects of Deconditioning and 2004] [Ertl et al 2000] [Etter and Sharp 2010] [Fan et al 2019] [Feiveson et al 2014] [Fernandez-Gonzalo et al 2025] [Fortney 1991] [Fortney et al 1991] [Free Radical Processes in 2004] [Frett et al 2023] [Fuchs 1983] [Gaffney 1987] [Gallo et al 2020] [Goldwater 1991] [Granberry et al 2020] [Greenleaf and Bosco 1969] [Greenleaf et al 1972] [Greenleaf et al 1973] [Hamilton et al 2011] [Hao et al] [Hardy 2024] [Harrison and Kates 1982] [Hasser and Moffitt 2001] [Heldt and Mark 2005] [Heldt et al 2002] [Hinghofer-Szalkay and Rossler 2005] [Hutchinson] [Hyatt and West 1977] [Iellamo et al 2018] [Ivkovic and Mukai 2006] [Jacobs and Doherty 2011] [Charles and Boettcher 1994] [Johnson et al 1973] [Kaufman et al 2006] [Keil and Ellis 1976] [Kim et al 2026] [Kryvoruka 1976] [Lathers and Charles 1993] [Lee] [Lee et al 2006] [Lee et al 2011] [Lee et al 2015] [Lee et al 2017] [Leonard and Srinivasan 1985] [Levine et al 1997] [Levine et al 2009] [Ludwig et al 1992] [Luty 2009] [McGrew et al] [McCluskey 2004] [Mechanisms of Orthostatic Intolerance 1997] [Meck et al 2004] [Meck et al 2001] [Melby et al 2005] [Melchior and Fortney 1993] [Miller 1965] [Moore 2004] [Moore et al 2005] [Moore et al 2013] [Moore et al 2001] [Paloski et al 2004] [Pawelczyk and Levine 1999] [Pawelczyk et al 2001] [Perhonen et al 2001] [Platts et al 2008] [Platts et al 2010] [Platts et al 2014] [Platts et al 2015] [Platts et al 2011] [Ramsdell et al 2001] [Raven and Alexander 1985] [Reed and Wood 1967] [Sandler et al 1983] [Jarvis et al 2007] [Schlader et al 2016] [Schlegel et al 1999] [Schneider 2000] [Schneider et al 2002] [Schondorf et al 2001] [Schroeder et al 2002] [Serrador et al 2000] [Shi et al 2003] [Shimizu et al 1979] [Shoemaker et al 1999] [Shvartz et al 1977] [Siconolfi et al 1996] [Snow 1996] [Srinivasan and Leonard 1983] [Srinivasan et al 1992] [Stenger et al 2010] [Stenger et al 2010] [Stenger et al 2010] [Streeten 1999] [Summers et al 2010] [Suzuki et al 2014] [The Brittle Bones of 2004] [Thermoregulation during Deconditioning 2004] [Ueno et al 1994] [Understanding the Mechanisms of Post-Spaceflight Orthostatic Intolerance for Developing Effective Countermeasures 2011] [van Lieshout 2003] [Varghese and Pleticha 2026] [Vaziri and Purdy 2003] [Vernikos and Convertino 1994] [Vernikos et al 1991] [Water Immersion Deconditioning in 2004] [Wieling et al 2002] [Williams et al 1994] [Wood et al 2019] [Xiao et al 2002] [Yajima et al 1992] [Yates et al 2003] [Yates and Kerman 1998] [Zhang et al 1997] [Zidon]

The constraint is studied in flight and on the ground. Of the 154 records, 75 name spaceflight, astronauts, flight or landing in their titles, and 34 more name only a ground analogue such as bed rest, head-down tilt, lower body negative pressure, immersion or parabolic flight.

The X-38 and crew return vehicles

The vehicle and its predecessors. The X-38 and its subsystems, the Assured Crew Return Vehicle studies and other station rescue vehicles.

127 records. [Ahmed, Raf et al 2003] [Ahne et al 1989] [Anderson 2001] [Anderson 1991] [Anderson and Armitage 1992] [Assured crew return vehicle 1991] [Bedos, Thierry and Anderson, Brian L. 1999] [Behr et al 2001] [Behr et al 2001] [Bennett and Fox 2003] [Bennett et al 1999] [Berry et al 2001] [Berry, Scott A. et al 1997] [Bossi et al 1989] [Bosworth and Stachowiak 2005] [Burgio et al 1993] [Campbell 2025] [Campbell et al 1996] [Chandler 1992] [Cooper et al 2005] [Costa et al 2000] [Cruz et al 1990] [Cruz et al 1993] [Curry 2000] [Curry et al 2001] [D A Stone et al 1991] [Darcy 2002] [Darcy and Barrera 1989] [Darcy and Johnson 2000] [Darcy and Strangways 1999] [Darcy 1998] [Delgado and Arcioni 2000] [Delgado et al 2000] [Delgado et al 2001] [Dingell and Hurlbert 1997] [Dingell et al 1999] [Dingell et al 2009] [e-CRV - Design study 2004] [Eckhardt 2001] [Fasanella, Edwin L. et al 2000] [Flanary et al 2003] [Foti 1999] [Gafka, George K. and Daugherty, Robert H. 2000] [Gillespie and Saha 2003] [Gomez 2002] [Good Enough for the 2001] [Goodman 2005] [Hagen et al 2004] [Haubelt et al 2001] [Hertz 2003] [Hong 1999] [Hook and Freeman 1989] [Hooks and Stone 1992] [Horvath, Thomas J. et al 1990] [Horvath, Thomas J. et al 2000] [Hosterman and Anderson 1991] [Hosterman and Anderson 1990] [Hu et al 2023] [Kittredge and Hunt 2001] [Komerath, N. M. et al 1998] [Kouba,Coy et al 2003] [Krupa 1990] [Labbe, Steve G. et al 1999] [Loomis et al 2004] [Lunan 2001] [Lupo et al 2004] [MacConochie, Ian O. 2000] [Machin et al 1999] [Machin et al 2001] [Machin, Ricardo A. 2000] [Madsen et al 2003] [Maloy and Machin 2003] [Mazanek et al 1997] [McCleskey et al 2000] [Merret and Bragg 2003] [Micol, John R. 1990] [Montella et al 2025] [Montella et al 2025] [Munday 2000] [Munday, Steve et al 2000] [Myers 1990] [Naftel et al 1990] [Nettleblad and Johnston 2002] [Neville] [Peterson 1992] [Peterson, Wayne L. 2004] [Petro 1995] [Preliminary subsystem designs for 1990] [Preliminary Subsystem Designs for 1990] [Preliminary subsystem designs for 1990] [Project EGRESS Earthbound Guaranteed 1990] [Project EGRESS The design 1990] [Raiman 1991] [Ranier 2001] [Rice and Cheng] [Rugless et al 2002] [Sepahban 1992] [Sepahban and Williams 1993] [Sgobba and Osetskiy 2026] [Shin et al 1999] [Shin et al 2001] [Simpson et al 2000] [Simpson et al 1999] [Smith et al 1990] [Smith et al 1999] [Stein et al 2005] [Stein, Jenny M. 2005] [Stein, Jenny M. et al 2005] [Stein, Jenny M. et al 2007] [Stepaniak et al 2001] [Strahan 2003] [Strahan 2001] [Kowal 1999] [Tongue et al 1997] [Viviani and Pezzella 2015] [von Bengtson 2005] [Wacker, Roger et al 2001] [Ware 1989] [Ware, George M. 1989] [Ware, George M. et al 1989] [Weilmuenster, K. James et al 1990] [Weilmuenster, K. James et al 1991] [Welge et al 2000] [Wu et al 2001] [X-38 Phase 3 Drops 2000] [Yang et al 2017] [Semenov et al 1993]

The vehicle’s own literature stops with the programme. Of the 66 titles in the survey that name the X-38, 62 date from 2006 or earlier, 2 from 2007 or later and 2 are undated.

Crew safety, escape, abort and spaceflight risk

The wider problem the lifeboat answers. Crew escape and abort systems, crew survivability, spaceflight risk assessment, medical risk and medical operations aboard a station.

123 records. [Agarwal 2019] [Bader and Coleman 1967] [Tobias and McMillan] [Bogomolov et al 2019] [Bogomolov et al 2019] [Bogomolov et al 2019] [Bogomolov et al 2020] [Bogomolov et al 2020] [Bouchey and Delborne 2014] [Boyer et al 2018] [Boyer 2010] [Boyer et al 2019] [Bronnikov et al 2019] [Bue et al 2009] [Carr and Lagimoniere 2013] [Childress et al 2023] [Christensen 2017] [Cohen and Junge 1984] [Craig 1993] [Crowther 2011] [Levin et al 2023] [Davidescu et al 2026] [Davidson et al 2008] [Decadi 2021] [Deger et al 2005] [Dervay et al 2021] [Designing an Astronaut Emergency 2021] [Di Campli Bayard de Volo and Di Pietro 2018] [Munster et al] [Munster et al] [Duncan et al 2007] [Dutton 1993] [Dutton 1993] [Dutton 1994] [Evans, Hilary J. et al 2019] [Evans et al 2002] [Fabian 1990] [Fitts et al 2008] [Gadsby 1993] [Gadsby et al 1992] [Gerstenmaier 2017] [Go et al 2014] [Guo and Zhan 2026] [Heck 1993] [High and Vassar 1996] [Hyde et al 2018] [Imada et al 2009] [Jackson and Rivers 1998] [Jackson et al 1993] [Jackson et al 1994] [Jackson et al 1994] [Jana et al 2021] [Cochrane and Graham 1971] [Jones 1966] [Koontz et al 2020] [Kotov et al 2021] [Krevor et al 2011] [Lakshmi et al 2021] [Langston 2016] [McIntyre et al] [Lebedev and Evseenko 2021] [Lengyel et al 2019] [Levin 2026] [Li et al 2023] [Liever and Habchi 2004] [Lindsay et al 2026] [Lowe] [Luciani and Pierce 1986] [Lutomski et al 2010] [Lutomski 2011] [M2-F2 Lifting Body Accident 1967] [Prelich et al 2025] [McCARTHY et al 1968] [McCauley, R. et al 2015] [McHenry 1980] [McPhee and Baumann 2025] [Menshenin and Crawley 2019] [Millard et al 1989] [Mohammadi Amin et al 2020] [Newby et al] [Naftel and Talay 1993] [Ocampo and Klaus 2013] [Oubre et al 2014] [Owens and Aubuchon 2011] [Pandya 2008] [Pardini and Anselmo 2022] [Pedersen 1986] [Piacentino et al 1978] [Prassinos et al 2010] [Price and Earl A. 1970] [Raftery and Fox 2007] [Ray and Bishop 1994] [Reding and Svendsen 1988] [Meshell and Hark] [Rock and Habchi 1997] [Rosales and Stoltzfus 2009] [Ryan 2023] [Sakaue et al 2020] [Saravanan et al 2021] [Sarigul-Klijn et al 2011] [Seeney et al 1968] [Sgobba and Kezirian 2016] [Shaffer and Brinkley 1974] [Sheeran et al 2023] [Shelhamer et al 2024] [Smith and Tresch 2019] [Smitha et al 2021] [Somanath et al 2021] [Sparks and Raney 2007] [Sreenivasulu et al 2021] [Stamatelatos et al 2011] [Tartabini et al 2016] [Tauby 1979] [Taylor and Zaloguev 1976] [Thompson 1964] [Tobias and Hawkins 2005] [Tobias and Hawkins 2005] [Houser et al] [Vicente Martínez et al 2026] [Vv 2009] [KThompson et al] [Wang et al 2013] [Williams-Hayes 2007]

Parachute textiles, lines and structural testing

What the canopy is made of. Canopy fabrics and their permeability, suspension lines, seams, risers, mortars and cutters, and canopy stress measurement.

107 records. [Alley and Faison 1970] [Amirkhizi et al 2024] [Anton et al 2023] [Appel and Worner 1931] [Aume et al 1983] [Bacchus and Henke 1978] [Baker and Swallow 1956] [Barry et al 2026] [Behera et al 2022] [Bergeron et al 2009] [Bickford et al 1955] [Bielecka et al 2025] [Bullock 1980] [Campos 1977] [Cates 1956] [Chu et al 1956] [CLOTH, PARACHUTE, ARAMID, Intermediate] [Cloth, Parachute, Meta-Aramid, LOW] [Cloth, Parachute, Meta-Aramid, Low] [Cooke and Catherine Lenehan 1973] [Coskren and Chu 1963] [Dormois] [Dyess and William W. 1976] [Egorova 2025] [Ericksen et al 1984] [Ericksen et al 1992] [Experiments with Omega sensors 1979] [Farkas 1963] [Farrimond 1989] [Figucia and McCafferty 1966] [Figucia et al 1968] [French 1979] [French 1980] [g/m 2 nylon parachute fabric] [g/m 2 nylon parachute fabric] [Gao et al 2017] [Garrard and Muramoto 1982] [Garrard et al 1987] [Goglia 1952] [Goglia et al 1955] [Greathouse and Schwing 2015] [Grim et al 2023] [Han et al 2013] [Heinrich 1966] [Heinrich 1979] [Hoffman 1971] [Iyer 2023] [Iyer 2023] [Jo et al 2022] [Shafner et al] [Khudaiberdiev 1984] [Konicke and Garrard 1982] [Kozlov and Kiselev 2024] [Kulkarni 1992] [Křemenáková et al 2026] [Laub et al 1974] [Lavier 1955] [Lavier 1955] [Lavrakas 1955] [Lavrakas and Katz 1955] [Li and Yu 2026] [Ma and Zu 2015] [Mahar et al 1973] [Makarov et al 2018] [Makarov et al 2022] [Matthews and White 1973] [McCarty 1978] [Militký et al 2025] [Miller 1954] [Miller 1956] [Mollmann 2015] [Mollmann 2017] [Mollmann 2017] [Nichols 1983] [Niemi 1989] [Parachute washing system 1996] [Pereborova et al 2022] [Peterson et al 1986] [Phillippe et al 2024] [Pleasants 1974] [Pleasants 1973] [Pleasants 1975] [Poole 1973] [Poole 1973] [Preisser and Greene 1970] [Raj and Devi 2021] [Ravnitzky 1989] [Scott et al 1968] [Shepardson 1954] [Shumway et al 2022] [Sickles and Lawrence 1991] [Siefers et al 2017] [Singh et al 2017] [Skelton and Abbott 1974] [Specification for mercerized cotton] [Spence 1970] [Structural and permeable contortion 2024] [Sullivan 1944] [Sun et al 2025] [Sweeney 1955] [Temnenko 1994] [Templeton 1956] [Teng and Li 2017] [The measurement of pull forces for parachute ripcord release 1980] [Tomcsak 1960] [Yu et al 2025] [Zwicker and Sinclair 2013]

Thermal protection of entry vehicles

The heat shield that was never flown. Ablative, ceramic and metallic thermal protection, hot structures, seals and the testing of thermal protection for entry.

96 records. [Adami et al 2015] [Ai et al 2022] [Ajja] [Alba and Greendyke 2016] [Alba et al 2016] [Arnold et al 2005] [Baker and Kramer 1982] [Bauer and Kummer 1966] [Beck et al 2015] [Belz et al 2011] [Blosser 2002] [Boehrk et al 2019] [Bouslog et al 1992] [Chen, George et al 2007] [Chin et al 1964] [Cunnington et al 1983] [Curtin 2026] [Daryabeigi et al 2006] [Davis 1969] [Davis et al 2013] [Dec and Braun 2006] [Di Caprio et al 2021] [Diaconis et al 1961] [Dolan 1970] [Dolan et al 1966] [Dunlap and Steinetz 2003] [Emery and Bardot 2006] [Fan 2015] [Ferguson et al 2006] [Fisher et al] [Fujino and Ishikawa 2006] [Genaro and Pessoa Filho 2006] [Gogu et al 2007] [Gogu et al 2009] [Guoling and Ji 2014] [Hald and Ullmann 2003] [Han et al 2023] [Hardy et al 2005] [Hierarchical Composite with Self-Adaptive] [Huo et al 2015] [Jits et al 2005] [Johnson et al 2007] [Koenig et al 2019] [Kolodziej and Rasky 2003] [Komine and Kobayashi 1982] [Koo and Mensah 2017] [Kowal 2010] [Kumar and Mahulikar 2017] [Lacombe and Rouges 1990] [Le and Goo 2025] [Litvintsev et al 2019] [Machado 2018] [Martin and Boyd 2008] [Martinez et al 2011] [Mazzaracchio and Marchetti 2010] [McCOWN and Davi 1967] [Mitchel 1971] [Mooij 2014] [Mullen] [Ogasawara and Ishikawa] [Orlik-Ruckemann 1968] [Panerai et al 2011] [Park and Shin 2024] [Patel 2026] [Pitts and Kourtides 1989] [Reinikka and Sartell 1965] [Reinikka and Wells 1963] [Reinikka and Wells 1964] [Ruperti et al 2004] [Schonberg and Squire 2024] [Scoville and Rajula 2005] [Sepka et al 2013] [Shang and Surzhikov 2010] [Sharma et al 2008] [Shin et al 2023] [Sipe and Hinde 2008] [Smith et al 2013] [Sutton 1982] [Tancredi and Grassi 2007] [Thermal performance evaluation of 1972] [Thermal Protection for a Re-Entry Vehicle Using Heat Ablation Process 2015] [Thermal Protection System Conception 2013] [Triantou et al 2017] [Triantou et al 2017] [van den Abeelen 2016] [Vander Kam and Gage 2021] [Venkatapathy, Ethiraj and Reuther, James 2008] [Vivek Jacob 2025] [Williams et al 1995] [Williams et al 1993] [Wright et al 2006] [Yamada and Inatani 2002] [Yamada et al 2002] [Yoshino et al 2010] [Zhu et al 2016] [Zhuang and Ridley 2024]

Human tolerance of acceleration and impact

What an occupant survives. Human tolerance to sustained and impact acceleration, in man and in animal models, and its protection.

95 records. [A Predictive Model of 2010] [A Study of the 1962] [Allan and Crossley 1972] [Averkin et al 1965] [Barazanji] [Bartlett 1950] [Becker 1973] [Begeman et al 1973] [Berger and Weiss 1983] [Buick et al 2003] [Burns and Smith 1983] [Burton 2006] [Chambers 1963] [Cheng et al 1979] [Cochran et al 1954] [Creer et al 1960] [Creer et al 1960] [Crisman and Burton 1988] [Deepika et al 2021] [Dickey et al 1982] [Eiband 1959] [Ewing 1971] [Ewing and Thomas 1973] [Ewing et al 1973] [Ewing et al 1975] [Ewing et al 1977] [Feller and Neville 1966] [Foley] [Gallagher et al 2006] [Glaister 1978] [Glebova et al 2022] [Greenleaf et al 1966] [Greenleaf et al 1999] [Greenleaf et al 2001] [Greenleaf et al 2002] [Greiner 1956] [Grygoryan 2002] [Hawkins and Hessberg 1961] [von Gierke and Brinkley 1975] [Hodgson 1973] [Holcomb 1960] [Hrebien and Hendler 1983] [Human Tolerance to Impact] [Huntoon 1989] [Hyde and Raab 1965] [Impact Acceleration Stress 1962] [Impact Acceleration Stress. Proceedings 1962] [Jackson 1996] [Jacobson et al 1974] [Pattarini et al 2020] [Jennings et al 1986] [King 1985] [King and Hodgson 1979] [Klein et al 1980] [Kornhauser and Lawton 1961] [Krutz et al 1975] [Krutz et al 1990] [Kuroda 1966] [Laananen 1980] [Lawrence, Charles et al 2008] [Ma et al 2021] [Mather 1968] [McCormick] [McKenney 1970] [Mital et al 1978] [Mohler et al 1987] [Moroz and Kriventsov 2013] [Muzzy and Lustick 1976] [Pelligra et al 1972] [Pelligra et al 1973] [Polish Studies on Human 2015] [Prasad et al 1975] [Reeves 1961] [Reeves 1961] [Robbins 1978] [Rositano 1980] [Sandler et al 1977] [Self et al 1996] [Shender 2000] [Smith 1978] [Stiehm 1961] [Stålhammar and Olsson 1975] [Symposium on the Impact 1961] [Takeuchi 1966] [Tolerance to +G acceleration 2006] [Tripp et al 2006] [Vernikos-Danellis et al 1978] [Walker et al 2009] [Watkins and Guccione 1992] [Whinnery 1988] [Whinnery and Murray 1990] [Williams et al 1990] [Wood et al 1974] [Zarriello et al 1958] [Ziejewski and Anderson 1996]

The space station programme and the vehicles that serve it

The station the vehicle served. Station programmes, configuration, operations, cost and policy, and the transfer, docking and resupply vehicles that serve a station.

86 records. [A health care system 1992] [Abrahamson 1983] [Ambrus and Herman 1988] [Anderson and Carlisle 1983] [Apollo-Soyuz test project. Operations 1974] [Baker 1987] [Bayt and Lueders 2016] [Beardsley and Schaefer 1987] [Beggs 1985] [Bekey 1983] [Bennett 1986] [Blesma 1997] [Bluth 1986] [Brunner and Byerly 1990] [Chandler 1985] [Colladay 1983] [Cook 1983] [Curry and Prokhorov 2006] [D.II.4.5 Code of] [Delauer 1983] [Deryder, L. J. 1988] [Dischinger 2006] [European Space Agency 1999] [European Space Agency 1999] [European Space Agency 1999] [Farrand 1987] [From spacelab to space station 1986] [Garegnani and Allen 1990] [Ge et al 2020] [Gibson 1986] [Gould et al 1991] [Gould et al 1992] [Gray 1985] [Harris 2002] [Hodge 1983] [Hosmer 1986] [Kallay 1966] [Keyes 1986] [Lam 1979] [Law and the space station 1986] [Logsdon 1985] [Logsdon 1987] [Logsdon 1991] [Low 1975] [Lubin et al 1992] [Macauley 1986] [March 1988] [Matsunaga 1986] [McCurdy 1988] [Meredith et al 1990] [O’Brien 1987] [Open for business: a new approach to commercialisation of the International Space Station 2000] [Pace 2023] [Parrish 1990] [Paules 1986] [Paules et al 1987] [Peplow 2004] [Pritchard 1983] [Richardson 2000] [Russell et al 2006] [Sadeh 2004] [Shah et al 2014] [Shinkle 1985] [Shkedi 2005] [Snedeker 2000] [Space station role 1986] [Space station systems analysis 1977] [Stokes and Williams 1992] [Strachan 2000] [Strachan et al 1999] [Thirkettle et al 1993] [Thirsk et al 2009] [Thomas et al 2000] [Troutman et al 1993] [Turett 2016] [Uhran 2000] [Syromyatnikov 1972] [Vallerani 1986] [Van Allen 1986] [van den Abeelen 2016] [van den Abeelen 2016] [von Kries 1987] [Wassersug 1994] [Wissinger 1988] [Woodcock 1983] [Yakovenko 1999]

Deorbit, landing opportunities and landing sites

Leaving orbit for a chosen place. Deorbit guidance and targeting, deorbit propulsion, landing opportunities and landing site coverage.

25 records. [Cianciolo] [Baldwin] [Baldwin and Lu 2012] [Baldwin et al 2009] [Bedford 1976] [Brown 1977] [Cox 1971] [Dong et al 2025] [Galman 1966] [Galman 1971] [Green et al 1968] [Hastings 1993] [Heath et al 1977] [Leonard and Joseph 1966] [Martikan 1965] [Penzo 1990] [Schneider 1966] [Stern 1966] [Stern and Chu 1963] [Sternberg et al 2019] [STS-29 Post-Insertion/Deorbit Prep and 1989] [Sun 1982] [Tempelman 1973] [Vinh and Johannesen 1985] [Zhang and Li 2018]

Loads on the parachutist, opening shock and landing injury

The human end of the decelerator. Loads on the body during parachute opening and landing, and the injuries they cause.

24 records. [Aziz and Zainal 2026] [Cao et al 2026] [Jiang et al 2023] [Knapik 2019] [Lazzari et al 2025] [Lillywhite 1991] [Lo Martire et al 2015] [Loebel et al 2018] [Lord 1944] [McBratney et al 2014] [Mellen 1989] [Niu and Fan 2013] [Parachute injuries lessons 1997] [Sherer 1945] [Sulsky et al 2010] [Tharion et al 2025] [Westman and Äng 2015] [Westman and Äng 2016] [Whitting et al 2007] [Whitting et al 2007] [Whitting et al 2009] [Ye et al 2026] [Zhu et al 2024] [Zivkovic et al 2024]

The Apollo-Soyuz mission and the Soyuz record

The interim lifeboat’s own history. The Apollo-Soyuz mission reports and histories, and accounts of the Soyuz record.

21 records. [Apollo Soyuz Mission 5-Day 1975] [Apollo Soyuz test project 1974] [Apollo Soyuz test project 1975] [Apollo Soyuz, mission evaluation 1975] [Bean and Evans 1975] [Blackmer 1974] [Burnazyan 1979] [Ezell and Ezell 1978] [Frank 1976] [Froehlich 1978] [Lee 1975] [Lee 1977] [Lee and Lyman 1974] [Lindsay 2001] [Littleton 1975] [NASA Astronauts on Soyuz 2010] [Page and From 1977] [Petrone 1973] [Slayton 1974] [Soyuz-1 Conquers the Cosmos 1967] [Von Puttkamer 1975]

Sizing, mass estimation and scaling

The scaling argument. Sizing and mass estimation of entry vehicles and the square-cube law.

10 records. [Carichner 2013] [Collins and Hischke 1975] [Dutta et al 2012] [Guo et al 2016] [Johnson 1966] [Kuprikov 2021] [Kuprikov et al 2019] [Tauber 1970] [Tormo and Serghides 2007] [Wurster 1983]

Where the Framing Breaks Down

The Parafoil Numbers Rest on Two Assumed Coefficients

The lift coefficient of 0.80 and the glide ratio of 3 are typical values, assumed rather than taken from the flight results of the X-38 parafoil test programme [Madsen et al 2003]. The sizing section computes the sensitivity instead of asserting robustness, and the sink rate moves from 5.56 to 6.42 metres per second at a coefficient of 0.60 and to 4.97 at 1.00. The energy ratio moves only as the first power, between 19.7 and 32.8 across the same range, so the conclusion survives and the individual sink rates should not be quoted to three figures.

The Runway Comparison Uses a Speed the X-38 Never Had

Ninety metres per second is a touchdown speed taken from the X-24 family of lifting bodies and not from the X-38 [NASA account of the lifting bodies], which never landed on a runway and landed on skids rather than wheels [NASA account of the X-38 prototype crew return vehicle]. The comparison is therefore between this vehicle under its canopy and the vehicle it would have had to be if it landed on a runway. This comparison is the correct one for the argument, though it does not measure two things that both existed.

The Landing Opportunity Table Is an Order of Magnitude and Nothing Finer

The site counts are illustrative. Nobody has enumerated the world’s flat unobstructed areas, the reachability model treats sites as uniformly distributed over the covered band, and real site selection involves weather, overflight permission, recovery logistics and terrain. The direction survives, and so does the scale, a factor of thousands and not a factor of two.

The Reefing Conclusion Is an Inference From a Failure, and Its Margin Is Narrow

The article concludes that the canopy’s structure sets the stage count, and it concludes that because a vehicle-level load model fails to explain the flown system. The argument proceeds from the absence of an alternative and does not measure canopy loads, and a published analysis of this canopy’s line loads during inflation would settle it. The survey holds titles on this canopy’s deployment and on its aerodynamics at its opening stages [Ranier 2001] [Haubelt et al 2001] [Neville], and none of their titles names the line loads.

The margin is also narrower than the three g figure suggests. The full canopy reaches three g at 32.28 metres per second, which is only 1.20 times the assumed deployment speed, and it reaches two g at 26.36, which is below it. A deployment twenty percent faster than assumed, or a limit set at two g rather than three, would put the steady load back into contention, and the deployment speed is loosely reported. The encyclopaedia gives 60 miles per hour [NASA X-38] and the Dryden release about 70 [NASA’s X-38 crew rescue craft tests road to Earth], which is 31.29 metres per second and leaves a margin of only 1.03 times at three g.

The Scaling Comparison Puts Two Unlike Machines Side by Side

The X-24A was a piloted rocket research aircraft and the X-38 was a lifeboat designed for seven crew whose test vehicles flew under autonomous guidance [Martin Marietta X-24A] [NASA account of the X-38 prototype crew return vehicle]. Measuring an exponent between them is legitimate as a description and misleading as an explanation, and the article intends the first.

The exponent is also sensitive to figures that are easy to get wrong. It is computed from two published numbers for a vehicle retired in 1971 [NASA account of the lifting bodies]. Moving the X-24A length by half a metre moves the exponent by 0.79 to 1.39, and moving its mass by three hundred kilograms moves it by about a quarter. What is robust across the published figures is the sign, that mass grew faster than the cube of length, and the sign alone enters the argument. A length half a metre shorter than the shortest published figure would reverse it, at an exponent of 2.50.

Nothing Here Is Validated Against an Orbital Flight

No X-38 ever flew in space. Every entry number in this article is a calculation with no flight data behind it, and the vehicle that would have produced that data is held at the Johnson Space Center [NASA X-38]. An article about a vehicle that never flew its mission cannot verify the half of its argument that concerns the mission.

The Source Base

The Keystone Literature Is Not a Spacecraft Literature

The papers this article rests on are about canopies and most of them mention no vehicle at all. Of the 3,544 research records, 1,841 carry a decelerator term in their title, being parachute, parafoil, paraglider, parawing, decelerator, drogue, ballute, ram-air, canopy, reefing, airdrop or aerial delivery, and 1,772 of those name no spacecraft, entry, station, lifting body or crew return vehicle. A source base built from spacecraft vocabulary would have missed nearly the whole of it, which is the reason the selection here anchors on decelerator terms as heavily as on the programme.

Both Halves, Counted and Not Only Divided

Half Count Share of dated
The period and all that precedes it, through 2006 1,762 51.5 percent
Contemporary, 2007 onward 1,658 48.5 percent
Undated 124  
Total research records 3,544  

The period count is 1,762 and the contemporary count is 1,658. Both are given because a contemporary survey lowers the period share while leaving the period count untouched, so the share alone would understate the period literature. The median publication year is 2006. Every record of both halves is listed by subject in the cluster rows under The Contemporary Literature.

A date is not a measure of primacy and this article reports both. The technical report servers hold original research reports almost exclusively, while a journal index holds originals, reviews and comment together, so the report share is the closest available proxy for how much of the base is primary.

Measure Count Share
Technical reports, all eras 1,090 30.8 percent
Technical reports through 2006 777 21.9 percent
Journal and conference records 2,454 69.2 percent

A further 102 reference works are listed below, and they carry the relations that no journal article states because every textbook does. The count is the number of entries in that list.

The research survey holds 3,544 research records drawn from Crossref, the NASA Technical Reports Server and the Defense Technical Information Center, of which 1,090 are report primaries, being 30.8 percent, by the identifier rule set out under The Definition of Primary.

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. Primary sources in substance are the space agency and Army technical reports on decelerator systems, the programme’s own reports from 1995 to 2002, and the journal papers contemporary with each relation used.

The report literature matters for this subject. Of the 631 decelerator titles dated 2000 or earlier, 261 are report primaries by the identifier rule, being 41.4 percent, against 30.8 percent of the survey as a whole. The rule does not reach the journal and conference papers among the original sources, so 30.8 percent is a lower bound on how much of the survey is first-hand. A date and a primacy are different measurements and both are reported above, since a cutoff separates period from contemporary and says nothing about whether a record is an original report or a commentary on one.

Thin Subjects

The subjects an argument rests on are not the subjects its vocabulary names. This article displays relations drawn from the Allen and Eggers entry peak, the opening-shock factor, the square-cube law and the drogue sizing condition, and the literature those relations rest on is filed mostly under other words.

Eight 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 lift coefficient and glide ratio of a ram-air canopy parafoil, parafoils, ram air, paraglider, paragliders, parawing, parawings, gliding parachute, gliding parachutes together with lift coefficient, lift coefficients, glide ratio, lift to drag, lift and drag, lift drag 4
the flare of a parafoil parafoil, parafoils, ram air, paraglider, paragliders, parawing, parawings, gliding parachute, gliding parachutes together with flare, flaring, flared 3
reefing of a ram-air canopy parafoil, parafoils, ram air, paraglider, paragliders, parawing, parawings, gliding parachute, gliding parachutes together with reefing, reefed, slider, sliders, disreefing 7
the opening-shock factor opening shock factor, opening shock factors, opening load factor, opening force coefficient, opening force coefficients, inflation force coefficients, opening factor 8
the entry peak deceleration peak deceleration, maximum deceleration, deceleration loads, drag deceleration, Allen Eggers 3
crossrange crossrange, cross range 2
landing opportunities for a returning spacecraft landing opportunities, landing opportunity, deorbit opportunities, calldown, landing site coverage, landing site availability 3
the square-cube law and mass-length scaling square cube 3

The canopy lift coefficient is the article’s most load-bearing assumption, and its heading is thin while its subject is not. Four titles name a lift coefficient, a glide ratio or lift and drag for a gliding canopy, while the ram-air cluster holds 288 records, of which 35 are titled as aerodynamic characteristics, wind tunnel tests or flight tests. Those titles are where a measured coefficient would be reported, and a count of the heading alone could not have said so.

The flare is thin and the article’s flare result does not need it, since the energy identity derived above is exact within the steady-glide assumption, and three titles name the flare of a parafoil or parawing.

Reefing a ram-air canopy is mostly a slider literature. Of the seven titles, five name a slider, the device that reefs a sport or cargo canopy, and the staged inflation of the X-38’s own canopy is reported under the words opening stages and stages of inflation in the cluster on the X-38 and crew return vehicles.

The opening-shock factor is settled engineering that is recomputed for each system. Most of the eight titles that name it treat particular canopies, among them the Orion and Ares parachutes and ram-air airdrop canopies.

Some knowledge is settled and has stopped generating papers. The entry peak deceleration relation dates from 1958 and appears in every entry textbook, so its three records are not a gap.

Crossrange is almost absent as a title word. Two titles name it, and the lifting-entry literature reaches the subject through footprints and range control instead, with five titles naming a footprint and two naming range control.

The landing-opportunity argument rests on three titles, among them a report on Crew Return Vehicle deorbit opportunities, and the site counts in the article are illustrative for that reason.

The square-cube law has no spacecraft literature here. Its three titles concern airships, the aircraft industry and mechanical systems, so the exponent measured above rests on the two vehicles’ published dimensions alone.

And the last one is the article. Of the 66 titles that name the X-38, 62 date from 2006 or earlier and 2 from 2007 or later. The programme stopped in 2002 and the literature stopped with it.

What the Survey Admits

A record is admitted only when a person reading its title finds it on this article’s subject. The subject is the decelerator family, the vehicle and its lifting-body line, atmospheric entry and its protection, deorbit and the choice of landing place, the occupant’s tolerance of acceleration and of spaceflight deconditioning, landing impact attenuation, crew escape and spaceflight risk, the station the vehicle served, and the sizing of entry vehicles. Many words this subject depends on also name something else, and a record that shares only such a word is excluded. Parachute also names a heart valve, a surgical flap, a medical device, a pre-school game, a creek with an oil shale plant beside it, the children sent abroad to study alone and an executive’s severance, and reentry also names a prisoner’s return to the community and a cardiac arrhythmia. Drogue is also the French word for a drug and an ocean current marker, and a drogue in aerial refuelling is a different device. Reefing also names a surgical technique and reef a geological formation, opening force also names the force of a jaw, a spun fibre or a switch, and airdrop also names a distribution of cryptocurrency and a wireless file-sharing device.

Records that apply this subject’s constructs to a distant domain are excluded too. Clinical orthostatic intolerance in patient populations and its treatment, with no spaceflight or ground-analogue context, is excluded, and so are satellite and debris deorbit devices and uncontrolled reentry, missile tracking and reentry vehicle hardness, station subsystems, payloads and science, sports landing biomechanics, the crashworthiness of road and rail vehicles, and risk assessment of nuclear plants and other non-space systems. Correction, erratum, clarification and withdrawal notices, peer-review reports, reviews of books, news items, encyclopedia, dictionary and glossary entries that are unsigned or of two pages or fewer, patent abstracts and front matter are excluded as well, because a survey counts research works and those are parts of works or editorial events rather than works. A signed encyclopedia article and a textbook chapter are research works and stay, and so are a signed comment on a paper, an author’s reply to one and a signed letter on a research subject, because each argues about a result. Twin deposits of the same document are counted once.

Some records of doubtful relevance are kept. Crushable and energy-absorbing structures that name no vehicle, acceleration tolerance studies in animals, the aerodynamics and heating of ballistic missile reentry vehicles, Mars and lunar entry, descent and landing, aircraft ejection seats, the Apollo-Soyuz mission reports and plasma blackout during entry each share the physics, the structure or the occupant with this subject, so each is kept and a reader may weigh it accordingly. The two broadest clusters have stated rules. Parachute aerodynamics, stability and descent holds the parachute titles that name no inflation, recovery application, supersonic or planetary use, textile or gliding canopy, and entry vehicle aerodynamics, aerothermodynamics and design holds the entry titles that name no trajectory, guidance or thermal protection.

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.

What the Record Does Not Contain

No orbital flight data of any kind. No entry heating measurement, no orbital thermal protection performance, no deorbit accuracy, no orbital parafoil deployment. The vehicle that would have produced all of it was ninety percent complete when the programme stopped.

The Reference Works

Epistemic State

Historical Fact

The programme began at the Johnson Space Center in 1995 to demonstrate technology for a Crew Return Vehicle for the International Space Station. The aerodynamic shape was derived from the Martin Marietta X-24A. Scaled Composites built the atmospheric test airframes, and the European Space Agency and the German Aerospace Center took part in the programme. Three atmospheric vehicles flew, V-131, V-132 and V-131R, dropped from a B-52 at altitudes up to about 13,700 metres. In March 2000 V-132 flew freely for 44 or 45 seconds, by the two NASA accounts, after release at 11,900 metres and exceeded 800 kilometres per hour. The descent system used a 7,500 square foot ram-air parafoil, the largest ever made, deployed in five reefed stages. The orbital vehicle V-201 reached about 90 percent completion and never flew. The vehicle was designed for seven crew. The programme was cancelled on 29 April 2002.

Engineering Analysis

Every quantitative result here is computed from published dimensions and masses using standard relations. Three sensitivities are computed and none is asserted. They cover the lift coefficient through the sizing, the fixed mass fraction through the crew argument, and the deployment speed through the reefing argument. The first two leave their conclusions intact and the third narrows one. The glide speeds, the energy ratio, the wing loading, the area inversion, the deployment loads, the entry deceleration, the deorbit increment and the scaling exponents all follow from published figures. The identity that the flare’s available energy exceeds what it must remove by the square of the glide ratio is exact within the steady-glide assumption and carries no vehicle property at all.

Inference

That the canopy’s structure rather than crew tolerance sets the reefing stage count is an inference from a vehicle-level load model failing to explain the flown system by a wide margin. That abandoning the runway buys availability rather than costing capability is an inference from an order-of-magnitude landing-opportunity argument.

What the Record Does Not Settle

Whether the vehicle would have worked. No X-38 flew in space, no entry was ever demonstrated, no thermal protection system was exposed to orbital entry heating, and the parafoil was never deployed after an entry. The landing system was tested at nearly its design condition and the mission was not tested at all, and no amount of calculation closes that gap.

Out of Scope

The Soyuz as a lifeboat and its return system, which deserves separate treatment. The station’s assembly sequence and the crew-size decisions that drove the requirement. The detailed design of the deorbit propulsion module. The European crew transport studies that shared the programme’s structure work. The commercial crew vehicles that eventually solved the problem differently. Guided airdrop for cargo, which is surveyed here and not analysed.

Conclusion

The X-38 asked what a runway costs and answered it in one ratio. A lifting body arrives on a runway carrying 26.2 times the kinetic energy of the same mass under a ram-air canopy, and the ratio is the square of the speed ratio with the mass cancelling out entirely. All that the runway demands follows from that energy, namely the speed, the strip, the gear and the crossrange to reach one of the few places where all three exist.

Giving it up bought availability, the entire requirement of a lifeboat. A vehicle needing a certified runway gets a landing opportunity every ten days. A vehicle needing a flat field gets four hundred a day. The crossrange that the earlier lifting-entry articles of this series treated as a figure of merit turns out to have been the price of a decision, and the X-38 is the vehicle that declined to pay it.

The second answer is that the record-breaking canopy was an output rather than an ambition. Area varies as the inverse square of the sink rate, so wanting one metre per second less costs half as much canopy again, and seven seats aboard a station of seven fixed the mass. A single-seat version would still have needed 58.6 percent of the same canopy, because the airframe and the heat shield do not shrink with the crew.

Two smaller results stand out because neither needed an assumption. The flare’s available energy exceeds what it must remove by the square of the glide ratio, exactly, with no mass, area or density appearing, so a flare is never limited by energy. And the peak entry deceleration carries no ballistic coefficient at all, so the 3.87 g is fixed by the trajectory alone and the entry load a medical constraint rather than a structural one.

The third answer came from a calculation that failed. A vehicle-level load model predicts that the full canopy could have been inflated in one step inside three g, and the flown system used five stages. The constraint was never the crew. It is the canopy’s structure, and reefing exists to make a seven-hundred-square-metre inflation orderly rather than to make it gentle. The margin on that conclusion is only twenty percent in deployment speed, and three percent at the faster of the two reported speeds, which the article states and does not leave to be assumed.

What the programme did not answer is the half it was built for. The landing system was demonstrated within two percent of its design sink rate. The entry was never demonstrated at all, and the vehicle that would have demonstrated it was ninety percent complete when the station it was meant to serve shrank to a size its existing lifeboat could already carry. The X-38 was cancelled not because it failed but because the requirement went away, which explains why its record is thin.

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