X-Planes: X-58, the Slot Taken by XQ-58

The designation X-58 appears exactly once in a register of 539 allocations, inside a note about a different aeroplane, in a parenthesis, saying that it does not exist [Parsch, DOD 4120.15-L Addendum]. The register is the list of designations allocated since August 1998 that Andreas Parsch compiles from data the Department of Defense has released, and every count in this article is taken from all 539 rows of the copy he last updated on 23 August 2026. The note reads that the out-of-sequence number 58 of the Kratos Valkyrie was taken from the X-series, and that there is no X-58.

That copy is later than this article’s date. The version current on that date, the compiler’s update of 11 August 2025 as the Internet Archive captured it on 25 November 2025, held 526 rows, twenty-nine of them X rows, and lacked fifteen later rows that include the X-68A and the X-76A [Parsch, DOD 4120.15-L Addendum, 11 August 2025]. Its X numbers ended at 66, so the gaps between 44 and 66 were 52 and 58, the out-of-sequence Q numbers inside the X range were 42, 44 and 58, and 58 was the only one of them that was an X gap. Under that version 13 of the twenty-nine X rows, or 44.8 percent, described an unmanned aeroplane, 91 rows had no engine listed, and the series consumed 1.083 numbers a year over 24 years, giving about 861.2 years of headroom and about 11.1 months of allocation for one skipped number. The gap at 67 and the X-68A row that shows it became public only in a later update, so the parts of this article that rest on them describe the register after this article’s date. The X-58 note, the XQ-58A row and the absence of the Q symbol from every X row are the same in both versions.

This is the fifty-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, the X-37, the X-38, the X-39, the X-40, the X-41, the X-42, the X-43, the X-44, the X-45, the X-46, the X-47, the X-48, the X-49, the X-50, the X-51, the X-52, the X-53, the X-54, the X-55, the X-56, and the X-57.

The X-39 and the X-52 each reached this series as a number rather than as an aeroplane, and the X-58 is a third case with a third mechanism. The first was reserved and then lost because nobody wrote the letter that would have assigned it. The second was requested in writing, considered, and refused for resembling a number already in use [Missing USAF and DOD Aircraft Designations]. The X-58 was neither reserved nor refused. It was skipped, and the number was spent somewhere else while it was still the next one due [Missing USAF and DOD Aircraft Designations] [Parsch, DOD 4120.15-L Addendum].

The aeroplane that spent it is neither obscure nor small. The XQ-58A Valkyrie flew on 5 March 2019, two and a half years after its contract was awarded, and it has since been used by the United States Air Force to test technology for its future collaborative combat aircraft [Factsheet Technology, XQ-58A Valkyrie] [XQ-58A Valkyrie demonstrator completes inaugural flight] [Kratos XQ-58 Valkyrie]. The number 58 was not wasted. It was used, by a machine that used it hard.

What makes the case worth an article is that the aeroplane which took the number is arguably the most X-plane-like thing in the register, and it took the number by following a rule the X-planes break. That claim is measurable, the register is the instrument, and the sections below take the measurement rather than asserting it.

The Research Question

The X-58 had no research question, because there was never an X-58 to ask one. No vehicle was proposed under the number, no allocation letter for it is public, and the register mentions it only to say that it does not exist [Parsch, DOD 4120.15-L Addendum]. The question this article asks is therefore about a document rather than an aeroplane, namely why the number 58 was spent outside the X series while it was still the next one due.

The aeroplane that took the number had a different question, about money rather than aerodynamics. The Low Cost Attritable Aircraft Technology portfolio set out to break the escalating cost trajectory of tactically relevant aircraft, and the XQ-58A Valkyrie was its demonstrator [Factsheet Technology, XQ-58A Valkyrie]. Whether an aeroplane can be built cheaply enough to be lost and still be worth flying is the question that vehicle existed to settle, and the section on attritability below states it as an expected value.

The two questions are kept apart throughout. Every flight, figure and finding about the XQ-58A in this article is attributed to that vehicle and to its Q designation. None of it belongs to the X-58, which has no airframe, no flight and no data.

Programme Origin

The origin of this article’s subject is administrative, and it has two parts. The first is how the number 58 left the X series, which the register, the specialist registry and the governing instruction together fix in date and leave open in motive. The second is how the aeroplane that took the number came to exist, through a programme with a contract, a contractor and a first flight. The number is treated first and the aeroplane last, because the number is the anomaly and the aeroplane is only where it went.

What the Record Says Happened

There is no allocation letter in public and there is no stated reason. What exists is a register of allocations and a specialist registry’s reading of it, and the two together fix the event within a fortnight and leave the motive open.

The Valkyrie received the designation XQ-58A on 10 July 2017. The register records the allocation to Composite Engineering, with the United States Air Force as sponsor, an empty engines cell, and a mission statement reading that the aeroplane is an unmanned, transonic, long-range, low-cost, limited life, strike unmanned aircraft system [Parsch, DOD 4120.15-L Addendum].

The register’s contractor cell names a company that had been a subsidiary for five years. Composite Engineering Incorporated was acquired on 2 July 2012 and became part of the unmanned systems division of Kratos Defense and Security Solutions [Kratos Form 8-K, Acquisition of Composite Engineering, July 2012], and the same register names the same firm as the builder of the BQM-167 target drone [Kratos Defense and Security Solutions] [Kratos BQM-167 Skeeter] [Parsch, DOD 4120.15-L Addendum]. A register records the name that was on the request, not the name on the building.

The Evidence for Where the Number Came From Is Three Dates

The registry’s argument is chronological and it can be checked against the register itself. The three allocations in question are these.

Allocation	Designation	Contractor	Sponsor
03-May-16	X-57A	Empirical Systems Aerospace and Joby Aviation	National Aeronautics and Space Administration
10-Jul-17	XQ-58A	Composite Engineering	United States Air Force
21-Jun-18	X-59A	Lockheed Martin	National Aeronautics and Space Administration

The number 58 was allocated between the allocation of 57 and the allocation of 59, and the series in which 57 and 59 were allocated is the X series. No other evidence is offered, and the registry makes the argument in as many words [Kratos XQ-58 Valkyrie]. It is circumstantial and strong, because the alternative requires the number 58 to have been chosen by coincidence from a range that the Q series had not reached and would not reach for decades.

The X series has three gaps in its modern contiguous run and this is one of them. Counting the numbers the register carries between 44 and 68, exactly three are missing, and they are 52, 58 and 67. The X-52 was refused. The X-58 and the X-67 were taken by unmanned aircraft. Two of the three gaps in twenty-five consecutive numbers were made by the same mechanism six years apart [Parsch, DOD 4120.15-L Addendum] [Missing USAF and DOD Aircraft Designations].

The Registry States the Same Fact Four Times, at Four Different Confidences

One author, one website, one event, four statements, and the confidence is not the same in any two of them. The four are set out here because they show the difference between a record and a reading, and because an article that quotes only the most confident of the four would be quoting a selection.

Where	What it says	Its own hedge
The addendum note	the number was taken from the X-series	none, stated flatly
The missing-designations page	it is practically certain that the number was chosen to fit into the X-series	practically certain
The same page, under the Q series	the design number was apparently taken from the primary mission series	apparently
The vehicle page	it is unclear why the Valkyrie was designated XQ-58A instead of X-58A	unclear

The strongest statement and the weakest are about different questions, which resolves the tension between them. Where the number came from is asserted flatly. Why the letters are what they are is called unclear by the same author on the same site [Kratos XQ-58 Valkyrie] [Missing USAF and DOD Aircraft Designations]. The provenance of the digits is settled. The choice of the letters is not.

Nor does the registry treat this as a one-off. Under the Q series it records that the next available design number is 31, that the series has accumulated a number of out-of-sequence designations, and that in many of these the design number was apparently taken from the unmanned aircraft’s primary mission series. The two examples it gives are this aeroplane and the FQ-48 [Missing USAF and DOD Aircraft Designations].

Two Readings of the Letters, and a Wrong Number Under Both

The governing instruction is a public document and it settles more of this than the commentary does. The issue in force when the XQ-58A was allocated in 2017 and the X-59A in 2018 was Air Force Instruction 16-401 of 16 May 2014, which defines the designation and the process by which one is requested and approved [AFI 16-401, 16 May 2014]. Department of the Air Force Instruction 16-401, dated 3 November 2020, superseded it [DAFI 16-401], and each provision below is cited to the issue that carries it. The predecessors of both go back to 1962 and the earlier issues are also public [AFI 16-401].

A designation is built from six positions and the letter X occupies two of them. The order is status prefix, modified mission, basic mission, vehicle type, design number, series letter [Current Designations of U.S. Military Aircraft]. X is the status prefix for experimental and also the basic mission symbol for special research. The same letter, in adjacent positions, meaning two different things.

So XQ-58A has two possible parses, and the record leaves the intended one unstated.

• X as the status prefix. The designation is then an experimental aeroplane of vehicle type Q, with no mission symbol at all.
• X as the basic mission. The designation is then a special research aeroplane of vehicle type Q, which is well formed.

The instruction’s examples support the second parse in shape. For a non-standard aircraft the basic mission symbol appears immediately to the left of the vehicle type symbol, and the instruction gives LGM-118A, in which the basic mission G sits immediately left of the vehicle type M [DAFI 16-401]. XQ-58A has exactly that shape.

The sibling designations force the first. The register carries XRQ-72A and XRQ-73A, and in those the order of positions leaves no room for argument, because a basic mission symbol must sit immediately left of the vehicle type. In XRQ the letter beside Q is R, so X can only be the status prefix. The same is true of XMQ-17A, XMQ-19A and XRQ-22A [Parsch, DOD 4120.15-L Addendum]. Five members of the family read one way and this one is ambiguous.

The Instruction Requires a Mission Symbol at Its Highest Tier

Under the status prefix parse the designation is missing a required element. The instruction states that the vehicle type symbol is required for all non-standard aircraft and that a basic mission or modified mission symbol must accompany it, and marks the requirement T-0 [DAFI 16-401]. The 2014 issue in force at the allocation states the same requirement without a tier marking [AFI 16-401, 16 May 2014]. A T-0 requirement is one whose waiver authority sits outside the publishing organisation, the strongest tier the instruction uses [AFI 16-401].

The basic mission symbol is also required independently. The instruction calls it a required designator symbol for all standard and non-standard aircraft, and that it identifies the primary function and capability of the vehicle [DAFI 16-401].

Under the status prefix parse, therefore, XQ-58A carries a vehicle type and states no mission. The registry notes the same class of defect elsewhere, observing that YV-22A does not conform for the same reason [Current Designations of U.S. Military Aircraft]. This article does not assert that the Air Force intended the status prefix parse. It observes that one of the two available parses makes the designation non-conforming and that nothing in the record chooses between them.

The Design Number Is Scoped by One Letter and the Instruction Says Which

The instruction is explicit that each series has its own sequence. Each vehicle type and basic mission symbol forms a separate series of design numbers, and the numbers in each series are to be assigned in strict numerical sequence without reference to existing numbers in other series [Current Designations of U.S. Military Aircraft] [AFI 16-401, 16 May 2014] [DAFI 16-401].

The instruction also tells a requester how to find the right number. For a non-standard aircraft, the requester is to reference the basic mission and vehicle type designators, research the last approved design number of that combination, and determine the next in series from it [AFI 16-401, 16 May 2014] [DAFI 16-401]. The instruction contains the procedure that would have produced a Q-series number.

The register shows how far away from that number the allocation landed. The highest in-sequence Q number the register carries with a date on or before July 2017 is 27, so the number 58 sits 31 above it. The registry’s published figure for the next available Q number is 31, and that number is cited rather than derived here, because the addendum is a supplement and not a complete list and a naive scan of it reports a free number that is not free [Missing USAF and DOD Aircraft Designations].

And Then the Instruction Reserves the Right to Break Its Own Rule

One sub-paragraph after the sentence requiring consecutive numbering, the instruction grants the allocating office unlimited discretion to skip. The words are that the office reserves the authority to skip design number at discretion, and the 2014 issue in force at the time adds that skipped design numbers cannot be requested or used [AFI 16-401, 16 May 2014] [DAFI 16-401]. No criterion is given, no reason is required to be recorded, and no appeal is described.

That office is the same one that refused the X-52. Authority for designating and naming military aerospace vehicles is delegated to the Air Force Directorate of Programs, Program Integration Division, and the X-52 was refused by that office [AFI 16-401, 16 May 2014] [DAFI 16-401] [Allocation of Official Aerospace Vehicle MDS Designations] [Missing USAF and DOD Aircraft Designations].

The answer to the article’s opening question lies in administration and owes no part to aeronautics. The X-58 does not exist because a number was skipped by an authority that had reserved the power to skip numbers and was under no obligation to say why. The gap is neither a mistake nor a mystery. It is a discretion being exercised, and the instrument that records it records only the outcome.

The system has form for skipping in both directions, so the absence of a criterion matters. The registry records that numbers have several times been skipped in one series because they were in use in another, giving C-34 skipped to avoid confusion with T-34, and separately records that numbers have been carried across series boundaries, the production form of the X-35 having been designated F-35 when the next free F number was 24 [Current Designations of U.S. Military Aircraft]. The same system avoids a number for resembling another and copies a number for resembling another, and publishes no rule for either.

Every Obvious Explanation Fails Against the Register Itself

The natural guess is that the Valkyrie could not be an X-plane because it is unmanned, and the register refutes that guess without any help.

Half of the X Series Is Unmanned

Of the 31 X designation rows the register carries, 15 describe an aeroplane with nobody in it. That is 48.4 percent, just under half. The mission statements say unmanned, remotely piloted, autonomous or self-piloted in so many words [Parsch, DOD 4120.15-L Addendum].

They are not marginal entries. They include the X-45 and the X-47, which are armed unmanned combat air vehicles built to demonstrate the suppression of enemy air defences and carrier operation [Boeing X-45] [Northrop Grumman X-47B], the remotely piloted X-56, the X-61 Gremlins, a small unmanned aircraft launched and recovered in flight [Dynetics X-61 Gremlins], and the X-68A Longshot, whose register entry describes an experimental air-launched unmanned combat air vehicle for air-to-air engagements. The registry states the position plainly, that unmanned X-planes are quite common nowadays [Kratos XQ-58 Valkyrie].

Not One of Them Carries the Symbol the Instruction Requires

This measurement turns the article around. The instruction requires the vehicle type symbol for non-standard aircraft, and Q is the vehicle type symbol for an unmanned aerial vehicle [DAFI 16-401] [Current Designations of U.S. Military Aircraft]. The number of those 15 rows that carry the Q symbol is zero.

Fifteen unmanned aeroplanes are designated in the X series without the symbol the instruction requires, and one unmanned aeroplane carries the symbol and is designated in the Q series. It is also the aeroplane whose number the X series lost.

Read that way the anomaly inverts. The Valkyrie is not the aeroplane that failed to qualify as an X-plane. It is the aeroplane whose designation obeyed the vehicle type rule, and obeying it moved the aeroplane into a different series and took the number along. The fifteen that kept their X did so by omitting a required symbol.

This article does not claim that anybody reasoned that way in 2017. It claims that the register is consistent with it and inconsistent with the simpler explanations, and that the consistency is checkable by anybody who counts the rows.

The Mission Is Not the Difference Either

A second guess is that an X-plane researches and the Valkyrie fights. The register does not support that division. The X-45A’s mission statement is to demonstrate technical feasibility for an unmanned combat air vehicle to prosecute suppression of enemy air defences, and suppression of enemy air defences is precisely the role for which the Marine Corps intends the production Valkyrie [Parsch, DOD 4120.15-L Addendum] [Kratos XQ-58 Valkyrie] [Suppression of Enemy Air Defenses]. The same mission appears on both sides of the letter.

A third guess is armament, and the X-68A settles it. An experimental air-launched unmanned combat air vehicle for air-to-air engagements holds an X number, allocated in August 2025 [Parsch, DOD 4120.15-L Addendum]. Being armed is not what moved the Valkyrie out of the X series.

A fourth guess is the empty engines cell, and the cell means nothing. The XQ-58A row has no engine listed, and so do 94 of the register’s 539 rows, among them the X-59A and the X-60A, which plainly have engines [Parsch, DOD 4120.15-L Addendum]. The X-57 article sets out that measurement in full.

The Family of Borrowed Numbers

The Valkyrie is the first of a set and the set is now large enough to look at. Every Q number in the register that lies inside the range the X series occupies is listed below at its first allocation, with the registry’s account of where the number came from.

Designation	Allocated	Number	The registry’s account
YFQ-42A	Mar 2025	42	none given
YFQ-44A	Mar 2025	44	none given
YFQ-48A	20-Aug-25	48	apparently follows on from the F-47 in the F series
XQ-58A	10-Jul-17	58	taken from the X series, and there is no X-58
XQ-67A	19-Jul-23	67	taken from the X series
XRQ-72A	20-Mar-17	72	unclear where the number is derived from
XRQ-73A	12-Sep-23	73	out of sequence in both series, probably following the 72

Of the 7 such numbers, 4 are gaps in the X series and the remaining three are not. The four that are gaps are 58, 67, 72 and 73. The three that are not are 42, 44 and 48. The registry attributes 48 to the F series, and the attribution is consistent, because 48 is occupied in the X series by the Boeing blended wing body [Missing USAF and DOD Aircraft Designations] [Parsch, DOD 4120.15-L Addendum]. The number 44 is held by the X-44A, which the register carries, and 42 by the X-42A, allocated in late 1997 or early 1998 and so before the register’s window opens [Orbital Sciences USFE, X-42]. The registry gives no account of where the 42 and the 44 of the collaborative combat aircraft prototypes came from. The production FQ-42A and FQ-44A rows, dated June 2026, repeat those two numbers [Parsch, DOD 4120.15-L Addendum].

None of the out-of-sequence Q numbers in that range came from the Q series, and every one that is an X gap is accounted for. The registry’s summary is that the number was taken from the unmanned aircraft’s primary mission series, and the table is that sentence with dates attached [Missing USAF and DOD Aircraft Designations].

The registry has already written the obituary of a whole series on this ground. Of the fighters it records that the last sequentially assigned number was 23, that F-35 took its number from the X series, that a designation apparently exists for an undisclosed aircraft, and that there is, to all intents and purposes, no longer a sequence of F designations [Missing USAF and DOD Aircraft Designations]. The X-58 is what the beginning of that process looks like from inside.

What the Skip Cost

A skipped number sounds like a loss and the register can be asked how large a loss. The X rows span from 1999 to 2025, which is 26 years, and over that time the numbers run from 40, on the X-40B and X-44A rows of 1999, to 76 [Parsch, DOD 4120.15-L Addendum]. The lowest X number in the register is 37, on an X-37B row dated November 2006 that is a second model of a number whose first model the register does not carry, so it does not mark the start of the run. The rate at which the series consumes numbers is therefore the following.

\[\dot{d} \;=\; \frac{d_L - d_F}{t_L - t_F}\]

That evaluates to 1.385 numbers per year. The design number field runs to 999 before the instruction has to widen it, and the instruction says what happens then, which is that the range expands to 9999 [DAFI 16-401]. So the headroom and the price of a skip follow immediately.

\[t_{999} \;=\; \frac{999 - d_L}{\dot{d}} \qquad\text{and}\qquad \Delta t_s \;=\; \frac{1}{\dot{d}}\]

The sequence has about 666.6 years of numbers left at the present rate, and one skipped number costs about 8.7 months of allocation. What the X series lost by giving up 58 is eight or nine months of numbering out of six and a half centuries of supply.

The scarcity argument is therefore not available to either side. Nobody was short of numbers, so the skip cost nothing material, and by the same token nothing material was gained by taking one from a neighbour. Whatever the reason was, it was not arithmetic.

The Aeroplane That Took the Number

The Valkyrie exists because the Air Force Research Laboratory set out to break a cost curve rather than to advance a technology. The programme was the Low Cost Attritable Aircraft Technology portfolio, and its stated goal is to break the escalating cost trajectory of tactically relevant aircraft [Factsheet Technology, XQ-58A Valkyrie]. The goal concerns money, expressed in terms of aeroplanes.

The demonstrator inside it was the Low Cost Attritable Strike Demonstrator. A contract was awarded in 2016, Kratos offered a vehicle it called the XQ-222 which in some respects exceeded the requirement, the designation XQ-58A followed in 2017, and the aeroplane flew on 5 March 2019 at Yuma Proving Ground in Arizona [Kratos XQ-58 Valkyrie] [XQ-58A Valkyrie demonstrator completes inaugural flight] [Yuma Proving Ground].

Two and a half years from contract award to first flight is the number the laboratory chose to publish about itself. Its fact sheet states it twice [Factsheet Technology, XQ-58A Valkyrie].

The comparison with the article immediately before this one is not flattering to the X series. The X-57 was allocated its number in May 2016, fourteen months before the Valkyrie was allocated its own, ran until 2023, delivered an airframe, tested it on the ground, and closed out without ever leaving the runway [Parsch, DOD 4120.15-L Addendum] [X-57 Project Creates Paths Toward Electric Aviation]. The aeroplane that took the X series’ number flew in two and a half years. The aeroplane that kept the number before it never flew at all [Factsheet Technology, XQ-58A Valkyrie] [X-57 Project Creates Paths Toward Electric Aviation].

Sizing From First Principles

There was no X-58 to size. No vehicle was ever designed against the number, so no mass, thrust or geometry exists for it, and no record describes an intended aeroplane because none was intended.

What can be sized is the XQ-58A, and this article sizes it from its published figures rather than from any design document. The mass budget, the two published speeds and the design life that attritability implies are each worked from the specification the registry and the encyclopaedic account publish [Kratos XQ-58 Valkyrie] [Kratos XQ-58 Valkyrie]. These are reconstructions of a Q-series aeroplane and not of the X-58, and the registry’s specification note warns that its figures may be inaccurate [Kratos XQ-58 Valkyrie].

What It Is, in Numbers

The published figures are consistent across the registry and the encyclopaedic account, with one exception that matters and is dealt with below.

Quantity	Value
Length	9.1 m, being 30 ft
Wingspan	8.2 m, being 27 ft
Empty mass	1,134 kg, being 2,500 lb
Maximum mass	2,721.6 kg, being 6,000 lb
Payload	600 lb internal and 600 lb external
Thrust	8.9 kN, being 2,000 lbf
Cruise speed	476 kn, being 244.9 m per second
Maximum speed	Mach 0.85, quoted also as 566 kn
Service ceiling	45,000 ft, being 13,716 m
Range	3,000 nmi, being 5,556 km

The mass fractions follow from two of those rows and they are the first thing that tells you what kind of aeroplane this is. The budget closes in the usual way.

\[W_0 \;=\; W_e \;+\; W_p \;+\; W_f\] \[\zeta \;=\; \frac{W_f}{W_0} \;=\; 1 \;-\; \frac{W_e + W_p}{W_0}\]

The empty mass is 41.7 percent of the maximum and the fuel is 38.3 percent with both payload stations filled, which is 1,043.3 kg of fuel [Kratos XQ-58 Valkyrie] [Kratos XQ-58 Valkyrie]. The remaining six tenths of the maximum mass is useful load, and fuel takes nearly two thirds of it.

The payload fraction is the row that carries the comparison.

\[\Pi_p \;=\; \frac{W_p}{W_0}\]

The Valkyrie carries 20 percent of its maximum mass as payload. The X-46 measured the Boeing unmanned combat air vehicle family at 12.29 percent, and found the figure constant to three significant figures across a tripling of payload. The Valkyrie’s is 1.627 times that.

Two readings are available and the article does not choose between them. Either the aeroplane is genuinely more efficient at carrying things, which a structure relieved of a pilot, an ejection seat and a long life might well be, or the two figures are not measuring the same thing, because a fraction quoted against maximum mass and one quoted against a design gross weight differ by whatever fuel the design case leaves out. No source consulted here states which basis either figure uses.

The Two Published Speeds Do Not Refer to the Same Altitude

The specification table carries a maximum speed of 566 knots and a maximum Mach number of 0.85, and those two figures are not compatible at the altitude the aeroplane cruises at. The speed of sound depends only on temperature, and the temperature depends on altitude.

\[a_s \;=\; \sqrt{\gamma \, \mathcal{R} \, \Theta}\] \[M \;=\; \frac{V}{a_s} \;=\; \frac{V}{\sqrt{\gamma \, \mathcal{R} \, \Theta}}\]

At sea level the standard atmosphere gives 340.3 metres per second and at the quoted ceiling it gives 295.1 [U.S. Standard Atmosphere, 1976] [International Standard Atmosphere]. Evaluating the quoted speeds against both gives the following.

Quantity	At sea level	At 45,000 ft
566 kn as a Mach number	0.856	0.987
476 kn as a Mach number	0.72	0.83
Mach 0.85 as a speed in knots	562.3	487.5

The 566 knot figure is Mach 0.856 at sea level and Mach 0.987 at the ceiling. The first agrees with the published Mach 0.85 to within half a percent. The second is very nearly sonic and is not a speed a subsonic airframe of this shape holds.

So the two figures are consistent, and only at sea level. The sources are silent on this. A maximum speed quoted in knots and a maximum Mach number quoted beside it are the same limit expressed at two different altitudes, and a reader who assumes both apply at the ceiling will be wrong by fifteen percent.

The cruise figure behaves the same way and is less troublesome. At the ceiling, 476 knots is Mach 0.83, which sits below the maximum and is where a subsonic aeroplane of this planform would be expected to cruise. The cruise figure is therefore an altitude figure and the maximum is a sea level figure, a normal way to write a specification and an easy one to misread.

The dynamic pressure makes the difference concrete.

\[q \;=\; \tfrac{1}{2} \, \rho \, V^{2} \;=\; \tfrac{1}{2} \, \gamma \, p \, M^{2}\]

At 476 knots at the ceiling the dynamic pressure is 7.1 kilopascals. At 566 knots at sea level it is 51.9, which is 7.3 times as much. The structure is sized by the second and the mission is flown at the first, and the register’s mention of flight down to fifty feet means the second is not hypothetical [Kratos XQ-58 Valkyrie].

Attritability Is an Expected Value, Not an Attitude

The word the laboratory uses has a definition and the definition is quantitative. An attritable aircraft is one designed to be used for several missions but built at a cost that permits it to be a combat loss [Factsheet Technology, XQ-58A Valkyrie]. Several missions and a permissible loss are two numbers, and the design problem is the relation between them.

Let the per-sortie probability of surviving be $p$ and the design life be $N$ sorties. An airframe flies until it is lost or until its life expires, so the expected number of sorties one airframe delivers is a truncated geometric sum [Geometric distribution].

\[\bar{s} \;=\; \sum_{k=1}^{N} p^{\,k-1} \;=\; \frac{1 - p^{N}}{1 - p}\]

The limit as the design life grows without bound is the quantity that governs the design.

\[\lim_{N \to \infty} \bar{s} \;=\; \frac{1}{1-p}\]

Building a longer life than that gains nothing, because the aeroplane will not live to use it. With $p = 0.90$ the attrition-limited life is 10 sorties, with $p = 0.95$ it is 20, and with $p = 0.99$ it is 100. Those are hard ceilings set by the threat and not by the structure.

The design life should be matched to the survival probability rather than maximised.

\[N^{\star} \;\simeq\; \frac{1}{1-p} \qquad\text{and}\qquad \eta_L \;=\; \frac{\bar{s}}{N} \;=\; \frac{1-p^{N}}{N\,(1-p)}\]

Stated as a probability, the same result is starker.

\[\Pr\{\text{the airframe reaches } N\} \;=\; p^{N}\]

An airframe surviving nine sorties in ten reaches a life of ten with probability 0.3487 and a life of a hundred with probability 0.00002656. Qualifying a structure for a hundred sorties in that environment is qualifying it for an outcome that happens about once in forty thousand airframes.

The penalty for getting this wrong is severe and easy to state. An airframe given a life of 100 sorties and flown where $p = 0.90$ delivers 10 sorties, so 90 percent of the structural life that was paid for is never used. Given a life of 10 in the same environment it delivers 6.513 sorties, so the waste falls to 34.9 percent, and the article that is wasted is a much cheaper one. The attritable argument contains nothing beyond this, and it needs no doctrine.

The trade has been written down before and this article is not the first to make it. A systems conference paper works the reliability and cost implications of attritable design for unmanned aircraft directly, treating this section’s subject under this section’s name [Colombi et al 2017]. A design method paper does the same for the architecture question [Pagan et al 2018], and an earlier one sets out a design approach for low cost expendable unmanned systems seventeen years before the Valkyrie flew [Munro and Krus 2002].

The engine has a literature too, older than the airframe’s. The space agency built and tested a small low cost expendable turbojet in the nineteen seventies and reported its design and then its performance in two parts [Dengler and Macioce 1976] [Dengler and Macioce 1976], and the idea has been picked up again recently for this class of vehicle [Davidović et al 2025]. An attritable aeroplane needs an attritable engine, a separate problem with a separate history.

The exquisite aeroplane fails this test by construction. A structure qualified for thousands of hours, inspected on a schedule that assumes it will survive to need inspecting, and maintained to keep it airworthy for decades, is paying for a life the threat will not let it spend. The laboratory’s fact sheet makes the same argument about inspection and maintenance burden, in prose [Factsheet Technology, XQ-58A Valkyrie].

The Cost Per Sortie

Amortising the airframe over the sorties it is expected to deliver gives the figure a comparison can use.

\[\bar{C} \;=\; \frac{C_a}{\bar{s}} \;+\; C_{op} \;=\; \frac{C_a\,(1-p)}{1 - p^{N}} \;+\; C_{op}\]

Two unit costs are published and they assume different production rates. The airframe is stated to be producible at four million dollars each at fifty aircraft per year, and possibly under two million at more than a hundred per year [Kratos XQ-58 Valkyrie]. At a survival probability of 0.90 and a life long enough not to bind, the airframe cost per sortie is 400,011 dollars at the higher unit cost and 200,005 dollars at the lower. At 0.95 the same figures fall to 201,191 and 100,596 dollars.

Once the design life stops binding, that expression collapses to something with no free parameters at all.

\[\bar{C} \;\to\; C_a \, (1-p) \qquad\text{and}\qquad \frac{\partial \bar{C}}{\partial p} \;=\; -\, C_a\]

The cost per sortie becomes the unit cost multiplied by the probability of loss, and the derivative with respect to survivability is the unit cost itself. A single percentage point of survival probability is worth one percent of the airframe price, per sortie, at every value of the probability. At four million dollars that is 40,000 dollars a sortie and at two million it is 20,000.

That result explains the design philosophy in one line. Survivability is bought with money, and the amount it is worth is proportional to the price of the thing being made survivable. Making the aeroplane cheap does not merely reduce the loss when it happens. It reduces the value of preventing the loss, and therefore the amount worth spending on stealth, redundancy, warning receivers and everything else that makes an exquisite aeroplane exquisite.

The Comparison That Needs No Prices

No citable interceptor price is available, so the cost-imposing inequality below is left as a condition. The comparison against an aeroplane that is not meant to be lost has no such difficulty, because the absolute figures cancel.

\[C_a \, (1 - p) \;<\; C_x \, (1 - p_x) \qquad\Longrightarrow\qquad p^{\star} \;=\; 1 \;-\; \frac{C_x}{C_a} \, (1 - p_x)\]

Only the ratio of the two unit costs appears, and the price of neither is needed. Against an aeroplane twenty times its cost that survives 99 of every 100 sorties, the attritable aeroplane is cheaper per sortie whenever it survives more than 0.8 of its own.

Cost ratio	Against a survival of 0.99	Against a survival of 0.999
3	0.97	0.997
10	0.9	0.99
20	0.8	0.98
40	0.6	0.96

The table is the argument for attritable aircraft, stated without a single price. A cost ratio of forty buys the right to lose four sorties in ten and still be ahead of an aeroplane that hardly ever fails to come home. A cost ratio of ten against an opponent that is nearly invulnerable does not, since the attritable aeroplane must then survive 99 percent of its sorties, very nearly what the expensive one manages.

The First Row Is the One the Service Has Told Congress

The top row is not a round number chosen to fill a table. A congressional research product prepared for members and committees records that the Air Force has stated a collaborative combat aircraft would cost roughly one third the price of a crewed fighter [U.S. Air Force Collaborative Combat Aircraft, CRS IF12740, 15 August 2024] [U.S. Air Force Collaborative Combat Aircraft, CRS In Focus IF12740]. That is a cost ratio of three, the only official cost statement this article has found for the class the Valkyrie seeded.

At a ratio of three the aeroplane must survive 0.97 of its sorties to beat a crewed fighter that survives 0.99 of its own, and 0.997 to beat one that survives 0.999. Those are not attritable numbers. They are fighter numbers.

Set that beside the demonstrator’s published costs and the gap is the finding. At four million dollars against an eighty million dollar fighter the ratio is 20, and at two million it is 40. The demonstrator’s ratio is between six and thirteen times the one the service has stated for the programme it led to.

The eighty million dollar figure is an uncited assumption, used only to convert the demonstrator’s absolute price into a ratio for comparison. The ratio of three is quoted and the ratio of twenty is derived from an assumption, and the article keeps them apart on purpose.

The arithmetic shows that attritability does not survive a tenfold rise in unit cost. An aeroplane at a third the price of a fighter is a cheaper fighter, optimised the way a fighter is, because the value of every point of survivability has fallen only by a factor of three while the price of buying those points has not fallen at all. Whether that is what happened to this class is a question about a programme this article has placed out of scope, and the relation is displayed rather than the programme examined.

So the case does not depend on the aeroplane being cheap. It rests on the ratio being large and on the environment being hostile enough that the expensive aeroplane’s survival is not near one. In a permissive sky the arithmetic favours the exquisite aeroplane, and the laboratory’s fact sheet says as much when it observes that the most sophisticated unmanned aircraft are limited to permissive environments [Factsheet Technology, XQ-58A Valkyrie].

What a Cost Per Sortie Buys, in Airframes

A campaign needs sorties and a programme buys airframes, and the expected-sorties relation converts one into the other.

\[n_{ac} \;=\; \left\lceil \frac{S_{req}}{\bar{s}} \right\rceil\]

A thousand sorties at a survival probability of 0.90 needs 100 airframes, and at 0.95 it needs 51. Five percentage points of survivability halves the fleet. The derivative above gave the same result, here expressed in the unit a programme office orders in.

Those are airframe amortisation only and they exclude operating cost, weapons and everything else, so the relation above carries $C_{op}$ explicitly and this article does not fill it in. No published figure for the operating cost of this aeroplane was found.

The dependence on production rate is not incidental and it has a standard form. Unit cost falls with cumulative production along a learning curve, and the exponent is set by the progress ratio [Experience curve effects] [Roskam, Airplane design part VIII, airplane cost estimation].

\[C_u \;=\; C_1 \, u^{\,\beta}, \qquad \beta \;=\; \frac{\ln \phi}{\ln 2}\]

Solving the same relation for the progress ratio turns the two published costs into a testable claim.

\[\phi \;=\; \left( \frac{C_B}{C_A} \right)^{\!\!\frac{1}{\log_2 (u_B / u_A)}}\]

Read as a learning curve, the published pair implies a progress ratio of 0.5 and an exponent of -1. It halves unit cost for one doubling of output. Airframe learning curves are conventionally quoted between 80 and 85 percent [Roskam, Airplane design part VIII, airplane cost estimation] [Nicolai and Carichner, Fundamentals of aircraft and airship design] [Experience curve effects], and the number of doublings such a curve needs to halve a cost is not one.

\[\nu \;=\; \frac{\ln \tfrac{1}{2}}{\ln \phi}\]

On an 85 percent curve it takes 4.27 doublings to halve the unit cost. The same doubling that the published figures take from four million to two million would take an 85 percent curve to 3,400,000 dollars, and an 80 percent curve to 3,200,000.

The charitable reading is that the published pair is not a learning curve at all. The figures are quoted against annual production rates rather than cumulative units, and a rate is not a cumulative total [Kratos XQ-58 Valkyrie]. Read as rates the claim is about economies of scale, which are a different mechanism with different arithmetic, arising from tooling amortisation, purchasing and line balance rather than from repetition.

The article states both readings and settles neither, because no source consulted specifies the basis. What can be said is that under the reading the words most naturally support, the implied curve is far steeper than the ones the standard texts quote, and that this is the kind of claim a programme makes before it has built a hundred of anything.

The same mechanism explains why the two published unit costs differ by a factor of two, and why neither characterises the aeroplane. A cost that depends on a production rate that depends on a procurement decision is not a design parameter. The number two million dollars is a forecast conditional on somebody ordering a hundred aeroplanes a year, and no public record shows such an order.

The Cost-Imposing Claim, Left as a Condition

The fact sheet states an intent to force a cost-imposing effect on future adversaries [Factsheet Technology, XQ-58A Valkyrie]. The claim concerns an exchange ratio and has an exact form. If the defender expends $n_i$ interceptors of cost $C_i$ to remove one attacking aeroplane, the exchange favours the attacker when the following holds.

\[n_i \, C_i \;>\; \frac{C_a}{\bar{s}}\]

The comparison against a munition forms the other side of the same argument. An attritable aeroplane delivering $N_w$ weapons per sortie competes with a cruise missile of cost $C_m$ that delivers its effect once.

\[\frac{C_a}{\bar{s}\,N_w} \;+\; C_w \;<\; C_m\]

Why Survivability Is Expensive

The derivative above gives what survivability is worth. The radar range equation gives what it costs. Detection range against a given radar varies as the fourth root of the radar cross-section, because the returned power falls as the fourth power of range [Knott, Shaeffer and Tuley, Radar cross section].

\[R_d \;\propto\; \Sigma^{\,1/4} \qquad\Longrightarrow\qquad \frac{\Sigma'}{\Sigma} \;=\; \left( \frac{R_d'}{R_d} \right)^{\!4}\]

A fourth-root law is brutal in the direction the designer wants to go. Halving the range at which the vehicle is seen costs a factor of 16 in cross-section. Quartering it costs a factor of 256. A tenfold reduction in cross-section, a serious and expensive piece of engineering, leaves a detection range of 0.5623 of the original, removing rather less than half of it.

Put the two relations beside each other and the attritable case makes itself. Survivability is worth the unit cost per point, and its price follows a fourth-root law. Lowering the unit cost lowers the value of every point of survivability in exactly the proportion the price falls, while the price of buying those points does not fall at all. At some cost ratio the sums stop supporting the shaping, and the aeroplane is better made plainer, cheaper and more numerous.

This article does not claim to know where that point is for the Valkyrie, whose cross-section is not published and whose shaping is visible in photographs but not quantified in any source consulted.

One paper in the survey computes a cross-section for this aeroplane, and it could not use the aeroplane. It simulates a computer-aided design model that its title describes as Valkyrie-like [Max Chung and Tuan 2020]. When a study of an aircraft’s radar signature has to begin by building something that resembles it, the study shows how little is public, and the empty engines cell in the register shows the same. The relation is displayed because it is the mechanism, not because this article can evaluate it.

Both inequalities are left as conditions and neither is evaluated here, because this article has no citable figure for the cost of a modern surface-to-air interceptor or for the number expended per engagement. An inequality with one side unquantified describes structure and gives no result.

Dependent Systems

The X-58 has no dependent systems because it has no vehicle. The systems this section treats belong to the XQ-58A.

That aeroplane depends on three systems that a runway-based aeroplane would not need in the same form. It is launched from a trailer by solid propellant rocket boosters, recovered by parachute, and propelled by an engine whose class the sources dispute [Kratos XQ-58 Valkyrie] [Kratos XQ-58 Valkyrie]. None of the three is documented in detail anywhere consulted, so the booster impulse, the canopy size and staging, and the engine’s cruise thrust are derived as bounds and consistency checks rather than reported.

The range and the ceiling are treated here because both turn on the engine, the first through its specific fuel consumption and the second through the lapse of its thrust with altitude.

Leaving the Ground Without a Runway

Runway independence is a stated requirement and the register’s mission statement does not mention it. The vehicle is launched from a trailer using solid propellant rocket boosters and recovered by parachute, and the laboratory’s fact sheet names runway independence as offering maximum operational flexibility [Kratos XQ-58 Valkyrie] [Factsheet Technology, XQ-58A Valkyrie].

The wing area is not published, so the lift-off speed cannot be derived and is treated as a parameter throughout this section. The caveat is stated once here and holds for the rest of the section.

The booster has to supply the impulse the runway would have supplied. Along the launch rail the impulse balance is the following, with $T_e$ the engine thrust, $D$ the drag and $\mu F_N$ the rail friction.

\[\int_0^{t_b} T_b \, \mathrm{d}t \;=\; m \, V_{LO} \;-\; \int_0^{t_b} \left( T_e - D - \mu \, F_N \right) \mathrm{d}t\]

Discarding the engine contribution and the losses together gives an upper bound that is safe in the useful direction.

\[I_{req} \;\le\; m_0 \, V_{LO}\]

The propellant needed follows from the specific impulse [Specific impulse].

\[m_p \;=\; \frac{I_{req}}{g_0 \, I_{sp}}\]

Evaluated at the maximum mass and an assumed specific impulse of 230 seconds for the solid booster, the propellant required is small. The propellant varies inversely with the specific impulse, so a higher value only reduces the figures below.

Lift-off speed	Impulse required	Propellant	As a fraction of maximum mass
40 m per second	108,862 N s	48.3 kg	1.77 percent
50 m per second	136,078 N s	60.3 kg	2.22 percent
60 m per second	163,293 N s	72.4 kg	2.66 percent
70 m per second	190,509 N s	84.5 kg	3.1 percent

Two or three percent of the takeoff mass secures independence from every runway in the world. This section’s finding is a strong one, because the alternative costs an airfield, its defence and its position on a map. The trade is not close.

The rail is short as well. At a mean acceleration of five times gravity the length required follows directly.

\[L_r \;=\; \frac{V_{LO}^{2}}{2 \, a}\]

At a lift-off speed of 50 m per second that is 25.5 m, a length a trailer can carry.

Coming Back Without One

Recovery by parachute has to dispose of almost all of the energy the aeroplane has. The terminal velocity under a canopy of area $S_p$ and drag coefficient $C_{D_p}$ is the standard result [Knacke, Parachute recovery systems design manual].

\[V_t \;=\; \sqrt{\frac{2 \, W}{\rho \, C_{D_p} \, S_p}}\]

Solving for the canopy instead gives the size the recovery requires, since the canopy dimensions are not published either.

\[S_p \;=\; \frac{2 \, W}{\rho \, C_{D_p} \, V_t^{2}} \qquad\Longrightarrow\qquad D_p \;=\; \sqrt{\frac{4 \, S_p}{\pi}}\]

At the empty mass, sea level density and a canopy drag coefficient of 0.85, the requirement is as follows. The coefficient was measured in a wind tunnel for flat circular and extended-skirt recovery parachutes of an unmanned aircraft above six metres per second [Vu et al 2021].

Touchdown speed	Canopy area	Equivalent diameter
6 m per second	593.3 m squared	27.5 m
8 m per second	333.8 m squared	20.6 m
10 m per second	213.6 m squared	16.5 m

A canopy of twenty metres across for an aeroplane whose wings span eight is the price of not needing a runway at the other end. The area scales as the inverse square of the touchdown speed, so every metre per second of impact the airframe can tolerate is bought back several times over in canopy.

The Canopy That Lands It Cannot Be Opened at the Speed It Arrives

Everything above concerns the steady descent, the easy part. The sizing case is the opening, and writing it down shows that the two cannot be the same canopy.

\[F \;=\; k_s \, \tfrac{1}{2} \, \rho \, V_d^{2} \, C_{D_p} \, S_p\]

The shock factor is the term that carries the physics this expression leaves out, being the peak of the opening transient against the steady drag at the same speed, a quantity obtained by measurement [Knacke, Parachute recovery systems design manual] [Wolf and Fallon 2011].

Take the canopy that gives an eight metre per second touchdown, 333.8 square metres, and open it at 60 metres per second with no shock factor at all. The force is 625,624 newtons, which on the empty mass is 56.3 times gravity. No airframe of this kind takes that, and no payload does either.

The arithmetic is right and the premise is impossible, and that impossibility is the finding. A landing canopy opened at flight speed destroys what it is recovering. So the recovery must be staged, and the relation shows how.

One way out is to slow down first. Solving the same expression for the speed at which the full canopy is tolerable gives a limit.

\[V_d \;\le\; \sqrt{\frac{2 \, n_g \, m_e \, g_0}{\rho \, C_{D_p} \, S_p}}\]

The full canopy may be opened at 25.3 metres per second for ten times gravity and 17.9 for five. Those are speeds well below anything this aeroplane flies at, so something else has to take it from cruise to there.

The other way out is reefing, which opens a smaller canopy first [Knacke, Parachute recovery systems design manual].

\[\frac{S_r}{S_p} \;=\; \frac{2 \, n_g \, m_e \, g_0}{\rho \, C_{D_p} \, V_d^{2} \, S_p}\]

At 60 metres per second the first stage may present 59.3 square metres for ten times gravity, being 0.1778 of the full canopy, or 29.7 square metres for five, being 0.0889. This recovery therefore requires reefing to about a fifth of the full area.

The registry’s account states that the vehicle is recovered by parachute and goes no further. The staging is not documented anywhere consulted, and this section derives that there must be some rather than reporting what it is.

Where It Comes Down Is Not Where It Was Released

A slow descent is a long descent, and a long descent drifts.

\[x_d \;=\; V_w \, \frac{h_d}{V_t}\]

From a thousand metres at eight metres per second the descent lasts 125 seconds, and a ten metre per second wind carries the vehicle 1,250 metres downwind. Runway independence buys freedom from the airfield and pays for it in a recovery footprint over a kilometre across, which trades one constraint for another. The trade is real and has a cost, and the fact sheet’s phrase about maximum operational flexibility does not mention it [Factsheet Technology, XQ-58A Valkyrie].

The energy the recovery has to shed puts the scheme in proportion.

\[\frac{E_c}{E_t} \;=\; \frac{m_0}{m_e} \left( \frac{V}{V_t} \right)^{2}\]

The kinetic energy at cruise is 81.6 MJ and the kinetic energy at an eight metre per second touchdown is 0.036 MJ. The recovery sequence disposes of more than 99.9 percent of the aeroplane’s energy before the parachute is asked to do anything at all, and the parachute handles what is left. That work is done by the airframe decelerating aerodynamically, using the same drag the cruise section is trying to minimise.

Range, and a Disagreement the Arithmetic Can Settle

Two sources disagree about the engine and the disagreement matters. The registry’s specification table states one turbojet of 8.9 kN although its description names a single turbofan, and the encyclopaedic account states a Williams FJ33 turbofan of 2,000 lbf [Kratos XQ-58 Valkyrie] [Kratos XQ-58 Valkyrie] [Williams FJ33]. The thrust figures agree and the engine class does not. The laboratory’s fact sheet describes turbine inlet integration without naming the engine [Factsheet Technology, XQ-58A Valkyrie].

The distinction is not cosmetic, because the two classes have specific fuel consumptions that differ by roughly a third, and the range equation is sensitive to it [Mattingly, Heiser and Pratt, Aircraft engine design] [Anderson, Aircraft performance and design].

\[R \;=\; \frac{V}{c}\,\frac{L}{D}\,\ln\!\left(\frac{W_0}{W_1}\right)\]

Rearranged for the lift-to-drag ratio the published range demands, it becomes a test.

\[\left(\frac{L}{D}\right)_{\text{req}} \;=\; \frac{R\,c}{V\,\ln\!\left(\dfrac{W_0}{W_0 - W_f}\right)}\]

With the published range, the published cruise speed and the fuel fraction computed above, the product of speed over consumption and lift-to-drag must be 11,492,953 m. Evaluating at three plausible consumption figures gives the following.

Consumption assumed	Engine class it implies	Lift-to-drag the range requires
0.80 per hour	turbofan	10.43
0.90 per hour	turbofan	11.73
1.05 per hour	turbojet	13.69

A ratio near fourteen is a third higher than one near ten and a half, and it would have to come from a small swept airframe carrying an internal bay, which makes it the less likely of the two. The arithmetic therefore leans towards the turbofan, and it does so more strongly than the table shows, because the calculation charges the whole fuel load to cruise and allows nothing for climb, descent or reserve. Allowing for those raises every figure in the right-hand column and pushes the turbojet case further out of reach.

What the Engine Has to Do, and What That Costs

The lift-to-drag ratio the range demands can be turned round to say what the engine is doing in cruise.

\[T_{req} \;=\; \frac{W}{L/D}\]

At the mid-cruise weight and the derived lift-to-drag ratio the thrust required is 2,068 newtons, which is 0.2325 of the installed 8,896. An aeroplane cruising on less than a quarter of its sea level thrust is unremarkable, since thrust lapses with density and the remainder serves climb and acceleration.

The fuel flow and the endurance follow immediately.

\[\dot{W}_f \;=\; c \, T_{req} \qquad\text{and}\qquad t \;=\; \frac{W_f}{c \, T_{req}}\]

That gives 168.7 kilograms an hour and an endurance of 6.18 hours with every kilogram of fuel spent in cruise. Multiplying by the cruise speed returns 5,451 kilometres against the published 5,556. The two agree to within two percent, and the residual is the rounding in the lift-to-drag ratio and the use of a mid-cruise weight in place of the integral. A closure this tight gives the earlier argument about the engine class its weight, since a model that could not reproduce its input would be no evidence at all.

And It Partly Bounds the Operating Cost

The cost-per-sortie relation carries an operating term this article could not fill in. The numbers above determine one component of it, the fuel.

At 1,043.3 kilograms a sortie and an assumed dollar a kilogram, the fuel costs 1,043 dollars. The price is an assumption without a citation, stated so that the reader can substitute another and see that it does not matter. Against the airframe amortisation of 200,005 dollars at the lower unit cost and a survival probability of 0.90, the fuel is 0.522 percent.

A price ten times higher would still leave fuel under six percent of the amortisation. So the operating term is not where this aeroplane’s cost per sortie lives, and the unquantified part of the cost per sortie is narrower than it first appears. What remains unquantified is maintenance, ground equipment, the boosters, the parachutes and the people, and no public figure supports the fact sheet’s claim of low maintenance.

This is offered as a consistency argument and not as a resolution of the sources. No primary document consulted here names the engine. At most, the published range and the published fuel fraction are consistent with a turbofan and strained by a turbojet, and the registry cautions that its figures may be inaccurate [Kratos XQ-58 Valkyrie].

One assumption in that calculation deserves to be stated separately, because the answer moves a long way with it. The fuel load depends on whether the payload is aboard. With both stations filled the fuel is 1,043.3 kg and the required ratio is 10.43. With the internal station only it is 1,315.4 kg and 7.64. Clean, with no payload at all, the fuel is 1,587.6 kg and the required ratio falls to 5.76, which any aeroplane of this shape would meet easily. No source states which loading the 3,000 nautical mile figure assumes, and the range of answers spans a factor of nearly two.

The Ceiling, as a Second Opinion

A published ceiling is an independent constraint on the same aeroplane and it can be used as a check. At the ceiling the available thrust equals the drag, and thrust falls with density [Mattingly, Heiser and Pratt, Aircraft engine design].

\[T(h) \;=\; T_0 \, \sigma^{\,\kappa}, \qquad \sigma \;=\; \frac{\rho(h)}{\rho_0}\] \[T_0 \, \sigma^{\,\kappa} \;=\; D \;=\; \frac{W}{L/D} \qquad\Longrightarrow\qquad \left(\frac{L}{D}\right)_{\text{ceil}} \;=\; \frac{W}{T_0 \, \sigma^{\,\kappa}}\]

The density ratio comes from the standard atmosphere [U.S. Standard Atmosphere, 1976] [International Standard Atmosphere].

\[\sigma \;=\; \left(1 - \frac{\lambda h}{\Theta_0}\right)^{\frac{g}{\lambda \mathcal{R}} - 1} \qquad\text{and}\qquad \sigma \;=\; \sigma_{11} \, \exp\!\left(-\frac{g\,h}{\mathcal{R}\,\Theta_{11}}\right)\]

At 13,716 m the density ratio is 0.1936. Taking the sea level thrust as 8,896 N and the weight as that of the aeroplane with half its fuel gone, the lift-to-drag ratio needed to hold the quoted ceiling is 12.53 under a linear lapse, 9.02 under an exponent of 0.8 and 7.65 under an exponent of 0.7.

Those figures bracket the range calculation’s turbofan answers, though not its turbojet case, which justifies doing both. Two published quantities, arrived at by different routes and quoted by different sources, imply lift-to-drag ratios whose bands overlap between roughly ten and a half and twelve and a half. A specification whose range and whose ceiling disagree about the aeroplane would show it here, and this one does not.

The linear lapse is the pessimistic law and is shown first for that reason. A real installed turbofan at high subsonic Mach loses thrust more slowly than density, so the smaller exponents are given as well and no single figure is asserted.

The Flight Test Record

The X-58 has no flight test record, because nothing was ever built under that number. The register carries no X-58 row [Parsch, DOD 4120.15-L Addendum].

The flight record that exists belongs to the XQ-58A and is set out here under that vehicle’s name. The aeroplane first flew on 5 March 2019 at Yuma Proving Ground, two and a half years after its contract was awarded [XQ-58A Valkyrie demonstrator completes inaugural flight] [Factsheet Technology, XQ-58A Valkyrie]. What this article records is a sequence of events rather than of measurements, and it reports no flight-measured performance figure for the vehicle.

The Record of What It Has Done

The flight record is what keeps the designation question from being pedantic. The vehicle opened its internal bay and released a small air-launched vehicle in March 2021, has acted as a datalink relay between an F-35 and an F-22, was flown by an autonomy package developed under the Skyborg programme in 2023, flew in formation with an F-15E at Eglin in August 2023, and is the airframe on which the Air Force has developed its Collaborative Combat Aircraft concept [Kratos XQ-58 Valkyrie] [Kratos XQ-58 Valkyrie] [Skyborg] [Collaborative Combat Aircraft] [Anduril Altius] [Eglin Air Force Base].

The Marine Corps and the Navy each bought two, and the Marine Corps intends a production electronic attack variant designated MQ-58B [Kratos XQ-58 Valkyrie] [Kratos XQ-58 Valkyrie]. Note the letter. The production form drops the experimental status prefix and takes a modified mission symbol, as the instruction prescribes. The X series cannot do this, because a research designation has nowhere to go when the aeroplane stops being research [DAFI 16-401].

The observation is structural and may give the real reason. An aeroplane designated in the X series and then wanted in service has to change series to be procured, as the X-35 did when it became the F-35 [Current Designations of U.S. Military Aircraft]. An aeroplane designated XQ-58A becomes MQ-58B without changing series at all. The number survives the transition. A programme that expected to be procured had a reason to prefer a Q designation, and whether anybody thought of it is not recorded.

Comparison With Ground Prediction

For the X-58 there is nothing to compare. No prediction was made for a vehicle that was never proposed, and nothing flew, so flight returned nothing to set beside one.

For the XQ-58A the comparison cannot be made from the public record as this article reports it, and the article says so and supplies none. The figures it works with are published specifications, and it reports no flight-measured value of range, ceiling, speed, mass or lift-to-drag ratio against which to test them. The checks it does make compare one published figure with another, which tests the internal consistency of a specification and not the behaviour of an aeroplane in flight.

Those consistency checks are the nearest thing the article has to this section’s subject, and they are argued where they arise. Under Range, and a Disagreement the Arithmetic Can Settle, the article finds that the published range requires a lift-to-drag ratio of 10.43 at a consumption of 0.80 per hour and 13.69 at 1.05 per hour, and that its cruise model returns 5,451 kilometres against a published 5,556. The ceiling calculation finds that the quoted ceiling requires between 7.65 and 12.53. The two agree within the width of their assumptions. The comparison of the two published speeds finds that the 566 knot maximum agrees with Mach 0.85 at sea level and not at the ceiling.

Whether the aeroplane met its specification in flight is therefore not established here. The registry’s own specification note warns that its figures may be inaccurate [Kratos XQ-58 Valkyrie], and this article cites no flight result that confirms or corrects them.

What the Data Changed

No flight data exist for the X-58, so no flight changed anything about it. What changed the account of the X-58 was the register, read row by row.

The register’s counts changed the explanation. The guess that the Valkyrie could not be an X-plane because it is unmanned fails against 15 unmanned rows among 31 X designations, and the mission and armament guesses fail against the X-45A and the X-68A [Parsch, DOD 4120.15-L Addendum]. Each is set out under Every Obvious Explanation Fails Against the Register Itself. The same register shows two earlier places in the X series where a number became the right one, at the X-50A and the XRQ-72A.

For the XQ-58A the article records consequences and no measurements. The vehicle became the airframe on which the Air Force has developed its Collaborative Combat Aircraft concept, and the Marine Corps intends a production variant designated MQ-58B [Kratos XQ-58 Valkyrie] [Collaborative Combat Aircraft]. What those flights showed, in numbers, is not reported here, so the article cannot say which result moved which decision.

Symbols

Every symbol used in a display equation above is declared here, and every symbol declared here is used. Each symbol carries a single meaning throughout the article.

Symbol	Meaning
$\bar{s}$	expected number of sorties one airframe delivers
$N^{\star}$	design life matched to the survival probability
$N$	design life, in sorties
$k$	sortie index
$t$	time
$\gamma$	ratio of specific heats for air
$M$	Mach number
$a_s$	speed of sound
$\Theta$	air temperature
$q$	dynamic pressure
$\Pi_p$	payload fraction
$C_A$	unit cost at the lower production rate
$C_B$	unit cost at the higher production rate
$u_A$	the lower production rate
$u_B$	the higher production rate
$\nu$	doublings of output needed to halve the unit cost
$p^{\star}$	survival probability at which the two aeroplanes cost the same
$C_x$	unit cost of an aeroplane that is not meant to be lost
$p_x$	its probability of surviving one sortie
$n_{ac}$	airframes needed
$S_{req}$	sorties the campaign requires
$T_{req}$	thrust required in cruise
$\dot{W}_f$	rate at which fuel weight is consumed
$R_d$	range at which the vehicle is detected
$\Sigma$	radar cross-section
$n_g$	load factor the airframe may take on opening
$S_r$	reefed canopy area
$V_d$	speed at which the canopy is deployed
$V_w$	wind speed
$x_d$	distance the vehicle drifts under the canopy
$h_d$	height at which the descent begins
$k_s$	opening shock factor
$p$	probability of surviving one sortie
$\eta_L$	fraction of the design life actually used
$\bar{C}$	expected cost per sortie
$C_a$	unit cost of one airframe
$C_{op}$	operating cost of one sortie
$C_w$	cost of one weapon
$C_m$	cost of one cruise missile
$C_i$	cost of one interceptor
$n_i$	interceptors expended to remove one aeroplane
$N_w$	weapons delivered per sortie
$C_u$	cost of the unit numbered u
$C_1$	cost of the first unit
$u$	cumulative production unit number
$\beta$	learning curve exponent
$\phi$	progress ratio, the cost factor per doubling of output
$R$	range
$V$	true airspeed in cruise
$c$	thrust specific fuel consumption
$L$	lift
$D$	drag
$W$	weight
$W_0$	weight at the start of cruise
$W_1$	weight at the end of cruise
$W_f$	weight of the fuel
$W_e$	empty weight
$W_p$	payload weight
$\zeta$	fuel fraction
$T$	thrust available at altitude
$T_0$	sea level static thrust
$h$	geopotential altitude
$\sigma$	density ratio
$\sigma_{11}$	density ratio at the tropopause
$\rho$	air density
$\rho_0$	air density at sea level
$\kappa$	thrust lapse exponent
$\lambda$	temperature lapse rate in the troposphere
$\Theta_0$	air temperature at sea level
$\Theta_{11}$	air temperature at the tropopause
$g$	acceleration due to gravity
$g_0$	standard gravity
$\mathcal{R}$	specific gas constant for air
$T_b$	booster thrust
$t_b$	booster burn time
$T_e$	engine thrust during the launch run
$m$	mass
$m_0$	mass at launch
$m_e$	empty mass
$m_p$	booster propellant mass
$V_{LO}$	lift-off speed
$\mu$	coefficient of friction along the launch rail
$F_N$	normal force between the vehicle and the rail
$F$	force the canopy exerts as it opens
$I_{req}$	booster impulse required
$I_{sp}$	booster specific impulse
$L_r$	launch rail length
$a$	mean acceleration along the rail
$V_t$	steady descent speed under the canopy
$C_{D_p}$	canopy drag coefficient
$S_p$	canopy area
$D_p$	canopy equivalent diameter
$E_c$	kinetic energy in cruise
$E_t$	kinetic energy at touchdown
$\dot{d}$	rate at which the series consumes design numbers
$d_L$	highest design number allocated
$d_F$	design number of the earliest X allocation
$t_L$	date of the highest allocation
$t_F$	date of the earliest X allocation
$t_{999}$	time for the sequence to reach the end of its field
$\Delta t_s$	allocation time one skipped number costs

The Contemporary Literature

Cluster	Records
The aeroplane that took the number, and the programme that built it	1
Attritability, which is a design variable and not an attitude	16
What an aeroplane costs, and what makes it cost that	151
Fighting alongside a crewed aeroplane, which is what it is for	123
Autonomy, and letting the aeroplane decide	438
Attrition, exchange and the arithmetic of losing things	154
Surviving a defended sky, or not having to	167
Being a node rather than a platform	43
Leaving the ground without a runway, and coming back without one	218
Range, endurance and the fuel it takes	160
Sizing the aeroplane around the constraint	44
Unmanned airframes and their aerodynamics, the combat configurations above all	94
Flight control, guidance and navigation without a pilot	162
Unmanned aircraft in doctrine, programmes, operations and history	87
The people who fly unmanned aircraft from the ground	32
The atmosphere and the flight condition	36
Unmanned aircraft engineering in general	140
Total	2,066

2,066 research records map the field this aeroplane sits in, across 17 clusters. Every row states a count over the reference list, every record sits in exactly one row, and the counts sum to the total.

The aeroplane that took the number, and the programme that built it

The smallest cluster that is squarely about the subject is the one naming the aeroplane itself, which is what a survey of a recent demonstrator looks like. The cluster holds 1 record.

1 record. [Max Chung and Tuan 2020]

Attritability, which is a design variable and not an attitude

This is the keystone cluster and it is the second smallest in the survey, which is a finding rather than a defect and is treated as one in the section headed The Source Base. Its titles name an attritable, expendable or low-cost expendable aircraft, engine or system, or the trade between survivability and numbers. The cluster holds 16 records.

16 records. [Colombi et al 2017] [Cybenko and Hallman 2021] [Davidović et al 2025] [Dengler and Macioce 1976] [Dengler and Macioce 1976] [Hawkins 1989] [Huben and Metsker 1978] [Jeffcoat 2003] [Jeong and Oh 2026] [Jones et al 2021] [Kahn and Edwards 2015] [Lilley et al 1991] [Ma et al 2021] [Miller 2024] [Munro and Krus 2002] [Pagan et al 2018]

6 of the 16 titles use the word attritable, and the earliest of them dates from 2017. Of the eight earlier titles, seven say expendable instead, and the oldest, from 1976, concern a small expendable turbojet engine.

What an aeroplane costs, and what makes it cost that

The cost literature is where the concept actually lives, under words the programme does not use. It holds cost estimating, unit and life-cycle cost, design to cost, cost-effectiveness and affordability for aircraft, weapons and defence acquisition, low-cost designs of unmanned aircraft, and the learning curve in any industry, because the article applies it. The cluster holds 151 records.

151 records. [Adams and Hinders 1974] [Agez 2024] [Analysis of the relationship 2024] [Anderson et al 1973] [Anderson and Dixon 1975] [Apgar 1993] [Arifianto and Farhood 2014] [Ascani et al 1980] [Badiru 1991] [Badiru 1992] [Badiru and Jaber 2026] [Barclay et al 1993] [Bateman et al 2007] [Battelle Columbus Div Oh 1988] [Bell 1993] [Beltramo 1993] [Bennett 1990] [Bernstein 1994] [Biegel and Bulcha 1977] [Boudreau 2005] [Boudreau 2006] [Brannon 1976] [Broden and Gilles 2001] [Butler 1979] [Campbell 1981] [Carleton 1979] [Carlyle 1976] [Chamis 1983] [Chen and Storch 2013] [Cherry 1975] [Cho and Seeger 1981] [Cody and Tiedje 1997] [Collins 1975] [Cork 1979] [Cost-Estimating Relationships for Aircraft 1972] [Cunningham 1980] [Curran et al 2008] [Dance and Jarvis] [Dehm and Patrakis 1982] [Department Of Defense Washington Dc 1970] [Department Of Defense Washington Dc 1970] [Detweiler 1995] [Detz and van der Zwaan 2020] [Developing a forecasting model 2009] [Di Pietro 2015] [Dorsett 1989] [Eijsink and Rice 1978] [El-Sayed 2024] [Etesse 1979] [Etherington 1985] [Etherington 1988] [Factors that influence Manufacturing] [Fellers and Patierno 1970] [Ferraiolo 1978] [Fluk 1981] [Flynn 2013] [Forville 1977] [Fox 1965] [Franceschini and Galetto 2004] [Gansler et al 2010] [Gille et al 1990] [Gille and Warren H. 1992] [Goclowski and Baran 1980] [Gold 1973] [Górski et al 2022] [Greer 2010] [Gregory and Wilcox 1970] [Hamilton and Ochmanek 2020] [Hampton 1984] [Hartley 1965] [Haynes 2008] [Hays et al 1975] [Herd et al 1965] [Himpler 1975] [Hogan et al 2020] [Hogan et al 2022] [Hong et al 2020] [Houseman et al 2008] [Irfan bin Edi et al 2022] [James and Stein 1978] [Johnson 1969] [Johnson 1990] [Jones 2018] [Jun 2024] [Kangaspunta and Salo 2013] [Keller 1982] [Kihlman et al 2004] [Klimowitch 1978] [Krings et al 2013] [Krupnik 2022] [Learning Curves Production Breaks/Lost 2015] [Learning Curves Production Breaks/Lost 2026] [Life Cycle Cost 2010] [Lin et al 2011] [Logistics Management Inst Bethesda Md 1965] [Logistics Management Inst Bethesda Md 1967] [Lovelace 1998] [Low Cost Cargo Aircraft 1960] [Lu et al 2015] [Majd and Pindyck 1987] [Manufacturing cost estimation A 1993] [Marx et al 1995] [Mazzola and McCardle 1997] [McClure 1977] [Morimoto et al 2015] [Moses 1990] [Moses 1991] [Moses 1991] [Moses 1992] [Moses 1995] [Nemet 2006] [Nussbaum 1994] [Osterbeck et al 1979] [Otto and Thomas W. 1975] [Owens et al 2006] [Palazzo and Rosenfeld 1983] [Parametric Flyaway Cost Estimating 2024] [Pettigrew 1983] [Pohya et al 2018] [Pokorny 2026] [Product Life Cycle Cost] [Pulley 1977] [Rebikoff] [Laracy and Marlowe 2019] [Rorsted 1999] [Rosales and Gross 2017] [Roussos et al 2025] [Schaffner et al 2013] [Shimpi and Sawarkar 2026] [Simpson et al 2003] [Smunt 1999] [Smunt 2000] [Smunt 2011] [Sterk et al 2016] [Sun et al 2022] [Tan et al 2012] [Teufel et al 2003] [Thokala et al 2012] [Tierney et al 2021] [Tilley et al] [Tirkel 2013] [Trigg 1973] [Tsuchiya 1990] [Tsuchiya 2004] [Using the Learning Curve 2010] [Wang et al 2018] [Watson Jr. 2003] [Weimer 1977] [Wu et al 2022] [Yao et al 2021] [Young et al 2022]

40 of the 151 titles name a learning or experience curve, and 32 name a life-cycle cost or the cost of ownership. The learning curve is evaluated against the two published unit costs in the section headed What a Cost Per Sortie Buys, in Airframes.

Fighting alongside a crewed aeroplane, which is what it is for

Teaming is the role the airframe has flown since its demonstration, and the literature is recent. It holds crewed and uncrewed teaming, loyal wingman studies, the supervisory control of several unmanned vehicles by one crew, and the human factors of both. The cluster holds 123 records.

123 records. [Albawaneh et al 2025] [Andrews et al 2020] [Andrews et al 2020] [Arthur 2008] [Athanasiadou et al 2026] [Bailey 2008] [Bajpai et al 2025] [Banas et al 2020] [Bao et al 2026] [Calhoun et al 2017] [Calhoun et al 2012] [Catak et al 2025] [Chen and Barnes 2013] [Chen et al 2026] [Chen et al 2026] [Choi et al 2026] [Clare et al 2012] [Dantas et al 2024] [Das et al 2017] [Ding et al 2026] [Donkels and Voigt 2019] [Donmez et al 2009] [Donmez and Cummings 2010] [Draper 2008] [Driggs et al 2026] [Dudek and Schulte 2022] [Durbin and Hicks 2009] [Evaluating The Use of 2015] [Faisal and James 2025] [Fan et al 2017] [Flaherty et al 2006] [Flores et al 2025] [Formation and adjustment of 2018] [Friedrich et al 2022] [Friedrich and Schulte 2025] [Friedrich and Vollrath 2022] [Frontera Sánchez] [Gangl et al 2013] [Giacomossi et al 2021] [Gozzi and Schulte 2026] [Hammarbäck 2022] [Hammarbäck et al 2023] [Han et al 2025] [Heilemann and Hollatz 2020] [Hicks et al 2009] [Hicks and Durbin 2014] [Hoke 2018] [Hong and Baek 2025] [Humphreys et al 2015] [Humphreys et al 2016] [Humphreys et al 2017] [Hwang and Han 2025] [Hwang et al 2022] [Jeong 2026] [Jeong et al 2026] [Jia et al 2016] [Jung et al 2025] [Kiam et al 2022] [Kilgore et al 2009] [Kim 2026] [Kim and Kim 2026] [Kim and Lee 2022] [Kohn 2022] [Korecki and Hoika 2026] [Künzel et al 2025] [Langen et al 2023] [Lee and Jeong 2025] [Lee and Kang 2025] [Lee et al 2025] [Lee and Na 2023] [Lee and Park 2024] [Lee et al 2025] [Levulis et al 2018] [Lewkowicz 2026] [Lyons et al 2021] [Maier et al 2024] [Malhotra et al 2024] [Martin and Esteban 2025] [Matsuno and Andreeva-Mori 2023] [Mekdeci and Cummings 2009] [Meyer and Schulte 2020] [Meyer and Schulte 2022] [Michelson and Domercant 2019] [Nelson et al 2006] [Park et al 2022] [Paul et al 2025] [Pericon 2024] [Prasetiyo et al 2024] [Qi and Xie 2026] [Roltgen and Gilbert 2010] [Roncolini and Quaranta 2024] [Rosenblum et al 2022] [Roth et al 2020] [Roth and Schulte 2020] [Roth and Schulte 2022] [Roth and Schulte 2022] [Ruf and Stütz 2016] [Ruf and Stütz 2018] [Sadraey 2018] [Sadraey 2025] [Schmitt and Schulte 2015] [Schmitt and Schulte 2015] [Schwerd and Schulte 2021] [Shively et al 2011] [Sparrow and Henschke 2023] [Sperling et al 2008] [Stewart et al 2012] [Strenzke et al 2011] [The People’s Liberation Army’s 2025] [Tierney et al 2005] [Uybarreta et al 2025] [Voigt et al 2019] [Wade 2021] [Wang et al 2023] [Wright et al 2022] [Wright et al 2024] [Wu et al 2019] [Wuwer et al 2025] [Yang et al 2024] [Yin et al 2020] [Yoo et al 2021] [Yuan et al 2025] [Zhang et al 2024]

80 of its 122 dated records were published in 2020 or later, and its median publication year, 2022, is the latest of any cluster, shared with the autonomy cluster.

Autonomy, and letting the aeroplane decide

The largest cluster in the survey, and most of it postdates the allocation of the number. It holds autonomous flight and mission management, path planning, cooperative control, task allocation and swarms of unmanned aircraft, and machine decision making in air combat. The cluster holds 438 records.

438 records. [Akash and Anbarasu 2025] [Alabbadi and Sababha 2023] [Alamdar et al 2026] [Alighanbari and How] [Allen 2006] [Allen 2007] [Allen 2007] [Alsayed et al 2022] [Anowar et al 2026] [Aweiss et al] [Ashokaraj 2005] [Ashokkumar 2023] [Aslan and Erkin 2023] [Aslan and Oktay 2023] [Automation and Autonomy in 2016] [Autonomous Control of Unmanned 2019] [Ananyev 2019] [Bae et al 2023] [Baek and York 2020] [Bakker and Klenke 2014] [Bakos and Davoudi 2022] [Barlow 2004] [Barnhart 2012] [Baspinar and Koyuncu 2018] [Baykal and Baspinar 2023] [Bayraktar et al 2004] [Bayraktar et al 2004] [Benders 2018] [Benders et al 2018] [Ben Ludington 2006] [Bildik et al 2024] [Blidberg 2003] [Braasch 2006] [Brinker 2004] [Brown and Sun 2017] [Burkhard and Clark 2015] [Cao et al 2023] [Castanon and Cassandras 2010] [Cetin and Yilmaz 2014] [Chai et al 2023] [Chakravarthy and Ghose 2020] [Chamitoff 1994] [Chamitoff 1995] [Chang et al 2022] [Changyou Liu and Ningquan Luo] [Chen et al 2026] [Chen et al 2002] [Chen and Duan 2024] [Chen et al 2024] [Chen and Hu 2012] [Chen et al 2026] [Chen et al 2025] [Chen et al 2025] [Chepizhenko et al 2023] [Chichka 2008] [Chin et al 2016] [Chin et al 2016] [Chitrakaran et al 2006] [Civelek and Kıvrak 2024] [Clough] [Control of cooperative unmanned] [Cooper et al 2018] [Corban et al 2004] [Costa and Ogren 2025] [Costa et al 2023] [Cox 2009] [Cui and Yang 2021] [Cui et al 2022] [Dam] [Damien 2009] [Dang et al 2023] [Dantas et al 2023] [Dawkins et al 2018] [De Alba et al 2024] [del Ser et al 2024] [Deming and Perlovsky] [Design, control, and autonomous] [de Vries and Subbarao 2011] [Ding] [Ding et al 2025] [Ding et al 2026] [Diyachuk and Chekareva 2025] [Dobrokhodov 2011] [Doherty et al] [Doherty et al 2009] [Dong and Ai 2012] [Dong et al 2015] [Dong Kangsheng et al 2016] [Dufrene 2004] [Duraklar 2024] [El-Fiqi et al 2020] [Ernest and Carroll 2016] [Ernest and Cohen 2016] [Eun and Bang 2004] [Eun and Bang 2006] [Fan et al 2024] [Fane Kong et al 2008] [Farmani et al 2015] [Feng et al 2023] [Fernando et al 2019] [Fields et al 2011] [Figueiredo Prudencio] [Fu and Yang 2026] [Fu Li et al 2008] [Gao and Pan 2024] [Gao et al 2024] [Garcia and Casbeer 2017] [Gavin and Bronz 2026] [Gavin et al 2024] [Ghosh et al 2025] [Gong et al 2022] [Guijarro Reyes et al 2018] [Guo et al 2026] [Guo and Zhu 2024] [Gupta et al 2022] [Ha and Choi 2026] [Hafez et al 2015] [Hafez and Kamel 2016] [Han et al 2019] [Han et al 2020] [Han et al 2022] [Han et al 2025] [Hao et al 2026] [Hartman 2019] [Hashim 2020] [He et al 2024] [He et al 2024] [Hewett 1991] [Hirsch and Schroeder 2014] [Hong et al 2022] [Horowitz et al 2014] [Hou et al 2019] [Hovakimyan 2009] [Hu et al 2024] [Hu et al 2023] [Hu et al 2022] [Hu et al 2022] [Hu et al 2026] [Hu et al 2021] [Huang 2025] [Huang et al 2024] [Huang et al 2019] [Huang et al 2017] [Huang et al 2018] [Huhn et al 2009] [Huo et al 2025] [In-flight demo of multiple 2007] [Iqbal et al 2026] [İşci and Günel 2021] [Isci and Koyuncu 2022] [Jain et al 2017] [Ji et al 2024] [Jia et al 2023] [Jian et al 2024] [Jiandong et al 2021] [Jiang et al 2026] [Jianhong and Gongqian 2025] [Jin et al 2022] [Jones and Dye 2016] [Joyce 2026] [Jun and D’Andrea 2003] [Kallstrom and Heintz 2020] [Karimoddini et al 2022] [Keles et al 2025] [Kelner and Ziółkowski 2020] [Keshmiri et al 2018] [Khatiwada et al 2018] [Kim and Bang 2016] [Kim et al 2015] [Kim et al 2015] [Kim and Morrison 2018] [Kim and Morrison 2019] [Kim et al 2017] [Kladis et al 2011] [Klesh et al 2009] [Kocaman 2026] [Kong et al 2020] [Kong et al 2020] [Kong et al 2020] [Kong et al 2022] [Kong et al 2023] [Wu and Litt 2023] [Kurnaz et al] [Kurniawan et al 2019] [Lalitha et al 2023] [Lee and Kim 2020] [Lee et al 2017] [Leonard et al 2012] [Leonard et al 2013] [Leylek and Costello 2010] [Li et al 2022] [Li et al 2025] [Li et al 2020] [Li et al 2022] [Li et al 2022] [Li et al 2022] [Li et al 2025] [Li et al 2026] [Li et al 2024] [Li et al 2025] [Li et al 2022] [Li et al 2025] [Li et al 2022] [Li et al 2019] [Li et al 2023] [Li et al 2024] [Li et al 2024] [Liang 2008] [Liang 2010] [Liang et al 2014] [Liang et al 2024] [Liang et al 2022] [Lima Filho et al 2021] [Lin 2002] [Lin et al 2023] [Lin et al 2024] [Lindsay and Sun 2020] [Linne 2022] [Liu et al 2021] [Liu et al 2025] [Liu et al 2019] [Liu et al 2024] [Liu et al 2026] [Liu et al 2023] [Liu et al 2024] [Liu et al 2024] [Liu et al 2024] [Liu et al 2026] [Liu et al 2024] [Liu and Ma 2017] [Liu et al 2020] [Liu et al 2023] [Liu et al 2023] [Liu et al 2020] [Liu et al 2022] [Liu et al 2026] [Liu et al 2024] [Lizzio et al 2021] [Lunsford and Bradley 2025] [Luo et al 2025] [Lyshevski 2018] [Ma et al 2020] [Mammadov and Gueaieb 2014] [Manoharan et al 2023] [Matlock et al 2009] [Maughan et al 2015] [McGee and Hedrick 2006] [McKinnis et al 2021] [Mei et al 2024] [Miller 2006] [Minglang et al 2018] [Mobile Autonomous Recovery Landing 2024] [Morris et al 2005] [Moudgil et al 2026] [Mu et al 2026] [Mukherjee] [Nagy and Laufer 2024] [Navickiene et al 2025] [Neubauer et al 2022] [Neubauer et al 2023] [Neubauer et al 2023] [Nguyen et al 2024] [Orhan et al 2026] [O’Rourke et al 1999] [Pack et al] [Pack and York 2008] [Pan et al 2020] [Path Planning for Multiple 2010] [Vajda and Maris 2021] [Peng et al 2022] [Peng Teng et al 2008] [Pierron and Lahire] [Pinon et al 2022] [Pope et al 2021] [Pope et al 2023] [Powell 2001] [Primatesta et al 2021] [Qian et al 2025] [Radmanesh et al 2018] [Ragi and Chong 2013] [Rahman et al 2026] [Ramírez López and Żbikowski 2018] [Rasmussen and Schumacher 2007] [Ren et al 2023] [Roberts and Ferrazano 2004] [Ronchieri and Innocenti 2007] [Rosaldo-Serrano et al 2017] [Rosenfeld and Davis 1986] [Ru and Subbarao 2017] [Ruff and Calhoun 2013] [Safe Coordinated Maneuvering of 2016] [Saif et al 2014] [Salhi et al 2026] [Samiei and Sun 2020] [Scheidt 2014] [Schopferer and Pfeifer 2015] [Schosser et al 2026] [Sease et al 2023] [Selmonaj et al 2026] [Selmonaj et al 2025] [Selmonaj et al 2023] [Shanshan et al 2020] [Sharma et al 2012] [Sharma and Pack 2013] [Sherstjuk et al 2019] [Shima et al 2014] [Shiyou et al 2011] [Shkarayev 2009] [Shmelova et al 2025] [Shumway and Beard 2025] [Singh and Kamal 2025] [Smith] [Smith and Schnell 2026] [Sobers et al 2010] [Song et al 2026] [Soykan and Koksalmis 2026] [Subbarao and Ru 2017] [Sun et al 2024] [Sun et al 2026] [Surka 2001] [Survivability of Unmanned Autonomous 2016] [Tachinina et al 2017] [Tan et al 2018] [Tan et al 2024] [Tan et al 2024] [Tan et al 2022] [Tang et al 2026] [Taranto and Abdulrahim 2023] [Taşbaş et al 2023] [Teague et al 2008] [Tekinalp and Ariyibi 2015] [Terwilliger and Ison 2014] [The Control of Multiple 2026] [Timis and Dulf 2024] [Tinoco] [Toussaint et al 2007] [Trotsyuk and Lesohorskyi 2026] [Tsourdos et al 2010] [Tzes et al 2023] [Unmanned Aerial Vehicle Path 2014] [Unmanned Aerial Vehicle Collaboration 2026] [Unmanned Air System Search 2012] [Unmanned Autonomous Vehicle 2016] [Unnikrishnan and Prasad 2004] [Valianti et al 2023] [Vanualailai et al 2013] [Varela 2014] [Venugopalan et al 2012] [Volovoda 2024] [Wagner et al 1990] [Wallis et al] [Wang et al 2022] [Wang et al 2024] [Wang et al 2021] [Wang et al 2016] [Wang et al 2021] [Wang et al 2023] [Wang et al 2025] [Wang et al 2023] [Wang et al 2024] [Wang et al 2020] [Wang et al 2022] [Wang et al 2023] [Wang and Wang 2024] [Wang et al 2024] [Wang et al 2024] [Wang et al 2026] [Weiskopf et al 2002] [Wu et al 2025] [Wu and Han 2019] [Wu et al 2025] [Xi and Liu 2020] [Xia et al 2023] [Xu and Carrillo 2015] [Xu and Chen 2021] [Xu et al 2025] [Xu et al 2024] [Xu et al 2019] [Xu et al 2024] [Xu et al 2022] [Xu and Zhou 2025] [Xuan et al 2022] [Yan et al 2025] [Yang et al 2014] [Yang et al 2025] [Yang et al 2025] [Yang et al 2025] [Yang et al 2024] [Yang et al 2020] [Yang et al 2025] [Yang et al 2019] [Yao et al 2024] [Yoo et al 2021] [Yoo et al 2022] [Yoon et al 2009] [Yoon and Kim 2010] [Yoon and Kim 2017] [Yu et al 2025] [Yu et al 2024] [Yu et al 2023] [Yu et al 2023] [Yu et al 2024] [Yuan and Fang 2024] [Yuan et al 2023] [Yunhui et al 2024] [Zhang et al 2023] [Zhang et al 2024] [Zhang et al 2020] [Zhang et al 2026] [Zhang et al 2026] [Zhang et al 2019] [Zhang et al 2020] [Zhang et al 2024] [Zhang et al 2026] [Zhang et al 2020] [Zhang et al 2026] [Zhang et al 2022] [Zhang et al 2023] [Zhang et al 2016] [Zhao and Huang 2018] [Zhao and Li 2021] [Zhao et al 2026] [Zhao and Zhu 2016] [Zheng and Duan 2023] [Zheng et al 2026] [Zheng et al 2024] [Zheng et al 2026] [Zheng et al 2019] [Zhou et al 2014] [Zhou et al 2020] [Zhou et al 2024] [Zhou et al 2024] [Zhou et al 2026] [Zhou et al 2024] [Zhou et al 2024] [Zhou et al 2022] [Zhu et al 2013] [Zhu et al 2024]

291 of its 420 dated records were published after 2017, the year the number was allocated. 137 titles concern air combat, and 119 name a reinforcement-learning method.

Attrition, exchange and the arithmetic of losing things

The operations research that makes attritability computable. It holds Lanchester and other attrition models, salvo and combat models, exchange ratios, campaign analysis and historical loss rates. The cluster holds 154 records.

154 records. [Ackroyd 1992] [Adomian 1986] [Amacher and Mandallaz 1986] [Ancker et al 1988] [Anderson 1995] [Anderson et al 1976] [Appendix 1 Salvo Combat 2022] [Appendix A A Note 1996] [Armstrong 2005] [Armstrong 2006] [Armstrong 2011] [Armstrong 2013] [Armstrong 2014] [Army Concepts Analysis Agency Bethesda Md 1995] [Ash 1960] [Bach et al 1962] [Bailey 2001] [Barfoot 1969] [Bathe et al 1989] [Bauman 1997] [Billard 1979] [Billard 1979] [Bonder 1967] [Bonder 1970] [Brooks and DeRiggi 1990] [Brown 1955] [Bueil et al 1968] [Chen 2002] [Chen 2003] [Claussen and Carraro 2026] [Cody 2026] [Cohen 1991] [Cohen 1991] [Coulon 1975] [Coulson 2018] [Coulson 2025] [Cowdale 2014] [Davis et al 1978] [DeLiso 1999] [Dolanský 1964] [Exchange Ratios] [Fowler and Cason 1997] [Gafarian 1990] [Grubbs and Shuford 1973] [Hague 1982] [Hague 1983] [Hall and Betts] [Hammerman 1982] [Harris et al 1985] [Hausken and Moxnes 2000] [Haysman and Wand 1984] [Helmbold 1966] [Helmbold 1993] [Helmbold 1995] [Helmbold 1997] [Hester and Tolk 2009] [Hughes 1995] [Hunt and Azmy 1992] [Hwang and Lee 2023] [Isac and Gosselin 2008] [Ito et al 2020] [Ivancevic et al 2018] [Jaiswal 1997] [Jaiswal 1997] [Jaiswal and Nagabhushana 1994] [Jaiswal and Nagabhushana 1995] [Jing et al 2017] [Johns et al 2001] [Kaifang Wan and Gao 2011] [Kaimakamis and Zographopoulos 2012] [Karacan et al 2019] [Karmeshu and Jaiswal 1986] [Karr 1974] [Karr 1975] [Karr 1976] [Karr 1976] [Karr 1977] [Karr 1977] [Keane 2011] [Kim et al 2017] [Kimbleton 1971] [Koyuncu and Bostanci 2009] [Kress et al 2018] [Kress and Talmor 1999] [Lanchester 1955] [Lanchester, Frederick William 1868-1946 2017] [Lepingwell 1987] [Lepingwell 1990] [Li et al 2025] [Liu et al 2022] [Long 1994] [Lucas and Dinges 2004] [Lucas and Turkes 2003] [Macho-Stadler 2024] [MacKay] [Mangel 1979] [Mangulis 1980] [Mann 1976] [Mann 1978] [McGuire 1986] [Menq et al 2007] [Mittal 2023] [Mittal and Gillespie 2026] [Moving beyond attrition in 2023] [Palmore 1996] [Parry and Schoenstadt 1990] [Perry 2003] [Peterson 1967] [Pettit et al 2003] [Priest 1995] [Protopopescu et al 1990] [Reconstructing Lanchester Warfare Models 2021] [Rusu 1988] [Salim Al-khalidi and Hamid 2001] [Schold and Mittal 2024] [Schwartz 1988] [Shakir 1996] [Shirkey 2009] [Singh and Singh 1991] [Speight 1995] [System dynamics applications for 2021] [Tam 1998] [Tang and Li 2012] [Taylor 1971] [Taylor 1972] [Taylor 1973] [Taylor 1974] [Taylor 1974] [Taylor 1979] [Taylor 1979] [Taylor 1979] [Taylor 1979] [Taylor 1980] [Taylor 1980] [Taylor 1981] [Taylor 1982] [Taylor 1982] [Taylor 1983] [Taylor 1983] [Taylor 1984] [Taylor and Brown 1976] [Taylor and Brown 1978] [Taylor and Comstock 1977] [Trang and Usami 2017] [Vu 2023] [Wang et al 2016] [Washburn 2000] [Washburn and Kress 2009] [Washburn and Kress 2009] [Weinberg 2025] [Weiss 1966] [Wiper et al 2000] [Xu et al 2012] [Zhang 2023]

89 of its titles name Lanchester, and its median publication year, 1994, is the earliest of any cluster, with the cost cluster next.

Surviving a defended sky, or not having to

Survivability is the variable attritability trades against, and the trade is the design. It holds the susceptibility and vulnerability of aircraft, radar cross-section and signature reduction, stealth shaping, air defences, electronic attack and the suppression of enemy air defences. The cluster holds 167 records.

167 records. [Ahn et al 2002] [Airborne Hydraulic and Control] [Aleisa et al 2024] [Alexandrov 2017] [Altman 2008] [An Experimental Study on 2008] [Antonakis et al 2019] [APPENDIX 1. The Suppression 2017] [Appendix A Survivability Features 1985] [Appendix A Survivability Features 2003] [Appendix B Probability Theory 1985] [Appendix B Probability Theory 2003] [Army War Coll Carlisle Barracks Pa 1982] [Atkinson et al 1969] [Avery et al 1971] [Bacci and Vagias 2023] [Baldwinson and Antipov 2008] [Ball 1985] [Ball 2003] [Ball and Atkinson 1998] [Barkdoll et al 2002] [Berens 2003] [Bernier et al 1982] [Bezandry et al 2016] [Biggs and McMillian 1980] [Bing et al 2026] [Bishop 1989] [Bistatic and Multistatic Radar 1997] [Bistatic and Multistatic Radar 1998] [Bo et al 2025] [Borison 1965] [Bridgman 1981] [Buckner 2000] [Cao et al 2011] [Caravasos 1991] [Cas Inc Huntsville Al 1992] [Chase et al 1999] [Chen et al 2011] [Chen and Liu 2018] [Cheng et al 2016] [Chu and Ma 2009] [Connelly 1981] [Deng et al 2024] [Department Of Defense Washington Dc 2002] [Design for Stealth 2010] [Designing for Survivability Stealth 2010] [Doan et al 1995] [Einarsson et al 1966] [Elton 1990] [Erkan et al 2008] [Erma 1965] [Erma 1967] [Faisal et al 2024] [Farrell et al 1982] [Fenn 1990] [Flow Visualization Study on 2007] [Forrester] [Fralish 1998] [Freeny and Ross 1964] [Freeny and Ross 1964] [Fry 2008] [Gautam et al 2025] [Gaver and Jacobs 1998] [Ge et al 2024] [Gilson 1994] [Gowd and Sahu 2023] [Greene and Hevert 1973] [Griffin 1975] [Guzie 2004] [Hall et al 2009] [Haque et al 2013] [Hazinedar 2015] [He et al 2025] [Holland and Cho 1986] [Hu et al 2022] [Hu et al 2025] [Hydraulic System Survivability for] [Hydraulic System Survivability] [Introduction to the Aircraft 1985] [Introduction to the Aircraft 2003] [James 1988] [Ji et al 2024] [Jiapan and Yongshan 2021] [Jin et al 2024] [Jin et al 2023] [Jung et al 2024] [Jung et al 2015] [Kan] [Khurramov and Bobomurodov 2021] [Kim et al 2019] [Kula 2009] [Kurdyla 1963] [Lee et al 2008] [Liu et al 2023] [Lohrmann 2001] [Lowry et al 1978] [Manley 2018] [Masters 1986] [Metasurface-Driven Electronic Attack 2024] [Mishra et al 2022] [Mukherjee 2021] [Mustopa 2022] [Narayanan 2002] [Noh and Choi 2012] [Papageorgiou 2022] [Paterson 1999] [Paterson and Paterson 1997] [Pathak 1975] [Pei et al 2014] [Pennsylvania State Univ University Park 2001] [Queen 1976] [Queen et al 1977] [Renau and Tavis 1972] [Rickman et al 1976] [Ridder and HandUber 2005] [Borek 2005] [Robillard and Blore 1964] [Ru et al 2026] [Ruck and Krichbaum 1968] [Sands 2009] [Schilling 1978] [Schoendorf 1972] [Schultz et al 1964] [Sijabat and Indriyanto 2021] [Siotia et al 2026] [Sleator 1964] [Smith 2003] [Smith et al 1964] [Smith et al 1978] [Smith and Starks 2011] [Smith and Williams 1993] [Soldatov et al 2025] [Stadmore 1979] [Steele and Barnum 1966] [Steenrod and Musch 1981] [Stegall 2001] [Stoneking et al 2006] [Stradtner et al 2020] [Suminsby 2002] [Support Jamming Electronic Attack] [Survivability PS and PK 1985] [Survivability PS and PK 2003] [Taflove and Umashankar 1989] [Taha and Hajj 2013] [Tavis 1973] [Throndson 1981] [Throndson 1982] [Vice 1986] [Vice 1987] [Wang et al 2024] [Wei et al 2021] [Weiss 1968] [Wijaya 2025] [Wolfe and Ruda 1979] [Wright 1975] [Wu et al 2026] [Xiang et al 2023] [Yang 2017] [Yang 2024] [Yi et al 2019] [Zhang et al 2023] [Zhang et al 2025] [Zhang et al 2025] [Zhang et al 2021] [Zhang et al 2024] [Zhang et al 2025] [Zhou et al 2021]

43 titles name radar cross-section, 40 name stealth or low observability, and 12 name the suppression of enemy air defences, the mission the production Valkyrie is intended to fly.

Being a node rather than a platform

The aeroplane has acted as a relay between two fighters, which is a communications role rather than a combat one. It holds airborne and unmanned-aircraft relays, airborne and tactical networks, and datalinks. The cluster holds 43 records.

43 records. [Al-Hourani and Kandeepan 2013] [Bass 2006] [Bostian and Young 2011] [Bostian and Young 2013] [Bretmersky et al 2014] [Carney 2008] [Cetin and Zagli 2011] [Chen et al 2023] [Cooperative Communications in UAV 2020] [Cyber-Physical System Modeling on 2013] [Du and Swamy 2026] [Ferrão] [He et al 2021] [Howard 2005] [Khan 2021] [Koo 2012] [Kumaravelu et al 2022] [Lee et al 2018] [Li and Liu 2012] [Li et al 2024] [Liu 2022] [Ma et al 2024] [Oh et al 2019] [Pabon Arias] [Park and Kim 2026] [Pi et al 2023] [Reichstein et al 2022] [Sagduyu et al 2018] [Sheng et al 2023] [Shi et al 2018] [Tao et al 2024] [Unmanned Aerial Vehicle UAV 2022] [Waggener 1987] [Wang et al 2024] [Wang Yun-sheng et al 2016] [Wiersgalla 2011] [Wireless Communications and Networking 2020] [Wu et al 2019] [Yan 2025] [Zhang et al 2026] [Zhang et al 2024] [Zheng et al 2025] [Zolanvari et al 2018]

Leaving the ground without a runway, and coming back without one

Launch and recovery without an airfield, which the article computes rather than describes. It holds catapults, rails, rocket-assisted and zero-length launch, parachute recovery, canopy inflation and loads, airbags and other impact attenuation, and the recovery of spacecraft and boosters, whose parachute physics is the same. The cluster holds 218 records.

218 records. [Afridi et al 2026] [Alizadeh et al 2014] [Analysis of the Working 2016] [Andrews] [Aruvelli 2020] [Astorg and Barreau 1995] [Bacchus et al 1975] [Badowski 2015] [Banerjee and Utreja 1975] [Barmada et al 2022] [Baumgartner et al 1979] [Behr 1989] [Behr 1989] [Behr 1991] [Behr 1993] [Behr 1999] [Bertola et al 2015] [Bertola et al 2016] [Bleier et al 2015] [Bolton 1979] [Bolyukh et al 2020] [Bown and Darley 2005] [Bradshaw 1980] [Brearley 1969] [Brodersen and Sauer 1990] [Brown et al 1991] [Butler and Montanez 2007] [Butler and Loney 1995] [Cadogan et al 2002] [Cannon and Koch 1989] [Cassanto et al 1968] [Catch a Falling Star 1993] [Clifford and Hengel 2009] [Cockrell and Haidar 1993] [Cooper et al 2005] [Corwin et al 1986] [Cowan et al 2025] [Cruz 2022] [Darley et al 2013] [DeLoach and Lyle 2009] [Santis] [Santis 1973] [Dinh] [Do et al 2009] [Doherr and Schilling 1991] [Drynan] [Du 2013] [Dynamic Response Analysis of 2021] [Ericksen et al 1966] [Everett 1973] [Eymann and Martel 2008] [Farhall et al 2007] [Fatykhov 1993] [Fields and Norris 2022] [French 1988] [From Hegemony to Competition 2022] [Gaborit et al 2005] [Gao et al 2017] [Goerttler and Schnepf 2022] [Goerttler and Schnepf 2024] [Gong and Wu 2021] [Gonzalez 2010] [Goodrick 1969] [Grumondz et al 2018] [Guidotti et al 2012] [Guo et al 2025] [Hahne and Fremaux 2008] [Hassett 2024] [He et al 2015] [He et al 2014] [He et al 2023] [Henry et al 2017] [Herrington et al 2019] [Aerospace Design Co Inc Bedford Ma 1987] [Huh and Shim 2010] [Huxley-Reynard 2001] [Iyer et al 2025] [Janda et al 2013] [Jann 2026] [Jastrzębski et al 2018] [Jizhu Liu et al 2009] [Johnson 1986] [Johnson 1989] [Johnson and Hixson 2008] [Jossie 2007] [Jóźko and Włodarczyk 2020] [Kandis and Witkowski 2019] [Kennedy and Lowry 1995] [Knacke 1985] [Knapik et al 2011] [Kostelezky 2005] [Kostelezky and Schmitt 1999] [Koster et al 2011] [Kozlov 2013] [Krause et al 2024] [Layfield and Carpenter 1995] [Ledyankina et al 2018] [Lee et al 2008] [Lee et al 2008] [Lempert 1975] [Levin and Shpund 1995] [Li and Chen 2019] [Li et al 2025] [Lingard et al 2013] [Liu et al 2007] [Lloyd et al 1978] [Lyalin and Morozov 2005] [Machin et al 2001] [Machin et al 2011] [Machin et al 2011] [Mansfield 1973] [McMenamin and McMenamin 1997] [McMenamin and Pochettino 1984] [Mehaffie 1979] [Menting et al 2020] [Merz et al 1970] [Mkrtchyan and Johari 2011] [Moog et al 1979] [Moog and Kross 1982] [Moog et al 1979] [Morris and Olson 2011] [Neustadt et al 1967] [O’Farrell et al 2016] [Olcer 2015] [Paul and Paul 2023] [Pearson 1972] [Pei 2019] [Pei et al 2019] [Pepermans et al 2018] [Pepper 1977] [Pepper and Collins 1982] [Pepper and Collins 1981] [Peterson et al 1986] [Peterson et al 2024] [Pilyugin and Khlebnikov 2010] [Placco et al 2025] [Prkačin et al 2024] [Reinhard et al 1997] [Rocket-Assisted Take-Off for the 1965] [Runkle and Drobnik 1979] [Runkle and Wolf 1995] [Sahu et al 1997] [Schatzle and Curry 1979] [Schatzle and Curry 1980] [Sengupta et al 2009] [Shang et al 2025] [Shao et al 2013] [Shen and Liu 2025] [Shen et al 2025] [Shi et al 2022] [Shim et al 2008] [Shook et al 2009] [Shyu and Hsiao 2014] [Silbert et al 1986] [Slade et al 2006] [Smith et al 2007] [Specification for Design and] [Specification for Aircraft Emergency] [Standard Specification for Aircraft] [Stein et al 2003] [Stewart 2013] [Suit et al 1964] [Szczepaniak et al 2019] [Talay and Poole 1971] [Thomas and Thomas 2008] [Tiaden and Yakimenko 2008] [Tiaden and Yakimenko 2009] [Timmers et al 2009] [To] [Toni 1970] [Tupitsin and Stepanenko 2020] [Tutt et al 2009] [Tutt et al 2022] [Tutt et al 2009] [Underwood et al 2022] [Vergnolle 1995] [Vu et al 2021] [Wachlin et al 2022] [Wailes 1989] [Wang et al 2013] [Watkins 1986] [Watkins et al 2017] [Watson and Gonzalez 2023] [Waye et al 1995] [Waye et al 1986] [Wei and Pearson 1974] [Wei et al 2015] [Welch 2007] [Whalley 1973] [Whitmore and Hennings 2007] [Whitmore et al 2004] [Witkowski 1999] [Witkowski 1999] [Witkowski et al 2022] [Wolf 1991] [Wolf and Fallon 2011] [Worth 1965] [Worth 1966] [Wu et al 2019] [Wu et al 2020] [Wyllie 2001] [Wyllie et al 1997] [Xiang and Zhou 2025] [Xie et al 2015] [Xue et al 2019] [Xue et al 2015] [Xue et al 2019] [Yakimenko et al 2008] [Yeakle et al 2009] [Yıldırım Dalkıran and Kırteke 2024] [Yin et al 2021] [Yin and Wen 2012] [Zakaria 2013] [Zhou and Huang 2020] [Zhou et al 2019] [Zhu et al 2018] [Zhu et al 2019] [Zhurin 2019]

139 of the 218 titles concern a parachute, a canopy, a drogue or a parafoil, 36 an airbag or impact attenuation, and 33 a catapult, a launch or a take-off.

Range, endurance and the fuel it takes

The cruise performance the published range implies, and the engine question it does not settle. It holds the range equation, cruise and endurance performance, specific fuel consumption, and aircraft and missile gas turbines and their components. The cluster holds 160 records.

160 records. [A Means of Testing] [Aircraft Range and Endurance 2011] [Aircraft Range and Endurance 2011] [Air Force Research Lab Edwards Afb Ca 2000] [Amer 1965] [Andersen and Bagby 1965] [Anderson 1970] [Anderson 1986] [Andoga et al 2026] [Armstrong et al 1980] [Atasoy and Cetek 2020] [Aygun and Turan 2021] [Aygun and Turan 2023] [Baer-Riedhart 1982] [Baerst and Sandborn 1978] [Bagby and Andersen 1966] [Balli et al 2018] [Bardell 2000] [Batra et al 2023] [Batra et al 2024] [Batra et al 2026] [Berman 1997] [Bilimoria 1989] [Borst 1978] [Bowers et al 2026] [Briones et al 2020] [Bristol Siddeley Viper Mark 1963] [Brodzik 2024] [Brun et al 2014] [Catchpole 1990] [Cavcar 2006] [Cavcar and Cavcar 2003] [Cestino et al 2023] [Chapman 1979] [Chen 2021] [Chin et al 1974] [Chippa 2010] [Cican et al 2023] [Cican et al 2027] [Climbing Flights of Turbojet 1995] [Coalson 1968] [Crouse and Sash 2004] [Cruise Performance 2012] [Cruise Performance and Flight 2021] [Cruise Performance 2022] [Cruising Flights of Turbojet 1995] [Determination of erosion in 1959] [de Vries et al 2020] [Di Giorgio et al 2025] [Doman 2015] [Dommasch et al 1959] [Dr and Bhuvan Kumar 2026] [Dugas 1986] [Eggers 1961] [Ekici et al 2024] [Evans and Chamblee 1966] [Fernandes Pereira de Lima and Souto 2021] [Flight engine performance evaluation 1977] [Fouellefack et al 2022] [Főző and Andoga 2022] [Fredericks 2010] [Gedeon and Takahashi 2014] [Glīzde] [Goraj et al 1999] [Gray and Dugan 1975] [Gürbüz et al 2021] [Hale 1973] [Hale and Steiger 1978] [Hale and Steiger 1979] [Harish et al 2022] [Herrmann 2004] [High-Altitude Long-Endurance HALE Sensor 2026] [Hong et al 2024] [Howard 1990] [Hriadel et al 2026] [Hubble and Smith 1979] [Ilić et al 2016] [Jameson 2009] [Chapman 2023] [Jerie 1975] [Ji et al 2019] [Kang and Ryu 2021] [Khalid 2016] [Khalid 2017] [Kidder 1957] [Kim et al 2001] [Kim et al 2026] [Kuhn et al 1981] [Kuhn et al 2026] [Kutney 1964] [Kuznetsov and Shpakovsky 2020] [Laitone 1978] [Larson 1958] [Li and Rodrigues 2025] [Lockwood 1964] [Luca et al 2024] [Mauch et al 1980] [Mehalic and Ziemianski 1980] [Merrill 1976] [Meyer et al 2007] [Miller 1993] [Mishra et al 2023] [Montazeri-Gh and Yousefi Dastjerdi 2024] [Most and Feasey 2021] [Mosyam and Ardian 2026] [Mushynski and Johnson 2017] [Muslu et al 2026] [Nelson and Dix 2003] [Nguyen et al 2025] [Ojha 1992] [Optimization of Cruising Flights 1995] [Oruc and Baklacioglu 2024] [Palaia 2026] [Pan et al 2022] [Patel et al 2018] [Patterson 1989] [Phase 2 program on 1975] [Phillips et al 2019] [Practice for Design and] [Practice for Design and] [Practice for Design and] [Preparation of turbojet engine 2002] [Randle et al 2011] [Ravishankar and Chakravarthy 2018] [Retana and Rodriguez-Cortes 2007] [Richardson and Tommasini 1967] [Roseberg 1982] [Rotaru et al 2016] [Rudnitski] [Rutkay and Laliberté 2016] [Sanders 1965] [Schacht-Rodriguez et al 2019] [Schober and Franklin 1968] [Scholz 2021] [Selection of Bypass Ratio 2003] [Selection of Fan Pressure 2015] [Sforza 2020] [Sharpe et al 2021] [Shivers and Smith 1974] [Shivers and Smith 1975] [Spaight and Selfors 1967] [Staack et al 2021] [Suh 1990] [Szafranski et al 2014] [Tate and Gillard 1975] [Turner Camacho and Danforth 2026] [Turning Flights of Turbojet 1995] [Unified Cruise Performance 2013] [van Es 2002] [Villarreal-Valderrama et al 2020] [Villette et al 2026] [wang et al 2022] [Ward and Neeley 1959] [White and Strykowski] [Wroblewski and Ansell 2020] [Young 2010] [Yucer 2026] [Yucer and Nacakli 2023] [Zhao 2003] [Ziemianski 1981]

46 titles name a turbojet and 30 a turbofan or a bypass ratio, and 17 name the Breguet relation or a range equation.

Sizing the aeroplane around the constraint

Constraint analysis, which is where a cost target becomes a wing, and the wing area of this one is not published. It holds conceptual design, initial sizing, the selection of wing loading and thrust to weight, and design optimisation of unmanned aircraft. The cluster holds 44 records.

44 records. [Aleisa et al 2023] [Batill et al 1999] [Belart 1938] [Bergman 1979] [Bowles et al 1976] [Concept Design Initial Constraint 2017] [Cong et al 2025] [Cummings et al 2018] [Cunningham 1976] [Estimating the Takeoff Wing 2010] [Ganglin 2009] [Gómez Rodríguez] [Hailes et al 1994] [Hartney 2012] [Hong et al 2021] [Hutchinson 1932] [Ibrahim 2002] [Initial Unmanned Aircraft Sizing 2014] [Initial Unmanned-Aircraft Sizing 2012] [Jagtap 2025] [Junlei et al 2017] [Karabetsky 2018] [Khreish et al 2005] [Kim and Lee 2011] [Kim and Lee 2018] [Kumar et al 2026] [Lee and Yee 2024] [Liersch and Bishop 2018] [Liersch and Huber 2014] [Neufeld 2021] [Neufeld and Chung 2005] [Nikbay et al 2025] [Parker 1986] [Saraswat and Pant 2025] [Sathe and Pant 2010] [Sharif 2022] [Skillen and Crossley 2005] [Svoboda 1999] [Thrust-to-Weight Ratio and Wing 2024] [Vos 2019] [Wilt et al 2022] [Woolvin 2006] [Yang and Yee 2022] [Yoon et al 2026]

Unmanned airframes and their aerodynamics, the combat configurations above all

The airframe literature of unmanned aircraft, most of it on combat configurations. It holds the aerodynamics, stability, loads and aeroelasticity of unmanned airframes, measured and computed. The cluster holds 94 records.

94 records. [Aerodynamic Performance of Lambda 2024] [Aleisa et al 2022] [Aleisa et al 2023] [Alex 2014] [Al-hussien et al 2026] [Allen et al 2018] [Anderson 1999] [Anwar et al 2021] [Arthur and Petterson 2007] [Atkinson and Ferguson 2006] [Chandrasekhara and McLain 2013] [Chen et al 2023] [Chung and Ghee 2006] [Coppin and Birch 2014] [Coppin and Qin 2013] [Cummings et al 2003] [Cummings and Schütte 2012] [Dai et al 2023] [Da Ronch et al 2018] [Deepa et al 2016] [Design and Fluid Flow 2015] [Elkhoury 2008] [Elkhoury and Rockwell 2004] [Elkhoury et al 2005] [Flow Control and High-Lift 2016] [Frink 2014] [Frink et al 2012] [Fung and Amitay 2002] [Gc] [Ghee 2002] [Ghee 2003] [Ghee and Hall 2000] [Ghoreyshi et al 2014] [Goraj 2005] [Gordnier et al] [Haider 2025] [Haider et al 2023] [Hitzel et al 2009] [Hitzel and Zimper 2014] [Hoholis et al 2016] [In et al 2007] [Ishak et al 2025] [Isnard et al 2023] [Jo et al 2014] [Jo et al 2015] [Foster et al 2020] [Jones et al 2006] [Kaya et al 2018] [Kaya et al 2019] [Kennett et al 2014] [Lofthouse and Cotton 2017] [Luckring and Boelens 2015] [Lynn and Gursul 2006] [Marques 2013] [Marques 2014] [van Rooij et al 2019] [Milne and Arthur 2006] [Nangia et al 2018] [Nangia et al 2019] [Nangia and Palmer 2006] [Nangia and Palmer 2011] [Ol 2006] [Ordaz et al 2004] [Park et al 2016] [Park et al 2017] [Petterson 2006] [Petterson 2006] [Prasad 2025] [Reichenbach 2003] [Ruetten 2018] [Ruetten et al 2014] [Sudhakar et al 2025] [Sakarya et al 2018] [Schuette et al 2014] [Schütte et al 2012] [Selig 2010] [Sherer et al 2008] [Sun et al 2026] [Tekin et al 2026] [Tomac et al 2012] [Vallespin et al 2011] [van Rooij and Cummings 2018] [Vicroy et al 2014] [Vicroy et al 2012] [Vicroy et al 2014] [Voss et al 2011] [Voss and Klimmek 2016] [Voss and Klimmek 2016] [Wang and Zhou 2022] [Young et al 2014] [Zarei and Maadi 2026] [Zimper and Huber 2019] [Zimper and Hummel 2014] [Zimper and Hummel 2018]

80 of the 94 titles name an unmanned combat aircraft, and 36 concern a generic, representative or shared research configuration, such as the 1303, SACCON and MULDICON models.

Flight control, guidance and navigation without a pilot

What replaces the pilot in the loop. It holds the flight control laws, state estimation, navigation, envelope protection and automatic landing of unmanned aircraft. The cluster holds 162 records.

162 records. [Acosta et al 2016] [Advanced Control Techniques for 2023] [Aerospace - Vehicle Management] [Alatorre Sevilla] [Alexis and Tzes 2012] [Al-Mahturi et al 2021] [Anandharaman et al 2016] [Approach to solving the 2025] [Askri et al 2010] [Azimov and Allen 2017] [Baughman and Longeauay 2015] [Benders and Koch 2019] [Bernstein 2000] [Bodson 2001] [Bonyan Khamseh 2021] [Burnashev and Zbrutsky 2019] [Carryer] [Ceren and Altuğ 2011] [Chan] [Chen et al 2024] [chen et al 2024] [Chen et al 2024] [Chen and Zhao 2017] [Cheng and Pei 2021] [Chitrakaran et al 2005] [Coombes et al 2017] [Cunis] [Dahleh and Tsitsiklis 2002] [Davidson 2004] [Dermer] [Design of a Low-Cost 2005] [Development of Automatic flight 2004] [Dickes et al 2002] [Din et al 2023] [Dorobantu et al 2013] [Dragos Daniel et al 2026] [Ducard and Geering 2008] [Duggan and Bhandari 2021] [Eaton and Chen 2015] [Fahimi and Thakur 2013] [Fang 2025] [Forkun et al 2020] [Fukushima and Tsubone 2019] [Girish et al 2014] [Gomez and la Cour-Harbo 2021] [Hajiyev et al 2015] [Hajiyev et al 2015] [Hajiyev et al 2015] [Hajiyev et al 2015] [Hajiyev et al 2015] [Hajiyev et al 2015] [Hajiyev et al 2015] [Hajiyev et al 2015] [Hajiyev et al 2015] [Hamadi] [Hamnanaka 2018] [Hanif and Sasongko 2019] [Hansu Dai and Jihong Zhu 2010] [He et al 2022] [Hegde 2020] [Hoffer et al 2013] [Hoffer et al 2014] [Hoffer et al 2015] [Hossny et al 2020] [How et al 2014] [Hu and Huang 2017] [Ibraheem 2019] [Jafari et al 2017] [Jafari and Xu 2018] [Jianhong and Yanxiang 2026] [Johnson et al 2005] [Jung et al 2014] [Kannan et al 2014] [Ke et al 2015] [Kharchenko et al 2017] [Khobin and Goncharenko 2021] [Klenke and Ortiz 2011] [Krishnamoorthy] [Kuwamura and Hara 2017] [Lanteigne and O’Reilly 2020] [Laubendorfer et al 1965] [Lee et al 2008] [Lee and Tahk 2019] [Li and Li 2010] [Lieret et al 2022] [Liu Zhi and Wang Yong 2012] [Lu et al 2019] [Lu et al 2011] [Ludington et al] [Luo et al 2019] [Ma] [Malyar and Shcheholskyi 2026] [Maria-Agneta and Stef 2011] [McLaughlin] [Merheb] [Motter and High 2009] [Mueller 2018] [Naundrup] [Neto et al 2024] [Nguyen et al 2024] [Opromolla 2020] [Pham] [Podhradsky et al 2013] [Prasad and Unnikrishnan 2006] [Protsenko et al 2019] [Raja 2011] [Ramasamy 2015] [Ramasamy et al 2015] [Rithirun and Sooraksa 2013] [Rogalski 2018] [Rohlf et al 2012] [Sabatini R 2013] [Saied] [Salguero and Rhudy 2017] [Sarabakha] [Sendner et al 2018] [Sherstjuk 2015] [Simmons et al 2023] [Simms 2023] [Sims] [Sims and Biezad 2010] [Sineglazov and Daskal 2017] [Song 2008] [Souli et al 2025] [Stachura and Frew 2011] [Sun and Pack 2016] [Sushchenko and Goncharenko 2016] [Szabolcsi 2018] [Szabolcsi 2018] [Szabolcsi 2018] [Tang] [Tanveer and Ahmad 2023] [Tiwari] [Tomczyk and Rogalski 2005] [Tsai et al] [Tuzcu 2007] [UAV Control 2016] [Unmanned Aerial Vehicle Dynamics 2016] [Ure and Inalhan 2009] [Usach Molina] [Velasco Carrau] [Vepa 2016] [Vepa 2023] [Vepa 2026] [Vepa 2026] [Wang et al 2010] [Xiao and Jiancheng 2005] [Xu 2009] [Xu et al 2023] [Yang et al 2019] [Yu et al 2023] [Zafirov 2010] [Zakharin and Ponomarenko 2017] [Zbrutsky et al 2024] [Zhang] [Zhang and Bradley 2022] [Zhang et al 2011] [Zhang and Qin 2026] [Zhang et al 2022] [Zhong et al 2026] [Zhou et al 2025] [Żugaj 2017]

Unmanned aircraft in doctrine, programmes, operations and history

The unmanned aircraft as a military instrument. It holds doctrine, programmes, operations, law, ethics and history. The cluster holds 87 records.

87 records. [Ahern et al 1993] [Alexander 1979] [Banks 2000] [Baxter 2013] [Bookstaber 2000] [Booz-Allen And Hamilton Inc McLean Va 2000] [Boutros 2015] [Bozov 2023] [Brown 1998] [Buchanan 2010] [Burke 2015] [Carr et al 2003] [Chapa 2017] [Cherednychenko et al 2022] [Chittenden 2013] [Clark 1999] [Clark 2000] [Cote 2015] [Crutchfield 2003] [DeJarnette-Crumsey et al 2022] [Department Of The Air Force Washington Dc 2005] [Digman 2009] [Dodge 2015] [DoD Office of Inspector General 2015] [Edwards and Lennie O. 1990] [Fant 2001] [Franke 2016] [Frey 2011] [González 2023] [Grisworld 2008] [Haritos and Barnhart 2021] [Hinchman 2002] [Historical Aspects of Unmanned 2016] [Holland et al 2009] [Howard 1995] [Howard 1996] [Ironhill et al 2013] [Ivanets et al 2025] [Jayanthi et al 2022] [Jenkins et al 2005] [Johnson and O’Neill 2003] [Kaymal 2016] [Keleş 2022] [Khalatov et al 2023] [Klein 2002] [Kumar 1997] [Kumar 2020] [Larm 2004] [Lewis 2002] [Longino 1994] [Matsushima 2001] [Moser 2011] [Multi-Rotors A Revolution In 2015] [Nadler 2015] [Neuenswander 2013] [Nichols 1998] [Nichols 2021] [Okcu 2016] [O’Reilly 1999] [Pauls 2012] [Payton 2011] [Perry 2000] [Peterson and Staley 2011] [Petrock and Huizenga 2006] [Radovanović et al 2023] [Renehan 1997] [Review of ONR’s Uninhabited 2000] [Sager 2009] [Snyder 2000] [The Future of Unmanned 2016] [The origins of unmanned 2017] [Thome 2003] [Tweddale et al 2011] [UAV Systems Continuing Evolution 2010] [Unmanned Aerial Vehicles UAVs 2015] [Unmanned Aerial Vehicles for 2016] [Valavanis and Kontitsis] [Van Dyke et al 1990] [Wills 2015] [Wills 2015] [Wise 2003] [Wise 2004] [Worch et al 1996] [Wrage 2011] [Wyatt 2003] [Yao et al 2018] [Yuma Proving Ground Az 2013]

56 of its 87 records are Defense Technical Information Center reports.

The people who fly unmanned aircraft from the ground

The crews who fly unmanned aircraft from the ground. It holds operator selection, training, workload, interfaces and the human causes of accidents. The cluster holds 32 records.

32 records. [Billings and Durlach 2008] [Billings and Durlach 2010] [Bishop 2019] [Callicoatt 2009] [Chappelle et al 2014] [Deutsch 2006] [Durlach et al 2012] [Gacy 2011] [Herrmann and Schmidt 2018] [Hinsz 2006] [Human Factors in Unmanned 2016] [Jensen 2016] [Jensen 2021] [Kucherov et al 2019] [Kurkcu et al 2011] [Manning et al 2004] [Mirchandani 2020] [Oliver 2012] [Oncu and Yildiz 2014] [Park and Geng 2023] [Pomranky 2006] [Rowe et al 2014] [Ss and Mathiyazaghan 2016] [Swearingen et al 2015] [Tvaryanas 2006] [Tvaryanas 2006] [Tvaryanas and Maupin 2013] [Tvaryanas et al 2012] [Walters et al 2002] [Weeks 2000] [Wickens and Dixon 2002] [Williams 2006]

The atmosphere and the flight condition

The medium, which is the setting here rather than the subject. It holds standard atmospheres, their tables and models, and the relations between pressure altitude, airspeed and Mach number. The cluster holds 36 records.

36 records. [A Properties of Standard 2006] [Air Force Test Pilot School Edwards Afb Ca 1962] [Appendix A. The Standard 2011] [Appendix A Standard Atmosphere 2021] [Appendix B Properties of 2003] [Brown 2012] [Essenhigh 2006] [Everett et al 1972] [International Standard Atmosphere 2010] [Johnson et al 1991] [Kang et al 2023] [Kang et al 2023] [Kaushik 2018] [Kurzke and Halliwell 2018] [Kurzke et al 2025] [Luo 2025] [Minzner et al 1976] [Pressures and Temperatures for 2000] [Properties of the U.S 2014] [Properties of the U.S 2024] [Space environment natural and] [Standard atmosphere chart 1927] [Standard atmosphere chart supersedes 1927] [Standard Atmosphere 2005] [Standard Atmosphere 2023] [Standard Atmosphere 2024] [The Flight Environment Standard 2021] [The International Standard Atmosphere 2017] [The international standard atmosphere 2026] [The Standard Atmosphere 1964] [The Standard Atmosphere 1976] [Turns and Kraige] [US Standard Atmosphere Model 2014] [Vaughan 2003] [White 2017] [White 2017]

Unmanned aircraft engineering in general

The residual, reported and not hidden. A record is placed here when its title is on the engineering of an unmanned aircraft, its design, structure, power, electronics, software, security, test and general overviews, and names no subject that a cluster above claims. No further subject in it is large enough to name, and dividing it further would describe the filing rather than the field. The cluster holds 140 records.

140 records. [Abdelrahman et al 2009] [Adelgren et al 2004] [Aerospace series. Unmanned Aircraft] [Alatishe et al 2007] [An Overview On Unmanned 2017] [Argrow 2016] [Austin 2010] [Bakirci and Ozer 2022] [Banfield et al 2016] [Deepak and Singh 2016] [Bhattacharya 2026] [Bramesfeld and Prinster 2015] [Brungardt 2011] [Burris et al 2011] [Burris et al 2011] [Bushey] [Cárdenas et al 2005] [Chapter 1 Overview of 2021] [Childers and Condon 2004] [Coe et al 2019] [Control for Wireless Charging 2025] [Corbetta and Kulkarni 2019] [Department Of Defense Washington Dc 1994] [Design and Implementation of 2020] [Drews and Forman 1999] [Edge et al 2010] [Eilertson 1975] [Environmental Control Systems ECS] [Eremin 2025] [Franco et al 2019] [Gabrousenko et al 2017] [Gambaryan 2021] [Gan et al 2017] [Gilli and Gilli 2018] [Gregory and Kim 2022] [Gupta et al 2019] [Habiba and Jahan 2023] [Hajiyev et al 2015] [Hammack and Mullen 1995] [Hann and Johansen 2020] [Hartney] [Herbst and Klöckner 2014] [Hovering Wireless Charging for 2025] [Introduction to Unmanned Aircraft 2010] [Jenks 2026] [Jorris et al 2011] [Kessler et al 2000] [Khan et al 2022] [King] [Kirk et al 2022] [Klipp et al 2021] [Kozlov 2013] [Kumari and Raghunath 2016] [Lei 2014] [Li and Tiniakov 2026] [Li and Tiniakov 2026] [Li and Tiniakov 2026] [Li and Tiniakov 2026] [Li and Tiniakov 2026] [Liu 2004] [Lokhande 2026] [Love and Argrow 2021] [Madanayaka et al 2026] [Magnetic Coupler Design for 2025] [Mahmoud and Mohamed 2014] [Maldonado et al 2017] [Malik 2024] [Manoilo 2025] [Galles et al 2018] [Mechatronic Design of Unmanned 2015] [Miesikowska 2017] [Mihalik and Keane 2022] [Most 2016] [Most and Stroup 2021] [Multi-Disciplinary Cyber-Physical Optimization for 2012] [Noise measurements for UAS] [Nugent and Girard 2003] [Operating an Unmanned Aerial 2018] [Overview of Unmanned Aircraft 2012] [Overview of Unmanned Aircraft 2014] [Ozyetis and Alemdaroglu 2014] [Panigrahi and Tripathy 2025] [Papandreas and Jacox 1994] [Park and Ro 2004] [Paz et al 2026] [Pham and Sim 2002] [Plaza del Pino et al 2024] [Podhradsky et al 2013] [Banerjee et al] [Pourgol-Mohammad and Khayati 2021] [Prior 2018] [Pyzynski 2020] [Quan et al 2025] [Rasmussen et al 2006] [Reghunath and Ramaiah 2022] [Reid et al 2004] [Ridgard 2008] [Ross et al 2019] [Sadraey 2010] [Sastry 2001] [Schiller and Zawodny 2018] [Scott 2021] [Semke 2016] [Semke 2021] [Sevcik and Oh] [Shahbazi 2025] [Slapnicar] [Sosa 1997] [Subramaniam et al 2012] [Sunil] [Takita and Kashitani 2016] [Taylor et al 2021] [Thompson and Robertson 1990] [Torres et al 2017] [Towhidnejad and Clifford 2009] [Tran] [Twesme and Corzine 2003] [UAV System Deployment 2010] [Unmanned Aerial Vehicles 2013] [Unmanned Aerial Vehicles 2020] [Unmanned Aerial Vehicle Design 2024] [Unmanned Air Vehicles 2017] [Unmanned Aircraft Categories 2012] [Unmanned Aircraft Vehicles 2013] [Unmanned Aircraft Categories 2014] [Unmanned Aircraft Geometry and 2014] [Unmanned Aircraft System Elements 2016] [Unmanned Aircraft System Operations 2016] [Unmanned-Aircraft Geometry and Configurations 2012] [Vashishth et al 2024] [Video Communications in Unmanned 2013] [Wang] [Webb 2022] [Westat Inc Rockville Md 2001] [Wigley and Jasiunas] [Wong et al 2015] [Yuma Test Center Yuma Proving Ground Az 2008] [Zawodny et al 2018] [Zhang et al 2025] [Zhang et al 2022]

Where the Framing Breaks Down, An X-Plane Is Too Precious to Lose and This One Is Not

The two halves of this article meet here. The X series exists to fly aeroplanes that answer questions, and an aeroplane that answers questions is protected, because losing it ends the answering. The Valkyrie exists to be lost, and its design follows from that.

The series supplies the contrast. The X-56 was built to flutter deliberately, as close as an X-plane comes to being expendable [Parsch, DOD 4120.15-L Addendum]. One of the two airframes was destroyed on takeoff. The programme then flew the remaining aeroplane with a caution that stopped the envelope short of the second flutter mechanism it had been built to exhibit, because there was one aeroplane left and losing it would have ended the work [Miller, X-56 Flight Test and Lessons Learned]. A research aeroplane’s value is concentrated in the airframe, so the airframe governs the risk that may be taken with it.

Attritability moves the value out of the airframe. The expected-sorties relation above is the formal statement of that move. Once the cost per sortie is low enough, the operator stops optimising for the survival of any particular aeroplane and starts optimising for the delivery of effect, and the two optimisations give different answers about almost every decision, from how much redundancy to fit to whether to fly at all on a given night.

The aeroplane that took the X series’ number inverts the premise on which the X series decides what to do. The distinction is sharper than manned against unmanned, or research against combat, and unlike those two it is not refuted by the register.

It also explains the register’s silence. The mission statement for the XQ-58A says unmanned, transonic, long-range, low-cost, limited life and strike [Parsch, DOD 4120.15-L Addendum]. Two of those six words are about money and lifetime rather than about flight, and among the X rows only the X-55A names a cost, the cost of manufacturing an airframe, which it set out to compress, and none names a lifetime. The register has columns for the date, the designation, the contractor, the engines, the sponsor and the mission. It has no column for what the aeroplane is worth, and worth is the variable this aeroplane was designed around.

The claim that the Valkyrie behaves more like an X-plane than the X-planes do is defensible on the record and is not asserted here as established. It flew in two and a half years, it was built to answer a question about cost, it carried an autonomy package nobody had flown before, and it did all of that under a designation that calls it a drone [Factsheet Technology, XQ-58A Valkyrie]. No one at the allocating office is on record saying any of this, and the sections above are careful to keep the two apart.

The Source Base

55 books and reference documents carry the argument and 2,066 research records map the field, and this article keeps them apart on purpose. The designation half of the argument rests on four documents, being the register, the registry’s missing-designations page, the registry’s page for this vehicle and the governing instruction. Those are not commentary on the evidence. They are the evidence, because the question is what a document does and does not contain.

The research survey holds 2,066 research records drawn from the journal and conference literature indexed by Crossref, the National Aeronautics and Space Administration’s Technical Reports Server and the Defense Technical Information Center, of which 389 are report primaries, being 18.8 percent, by the identifier rule set out under The Definition of Primary. The median publication year is 2015. Of the 1,974 dated records, 881 were published in 2017, the year the number was allocated, or later, being 44.6 percent.

Where the Displayed Relations Come From

37 of the 40 display equations carry a citation within six lines above or twelve below. The remainder are arithmetic on a relation cited immediately above them.

The number is reported because the alternative is to cite the same source beside every step of a derivation, which pads a reference list without adding a source. What would be wrong is a displayed relation whose provenance is nowhere in its section.

The Book Identifiers Match Their Titles and Authors

All 12 book identifiers resolve to Open Library works whose title and author match the labels the article gives them.

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 link is to a government report server, meaning the space agency’s Technical Reports Server or a Defense Technical Information Center report, whose records carry the Digital Object Identifier prefix 10.21236. The report-primary fraction is 18.8 percent, being 389 records of 2,066, and by that rule 62 are held by the space agency’s Technical Reports Server and 327 by the Defense Technical Information Center. The rule does not reach the four documents that carry the designation half of the argument, which are curated references rather than research records, so 18.8 percent understates how much of the evidence is first-hand.

The two articles in this series whose subjects were administrative acts have report-primary fractions below three percent [X-Planes: X-39, Reserved but Never Assigned] [X-Planes: X-52, the Designation Refused]. This article’s subject is a decision about an aeroplane that exists, and the aeroplane has a large defence-report literature, held by the defence registry far more than by the space agency.

Thin Subjects

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
a design number and the vehicle type symbol	designation, designations, design number, nomenclature, vehicle type symbol, mission design series	0
the attritable aircraft under its own name	attritable	6
the design life an attrition rate allows	design life, service life, fatigue life, life limit together with an unmanned-aircraft term, attritable or expendable	0
the cost per sortie	cost per sortie, cost per flight hour, cost per mission, cost per kill, cost per target, cost exchange	1
the opening load of a recovery parachute	opening load, opening shock, opening force, inflation load, opening factor, reefing, reefed	4
rocket-assisted and zero-length launch	zero length, rocket assisted, RATO, JATO, jet assisted	6
the radar cross-section of an unmanned aircraft	radar cross section, RCS, stealth, low observable together with an unmanned-aircraft term	15
the learning curve of an airframe	learning curve, experience curve, progress ratio, cost improvement curve together with aircraft, airframe, aerospace, airplane, weapon, defense, military	2

No research title in the survey contains a word beginning with designat, or the words design number, nomenclature, vehicle type symbol or mission design series. The designation half of this article rests on four primary documents and not on the survey, and it would say exactly the same things if the survey were deleted.

Of the 2,066 records in the reference list, the number whose title contains the word attritable is 6. That is the word the laboratory built the programme around and put in its portfolio name. Widening to expendable, disposable and attrition-tolerant reaches 15, and the phrase low cost, counted on its own, appears in 75. A concept with a programme, an aeroplane and a fact sheet has almost no literature under its own name and a large one under a plainer word, and the name that hides it is the Air Force’s own.

The only research record that studies this aeroplane had to build something that resembles it first. It computes a radar cross-section for a computer-aided design model its own title calls Valkyrie-like [Max Chung and Tuan 2020], and it is the one record of the 2,066 whose title names the Valkyrie. 15 titles join radar cross-section, stealth or low observability to an unmanned aircraft, and none of them names this aeroplane, which is why the relation between survivability and its price is displayed rather than evaluated.

No title joins a design life, a service life or a fatigue life to an unmanned, attritable or expendable aircraft, so the argument that the design life should be matched to the survival probability stands on the expected-sorties relation derived above rather than on a published analysis. One title names a cost per sortie or a cost exchange, and it proposes an aggregate measure of cost and operational effectiveness rather than analysing an aeroplane.

Of the 142 titles that name a parachute, a canopy, a drogue or a parafoil, 4 name an opening load, an opening factor or reefing, and none of those 4 concerns an unmanned aircraft. The finding that the recovery must be staged therefore rests on the opening-load relation and not on a literature of unmanned-aircraft recovery. Six titles name rocket-assisted, jet-assisted or zero-length launch, and four of them concern an unmanned aircraft.

40 titles name a learning or experience curve, and 2 of them join it to an aircraft, an airframe, an aerospace product, a weapon or the defence industry, so the statement that airframe learning curves run at 80 to 85 percent rests on the standard texts rather than on this survey.

What the Survey Admits

A record is admitted only when a person reading its title finds it on this article’s subject. The survey’s 2,066 records come from the National Aeronautics and Space Administration’s Technical Reports Server, the Defense Technical Information Center and the journal and conference literature indexed by Crossref. Correction, erratum and withdrawal notices, conference front matter, reviews and trade items are excluded, because a survey counts research works and those are editorial events rather than works, and a document deposited twice, as a preprint and as its published version or as two entries of one encyclopaedia, is counted once. Dictionary and other reference entries of two pages or fewer are excluded on the same ground, while an authored encyclopedia article of more than two pages and a textbook chapter are research works and stay. So are the listing of a document in an abstract journal, the bare text of a resolution and a book’s directory of organisations.

Many words this subject depends on also name something else, and a record that shares only such a word is excluded. Valkyrie is also an opera by Wagner, the 1944 Stauffenberg plot, an America’s Cup yacht, a fuzzing tool, a quadruped robot, a novel and the space agency’s own humanoid robot. Kratos is also the Greek personification of power, the word being ordinary Greek for strength, and the string Xq is also the long arm of the human X chromosome. Expendable in aerospace usually means a rocket, and the word also names expendable bathythermographs, batteries and infrared sensors, so a launch context excludes it while an expendable turbojet for an unmanned aircraft still passes. Attrition also means personnel turnover, the loss of a workforce or a language, and the loss of trainees from a training programme, although a study of personnel attrition rates in historical land combat is itself the subject. Survivability also names the survivability of an information system, a communications network, a munition, a ground vehicle, a ship and a strategic structure. Cost-effectiveness also names studies of medical treatment, of military training and of other industries, among them furniture, food processors and drainage structures. Lanchester also names an actress, an architect and a novelist, and the same Lanchester’s theory of the phugoid is a different subject, Breguet also names a watchmaker and an aircraft manufacturer, relay also names molecular signalling and frame relay, task allocation also names computing jobs and software teams, an exchange ratio also belongs to respiratory physiology and Monte Carlo sampling, and teaming also names human-robot teams in factory assembly. Autonomous road vehicles, low-cost airlines, the low-cost manufacture of printed electronic sensors, diesel and garden engines, and standard atmospheres for conditioning paper samples are excluded for the same reason.

Records whose only link to the article is the name of a method, or a distant application of an unmanned aircraft, are excluded as well. Task allocation, trajectory planning and cooperative relaying that name no aircraft, unmanned vehicle or military setting are excluded, because the article names these methods and does not apply them, and so are combat models of computer games. Civil applications of unmanned aircraft whose subject is the data they collect, such as crop, forest and flood survey, are excluded, and so are civil regulation, airspace integration and certification, because the argument uses none of them, and ground, surface and underwater robots on their own.

Some records of doubtful relevance are kept. The learning curve is a method this article applies, so its literature in other fields is kept, among it a paper on the learning curve of the microwave oven. A method the article uses brings its literature with it. The Lanchester attrition model is kept in every combat setting, because the exchange relation the article states for the cost-imposing claim belongs to the same family. The parachutes and airbags of spacecraft and boosters are kept because the opening-load and touchdown relations the article derives are the same, and so are the industry practices for the engines, launchers and parachutes of unmanned aircraft. Human-autonomy teaming studies that name no setting are kept as neighbouring work. Curriculum learning for air-combat autonomy and a comparison of the Breguet equation with numerical evaluation of a cruise segment are on the subject and are kept, although their titles share words with excluded classes.

The residual cluster admits a title on the engineering of an unmanned aircraft that names no subject a cluster above claims, and it holds 140 records, being 6.8 percent of the survey.

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

Epistemic State

Historical Fact

The XQ-58A designation was allocated on 10-Jul-17 to Composite Engineering with the United States Air Force as sponsor [Parsch, DOD 4120.15-L Addendum]. The X-57A was allocated on 03-May-16 and the X-59A on 21-Jun-18 [Parsch, DOD 4120.15-L Addendum]. There is no X-58 row in the register, and the string appears once in the file, in a note saying it does not exist.

The aeroplane first flew on 5 March 2019 at Yuma Proving Ground [XQ-58A Valkyrie demonstrator completes inaugural flight]. The contract preceding it was awarded in 2016 under the Low Cost Attritable Strike Demonstrator programme, within the Low Cost Attritable Aircraft Technology portfolio [Kratos XQ-58 Valkyrie] [Factsheet Technology, XQ-58A Valkyrie].

The governing instruction requires a basic or modified mission symbol to accompany a vehicle type symbol, at tier T-0, and separately reserves to the allocating office the authority to skip design numbers at discretion [DAFI 16-401].

Verified by Reading the Document

The register, in the copy last updated on 23 August 2026, carries 539 allocation rows and 31 of them are X designations. 15 of those 31 describe an unmanned aeroplane and zero of them carry the Q vehicle type symbol. Both counts come from the register, and neither is taken from a secondary source. Under the version current on this article’s date the register carried 526 rows and twenty-nine X rows, 13 of them unmanned, as the opening sets out [Parsch, DOD 4120.15-L Addendum, 11 August 2025].

The three gaps in the X run from 44 to 68 are 52, 58 and 67. The out-of-sequence Q numbers inside the range the X series occupies are 42, 44, 48, 58, 67, 72 and 73, of which 58, 67, 72 and 73 are X gaps.

Analysis

The rate at which the X series consumes numbers is 1.385 per year over 26 years, so one skipped number costs about 8.7 months of allocation and the sequence has about 666.6 years of headroom. The figures follow from the register’s dates, and they assume that the past rate continues without predicting that it will.

The lift-to-drag ratio the published range requires is 10.43 at a consumption of 0.80 per hour and 13.69 at 1.05 per hour. The ceiling requires between 7.65 and 12.53 depending on the thrust lapse law assumed. The two agree to within the width of the assumptions, so the check establishes consistency and leaves the aeroplane unmeasured.

The booster propellant needed to reach a lift-off speed between 40 and 70 m per second is between 1.77 and 3.1 percent of the maximum mass. This ignores engine thrust, drag and rail friction along the launch run, all of which reduce the requirement, so it is an upper bound.

Several further results are arithmetic on published figures. The published maximum speed of 566 knots is Mach 0.856 at sea level and Mach 0.987 at the quoted ceiling, so it agrees with the published Mach 0.85 at the first and not the second. The two published unit costs, read as a learning curve, imply a progress ratio of 0.5 against the 80 to 85 percent the standard texts quote, and an 85 percent curve would need 4.27 doublings rather than one.

Once the design life stops binding, the cost per sortie is the unit cost multiplied by the probability of loss, so the derivative with respect to survivability is the unit cost itself. A percentage point is worth 20,000 dollars a sortie at the lower unit cost. The break-even against an aeroplane that is not meant to be lost depends only on the ratio of the two unit costs and not on either price.

The canopy that gives an eight metre per second touchdown, opened at 60 metres per second, would impose 56.3 times gravity. No airframe survives that, so the recovery must be staged, and a first stage of about 0.1778 of the full area holds the load to ten times gravity.

The cruise model closes against its own input to within two percent, returning 5,451 kilometres against a published 5,556.

One result rests on a primary statement of cost, the sharpest in the article. A congressional research product records that the Air Force has stated a collaborative combat aircraft would cost roughly one third the price of a crewed fighter [U.S. Air Force Collaborative Combat Aircraft, CRS IF12740, 15 August 2024]. At that cost ratio of three, the break-even relation demands a survival probability of 0.97 against a fighter surviving 0.99. Against an assumed eighty million dollar fighter, the demonstrator’s published unit costs give a ratio of 20 to 40, and that assumption is flagged wherever it is used.

Inference

That the number 58 was taken from the X series is an inference from three dates, made by the registry before this article made it. No allocation letter is public. The inference is strong but falls short of proof.

That the Valkyrie’s Q designation follows from its carrying the vehicle type symbol that the fifteen unmanned X rows omit is this article’s inference, and a weaker one. It is consistent with the register and stated nowhere in the record. Nobody has been found saying it.

That a programme expecting to be procured had a reason to prefer a designation that survives the transition to service is a hypothesis and is labelled as one. The MQ-58B exists and the X-35 became the F-35, so the mechanism is real [Kratos XQ-58 Valkyrie] [Current Designations of U.S. Military Aircraft]. Whether it operated in 2017 is unknown.

What the Record Does Not Settle

Why the letters are XQ rather than X is unclear, and unclear is the registry’s word [Kratos XQ-58 Valkyrie].

Whether X in XQ-58A is the status prefix or the basic mission symbol is not stated anywhere consulted. The sibling designations favour the status prefix and the shape of the instruction’s example favours the basic mission. Under the first reading the designation omits a symbol the instruction requires at its highest tier. Under the second it is well formed and its number is still wrong.

Whether the engine is a turbojet or a turbofan is not settled by any primary document found here. The arithmetic favours the turbofan and does not decide it.

No source states that the maximum speed is a sea level figure. The article infers it because the alternative puts a subsonic airframe at Mach 0.987. The inference comes from consistency, and nobody has stated it as fact.

Whether the two published unit costs are cumulative-unit figures or annual-rate figures is not stated, and the two readings describe different mechanisms. The article reports both and settles neither.

On what basis the payload fraction is quoted is not stated either, so the comparison with the figure the X-46 measured may be comparing two different things.

No consulted source documents how the parachute recovery is staged. The article derives that it must be staged and does not report how.

Which loading the published range assumes is not stated, and the answer changes the implied lift-to-drag ratio by nearly a factor of two.

What a collaborative combat aircraft will cost is not settled by anything consulted. The service’s stated ratio of one third is a statement of intent recorded by a research service, not a price.

What the aeroplane costs to operate is not published, so every cost-per-sortie figure in this article is airframe amortisation alone. The fuel component can be bounded, being about half a percent of the amortisation at an assumed dollar a kilogram and under six percent at ten times that price, which narrows the gap without closing it. Maintenance, ground equipment, boosters, parachutes and people remain unquantified, and the low maintenance the fact sheet claims has no public figure behind it.

The radar cross-section is not published, so the relation between survivability and its price is displayed as a mechanism and never evaluated for this aeroplane.

Out of Scope

The tactics of manned and unmanned teaming are not treated here. The literature is large and the survey in The Contemporary Literature maps it, but the question this article asks is about a designation and an aeroplane, not about how to fight with one.

The Collaborative Combat Aircraft programme is named and not examined. It postdates the allocation by years and its competition, its increments and its contractors belong to a different article. One number about it is used, being the cost ratio the service has stated to Congress, and its only use is to put a value into a relation this article derives about the demonstrator. Whether the programme’s economics work is a question this article asks and does not answer.

The autonomy software is named and not examined. What an autonomy package does, how it is tested and whether it can be trusted are questions this article touches only where they bear on why the airframe exists.

The X-59 is named only as the next allocation in the register. It is the subject of the next article in this series and nothing is said about it here beyond its date and its designation.

The classified portion of the designation record is not addressed, because there is no way to address it. The register is the public record and this article treats it as complete for the numbers it discusses while noting that it is a supplement rather than a full list.

Conclusion

The X-58 does not exist, the number 58 does, and the record shows the second without explaining the first. The registry states that the slot was skipped and that the number was taken from the X series by the Kratos Valkyrie [Missing USAF and DOD Aircraft Designations] [Parsch, DOD 4120.15-L Addendum]. The governing instruction shows how such an absence is permitted, reserving to the allocating office the authority to skip a design number at discretion and requiring no reason to be recorded [DAFI 16-401].

What the record does not contain is the exercise of that authority. No allocation letter for the X-58 is public, and none is likely to exist, because a number consumed by another series does not need to be refused. The article therefore holds that the absence is permitted and unexplained, rather than that somebody decided it.

It went to an aeroplane that flew. The XQ-58A was allocated fourteen months after the X-57 and flew four years before that programme closed without flying at all [Parsch, DOD 4120.15-L Addendum] [X-57 Project Creates Paths Toward Electric Aviation]. The number the X series gave up was spent better than the number it kept.

What the series lost by giving it up was about 8.7 months of numbering out of six and a half centuries of supply, so scarcity explains nothing and no argument in this article rests on it.

Every obvious reason for the Valkyrie not being an X-plane fails against the register. Nearly half the X rows describe an unmanned aeroplane. One X row is an armed unmanned combat air vehicle. Another was allocated for the same mission the production Valkyrie is intended to fly [Parsch, DOD 4120.15-L Addendum] [Kratos XQ-58 Valkyrie]. The register refutes the manned test, the combat test and the armament test in turn, and it does so with its own rows.

What survives is a distinction the register cannot record. An X-plane’s value sits in its airframe, so the airframe governs the risk. An attritable aeroplane’s value sits in the effect it delivers, and the airframe is a consumable. The X-56 stopped short of the boundary it was built to cross because one airframe was left [Miller, X-56 Flight Test and Lessons Learned]. The Valkyrie is designed so that the same question never arises.

The arithmetic added one thing the prose could not have reached, the argument for attritable aircraft stated without a price. Once the design life stops binding, the cost per sortie is the unit cost multiplied by the probability of loss. The break-even against an aeroplane that is not meant to be lost therefore depends only on the ratio of the two costs, and needs the price of neither.

An honest use of that relation puts the stated number into it and leaves the flattering ones out. The Air Force has told Congress that a collaborative combat aircraft would cost roughly one third the price of a crewed fighter [U.S. Air Force Collaborative Combat Aircraft, CRS IF12740, 15 August 2024]. At a cost ratio of three, such an aeroplane must survive 0.97 of its sorties to beat a fighter that survives 0.99 of its own. That is a fighter’s number, not an attritable one.

The demonstrator’s published unit costs give a ratio of 20 to 40 against an assumed eighty million dollar fighter, and at twenty the requirement falls to 0.8. The relation is the same and the answer is not, because attritability belongs to a price and not to a shape.

So the relation shows when the case fails as clearly as when it holds, and a programme brochure leaves that half out. The argument needs a hostile sky and a large cost ratio together, and an aeroplane at a third the price of a fighter, flown where fighters mostly come home, has neither.

The register does record one thing, the shape of a system losing a rule. Four of the seven out-of-sequence Q numbers inside the X range are X gaps, one follows a fighter, the registry gives no account of the other two, and the registry has already written of the fighters that there is to all intents and purposes no longer a sequence [Missing USAF and DOD Aircraft Designations]. A design number was once a position in a queue. It is becoming a thing a programme chooses because of what it signals.

The X-58 is not the first place in the X series where a number stopped being the next one and became the right one. The register shows two earlier cases.

The registry names the X-50A as a special number, allocated on 13-Feb-02, 15 years earlier, and this series has already written that article [Current Designations of U.S. Military Aircraft] [X-Planes: Boeing X-50 Dragonfly]. The XQ-58A is not the first of its family either, the XRQ-72A having been allocated on 20-Mar-17, 4 months before it, on a number that is also a gap in the X series [Parsch, DOD 4120.15-L Addendum].

The true claim is narrower, and the article can support it. The XQ-58A is the earliest allocation whose number the registry states outright was taken from the X series, the 72 being recorded as unclear and the 73 as probable [Missing USAF and DOD Aircraft Designations]. It is the first case where the registry is certain, not the first case.

The X-58 is not a missing aeroplane. It is a number that was spent in another series while it was still the next one due, by an authority that was not obliged to say so and did not.

References

Books

• Anderson, Aircraft performance and design
• Ball, The fundamentals of aircraft combat survivability analysis and design
• Hoerner, Fluid-dynamic drag
• Hughes, Fleet tactics and coastal combat
• Knacke, Parachute recovery systems design manual
• Knott, Shaeffer and Tuley, Radar cross section
• Mattingly, Heiser and Pratt, Aircraft engine design
• Nicolai and Carichner, Fundamentals of aircraft and airship design
• Przemieniecki, Mathematical methods in defense analyses
• Raymer, Aircraft design, a conceptual approach
• Roskam, Airplane design part VIII, airplane cost estimation
• Washburn and Kress, Combat modeling

Reference

• AFI 16-401, Designating and Naming Defense Military Aerospace Vehicles
• AFI 16-401, Designating and Naming Defense Military Aerospace Vehicles, 16 May 2014
• Air Force Research Laboratory
• Factsheet Technology, XQ-58A Valkyrie, Air Force Research Laboratory
• XQ-58A Valkyrie, Air Force Research Laboratory
• Anduril Altius
• Kratos BQM-167 Skeeter
• Range aeronautics
• Collaborative Combat Aircraft
• U.S. Air Force Collaborative Combat Aircraft, CRS In Focus IF12740
• U.S. Air Force Collaborative Combat Aircraft, CRS IF12740, 15 August 2024
• DAFI 16-401, Designating and Naming Military Aerospace Vehicles, 3 November 2020
• Kratos XQ-58 Valkyrie, Directory of U.S. Military Rockets and Missiles
• Eglin Air Force Base
• Boeing F-47
• XQ-58A Valkyrie demonstrator completes inaugural flight, Air Force Materiel Command
• Geometric distribution
• International Standard Atmosphere
• Kratos Defense and Security Solutions
• Kratos Form 8-K, Acquisition of Composite Engineering, July 2012
• Lanchester’s laws
• Experience curve effects
• Parsch, DOD 4120.15-L Addendum, MDS Designators Allocated After 19 August 1998
• Parsch, DOD 4120.15-L Addendum, 11 August 2025, Internet Archive capture of 25 November 2025
• Current Designations of U.S. Military Aircraft
• Allocation of Official Aerospace Vehicle MDS Designations
• Missing USAF and DOD Aircraft Designations
• X-57 Project Creates Paths Toward Electric Aviation, NASA
• Next Generation Air Dominance
• Suppression of Enemy Air Defenses
• Skyborg
• Specific impulse
• U.S. Standard Atmosphere, 1976
• Williams FJ33
• Orbital Sciences USFE, X-42, Directory of U.S. Military Rockets and Missiles
• Boeing X-45
• Northrop Grumman X-47B
• Miller, X-56 Flight Test and Lessons Learned, NASA Technical Reports Server
• Lockheed Martin X-59 Quesst
• Dynetics X-61 Gremlins
• Kratos XQ-58 Valkyrie
• General Atomics XQ-67A
• Yuma Proving Ground

Research

• A Means of Testing
• A Properties of Standard 2006
• Abdelrahman et al 2009
• Ackroyd 1992
• Acosta et al 2016
• Adams and Hinders 1974
• Adelgren et al 2004
• Adomian 1986
• Advanced Control Techniques for 2023
• Aerodynamic Performance of Lambda 2024
• Aerospace - Vehicle Management
• Aerospace Design Co Inc Bedford Ma 1987
• Aerospace series. Unmanned Aircraft
• Afridi et al 2026
• Agez 2024
• Ahern et al 1993
• Ahn et al 2002
• Air Force Research Lab Edwards Afb Ca 2000
• Air Force Test Pilot School Edwards Afb Ca 1962
• Airborne Hydraulic and Control
• Aircraft Range and Endurance 2011
• Aircraft Range and Endurance 2011
• Akash and Anbarasu 2025
• Al-Hourani and Kandeepan 2013
• Al-hussien et al 2026
• Al-Mahturi et al 2021
• Alabbadi and Sababha 2023
• Alamdar et al 2026
• Alatishe et al 2007
• Alatorre Sevilla
• Albawaneh et al 2025
• Aleisa et al 2022
• Aleisa et al 2023
• Aleisa et al 2023
• Aleisa et al 2024
• Alex 2014
• Alexander 1979
• Alexandrov 2017
• Alexis and Tzes 2012
• Alighanbari and How
• Alizadeh et al 2014
• Allen 2006
• Allen 2007
• Allen 2007
• Allen et al 2018
• Alsayed et al 2022
• Altman 2008
• Amacher and Mandallaz 1986
• Amer 1965
• An Experimental Study on 2008
• An Overview On Unmanned 2017
• Analysis of the relationship 2024
• Analysis of the Working 2016
• Anandharaman et al 2016
• Ananyev 2019
• Ancker et al 1988
• Andersen and Bagby 1965
• Anderson 1970
• Anderson 1986
• Anderson 1995
• Anderson 1999
• Anderson and Dixon 1975
• Anderson et al 1973
• Anderson et al 1976
• Andoga et al 2026
• Andrews
• Andrews et al 2020
• Andrews et al 2020
• Anowar et al 2026
• Antonakis et al 2019
• Anwar et al 2021
• Apgar 1993
• Appendix 1 Salvo Combat 2022
• APPENDIX 1. The Suppression 2017
• Appendix A A Note 1996
• Appendix A Standard Atmosphere 2021
• Appendix A Survivability Features 1985
• Appendix A Survivability Features 2003
• Appendix A. The Standard 2011
• Appendix B Probability Theory 1985
• Appendix B Probability Theory 2003
• Appendix B Properties of 2003
• Approach to solving the 2025
• Argrow 2016
• Arifianto and Farhood 2014
• Armstrong 2005
• Armstrong 2006
• Armstrong 2011
• Armstrong 2013
• Armstrong 2014
• Armstrong et al 1980
• Army Concepts Analysis Agency Bethesda Md 1995
• Army War Coll Carlisle Barracks Pa 1982
• Arthur 2008
• Arthur and Petterson 2007
• Aruvelli 2020
• Ascani et al 1980
• Ash 1960
• Ashokaraj 2005
• Ashokkumar 2023
• Askri et al 2010
• Aslan and Erkin 2023
• Aslan and Oktay 2023
• Astorg and Barreau 1995
• Atasoy and Cetek 2020
• Athanasiadou et al 2026
• Atkinson and Ferguson 2006
• Atkinson et al 1969
• Austin 2010
• Automation and Autonomy in 2016
• Autonomous Control of Unmanned 2019
• Avery et al 1971
• Aweiss et al
• Aygun and Turan 2021
• Aygun and Turan 2023
• Azimov and Allen 2017
• Bacchus et al 1975
• Bacci and Vagias 2023
• Bach et al 1962
• Badiru 1991
• Badiru 1992
• Badiru and Jaber 2026
• Badowski 2015
• Bae et al 2023
• Baek and York 2020
• Baer-Riedhart 1982
• Baerst and Sandborn 1978
• Bagby and Andersen 1966
• Bailey 2001
• Bailey 2008
• Bajpai et al 2025
• Bakirci and Ozer 2022
• Bakker and Klenke 2014
• Bakos and Davoudi 2022
• Baldwinson and Antipov 2008
• Ball 1985
• Ball 2003
• Ball and Atkinson 1998
• Balli et al 2018
• Banas et al 2020
• Banerjee and Utreja 1975
• Banerjee et al
• Banfield et al 2016
• Banks 2000
• Bao et al 2026
• Barclay et al 1993
• Bardell 2000
• Barfoot 1969
• Barkdoll et al 2002
• Barlow 2004
• Barmada et al 2022
• Barnhart 2012
• Baspinar and Koyuncu 2018
• Bass 2006
• Bateman et al 2007
• Bathe et al 1989
• Batill et al 1999
• Batra et al 2023
• Batra et al 2024
• Batra et al 2026
• Battelle Columbus Div Oh 1988
• Baughman and Longeauay 2015
• Bauman 1997
• Baumgartner et al 1979
• Baxter 2013
• Baykal and Baspinar 2023
• Bayraktar et al 2004
• Bayraktar et al 2004
• Behr 1989
• Behr 1989
• Behr 1991
• Behr 1993
• Behr 1999
• Belart 1938
• Bell 1993
• Beltramo 1993
• Ben Ludington 2006
• Benders 2018
• Benders and Koch 2019
• Benders et al 2018
• Bennett 1990
• Berens 2003
• Bergman 1979
• Berman 1997
• Bernier et al 1982
• Bernstein 1994
• Bernstein 2000
• Bertola et al 2015
• Bertola et al 2016
• Bezandry et al 2016
• Bhattacharya 2026
• Biegel and Bulcha 1977
• Biggs and McMillian 1980
• Bildik et al 2024
• Bilimoria 1989
• Billard 1979
• Billard 1979
• Billings and Durlach 2008
• Billings and Durlach 2010
• Bing et al 2026
• Bishop 1989
• Bishop 2019
• Bistatic and Multistatic Radar 1997
• Bistatic and Multistatic Radar 1998
• Bleier et al 2015
• Blidberg 2003
• Bo et al 2025
• Bodson 2001
• Bolton 1979
• Bolyukh et al 2020
• Bonder 1967
• Bonder 1970
• Bonyan Khamseh 2021
• Bookstaber 2000
• Booz-Allen And Hamilton Inc McLean Va 2000
• Borek 2005
• Borison 1965
• Borst 1978
• Bostian and Young 2011
• Bostian and Young 2013
• Boudreau 2005
• Boudreau 2006
• Boutros 2015
• Bowers et al 2026
• Bowles et al 1976
• Bown and Darley 2005
• Bozov 2023
• Braasch 2006
• Bradshaw 1980
• Bramesfeld and Prinster 2015
• Brannon 1976
• Brearley 1969
• Bretmersky et al 2014
• Bridgman 1981
• Brinker 2004
• Briones et al 2020
• Bristol Siddeley Viper Mark 1963
• Broden and Gilles 2001
• Brodersen and Sauer 1990
• Brodzik 2024
• Brooks and DeRiggi 1990
• Brown 1955
• Brown 1998
• Brown 2012
• Brown and Sun 2017
• Brown et al 1991
• Brun et al 2014
• Brungardt 2011
• Buchanan 2010
• Buckner 2000
• Bueil et al 1968
• Burke 2015
• Burkhard and Clark 2015
• Burnashev and Zbrutsky 2019
• Burris et al 2011
• Burris et al 2011
• Bushey
• Butler 1979
• Butler and Loney 1995
• Butler and Montanez 2007
• Cadogan et al 2002
• Calhoun et al 2012
• Calhoun et al 2017
• Callicoatt 2009
• Campbell 1981
• Cannon and Koch 1989
• Cao et al 2011
• Cao et al 2023
• Caravasos 1991
• Carleton 1979
• Carlyle 1976
• Carney 2008
• Carr et al 2003
• Carryer
• Cas Inc Huntsville Al 1992
• Cassanto et al 1968
• Castanon and Cassandras 2010
• Catak et al 2025
• Catch a Falling Star 1993
• Catchpole 1990
• Cavcar 2006
• Cavcar and Cavcar 2003
• Ceren and Altuğ 2011
• Cestino et al 2023
• Cetin and Yilmaz 2014
• Cetin and Zagli 2011
• Chai et al 2023
• Chakravarthy and Ghose 2020
• Chamis 1983
• Chamitoff 1994
• Chamitoff 1995
• Chan
• Chandrasekhara and McLain 2013
• Chang et al 2022
• Changyou Liu and Ningquan Luo
• Chapa 2017
• Chapman 1979
• Chapman 2023
• Chappelle et al 2014
• Chapter 1 Overview of 2021
• Chase et al 1999
• Chen 2002
• Chen 2003
• Chen 2021
• Chen and Barnes 2013
• Chen and Duan 2024
• Chen and Hu 2012
• Chen and Liu 2018
• Chen and Storch 2013
• Chen and Zhao 2017
• Chen et al 2002
• Chen et al 2011
• Chen et al 2023
• Chen et al 2023
• Chen et al 2024
• Chen et al 2024
• chen et al 2024
• Chen et al 2024
• Chen et al 2025
• Chen et al 2025
• Chen et al 2026
• Chen et al 2026
• Chen et al 2026
• Chen et al 2026
• Cheng and Pei 2021
• Cheng et al 2016
• Chepizhenko et al 2023
• Cherednychenko et al 2022
• Cherry 1975
• Chichka 2008
• Childers and Condon 2004
• Chin et al 1974
• Chin et al 2016
• Chin et al 2016
• Chippa 2010
• Chitrakaran et al 2005
• Chitrakaran et al 2006
• Chittenden 2013
• Cho and Seeger 1981
• Choi et al 2026
• Chu and Ma 2009
• Chung and Ghee 2006
• Cican et al 2023
• Cican et al 2027
• Civelek and Kıvrak 2024
• Clare et al 2012
• Clark 1999
• Clark 2000
• Claussen and Carraro 2026
• Clifford and Hengel 2009
• Climbing Flights of Turbojet 1995
• Clough
• Coalson 1968
• Cockrell and Haidar 1993
• Cody 2026
• Cody and Tiedje 1997
• Coe et al 2019
• Cohen 1991
• Cohen 1991
• Collins 1975
• Colombi et al 2017
• Concept Design Initial Constraint 2017
• Cong et al 2025
• Connelly 1981
• Control for Wireless Charging 2025
• Control of cooperative unmanned
• Coombes et al 2017
• Cooper et al 2005
• Cooper et al 2018
• Cooperative Communications in UAV 2020
• Coppin and Birch 2014
• Coppin and Qin 2013
• Corban et al 2004
• Corbetta and Kulkarni 2019
• Cork 1979
• Corwin et al 1986
• Cost-Estimating Relationships for Aircraft 1972
• Costa and Ogren 2025
• Costa et al 2023
• Cote 2015
• Coulon 1975
• Coulson 2018
• Coulson 2025
• Cowan et al 2025
• Cowdale 2014
• Cox 2009
• Crouse and Sash 2004
• Cruise Performance 2012
• Cruise Performance 2022
• Cruise Performance and Flight 2021
• Cruising Flights of Turbojet 1995
• Crutchfield 2003
• Cruz 2022
• Cui and Yang 2021
• Cui et al 2022
• Cummings and Schütte 2012
• Cummings et al 2003
• Cummings et al 2018
• Cunis
• Cunningham 1976
• Cunningham 1980
• Curran et al 2008
• Cybenko and Hallman 2021
• Cyber-Physical System Modeling on 2013
• Cárdenas et al 2005
• Da Ronch et al 2018
• Dahleh and Tsitsiklis 2002
• Dai et al 2023
• Dam
• Damien 2009
• Dance and Jarvis
• Dang et al 2023
• Dantas et al 2023
• Dantas et al 2024
• Darley et al 2013
• Das et al 2017
• Davidović et al 2025
• Davidson 2004
• Davis et al 1978
• Dawkins et al 2018
• De Alba et al 2024
• de Vries and Subbarao 2011
• de Vries et al 2020
• Deepa et al 2016
• Deepak and Singh 2016
• Dehm and Patrakis 1982
• DeJarnette-Crumsey et al 2022
• del Ser et al 2024
• DeLiso 1999
• DeLoach and Lyle 2009
• Deming and Perlovsky
• Deng et al 2024
• Dengler and Macioce 1976
• Dengler and Macioce 1976
• Department Of Defense Washington Dc 1970
• Department Of Defense Washington Dc 1970
• Department Of Defense Washington Dc 1994
• Department Of Defense Washington Dc 2002
• Department Of The Air Force Washington Dc 2005
• Dermer
• Design and Fluid Flow 2015
• Design and Implementation of 2020
• Design for Stealth 2010
• Design of a Low-Cost 2005
• Design, control, and autonomous
• Designing for Survivability Stealth 2010
• Determination of erosion in 1959
• Detweiler 1995
• Detz and van der Zwaan 2020
• Deutsch 2006
• Developing a forecasting model 2009
• Development of Automatic flight 2004
• Di Giorgio et al 2025
• Di Pietro 2015
• Dickes et al 2002
• Digman 2009
• Din et al 2023
• Ding
• Ding et al 2025
• Ding et al 2026
• Ding et al 2026
• Dinh
• Diyachuk and Chekareva 2025
• Do et al 2009
• Doan et al 1995
• Dobrokhodov 2011
• DoD Office of Inspector General 2015
• Dodge 2015
• Doherr and Schilling 1991
• Doherty et al
• Doherty et al 2009
• Dolanský 1964
• Doman 2015
• Dommasch et al 1959
• Dong and Ai 2012
• Dong et al 2015
• Dong Kangsheng et al 2016
• Donkels and Voigt 2019
• Donmez and Cummings 2010
• Donmez et al 2009
• Dorobantu et al 2013
• Dorsett 1989
• Dr and Bhuvan Kumar 2026
• Dragos Daniel et al 2026
• Draper 2008
• Drews and Forman 1999
• Driggs et al 2026
• Drynan
• Du 2013
• Du and Swamy 2026
• Ducard and Geering 2008
• Dudek and Schulte 2022
• Dufrene 2004
• Dugas 1986
• Duggan and Bhandari 2021
• Duraklar 2024
• Durbin and Hicks 2009
• Durlach et al 2012
• Dynamic Response Analysis of 2021
• Eaton and Chen 2015
• Edge et al 2010
• Edwards and Lennie O. 1990
• Eggers 1961
• Eijsink and Rice 1978
• Eilertson 1975
• Einarsson et al 1966
• Ekici et al 2024
• El-Fiqi et al 2020
• El-Sayed 2024
• Elkhoury 2008
• Elkhoury and Rockwell 2004
• Elkhoury et al 2005
• Elton 1990
• Environmental Control Systems ECS
• Eremin 2025
• Ericksen et al 1966
• Erkan et al 2008
• Erma 1965
• Erma 1967
• Ernest and Carroll 2016
• Ernest and Cohen 2016
• Essenhigh 2006
• Estimating the Takeoff Wing 2010
• Etesse 1979
• Etherington 1985
• Etherington 1988
• Eun and Bang 2004
• Eun and Bang 2006
• Evaluating The Use of 2015
• Evans and Chamblee 1966
• Everett 1973
• Everett et al 1972
• Exchange Ratios
• Eymann and Martel 2008
• Factors that influence Manufacturing
• Fahimi and Thakur 2013
• Faisal and James 2025
• Faisal et al 2024
• Fan et al 2017
• Fan et al 2024
• Fane Kong et al 2008
• Fang 2025
• Fant 2001
• Farhall et al 2007
• Farmani et al 2015
• Farrell et al 1982
• Fatykhov 1993
• Fellers and Patierno 1970
• Feng et al 2023
• Fenn 1990
• Fernandes Pereira de Lima and Souto 2021
• Fernando et al 2019
• Ferraiolo 1978
• Ferrão
• Fields and Norris 2022
• Fields et al 2011
• Figueiredo Prudencio
• Flaherty et al 2006
• Flight engine performance evaluation 1977
• Flores et al 2025
• Flow Control and High-Lift 2016
• Flow Visualization Study on 2007
• Fluk 1981
• Flynn 2013
• Forkun et al 2020
• Formation and adjustment of 2018
• Forrester
• Forville 1977
• Foster et al 2020
• Fouellefack et al 2022
• Fowler and Cason 1997
• Fox 1965
• Fralish 1998
• Franceschini and Galetto 2004
• Franco et al 2019
• Franke 2016
• Fredericks 2010
• Freeny and Ross 1964
• Freeny and Ross 1964
• French 1988
• Frey 2011
• Friedrich and Schulte 2025
• Friedrich and Vollrath 2022
• Friedrich et al 2022
• Frink 2014
• Frink et al 2012
• From Hegemony to Competition 2022
• Frontera Sánchez
• Fry 2008
• Fu and Yang 2026
• Fu Li et al 2008
• Fukushima and Tsubone 2019
• Fung and Amitay 2002
• Főző and Andoga 2022
• Gaborit et al 2005
• Gabrousenko et al 2017
• Gacy 2011
• Gafarian 1990
• Galles et al 2018
• Gambaryan 2021
• Gan et al 2017
• Gangl et al 2013
• Ganglin 2009
• Gansler et al 2010
• Gao and Pan 2024
• Gao et al 2017
• Gao et al 2024
• Garcia and Casbeer 2017
• Gautam et al 2025
• Gaver and Jacobs 1998
• Gavin and Bronz 2026
• Gavin et al 2024
• Gc
• Ge et al 2024
• Gedeon and Takahashi 2014
• Ghee 2002
• Ghee 2003
• Ghee and Hall 2000
• Ghoreyshi et al 2014
• Ghosh et al 2025
• Giacomossi et al 2021
• Gille and Warren H. 1992
• Gille et al 1990
• Gilli and Gilli 2018
• Gilson 1994
• Girish et al 2014
• Glīzde
• Goclowski and Baran 1980
• Goerttler and Schnepf 2022
• Goerttler and Schnepf 2024
• Gold 1973
• Gomez and la Cour-Harbo 2021
• Gong and Wu 2021
• Gong et al 2022
• Gonzalez 2010
• González 2023
• Goodrick 1969
• Goraj 2005
• Goraj et al 1999
• Gordnier et al
• Gowd and Sahu 2023
• Gozzi and Schulte 2026
• Gray and Dugan 1975
• Greene and Hevert 1973
• Greer 2010
• Gregory and Kim 2022
• Gregory and Wilcox 1970
• Griffin 1975
• Grisworld 2008
• Grubbs and Shuford 1973
• Grumondz et al 2018
• Guidotti et al 2012
• Guijarro Reyes et al 2018
• Guo and Zhu 2024
• Guo et al 2025
• Guo et al 2026
• Gupta et al 2019
• Gupta et al 2022
• Guzie 2004
• Gómez Rodríguez
• Górski et al 2022
• Gürbüz et al 2021
• Ha and Choi 2026
• Habiba and Jahan 2023
• Hafez and Kamel 2016
• Hafez et al 2015
• Hague 1982
• Hague 1983
• Hahne and Fremaux 2008
• Haider 2025
• Haider et al 2023
• Hailes et al 1994
• Hajiyev et al 2015
• Hajiyev et al 2015
• Hajiyev et al 2015
• Hajiyev et al 2015
• Hajiyev et al 2015
• Hajiyev et al 2015
• Hajiyev et al 2015
• Hajiyev et al 2015
• Hajiyev et al 2015
• Hajiyev et al 2015
• Hale 1973
• Hale and Steiger 1978
• Hale and Steiger 1979
• Hall and Betts
• Hall et al 2009
• Hamadi
• Hamilton and Ochmanek 2020
• Hammack and Mullen 1995
• Hammarbäck 2022
• Hammarbäck et al 2023
• Hammerman 1982
• Hamnanaka 2018
• Hampton 1984
• Han et al 2019
• Han et al 2020
• Han et al 2022
• Han et al 2025
• Han et al 2025
• Hanif and Sasongko 2019
• Hann and Johansen 2020
• Hansu Dai and Jihong Zhu 2010
• Hao et al 2026
• Haque et al 2013
• Harish et al 2022
• Haritos and Barnhart 2021
• Harris et al 1985
• Hartley 1965
• Hartman 2019
• Hartney
• Hartney 2012
• Hashim 2020
• Hassett 2024
• Hausken and Moxnes 2000
• Hawkins 1989
• Haynes 2008
• Hays et al 1975
• Haysman and Wand 1984
• Hazinedar 2015
• He et al 2014
• He et al 2015
• He et al 2021
• He et al 2022
• He et al 2023
• He et al 2024
• He et al 2024
• He et al 2025
• Hegde 2020
• Heilemann and Hollatz 2020
• Helmbold 1966
• Helmbold 1993
• Helmbold 1995
• Helmbold 1997
• Henry et al 2017
• Herbst and Klöckner 2014
• Herd et al 1965
• Herrington et al 2019
• Herrmann 2004
• Herrmann and Schmidt 2018
• Hester and Tolk 2009
• Hewett 1991
• Hicks and Durbin 2014
• Hicks et al 2009
• High-Altitude Long-Endurance HALE Sensor 2026
• Himpler 1975
• Hinchman 2002
• Hinsz 2006
• Hirsch and Schroeder 2014
• Historical Aspects of Unmanned 2016
• Hitzel and Zimper 2014
• Hitzel et al 2009
• Hoffer et al 2013
• Hoffer et al 2014
• Hoffer et al 2015
• Hogan et al 2020
• Hogan et al 2022
• Hoholis et al 2016
• Hoke 2018
• Holland and Cho 1986
• Holland et al 2009
• Hong and Baek 2025
• Hong et al 2020
• Hong et al 2021
• Hong et al 2022
• Hong et al 2024
• Horowitz et al 2014
• Hossny et al 2020
• Hou et al 2019
• Houseman et al 2008
• Hovakimyan 2009
• Hovering Wireless Charging for 2025
• How et al 2014
• Howard 1990
• Howard 1995
• Howard 1996
• Howard 2005
• Hriadel et al 2026
• Hu and Huang 2017
• Hu et al 2021
• Hu et al 2022
• Hu et al 2022
• Hu et al 2022
• Hu et al 2023
• Hu et al 2024
• Hu et al 2025
• Hu et al 2026
• Huang 2025
• Huang et al 2017
• Huang et al 2018
• Huang et al 2019
• Huang et al 2024
• Hubble and Smith 1979
• Huben and Metsker 1978
• Hughes 1995
• Huh and Shim 2010
• Huhn et al 2009
• Human Factors in Unmanned 2016
• Humphreys et al 2015
• Humphreys et al 2016
• Humphreys et al 2017
• Hunt and Azmy 1992
• Huo et al 2025
• Hutchinson 1932
• Huxley-Reynard 2001
• Hwang and Han 2025
• Hwang and Lee 2023
• Hwang et al 2022
• Hydraulic System Survivability
• Hydraulic System Survivability for
• Ibraheem 2019
• Ibrahim 2002
• Ilić et al 2016
• In et al 2007
• In-flight demo of multiple 2007
• Initial Unmanned Aircraft Sizing 2014
• Initial Unmanned-Aircraft Sizing 2012
• International Standard Atmosphere 2010
• Introduction to the Aircraft 1985
• Introduction to the Aircraft 2003
• Introduction to Unmanned Aircraft 2010
• Iqbal et al 2026
• Irfan bin Edi et al 2022
• Ironhill et al 2013
• Isac and Gosselin 2008
• Isci and Koyuncu 2022
• Ishak et al 2025
• Isnard et al 2023
• Ito et al 2020
• Ivancevic et al 2018
• Ivanets et al 2025
• Iyer et al 2025
• İşci and Günel 2021
• Jafari and Xu 2018
• Jafari et al 2017
• Jagtap 2025
• Jain et al 2017
• Jaiswal 1997
• Jaiswal 1997
• Jaiswal and Nagabhushana 1994
• Jaiswal and Nagabhushana 1995
• James 1988
• James and Stein 1978
• Jameson 2009
• Janda et al 2013
• Jann 2026
• Jastrzębski et al 2018
• Jayanthi et al 2022
• Jeffcoat 2003
• Jenkins et al 2005
• Jenks 2026
• Jensen 2016
• Jensen 2021
• Jeong 2026
• Jeong and Oh 2026
• Jeong et al 2026
• Jerie 1975
• Ji et al 2019
• Ji et al 2024
• Ji et al 2024
• Jia et al 2016
• Jia et al 2023
• Jian et al 2024
• Jiandong et al 2021
• Jiang et al 2026
• Jianhong and Gongqian 2025
• Jianhong and Yanxiang 2026
• Jiapan and Yongshan 2021
• Jin et al 2022
• Jin et al 2023
• Jin et al 2024
• Jing et al 2017
• Jizhu Liu et al 2009
• Jo et al 2014
• Jo et al 2015
• Johns et al 2001
• Johnson 1969
• Johnson 1986
• Johnson 1989
• Johnson 1990
• Johnson and Hixson 2008
• Johnson and O’Neill 2003
• Johnson et al 1991
• Johnson et al 2005
• Jones 2018
• Jones and Dye 2016
• Jones et al 2006
• Jones et al 2021
• Jorris et al 2011
• Jossie 2007
• Joyce 2026
• Jun 2024
• Jun and D’Andrea 2003
• Jung et al 2014
• Jung et al 2015
• Jung et al 2024
• Jung et al 2025
• Junlei et al 2017
• Jóźko and Włodarczyk 2020
• Kahn and Edwards 2015
• Kaifang Wan and Gao 2011
• Kaimakamis and Zographopoulos 2012
• Kallstrom and Heintz 2020
• Kan
• Kandis and Witkowski 2019
• Kang and Ryu 2021
• Kang et al 2023
• Kang et al 2023
• Kangaspunta and Salo 2013
• Kannan et al 2014
• Karabetsky 2018
• Karacan et al 2019
• Karimoddini et al 2022
• Karmeshu and Jaiswal 1986
• Karr 1974
• Karr 1975
• Karr 1976
• Karr 1976
• Karr 1977
• Karr 1977
• Kaushik 2018
• Kaya et al 2018
• Kaya et al 2019
• Kaymal 2016
• Ke et al 2015
• Keane 2011
• Keles et al 2025
• Keleş 2022
• Keller 1982
• Kelner and Ziółkowski 2020
• Kennedy and Lowry 1995
• Kennett et al 2014
• Keshmiri et al 2018
• Kessler et al 2000
• Khalatov et al 2023
• Khalid 2016
• Khalid 2017
• Khan 2021
• Khan et al 2022
• Kharchenko et al 2017
• Khatiwada et al 2018
• Khobin and Goncharenko 2021
• Khreish et al 2005
• Khurramov and Bobomurodov 2021
• Kiam et al 2022
• Kidder 1957
• Kihlman et al 2004
• Kilgore et al 2009
• Kim 2026
• Kim and Bang 2016
• Kim and Kim 2026
• Kim and Lee 2011
• Kim and Lee 2018
• Kim and Lee 2022
• Kim and Morrison 2018
• Kim and Morrison 2019
• Kim et al 2001
• Kim et al 2015
• Kim et al 2015
• Kim et al 2017
• Kim et al 2017
• Kim et al 2019
• Kim et al 2026
• Kimbleton 1971
• King
• Kirk et al 2022
• Kladis et al 2011
• Klein 2002
• Klenke and Ortiz 2011
• Klesh et al 2009
• Klimowitch 1978
• Klipp et al 2021
• Knacke 1985
• Knapik et al 2011
• Kocaman 2026
• Kohn 2022
• Kong et al 2020
• Kong et al 2020
• Kong et al 2020
• Kong et al 2022
• Kong et al 2023
• Koo 2012
• Korecki and Hoika 2026
• Kostelezky 2005
• Kostelezky and Schmitt 1999
• Koster et al 2011
• Koyuncu and Bostanci 2009
• Kozlov 2013
• Kozlov 2013
• Krause et al 2024
• Kress and Talmor 1999
• Kress et al 2018
• Krings et al 2013
• Krishnamoorthy
• Krupnik 2022
• Kucherov et al 2019
• Kuhn et al 1981
• Kuhn et al 2026
• Kula 2009
• Kumar 1997
• Kumar 2020
• Kumar et al 2026
• Kumaravelu et al 2022
• Kumari and Raghunath 2016
• Kurdyla 1963
• Kurkcu et al 2011
• Kurnaz et al
• Kurniawan et al 2019
• Kurzke and Halliwell 2018
• Kurzke et al 2025
• Kutney 1964
• Kuwamura and Hara 2017
• Kuznetsov and Shpakovsky 2020
• Künzel et al 2025
• Laitone 1978
• Lalitha et al 2023
• Lanchester 1955
• Lanchester, Frederick William 1868-1946 2017
• Langen et al 2023
• Lanteigne and O’Reilly 2020
• Laracy and Marlowe 2019
• Larm 2004
• Larson 1958
• Laubendorfer et al 1965
• Layfield and Carpenter 1995
• Learning Curves Production Breaks/Lost 2015
• Learning Curves Production Breaks/Lost 2026
• Ledyankina et al 2018
• Lee and Jeong 2025
• Lee and Kang 2025
• Lee and Kim 2020
• Lee and Na 2023
• Lee and Park 2024
• Lee and Tahk 2019
• Lee and Yee 2024
• Lee et al 2008
• Lee et al 2008
• Lee et al 2008
• Lee et al 2008
• Lee et al 2017
• Lee et al 2018
• Lee et al 2025
• Lee et al 2025
• Lei 2014
• Lempert 1975
• Leonard et al 2012
• Leonard et al 2013
• Lepingwell 1987
• Lepingwell 1990
• Levin and Shpund 1995
• Levulis et al 2018
• Lewis 2002
• Lewkowicz 2026
• Leylek and Costello 2010
• Li and Chen 2019
• Li and Li 2010
• Li and Liu 2012
• Li and Rodrigues 2025
• Li and Tiniakov 2026
• Li and Tiniakov 2026
• Li and Tiniakov 2026
• Li and Tiniakov 2026
• Li and Tiniakov 2026
• Li et al 2019
• Li et al 2020
• Li et al 2022
• Li et al 2022
• Li et al 2022
• Li et al 2022
• Li et al 2022
• Li et al 2022
• Li et al 2023
• Li et al 2024
• Li et al 2024
• Li et al 2024
• Li et al 2024
• Li et al 2025
• Li et al 2025
• Li et al 2025
• Li et al 2025
• Li et al 2025
• Li et al 2025
• Li et al 2026
• Liang 2008
• Liang 2010
• Liang et al 2014
• Liang et al 2022
• Liang et al 2024
• Lieret et al 2022
• Liersch and Bishop 2018
• Liersch and Huber 2014
• Life Cycle Cost 2010
• Lilley et al 1991
• Lima Filho et al 2021
• Lin 2002
• Lin et al 2011
• Lin et al 2023
• Lin et al 2024
• Lindsay and Sun 2020
• Lingard et al 2013
• Linne 2022
• Liu 2004
• Liu 2022
• Liu and Ma 2017
• Liu et al 2007
• Liu et al 2019
• Liu et al 2020
• Liu et al 2020
• Liu et al 2021
• Liu et al 2022
• Liu et al 2022
• Liu et al 2023
• Liu et al 2023
• Liu et al 2023
• Liu et al 2023
• Liu et al 2024
• Liu et al 2024
• Liu et al 2024
• Liu et al 2024
• Liu et al 2024
• Liu et al 2024
• Liu et al 2025
• Liu et al 2026
• Liu et al 2026
• Liu et al 2026
• Liu Zhi and Wang Yong 2012
• Lizzio et al 2021
• Lloyd et al 1978
• Lockwood 1964
• Lofthouse and Cotton 2017
• Logistics Management Inst Bethesda Md 1965
• Logistics Management Inst Bethesda Md 1967
• Lohrmann 2001
• Lokhande 2026
• Long 1994
• Longino 1994
• Love and Argrow 2021
• Lovelace 1998
• Low Cost Cargo Aircraft 1960
• Lowry et al 1978
• Lu et al 2011
• Lu et al 2015
• Lu et al 2019
• Luca et al 2024
• Lucas and Dinges 2004
• Lucas and Turkes 2003
• Luckring and Boelens 2015
• Ludington et al
• Lunsford and Bradley 2025
• Luo 2025
• Luo et al 2019
• Luo et al 2025
• Lyalin and Morozov 2005
• Lynn and Gursul 2006
• Lyons et al 2021
• Lyshevski 2018
• Ma
• Ma et al 2020
• Ma et al 2021
• Ma et al 2024
• Machin et al 2001
• Machin et al 2011
• Machin et al 2011
• Macho-Stadler 2024
• MacKay
• Madanayaka et al 2026
• Magnetic Coupler Design for 2025
• Mahmoud and Mohamed 2014
• Maier et al 2024
• Majd and Pindyck 1987
• Maldonado et al 2017
• Malhotra et al 2024
• Malik 2024
• Malyar and Shcheholskyi 2026
• Mammadov and Gueaieb 2014
• Mangel 1979
• Mangulis 1980
• Manley 2018
• Mann 1976
• Mann 1978
• Manning et al 2004
• Manoharan et al 2023
• Manoilo 2025
• Mansfield 1973
• Manufacturing cost estimation A 1993
• Maria-Agneta and Stef 2011
• Marques 2013
• Marques 2014
• Martin and Esteban 2025
• Marx et al 1995
• Masters 1986
• Matlock et al 2009
• Matsuno and Andreeva-Mori 2023
• Matsushima 2001
• Mauch et al 1980
• Maughan et al 2015
• Max Chung and Tuan 2020
• Mazzola and McCardle 1997
• McClure 1977
• McGee and Hedrick 2006
• McGuire 1986
• McKinnis et al 2021
• McLaughlin
• McMenamin and McMenamin 1997
• McMenamin and Pochettino 1984
• Mechatronic Design of Unmanned 2015
• Mehaffie 1979
• Mehalic and Ziemianski 1980
• Mei et al 2024
• Mekdeci and Cummings 2009
• Menq et al 2007
• Menting et al 2020
• Merheb
• Merrill 1976
• Merz et al 1970
• Metasurface-Driven Electronic Attack 2024
• Meyer and Schulte 2020
• Meyer and Schulte 2022
• Meyer et al 2007
• Michelson and Domercant 2019
• Miesikowska 2017
• Mihalik and Keane 2022
• Miller 1993
• Miller 2006
• Miller 2024
• Milne and Arthur 2006
• Minglang et al 2018
• Minzner et al 1976
• Mirchandani 2020
• Mishra et al 2022
• Mishra et al 2023
• Mittal 2023
• Mittal and Gillespie 2026
• Mkrtchyan and Johari 2011
• Mobile Autonomous Recovery Landing 2024
• Montazeri-Gh and Yousefi Dastjerdi 2024
• Moog and Kross 1982
• Moog et al 1979
• Moog et al 1979
• Morimoto et al 2015
• Morris and Olson 2011
• Morris et al 2005
• Moser 2011
• Moses 1990
• Moses 1991
• Moses 1991
• Moses 1992
• Moses 1995
• Most 2016
• Most and Feasey 2021
• Most and Stroup 2021
• Mosyam and Ardian 2026
• Motter and High 2009
• Moudgil et al 2026
• Moving beyond attrition in 2023
• Mu et al 2026
• Mueller 2018
• Mukherjee
• Mukherjee 2021
• Multi-Disciplinary Cyber-Physical Optimization for 2012
• Multi-Rotors A Revolution In 2015
• Munro and Krus 2002
• Mushynski and Johnson 2017
• Muslu et al 2026
• Mustopa 2022
• Nadler 2015
• Nagy and Laufer 2024
• Nangia and Palmer 2006
• Nangia and Palmer 2011
• Nangia et al 2018
• Nangia et al 2019
• Narayanan 2002
• Naundrup
• Navickiene et al 2025
• Nelson and Dix 2003
• Nelson et al 2006
• Nemet 2006
• Neto et al 2024
• Neubauer et al 2022
• Neubauer et al 2023
• Neubauer et al 2023
• Neuenswander 2013
• Neufeld 2021
• Neufeld and Chung 2005
• Neustadt et al 1967
• Nguyen et al 2024
• Nguyen et al 2024
• Nguyen et al 2025
• Nichols 1998
• Nichols 2021
• Nikbay et al 2025
• Noh and Choi 2012
• Noise measurements for UAS
• Nugent and Girard 2003
• Nussbaum 1994
• O’Farrell et al 2016
• O’Reilly 1999
• O’Rourke et al 1999
• Oh et al 2019
• Ojha 1992
• Okcu 2016
• Ol 2006
• Olcer 2015
• Oliver 2012
• Oncu and Yildiz 2014
• Operating an Unmanned Aerial 2018
• Opromolla 2020
• Optimization of Cruising Flights 1995
• Ordaz et al 2004
• Orhan et al 2026
• Oruc and Baklacioglu 2024
• Osterbeck et al 1979
• Otto and Thomas W. 1975
• Overview of Unmanned Aircraft 2012
• Overview of Unmanned Aircraft 2014
• Owens et al 2006
• Ozyetis and Alemdaroglu 2014
• Pabon Arias
• Pack and York 2008
• Pack et al
• Pagan et al 2018
• Palaia 2026
• Palazzo and Rosenfeld 1983
• Palmore 1996
• Pan et al 2020
• Pan et al 2022
• Panigrahi and Tripathy 2025
• Papageorgiou 2022
• Papandreas and Jacox 1994
• Parametric Flyaway Cost Estimating 2024
• Park and Geng 2023
• Park and Kim 2026
• Park and Ro 2004
• Park et al 2016
• Park et al 2017
• Park et al 2022
• Parker 1986
• Parry and Schoenstadt 1990
• Patel et al 2018
• Paterson 1999
• Paterson and Paterson 1997
• Path Planning for Multiple 2010
• Pathak 1975
• Patterson 1989
• Paul and Paul 2023
• Paul et al 2025
• Pauls 2012
• Payton 2011
• Paz et al 2026
• Pearson 1972
• Pei 2019
• Pei et al 2014
• Pei et al 2019
• Peng et al 2022
• Peng Teng et al 2008
• Pennsylvania State Univ University Park 2001
• Pepermans et al 2018
• Pepper 1977
• Pepper and Collins 1981
• Pepper and Collins 1982
• Pericon 2024
• Perry 2000
• Perry 2003
• Peterson 1967
• Peterson and Staley 2011
• Peterson et al 1986
• Peterson et al 2024
• Petrock and Huizenga 2006
• Petterson 2006
• Petterson 2006
• Pettigrew 1983
• Pettit et al 2003
• Pham
• Pham and Sim 2002
• Phase 2 program on 1975
• Phillips et al 2019
• Pi et al 2023
• Pierron and Lahire
• Pilyugin and Khlebnikov 2010
• Pinon et al 2022
• Placco et al 2025
• Plaza del Pino et al 2024
• Podhradsky et al 2013
• Podhradsky et al 2013
• Pohya et al 2018
• Pokorny 2026
• Pomranky 2006
• Pope et al 2021
• Pope et al 2023
• Pourgol-Mohammad and Khayati 2021
• Powell 2001
• Practice for Design and
• Practice for Design and
• Practice for Design and
• Prasad 2025
• Prasad and Unnikrishnan 2006
• Prasetiyo et al 2024
• Preparation of turbojet engine 2002
• Pressures and Temperatures for 2000
• Priest 1995
• Primatesta et al 2021
• Prior 2018
• Prkačin et al 2024
• Product Life Cycle Cost
• Properties of the U.S 2014
• Properties of the U.S 2024
• Protopopescu et al 1990
• Protsenko et al 2019
• Pulley 1977
• Pyzynski 2020
• Qi and Xie 2026
• Qian et al 2025
• Quan et al 2025
• Queen 1976
• Queen et al 1977
• Radmanesh et al 2018
• Radovanović et al 2023
• Ragi and Chong 2013
• Rahman et al 2026
• Raja 2011
• Ramasamy 2015
• Ramasamy et al 2015
• Ramírez López and Żbikowski 2018
• Randle et al 2011
• Rasmussen and Schumacher 2007
• Rasmussen et al 2006
• Ravishankar and Chakravarthy 2018
• Rebikoff
• Reconstructing Lanchester Warfare Models 2021
• Reghunath and Ramaiah 2022
• Reichenbach 2003
• Reichstein et al 2022
• Reid et al 2004
• Reinhard et al 1997
• Ren et al 2023
• Renau and Tavis 1972
• Renehan 1997
• Retana and Rodriguez-Cortes 2007
• Review of ONR’s Uninhabited 2000
• Richardson and Tommasini 1967
• Rickman et al 1976
• Ridder and HandUber 2005
• Ridgard 2008
• Rithirun and Sooraksa 2013
• Roberts and Ferrazano 2004
• Robillard and Blore 1964
• Rocket-Assisted Take-Off for the 1965
• Rogalski 2018
• Rohlf et al 2012
• Roltgen and Gilbert 2010
• Ronchieri and Innocenti 2007
• Roncolini and Quaranta 2024
• Rorsted 1999
• Rosaldo-Serrano et al 2017
• Rosales and Gross 2017
• Roseberg 1982
• Rosenblum et al 2022
• Rosenfeld and Davis 1986
• Ross et al 2019
• Rotaru et al 2016
• Roth and Schulte 2020
• Roth and Schulte 2022
• Roth and Schulte 2022
• Roth et al 2020
• Roussos et al 2025
• Rowe et al 2014
• Ru and Subbarao 2017
• Ru et al 2026
• Ruck and Krichbaum 1968
• Rudnitski
• Ruetten 2018
• Ruetten et al 2014
• Ruf and Stütz 2016
• Ruf and Stütz 2018
• Ruff and Calhoun 2013
• Runkle and Drobnik 1979
• Runkle and Wolf 1995
• Rusu 1988
• Rutkay and Laliberté 2016
• Sabatini R 2013
• Sadraey 2010
• Sadraey 2018
• Sadraey 2025
• Safe Coordinated Maneuvering of 2016
• Sagduyu et al 2018
• Sager 2009
• Sahu et al 1997
• Saied
• Saif et al 2014
• Sakarya et al 2018
• Salguero and Rhudy 2017
• Salhi et al 2026
• Salim Al-khalidi and Hamid 2001
• Samiei and Sun 2020
• Sanders 1965
• Sands 2009
• Santis
• Santis 1973
• Sarabakha
• Saraswat and Pant 2025
• Sastry 2001
• Sathe and Pant 2010
• Schacht-Rodriguez et al 2019
• Schaffner et al 2013
• Schatzle and Curry 1979
• Schatzle and Curry 1980
• Scheidt 2014
• Schiller and Zawodny 2018
• Schilling 1978
• Schmitt and Schulte 2015
• Schmitt and Schulte 2015
• Schober and Franklin 1968
• Schoendorf 1972
• Schold and Mittal 2024
• Scholz 2021
• Schopferer and Pfeifer 2015
• Schosser et al 2026
• Schuette et al 2014
• Schultz et al 1964
• Schwartz 1988
• Schwerd and Schulte 2021
• Schütte et al 2012
• Scott 2021
• Sease et al 2023
• Selection of Bypass Ratio 2003
• Selection of Fan Pressure 2015
• Selig 2010
• Selmonaj et al 2023
• Selmonaj et al 2025
• Selmonaj et al 2026
• Semke 2016
• Semke 2021
• Sendner et al 2018
• Sengupta et al 2009
• Sevcik and Oh
• Sforza 2020
• Shahbazi 2025
• Shakir 1996
• Shang et al 2025
• Shanshan et al 2020
• Shao et al 2013
• Sharif 2022
• Sharma and Pack 2013
• Sharma et al 2012
• Sharpe et al 2021
• Shen and Liu 2025
• Shen et al 2025
• Sheng et al 2023
• Sherer et al 2008
• Sherstjuk 2015
• Sherstjuk et al 2019
• Shi et al 2018
• Shi et al 2022
• Shim et al 2008
• Shima et al 2014
• Shimpi and Sawarkar 2026
• Shirkey 2009
• Shively et al 2011
• Shivers and Smith 1974
• Shivers and Smith 1975
• Shiyou et al 2011
• Shkarayev 2009
• Shmelova et al 2025
• Shook et al 2009
• Shumway and Beard 2025
• Shyu and Hsiao 2014
• Sijabat and Indriyanto 2021
• Silbert et al 1986
• Simmons et al 2023
• Simms 2023
• Simpson et al 2003
• Sims
• Sims and Biezad 2010
• Sineglazov and Daskal 2017
• Singh and Kamal 2025
• Singh and Singh 1991
• Siotia et al 2026
• Skillen and Crossley 2005
• Slade et al 2006
• Slapnicar
• Sleator 1964
• Smith
• Smith 2003
• Smith and Schnell 2026
• Smith and Starks 2011
• Smith and Williams 1993
• Smith et al 1964
• Smith et al 1978
• Smith et al 2007
• Smunt 1999
• Smunt 2000
• Smunt 2011
• Snyder 2000
• Sobers et al 2010
• Soldatov et al 2025
• Song 2008
• Song et al 2026
• Sosa 1997
• Souli et al 2025
• Soykan and Koksalmis 2026
• Space environment natural and
• Spaight and Selfors 1967
• Sparrow and Henschke 2023
• Specification for Aircraft Emergency
• Specification for Design and
• Speight 1995
• Sperling et al 2008
• Ss and Mathiyazaghan 2016
• Staack et al 2021
• Stachura and Frew 2011
• Stadmore 1979
• Standard Atmosphere 2005
• Standard Atmosphere 2023
• Standard Atmosphere 2024
• Standard atmosphere chart 1927
• Standard atmosphere chart supersedes 1927
• Standard Specification for Aircraft
• Steele and Barnum 1966
• Steenrod and Musch 1981
• Stegall 2001
• Stein et al 2003
• Sterk et al 2016
• Stewart 2013
• Stewart et al 2012
• Stoneking et al 2006
• Stradtner et al 2020
• Strenzke et al 2011
• Subbarao and Ru 2017
• Subramaniam et al 2012
• Sudhakar et al 2025
• Suh 1990
• Suit et al 1964
• Suminsby 2002
• Sun and Pack 2016
• Sun et al 2022
• Sun et al 2024
• Sun et al 2026
• Sun et al 2026
• Sunil
• Support Jamming Electronic Attack
• Surka 2001
• Survivability of Unmanned Autonomous 2016
• Survivability PS and PK 1985
• Survivability PS and PK 2003
• Sushchenko and Goncharenko 2016
• Svoboda 1999
• Swearingen et al 2015
• System dynamics applications for 2021
• Szabolcsi 2018
• Szabolcsi 2018
• Szabolcsi 2018
• Szafranski et al 2014
• Szczepaniak et al 2019
• Tachinina et al 2017
• Taflove and Umashankar 1989
• Taha and Hajj 2013
• Takita and Kashitani 2016
• Talay and Poole 1971
• Tam 1998
• Tan et al 2012
• Tan et al 2018
• Tan et al 2022
• Tan et al 2024
• Tan et al 2024
• Tang
• Tang and Li 2012
• Tang et al 2026
• Tanveer and Ahmad 2023
• Tao et al 2024
• Taranto and Abdulrahim 2023
• Tate and Gillard 1975
• Tavis 1973
• Taylor 1971
• Taylor 1972
• Taylor 1973
• Taylor 1974
• Taylor 1974
• Taylor 1979
• Taylor 1979
• Taylor 1979
• Taylor 1979
• Taylor 1980
• Taylor 1980
• Taylor 1981
• Taylor 1982
• Taylor 1982
• Taylor 1983
• Taylor 1983
• Taylor 1984
• Taylor and Brown 1976
• Taylor and Brown 1978
• Taylor and Comstock 1977
• Taylor et al 2021
• Taşbaş et al 2023
• Teague et al 2008
• Tekin et al 2026
• Tekinalp and Ariyibi 2015
• Terwilliger and Ison 2014
• Teufel et al 2003
• The Control of Multiple 2026
• The Flight Environment Standard 2021
• The Future of Unmanned 2016
• The International Standard Atmosphere 2017
• The international standard atmosphere 2026
• The origins of unmanned 2017
• The People’s Liberation Army’s 2025
• The Standard Atmosphere 1964
• The Standard Atmosphere 1976
• Thokala et al 2012
• Thomas and Thomas 2008
• Thome 2003
• Thompson and Robertson 1990
• Throndson 1981
• Throndson 1982
• Thrust-to-Weight Ratio and Wing 2024
• Tiaden and Yakimenko 2008
• Tiaden and Yakimenko 2009
• Tierney et al 2005
• Tierney et al 2021
• Tilley et al
• Timis and Dulf 2024
• Timmers et al 2009
• Tinoco
• Tirkel 2013
• Tiwari
• To
• Tomac et al 2012
• Tomczyk and Rogalski 2005
• Toni 1970
• Torres et al 2017
• Toussaint et al 2007
• Towhidnejad and Clifford 2009
• Tran
• Trang and Usami 2017
• Trigg 1973
• Trotsyuk and Lesohorskyi 2026
• Tsai et al
• Tsourdos et al 2010
• Tsuchiya 1990
• Tsuchiya 2004
• Tupitsin and Stepanenko 2020
• Turner Camacho and Danforth 2026
• Turning Flights of Turbojet 1995
• Turns and Kraige
• Tutt et al 2009
• Tutt et al 2009
• Tutt et al 2022
• Tuzcu 2007
• Tvaryanas 2006
• Tvaryanas 2006
• Tvaryanas and Maupin 2013
• Tvaryanas et al 2012
• Tweddale et al 2011
• Twesme and Corzine 2003
• Tzes et al 2023
• UAV Control 2016
• UAV System Deployment 2010
• UAV Systems Continuing Evolution 2010
• Underwood et al 2022
• Unified Cruise Performance 2013
• Unmanned Aerial Vehicle Collaboration 2026
• Unmanned Aerial Vehicle Design 2024
• Unmanned Aerial Vehicle Dynamics 2016
• Unmanned Aerial Vehicle Path 2014
• Unmanned Aerial Vehicle UAV 2022
• Unmanned Aerial Vehicles 2013
• Unmanned Aerial Vehicles 2020
• Unmanned Aerial Vehicles for 2016
• Unmanned Aerial Vehicles UAVs 2015
• Unmanned Air System Search 2012
• Unmanned Air Vehicles 2017
• Unmanned Aircraft Categories 2012
• Unmanned Aircraft Categories 2014
• Unmanned Aircraft Geometry and 2014
• Unmanned Aircraft System Elements 2016
• Unmanned Aircraft System Operations 2016
• Unmanned Aircraft Vehicles 2013
• Unmanned Autonomous Vehicle 2016
• Unmanned-Aircraft Geometry and Configurations 2012
• Unnikrishnan and Prasad 2004
• Ure and Inalhan 2009
• US Standard Atmosphere Model 2014
• Usach Molina
• Using the Learning Curve 2010
• Uybarreta et al 2025
• Vajda and Maris 2021
• Valavanis and Kontitsis
• Valianti et al 2023
• Vallespin et al 2011
• Van Dyke et al 1990
• van Es 2002
• van Rooij and Cummings 2018
• van Rooij et al 2019
• Vanualailai et al 2013
• Varela 2014
• Vashishth et al 2024
• Vaughan 2003
• Velasco Carrau
• Venugopalan et al 2012
• Vepa 2016
• Vepa 2023
• Vepa 2026
• Vepa 2026
• Vergnolle 1995
• Vice 1986
• Vice 1987
• Vicroy et al 2012
• Vicroy et al 2014
• Vicroy et al 2014
• Video Communications in Unmanned 2013
• Villarreal-Valderrama et al 2020
• Villette et al 2026
• Voigt et al 2019
• Volovoda 2024
• Vos 2019
• Voss and Klimmek 2016
• Voss and Klimmek 2016
• Voss et al 2011
• Vu 2023
• Vu et al 2021
• Wachlin et al 2022
• Wade 2021
• Waggener 1987
• Wagner et al 1990
• Wailes 1989
• Wallis et al
• Walters et al 2002
• Wang
• Wang and Wang 2024
• Wang and Zhou 2022
• Wang et al 2010
• Wang et al 2013
• Wang et al 2016
• Wang et al 2016
• Wang et al 2018
• Wang et al 2020
• Wang et al 2021
• Wang et al 2021
• Wang et al 2022
• Wang et al 2022
• wang et al 2022
• Wang et al 2023
• Wang et al 2023
• Wang et al 2023
• Wang et al 2023
• Wang et al 2024
• Wang et al 2024
• Wang et al 2024
• Wang et al 2024
• Wang et al 2024
• Wang et al 2024
• Wang et al 2025
• Wang et al 2026
• Wang Yun-sheng et al 2016
• Ward and Neeley 1959
• Washburn 2000
• Washburn and Kress 2009
• Washburn and Kress 2009
• Watkins 1986
• Watkins et al 2017
• Watson and Gonzalez 2023
• Watson Jr. 2003
• Waye et al 1986
• Waye et al 1995
• Webb 2022
• Weeks 2000
• Wei and Pearson 1974
• Wei et al 2015
• Wei et al 2021
• Weimer 1977
• Weinberg 2025
• Weiskopf et al 2002
• Weiss 1966
• Weiss 1968
• Welch 2007
• Westat Inc Rockville Md 2001
• Whalley 1973
• White 2017
• White 2017
• White and Strykowski
• Whitmore and Hennings 2007
• Whitmore et al 2004
• Wickens and Dixon 2002
• Wiersgalla 2011
• Wigley and Jasiunas
• Wijaya 2025
• Williams 2006
• Wills 2015
• Wills 2015
• Wilt et al 2022
• Wiper et al 2000
• Wireless Communications and Networking 2020
• Wise 2003
• Wise 2004
• Witkowski 1999
• Witkowski 1999
• Witkowski et al 2022
• Wolf 1991
• Wolf and Fallon 2011
• Wolfe and Ruda 1979
• Wong et al 2015
• Woolvin 2006
• Worch et al 1996
• Worth 1965
• Worth 1966
• Wrage 2011
• Wright 1975
• Wright et al 2022
• Wright et al 2024
• Wroblewski and Ansell 2020
• Wu and Han 2019
• Wu and Litt 2023
• Wu et al 2019
• Wu et al 2019
• Wu et al 2019
• Wu et al 2020
• Wu et al 2022
• Wu et al 2025
• Wu et al 2025
• Wu et al 2026
• Wuwer et al 2025
• Wyatt 2003
• Wyllie 2001
• Wyllie et al 1997
• Xi and Liu 2020
• Xia et al 2023
• Xiang and Zhou 2025
• Xiang et al 2023
• Xiao and Jiancheng 2005
• Xie et al 2015
• Xu 2009
• Xu and Carrillo 2015
• Xu and Chen 2021
• Xu and Zhou 2025
• Xu et al 2012
• Xu et al 2019
• Xu et al 2022
• Xu et al 2023
• Xu et al 2024
• Xu et al 2024
• Xu et al 2025
• Xuan et al 2022
• Xue et al 2015
• Xue et al 2019
• Xue et al 2019
• Yakimenko et al 2008
• Yan 2025
• Yan et al 2025
• Yang 2017
• Yang 2024
• Yang and Yee 2022
• Yang et al 2014
• Yang et al 2019
• Yang et al 2019
• Yang et al 2020
• Yang et al 2024
• Yang et al 2024
• Yang et al 2025
• Yang et al 2025
• Yang et al 2025
• Yang et al 2025
• Yao et al 2018
• Yao et al 2021
• Yao et al 2024
• Yeakle et al 2009
• Yi et al 2019
• Yin and Wen 2012
• Yin et al 2020
• Yin et al 2021
• Yoo et al 2021
• Yoo et al 2021
• Yoo et al 2022
• Yoon and Kim 2010
• Yoon and Kim 2017
• Yoon et al 2009
• Yoon et al 2026
• Young 2010
• Young et al 2014
• Young et al 2022
• Yu et al 2023
• Yu et al 2023
• Yu et al 2023
• Yu et al 2024
• Yu et al 2024
• Yu et al 2025
• Yuan and Fang 2024
• Yuan et al 2023
• Yuan et al 2025
• Yucer 2026
• Yucer and Nacakli 2023
• Yuma Proving Ground Az 2013
• Yuma Test Center Yuma Proving Ground Az 2008
• Yunhui et al 2024
• Yıldırım Dalkıran and Kırteke 2024
• Zafirov 2010
• Zakaria 2013
• Zakharin and Ponomarenko 2017
• Zarei and Maadi 2026
• Zawodny et al 2018
• Zbrutsky et al 2024
• Zhang
• Zhang 2023
• Zhang and Bradley 2022
• Zhang and Qin 2026
• Zhang et al 2011
• Zhang et al 2016
• Zhang et al 2019
• Zhang et al 2020
• Zhang et al 2020
• Zhang et al 2020
• Zhang et al 2021
• Zhang et al 2022
• Zhang et al 2022
• Zhang et al 2022
• Zhang et al 2023
• Zhang et al 2023
• Zhang et al 2023
• Zhang et al 2024
• Zhang et al 2024
• Zhang et al 2024
• Zhang et al 2024
• Zhang et al 2024
• Zhang et al 2025
• Zhang et al 2025
• Zhang et al 2025
• Zhang et al 2025
• Zhang et al 2026
• Zhang et al 2026
• Zhang et al 2026
• Zhang et al 2026
• Zhang et al 2026
• Zhao 2003
• Zhao and Huang 2018
• Zhao and Li 2021
• Zhao and Zhu 2016
• Zhao et al 2026
• Zheng and Duan 2023
• Zheng et al 2019
• Zheng et al 2024
• Zheng et al 2025
• Zheng et al 2026
• Zheng et al 2026
• Zhong et al 2026
• Zhou and Huang 2020
• Zhou et al 2014
• Zhou et al 2019
• Zhou et al 2020
• Zhou et al 2021
• Zhou et al 2022
• Zhou et al 2024
• Zhou et al 2024
• Zhou et al 2024
• Zhou et al 2024
• Zhou et al 2025
• Zhou et al 2026
• Zhu et al 2013
• Zhu et al 2018
• Zhu et al 2019
• Zhu et al 2024
• Zhurin 2019
• Ziemianski 1981
• Zimper and Huber 2019
• Zimper and Hummel 2014
• Zimper and Hummel 2018
• Zolanvari et al 2018
• Żugaj 2017