hypersonic flight

Hypersonic flight is flight through the atmosphere below altitudes of about at speeds greater than Mach 5, a speed where dissociation of air begins to become significant and high heat loads exist. Speeds over Mach 25 have been achieved below the thermosphere as of 2020.

Hypersonic vehicles are able to maneuver through the atmosphere in a non-parabolic trajectory, but their aerodynamic heat loads need to be managed.

History

The first manufactured object to achieve hypersonic flight was the two-stage Bumper rocket, consisting of a WAC Corporal second stage set on top of a V-2 first stage. In February 1949, at White Sands, the rocket reached a speed of , or about Mach 6.7. The vehicle, however, burned on atmospheric re-entry, and only charred remnants were found. In April 1961, Russian Major Yuri Gagarin became the first human to travel at hypersonic speed, during the world's first piloted orbital flight. Soon after, in May 1961, Alan Shepard became the first American and second person to fly hypersonic when his capsule reentered the atmosphere at a speed above Mach 5 at the end of his suborbital flight over the Atlantic Ocean.

In November 1961, Air Force Major Robert White flew the X-15 research aircraft at speeds over Mach 6.
On 3 October 1967, in California, an X-15 reached Mach 6.7.

The reentry problem of a space vehicle was extensively studied.Alfred J. Eggers, H. Julian Allen, Stanford Neice (10 December 1954)
"A comparative analysis of the performance of long-range hypervelocity vehicles"
NACA report 1382, pp. 1141–1160 The NASA X-43A flew on scramjet for 10 seconds, and then glided for 10 minutes on its last flight in 2004. The Boeing X-51 Waverider flew on scramjet for 210 seconds in 2013, finally reaching Mach 5.1 on its fourth flight test. The hypersonic regime has since become the subject of further study during the 21st century, and strategic competition between the United States, India, Russia, and China.In, for example Waverider hypersonic weapons delivery, China has flown a Mach 5.5 vehicle for 400 seconds, at 30 km altitude, demonstrating large-angle deviations from a ballistic trajectory, as well as recovery of the payload. See

3 August 2018 China tests hypersonic aircraft Starry Sky-2
--Xingkong-2 (Starry-sky-2) first flight
China successfully tests first hypersonic aircraft that can .. Youtube clip XingKong-2 hypersonic aircraft (Starry Sky-2)
John Hyten statement 05:03, 8 August 2018 (UTC)
(15 Jun 2018) Lockheed Martin Hypersonic Conventional Strike Weapon (HCSW) Missile for US Air Force

Chris Martin (17 Dec 2019) Lockheed awards $81.5M contract for hypersonic missile motor
to Rocketdyne for HCSW $81.5M, ARRW
NPR (23 October 2018) Nations Rush Ahead With Hypersonic Weapons Amid Arms Race Fear DOV S. ZAKHEIM, OPINION CONTRIBUTOR (08/26/19) Putin built a hypersonic arsenal, while the Pentagon sleptColin Clark (19 June 2019) Raytheon, Northrop Will ‘Soon’ Fly Hypersonic Cruise Missile
Paris Air Show, new additive-process materials to build the combustor of a scramjet; potential integration among members of an intercommunicating swarm of hypersonics systems
DRDO successfully flight tests hypersonic technology vehicle
(September 7, 2020) Express News Service, The Indian Express

Current test targets, such a
Zombie Pathfinder
are not hypersonic
Rand Corporation (28 September 2017) Hypersonic Missile Nonproliferation
estimates there is less than a decade to prevent Hypersonic Missile proliferation.

Physics

Stagnation point

The stagnation point of air flowing around a body is a point where its local velocity is zero. At this point the air flows around this location. A shock wave forms, which deflects the air from the stagnation point and insulates the flight body from the atmosphere. This can affect the lifting ability of a flight surface to counteract its drag and subsequent free fall.

In order to maneuver in the atmosphere at faster speeds than supersonic, the forms of propulsion can still be airbreathing systems, but a ramjet does not suffice for a system to attain Mach 5, as a ramjet slows down the airflow to subsonic. Some systems ( waveriders) use a first stage rocket to boost a body into the hypersonic regime. Other systems ( boost-glide vehicles) use scramjets after their initial boost, in which the speed of the air passing through the scramjet remains supersonic. Other systems (munitions) use a cannon for their initial boost.Jared Keller

High temperature effect

Hypersonic flow is a high energy flow.Anderson, John (2016). Introduction to Flight (Eighth ed.) McGraw-Hill Education The ratio of kinetic energy to the internal energy of the gas increases as the square of the Mach number. When this flow enters a boundary layer, there are high viscous effects due to the friction between air and the high-speed object. In this case, the high kinetic energy is converted in part to internal energy and gas energy is proportional to the internal energy. Therefore, hypersonic boundary layers are high temperature regions due to the viscous dissipation of the flow's kinetic energy. Another region of high temperature flow is the shock layer behind the strong bow shock wave. In the case of the shock layer, the flow's velocity decreases discontinuously as it passes through the shock wave. This results in a loss of kinetic energy and a gain of internal energy behind the shock wave. Due to high temperatures behind the shock wave, dissociation of molecules in the air becomes thermally active. For example, for air at T > , dissociation of diatomic oxygen into oxygen radicals is active: O₂ → 2OB. deB. Darwent, National Bureau of Standard
(Jan 1970) Table of Bond Dissociation Energies in Simple Molecules
BDE: bond dissociation enthalpyJim Clark (12 Feb 202
Physical and Theoretical Chemistry Textbook Maps/Supplemental Modules (Physical and Theoretical Chemistry)/Thermodynamics/Energies and_Potentials/Enthalpy/Bond Bond Enthalpies
/ref>Answered by ron, stack exchang
(29 May 2014) Will heating diatomic oxygen enough break the O=O bonds?
/ref> For T > , dissociation of diatomic nitrogen into N radicals is active: N₂ → 2N Consequently, in this temperature range, a plasma forms:Jan Tegle
(4 Oct 2019) Research at Hyper Speed: The Pentagon's Research Laboratories Are Working Flat Out to Develop Hypersonic Weapons Technology
operating at —molecular dissociation followed by recombination of oxygen and nitrogen radicals produces nitric oxide: N₂ + O₂ → 2NO, which then dissociates and recombines to form ions: N + O → NO⁺ + e⁻ Anthony Capacci
(28 Mar 2023) U.S. Hypersonic Missile Test Marred by In-Flight Data Loss
ARRW plagued by loss of telemetry data in the latest test

Low density flow

At standard sea-level condition for air, the mean free path of air molecules is about $\lambda = 68 \,\mathrm$. At an altitude of , where the air is thinner, the mean free path is $\lambda = 1 \, \mathrm = 0.305 \, \mathrm$. Because of this large free mean path aerodynamic concepts, equations, and results based on the assumption of a continuum begin to break down, therefore aerodynamics must be considered from kinetic theory. This regime of aerodynamics is called low-density flow.
For a given aerodynamic condition low-density effects depends on the value of a nondimensional parameter called the Knudsen number $\mathrm$, defined as $\mathrm=\frac$ where $l$ is the typical length scale of the object considered. The value of the Knudsen number based on nose radius, $\mathrm=\frac$, can be near one.

Hypersonic vehicles frequently fly at very high altitudes and therefore encounter low-density conditions. Hence, the design and analysis of hypersonic vehicles sometimes require consideration of low-density flow. New generations of hypersonic airplanes may spend a considerable portion of their mission at high altitudes, and for these vehicles, low-density effects will become more significant.

Thin shock layer

The flow field between the shock wave and the body surface is called the shock layer. As the Mach number M increases, the angle of the resulting shock wave decreases. This Mach angle is described by the equation $\mu = \sin^ (a/v)$ where a is the speed of the sound wave and v is the flow velocity. Since M=v/a, the equation becomes $\mu = \sin^ (1/M)$. Higher Mach numbers position the shock wave closer to the body surface, thus at hypersonic speeds, the shock wave lies extremely close to the body surface, resulting in a thin shock layer. At low Reynolds number, the boundary layer grows quite thick and merges with the shock wave, leading to a fully viscous shock layer.

Viscous interaction

The compressible flow boundary layer increases proportionately to the square of the Mach number, and inversely to the square root of the Reynolds number.

At hypersonic speeds, this effect becomes much more pronounced, due to the exponential reliance on the Mach number. Since the boundary layer becomes so large, it interacts more viscously with the surrounding flow. The overall effect of this interaction is to create a much higher skin friction than normal, causing greater surface heat flow. Additionally, the surface pressure spikes, which results in a much larger aerodynamic drag coefficient. This effect is extreme at the leading edge and decreases as a function of length along the surface.

Entropy layer

The entropy layer is a region of large velocity gradients caused by the strong curvature of the shock wave. The entropy layer begins at the nose of the aircraft and extends downstream close to the body surface. Downstream of the nose, the entropy layer interacts with the boundary layer which causes an increase in aerodynamic heating at the body surface. Although the shock wave at the nose at supersonic speeds is also curved, the entropy layer is only observed at hypersonic speeds because the magnitude of the curve is far greater at hypersonic speeds.

Propulsion

Controlled detonation

Researchers in China have used shock waves in a detonation chamber to compress ionized argon plasma waves moving at Mach 14. The waves are directed into magnetohydrodynamic (MHD) generators to create a current pulse that could be scaled up to gigawatt scale, given enough argon gas to feed into the MHD generators.Tim Newcom
(6 Feb 2023) China Built a Hypersonic Generator That Could Power Unimaginable Weapons
/ref>

Rotating detonation

A rotating detonation engine (RDE)MRO Business Toda
(9 Oct 2023) RTX to build Gambit engine for DARPA
PRnewswir
(4 Oct 2023) RTX to develop rotating detonation engine for DARPA
/ref> might propel airframes in hypersonic flight; on 14 December 2023 engineers at GE Aerospace demonstrated their test rig, which is to combine an RDE with a ramjet/scramjet, in order to evaluate the regimes of rotating detonation combustion. The goal is to achieve sustainable turbine-based combined cycle (TBCC) propulsion systems, at speeds between Mach 1 and Mach 5.Joseph Trevithi
(14 Dec 2023) GE's Breakthrough In 'Detonating' Hypersonic Propulsion Is A Big Deal
GE Aerospac
(14 Dec 2023) GE Aerospace Demonstrates Hypersonic Dual-Mode Ramjet with Rotating Detonation Combustion
/ref>Eric Berge
(27 Mar 2024) The company building a rotating detonation engine is pushing the tech forward
Venus Aerospace: Mach 0.9 at 12,000 feetPeter Ray Alliso
Superfast drone fitted with new 'rotating detonation rocket engine' approaches the speed of sound
/ref>

Hybrid

Companies such as Hermeus, Venus Aerospace, and AstroMechanica are developing hybrid engines capable of operating from subsonic to hypersonic speeds.

Applications

Shipping

Transport consumes energy for three purposes: overcoming gravity, overcoming air/water friction, and achieving terminal velocity. The reduced trip times and higher flight altitudes reduce the first two, while increasing the third. Proponents claim that the net energy costs of hypersonic transport can be lower than those of conventional transport while slashing journey times.

Stratolaunch Roc can be used to launch hypersonic aircraft.Camille Fin
(20 Jan 2023) The biggest plane in the world has wings longer than a football field. See its latest flight
/ref>

Hermeus demonstrated transition from turbojet aircraft engine operation to ramjet operation on 17 November 2022, thus avoiding the need to boost aircraft velocities by rocket or scramjet.Valerie Insinn
(28 Mar 2024) Hermeus rolls out new uncrewed aircraft as company edges toward goal of hypersonic flight
/ref>

:''See: SR-72, § Mayhem''

Weapons

Two main types of hypersonic weapons are hypersonic cruise missiles and hypersonic glide vehicles. Hypersonic weapons, by definition, travel five or more times the speed of sound. Hypersonic cruise missiles, which are powered by scramjets, are limited to below ; hypersonic glide vehicles can travel higher.

Hypersonic vehicles are much slower than ballistic (i.e. sub-orbital or fractional orbital) missiles, because they travel in the atmosphere, and ballistic missiles travel in the vacuum above the atmosphere. However, they can use the atmosphere to manoeuvre, making them capable of large-angle deviations from a ballistic trajectory. A hypersonic glide vehicle is usually launched with a ballistic first stage, then deploys wings and switches to hypersonic flight as it re-enters the atmosphere, allowing the final stage to evade existing missile defense systems which were designed for ballistic-only missiles.Mark Zastrow (2021-11-04)
"How does China's hypersonic glide vehicle work?"
Astronomy

According to a CNBC July 2019 report (and now in a CNN 2022 report), Russia and China lead in hypersonic weapon development, trailed by the United States,CN
(1 Jun 2022) Russia and China are ahead of US in hypersonic missile technology. Here's why
/ref>Valerie Insinn
(2 Jun 2022) Lockheed’s CEO wants to fund a hypersonic wind tunnel, but says DoD isn’t buying in
/ref>Stephen Carlson (14 Nov 2018) DARPA issues contract proposition for hypersonic missile defenseStephen Carlson (13 Nov 2018) Space, lasers, hypersonic missiles rank high for U.S. missile defense research
/ref> and in this case the problem is being addressed in a joint program of the entire Department of Defense.Sydney Freedberg, Jr. To meet this development need, the US Army is participating in a joint program with the US Navy and Air Force, to develop a hypersonic glide body. India is also developing such weapons. France and Australia may also be pursuing the technology. Japan is acquiring both scramjet (Hypersonic Cruise Missile), and boost-glide weapons (Hyper Velocity Gliding Projectile).

China

China's XingKong-2 (星空二号, ''Starry-sky-2''), a waverider, had its first flight 3 August 2018.Holmes Liao (8 Oct 2021) China's Development of Hypersonic Missiles and Thought on Hypersonic Defense Publication: China Brief Volume: 21 Issue: 19
Critique of JF-12 hypersonic wind tunnel, as well as the newer JF-22 detonation-driven ultra-high-speed and high-enthalpy shock tunnel (used for XingKong). "PLA strategists fear that the U.S. may deploy hypersonic weapons on the first island chain and/or the second island chain, directly threatening China."
In August 2021 China launched a boost-glide vehicle to low-earth orbit, circling Earth before maneuvering toward its target location, missing its target by two dozen miles.Tyler Rogowa
(16 Oct 2021) China Tested A Fractional Orbital Bombardment System That Uses A Hypersonic Glide Vehicle: Report
/ref> However China has responded that the vehicle was a spacecraft, and not a missile;Hannah Ritchie, CN

/ref> there was a July 2021 test of a spaceplane, according to Chinese Foreign Ministry Spokesperson Zhao Lijian;Demetri Sevastopulo, Washingto
(OCTOBER 20 2021) China conducted two hypersonic weapons tests this summer
/ref> Todd Harrison points out that an orbital trajectory would take 90 minutes for a spaceplane to circle Earth (which would defeat the mission of a weapon in hypersonic flight). The US DoD's headquarters (The Pentagon) reported in October 2021 that two such hypersonic launches have occurred; one launch did not demonstrate the accuracy needed for a precision weapon; the second launch by China demonstrated its ability to change trajectories, according to Pentagon reports on the 2021 competition in arms capabilities.David E Sanger, and William J Broad ''The New York Times'' (28 Oct 2021) "China, Testing New Weapon, Jolts Pentagon"

In 2022, China unveiled two more hypersonic models.Mike Ye
(10 Nov 2022) China displays air-launched hypersonic missile at air show near Taiwan
Mockups of 2PZD-21 thought to be air-launched versions of YJ-21Tanmay Kada
(13 Nov 2022) China Unveils World's 1st Carrier-Based Hypersonic Anti-Ship Missile 'YJ-21' That Can 'Strike The Eagle'
"China has finally unveiled its 'YJ-21', or the 'Eagle Strike 21' shipborne hypersonic anti-ship missile that has long been shrouded in mystery. The missile has been put on display at the ongoing Zhuhai Air Show". An AI simulation has revealed that a Mach 11 aircraft can simply outrun a Mach 1.3 fighter attempting to engage it, while firing its missile at the "pursuing" fighter.Stephen Chen, SCM
(28 Feb 2023) Chinese AI simulates hypersonic air battle, offering surprising tactic for winning Mach 11 dogfight
/ref> This strategy entails a fire control system to accomplish an over-the-shoulder missile launch, which does not yet exist (2023).

In February 2023, the DF-27 covered in 12 minutes, according to leaked secret documents.Geoff Ziezulewic
(18 Apr 2023) Pentagon: Yes, we are still lagging behind China's hypersonics
DF-27 The capability directly threatens Guam, and US Navy aircraft carriers.

Russia

In 2016, Russia is believed to have conducted two successful tests of Avangard, a hypersonic glide vehicle. The third known test, in 2017, failed. In 2018, an Avangard was launched at the Dombarovskiy missile base, reaching its target at the Kura shooting range, a distance of . Avangard uses new composite materials which are to withstand temperatures of up to . The Avangard's environment at hypersonic speeds reaches such temperatures."Putin Says 'Invulnerable' New Hypersonic Nuclear Missile Is Ready For Deployment"
''The Huffington Post'', 27 December 2018 Russia considered its carbon fiber solution to be unreliable, and replaced it with new composite materials. Two Avangard hypersonic glide vehicles (HGVs) will first be mounted on SS-19 ICBMs; on 27 December 2019 the weapon was first fielded to the Yasnensky Missile Division, a unit in the Orenburg Oblast. In an earlier report, Franz-Stefan Gady named the unit as the 13th Regiment/Dombarovskiy Division (Strategic Missile Force).Franz-Stefan Gady (14 November 2019) Russia: Avangard Hypersonic Warhead to Enter Service in Coming Weeks
"The Russian Strategic Missile Force will receive the first two ICBMs fitted with the Avangard warhead in late November or early December." The Avangard HGV was codenamed Yu-71, under Project 4202. "In late November – early December, two UR-100N UTTKh missiles equipped with the hypersonic glide vehicles from the first regiment of Avangard systems will assume experimental combat duty in the Dombarovsky division of the Strategic Missile Force,"—''Tass'', 13 November. The "13th regiment will reportedly be the first unit to receive the two retrofitted SS-19 ICBMs. The regiment is part of the Dombarovskiy (Red Banner) missile division". Eventually 4 more SS-19s fitted with Avangard HGVs will join the 13th Regiment; a second regiment with six Avangard / SS-19s will be stood up by 2027.
In 2021 Russia launched a 3M22 Zircon antiship missile over the White Sea, as part of a series of tests.A
(29 Nov 2021) Russian Navy test-fires hypersonic missile in the White Sea
/ref> " Kinzhal and Zircon (Tsirkon) are standoff strike weapons".Roger McDermot
(7 Feb 2022) The Role of Hypersonic Weapons in Russian Military Strategy
Giperzvukovogo Oruzhiya—(GZO); or Giperzvukovyye letatel’nyye apparaty—(GZLA) Kinzhal, Tsirkon, Kalibr, Poseidon, Avangard, Burevestnik, Sarmat, In February 2022, a coordinated series of missile exercises, some of them hypersonic, were launched on 18 February 2022 in an apparent display of power projection. The launch platforms ranged from submarines in the Barents sea in the Arctic, as well as from ships on the Black sea to the south of Russia. The exercise included a RS-24 Yars ICBM, which was launched from the Plesetsk Cosmodrome in Northern Russia until it reached its destination on the Kamchatka Peninsula in Eastern Russia.CN
(19 Feb 2022)
/ref> Ukraine estimated a 3M22 Zircon was used against it, but apparently did not exceed Mach 3 and was shot down 7 February 2024 in Kyiv.Lewis Pag
Russia's 'Zircon' hypersonic super weapon has failed in Ukraine. Putin is egg-faced again
/ref>

United States

These tests have prompted US responses in weapons development.Prakash Nanda, ''Eurasian Times'
(6 Nov 2022) Hypersonic Hype? This Is Why US 'Trails' Russia, China & Even North Korea In Hypersonic Missile Development
/ref> By 2018, the AGM-183"Lockheed Martin gets a second hypersonic weapons contract, this time for $480 million, as the US tries to keep pace with Russia and China"
14 August 2018, CNBC-- $480 million and Long-Range Hypersonic Weapon were in development per John Hyten's USSTRATCOM statement on 8 August 2018 (UTC).USSTRATCOM
CNBC At least one vendor is developing ceramics to handle the temperatures of hypersonics systems.Nick Stockton (27 December 2018)
"Rotating Detonation Engines Could Propel Hypersonic Flight"
''Wired'' There are over a dozen US hypersonics projects as of 2018, notes the commander of USSTRATCOM;Colin Clar
(28 Oct 2021) 'Hundreds' Of China Hypersonic Tests Vs. 9 US; Hyten Says US Moves Too Slowly
/ref>Sydney Freedberg (13 March 2019)
"Hypersonics Won't Repeat Mistakes Of F-35"
Breaking Defense
*"Navy: Conventional Prompt Strike (CPS)"
*"Army: Land-Based Hypersonic Missile"
*"Air Force: HCSW and ARRW"
*"DARPA & Air Force: Tactical Boost-Glide (TBG) and Hypersonic Air-breathing Weapon Concept (HAWC)"
Joseph Trevithick (6 September 2018)
"DARPA Starts Work On 'Glide Breaker' Hypersonic Weapons Defense Project"
The Drive
Patrick Tucker (13 January 2020) The US Wants to Intimidate China with Hypersonics, Once It Solves the Physics
2020 reviewJoseph Trevithic (6 August 2019)
"Air Force Reveals Tests Of Supposed Record-Setting Scramjet Engine From Northrop Grumman"
/ref> from which a future hypersonic cruise missile is sought, perhaps by Q4 FY2021.THERESA HITCHENS and AARON MEHTA Valerie Insinn
(20 Dec 2021) Air Force hypersonic weapon runs into trouble after a third failed test
/ref> The Long range precision fires (LRPF) CFT is supporting Space and Missile Defense Command's pursuit of hypersonics. Joint programs in hypersonics are informed by Army work; however, at the strategic level, the bulk of the hypersonics work remains at the Joint level. Long Range Precision Fires (LRPF) is an Army priority, and also a DoD joint effort. The Army and Navy's Common Hypersonic Glide Body (C-HGB) had a successful test of a prototype in March 2020.Sydney J. Freedberg Jr. (20 Mar 2020) Hypersonics: Army, Navy Test Common Glide Body
"The U.S. Navy and U.S. Army jointly executed the launch of a common hypersonic glide body (C-HGB), which flew at hypersonic speed to a designated impact point. "
DoD (20 March 2020) Department of Defense tests hypersonic glide body
"The C-HGB – when fully fielded – will comprise the weapon's conventional warhead, guidance system, cabling, and thermal protection shield." Also: comments from LTG L. Neill Thurgood RCCTOJon Harper (4 March 2020) JUST IN: Pentagon to Spend Billions Mass-Producing Hypersonic Weapons
"Aero shells that provide thermal protection for the high-speed platforms will be a key component of the systems" A wind tunnel for testing hypersonic vehicles was completed in Texas (2021).University Strategic Communications (18 May 2021

At long and weighing more than , it operates at the UTSA Hypersonics Lab The Army's Land-based Hypersonic Missile "is intended to have a range of ". Justin Kat
(2 Feb 2022) Pentagon developing ‘National Defense Science and Technology’ strategy: Memo
14 technologiesBrandi Vincen
(4 Feb 2022) Pentagon Previews New Tech Strategy, Updates Priorities List
for upcoming National Defense Science and Technology StrategyCourtney Albon and Joe Goul
(4 Feb 2022) Top Pentagon officials met with industry executives about hypersonics. What comes next?
a range of concernsNaval News Staf
(1 Nov 2022) Hypersonic Missiles: Evolution Or Revolution?
summary overview By adding rocket propulsion to a shell or glide body, the joint effort shaved five years off the likely fielding time for hypersonic weapon systems.Gary Sheftick Sydney J. Freedberg Jr. (11 September 2018) Aiming The Army's Thousand-Mile Missiles
Multi-domain Ft Sill Countermeasures against hypersonics will require sensor data fusion: both radar and infrared sensor tracking data will be required to capture the signature of a hypersonic vehicle in the atmosphere. There are also privately developed hypersonic systems, as well as critics.Shannon Bugos Ashish Dangwal

DoD tested a Common Hypersonic Glide Body (C-HGB) in 2020. The Air Force dropped out of the tri-service hypersonic project in 2020, leaving only the Army and Navy on the C-HGB.
payload; maneuverability at Mach 5 is an issue; possible red herring for fundingJOSEPH TREVITHICK $928 million
According to Air Force chief scientist, Dr. Greg Zacharias, the US anticipates having hypersonic weapons by the 2020s, hypersonic drones by the 2030s, and recoverable hypersonic drone aircraft by the 2040s. The focus of DoD development will be on air-breathing boost-glide hypersonics systems.David Vergun (14 December 2018)
"DOD scaling up effort to develop hypersonics"
U.S. Army Countering hypersonic weapons during their cruise phase will require radar with longer range, as well as space-based sensors, and systems for tracking and fire control. A mid-2021 report from the Congressional Research Service states the United States is "unlikely" to field an operational hypersonic glide vehicle (HGV) until 2023.

On 21 October 2021, the Pentagon stated that a test of a hypersonic glide body failed to complete because its booster failed; according to Lt. Cmdr. Timothy Gorman the booster was not part of the equipment under test, but the booster's failure mode will be reviewed to improve the test setup.Caitlin M Kenne
One of Four Boosters Fails in Rapid-Fire Hypersonic Tests
/ref> The test occurred at Pacific Spaceport Complex – Alaska, on Kodiak island.Oren Lieberman
(21 October 2021, updated 22 Oct 21) Latest US military hypersonic test fails
/ref> Three rocketsondes at Wallops Island completed successful tests earlier that week, for the hypersonics effort. On 29 October 2021, the booster rocket for the Long-Range Hypersonic Weapon was successfully tested in a static test; the first stage thrust vector control system control system was included.Mike Ston
(29 Oct 2021) U.S. successfully tests hypersonic booster motor in Utah
/ref> On 26 October 2022, Sandia National Laboratories conducted a successful test of hypersonic technologies at Wallops Island.Mike Stone, Reuter
(26 October 2022) Pentagon successfully flight tests hypersonic weapon components
some 11 experiments: hypersonic communication and navigation equipment; materials that can withstand the atmospheric heating at hypersonic speedsNaval News Staff
(28 October 2022) U.S. DoD Continues To Advance Hypersonic Capabilities
/ref> On 28 June 2024, DoD announced a successful recent end-to-end test of the US Army's Long-Range Hypersonic Weapon all-up round (AUR) and the US Navy's Conventional Prompt Strike. The missile was launched from the Pacific Missile Range Facility, Kauai, Hawaii.US Department of Defens
(28 Jun 2024) DOD Completes Flight Test of Hypersonic Missile
/ref>

In September 2021, and in March 2022, US defense contractors Raytheon/Northrop Grumman, and Lockheed respectively, first successfully tested their air-launched, scramjet-powered hypersonic cruise missiles, which were funded by DARPA. By September 2022 Raytheon was selected for fielding Hypersonic Attack Cruise Missile (HACM), a scramjet-powered hypersonic missile by FY2027.Audrey Decke
(28 Mar 2023) Failed Hypersonic Test Dims Air Force View of Lockheed Missile
Air Force R&D funding for ARRW and HACM tests is $150 million and $380 million, respectively. "ARRW and HACM are just two of the U.S. military's hypersonic efforts; in all, the Pentagon is requesting $11 billion for hypersonic R&D in 2024"

In March 2024, Stratolaunch Roc launched TA-1, a vehicle which is nearing Mach 5 at in a powered flight, a risk-reduction exercise for TA-2.Passant Rabi
(11 March 2024) Watch as World’s Largest Plane Releases Hypersonic Vehicle for Its First Powered Test Flight
/ref> In a similar development, Castelion launched its low-cost hypersonic platform in the Mojave desert, in March 2024.Mike Ston
(11 March 2024) Hypersonic weapon startup Castelion has first prototype missile test
/ref>

In 2021, DoD was codifying flight test guidelines, knowledge gained from Conventional Prompt Strike (CPS), and the other hypersonics programs,Sydney Freedberg, Jr. for some 70 hypersonics R&D programs alone, as of 2021.Nathan Strout (5 Oct 2020) SpaceX, L3 to provide hypersonic tracking satellites for Space Development Agency
SDA's National Defense Space Architecture ( NDSA) In 2021–2023, Heidi Shyu, the Under Secretary of Defense for Research and Engineering (USD(R&E)) pursued a program of annual rapid joint experiments,Courtney Albo
(27 Oct 2022) Pentagon’s Shyu, LaPlante push to get critical tech into production
"Senators may halve request for Rapid Defense Experimentation Reserve funding without transition plan" (RDER funding for DoD R&E, A&S projects) including hypersonics capabilities, to bring down the cost of development.Tate Nurki
(9 Feb 2022) To catch China and Russia in hypersonic race, US must embrace risk now
/ref> A hypersonic test bed aims to bring the frequency of tests to one per week.Courtney Albon
(8 Nov 2022) Pentagon test bed to ramp up development of hypersonics
MACH-TBCourtney Albo
(6 Jan 2023) Pentagon racing to restore US superiority in hypersonics
Test Resource Management Center (TRMC) SkyRange seeks to convert 24 Global Hawks for testing hypersonics.

Iran

In 2022, Iran was believed to have constructed their first hypersonic missile. Amir Ali Hajizadeh, the commander of the Air Force of the Islamic Republic of Iran's Revolutionary Guards Corps, announced the construction of the Islamic Republic's first hypersonic missile. He noted: "This new missile was produced to counter air defense shields and passes through all missile defense systems and which represents a big leap in the generation of missiles" and has a speed above Mach 13. but Col. Rob Lodwick, the spokesman for the Pentagon on Middle East affairs said that there are doubts in this regard.

Other programs

France, Australia, India,World Affair
(22 Oct 2021) India Is One Of The Few Countries Working On Hypersonic Missiles : U.S. Congressional report
BrahMos 2 Germany, Japan, South Korea, North Korea, and Iran also have ongoing hypersonic weapon projects or research programs.

Australia and the US have begun joint development of air-launched hypersonic missiles, as announced by a Pentagon statement on 30 November 2020. The development will build on the $54 million Hypersonic International Flight Research Experimentation (HIFiRE) under which both nations collaborated on over a 15-year period. Small and large companies will all contribute to the development of these hypersonic missiles, named SCIFIRE in 2022.Colin Clar
(25 Jan 2022) Aussies unveil new hypersonics center, signal distance from Ukraine crisis
/ref>Stephen Lose
(22 Sep 2022) Raytheon wins $985M contract to develop hypersonic missile
HACM possible fielding by FY2027

Defenses

In May 2023 Ukraine shot down a Kinzhal with a Patriot.Patrick Tucke
(20 Sep 2023) Ukraine downed a hypersonic missile with a Patriot. What that says about the future of weapons
/ref> IBCS, or the Integrated Air and Missile Defense Battle Command System is an Integrated Air and Missile Defense (IAMD) capability designed to work with Patriots and other missiles.

;Rand 2017 assessment
Rand Corporation (28 September 2017) estimates there is less than a decade to prevent Hypersonic Missile proliferation.
In the same way that anti-ballistic missiles were developed as countermeasures to ballistic missiles, counter-countermeasures to hypersonics systems were not yet in development, as of 2019.Amanda Macias (21 March 2018)
"Russia and China are 'aggressively developing' hypersonic weapons — here's what they are and why the US can't defend against them: America's top nuclear commander said the U.S. doesn't have defenses against hypersonic weapons. Russia and China are leading the way in developing hypersonic weapons."
CNBC
Arie Egozi Amanda Macias (12 October 2018)

CNBCSydney Freedberg (1 February 2019
"Pentagon Studies Post-INF Weapons, Shooting Down Hypersonics"
Breaking Defense ''See the National Defense Space Architecture (2021), above.'' But by 2019, $157.4 million was allocated in the FY2020 Pentagon budget for hypersonic defense, out of $2.6 billion for all hypersonic-related research.Kelley M. Sayler (11 July 2019)
"Hypersonic Weapons: Background and Issues for Congress"
Congressional Research Service $207 million of the FY2021 budget was allocated to defensive hypersonics, up from the FY2020 budget allocation of $157 million.Theresa Hitchens Government Accountability Officebr>(Mar 2021) Hypersonic Weapons
DOD Should Clarify Roles and Responsibilities to Ensure Coordination across Development Efforts, recommendation gao-21-378 Both the US and Russia withdrew from the Intermediate-Range Nuclear Forces (INF) Treaty in February 2019. This will spur arms development, including hypersonic weapons, in FY2021 and forward.Sebastien Roblin (30 April 2020) The Pentagon Plans to Deploy An Arsenal Of Hypersonic Weapons In The 2020s
Army LRHW, Navy C-HGB, Air Force HSW-ab By 2021 the Missile Defense Agency was funding regional countermeasures against hypersonic weapons in their glide phase.Theresa Hitchens (12 Aug 2021) Next Budget Will Limit Glide Phase Interceptor Contractors: MDA Head
2028 target date is being accelerated. FY2022 decisions on GPI/Ground-Based Interceptor, GBI replacement (the Next generation interceptor NGI) will be made by Deputy Secretary Kathleen Hicks.BRETT TINGLEY AND JOSEPH TREVITHICK (19 JUNE 2021) Missile Defense Agency Lays Out How It Plans To Defend Against Hypersonic ThreatsMissile Defense Agency (16 Jun 2021) MDA Concept for Regional Hypersonic Missile Defense: Technology to Defeat the Threat
GPI scenario animation 7:51 James Acton characterized the proliferation of hypersonic vehicles as never-ending in October 2021; Jeffery Lewis views the proliferation as additional arguments for ending the arms race.Jeff Brumfiel (20 Oct 2021) Behind murky claim of a new hypersonic missile test, there lies a very real arms race
Michael Griffin comments Doug Loverro assesses that both missile defense and competition need rethinking.Theresa Hitchen
(21 Oct 2021) Hypersonic Space Test Fuels Sino-American Arms Race
/ref> CSIS assesses that hypersonic defense should be the US' priority over hypersonic weapons.Center for Strategic & International Studie
(7 Feb 2022) Complex Air Defense: Countering the Hypersonic Missile Threat
Dr. Tom Karako, Director of the CSIS Missile Defense Project; Ms. Kelley Sayler, CRS; Dr. Gillian Bussey, Director of the Joint Hypersonics Transition Office; Dr. Mark Lewis, Executive Director of NDIA's Emerging Technologies Institute; Mr. Stan Stafira, Chief Architect at the Missile Defense Agency (MDA)Theresa Hitchen
(7 Feb 2022) Pentagon needs to prioritize hypersonic defense, not offense: CSIS
/ref>Congressional Research Servic
(2 May 2023) Hypersonic Missile Defense: Issues for Congress
IF11623

NDSA / PWSA

As part of their Hypersonic vehicle tracking mission, the Space Development Agency (SDA) launched four satellites and the Missile Defense Agency (MDA) launched two satellites on 14 February 2024 (launch USSF-124).Sandra Erwi
(14 February 2024) SpaceX launches U.S. missile-defense satellites
/ref>Courtney Albo
(14 Feb 2024) Pentagon launches six satellites to boost missile tracking capability
/ref> The satellites will share the same orbit, which allows the SDA's wide field of view (WFOV) satellites and the MDA's medium field of view (MFOV) downward-looking satellites to traverse the same terrain of Earth. The SDA's four satellites are part of its Tranche 0 tracking layer (T0TL). The MDA's two satellites are HBTSS or Hypersonic and ballistic tracking space sensors.

Additional capabilities of Tranche 0 of the National defense space architecture (NDSA), also known as the Proliferated warfighting space architecture (PWSA) will be tested over the next two years.Masao Dahlgre
(13 Feb 2024) The Pentagon's next satellite launch is a test for missile defense's future
/ref>

Proposed

; Aircraft:

* I-Plane
* 14-X
* Espadon hypersonic combat aircraft concept (program conducted by the ONERA)
* Avatar (spacecraft)
* Advanced Technology Vehicle
* DARPA XS-1
* Destinus hydrogen-powered hypersonic aircraft. A prototype was tested last year.
* Dream Chaser
* NASA X-43
* HyperSoar
* HyperStar hypersonic passenger airliner
* Falcon HTV-2
* Boeing Commercial Airplanes hypersonic airliner Concept
* Lockheed Martin SR-72
* Kholod
* Ayaks waverider spaceplane
* Programme for Reusable In-orbit Demonstrator in Europe (PRIDE)
* Sänger II
* HyShot
* Hytex
* Horus
* SHEFEX
* Skylon
* Reaction Engines A2
* Hypersonic Air Vehicle Experimental (HVX) with Concept V aircraft
* Spartan
* HEXAFLY
* SpaceLiner
* STRATOFLY
* Zero Emission Hyper Sonic Transport
* Hermeus Quarterhourse unmanned hypersonic demonstrator designed to land and take-off on conventional runways.
* Hermeus Halcyon hypersonic transport
* Venus Aerospace ''Stargazer'' hypersonic airlinerJeff Spr
(29 Jun 2022) Venus Aerospace unveils its dart-like Mach 9 plane design
meant to operate at 32 mile altitude at 7000 mph. with rotating detonation rocket engineprnewswir
(27 Oct 2022) Venus Aerospace Benchmarks New Hypersonic Engine
/ref>Scott Manle
(2021) What Is A Rotating Detonation Engine - And Why Are They Better Than Regular Engines
/ref>
* POLARIS Raumflugzeuge GmbH is developing and testing a hypersonic spaceplane for the German Armed Forces in Peenemünde

; Bombers:
* Expendable Hypersonic Air-Breathing Multi-Mission Demonstrator ("Mayhem") Based on § HAWC and HSSW: "solid rocket-boosted, air-breathing, hypersonic conventional cruise missile", a follow-on to AGM-183A. As of 2020 no design work had been done. By 2022 Mayhem was to be tasked with ISR and strike missions,Joseph Trevithick
(16 Dec 2022) Mayhem Hypersonic Strike-Recon Jet Contract Awarded To Leidos
"Mayhem air vehicle to demonstrate strike and intelligence-gathering capabilities" as a possible bomber.Kris Osbor
(10 Jan 2023) Air Force Research Lab Advances "First-of-its-Kind" Armed Hypersonic Attack Drone
"The new hypersonic vehicle, called Mayhem, will perform surveillance and 'strike' missions" Leidos is preparing a system requirements review, and a conceptual design for these missions.CHRISTOPHER PLAI
(21 Dec 2022) THE U.S. AIR FORCE IS PREPARING TO UNLEASH HYPERSONIC MAYHEM
AFRL project; design package to be ready by 2027 Draper Labs has begun a partnership with Leidos.Darren Or
(20 Jan 2023) Project Mayhem, the Air Force's Secret Hypersonic Bomber, Has Begun Cooking
/ref> Kratos is preparing a conceptual design for Mayhem, using Air Force Research Laboratory (AFRL) digital engineering techniques in a System design agent team, a collaboration with Leidos, Calspan, and Draper.Christopher McFadden
(20 Jan 2023) US' hypersonic missile 'Mayhem' gets a boost from Kratos
/ref> DIU is soliciting additional Hypersonic and High-Cadence Airborne Testing Capabilities (HyCAT), for Mayhem.Theresa Hitchen
(24 Jan 2023) DIU asks industry for help getting hypersonic test jet closer to lift off
/ref>

; Cruise missiles:
* Advanced Hypersonic Weapon (AHW)
* Hypersonic Air-breathing Weapon Concept (HAWC, pronounced "hawk"). September 2021: HAWC is DARPA-funded. Built by Raytheon and Northrop Grumman, HAWC is the first US scramjet-powered hypersonic missile to successfully complete a free flight test in the 2020s.BreakingDefens
(18 Apr 2022) Air-breathing hypersonics: A new tactical capability to counter evolving threats
"For HAWC, that program of record will be the Air Force’s Hypersonic Attack Cruise Missile, or HACM"
* ttps://breakingdefense.com/2021/09/darpa-hypersonic-cruise-missile-prototype-flies-at-last/ Theresa Hitchens (27 Sep 2021) DARPA Hypersonic Cruise Missile Prototype Flies At Last/ref>Aviation Wee
(30 Sep 2021) Raytheon Ends Air-Launched Hypersonic Vehicle Test Drought
/ref> DARPA's goals for the test, which were successfully met, were: "vehicle integration and release sequence, safe separation from the launch aircraft, booster ignition and boost, booster separation and engine ignition, and cruise". HAWC is capable of sustained, powered maneuver in the atmosphere.World'sTech HAWC appears to depend on a rocket booster to accelerate to scramjet velocities operating in an oxygen-rich environment.Kris Osborn (1 October 2019)
"Air Force arms B1-B bomber with hypersonic weapons"
Fox News It is easier to put a seeker on a sub-sonic air-breathing vehicle. In mid-March 2022 a HAWC Scramjet was successfully tested in an air-launched flight by a second vendor.Oren Lieberman

Both the Raytheon and the Lockheed teams have now successfully tested their scramjetsAlex Holling
(5 Apr 2022) US SUCCESSFULLY TESTS SCRAMJET-POWERED HYPERSONIC MISSILE IN SECRET
"speeds just above Mach 5 at an altitude higher than 65,000 feet for more than 300 miles" On 18 July 2022 Raytheon announced another successful test of its Hypersonic Air-breathing Weapon Concept (HAWC) scramjet, in free flight.Mike Ston
(18 Jul 2022) U.S. successfully flight-tests Raytheon hypersonic weapon -Pentagon
/ref>Audrey Decke
(14 Mar 2024) Air Force Won’t Buy Hypersonic Missiles in 2024, Official Says
/ref>
*#MoHAWC is a follow-on to DARPA's HAWC project. MoHAWC will seek "to further develop the vehicle’s scramjet propulsion system, upgrade integration algorithms, reduce the size of navigation components, and improve its manufacturing approach".Courtney Albo
(9 May 2022) DARPA seeks funding for next phase of hypersonic weapon
/ref>
* Hypersonic Conventional Strike Weapon (HCSW - pronounced "hacksaw") passed its critical design review (CDR)GlobalSecurity.or

/ref> but this IDIQ (indefinite duration, indefinite quantity) contract was terminated in favor of ARRW because twice as many ARRWs will fit on a bomber.John A. Tirpa
(2 Mar 2020) Roper: The ARRW Hypersonic Missile Better Option for USAF
/ref>
* ASN4G (air-launched, scramjet-powered, hypersonic cruise missile under development by MBDA France and the ONERA to succeed the ASMP)
* Kh-45 (cancelled)
* Zircon
* Hypersonic Technology Demonstrator Vehicle
*/ Brahmos-II
* Hycore

; Glide vehicles:
* AGM-183A air launched rapid response weapon (ARRW, pronounced "arrow")Chris Martin (17 December 2019
"Lockheed awards $81.5M contract for hypersonic missile motor"
Defense News, HCSW $81.5M, ARRWTheresa Hitchens (27 February 2020) Lockheed Martin, Air Force Press Ahead On Air-Launched Hypersonic Missile
=HSW-ab; ARRW funding is augmented; Telemetry data has been successfully transmitted from ARRW —AGM-183A IMV-2 (Instrumented Measurement Vehicle) to the Point Mugu ground stations, demonstrating the ability to accurately broadcast radio at hypersonic speeds;Military T
(14 Feb 2021) AGM 183A Arrow U.S Long-range Hypersonic Missile
ARRW however, ARRW's launch sequence was not completed, as of 15 Dec 2021.Miltech insight
(18 Dec 2021) Third Test of US Hypersonic Missile AGM-183A Arrow Fails
/ref>STEFANO D'URSO Hundreds of ARRWs or other Hypersonic weapons are being sought by the Air Force. On 9 March 2022 Congress halved funding for ARRW and transferred the balance to ARRW's R&D account to allow for further testing, which puts the procurement contract at risk.Valerie Insinn
(9 Mar 2022) Air Force can’t buy its first hypersonic ARRW as planned, following budget cut
/ref> A production decision on ARRW has been delayed for a year to complete flight testing.Stephen Lose
(17 Jul 2022) US Air Force weighing future of key hypersonic program after two successful tests
/ref>Oren Liebermann

AGM-183A ARRW On 14 May 2022 an ARRW flight test was successfully completed, for the first time.Oren Lieberman

/ref>Valerie Insinn
(9 Dec 2022) Air Force successfully tests first fully-operational air-launched hypersonic missile
AGM-183A ARRW's 1st all-up round was successfully tested, completing its flight path and successfully detonating, after 3 consecutive test failures (Apr, Jul, and Dec 2021), and 2 successful tests of the booster in May and July 2022 There have been 3 successful tests of ARRW in 2022; however the Air Force is requiring 3 additional successful tests of an All-Up Round (AUR) before making a production decision.John A Tirpa
(14 Dec 2022) Three More Successful All-Up ARRW Tests Required Before Production Decision
Air Force: "Three more 'all-up' flight tests of the AGM-183 Air-launched Rapid Response Weapon (ARRW) must succeed". No production decision will be made in 2024. The USAF now intends to end the ARRW development program, as of 29 March 2023.Bloomber
(29 Mar 2023) US Air Force Plans to End Lockheed Hypersonic Weapon Program
/ref>Michael Marro
(24 Mar 2023) Air Force mum on whether latest ARRW hypersonic test was successful
/ref>Michael Marro
(22 Aug 2023) Air Force won't say whether newest ARRW test succeeded, echoing past failure
An end-to-end test of a Middle Tier Acquisition (MTA) from LockheedStephen Lose
(21 Aug 2023) US Air Force fires hypersonic ARRW in first test since March failure
End-to-end test A B-52 flying out of Anderson AFB in Guam fired an All-Up-Round AGM-183A Air-launched Rapid Response Weapon (ARRW); the AUR was tested at Reagan test site in the Pacific on 17 March 2024.Brad Lendo

/ref>
* DARPA Tactical Boost Glide vehicle
* VMaX-2 hypersonic glide vehicle (under development by ArianeGroup; first flight test scheduled for 2025)
* HGV-202F

Flown

; Aircraft:
* North American X-15 (crewed)
* Lockheed X-17
* NASA X-43
* Boeing X-51
* HSTDV

; Glide vehicles:
* Avangard
* DF-ZF
* Hwasong-8
* '' Hwasong-12A'' (official designation unconfirmed)
* Hwasong-16B
* Unnamed
* VMaX (developed by ArianeGroup; first flight test took place on 26 June 2023 and was a success)

; Spaceplanes:
* Space Shuttle orbiter (crewed)
* '' Buran'' (human-rated, only flew without crew)
* RLV-TD
* Boeing X-37
* Shenlong
* IXV
* BOR-4
* Martin X-23 PRIME
* ASSET
* HYFLEX
* Reusable experimental spacecraft (disputed)
* Jiageng-1

Cancelled

; Aircraft:
* Silbervogel (Sänger bomber)
* Keldysh bomber
* Tupolev Tu-360, follow-on to Tu-160
* Tupolev Tu-2000
* Lockheed L-301

; Glide vehicles
* VERAS (hypersonic glide vehicle program launched in 1965 and cancelled in 1971)

; Spaceplanes:
* Boeing X-20 Dyna-Soar
* Rockwell X-30 (National Aerospace Plane)
* Orbital Sciences X-34
* Mikoyan-Gurevich MiG-105
* Tsien Spaceplane 1949
* HOPE-X
* XCOR Lynx
* Lockheed Martin X-33
* Hermes
* Prometheus
* HL-20 Personnel Launch System
* HL-42
* BAC Mustard
* Kliper
* HOTOL
* Valier Raketenschiff
* Rockwell C-1057

See also

* Hypersonic effect
* Supersonic transport
*Lifting body
* List of X-planes
* Thunderbird 1

Notes

References

Further reading

*David Wright and Cameron Tracy, "Over-hyped: Physics dictates that hypersonic weapons cannot live up to the grand promises made on their behalf", ''Scientific American'', vol. 325, no. 2 (August 2021), pp. 64–71. Quote from p. 71: "Failure to fully assess he potential benefits and costs of hypersonic weaponsis a recipe for wasteful spending and increased global risk."

External links

{{Library resources box

A comparative analysis of the performance of long-range hypervelocity vehicles(2022) Joint Air Power Competence Centre
(JAPCC)

Aerodynamics
Aerospace engineering
Airspeed