Hypersonic flight
[1] Hypersonic vehicles are able to maneuver through the atmosphere in a non-parabolic trajectory, but their aerodynamic heat loads need to be managed.
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.
[3] In November 1961, Air Force Major Robert White flew the X-15 research aircraft at speeds over Mach 6.
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 for further study during the 21st century, and strategic competition between the United States, India, Russia, and China.
A shock wave forms, which deflects the air from the stagnation point and insulates the flight body from the atmosphere.
When this flow enters a boundary layer, there are high viscous effects due to the friction between air and the high-speed object.
Therefore, hypersonic boundary layers are high temperature regions due to the viscous dissipation of the flow's kinetic energy.
For a given aerodynamic condition low-density effects depends on the value of a nondimensional parameter called the Knudsen number
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.
The overall effect of this interaction is to create a much higher skin friction than normal, causing greater surface heat flow.
[13] The entropy layer is a region of large velocity gradients caused by the strong curvature of the shock wave.
[11] 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.
[11] Japan is acquiring both scramjet (Hypersonic Cruise Missile), and boost-glide weapons (Hyper Velocity Gliding Projectile).
[57][58] However China has responded that the vehicle was a spacecraft, and not a missile;[59] there was a July 2021 test of a spaceplane, according to Chinese Foreign Ministry Spokesperson Zhao Lijian;[60][61][62] 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).
[68] In 2018, an Avangard was launched at the Dombarovskiy missile base, reaching its target at the Kura shooting range, a distance of 5,955 km (3,700 mi).
[70] Two Avangard hypersonic glide vehicles (HGVs)[72] 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.
[72] In 2021 Russia launched a 3M22 Zircon antiship missile over the White Sea, as part of a series of tests.
[87][88][89] The Long range precision fires (LRPF) CFT is supporting Space and Missile Defense Command's pursuit of hypersonics.
[94] The Army and Navy's Common Hypersonic Glide Body (C-HGB) had a successful test of a prototype in March 2020.
[102]: p.6 [49][103][104][105][106] 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.
[123] 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.
[129] On 26 October 2022 Sandia National Laboratories conducted a successful test of hypersonic technologies at Wallops Island.
[130][131] 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.
[132] In September 2021, and in March 2022, US vendors Raytheon/Northrop Grumman,[133][134][135] and Lockheed[136][137] respectively, first successfully tested their air-launched, scramjet-powered hypersonic cruise missiles, which were funded by DARPA.
[138][139] In March 2024 Stratolaunch Roc launched TA-1, a vehicle which is nearing Mach 5 at 10.67 km (6.63 mi) in a powered flight, a risk-reduction exercise for TA-2.
[146][147] In 2021-2023, Heidi Shyu, the Under Secretary of Defense for Research and Engineering (USD(R&E)) is pursuing a program of annual rapid joint experiments,[148] including hypersonics capabilities, to bring down their cost of development.
[126] 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.
- The satellites of the NDSA, in gray, are to be deployed in constellations orbiting Earth, and constantly keep Earth in their view, depicted by the blue cones representing the fields of view of the satellite constellations. The satellites are to intercommunicate and serve the defensive systems arrayed against enemy hypersonic vehicles, and build a kill chain against them.
- Conversely, the same satellites can be used to track friendly hypersonic weapons and perform battle damage assessment of their strikes against targets. See JADC2 ( Joint all-domain command and control )
