Technical analysis of hypersonic aircraft, advanced engines and strategic consequences for air combat and tomorrow’s fighter aircraft.

Hypersonic technologies are changing the balance in military aeronautics. Supersonic speed, long an operational limit, is becoming secondary to aircraft capable of speeds in excess of Mach 5. Projects for hypersonic jets and adapted engines are multiplying, from the United States to China, with a clear objective: to guarantee air superiority through speed, altitude and thermal stealth. These developments don’t belong to a hypothetical future, but to a transformation that has already begun, with active tests and flying prototypes. This article describes the technical, industrial and strategic aspects of hypersonic aircraft. It analyzes their implications for air combat, doctrines of engagement and logistics chains.

The development of hypersonic jets: technological status and industrial players

Hypersonic jets are aircraft capable of speeds in excess of Mach 5 (over 6,174 km/h). This speed radically alters fighter aircraft design and associated constraints. At these speeds, thermal resistance and dynamic pressure call for the use of specific materials and aerodynamics integrated into the engine itself.

Several countries are investing heavily in this field. The American “Mayhem” program, led by the US Air Force Research Laboratory, is aimed at a modular, multi-mission hypersonic demonstrator. Lockheed Martin is working on the SR-72, nicknamed the “Son of Blackbird”, designed to reach Mach 6, while DARPA is leading the HTV-3X and Falcon programs. In China, Beihang University is collaborating with AVIC on operational prototypes by 2030. Russia is testing the MiG-41 (PAK DP), designed to reach Mach 4.3 with a cruising altitude of over 30,000 meters.

One of the technical obstacles remains the engine. Conventional turbojet engines become inefficient at Mach 3 and above. Scramjets (supersonic combustion ramjets) are the answer: they use ambient air as a combustive agent, with supersonic combustion. NASA’s X-43A, equipped with a scramjet, reached Mach 9.6 (11,854 km/h) in 2004.

The cost remains high: each test flight of the X-51 Waverider cost around €65 million. Development of the SR-72 is estimated at over 1.8 billion euros. The return on investment is assessed less in terms of financial profitability than in terms of tactical superiority.

The overall design was also rethought: no conventional air intake, lines integrated into the engine, active thermal protection, digital flight controls. Supersonic speed becomes an outdated standard.

Strategic implications for future air combat

The transition to hypersonic speeds is transforming the air combat environment. The first impact is on reaction time. A hypersonic jet covers 1,000 kilometers in less than 10 minutes. The interception window is reduced to a few tens of seconds, rendering current warning systems ineffective.

Engagement doctrines will have to be reviewed. Anticipation takes precedence over reaction. The USAF is considering the use of hypersonic fighter escorts for deep strikes even before defenses are saturated. The very notion of air superiority is changing: speed becomes the dominant tactical element, ahead of maneuverability.

Dogfighting loses relevance. At Mach 6, a turn requires a radius of several kilometers, making visual confrontation obsolete. Combat is played out at long range, with weapons that are also hypersonic. Raytheon’s HAWC missile reaches Mach 7. The Russian 3M22 Zircon missile exceeds Mach 8 (9,878 km/h).

Thermal impact becomes an operational criterion. At Mach 6, the external temperature exceeds 1,000°C. Infrared radiation is intense. Radar stealth must therefore be accompanied by thermal stealth. IRST (Infrared Search and Track) sensors will be revised to incorporate this data.

Logistics chains will be tightened. A scramjet engine cannot be replaced on the runway like a turbojet engine. In-flight refueling becomes virtually impossible at these speeds. The range will have to incorporate hybrid flight profiles, with final acceleration only in hostile zones.

Human piloting becomes a limiting factor. At Mach 7, the g-load in maneuvers exceeds 10 g, making manned flight uncertain. Future hypersonic jets will probably be autonomous or teleoperated.

Last but not least, countries with an aeronautical industrial base that masters these aircraft will have a direct strategic advantage. This will not just be an evolution in aviation, but a redefinition of the theater of operations.

Industrial, technological and geopolitical challenges

The development of hypersonic jets is not a one-off innovation, but a structural change in military aviation. The United States, China, Russia, India and the European Union are conducting simultaneous programs. The global budget for hypersonic projects will exceed €20 billion by 2024.

The industry is reorganizing. Rolls-Royce, Safran, General Electric, NPO Saturn, IHI and Reaction Engines are developing hybrid engines capable of mixed-cycle operation: turbojet up to Mach 3, scramjet beyond. Reaction Engines is developing SABRE (Synergetic Air Breathing Rocket Engine), designed to go from zero to Mach 5.5 without a break in propulsion.

The materials supply chain follows: refractory alloys, ultra-high-temperature ceramics, carbon-carbon composites. Inconel 718 alloy is used in the X-51. Hafnium carbide, tested by Chinese laboratories, withstands temperatures of 3,900°C. These materials are rare, expensive and strategically sensitive.

In geopolitical terms, hypersonic proliferation is becoming a lever of deterrence. France is lagging behind, despite ONERA-Safran research. India, via BrahMos-II, is aiming for Mach 7. Germany is studying hypersonic ISR (Intelligence, Surveillance, Reconnaissance) drones. Israel is cooperating with MIT on mini-scramjets adapted to UAVs.

Missile defense is also concerned. No ground-based system can effectively intercept a supersonic Mach 8 missile or aircraft on an unpredictable trajectory. Radar must detect, track, target and fire in less than 30 seconds, which exceeds the current capabilities of the Patriot PAC-3, the S-400 or the Aster-30.

Doctrine is also changing for ISR missions. A hypersonic aircraft can penetrate a territory, collect data, and leave before the defense reacts. Satellites become slow, vulnerable and dependent on fixed orbits.

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