China has developed an engine capable of reaching Mach 9 with aviation fuel

Hypersonic speeds have for several years been a priority area of ​​research for all of the world's major armies. The announcement, in 2017, of the entry into service of the Russian hypersonic airborne missile Kinzhal, and a few months later, of the hypersonic glider Avangard, had the effect of an electric shock in the West as in the world, whileno existing anti-missile system was then capable of opposing vectors moving at such speeds and capable of maneuvers. Since then, we have witnessed an explosion in terms of the program, the United States, the Europeans, the Chinese and the Indians having all announced significant advances in this area. Several hypersonic systems are already in service, such as the Kinzhal and Tzirkon Russian, or Chinese DF-17, while the American systems are due to enter service from 2024.

To achieve these speeds above Mach 5 and maintain maneuvering capabilities, the very definition of a hypersonic weapon, two propulsion technologies are used. The first, and the most classic, relies on a high-powered rocket engine and a ballistic or semi-ballistic trajectory, as for the Russian Kinzhal derived from the Iskander-M short-range ballistic missile, or China's new YJ-21 airborne missile presented for the first time at the last Zhuhai show. The second alternative is based on the use of an aerobic engine, ie using atmospheric air as combustion. Unfortunately, a traditional engine is unable to operate above a speed approaching Mach 3, because the speed of the airflow within it must remain subsonic to control the combustion of the fuel. An alternative emerged through the Scramjet, a turbojet capable of slowing and cooling atmospheric air and controlling combustion at supersonic speeds but below Mach 2, allowing it to operate at speeds exceeding Mach 5.

The Scramjet, or superstatoreactor, is used today by the Russian hypersonic anti-ship missile Tzirkon, and several countries are actively working to develop this technology to equip their cruise missiles with it. But another technology emerged about ten years ago, to meet the hypersonic challenge, that of oblique detonation engines, which replace the classic combustion of the air-fuel mixture, by a succession of detonations of this same mixture, generating a considerably higher energy release, while being less sensitive to the speed of the air, allowing to reach, theoretically, significantly higher speeds than the Scramjet, with an energy performance, therefore an autonomy, much higher. This approach is not, strictly speaking, new, the first device equipped with a pulsed detonation wave engine having demonstrated its effectiveness in 2008. However, the announcement made by the Chinese Academy of Sciences, according to which such an engine, powered by aviation fuel, would have been successfully tested in the hypersonic tunnel JF-12 in Beijing, deserves special attention, especially since Chinese engineers announce that the engine would be able to reach a speed of Mach 9.

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