In a series of experiments, Chinese scientists have shown engine performance for hypersonic aircraft for which ethylene vapours are identified as fuel in a mixture of coal powder. At the start of an engine, the exhaust from an engine is similar to the smoke from a steam pipe, but in general, this fuel will be 20% more efficient and cleaner than alternative mixtures.
For the first time, Russian scientists proposed the use of coal powder for rocket-fired "explosive" engines about a decade ago. However, RON specialists recommended the use of liquid hydrogen as the basis for fuel. But liquid hydrogen is a complex system of on-board storage and transportation of fuel cooled to super-low temperatures, so the Chinese moved on to ethylene, more specifically its vapours, which are also suitable for fuel ignition and a continuous series of detonations.
In the physics experiments of Nanjing University of Science and Technology, it has been shown that the velocity of the shock wave in the engine on coal powder and ethylene vapours is 2,000 m/s, which is six times the speed of sound. What is important is that researchers have run a prototype engine at a wide range of temperatures in conditions of lack and excess oxygen. In all cases, the prototype has shown a steady start and detonation series. This means that this type of engine and fuel mixture will be suitable for flight at different speeds and altitudes. For example, a hypersonic aircraft with such an engine will be able to take off and land at normal airfields at low speeds, which is impossible or difficult to implement for other types of hypersonic engines.