A group of Chinese scientists claims to have found a method to significantly cut the cost of commercial hypersonic travel.
First picked up by the South China Morning Post, researchers claim an air-breathing engine, fuelled by a mixture of ethylene and ultra-fine coal powder, can create explosive shock waves that travel six times faster than the sound barrier.
Led by Weng Chunsheng, a professor at the Nanjing University of Science and Technology, the team fabricated an experimental device to put the hypothesis through its first practical steps.
Nanjing University’s website describes Weng’s goal as an attempt to develop an efficient hypersonic engine capable of achieving Mach 7 (8 643 kilometres per hour) at near-space altitudes over long periods.
It should also complete low-speed, low-altitude actions like taking-off and landing well, Weng added.
The early prototype creates thrust by blowing bacteria-sized coal particles into an ignition chamber filled with oxygen. The highly-combustible mix is then lit by ethylene propellent and an electric spark.
The engine creates these supersonic explosions remarkably efficiently. If the initial shock is powerful enough, the wave of compressed air around the explosion sets off a chain reaction of similar blasts, the researchers explained.
Finding a means to control the often unpredictable ignition phase presented the research team with one of its most significant obstacles. Weng found a solution from an unusual source: ethylene.
The sweet-smelling organic chemical is used as a ripening agent for a great many fruit and vegetable varieties, as well as in the production process of alcohol, plastics and textiles.
Ethylene is also highly combustible, more so than ultra-fine coal in an oxygen suspension. The team immediately noticed the coal-ethylene mixture created powerful detonations and did so consistently.
Weng’s report also indicated that the engine performed better than expected in less than ideal conditions, including instances where oxygen levels at ignition were too high or low.
Hypersonic technology research and development is invested in fiercely by the globe’s players as it has the potential to revolutionise both the transport and military industries.
Coal-assisted hypersonic travel was proved plausible more than a decade ago when the Russian Academy of Sciences demonstrated the principle with a coal-hydrogen fuel mixture.
Hydrogen, like ethylene, is combustible but needs to be kept at extremely low temperatures to remain in a liquid state.
Since then, China, India and the US have all dedicated resources to the field in an effort to get ahead of their competitors.
Rocket scientists, backed by an ambitious and innovative Chinese National Space Administration, have experimented with other hypersonic fuel sources including boron.
The fifth element on the periodic table, boron is a volatile substance that reacts powerfully when exposed to water or air, giving off heat in the process. It is considered an ideal candidate for solid-fuel rockets and even torpedoes.