Mach 30 wind tunnel to ‘put China decades’ ahead in hypersonic race

A Chinese physicist has said that a new wind tunnel in Beijing to be unveiled “soon” will put China decades ahead of the rest of the world in hypersonic technology.

Chinese Academy of Sciences researcher Han Guilai told an online lecture last week that the JF-22 wind tunnel, in Beijing’s Huairou district, was capable of simulating flights at up to 10km per second – 30 times the speed of sound. Together with an existing facility, also in Beijing, it would put China “about 20 to 30 years ahead” of the West.

Han, from China’s top hypersonic research agency the Institute of Mechanics, said the surface of an aeroplane travelling at such a speed could reach 10,000 degrees Celsius (18,032 Fahrenheit) – hot enough to break air molecules into atoms, even giving some of them an electric charge.

“This air is no longer the air we breathe in,” said Han. “The flying vehicle we study is like swimming in mud.”

Han said the power produced by the JF-22 wind tunnel would reach 15 gigawatts – nearly 70 per cent of the installed capacity of the world’s largest hydropower station Three Gorges Dam in China’s southwestern Sichuan province, or more than seven times the Hoover Dam in Nevada.

China, along with other major countries, has made huge investments in the development of hypersonic flight technology, which could make it possible for air travellers to land anywhere in the world in one or two hours. It would also cut the cost of space launches by more than 90 per cent, potentially bringing space travel within popular reach.

As China and the US compete for global technology leadership, the race to bring hypersonic flight to life has intensified.

Aerion, a private company developing hypersonic passenger aircraft based in Nevada, folded this month due to financial and technical hurdles. Last month, a much anticipated hypersonic weapon test by the US Air Force ended in failure.

Hypervelocity experiments started in the West in the late 1940s, and US pilot William John Knight briefly reached Mach 6.7 in a rocket-powered X-15 test plane in the 1960s. Despite their early start, Western countries so far lack a combat-ready hypersonic weapon, while none of their missile defence systems could intercept such high-speed objects from China or Russia.

China has already deployed numerous types of hypersonic weapons in recent years, with the number of test flights conducted in one year equivalent to a decade of tests in the US.

Chinese hypersonic test flights have recorded unusually high success rates, with no reported crashes. In 2019, Chinese space authorities conducted a secret experiment of what is believed to be a prototype space plane that can take off or land at an ordinary airport. Researchers have also revealed details, in domestic scientific journals, of hypersonic engine designs unseen anywhere else in the world.

Part of China’s success in hypersonics is because of the unique technology used in its wind tunnels. Unlike facilities in other countries – which use mechanical compressors to generate high-speed air flow – the JF-22 uses chemical explosions.

When the tunnel fires up, its fuel burns at a speed 100 million times faster than a gas stove, generating shock waves similar to those encountered by air planes at hypervelocity in high altitudes. According to Han, each plane or weapon model “needs to take about 10,000 tests in the tunnel” before production.

LENS II, the most advanced wind tunnel in the US, has simulated flights up to Mach 7, with the simulation lasting 30 milliseconds. In contrast, the JF-22’s average runtime could reach 130 milliseconds, with a much higher top speed, Han said.

“Our experiment time is much longer than theirs, so the aircraft model can be larger than theirs, and the experiments can be more advanced than theirs. This determines our leading position in the world.”

Qian Xuesen, father of China’s rocket programme, coined the term “hypersonic” in a 1946 paper after he discovered that the behaviour of air flow followed completely different rules at five times faster than sound.

Qian “dug a big hole at the time, and now people from all over the world are jumping into the hole,” said Han, a fourth-generation researcher with the hypersonic research programme started by Qian 60 years ago.

Han could not be immediately reached for comment on Monday but a Shanghai-based hypersonic physicist, who asked not to be named because of the project’s sensitivity, confirmed the information in the lecture.

While the launch date of the JF-22 remains classified, it will work together with the JF-12, an older tunnel with about a fifth of the power output, to simulate flight conditions at both higher and lower altitudes where air densities were quite different, according to the researcher.

“There is a Chinese saying, it takes 10 years to sharpen a sword,” Han said. “We have spent 60 years sharpening two swords. And they are the best.”

Via https://www.scmp.com/news/china/science/article/3135491/mach-30-wind-tunnel-put-china-decades-ahead-hypersonic-race