China has announced it is building the world’s fastest wind tunnel to develop a new generation of super-fast airplanes, but it could also be used for hypersonic missile technology. Wind tunnels test how air will pass over a solid object, helping designers improve aerodynamics or reduce stress points for objects as they reach high speeds. State-run Xinhua news agency ran a report late Monday revealing the development of what it said would be the world’s fastest hypersonic wind tunnel. The 265-meter-long tunnel can be used to test hypersonic aircraft that can travel at speeds of up to Mach 25 (30,625 kph), 25 times the speed of sound, Han Guilai, a researcher with China’s State Key Laboratory of High Temperature Gas Dynamics at the Chinese Academy of Sciences, was quoted as saying.