When Concorde entered service 40 years ago, it more than doubled the speed of air travel at a stroke. Following Concorde’s retirement, airliners today fly once more at subsonic speeds, but engineers worldwide are looking to a future in which high-speed flight is an everyday occurrence. Except they want to go one better: not at supersonic, but hypersonic speeds.
Aerospace giant Airbus was last year awarded a patent that details how a future hypersonic aircraft, with delta wings reminiscent of Concorde, could travel at Mach 4.5—fast enough to carry passengers between Paris and Tokyo in just three hours.
But inevitably, technology that has reached the commercial realm will already have been investigated by the military. The United States, Russia, and China have all carried out test flights of hypersonic vehicles—those which travel at around five times the speed of sound—with varying degrees of success. Each also has plans for weapons systems that could be developed from them.
Because while these are often referred to as “fighter jets,” in truth the machines are more similar to missiles. Without pilots, they sit atop rockets which boost them to high supersonic speeds (Mach 4 and above), at which point they start up their own engines (if equipped) and accelerate to even faster cruise speeds—but not for long, as they usually run out of fuel quickly, and most of their flight time is spent in a glide, albeit an extremely fast one.
Current missiles have operated in this fashion for decades. Intercontinental ballistic missiles (ICBM) and some shorter-range versions use the same sort of flight path, with the missile formed of multiple rocket stages to provide enough power to arc high into the atmosphere, only flying faster and higher. The now retired U.S. AIM-54 Phoenix air-to-air missile had a top speed of Mach 5. What makes the current generation of hypersonic aircraft designs different is their capability to maneuver, making them harder to intercept.
