The United States has long been a leader in the development of the fastest aircraft. NASA’s X-43 was developed as part of the Hyper-X program in the late 1990s. As part of the “better, faster, cheaper” program developed by the space agency, Hyper-X used National Aerospace Aircraft technology.

The purpose of the Hyper-X project was to flight-test core power plants and related technologies for hypersonic aircraft. The first two X-43 test machines were built to fly at Mach 7, faster than any jet has ever flown; the third X-43 managed to develop a speed of Mach 9.6.

To put that in perspective, the top speed NASA’s X-15 rocket plane reached during flight tests in the late 1960s was Mach 6.7.

The X-43A was a 12-foot (3.7 m) unmanned test vehicle and featured a lift fuselage design where the fuselage provided significant lift for flight rather than relying on the wings. The aircraft weighed about 1,400 kg.

In addition, the test aircraft was designed to be fully controllable in high-speed flight, even while gliding without an engine. But the aircraft was not designed for landing and recovery, instead the test machines were dropped into the Pacific Ocean after the test flight was completed.

The first test, conducted on June 2, 2001, failed when the Pegasus launch vehicle lost control just 13 seconds after takeoff from the B-52 launch vehicle. The second test in 2004 was successful and the aircraft accelerated to Mach 6.83 (7456 km/h). The third X-43A prototype took off on 16 November 2004 and set a speed record of Mach 9.64 (10,240.26 km/h) at an altitude of about 33,500 meters.

The X-43 program was originally intended to include two additional machines, the X-43B was to be used to demonstrate a multimode engine. The X-43B engine was supposed to operate like a conventional turbojet engine at low altitudes and switch to GPPRD mode at high altitudes and speeds.

The X-43B’s scheduled flights were to take place in 2009 following the completion of testing another Hyper-X machine, the X-43C, which will show a solid hydrocarbon-fueled GES operating at speeds between Mach 5. and 7.

However, in March 2004, flights were canceled due to changes in NASA’s strategic goals, following the announcement of the “Presidential Space Exploration Vision” in January of the same year. Although funding for the X-43C continued in NASA’s 2005 budget, the program was soon terminated.

Tests of the hypersonic aircraft continued within the scope of the X-51 program, which started in 2005, and the aircraft made its first flight in 2010.