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 the technology of the National Aerospace Plane.
The goal of the Hyper-X project was to flight test the key powerplants and related technologies for hypersonic aircraft. The first two X-43 test machines were made to fly at Mach 7, which was faster than any jet aircraft had ever flown; while the third X-43 was able to develop a speed of Mach 9.6.
To put that in perspective, the highest speed achieved by NASA’s X-15 rocket plane was Mach 6.7 during flight tests in the late 1960s.
The X-43A was a 12-foot (3.7 m) unmanned test vehicle. It featured a lift-body design in which the airframe provided significant lift for flight rather than relying on the wings. The plane weighed approximately 1,400 kg.
In addition, the test aircraft was designed to be fully controllable in high-speed flight even when gliding without an engine. However, the aircraft was not intended for landing and recovery, instead the test machines were dropped in the Pacific Ocean after the test flight was completed.
The first test, which took place on June 2, 2001, failed after the Pegasus launch vehicle lost control just 13 seconds after liftoff 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 November 16, 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 multi-mode engine. The X-43B engine was supposed to operate as a conventional turbojet engine at low altitudes and switch to GPPRD mode at high altitudes and speeds.
The planned flights of the X-43B were to take place in 2009, following the completion of testing of another Hyper-X machine, the X-43C, which was to demonstrate the operation of a solid hydrocarbon-fueled GPP at speeds between Mach 5 and 7.
But the flights were canceled in March 2004 due to a change in NASA’s strategic goals following the announcement of the “Presidential Vision for Space Exploration” in January of that year. Although funding for the X-43C continued in NASA’s 2005 budget, the program was soon terminated.
Tests of the hypersonic aircraft were continued as part of the X-51 program, which began in 2005, and the aircraft made its first flight in 2010.