Initially designated the XS-1, (the S, which stood for Supersonic, was dropped early in the program), the X-1 was the first aircraft given an “X” designation, and became the first aircraft to exceed the speed of sound in controlled level flight on 14 October 1947. Developed jointly by the USAF, Bell and NACA, the type reached Mach 1.015 at approximately 45,000 feet in the hands of Captain ‘Chuch’ Yeager. The type was planned specifically for investigation into transonic and supersonic flight, and was based on a cylinderical fuselage that accommodated the 6000 lb (2722kg) thrust Reaction Motors E6000-C4 rocket motor and the tanks for its liquid propellants. The flying surfaces were straight but thin, and the first X-1 air-launch of the X-1 was made on 19 January 1946, but powered flights were not attempted until 9 December 1946 after an air drop from a Boeing B-29 motherplane, using the second prototype. The third was destroyed at Edwards AFB during flight fuelling operations.
Supersonic flight was achieved by Captain Charles 'Chuck' Yeager on 14 October 1947. The speed reached by the X-1 on that occasion was 670 mph (1,078 kph) at a height of 42,000 ft (12,800 m), and therefore equivalent to a Mach number of 1.015.
The three X-ls were followed by the second generation X-1s were designed to double the speed of sound and set altitude records in excess of 90,000 feet. Only the X-1A and X-1B were actually built, the X-1C, which was designed to test high-speed armaments, was cancelled before completion.
The X-1A had a longer fuselage for greater fuel capacity, a revised cockpit canopy, and turbopumps replacing the previously pressurised nitrogen fuel system: the X-1A reached a speed of Mach 2.435 and an altitude of more than 90,000 ft (27430m) on 4 June 1954.
In 1955 this aircraft was given new wing panels, but was destroyed before its first flight in this configuration. The X-1A was destroyed after it was jettisoned following an inflight explosion over Edwards AFB on 8 August 1955.
The X-1B was used for thermal research, and the X-1D was destroyed during what was to be its first powered flight in August 1951 after being jettisoned from its B-50 carrier-plane, following an explosion.
Despite the loss of the third X-1 and the X-1D, a requirement still existed for a higher performance X-1 so that the NACA could continue high-speed research. To satisfy this requirement, the second X-1 was almost completely rebuilt and redesignated the X-1E. Significant modifications included an updated knife-edge windscreen canopy, ultra-thin wings (4 percent thickness/chord ratio), turbo-driven fuel pumps, and a rocket assisted ejection seat.
With these aircraft, a speed of 1,650 mph (2655 km/h) at 70,000 ft (21,325 m) and altitudes of up to 90,000 ft (27,425 m) were attained in 1953-54.
The maximum altitude achieved by the X-1E was over 75,000 feet, and the top speed was Mach 2.24 (1,450 mph). During its test series, the X-1E demonstrated that the thin wing section was technically feasible for use on supersonic aircraft. An improved Reaction Motors XLR11, using a low-pressure turbopump, was also validated during X-1E test flights.
The aircraft was retired from service in November 1956 after 26 flights, and is now on permanent display in front of the NASA Dryden Flight Research Center.
The first X-1 is on permanent display in the National Air and Space Museum in Washington, DC. The third X-1 was destroyed on 9 November 1951 at Edwards AFB, California.
A total of 156 flights were made with the X-1, 21 with the X-1A, 27 with the X-1B, one with the X-1D and 26 with the X-1E.
Powered by: One Reaction Motors XLR-11-RM-5 four-chamber bi-fuel (alcohol and liquid oxygen) rocket, maximum of 6,000 lb (2722 kg) st for 2.5 min.
Wing span: 28 ft 0 in (8.53 m).
Length: 31 ft 0 in (9.45m).
Height: 10 ft 8 in (3.25m).
Empty Weight: 8,100lbs (3,674kg)
Gross wt: 13400 lb (6,078 kg).
Max speed: 1000 mph (l609 kph) at 60,000 ft (18,2 90 m).
Rate of climb: 28.000 ft (8,534 m)/min.
Ceiling: 22250 m / 73000 ft
Accommodation: Crew of 1.
Speed: 1650 mph.
Ceiling: 90,000 ft.
Power: 6,000 lb thrust Reaction Motors XLR-11-RMS rocket
Full power endurance: 4.2 minutes
Span: 28 ft
Weight: 16,000 lb