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The Bell X-1 was an experimental rocket powered aircraft that was the first to breach the sound barrier in level flight.
The X-1 was produced in an attempt to solve some of the problems associated with supersonic flight. Work on the project began in 1944, and a draft specification for the aircraft was completed by December 1944. On 16 March 1945 Bell received a contract to produce three aircraft, known internally as the Bell Model 44 and officially as the XS-1 (eXperimental Supersonic), changed to the X-1 in 1947.
The fuselage of the X-1 was modelled on the shape of a 0.50 calibre bullet, which could travel faster than sound. It was a conventional stressed skin aircraft. The fuselage had a circular cross-section. The wings were straight, with a slightly swept back leading edge and no dihedral. Power was provided by a single four chamber Reaction Motors bi-fuel XLR-11-RM3 rocket engine which could provide 6,000lb static thrust at sea level for five minutes. The idea was that the X-1 would be carried into the air under a B-29 Superfortress to save on fuel.
The first X-1 was completed on 27 December 1945, apart from the engine. It made its first flight on 25 January 1946, when it was released from below a B-29 with Jack Woolams at the controls. This was the first of ten unpowered gliding flights between then and 6 March 1946. The X-1 was then withdrawn to have its wings modified, and didn't return to the programme until April 1947. By then Woolams had been killed in an accident while flying a racing P-39.
The second prototype made its first flight as a glider on 11 October 1945, with Chalmers Goodlin at the controls. This was followed by the first powered flight on 9 December 1946, where the X-1 reached Mach .75. The first aircraft joined the powered test programme on 11 April, reaching Mach .77. In May 1947 the two aircraft were turned over to the USAAF.
The two aircraft were used for different projects. Aircraft No.1 was used by the Air Force to investigate the transonic and supersonic speed envelope. No.2 was to be used by NACA to explore stability and control problems.
The Air Force selected three test pilots, the most famous of whom was Charles 'Chuck' Yeager. He made his first gliding flight in the X-1 on 6 August 1947 and his first powered flight on 29 August. Finally, on Tuesday 14 October Yeager took the aircraft to Mach 1.06, the first time a powered aircraft had breached the speed of sound in level flight. Yeager was able to raise the record to March 1.45 on 26 March 1948. X-1 no.1 made its last flight on 5 December 1950.
A third X-1 was delivered in April 1951, with a new steam-driven turbo-pump. This aircraft made its first glider flight on 20 July 1951, but was destroyed after an accidental explosion before its second flight.
A second version of the X-1 was also under development, as the Bell Model 58. This used the same wings, horizontal tail and rocket as the X-1, but with a new fuselage. This was 4ft 6in longer, carried more fuel and had a stepped windscreen. It was also the first to get an ejector seat. Four of these were ordered, but only three were completed, as the X-1A, X-1B and X-1D.
The X-1D was the first of the new aircraft to be completed. It had a low pressure fuel system and could carry more fuel. It made its first gliding flight on 24 July 1951, but it was lost after an explosion in August 1951.
The X-1A made its first gliding flight on 14 February 1953 and its first powered flight on 21 February. On 9 December Yeager took this aircraft to Mach 1.9 and on 12 December to Mach 2.4. In August 1954 it reached an altitude of 90,440ft. This aircraft was lost after an explosion in the summer of 1955.
The X-1B made its first gliding flight on 20 June 1954 and its first powered flight on 8 October 1954. This aircraft made seventeen flights for NACA before it was grounded by the discovery of cracks in the liquid oxygen tanks.
The second X-1 was later give a new even thinner wing, developed by Stanley Aviation, and became the X1-E. This aircraft made its first gliding flight on 3 December 1955, and then took place in at least 25 further flights, reaching March 2.24. This aircraft was grounded after its twenty sixth flight on 6 November 1958.
X-1
Engine: Reaction Motors bi-fuel XLR-11-RM3 rocket engine
Power: 6,000lb static thrust
Crew: 1
Span: 28ft 0in
Length: 30ft 11in
Height: 10ft 10in
Empty Weight: 7,000lb
Loaded Weight: 12,250lb
Maximum Speed: Mach 2.44/ 1,612mph
Ceiling: 70,000ft
Endurance: 5 minutes
X-1A/B/D
Engine: Reaction Motors bi-fuel XLR-11-RM3 rocket engine
Power: 6,000lb static thrust
Crew: 1
Span: 28ft 0in
Length: 35ft 8in
Height: 10ft 8in
Empty Weight: 6,880lb
Loaded Weight: 16,487lb
Maximum Speed: Mach 2.44/ 1,612mph
Ceiling: 90,000ft
Endurance: 4min 40sec