This article is about the experimental aircraft. For the Irish band, see Bell X1 (band)
The Bell X-1, originally designated XS-1, was a joint NACA-U.S. Army Air Forces-U.S. Air Force supersonic research project built by the Bell Aircraft Company. Conceived in 1944 and designed and built during 1945, it reached nearly 1,000 miles per hour (1,600 km/h; 870 kn) in 1948. A derivative of this same design, the Bell X-1A, having greater fuel capacity and hence longer rocket burning time, exceeded 1,600 miles per hour (2,600 km/h; 1,400 kn) in 1954. The X-1 was the first airplane to exceed the speed of sound in level flight and was the first of the so-called X-planes, a series of American experimental rocket planes designated for testing of new technologies and often kept secret.
Design and development
On 16 March 1945, the U.S. Army Air Forces Flight Test Division and the National Advisory Committee for Aeronautics (NACA) made a contract with the Bell Aircraft Company to build three XS-1 (for "Experimental, Supersonic", later X-1) aircraft to obtain flight data on conditions in the transonic speed range.
The X-1 was in principle a "bullet with wings", its shape closely resembling a Browning .50-caliber (12.7 mm) machine gun bullet, known to be stable in supersonic flight. The pattern shape was followed to the point of seating its pilot behind a sloped, framed window inside a confined cockpit in the nose, with no ejection seat. After the rocket plane ran into compressibility problems in 1947, it was modified with variable-incidence tailplane. An all-moving tail was tested in subsonic flight on the Curtiss XP-42 research vehicle in mid-1944, and earmarked for future high speed research, but its first successful transonic flight was on the X-1, allowing it to pass through the sound barrier safely.
The rocket propulsion system was a four-chamber engine built by Reaction Motors, Inc., one of the first companies to build liquid-propellant rocket engines in America. This rocket burned ethyl alcohol diluted with water with a liquid oxygen oxidizer. Its thrust could be changed in 1,500 lbf (6,700 N) increments by firing just one or more than one of its chambers. The fuel and oxygen tanks for the first two X-1 engines were pressurized with nitrogen gas, but the rest used steam-driven turbopumps. The all-important fuel turbopumps were necessary to raise the chamber pressure and thrust while making the engine lighter,
The Bell Aircraft chief test pilot, Jack Woolams, became the first man to fly the XS-1. He made a glide flight over Pinecastle Army Airfield, in Florida, on 25 January 1946. Woolams completed nine more glide flights over Pinecastle before March 1946, when the #1 rocket plane was returned to Bell Aircraft in Buffalo for modifications to prepare for the powered flight tests. These were held at the Muroc Army Air Field in Palmdale, California. Following Woolams' death on 30 August 1946, Chalmers "Slick" Goodlin was the primary Bell Aircraft test pilot for the X-1-1 (serial 46-062). He made 26 successful flights in both of the X-1 from September 1946 through June 1947.
The Army Air Forces was unhappy with the cautious pace of flight envelope expansion and Bell Aircraft's flight test contract for airplane #46-062 was terminated. The test program was taken over by the Army Air Force Flight Test Division on 24 June after months of negotiation. Goodlin had demanded a US$150,000 bonus for breaking the sound barrier. Flight tests of the X-1-2 (serial 46-063) would be conducted by NACA to provide design data for later production high-performance aircraft.
Mach 1 flight
in front of the X-1 that he christened the Glamorous Glennis
On 14 October 1947, just under a month after the U.S. Air Force had been created as a separate service, the tests reached their peak with the first manned supersonic flight, piloted by Air Force Captain Charles "Chuck" Yeager in aircraft #46-062 that he had christened the Glamorous Glennis for his wife. This rocket-powered airplane was drop launched from the bomb bay of a modified B-29 Superfortress bomber, and it glided to a landing on the dry lake bed. XS-1 flight number 50 is the first one in which the X-1 recorded supersonic flight, at Mach 1.06 (313 m/s, 1,126 km/h, 800 mph) peak speed.
As a result of the X-1's initial supersonic flight, the National Aeronautics Association voted its 1948 Collier Trophy to be shared by the three main participants in the program. Honored at the White House by President Harry S. Truman were Larry Bell for Bell Aircraft, Captain Yeager for piloting the flights, and John Stack for the contributions of the NACA.
The story of Yeager’s 14 October flight was leaked to a reporter from Aviation Week, and The Los Angeles Times featured the story as headline news in their 22 December issue. The magazine story was released 20 December. The Air Force threatened legal action against the journalists who revealed the story, but none was ever taken.
On 5 January 1949, Yeager used Aircraft #46-062 to carry out the only conventional (runway) take off performed during the X-1 program, reaching 23,000 ft (7,000 m) in 90 seconds.