The Bell X-1 and Breaking the Sound Barrier

The Bell X-1 and Breaking the Sound Barrier Bell X-1E Specifications: General Length: 31 ft. Wingspan: 22 ft. 10 in. Height: 10 ft. 10 in. Wing Area: 115 sq. ft. Empty Weight: 6,850 lbs. Loaded Weight: 14,750 lbs. Crew: 1 Performance Power Plant: 1 Ãâ€" Reaction Motors RMI LR-8-RM-5 rocket, 6,000 lbf Range: 4 minutes, 45 seconds Max Speed: 1,450 mph Ceiling: 90,000 ft. Bell X-1 Design Development: Development of the Bell X-1 began in the waning days of World War II as the interest in transonic flight increased. Initially contacted by the US Army Air Force and the National Advisory Committee for Aeronautics (NACA - now NASA) on March 16, 1945, Bell Aircraft began designing an experimental aircraft dubbed the XS-1 (Experimental, Supersonic). In seeking inspiration for their new aircraft, the engineers at Bell elected use a shape similar to a Browning .50-caliber bullet. This was done as it was known that this round was stable in supersonic flight. Pressing forward, they added short, highly-reinforced wings as well as a movable horizontal tailplane. This latter feature was included to give the pilot increased control at high speeds and later became a standard feature on American aircraft capable of transonic speeds. In the interest of retaining the sleek, bullet shape, Bells designers elected to use a sloped windscreen in lieu of a more traditional canopy. As a result, the pilot entered and exited the aircraft through a hatch in the side. To power the aircraft, Bell selected an XLR-11 rocket engine capable of around 4-5 minutes of powered flight. Bell X-1 Program: Never intended for production, Bell constructed three X-1s for the USAAF and NACA. The first began glide flights over Pinecastle Army Airfield on January 25, 1946. Flown by Bells chief test pilot, Jack Woolams, the aircraft made nine glide flights before being returned to Bell for modifications. Following Woolams death during practice for the National Air Races, the X-1 moved to Muroc Army Air Field (Edwards Air Force Base) to begin powered test flights. As the X-1 was not capable of taking off on its own, it was carried aloft by a modified B-29 Superfortress. With Bell test pilot Chalmers Slick Goodlin at the controls, the X-1 made 26 flights between September 1946 and June 1947. During these tests, Bell took a very conservative approach, only increasing speed by 0.02 Mach per flight. Dismayed by Bells slow progress towards breaking the sound barrier, the USAAF took over the program on June 24, 1947, after Goodlin demanded a $150,000 bonus for achieving Mach 1 and hazard pay for every second spent over 0.85 Mach. Removing Goodlin, the Army Air Force Flight Test Division assigned Captain Charles Chuck Yeager to the project. Familiarizing himself with the aircraft Yeager made several test flights in the X-1 and steadily pushed the aircraft towards the sound barrier. On October 14, 1947, less than a month after the US Air Force became a separate service, Yeager broke the sound barrier while flying X-1-1 (serial #46-062). Dubbing his plane Glamorous Glennis in honor of his wife, Yeager achieved a speed of Mach 1.06 (807.2 mph) at 43,000 feet. A publicity boon for the new service, Yeager, Larry Bell (Bell Aircraft), and John Stack (NACA) were awarded with the 1947 Collier Trophy by the National Aeronautics Association. Yeager continued with the program and made 28 more flights in Glamorous Glennis. The most notable of these was on March 26, 1948, when he reached a speed of Mach 1.45 (957 mph). With the success of the X-1 program, the USAF worked with Bell to build modified versions of the aircraft. The first of these, the X-1A, was intended to test aerodynamic phenomena at speeds above Mach 2. First flying in 1953, Yeager piloted one to a new record speed of Mach 2.44 (1,620 mph) on December 12 of that year. This flight broke the mark (Mach 2.005) set by Scott Crossfield in the Douglas Skyrocket on November 20. In 1954, the X-1B began flight testing. Similar to the X-1A, the B variant possessed a modified wing and was used for high speed testing until it was turned over to NACA. In this new role, it was used until 1958. Among the technology tested on the X-1B was a directional rocket system that was later incorporated into the X-15. Designs were created for the X-1C and X-1D, however the former was never built and the latter, meant for use in heat transfer research, only made one flight. The first radical change to the X-1 design came with the creation of the X-1E. Constructed from one of the original X-1s, the X-1E featured a knife-edge windscreen, new fuel system, a re-profiled wing, and enhanced data collection equipment. First flying in 1955, with USAF test pilot Joe Walker at the controls, the aircraft flew until 1958. During its final five flights it was piloted by NACA research pilot John B. McKay who was attempting to break Mach 3. The grounding of the X-1E in November 1958, brought the X-1 program to a close. In its thirteen-year history, the X-1 program developed the procedures that would be used in subsequent X-craft projects as well as the new US space program. Selected Sources NASA: Bell X-1 National Air Space Museum: Bell X-1