Credit: NASA. 63,541 bytes. 596 x 368 pixels.
The X-1A, B, and D were essentially identical rocketplanes intended to reach speeds above Mach 2. The X-1A and X-1D were destroyed in in-flight explosions; the X-1B survived, training future moon lander Neil Armstrong on its last flights in 1958.
Bell flight 1. Pilot familiarization. Fuel jettison test. Glide flight only.
Bell flight 3. First powered flight. False fire warning.
Bell flight 4. Plane demonstrated successful 4-cylinder engine operation.
Bell flight 5. Pilot noted low-frequency elevator buzz at mach 0.93, did not proceed above this speed, pending buzz investigation.
Bell flight 6. Buzz again noted at mach 0.93. Turbopump overspeeding caused pilot to terminate power and jettison remaining fuel.
AF flight 1. Reached mach 1.15. Familiarization purposes.
AF flight 2. Mach 1.5.
AF flight 3. First high-mach flight attempt by X-1A. Mach 1.9 attained at 18300 m during slight climb.
AF flight 4. Plane attained mach 2.44, but met violent instability above mach 2.3. Tumbled 15250 m, wound up in subsonic inverted spin. Yeager recovered to upright spin, then normal flight at 7625 m.
AF flight 5. Date estimated.
AF flight 6. Date estimated.
AF flight 7. Date estimated.
AF flight 8. Date estimated.
AF flight 9. Date estimated.
AF flight 10. X-1A attained 26564 m, un-official world altitude record for manned aircraft.
AF flight 11. X-1A reached 27374 m. Encountered same instability Yeager had, but at mach 1.97. Murray recovered after tumbling 6100 m down to 20130 m.
AF flight 12. Date estimated.
AF flight 13. Date estimated.
AF flight 14. Date estimated.
AF flight 15. Date estimated.
AF flight 16. Date estimated.
AF flight 17. Date estimated.
AF flight 18. Murray attained 27584 m. Air Force then turned X-1A over to NACA.
NACA flight 1. Familiarization. Walker attained mach 1.45 at 13725 m. Noted severe aileron buzz at mach 0.90 to 0.92.
Planned at NACA flight 2. Shortly before launch from B-29, X-1A suffered low-order explosion, later traced to detonation of Ulmer leather gaskets. Walker exited into B-29 bomb bay.