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X-15 Flight 91

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Title: X-15 Flight 91  
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Subject: X-15 Flight 90, X-15 program, List of X-15 flights, List of human spaceflights, List of space travelers by nationality
Collection: 1963 in Spaceflight, Suborbital Human Spaceflights, X-15 Program
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X-15 Flight 91

Flight 91
Mission type Test flight
Operator US Air Force/NASA
Mission duration 11 minutes, 8.6 seconds
Distance travelled 543.4 kilometers (337.7 mi)
Apogee 107.96 kilometers (67.08 mi)
Spacecraft properties
Spacecraft X-15
Manufacturer North American
Launch mass 15,195 kilograms (33,499 lb)
Landing mass 6,260 kilograms (13,800 lb)
Dry mass 6,577 kilograms (14,500 lb)
Crew size 1
Members Joseph A. Walker
Start of mission
Launch date August 22, 1963, 18:05:57 (1963-08-22T18:05:57Z) UTC
Launch site NB-52A #52-003, Edwards
Dropped over Smith Ranch Dry Lake
End of mission
Landing date Did not recognize date. Try slightly modifying the date in the first parameter. UTC
Landing site Rogers Dry Lake, Edwards

Joe Walker

X-15 Flight 91 was a 1963 American human spaceflight mission, and the second and final flight in the program to achieve sub-orbital spaceflight—a flight over 100 km in altitude—which was previously achieved during Flight 90 a month earlier. It was the highest flight of the X-15 program. It was the first flight of a reused spacecraft, as plane number three flew the previous sub-orbital flight on July 19. This mission was piloted by Joseph A. Walker on August 22, 1963, with the air-launch occurring from a modified Boeing B-52 Stratofortress support plane over Smith Ranch Dry Lake, Nevada, United States. Walker piloted the X-15 to an altitude of 107.96 km and remained weightless for approximately five minutes. The altitude was the highest manned flight by a spaceplane to that time and remained the record until the 1981 flight of Space Shuttle Columbia. Walker landed the X-15 about 12 minutes after it was launched, at Rogers Dry Lake, Edwards Airforce Base, in California. This was Walker's final X-15 flight.


  • Crew 1
  • Mission parameters 2
  • Mission highlights 3
  • Notes 4
  • References 5


Position Astronaut
Pilot Joseph A. Walker
Second spaceflight

Mission parameters

  • Mass: 15,195 kg fueled; 6,577 kg burnout; 6,260 kg landed
  • Maximum Altitude: 107.96 km
  • Range: 543.4 km
  • Burn time: 85.8 seconds
  • Mach: 5.58
  • Launch vehicle: NB-52A Bomber #003

Mission highlights

On this flight, Joe Walker became the first person to enter space twice. He had a maximum speed of 3,794 MPH and a maximum altitude of 354,200 feet. Second and final X-15 flight over 67 miles.[1] Unofficial altitude record set for class. Highest altitude achieved by X-15.[1] Last flight for Walker in X-15 program. Number 1 left RCS nozzle froze up. First flight with altitude predictor instrument (needed calibration).

The mission was flown by X-15 #3, serial 56-6672 on its 22nd flight.[1]

Launched by: NB-52A #003, Pilots Bement & Lewis. Takeoff: 17:09 UTC. Landing: 18:56 UTC.

Chase pilots: Wood, Dana, Gordon and Rogers.

The X-15 engine burned about 85 seconds. Near the end of the burn, acceleration built up to about 4 G (39 m/s²). Weightlessness lasted for 3 to 5 minutes. Re-entry heating warmed the exterior of the X-15 to 650°C in places. During pull-up after re-entry, acceleration built up to 5 G (49 m/s²) for 20 seconds. The entire flight was about 12 minutes from launch to landing.


  1. ^ a b c Jenkins (2000), p. 119


  • Goodwin, Robert (2000). X-15: the NASA mission reports, incorporating files from the USAF. Burlington, Ontario: Apogee Books.  
  • Jenkins, Dennis R. (2000), Hypersonics Before the Shuttle: A Concise History of the X-15 Research Airplane, NASA Technical Reports, NASA,  
  • Price, A. B. (1968), Thermal protection system X-15A-2 Design Report, NASA Technical Reports, NASA,  
  • Stillwell, W. H. (1965), X-15 research results with a selected bibliography, NASA Technical Reports, NASA,  
  • Watts, Joe D. (1968), Flight experience with shock impingement and interference heating on the X-15-2 research airplane, NASA Technical Reports, NASA,  
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