X-15 Flight 91 - All About All

X-15 Flight 91

Crew

• Joseph A. Walker

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

Unofficial world altitude record from 1963 to 2004. On this flight, Joe Walker became the first person to enter space twice. Maximum Speed - 6106 km/h. Maximum Altitude - 107,960 m. Second and final X-15 flight over 100 km. Unofficial altitude record set for class. Highest altitude achieved by X-15. 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.

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

Pilot Robert White commented on his high altitude X-15 flights, "My flights to 217,000 feet [66 km] and 314,750 feet [96 km] were very dramatic in revealing the earth's curvature ... at my highest altitude I could turn my head through a 180º arc and wow! - the earth is really round. At my peak altitude I was roughly over the Arizona/California border in the area of Las Vegas, and this was how I described it: looking to my left I felt I could spit into the Gulf of California. Looking to my right I felt I could toss a dime into San Francisco Bay."

Reference

• X-15 The NASA Mission Reports - by Robert Godwin - ISBN 1896522-65-3

NASA reports (PDF format)

• Hypersonics Before the Shuttle: A Concise History of the X-15 Research Airplane (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20000068530_2000075022.pdf)
• X-15 research results with a selected bibliography (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19650010561_1965010561.pdf)
• Flight experience with shock impingement and interference heating on the X-15-2 research airplane 1968 (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19920075739_1992075739.pdf)
• Thermal protection system X-15A-2 Design report 1968 (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19680016245_1968016245.pdf)