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Beginning in 1944, development of a rocket powered plane began.  The first was the Bell X-1 in 1946.   This is the plane Charles "Chuck" Yeager piloted to mach 1.06 on 14 October 1947, breaking the sound barrier for the first time.  Later planes were developed to fly higher and faster. (See The X-Planes for more information on the X-Plane programs and a X-Plane gallery.)

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Credit - Boeing Co.

The North American X-15 was the first plane which could actually be flown into space. By definition in the United States, pilot-astronaut wings are awarded to those who fly above 80 km/50 mi. By FAI definition, only flights above 100 km (Karman Line) qualify as astronaut flights. Only two flights, 90 and 91, meet FAI requirements. During the life of the X-15 program (199 flights between 8 June 1959 and 24 October 1968), 13 flights above 80 km earned 8 pilots their astronaut wings. Joseph H. Engle, who later went on to fly the Space Shuttle, made 3 of these flights. Following are the "astronaut" flights.

X-15-2 after crash landing (Credit: NASA)

The original X-15's were designated as X-15A's. When vehicle #2 was seriously damaged in a crash landing on 9 November 1962, it was rebuilt as an X-15A-2 with a stretched fuselage and drop tanks. This vehicle was also later covered with a white heat ablative coating. North American also proposed an X-15B (never built) which could have taken off vertically, flown a single orbit around the earth, then returned and been ditched in the ocean after the pilot had ejected. The vehicle would have then been lost.

X-15 Astronaut Flights
Flight # Date Start UTC End UTC Elapsed Altitude (m) Pilot Vehicle
62 17 July 1962 16:31:10 16:41:30.7 10 minutes, 10.7 seconds 95940 Robert M. White 3
77 17 January 1963 19:59:16 19:08:59.9 9 minutes, 43.9 seconds 82810 Joseph A. Walker^ 3
87 27 June 1963 16:56:03 17:06:31.1 10 minutes, 28.1 seconds 86870 Robert A. Rushworth 3
90 19 July 1963 17:19:53 17:31:17.9 11 minutes, 24.9 seconds 106010
Joseph A. Walker^ 3
91 22 August 1963 17:05:42 17:16:50.6 11 minutes, 8.6 seconds 107960
Joseph A. Walker^ 3
138 29 June 1965 17:21:18 17:31:50.3 10 minutes, 32.3 seconds 85527 Joseph H. Engle 3
143 10 August 1965 18:24:10 18:34:01.8 9 minutes, 51.8 seconds 82601 Joseph H. Engle 3
150 28 September 1965 17:08:06 17:20:02.8 11 minutes, 56.8 seconds 90099 John B. McKay^ 3
153 14 October 1965 19:45:57 19:55:14.7 9 minutes, 17.7 seconds 81230 Joseph H. Engle 1
174 1 November 1966 21:24:47 21:35:30.8 10 minutes, 43.8 seconds 93540 William H. Dana^ 3
190 17 October 1967 16:38:36 16:48:42.4 10 minutes, 6.4 seconds 85500 William J. Knight 3
   191 * 15 November 1967 18:30:07.4 18:34:57.5 4 minutes, 50.1 seconds 81080 Michael J. Adams 3
197 21 August 1968 16:04:48 16:14:11.3 9 minutes, 23.3 seconds 81530 William H. Dana^ 1

* Fatal accident, aircraft destroyed. After reaching peak altitude, entered spin at Mach 5. Entered dive at 30,000 m, began high frequency pitch oscillations, aircraft disintegrated when these reached 15 Gs.
^ Being NASA pilots and not Air Force pilots, these men were not awarded astronaut wings until 23 August 2005. Only Bill Dana was alive at the time to receive his wings.

X-15 Vital Statistics

Contractor: North American Aviation, Inc.
Number Built: 3
Powerplant: One Reaction Motors XLR99 Pioneer (throttleable between 25,000 to 50,000 lbs thrust). Prior to November 1960, two Reaction Motors XLR11-RM-5 rockets with 8,000 lbs thrust each were used.
Wingspan: 22 ft, 4 in
Length: 50 ft, 9 in (The X-15A-2 was 53 ft, 2 in)
Height: 12 ft, 7 in
Width: 7 ft, 4 in
Weight: 56,130 lbs gross
Cost: $300 million for design, development, and testing of 3 aircraft
Max Speed: Mach 6.70 (4,520 mph)
Ceiling: 324,200 ft (98,800 m)
Flight Controls: Two sets of guidance controls were used. Airplane flight controls were used while flying in the lower, thicker air. Thrusters were used for control at the edge of space.

The X-15 hull is made of Iconel X, a special steel alloy (steel and nickel) made by International Nickel Company. The hull is held together by stainless steel. Aluminum is also used internally where there are no heat or load problems.

The landing gear consists of two skids under the tail of the plane and a nose wheel.

The pilot wore a MC-2 full-pressure suit (shown in pictures at bottom of page). The ejection seat rocket could develop 6100 pounds of thrust for a split second and would propel the pilot up and to the rear. The seat had stabilizing fins for the drop to 15,000 feet where the pilot would be released. If the ejection altitude was below 15,000 feet, the pilot was released after 3 seconds. After release from the seat, the pilot would descend with a 25 foot circular parachute.

Because of the large fuel consumption, the X-15 was air launched from a modified B-52 aircraft at 45,000 feet and a speed of about 500 mph. Depending on the mission, the rocket engine provided thrust for the first 80 to 120 seconds of flight. The remainder of the normal 10 to 11 minute flight was powerless and ended with a 200 mph glide landing.


(click to enlarge)
  NB-52A Stratofortress
  S/N 52-0003
  This is one of two modified
  for the X-15 project.
   (Used for 93 of the 199 flights)


There were a total of 199 X-15 flights between 8 June 1959 and 24 October 1968.

Where are the X-15's now?

Vehicle #1 is at the National Air and Space Museum. Vehicle #2 is at the US Air Force Museum in Dayton, Ohio. Vehicle #3 was destroyed in a crash and the recovered remains buried at an undisclosed location on Edwards Air Force Base, California.

NB-52A (S/N 52-0003, "The High and Mighty One") is currently located at the Pima Air and Space Museum in Tucson, Arizona. NB-52B (S/N 52-0008, "Balls 8") is located at Edwards Air Force Base in California.

X-15 Photos

x-15.jpg (5662 bytes) x-15_b52.jpg (9497 bytes) x-15_drop.jpg (7170 bytes) x-15_landing.jpg (8440 bytes)
x-15_dana.jpg (99315 bytes)
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x-15_knight.jpg (102019 bytes)
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x-15_white.jpg (116955 bytes)
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X-15 landing

(Flash - Click to play)
white_x-15.jpg (550199 bytes)
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Page last modified: 11 December 2016 16:24:36.