North American X-15

The U.S. test aircraft X-15 was a rocket-powered experimental aircraft for high altitude and high-speed flights. The company North American Aviation (NAA ) built three copies of this pattern. New records were set for manned aircraft with this machine back in the 1960s. It has a maximum speed of 7274 km / h (Mach 6.72 ) and an altitude of 107 960 m. The data collected served the U.S. space program, such as the Space Shuttle. Higher speeds and heights manned aircraft have been achieved only by the space shuttle in 1981.

  • 3.1 According to the U.S. definition of eight astronauts
  • 3.2 According to international definition, only a spaceman
  • 3.3 Two more pilots were later spaceman


The single-seat aircraft had a number of technical features to meet the extreme flight conditions meet. The structure consisted of titanium or steel, an outer skin made of Inconel X, which can withstand temperatures of up to 650 ° C. The reason for this was that the temperature stability was a major problem as the lightweight construction. The aircraft was launched from the air of a converted B- 52 bomber NASA and ended up with his own chassis. In addition to the aerodynamic surfaces for controlling the atmosphere in a reaction control system was installed to allow maneuverability of the outside atmosphere.

In just 3 minutes, the variable Thiokol single-chamber liquid-fuel rocket engine XLR99 - RM2 by Reaction Motors spent ( thrust: 254 kN ( 57000 lbf ) at sea level, 311 kN (70000 lbf ) at peak height ) of the X -15A -2 about 15 tons rocket fuel. The fuel consisted of ammonia and liquid hydrogen peroxide from oxygen and to drive the high-power turbo- pumps, the pressed-in this fuel into the combustion chamber. The rocket plane put it in a typical test flight covering a distance of 450 km. So that it did not break in the air during the flight could not exceed the maximum stress of -3.0 7.33 g and g. For the quickest flights an ablative heat shield was applied.

The rear suspension consisted of lack of space and to reduce the weight of skids. Otherwise, the construction of the missile is similar in many respects the German A9, a manned edition of the A4, which is also not surprising, because the X-15 is based on the Walter Dornberger for the NACA developed concept of a hypersonic research aircraft. Walter Dornberger was the military leader of the Peenemunde V- 2 program.


Development and construction

After the " Research Committee Airplain " on December 30, 1954 12 aircraft manufacturers presented the project could until May 9, 1955, four companies - the Bell Aircraft Corporation, Republic Aviation Company, North American Aviation and Douglas - to submit their designs for the three specimens. On December 6, 1955, the order to the North American Aviation was awarded, although their design was by far more expensive than the other manufacturers. One reason why it was decided to NAA was that they wanted to use instead of the magnesium alloy Elektron Inconel X as the outer skin. In September 1956 NAA began with the construction of three copies. In December of the same year, the first mock-up was completed.

Test flights

On October 15, 1958, the rollout of the first copy was made. On March 10, 1959, the first test flight was made, but still without separation from the carrier aircraft. As such, a converted B- 52A and B- 52B were used, which were named after their modification NB- 52A or NB- 52B. On June 8 of the same year was carried out with the first engine- free copy of the first glide. On September 17, 1959, the second X-15 first flew with rocket propulsion, but initially with two pieces of the weaker engine Reaction Motors XLR -11, yet it reached a speed of 2242 km / h

In the summer of the following year, the X-15 No. 3 was converted, the single engine Reaction Motors XLR99 was installed, so that the aircraft could fly at speeds that were greater than Mach 4 After the conversion of the X-15 # 3 followed a little later, the first two versions. On November 15, 1960, the first flight was followed with the modified X 15th

After it came in the second specimen as a result of engine damage on November 9, 1962 a crash landing, it was decided that X-15 No. 2 to the bigger X -15A -2 remodel, which among other things, 67 inches longer and because of the two was added droppable external tanks also much heavier. In June 1964, the first flight with the X -15A -2.

With her and the pilot William John Knight was born on October 3, 1967 set up ( with XLR -99), a speed record: 7274 km / h ( at a height of 59 km). The test flight but had to be canceled and ended with an emergency landing. The altitude record for X-15, however, was flown on 19 July 1963 with the X-15 # 3. He was 107 960 meters.

On November 15, 1967, the third copy of the X-15 lost during re-entry from about 80 km altitude, the longitudinal stability and broke under the aerodynamic forces that were ± 15 g, significantly more than the X-15 could stand. The pilot, Major Michael Adams, it was killed. It was the 191st flight of an X - 15th

The last flight of X-15 took place with the first copy on 24 October 1968. A total of 199 flights were performed.

The two remaining machines are on display in the Smithsonian Air and Space Museum in Washington DC and in the United States Air Force Museum in Dayton, Ohio.

Overall, the project, hardware and software costs added together cost 300 million U.S. dollars. A proposed NAA enhanced version X-15 -3 with delta wings and ramjet propulsion was not realized.


Astronaut status

According to U.S. definition eight spaceman

At 13 flights of 17 July 1962 to 21 August 1968, amounting to over 50 miles ( about 80 kilometers ) has been reached. By definition, the U.S. Air Force there begins the space, so that the eight pilots of these flights were considered spaceman. The five military pilots Robert White, Robert Rushworth, Joe Engle, William John Knight and Michael Adams received therefor by the U.S. Air Force astronaut wings as an award. For the three civilian pilots this was rescheduled until 24 August 2005. Bill Dana accepted the award itself and greet the deceased pilot Joe Walker and John B. McKay were represented by family members.

According to international definition, only a spaceman

By the definition of the Fédération Aéronautique Internationale (FAI ) is the boundary to space at 100 km. Only two of the X -15 flights exceeded this limit: Flight 90 on 19 July 1963 106 010 m and Flight 91 on 22 August 1963, 107 960 m. Both times the pilot Joe Walker, so that he, according to the international definition, the only pilot was that reached the outer space with the X-15.

Two more pilots were later spaceman

The X -15 pilot Neil Armstrong and Joe Engle later switched to the Space Program at NASA and reached there spaceman status. Armstrong became the first man to the moon, Engle commanded two flights of the Space Shuttle.