North American Aviation, Inc., X-15A-1 56-6670 hypersonic research rocketplane on display at the National Air and Space Museum. (Photo by Eric Long, National Air and Space Museum, Smithsonian Institution)
10 June 1969: The U.S. Air Force donated the first North American Aviation X-15, serial number 56-6670, to the Smithsonian Institution for display at the National Air and Space Museum.
The North American Aviation, Inc., X-15A-1, 56-6670, being brought into the Arts and Industries building, June 1969. The wings and sections of the dorsal and ventral fins have been removed. (Smithsonian Institution Archives SI-A-4145-23-A)
The first of three X-15A hypersonic research rocketplanes built by North American for the Air Force and the National Advisory Committee (NACA, the predecessor of NASA), 56-6670 made the first glide flight and the first and last powered flights of the X-15 Program. It made a total of 82 of the 199 X-15 flights.
Scott Crossfield, North American’s Chief Engineering Test Pilot, made the first unpowered flight 8 June 1959 and the first powered flight, 17 September 1959. NASA Research Test Pilot William H. “Bill” Dana made the final X-15 flight on 24 October 1968.
The first North American Aviation, Inc., X-15A, 56-6670, at the National Air and Space Museum, Washington, D.C. Above and behind the X-15 is the Douglas D558-II Skyrocket that Scott Crossfield flew to Mach 2.005, 20 November 1953. (D. Ramey Logan via Wikipedia)
30 April 1962: The Chief Research Test Pilot at NASA’s High Speed Flight Station, Joseph Albert Walker, flew the first North American Aviation X-15 hypersonic research aircraft, 56-6670, on its twenty-seventh flight. This was Flight 52 of the NASA X-15 Hypersonic Research Program. The purpose of this test flight was to explore aerodynamic heating and stability at very high altitudes.
At an altitude of approximately 45,000 feet (13,716 meters) over Mud Lake, Nevada, the X-15 was released from Balls 8, the NB-52B drop ship, at 10:23:20.0 a.m., Pacific Daylight Savings Time.
This NASA image depicts three X-15 flight profiles. Mud Lake, Nevada, is near the right edge of the image. (NASA)
Walker started the Reaction Motors XLR99-RM-1 rocket engine. The planned burn time was 81.0 seconds, but the engine ran slightly longer: 81.6 seconds. Even with the longer burn, the X-15 undershot the planned speed of Mach 5.35 and peak altitude of 255,000 feet (77,724 meters). The actual maximum speed for this flight was Mach 4.94, and maximum altitude, 246,700 feet (75,194 meters). Walker landed on Rogers Dry Lake. The total duration of Flight 52 was 9 minutes, 46.2 seconds.
Even though the peak altitude reached by the X-15 was 8,300 feet (2,530 meters) lower than expected, Joe Walker established a new Fédération Aéronautique Internationale (FAI) World Record for Altitude Gain, Aeroplane Launched from a Carrier Aircraft, of 61,493 meters (201,749 feet).¹
Joe Walker with the Number 2 North American Aviation X-15, 56-6671, on Rogers Dry Lake. Walker is wearing a David Clark Co. MC-2 full-pressure suit (NASA)
20 April 1962: “Neil’s Cross-Country.” NASA Research Test Pilot Neil Alden Armstrong conducts a flight to test the Minneapolis-Honeywell MH-96 flight control system installed in the third North American Aviation X-15, serial number 56-6672. The new system combined both aerodynamic and reaction thruster flight controls in one hand controller rather than the two used in X-15s -670 and -671, simplifying the tasks for the pilot.
On its fourth flight, -672 was air-dropped from the Boeing NB-52B Stratofortress drop ship, Balls 8, over Mud Lake, Nevada. Armstrong fired the Reaction Motors XLR99-RM-1 engine and let it burn for 82.4 seconds. The X-15 accelerated to Mach 5.31 (3,789 miles per hour/6,098 kilometers per hour). After the engine was shut down, the rocketplane continued to its peak altitude on a ballistic trajectory, reaching 207,500 feet (63,246 meters) before going over the top and beginning its descent back toward the atmosphere. The test of the new flight control system went well.
Neil Armstrong began to pull out of the descent at about 100,000 feet (30,480 meters), but the X-15 “ricocheted” off the top of the atmosphere and climbed back to 115,000 feet (35,052 meters) where the aerodynamic control surfaces could not function. He used the reaction thrusters to turn toward the dry lake landing area at Edwards Air Force Base, but although the X-15 rolled into a left bank, it would not change direction and still in ballistic flight, went zooming by Edwards at Mach 3 and 100,000 feet in a 90° left bank.
As the X-15 dropped back into the atmosphere, Armstrong was finally able to get it slowed down, but he was far south of his planned landing site. By the time he got -672 turned around he was 45 miles (72.4 kilometers) to the south, over the Rose Bowl in Pasadena, and gliding through 45,000 feet (13,716 meters). There was real doubt that he would be able to make the X-15 stretch its glide to reach the dry lake.
In a masterful display of airmanship, Neil Armstrong was able to get the X-15 to reach the south end of the dry lake, 12 miles (19.3 kilometers) from the planned landing spot to the north. But it was a very close call. In debriefing, the pilots of the four F-104 chase planes were asked how much clearance Armstrong had as he crossed over the Joshua trees at the edge of the lake bed. One of them answered, “Oh, at least 100 feet—on either side.”
At 12 minutes, 28.7 seconds, this was the longest flight of the entire X-15 program. It is called “Neil’s cross-country flight.”
A U.S. Navy fighter pilot who flew 78 combat missions during the Korean War, Neil Armstrong became a civilian test pilot at NACA (National Advisory Committee on Aeronautics, the predecessor to NASA) in 1955. He made 7 flights in the X-15 before transferring to NASA’s Project Gemini in 1962.
Armstrong was command pilot for Gemini 8 and Gemini 11, commander of the backup flight crew of the Apollo 8 mission, and was commander of Apollo 11.
On 20 July 1969, Neil Alden Armstrong was the First Man To Stand on the Surface of The Moon.
