4 August 1960: NASA research test pilot Joseph Albert Walker set an unofficial world speed record when he flew the number one North American Aviation X-15, 56-6670, to 2,195 miles per hour (3,532.5 kilometers per hour). This was the 18th flight of the X-15 Program. It was 56-6670’s eighth flight and Walker’s fourth X-15 flight. The purpose of this test was to gradually increase the rocket plane’s speed toward its design limit.
Airdropped from the Boeing NB-52A Stratofortress mothership, 52-003, over Silver Lake, near the California-Nevada border, at 08:59:13.0 a.m., PDT, Walker fired the X-15’s two Reaction Motors XLR11-RM-13 rocket engines for 264.2 seconds. The X-15 accelerated to Mach 3.31 and climbed to a peak altitude of 78,112 feet (23,810 meters). [The two XLR11s were used as an interim powerplant until the Reaction Motors XLR99 was ready. The combined thrust of both LR11s was only slightly more than the idle thrust of the XLR99.]
Walker touched down on Rogers Dry Lake at Edwards Air Force Base, California, after a flight of 10 minutes, 22.6 seconds.
Joe Walker with X-15 56-6670 on Rogers Dry Lake. (NASA)
With Major Robert M. White and the X-15 under its right wing, the Boeing NB-52A Stratofortress, 52-003, takes of from Edwards Air Force Base, 17 July 1962. The rocketplane’s belly is covered with frost from the cryogenic propellants. (U.S. Air Force)
17 July 1962: At 9:31:10.0 a.m., the Number 3 North American Aviation X-15, 56-6672, was airdropped from a Boeing NB-52A Stratofortress, 52-003, over Delamar Dry Lake, Nevada. Air Force project test pilot Major Robert M. (“Bob”) White was in the cockpit. This was the 62nd flight of the X-15 Program, and Bob White was making his 15th flight in an X-15 hypersonic research rocketplane. The purpose of this flight was to verify the performance of the Honeywell MH-96 flight control system which had been installed in the Number 3 ship. Just one minute before drop, the MH-96 failed, but White reset his circuit breakers and it came back on line.
North American Aviation X-15 56-6672 immediately after being dropped by the Boeing NB-52 Stratofortress. (NASA)
After dropping from the B-52’s wing, White fired the X-15’s Reaction Motors XLR-99 rocket engine and began to accelerate and climb. The planned burn time for the 57,000-pound-thrust engine was 80.0 seconds. It shut down 2 seconds late, driving the X-15 well beyond the planned peak altitude for this flight. Instead of reaching 280,000 feet (85,344 meters), Robert White reached 314,750 feet (95,936 meters). This was an altitude gain of 82,190 meters (269,652 feet), which was a new Fédération Aéronautique Internationale (FAI) World Record for Altitude Gain, Aeroplane Launched from a Carrier Aircraft.¹ (The B-52 typically launched the X-15 from an altitude of about 45,000 feet (13,716 meters.) The rocketplane reached Mach 5.45, 3,832 miles per hour (6,167 kilometers per hour).
Because of the increased speed and altitude, White was in danger of overshooting his landing at Edwards Air Force Base in California. He passed over the north end of Rogers Dry Lake and crossed the “high key”—the point where the X-15 landing maneuver begins—too high and too fast at Mach 3.5 at 80,000 feet (24,384 meters). Without power, White made a wide 360° turn over Rosamond Dry Lake then came back over the high key at a more normal 28,000 feet (8,534.4 meters) and subsonic speed. He glided to a perfect touch down, 10 minutes, 20.7 seconds after being dropped from the B-52.
North American Aviation X-15 56-6672 just before touchdown on Rogers Dry Lake. A Lockheed F-104 Starfighter chase plane escorts it. The green smoke helps the pilots judge wind direction and speed. (NASA)
This was the first time that a manned aircraft had gone higher than 300,000 feet (91,440 meters). It was also the first flight above 50 miles. For that achievement, Bob White became the first X-15 pilot to be awarded U.S. Air Force astronaut wings.
Command Pilot Astronaut insignia, United States Air Force
Major White had been the first pilot to fly faster than Mach 4, Mach 5 and Mach 6. He was the first to fly over 200,000 feet, then over 300,000 feet. He was a graduate of the Air Force Experimental Test Pilot School and flew tests of many aircraft at Edwards before entering the X-15 program. He made at total of sixteen X-15 flights.
A P-51 Mustang fighter pilot with the 355th Fighter Group in World War II, he was shot down by ground fire on his fifty-third combat mission, 23 February 1945, and captured. He was held as a prisoner of war until the war in Europe came to an end in April 1945.
After the war, White accepted a reserve commission while he attended college to earn a degree in engineering. He was recalled to active duty during the Korean War, and assigned to a P-51 fighter squadron in South Korea. Later, he commanded the 22nd Tactical Fighter Squadron (flying the Republic F-105 Thunderchief supersonic fighter bomber) based in Germany, and later, the 53rd TFS. During the Vietnam War, Lieutenant Colonel White, as the deputy commander for operations of the 355th Tactical Fighter Wing, flew seventy combat missions over North Vietnam in the F-105D, including leading the attack against the Paul Doumer Bridge at Hanoi, 11 August 1967, for which he was awarded the Air Force Cross.
He next went to Wright-Patterson AFB where he was director of the F-15 Eagle fighter program. In 1970 he returned to Edwards AFB as commander of the Air Force Flight Test Center. White was promoted to Major General in 1975.
General White retired from the U.S. Air Force in 1981. He died 10 March 2010.
Major Robert M. White, U.S. Air Force, with a North American Aviation X-15 on Rogers Dry Lake, 1961. (NASA)
Bob White exits the cockpit of an X-15 on Rogers Dry Lake. (NASA)
23 June 1961: Major Robert Michael White, United States Air Force, became the first pilot to exceed Mach 5 in an aircraft. This was the 38th flight of the X-15 Program. Flights during this phase incrementally increased the speed and altitude of the X-15 up to its design limits of Mach 6 and 250,000 feet (76,200 meters).
The second North American Aviation X-15A, 56-6671, was air-dropped from the NB-52A Stratofortress mothership, 52-003, over Mud Lake, Nevada at 2:00:05.0 p.m., Pacific Daylight Time (21:00 UTC). White fired the Reaction Motors XLR99-RM-1 engine for 78.7 seconds, reaching Mach 5.27 (3,603 miles per hour, 5,799 kilometers per hour) and climbed to 107,700 feet (32,827 meters). 10 minutes, 5.7 seconds after being dropped from the B-52, White touched down on Rogers Dry Lake at Edwards Air Force Base.
Bob White was the first pilot to exceed Mach 4, Mach 5 and Mach 6. He also flew an X-15 to an altitude of 314,750 feet (95,936 meters), qualifying for U.S. Air Force astronaut wings.
After leaving the X-15 program, Major White flew 70 combat missions in the Republic F-105D Thunderchief fighter bomber during the Vietnam War. He lead the attack against the heavily-defended Paul Doumer Bridge in Hanoi, 11 August 1967, for which he was awarded the Air Force Cross.
Major General White retired from the U.S. Air Force in 1981. He died 10 March 2010.
56-6671 is in the collection of the National Museum of the United States Air Force. The mothership, 52-003, is on display at the Pima Air and Space Museum, Tucson, Arizona.
