5 December 1963: On Flight 97 of the X-15 Program, Major Robert A. Rushworth flew the number one aircraft, Air Force serial number 56-6670, to an altitude of 101,000 feet 30,785 meters) and reached Mach 6.06 (4,018 miles per hour/6,466 kilometers per hour).
The rocketplane was dropped from the Boeing NB-52B Stratofortress “mother ship” 52-008, Balls 8, flying at 450 knots (833.4 kilometers per hour) at 45,000 feet (13,716 meters) over Delamar Dry Lake, Nevada. Rushworth ignited the Reaction Motors XLR-99-RM-1 rocket engine, which burned for 81.2 seconds before shutting down.
The flight plan had called for an altitude of 104,000 feet (31,699 meters), a 78 second burn and a maximum speed of Mach 5.70. With the difficulties of flying such a powerful rocketplane, Rushworth’s flight was actually fairly close to plan. During the flight the right inner windshield cracked.
Bob Rushworth landed the X-15 on Rogers Dry Lake at Edwards Air Force Base, California, after a flight of 9 minutes, 34.0 seconds.
Mach 6.06 was the highest Mach number reached for an unmodified X-15.
56-6670 flew 81 of the 199 flights of the X-15 Program. It is in the collection of the Smithsonian Institution National Air and Space Museum.
From 1960 to 1966, Bob Rushworth made 34 flights in the three X-15s, more than any other pilot.
29 November 1957: The third production Boeing B-52A-1-BO Stratofortress strategic bomber, 52-003, was flown from Boeing’s Seattle plant to the North American Aviation facility at Air Force Plant 42, Palmdale, California, to be modified to carry the new X-15 hypersonic research rocketplane.
Modifications began on 4 February 1958. A pylon was mounted under the bomber’s right wing. A large notch was cut into the trailing edge of the inboard flap for the X-15’s vertical fin. A 1,500 gallon (5,678 liter) liquid oxygen tank was installed in the bomb bay.
A station for a launch operator was installed on the upper deck of the B-52 at the former electronic countermeasures position. A series of control panels allowed the panel operator to monitor the X-15’s systems, provide electrical power, and to keep the rocketplane’s liquid oxygen tank full as the LOX boiled off during the climb to launch altitude. The operator could see the X-15 through a plexiglas dome, and there were two television monitors.
After modifications were completed at Palmdale, 52-003 was flown to Edwards Air Force Base, 14 November 1958.
NB-52A 52-003 is on display at the Pima Air and Space Museum, Tucson, Arizona.
15 November 1967: Major Michael James Adams, United States Air Force, was killed in the crash of the number three North American Aviation X-15 hypersonic research rocketplane, 56-6672.
Flight 191 of the X-15 program was Mike Adams’ seventh flight in the rocketplane. It was the 56-6672’s 65th flight. The flight plan called for 79 seconds of engine burn, accelerating the X-15 to Mach 5.10 while climbing to 250,000 feet (76,200 meters). Adams’ wife, Freida, and his mother, Georgia Adams, were visiting in the NASA control room at Edwards Air Force Base.
Balls 8, the Boeing NB-52B Stratofortress, 52-008, flown by Colonel Joe Cotton, took off from Edwards at 9:12 a.m., carrying -672 on a pylon under its right wing, and headed north toward the drop point over Delamar Dry Lake in Nevada. The drop ship climbed to the launch altitude of 45,000 feet (13,716 meters).
The X-15 launch was delayed while waiting for the Lockheed C-130 Hercules rescue aircraft to arrive on station. This required Adams to reset the Honeywell MH-96 Automatic Flight Control System to compensate for the changing position of the sun in the sky.
56-6672 was launched by Balls 8 at 10:30:07.4 a.m., Pacific Standard Time. As it dropped clear of the bomber, the rocketplane rolled 20° to the right, a normal reaction. Within one second, Mike Adams had started the XLR99-RM-1 rocket engine while bringing the wings level. The engine ignited within one-half second and was up to its full 57,000 pounds of thrust (253.549 kilonewtons) one second later. The engine ran for 82.3 seconds, 3.3 seconds longer than planned, causing the X-15 to reach Mach 5.20 (3,617 miles per hour/5,821 kilometers per hour) and to overshoot the planned altitude to peak at 266,000 feet (81,077 meters).
With the X-15 climbing through 140,000 feet (42,672 meters), the Inertial Flight Data System computer malfunctioned. Adams radioed ground controllers that the system’s malfunction lights had come on.
The flight plan called for a wing-rocking maneuver at peak altitude so that a camera on board could scan from horizon to horizon. During this maneuver, the Reaction Control System thrusters did not respond properly to Adams’ control inputs. The X-15 began to yaw to the right.
As it reached its peak altitude, 56-6672 yawed 15° to the left. Going over the top, the nose yawed right, then went to the left again. By the time the aircraft has descended to 230,000 feet (70,104 meters), it had pitched 40° nose up and yawed 90° to the right its flight path. The X-15 was also rolling at 20° per second. The rocketplane went into a spin at Mach 5.
10:33:37 Chase 1: “Dampers still on, Mike?”
10:33:39 Adams: “Yeah, and it seems squirrelly.”
10:34:02 Adams: “I’m in a spin, Pete.” [Major William J. “Pete” Knight, another X-15 pilot, was the flight controller, NASA 1]
10:34:05 NASA 1: “Let’s get your experiment in and the cameras on.”
10:34:13 NASA 1: “Let’s watch your theta, Mike.”
10:34:16 Adams: “I’m in a spin.”
10:34:18 NASA 1: “Say again.”
10:34:19 Adams: “I’m in a spin.”
Adams fought to recover, and at 118,000 feet (35,967 meters) came out of the spin, but he was in an inverted 45° dive at Mach 4.7. The X-15’s MH-96 Automatic Flight Control System entered a series of diverging oscillations in the pitch and roll axes, with accelerations up to 15 gs. Dynamic pressures on the airframe rapidly increased from 200 pounds per square foot (9.576 kilopascals) to 1,300 pounds per square foot (62.244 kilopascals).
At 62,000 feet (18,898 meters), still at Mach 3.93, the aircraft structure failed and it broke apart.
10:34:59 X-15 telemetry failed. Last data indicated it was oscillating +/- 13 g. Radar altitude was 62,000 feet (18,898 meters). The aircraft was descending at 2,500 feet per second (762 meters per second) and broke into many pieces at this time.
10:35:42 NASA 1: “Chase 4, do you have anything on him?”
10:35:44 Chase 4: “Chase 4, negative.”
10:35:47 NASA 1: “OK, Mike, do you read?”
10:35:52 Chase 4: “Pete, I got dust on the lake down there.”
North American Aviation X-15A-3 56-6672 crashed in a remote area, approximately 5½ miles (9 kilometers) north-northeast of Randsburg, California, a small village along U.S. Highway 395.
Major Michael James Adams was killed. This was the only pilot fatality of the entire 199-flight X-15 program.
An investigation by NASA’s Engineering and Safety Center determined that,
“. . . the root cause of the accident was an electrical disturbance originating from an experiment package using a commercial-off-the-shelf (COTS) component that had not been properly qualified for the X-15 environment. . .”and that there is“. . . no conclusive evidence to support the hypothesis that SD [spatial disorientation] was a causal factor. On the contrary, the evidence suggests that poor design of the pilot-aircraft interface and ineffective operational procedures prevented the pilot and ground control from recognizing and isolating the numerous failures before the aircraft’s departure from controlled flight was inevitable.”
—A Comprehensive Analysis of the X-15 Flight 3-65 Accident, NASA/TM—2014-218538 (Corrected Copy)
Michael James Adams was born at Sacramento, California, 5 May 1930. He was the first of two sons of Michael Louis Adams, a telephone company technician, and Georgia E. Domingos Adams.
After high school, Mike Adams attended Sacramento Junior College, graduating in 1949. He was an outfielder for the college baseball team, and threw the javelin in track & field.
Adams enlisted in the United States Air Force in 1950. He completed basic training at Lackland Air Force Base, San Antonio, Texas. In October 1951, he was selected as an aviation cadet and sent to Spence Air Force Base, near Moultrie, Georgia, for primary flight training. Cadet Adams completed flight training at Webb Air Force Base, Big Spring, Texas. He graduated 25 October 1952. Adams was one of two distinguished graduates in his class and received a commission as an officer in the regular Air Force.
Second Lieutenant Adams was assigned to advanced flight training at Nellis Air Force Base, where he flew the Lockheed F-80 Shooting Star and North American Aviation F-86 Sabre.
In April 1953, Lieutenant Adams joined the 80th Fighter-Bomber Squadron at K-13, Suwon, Republic of Korea. He flew 49 combat missions.
Following the Korean War, Lieutenant Adams was assigned to the 613th Fighter Bomber Squadron, 401st Fighter-Bomber Group, at England Air Force Base, Alexandria, Louisiana. The Squadron initially flew the F-86F Sabre and then transitioned to the Republic F-84F Thunderstreak. Adams deployed to Chaumont Air Base, France, for a six-month temporary assignment.
While stationed at England AFB, Lieutenant Adams met Miss Freida Beard. They were married in a ceremony at the Homewood Baptist Church in Alexandria, 15 January 1955. They would have three children, Michael James, Jr., Brent, and Liese Faye Adams.
In 1958, Adams graduated from the University of Oklahoma at Norman, with a bachelor’s degree in aeronautical engineering. He was a member of the university’s Institute of Aeronautical Sciences. Adams was next assigned to the Massachusetts Institute of Technology, Cambridge, Massachusetts, where he studied astronautics.
Adams’ next military assignment was as a maintenance officer course instructor at Chanute Air Force Base, Rantoul, Illinois.
In 1962, Captain Adams entered an eight-month training program at the Air Force Test Pilot School, Class 62C, at Edwards Air Force Base in the high desert of southern California. He was awarded the A.B. Honts Trophy as the class’s outstanding graduate.
On 17 June 1963, Captain Adams entered the Aerospace Research Pilots School, which was also at Edwards. This was a seven-month course that taught flying skills in advanced vehicles, with an aim to prepare the graduates for space flight, and to create a pool of qualified military test pilots to be selected as astronauts. The Air Force estimated a need for 20 pilots a year for the upcoming X-20 Dyna-Soar and Manned Orbiting Laboratory (M.O.L.) programs. Adams graduated with the second of the four ARPS classes.
Adams then became an operational test pilot, conducting stability and control tests for the Northrop F-5A Freedom Fighter. That was followed by an assignment as a project pilot for the Cornell Aeronautical Laboratory.
On 13 November 1963, it was announced that Michael Adams was on of the selectees for the M.O.L. program. As a designated Air Force astronaut, Adams was involved in lunar landing simulations during the development of the Apollo Program lunar lander.
Major Adams was selected as a pilot of the NASA/Air Force X-15 Hypersonic Research Flight Program. (He was the twelfth and final pilot to be accepted into the project.) He made his first X-15 flight on 6 October 1966. He flew the first X-15, 56-6770. A ruptured fuel tank forced him to make an emergency landing at Cuddeback Dry Lake, one of several pre-selected emergency landing sites, about 40 miles (64 kilometers) northeast of Edwards. The duration of the flight was 8 minutes, 26.4 seconds. The X-15 had only reached an altitude of 75,400 feet (22,982 meters) and Mach 3.00.
His second flight took place on 29 November 1966. On this flight, he took the # 3 ship, 56-6672, to 92,100 feet (28,072 meters) and Mach 4.65. The flight lasted 7 minutes, 55.9 seconds.
For his third flight, Mike Adams was back in 56-6670, which had been repaired. He flew to an altitude of 133,100 feet (40,569 meters) and reached Mach 5.59 (3,822 miles per hour/6,151 kilometers per hour). This was Adams fastest flight. He landed at Edwards after 9 minutes, 27.9 seconds.
Flight number four for Adams took place on 28 April 1967. Again he flew the # 1 X-15. On this flight, he reached 167,200 feet (50,963 meters) and Mach 5.44. Elapsed time was 9 minutes, 16.0 seconds.
On 15 June 1967, Adams flew # 1 to 229,300 feet (69,891 meters) and Mach 5.14. Duration 9 minutes, 11.0 seconds.
On 25 August 1967, Adams made his sixth flight, his second in the third X-15, 56-6672. The rocket engine shut down after sixteen seconds and had to be restarted. The maximum altitude was 84,400 feet (25,725 meters) and Mach 4.63. The duration of this flight was 7 minutes. 37.0 seconds.
Mike Adams’ seventh flight in an X-15 took place 15 November 1967. This was the 191st X-15 flight, and the 65th for X-15 56-6672. Tests to be conducted were an ultraviolet study of the rocketplane’s exhaust plume; solar spectrum measurements; micrometeorite collection, and a test of ablative material for the Saturn rocket.
Adams reached 266,000 feet (81,077 meters) and Mach 5.20.
Having met the U.S. Air Force qualification for flight in excess of 50 miles (80.47 kilometers), Michael Adams was posthumously awarded the wings of an astronaut.
Major Michael James Adams, United States Air Force, was buried at Mulhearn Memorial Park, in Monroe, Louisiana.
9 November 1962: Flight 74 of the X-15 Program was the Number Two aircraft’s 31st flight. X-15 56-6671 was carried aloft by Balls 8, the Boeing NB-52B Stratofortress, 53-008, for launch over Mud Lake, Nevada. NASA test pilot John Barron (“Jack”) McKay was to take the rocketplane to 125,000 feet at Mach 5.5 to investigate the stability and handling of the X-15 with the lower half of the ventral fin removed, and to investigate aerodynamic boundary layer phenomena.
The B-52 mothership dropped Jack McKay and the X-15 right on schedule at 10:23:07.0 a.m., local time, from an altitude of 45,000 feet (13,716 meters) and speed of approximately 450 knots (833 kilometers per hour). McKay advanced the throttle to ignite the Reaction Motors XLR99-RM-1 rocket engine. It fired immediately but when McKay advanced the throttle for the full 57,000 pounds of thrust, the engine remained at just 30%.
The X-15 could have flown back to Edwards Air Force Base, about 200 miles (320 kilometers) to the south, but with the engine not responding to the throttle, it was uncertain that it would continue running. The decision was made to make an emergency landing at Mud Lake.
Having reached a peak altitude of 53,950 feet (16,444 meters) and Mach 1.49 (1,109 miles per hour/1,785 kilometers per hour), Jack McKay continued to circle the lake burning off propellants as he lost altitude. The engine was shut down at 70.5 seconds. McKay positioned the aircraft for landing as he continued to dump unused propellant and liquid oxygen, but a considerable amount remained on board.
As he neared touchdown, he tried to lower the flaps but they did not deploy. The X-15 touched down on the dry lake bed at 296 miles per hour (476.4 kilometers per hour), 66 miles per hour (106 kilometers per hour) faster than normal.
Duration of the flight from air launch to touchdown was 6 minutes, 31.1 seconds.
The high speed and extra weight caused the X-15’s rear skids to hit harder than normal. When the nose wheels hit, a rebound effect placed even higher loads on the rear struts. At the same time, with the elevators in an extreme nose-up position, the higher aerodynamic loads pushed the skids deeper into the lake bed. This higher loading caused the left rear strut to collapse. The X-15 rolled to the left and the left elevator dug into the lake bed. This caused the aircraft to start sliding to the left. Jack McKay jettisoned the canopy and as the right wing tip dug into the surface, the X-15 flipped over and came to rest upside down.
McKay was seriously injured. He was trapped in the upside down X-15 and was in danger from the vapors of the ammonia propellants and liquid oxygen. An H-21 rescue helicopter hovered overhead to blow the vapor away.
Prior to the flight, an Air Force C-130 had brought a fire engine and crew to standby at Mud Lake, returned to Edwards and picked up a second fire engine and its crew, then remained airborne should an emergency landing be made at another intermediate dry lake.
These propositioned emergency assets were able to rescue McKay and to transport him to the hospital back at Edwards.
McKay eventually recovered sufficiently to return to flight status, but ultimately his injuries forced him to retire.
The Number Two X-15 was severely damaged. It was taken back to North American and was rebuilt into the X-15A-2, intended to reach speeds up to Mach 8. It would be more than a year and a half before it flew again.
9 November 1961: Major Robert M. White, U.S. Air Force, became the first pilot to fly faster than Mach 6 when he flew the number two North American Aviation X-15 hypersonic research rocketplane, 56-6671, to Mach 6.04.
This was the 45th flight of the X-15 program, and Bob White’s 11th flight. The purpose of this test flight was to accelerate 56-6671 to its maximum velocity, to gather data about aerodynamic heating at hypersonic speeds, and to evaluate the rocketplane’s stability and handling.
The X-15 was carried to approximately 45,000 feet (13,716 meters) while mounted to a pylon under the right wing of the “mothership,” a Boeing NB-52B Stratofortress, 52-008, nicknamed Balls 8. White was dropped over Mud Lake, Nevada, approximately 200 miles (322 kilometers) north of Edwards Air Force Base. Once clear of the B-52, he ignited the Reaction Motors XLR99-RM-1 rocket engine, and with it producing 57,000 pounds of thrust (253.549 kilonewtons) at full throttle, the X-15 accelerated for 86.9 seconds. The rocketplane reached a peak altitude of 101,600 feet (30,968 meters). Its speed was Mach 6.04 (4,094 miles per hour/6,589 kilometers per hour).
White stated in his post-flight report, “When I leveled off at about 101,000 feet, I made a little downward pressure [on the control stick], because I didn’t want to be climbing. I remember . . . going along watching that [Mach] meter reading roughly 6,000 feet per second,[and] saying to myself, ‘Go, go, go, go!’ We did just crack it, because we knew that bringing all the proper things together, we could or should get just about Mach 6.”
In order to achieve the goal, the flight plan called for pushing the LR-99 to the point of exhaustion instead of manually shutting down the engine at an arbitrary point. White said, “The shutdown seemed to be a little bit different this time, compared with a shutdown by closing the throttle. It seemed to occur over a longer time interval.”
— The X-15 Rocket Plane: Flying the First Wings into Space, by Michelle Evans, University of Nebraska Press, Lincoln and London, 2013, Chapter 3 at Page 87.
“The airplane really did get hot on those flights. Temperatures in excess of 1,300 °F. were recorded. Parts of the airplane glowed cherry red and softened up a bit during those flights. The airplane got so damned hot that it popped and banged like an old iron stove. It spewed smoke out of its bowels and it twitched like frog legs in a skillet. But it survived.”
— At the Edge of Space: The X-15 Flight Program, by Milton O. Thompson, Smithsonian Institution Press, Washington, 1992, at Page 98.
As the X-15 decelerated through Mach 2.4, the right side windshield shattered, leaving it completely opaque. On Bob White’s previous flight, the left windshield had also broken. Fortunately, in both cases, only the outer layer of the dual pane glass broke. The reduced visibility made the approach difficult to judge, but White made a successful landing, touching down on Rogers Dry Lake after a flight of 9 minutes, 31.2 seconds duration.
A P-51 Mustang fighter pilot in World War II, Robert M. White was shot down on his 52nd combat mission in February 1945 and captured. He was held as a prisoner of war until the war in Europe came to an end in April 1945. White was recalled to active duty during the Korean War. 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.
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 made at total of sixteen X-15 flights.
After leaving the X-15 program, Bob White returned to operational duties. Later, he flew 70 combat missions over North Vietnam in the Republic F-105 Thunderchief supersonic fighter bomber, 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 systems program. 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.