XB-70A-2-NA Valkyrie 62-0207 leading a formation of aircraft powered by General Electric engines. Joe Walker’s F-104 is just below the B-70’s right wing tip. (U.S. Air Force)
8 June 1966: During a publicity photo formation flight, a Lockheed F-104N Starfighter, N813NA, flown by NASA Chief Research Test Pilot Joseph A. Walker, was caught in the wingtip vortices of the North American Aviation XB-70A-2 Valkyrie, 62-0207, the second prototype Mach 3+ strategic bomber. The Starfighter rolled up and across the Valkyrie. The two airplanes collided, with the F-104 taking off the Valkyrie’s vertical fins, then exploding.
Lockheed F-104N N813NA collided with North American Aviation XB-70A-2 Valkyrie 62-0207 and exploded, 8 June 1966. (U.S. Air Force)
The Valkyrie continued to fly straight and level for 16 seconds before it began to roll inverted. The B-70’s pilot, Alvin S. White, was able to eject, though he was severely injured. Joe Walker and B-70 co-pilot Major Carl S. Cross, United States Air Force, were killed.
The B-70 is out of control and going down in this photograph. A large section of the left wing is missing. JP-8 fuel is spraying out of damaged tanks. (U.S. Air Force)
Still photographs and motion picture film of the formation were being taken from Clay Lacy’s Gates Lear Jet. The photos were for a General Electric publicity campaign showing U.S. military aircraft that were powered by GE engines. Air Force procedures for requesting and approval of publicity flights were not properly followed and it is likely this flight would not have been approved had they been.
The XB-70A-2 Valkyrie has rolled inverted and pitched nose down. The outer section of the left wing is missing. The trailing edge and tip tank of the Lear Jet photo plane’s right wing are in the foreground. (U.S. Air Force)
Reportedly, just prior to the collision, Walker radioed, “I’m opposing this mission. It is too turbulent and it has no scientific value.”
The wreckage of the North American Aviation XB-70A-2 Valkyrie 62-0207 burns on the desert floor at N. 35° 03′ 47″, W. 117° 01′ 27″, north of Barstow, California, 8 June 1966. (U.S. Air Force)
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)
Joseph Albert Walker in the cockpit of North American Aviation X-15A 56-6670, after a flight, 1960. (NASA)
24 March 1960: After North American Aviation’s Chief Engineering Test Pilot, Albert Scott Crossfield, had made the first flights in the new X-15 hypersonic research rocketplane (one gliding, eight powered), NASA Chief Research Test Pilot Joseph Albert Walker made his first familiarization flight.
The X-15, 56-6670, the first of three built by North American Aviation, Inc., was carried aloft under the right wing of a Boeing NB-52A Stratofortress, 52-003, flown by John E. Allavie and Fitzhugh L. Fulton.
Fitz Fulton and and Jack Allavie with a Boeing NB-52 drop ship. (Jet Pilot Overseas)
The rocketplane was dropped from the mothership over Rosamond Dry Lake at 15:43:23.0 local time, and Joe Walker ignited the Reaction Motors XLR-11 rocket engine. The engine burned for 272.0 seconds, accelerating Walker and the X-15 to Mach 2.0 (1,320 miles per hour/2,124.3 kilometers per hour) and a peak altitude of 48,630 feet (14,822.4 meters). Walker landed on Rogers Dry Lake at Edwards Air Force Base after a flight of 9 minutes, 8.0 seconds.
Joe Walker made 25 flights in the three X-15 rocket planes from 24 March 1960 to 22 August 1963. He achieved a maximum Mach number of 5.92, maximum speed of 4,104 miles per hour (6,605 kilometers per hour) and maximum altitude of 354,200 feet (107,960 meters).
Joe Walker with the Number 2 North American Aviation X-15, 56-6671, on Rogers Dry Lake. (NASA)
Joe Walker was killed in a mid-air collision between his Lockheed F-104N Starfighter and a North American Aviation XB-70A Valkyrie near Barstow, California, 1 June 1966.
The number one ship, 56-6670, made 81 of the 199 flights of the X-15 Program. It was the first to fly, and also the last, 24 October 1968. Today, it is in the collection of the Smithsonian Institution National Air and Space Museum.
North American Aviation, Inc. X-15A 56-6670 on Rogers Dry Lake, Edwards Air Force Base, California. (NASA)
Milton O. Thompson with a Lockheed JF-104A Starfighter at Edwards Air Force Base, circa 1962. The JF-104A is similar to the one he ejected from, 20 December 1962. (NASA)
20 December 1962: Milton Orville Thompson, a NASA test pilot assigned to the X-15 hypersonic research program, was conducting a weather check along the X-15’s planned flight path from Mud Lake, Nevada, to Edwards Air Force Base in California, scheduled for later in the day. Thompson was flying a Lockheed F-104A-10-LO Starfighter, Air Force serial number 56-749, call sign NASA 749.
NASA 749, a Lockheed JF-104A Starfighter, 56-749, with an ALSOR sounding rocket on a centerline mount, at Edwards Air Force Base. (NASA)
In his autobiography, At the Edge of Space, Thompson described the day:
“The morning of my weather flight was a classic desert winter morning. It was cold, freezing in fact, but the sky was crystal clear and there was not a hint of a breeze—a beautiful morning for a flight.”
Completing the weather reconnaissance mission, and with fuel remaining in the Starfighter’s tanks, Milt Thompson began practicing simulated X-15 approaches to the dry lake bed.
X-15 pilots used the F-104 to practice landing approaches. The two aircraft were almost the same size, and with speed brakes extended and the flaps lowered, an F-104 had almost the same lift-over-drag ratio as the X-15 in subsonic flight. Thompson’s first approach went fine and he climbed back to altitude for another practice landing.
Lockheed F-104A-10-LO Starfighter 56-749 (NASA 749) carrying an ALSOR sounding rocket on a centerline mount. (NASA)
When Milt Thompson extended the F-104’s flaps for the second simulated X-15 approach, he was at the “high key”— over Rogers Dry Lake at 35,000 feet (10,668 meters) — and supersonic. As he extended the speed brakes and lowered the flaps, NASA 749 began to roll to the left. With full aileron and rudder input, he was unable to stop the roll. Adding throttle to increase the airplane’s airspeed, he was just able to stop the roll with full opposite aileron.
Thompson found that he could maintain control as long as he stayed above 350 knots (402 miles per hour/648 kilometers per hour) but that was far too high a speed to land the airplane. He experimented with different control positions and throttle settings. He recycled the brake and flaps switches to see if he could get a response, but there was no change. He could see that the leading edge flaps were up and locked, but was unable to determine the position of the trailing edge flaps. He came to the conclusion that the trailing edge flaps were lowered to different angles.
Thompson called Joe Walker, NASA’s chief test pilot, on the radio and explained the situation:
I told him the symptoms of my problem and he decided that I had a split trailing edge flap situation with one down and one up.
He suggested I recycle the flap lever to the up position to attempt to get both flaps up and locked. I had already tried that, but I gave it another try. Joe asked if I had cycled the flap lever from the up to the takeoff position and then back again. I said no. I had only cycled the flap lever from the up position to a position just below it and then back to the up position. Joe suggested we try it his way. I moved the flap lever from the up position all the way to the takeoff position and then back to the up position. As soon as I moved the lever to the takeoff position, I knew I had done the wrong thing.
The airplane started rolling again, but this time I could not stop it. The roll rate quickly built up to the point that I was almost doing snap rolls. Simultaneously, the nose of the airplane started down. I was soon doing vertical rolls as the airspeed began rapidly increasing. I knew I had to get out quick because I did not want to eject supersonic and I was already passing through 0.9 Mach. I let go of the stick and reached for the ejection handle. I bent my head forward to see the handle and then I pulled it. Things were a blur from that point on.
—At the Edge of Space: The X-15 Flight Program, by Milton O. Thompson, Smithsonian Institution Press, Washington and London, 1992. Chapter 5 at Pages 119–120.
Impact crater caused by the crash and explosion of Milt Thompson’s Lockheed JF-104A Starfighter, 20 December 1962. (NASA)
As Thompson descended by parachute he watched the F-104 hit the ground and explode in the bombing range on the east side of Rogers Dry Lake. He wrote, “It was only 7:30 a.m. and still a beautiful morning.”
6 November 1958: NASA Research Test Pilot John B. (Jack) McKay made the final flight of the X-1 rocketplane program, which had begun twelve years earlier.
Bell X-1E 46-063 made its 26th and final flight after being dropped from a Boeing B-29 Superfortress over Edwards Air Force Base on a flight to test a new rocket fuel.
John B. McKay, NACA/NASA Research Test Pilot. (NASA)
When the aircraft was inspected after the flight, a crack was found in a structural bulkhead. A decision was made to retire the X-1E and the flight test program was ended.
The X-1E had been modified from the third XS-1, 46-063. It used a thinner wing and had an improved fuel system. The most obvious visible difference is the cockpit, which was changed to provide for an ejection seat. Hundreds of sensors were built into the aircraft’s surfaces to measure air pressure and temperature.
The Bell X-1E was 31 feet (9.449 meters) long, with a wingspan of 22 feet, 10 inches (6.960 meters). The rocketplane’s empty weight was 6,850 pounds (3,107 kilograms) and fully loaded, it weighed 14,750 pounds (6,690 kilograms). The rocketplane was powered by a Reaction Motors XLR11-RM-5 rocket engine which produced 6,000 pounds of thrust (26.689 kilonewtons). The engine burned ethyl alcohol and liquid oxygen. The X-1E carried enough propellants for 4 minutes, 45 seconds burn.
The Bell X-1E rocketplane being loaded into NACA 800, a Boeing B-29-96-BW Superfortress mothership, 45-21800, for another test flight. (NASA)
The early aircraft, the XS-1 (later redesignated X-1), which U.S. Air Force test pilot Charles E. (“Chuck”) Yeager flew faster than sound on 14 October 1947, were intended to explore flight in the high subsonic and low supersonic range. There were three X-1 rocketplanes. Yeager’s Glamorous Glennis was 46-062. The X-1D (which was destroyed in an accidental explosion after a single glide flight) and the X-1E were built to investigate the effects of frictional aerodynamic heating in the higher supersonic ranges from Mach 1 to Mach 2.
Bell X-1E 46-063 loaded aboard NACA 800, a Boeing B-29-96-BW Superfortress, 45-21800, circa 1955. (NASA)
The X-1E reached its fastest speed with NASA test pilot Joseph Albert Walker, at Mach 2.24 (1,450 miles per hour/2,334 kilometers per hour), 8 October 1957. Walker also flew it to its peak altitude, 70,046 feet (21,350 meters) on 14 May 1958.
NACA test pilot Joseph Albert Walker made 21 of the X-1E’s 26 flights. In this photograph, Joe Walker is wearing a David Clark Co. T-1 capstan-type partial-pressure suit with a K-1 helmet for protection at high altitudes. (NASA)
There were a total of 236 flights made by the X-1, X-1A, X-1B, X-1D and X-1E. The X-1 program was sponsored by the National Advisory Committee on Aeronautics, NACA, which became the National Aeronautics and Space Administration, NASA, on 29 June 1958.
