Tag Archives: Joseph Albert Walker

22 August 1963

Joe Walker and the X-15 on Rogers Dry Lake at the end of a flight. Walker is wearing a David Clark Co. MC-2 full-pressure suit. (U.S. Air Force)

22 August 1963: On his twenty-fifth and last flight with the X-15 program, NASA Chief Research Test Pilot Joseph Albert Walker would attempt a flight to Maximum Altitude. Engineers had predicted that the X-15 was capable of reaching 400,000 feet (121,920 meters) but simulations had shown that a safe reentry from that altitude was risky. For this flight, Flight 91, the flight plan called for 360,000 feet (109,728 meters) to give Walker a safety margin. Experience had shown that slight variations in engine thrust and climb angle could cause large overshoots in peak altitude, so this was not considered an excessive safety margin.

For this flight, Joe Walker flew the Number 3 X-15, 56-6672. It was the only one of the three North American Aviation X-15s equipped with the Honeywell MH-96 flight control system, which had been developed to improve control of the rocketplane outside Earth’s atmosphere. This flight was the twenty-second for Number 3.

North American Aviation X-15 56-6672 immediately after being dropped by the Boeing NB-52 Stratofortress. (NASA)
North American Aviation X-15A 56-6672 immediately after being dropped by the Boeing NB-52 Stratofortress. (NASA)

Walker and the X-15 were airdropped from the Boeing NB-52A Stratofortress 52-003, The High and Mighty One, at 45,000 feet (13,716 meters) above Smith Ranch Dry Lake, Nevada, about half-way between the city of Reno and the NASA High Range Tracking Station at Ely. Launch time was 10:05:57.0 a.m., PDT. Walker ignited the Reaction Motors XLR99-RM-1 rocket engine. This engine was rated at 57,000 pounds of thrust. Experience had shown that different engines varied from flight to flight and that atmospheric conditions were a factor. Thrust beyond 60,000 pounds was often seen, but this could not be predicted in advance. The flight plan called for the duration of burn to be 84.5 seconds on this flight. The X-15 climbed at a 45° angle.

As Walker was about to shut down the engine according to plan, it ran out of fuel. The total burn time was 85.8 seconds, just slightly longer than planned.

“At burnout, Joe was passing 176,000 feet [53,645 meters] and traveling at 5,600 feet per second [1,707 meters per second]. He then began the long coast to peak altitude. It would take almost 2 minutes to reach peak altitude after burn out. Two minutes does not seem like a lot of time, but try timing it. Just sit back in your easy chair and count off the seconds. It is almost impossible to believe that you can continue to coast up in altitude for that length of time after the engine burns out. It gives you some feel for how much energy is involved at those speeds. For comparison, when you throw a ball up in the air as hard as you can, it only coasts upward a maximum of 4 or 5 seconds. The X-15 coasted up for 120 seconds.

“The airplane would coast up another 178,000 feet [54,254 meters] during that time to peak out at 354,200 feet. . . .” [107,960 meters]

At The Edge of Space: The X-15 Flight Program, by Milton O. Thompson, Smithsonian Institution Press, Washington, 1992, Chapter 5 at Page 125.

Joe Walker and the X-15 reached the peak of their ballistic trajectory at 354,200 feet (67.083 miles, 107,960 meters). Walker pitched the nose down to be in the proper attitude for atmospheric reentry. The X-15 decelerated as it hit the atmosphere and Walker experienced as much as 7 Gs. The rocketplane’s aerodynamic control surfaces again became operational as it descended through 95,000 feet (28,956 meters) and Walker leveled at 70,000 feet (21,336 meters). He then glided to a landing on Rogers Dry Lake at Edwards Air Force Base, California, after 11 minutes, 8.6 seconds of flight.

Flight 91 was the highest flight achieved by any of the X-15s. It was Joe Walker’s second flight into space. His record would stand for the next 41 years.

© 2016, Bryan R. Swopes

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8 August 1955

8 August 1955: While being carried aloft by a Boeing B-29 Superfortress, the Bell X-1A was being readied for it’s next high-altitude supersonic flight by NACA test pilot Joe Walker. During the countdown, an internal explosion occurred. Walker was not injured and was able to get out. The X-1A was jettisoned. It crashed onto the desert floor and was destroyed.

A number of similar explosions had occurred in the X-1, D-558-II and the X-2. Several aircraft had been damaged or destroyed, and Bell Aircraft test pilot Skip Ziegler was killed when an X-2 exploded during a captive flight. A flight engineer aboard the B-29 mothership was also killed. The B-29 was able to land but was so heavily damaged that it never flew again.

Debris from the X-1A crash site was brought back to Edwards AFB for examination. It was discovered that a gasket material used in the rocket engine fuel systems was reacting with the fuel, resulting in the explosions. The problem was corrected and the mysterious explosions stopped.

Test pilot Joe Walker “horsing around” with the Bell X-1A, 1955. (NASA)

© 2015, Bryan R. Swopes

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4 August 1960

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)

© 2016, Bryan R. Swopes

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19 July 1963

Joe Walker with the Number 2 North American Aviation X-15A, 56-6671, on Rogers Dry Lake. (NASA)
Joseph A. Walker, NASA Chief Research Test Pilot
Joseph A. Walker, NASA Chief Research Test Pilot

19 July 1963: Between 1960 and 1963, NASA Chief Research Test Pilot Joseph Albert Walker made 25 flights in the North American Aviation X-15A hypersonic research rocketplanes. His 24th flight was the 21st for the Number 3 X-15, 56-6672, and the 90th of the X-15 program.

At 10:20:05.0 a.m., Walker and the X-15 were airdropped from the Boeing NB-52B Stratofortress, 53-008, Balls 8, over Smith Ranch Dry Lake, Nevada. Walker fired the Reaction Motors XLR99-RM-1 rocket engine and over the next 84.6 seconds the engine’s 60,000 pounds of thrust drove the X-15 upward. The engine’s thrust on this flight was higher than expected, shutdown was 1.6 seconds late, and Walker’s climb angle was 1½° too high, so the X-15 overshot the predicted maximum altitude and its ballistic arc peaked at 347,800 feet (106,010 meters, 65.8 miles). The maximum speed was Mach 5.50 (3,714 miles per hour, 5,977 kilometers per hour).

Walker glided to a touch down at Rogers Dry Lake, Edwards Air Force Base California, after flying 311 miles in 11 minutes, 24.1 seconds of flight. On this flight, Joe Walker became the first American civilian to fly into Space.

North American Aviation X-15A 56-6672 on Rogers Dry Lake after a flight. (NASA)
North American Aviation X-15A 56-6672 on Rogers Dry Lake after a flight. (NASA)

© 2015, Bryan R. Swopes

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8 June 1966

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. Fuel is spraying out of damaged tanks. (U.S. Air Force)
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.

XB-70A-2 Valkyrie has rolled inverted and pitched nose down. (U.S. Air Force)
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 burnds on the desert floor, north of Barstow, california, 8 June 1968. (U.S. Air Force)
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)

© 2016, Bryan R. Swopes

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