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NB-52A and NB-52B Stratofortress Launch Platforms - X-15

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More information about the history of the X-15 program can be found on the X-15 Forty-Seven Years Later pages.

There is a venerable bird flying at the NASA Dryden Flight Research Center at Edwards AFB. The oldest flying B-52 is currently engaged in the testing of the Space Station Crew Return Vehicle demonstrator, the X-38, and will soon be launching the unmanned, air-breathing, Mach-8 Hyper-X, mounted on the nose of a Pegasus satellite launcher. In its long career, it has launched the three X-15 hypersonic rocket planes, the HL-10, M2-F2/F3, X-24A/B lifting bodies, the space shuttle booster parachute recovery system testbed, a 3/8 scale F-15 remotely piloted research vehicle (RPRV), the High Maneuverability Aircraft Technology (HiMAT) RPRV, the Pegasus satellite launcher, and tested the drogue chute currently used on the space shuttle orbiters.

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By the time the X-15 was developed in the latter half of the fifties, the air launching of high speed rocket propelled research vehicles had become standard practice.

 Initially the intent was to procure a surplus B-36 Peacemaker and mount the X-15 in the bomb bay as the X-1 and X-2 vehicles had been mounted in B-29 and B-50 Superfortresses. Diagram courtesy AFFTC/HO.

When early production B-52s had completed their initial service tests and became available for other uses, the benefits of using a Stratofortress were quickly realized. The third B-52A and the fifth B-52B were sent to North American for modification as launch aircraft for the X-15 program.

Modifications to the two aircraft were made at Plant 42 in Palmdale. The B-52A, serial 52-0003, arrived at Plant 42 from Boeing on November 29, 1957 and was moved into the North American hangar for the beginning of modifications on February 4, 1958. The B-52B, serial 52-0008, arrived on December 13, 1958 and was moved into the North American hangar on January 6, 1959.

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NB-52B, Serial 52-0008, with the X-15 #1 Serial 56-6670 at the 1960 Edwards AFB Open House on May 17.	The North American X-15-2 Serial 56-6671, making its first public appearance, poses with the Boeing NB-52A Stratofortress, serial 52-0003, launch aircraft at the May 19, 1959 Edwards Air Force Base Open House.

The modifications included a pylon under the starboard wing, inboard of the engine nacelles and capable of carrying 50,000 pounds. The pylon provided three shackles for the support of the X-15 and umbilical attachments for Liquid Oxygen, nitrogen, breathing oxygen and electrical power. The No. 3 main fuel tank located in the wing above the pylon was removed.

To accommodate the vertical stabilizer of the X-15, a notch was cut into the trailing edge of the starboard wing directly behind the X-15 pylon. The inboard flaps were disabled, but the outer flaps remained functional. A 1,500 gallon liquid oxygen tank was installed in the bomb bay of each B-52 to refill the X-15's tanks as the volatile fluid boiled away while the X-15 was being carried to the launch altitude of 45,000 feet. Closed circuit television, film motion picture cameras, and lights were installed on the starboard side of the fuselage. Tail gun turrets and tip tanks were removed.

A launch panel was installed on the upper deck of the B-52, at which the operator could monitor the fueling and other services of the X-15. Through the launch panel, altitude and velocity data were fed into the X-15 inertial guidance computer until launch. The launch panel operator watched for the liquid oxygen top-off overflow and checked the function of the X-15 flight control surfaces. Later in the program, a plexiglas dome was mounted on the upper deck of each B-52 for direct observation of the X-15 by the launch panel operator. The release system for the X-15 was installed for operation by the pilot of the B-52.

A panel of five launch indicator lights was installed to coordinate the pilots of the B-52 and X-15. Three lights confirmed the pylon hooks have securely engaged the X-15. The "ready to launch" light and the "launch" light were operated by switches in the cockpit of the X-15 to indicate, first, that the its systems had been configured for launch and, second, that the X-15 pilot was ready to begin the launch countdown. This was installed as a precaution after a couple of incidents in earlier rocket programs when pilots had been inadvertently launched after they had tried to abort the mission.

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The X-15 #2, serial 56-6671, was on display on the left side of the NB-52B	The NB-52A, Serial 52-0003, taxis along the flightline. The NB-52A carried the name "The High and Mighty One" and nose art depicting an eagle dropping an X-15 from its talons.
The dayglo had been stripped from the engine inlets and tail of the NB-52A when this picture was taken.

The modifications were tested by Captains Charles Bock and John Allavie with W. Berkowitz of North American at the launch panel. Initially, airspeed was limited to 500 miles per hour with the X-15 attached.

 Joe Walker had made the first mach 3 X-15 flight in it on May 12. He reached mach 3.11 (2111 miles per hour) and an altitude of 77,882 feet, breaking Mel Apt's speed record of mach 3.196 (2094 miles per hour), set in the X-2 on September 27, 1956. Photo by Richard Lockett Sr.

Two days after the airshow, the X-15 #1 would be flown by Major Robert White to a speed of mach 2.31 (1590 miles per hour) and an altitude of 108,997 feet, an altitude only previously exceeded by Ivan Kinchloe in the X-2 on September 7, 1956.

The orange dayglo paint on the tail can be seen to be peeling and within a short time it was removed, along with the dayglo on the engine intakes. Dayglo was used extensively on the aircraft operated from Edwards AFB in that era because orange wreckage is much easier to spot in the desert than aluminum, which tends to mirror the color of its surroundings.

  Major Allavie and Captain Campbell would drop Major Bob Rushworth in the X-15 #1 on its twenty-eighth flight on May 22. Using the 50,000 pound thrust XLR-99 rocket engine, the X-15 would reach mach 5.03 (3450 miles per hour) and 100,400 feet altitude on that flight. Photo by Tom Brewer via Greg Spahr.

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The NB52-A recently returned from modifications at Boeing in Wichita, Kansas

 All three X-15s would launched from the NB-52B before the next launch from the NB-52A occurred on June 16. Lt. Colonel Fitzhugh Fulton and Squadron Leader Cratney would launch Captain Joe Engle on the X-15 #3's forty-third flight. Engle would attain mach 4.69 (3404 miles per hour) and an altitude of 244,700 feet.. Photo by Tom Brewer via Greg Spahr.

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X-15A-2

 The X-15#2 was involved in a serious accident on its thirty-first flight on November 9, 1962. While it was being repaired, the opportunity was taken to modify it for even higher speeds and it was re-designated as the X-15A-2. The most notable modification was the addition of large external fuel and oxidizer tanks. The fuselage was stretched by twenty-nine inches. The windshield was replaced with smaller oval windows to reduce the potential for cracking that had been displayed by the original. It is seen here mounted on the NB-52B on the flightline at Edwards AFB in late 1965 or 1966. Photo courtesy North American Rockwell.

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NB-52B

On May 8, 1967 the NB-52B had launched Bruce Peterson at the controls of the sixteenth glide flight of the M2-F2. Roll instability and a rescue helicopter in Peterson's flight path caused him to land before the landing gear had fully extended, resulting in a spectacular rolling, flipping crash. Bruce Peterson was badly injured in the accident, film of which was used in the opening sequence of "The Six Million Dollar Man" television series. Photo by Paul Minert via Greg Spahr.

The X-15 #1's next flight was its seventy-second flight on June 15. Colonel Cotton and Major Reschke would launch Mike Adams from the NB-52A on a flight that would attain mach 5.44 (3693 miles per hour) and an altitude of 229,300 feet.

The next launch conducted by the NB-52B would be the sixtieth flight of the X-15 #3, serial 56-6672, on June 22. Lt. Colonel Sturmthal and Colonel Cotton would launch Bill Dana on a flight to mach 5.44 (3611 miles per hour) and an altitude of 82,200 feet.

 

The All-up flight, October 3, 1967

 

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X-15A-2

The X-15A-2, piloted by Pete Knight , shortly after launch on mission 2-53-97. It had been launched from the NB-52B by Colonel Cotton and Major Reschke over Mud Lake in Nevada at an altitude of 45,000 feet. On this flight it achieved the highest speed of any manned aircraft except the space shuttle, mach 6.70 (4520 miles per hour). It flew nearly directly over Racetrack Playa in Death Valley National Monument at about 100,000 feet going mach 6. If you had been in Death Valley on that October morning, the rocket plume of the hypersonic Spaceplane would have been clearly visible as it streaked across the sky, twice as fast as an SR-71A Blackbird. Shortly afterward, the sonic boom would have echoed back and forth within the valley walls. (Photo courtesy Edwards Air Force Base History Office)

As the X-15A-2 crossed Death Valley, shock waves streaming from the supersonic combustion ramjet aerodynamic test shape mounted on the ventral stabilizer superimposed themselves in unexpected ways, creating hot spots at the intersections of the waves. Higher temperatures on the ventral fin were encountered than had been predicted. Holes were burnt through the nickel-iron skin and plasma flowed into the stabilizer and the rear fuselage of the X-15A-2 causing significant damage to the plumbing and wiring within.

The X-15A-2 was subsequently repaired, but it never flew again.

 

Mike Adams crash in the X-15-3, November 15, 1967

 

Mike Adams' seventh flight in the X-15 was the one hundred ninety-first flight of the program. He flew the third X-15, serial 56-6672, which had been equipped with the MH-96 flight control system that automatically blended the aerodynamic flight controls with the hydrogen peroxide fueled reaction control thrusters as the X-15 transitioned from the atmosphere to the vacuum of space and then re-entered the atmosphere.

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Mike Adams

Mike Adams  is seen here standing in front of the modified X-15A-2, serial 56-6671, in the NASA Flight Research Center Hangar at Edwards Air Force Base. (Photo courtesy North American Rockwell)

The X-15 carried seven experiments; a boost guidance experiment, a solar spectrum measurement, an ultraviolet rocket exhaust plume detector, a micrometeorite collector, a tip pod deflection camera, Saturn rocket booster ablative thermal protection material, and a "traversing probe" for measuring the shock wave in front of the wing tip pod. These experiments added to the workload of the X-15 pilot. The solar spectrum measurement required the pilot to extend it from the q-bay behind the cockpit and then retract it again. The ultraviolet plume detector would observe the X-15 rocket exhaust plume against black space and then against the earth as a background which required the X-15 to be rolled from side-to-side,

Mike Adams was launched at 10:30 in the morning in the X-15 #3, over Delamar Dry Lake in Nevada from the modified NB-52B, serial 52-0008, at an altitude of 45,000 feet. He fired the 55,000 pound thrust XLR-99 rocket engine and accelerated for 82 seconds to over mach 5. After the fuel was expended the X-15 continued on a ballistic trajectory to 266,000 feet, three minutes after launch.

An electrical disturbance from the traversing probe experiment caused the automatic reaction control thrusters to shut down. It also caused errors in the presentation of the attitude of the X-15 on the cockpit displays. The thrusters should have kept the X-15 aligned with its flight path. Their deactivation allowed the nose of the spaceplane to swing to one side as it reached its peak altitude.

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The X-15 #3 rides under the wing of the NB-52B, serial 52-0008, prior to launch in early 1967.

Twice during the ascent, the inertial computer system failure lights came on. Then an electrical disturbance disengaged the pitch and roll stability dampers. Five seconds later the dampers reengaged.

As he started to descend, Adams began to use the manual reaction controls. It is believed that he was suffering from vertigo, a loss of spatial orientation. His control inputs were in the wrong direction and made the X-15 swing even farther around. The X-15 spun completely around at 3,500 miles per hour as it re-entered the atmosphere over Cuddeback Lake near the gold mining town of Randsburg in California.

As the X-15 descended through 120,000 feet, the X-15 recovered from the spin, but at that point the adaptive flight control system over controlled the elevators, commanding them to move faster than the actuators could move them. This drove the X-15 into violent pitch and roll oscillations. Mike Adams was tossed up and down inside the cockpit of the X-15 with thirteen times the force of gravity, both ways. He was unable to initiate the ejection sequence. The g-load on the X-15 caused its nickel-steel structure to break into many pieces at about 60,000 feet.

Mike Adams was killed when the cockpit section of the X-15 hit the ground near the town of Johannesburg in the Mojave Desert, five minutes and fifty seconds after he had been launched from the NB-52B. He was posthumously awarded astronaut's wings.

The loss of Mike Adams is not often enough noted in the recounting of the story of the conquest of space.

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The NB-52A in storage at MASDC on April 24, 1971.

The full story of the X-15 program is found in Milton Thompson's book, At the Edge of Space: The X-15 Flight Program, which was the source of the information found on this page.

The last X-15 launch from the NB-52B was the seventy-seventh flight of the X-15 #1 on May 11, 1968. Bill Dana was launched by Lt. Colonel Reschke and Colonel Cotton.

The last X-15 flight was made by Bill Dana in the X-15 #1 on October 24, 1968. The X-15 reached mach 5.38 (3716 miles per hour) and an altitude of 255,000 feet. He was launched by Lt. Colonel Sturmthal and Squadron Leader Miller from the NB-52A. It was the eighty-first flight of the X-15 #1 and the one hundred-ninety-ninth flight of the program. The NB-52A made one more captive carry of the X-15 #1 on December 12, but that flight was aborted.

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Back at MASDC, the NB-52A sat unused.

The maximum speed attained during the X-15 program was mach 6.70 (4520 miles per hour) on the fifty-third and last flight of the X-15A-2 on October 3, 1967 with Captain Pete Knight at the controls. He had been launched from the NB-52B by Colonel Cotton and Major Reschke.

The maximum altitude of the program was 354,200 feet, achieved during the twenty-second flight of the X-15 #3. Joe Walker flew that X-15 flight after being launched by Major Bement and Lt. Colonel Lewis from the NB-52A on August 22, 1963.