Tag Archives: Boeing NB-52B Stratofortress

9 November 1962

McKAY, John B. (Jack) with X-15 56-6672, 13 March 19649 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.

North American Aviation X-15 56-6671 under the right wing of a B-52 Stratofortress at 45,000 feet. (NASA)
North American Aviation X-15 56-6671 under the right wing of a B-52 Stratofortress at 45,000 feet. (NASA)

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.

A Piasecki H-21 rescue helicopter lands near the overturned X-15 at Mud Lake, 9 November 1961. (NASA)
A Piasecki H-21 rescue helicopter lands near the overturned X-15 at Mud Lake, 9 November 1961. (NASA)
The X-15 rolled over when the left landing skid collapsed because of the high-speed, overweight emergency landing at Mud Lake, Nevada. Jack McKay was trapped in the cockpit and suffered serious spinal injuries. (NASA)
The X-15 rolled over when the left landing skid collapsed because of the high-speed, overweight emergency landing at Mud Lake, Nevada. Jack McKay was trapped in the cockpit and suffered serious spinal injuries. (NASA)
The Number Two X-15, 56-6671, lies upside down and severely damaged at Mud Lake, Nevada, 9 November 1962. (NASA)
The Number Two X-15, 56-6671, lies upside down and severely damaged at Mud Lake, Nevada, 9 November 1962. (NASA)

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.

North American Aviation X-15A-2 56-6671, after a 19-month repair, redesign and modification program. The fuselage was lengthened, additional propellant and reaction control tanks installed internally, the nose wheel and rear landing skid struts lengthened, and external tanks installed. (NASA)
North American Aviation X-15A-2 56-6671, after a 19-month repair, redesign and modification program. The fuselage was lengthened, additional propellant and reaction control tanks installed internally, the nose wheel and rear landing skid struts lengthened, and external tanks installed. (NASA)

© 2016, Bryan R. Swopes

9 November 1961

Major Robert M. White was the first pilot to exceed Mach 4, Mach 5, and on 9 November 1961, he flew to Mach 6.04. (NASA)
Major Robert M. White was the first pilot to exceed Mach 4, Mach 5, and on 9 November 1961, he flew to Mach 6.04. (U.S. Air Force)

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.

Boeing NB-52A Stratofortress 52-003 carries a North American Aviation X-15 piloted by Major Bob White. (NASA)
Boeing NB-52A Stratofortress 52-003 carries a North American Aviation X-15 piloted by Major Bob White. (NASA)

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 number two North American Aviation X-15, 56-6671, is dropped from the Boeing NB-52A Stratofortress, 52-003. The XLR99 rocket engine is just igniting. Frost from the cryogenic fuels coats the fuselage. (NASA)
The number two North American Aviation X-15, 56-6671, is dropped from the Boeing NB-52A Stratofortress, 52-003. The XLR99 rocket engine is just igniting. Frost from the cryogenic fuels coats the fuselage. (NASA)

“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.

North American Aviation X-15 56-6671 accelerates after the XLR99 engine is ignited. (NASA)
North American Aviation X-15 56-6671 accelerates after the XLR99 engine is ignited. (NASA)

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.

The number three North American Aviation X-15 rocketplane, 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. Frost on the X-15's belly shows residual propellants in the tanks. (NASA)
The number three North American Aviation X-15 rocketplane, 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. Frost on the X-15’s belly shows residual propellants in the tanks. (NASA)
NASA ET62-0270
The shattered windshield of X-15 56-6671, 9 November 1961. (NASA)

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.

Major Robert M. White, U.S. Air Force, with one of the three North American Aviation X-15s on Rogers Dry Lake, 1961. (NASA)
Major Robert M. White, U.S. Air Force, with one of the three North American Aviation X-15s on Rogers Dry Lake, 1961. (NASA)

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.

A North American Aviation support crew deactivates X-15 56-6671 on Rogers Dry Lake after a flight, while the mothership, NB-52A Stratofortress 52-003 flies overhead. (NASA)
A North American Aviation support crew deactivates X-15 56-6671 on Rogers Dry Lake after a flight, while the mothership, NB-52A Stratofortress 52-003 flies overhead. (NASA)

© 2016, Bryan R. Swopes

4 November 1960

At the left, Boeing NB-52A 52-003 carries X-15 56-6670 while on the right, NB-52B 52-008 carries X-15 56-6671.(NASA)
At the left, Boeing NB-52A 52-003 carries X-15 56-6670 while on the right, NB-52B 52-008 carries X-15 56-6671. (NASA)

4 November 1960: This photo shows one of the four attempts NASA made at launching two X-15 aircraft in one day. This attempt occurred November 4, 1960.

None of the four attempts was successful, although one of the two aircraft involved in each attempt usually made a research flight.

In this case, Air Force test pilot Major Robert A. Rushworth flew X-15 , 56-6670, on its sixteenth flight to a speed of Mach 1.95 and an altitude of 48,900 feet (14,905 meters).

© 2016, Bryan R. Swopes

16 September 1999

NASA 008, known as “Balls 8,” a modified Boeing RB-52B-10-BO Stratofortress, serial number 52-008, with NASA 824, a Lockheed TF-104G Starfighter, N824NA. The DAST 1 drone is under the bomber’s right wing. (NASA)

16 September 1999: 44 years, 3 months and 6 days after its very first flight, NASA’s airborne launch aircraft, or “mothership,” Balls 8, completed its 1,000th flight.

Balls 8, so-called because of the double zeros in it U.S. Air Force serial number, 52-008, is a Boeing NB-52, modified as a drop ship from its original configuration as an RB-52B-10-BO Stratofortress reconnaissance bomber assigned to the Strategic Air Command. It made its first flight 11 June 1955 and was reassigned from SAC to Edwards Air Force Base to support NASA flight testing operations, 8 June 1959. Balls 8 served NASA until 17 December 2004, when it was replaced by a newer NB-52H Stratofortress.

52-008 was altered at the North American Aviation facility at Air Force Plant 42, Palmdale, California. 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.

The NB-52B was used during the X-15 Program and carried the three hypersonic research aircraft aloft on 159 of their 199 flights. (NB-52A 52-003, The High and Mighty One, made the other 40 launches.) It has also been used to carry the X-24 and HiMat lifting body research aircraft and to launch Pegasus research rockets.

At the time of its retirement, Balls 8 was the oldest B-52 in service, and also the lowest time B-52. It is on display near the north gate at Edwards Air Force Base.

Balls 8, Boeing NB-52B Stratofortress 52-008, as seen from a KC-135A Stratotanker. (NASA)
Balls 8, NASA’s Boeing NB-52B Stratofortress 52-008 “mothership”, as seen from a KC-135A Stratotanker. (NASA)

Of the 744 B-52 Stratofortresses built by Boeing, 50 were B-52Bs and 27 of these were RB-52B reconnaissance bombers.

The airplane was 156 feet, 6.9 inches (47.724 meters) long with a wingspan of 185 feet, 0 inches (56.388 meters) and overall height of 48 feet, 3.6 inches (14.722 meters). The wings were mounted high on the fuselage (“shoulder-mounted”) to provide clearance for the engines which were suspended on pylons. The wings’ leading edges were swept 35°. The bomber’s empty weight was 164,081 pounds (74,226 kilograms), with a combat weight of 272,000 pounds (123,377 kilograms) and a maximum takeoff weight of 420,000 pounds (190,509 kilograms).

Early production B-52Bs were powered by eight Pratt & Whitney J57-P-1W turbojet engines, while later aircraft were equipped with J57-P-19W and J57-P-29W or WA turbojets. The engines were grouped in two-engine pods on four under-wing pylons. The J57 was a two-spool, axial-flow engine with a 16-stage compressor section (9 low- and 7-high-pressure stages) and a 3-stage turbine section (1 high- and 2 low-pressure stages). These engines were rated at 10,500 pounds of thrust (46.71 kilonewtons), each, or 12,100 pounds (53.82 kilonewtons) with water injection.

The B-52B/RB-52B had a cruise speed of 523 miles per hour (842 kilometers per hour). The maximum speed varied with altitude: 630 miles per hour (1,014 kilometers per hour) at 19,800 feet (6,035 meters), 598 miles per hour (962 kilometers per hour) at 35,000 feet (10,668 meters) and 571 miles per hour (919 kilometers per hour) at 45,750 feet (13,945 meters). The service ceiling at combat weight was 47,300 feet (14,417 meters).

Maximum ferry range was 7,343 miles (11,817 kilometers). With a 10,000 pound (4,536 kilogram) bomb load, the B-52B had a combat radius of 3,590 miles (5,778 kilometers). With inflight refueling, the range was essentially world-wide.

This "score board" painted on the side of Balls 8 shows many of the missions that it flew as a "mothership" for NASA. (NASA)
This “score board” painted on the side of Balls 8 shows many of the missions that it flew as a “mothership” for NASA. (NASA)

Defensive armament consisted of four Browning Aircraft Machine Guns, Caliber .50, AN-M3, mounted in a tail turret with 600 rounds of ammunition per gun. These guns had a combined rate of fire in excess of 4,000 rounds per minute. (Eighteen RB-52Bs were equipped with two M24A1 20 mm autocannon in the tail turret in place of the standard four .50-caliber machine guns.)

The B-52B’s maximum bomb load was 43,000 pounds (19,505 kilograms). It could carry a 15-megaton Mark 17 thermonuclear bomb, or two Mark 15s, each with a maximum yield of 3.8 megatons.

Balls 8 lands on a runway marked on Rogers Dry Lake at Edwards Air Force Base, California. The drogue parachute helps to slow the airplane. (NASA)
Balls 8 lands on a runway marked on Rogers Dry Lake at Edwards Air Force Base, California. The drogue parachute helps to slow the airplane. (NASA)

© 2017, Bryan R. Swopes

27 June 1963

27 June 1963: At 09:56:03.0 PDT, Major Robert A. Rushworth, United States Air Force, flying the Number Three North American Aviation X-15 research rocketplane, 56-6672, was air-dropped from the NB-52B Stratofortress mothership, Balls 8, over Delamar Dry Lake in Nevada.

This was the 87th flight of the X-15 Program, and Bob Rushworth’s 14th.

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

Rushworth fired the Reaction Motors XLR99-RM-1 engine for 80.1 seconds and accelerated to Mach 4.89 (3,425 miles per hour, 5,512 kilometers per hour). The X-15 climbed to an altitude of 285,000 feet (86,868 meters, 53.98 miles). Rushworth touched down at Edwards Air Force Base after 10 minutes, 28.0 seconds of flight.

Major Rushworth qualified for Astronaut wings on this flight, the second X-15 pilot to do so.

From 1960 and 1966, Bob Rushworth made 34 flights in the three X-15s, more than any other pilot.

Command Pilot Astronaut insignia, United States Air Force
Command Pilot Astronaut insignia, United States Air Force

© 2015, Bryan R. Swopes