Boeing NB-52A 52-003 with a North American Aviation X-15 under its right wing, at Edwards Air Force Base, 31 December 1961. (NASA)
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.
The X-15 was attached to this underwing pylon by three remotely-actuated standard Air Force bomb shackles. (NASA)To allow clearance for the X-15’s vertical fin, a notch had to be cut in the trailing edge of the inboard right flap. (NASA)
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.
NB-52 liquid oxygen panel. (NASA)
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.
A North American Aviation F-100F Super Sabre chase plane checks an X-15 as its APUs are activated just prior to being released from NB-52A 52-003. (NASA)
Boeing NB-52B Stratofortress 52-008, Balls 8, escorted by two NASA F-18 chase planes, performs a farewell flyover during its final flight, 16 November 2004. (NASA)
16 November 2004: Balls 8, the Boeing NB-52B “mothership” at the NASA Dryden Flight Research Center (located at Edwards Air Force Base, California) performs a farewell flyover during its final flight. 52-008 was both the oldest airplane in the U.S. Air Force inventory and the lowest time B-52 Stratofortress still operational.
Boeing RB-52B-10-BO Stratofortress 52-008 was built at Seattle, Washington and made its first flight 11 June 1955. It was turned over to NASA 8 June 1959 for use as a air launch vehicle for the X-15 rocketplane. North American Aviation modified the bomber for its new role at Air Force Plant 42, Palmdale, California. It was redesignated NB-52B.
NASA 008, known as “Balls 8”, a modified Boeing RB-52-10-BO Stratofortress, 52-008, with NASA 824, a Lockheed TF-104G Starfighter, N824NA. (NASA)
52-008 carried an X-15 for the first time 23 January 1960. Sharing the mothership responsibilities with the earlier NB-52A 52-003, Balls 8 carried the X-15s aloft on 159 flights, dropping them 106 times.
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)A visual reminder of the missions flown by “mothership” Balls 8. (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 #1, 56-6670, on its sixteenth flight to a speed of Mach 1.95 and an altitude of 48,900 feet (14,905 meters).
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, 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)
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)
William Barton Bridgeman (Boris Artzybasheff/TIME Magazine)
15 August 1951: Just 8 days after he set an unofficial world speed record of Mach 1.88 (1,245 miles per hour; 2,033.63 kilometers per hour), Douglas Aircraft Company test pilot William Barton (“Bill”) Bridgeman flew the rocket-powered United States Navy/National Advisory Committee on Aeronautics (NACA) Douglas D-558-II Skyrocket, Bu. No. 37974, to a world record altitude at Edwards Air Force Base in the high desert of Southern California.
The Skyrocket was airdropped at 34,000 feet (10,363 meters) from a highly-modified U.S. Navy P2B-1S Superfortress, Bu. No. 84029. The mother ship was a U.S. Air Force Boeing B-29-95-BW Superfortress, 45-21787, transferred to the Navy and flown by another Douglas test pilot, George R. Jansen.
Douglas D-558-II Skyrocket, Bu. No., 37974, NACA 144, is dropped from the Boeing P2B-1S Superfortress, Bu. No. 84029, NACA 137. (NASA)
The flight plan was for Bridgeman to fire the rocket engine and allow the Skyrocket to accelerate to 0.85 Mach while climbing. The Skyrocket was powered by a Reaction Motors LR8-RM-6 engine, which produced 6,000 pounds of thrust. As the rocketplane continued to accelerate to Mach 1.12, the test pilot was to pull up, increasing the angle of climb while holding an acceleration rate of 1.2 Gs. This would result in a constantly increasing angle of climb. When it reached 50°, Bridgeman was to maintain that, climbing and accelerating, until the rocket engine ran out of fuel.
Initially, the plan was to continue climbing after engine shutdown until the D-558-II was approaching stall at the highest altitude it could reach while on a ballistic trajectory. There were differing expert opinions as to how it would behave in the ever thinner atmosphere. On the morning of the flight, Douglas’ Chief Engineer, Ed Heinemann, ordered that Bridgeman push over immediately when the engine stopped.
Bill Bridgeman stuck to the engineers’ flight plan. As the Skyrocket accelerated through 63,000 feet (19,200 meters), it started to roll to the left. He countered with aileron input, but control was diminishing in the thin air. The next time it began there was no response to the ailerons. Bridgeman found that he had to lower the Skyrocket’s nose until it responded, then he was able to increase the pitch angle again. At 70,000 feet (21,336 meters), travelling Mach 1.4, he decided he had to decrease the pitch angle or lose control. Finally at 76,000 feet (23,165 meters), the engine stopped. Following Heinemann’s order, Bridgeman pushed the nose down and the D-558-II went over the top of its arc at just 0.5 G.
Bill Bridgeman. (Unattributed)
“In the arc she picks up a couple of thousand feet. The altimeter stops its steady reeling and swings sickly around 80,000 feet. The altitude is too extreme for the instrument to function.
“Eighty thousand feet. It is intensely bright outside; the contrast of the dark shadows in the cockpit is extreme and strange. It is so dark lower in the cockpit that I cannot read the instruments sunk low on the panel. The dials on top, in the light, are vividly apparent. There seems to be no reflection. It is all black or white, apparent or non-apparent. No half-tones. It is a pure, immaculate world here.
“She levels off silently. I roll right and there it is. Out of the tiny windows slits there is the earth, wiped clean of civilization, a vast relief map with papier-mâché mountains and mirrored lakes and seas. . . .
“It is as if I am the only living thing connected to this totally strange, uninhabited planet 15 miles below me. The plane that carries me and I are one and alone.”
—The Lonely Sky,William Bridgeman with Jacqueline Hazard, Castle and Company LTD, London, 1956, Chapter XXII at Page 268.
After the data was analyzed, it was determined that William Bridgeman and the Douglas Skyrocket had climbed to 79,494 feet (24,230 meters), higher than any man had gone before. This was the last flight that would be made with a Douglas test pilot. The rocketplane was turned over to NACA, which would assign it the number NACA 144.
A Douglas D-558-II Skyrocket, Bu. No. 37974, glides back toward Rogers Dry Lake at Edwards Air Force Base. A North American Aviation F-86E-1-NA Sabre, 50-606, flies chase. Lieutenant Colonel Frank K. “Pete” Everest and Major Charles E. “Chuck” Yeager frequently flew as chase pilots for both Bill Bridgeman and Scott Crossfield. (NASA)
Bill Bridgeman had been a Naval Aviator during World War II, flying the Consolidated PBY Catalina and PB4Y (B-24) Liberator long range bombers with Bombing Squadron 109 (VB-109), “The Reluctant Raiders.” Bridgeman stayed in the Navy for two years after the war, then he flew for Trans-Pacific Air Lines in the Hawaiian Islands and Pacific Southwest Airlines in San Francisco, before joining Douglas Aircraft Co. as a production test pilot, testing new AD Skyraiders as they came off the assembly line at El Segundo, California. He soon was asked to take over test flying the D-558-2 Skyrocket test program at Muroc Air Force Base.
The D-558-II Skyrocket was Phase II of a planned three phase experimental flight program. It was designed to investigate flight in the transonic and supersonic range. It was 46 feet, 9 inches (14.249 meters) long with a 25 foot (7.62 meter) wing span. The wings were swept back to a 35° angle. The Skyrocket was powered by a Westinghouse J34-WE-40 11-stage axial-flow turbojet engine, producing 3,000 pounds of thrust, and a Reaction Motors LR8-RM-6 four-chamber rocket engine, which produced 6,000 pounds of thrust. The rocket engine burned alcohol and liquid oxygen.
There were three D-558-2 Skyrockets. Between 4 February 1948 and 28 August 1956, they made a total of 313 flights. Bill Bridgeman’s speed and altitude record-setting Skyrocket, Bu. No. 37974, NACA 144, is in the collection of the Smithsonian Institution National Air and Space Museum.
Douglas D-558-2 Skyrocket, Bu. No. 37974, NACA 144. (NASA)
