The B-52 that launched a thousand ships.
- By Preston Lerner
- Air & Space magazine, July 2001
(Page 2 of 3)
The mothership concept isn’t unique to big, old bombers and Edwards Air Force Base. Parasite airplanes were fitted to larger aircraft and airships as far back as the 1920s, and NASA uses two modified Boeing 747s to ferry space shuttles from coast to coast. (The Soviets carried their Buran shuttle on an Antonov An-225.) But the modern air launch concept was hatched for the Bell X-1’s assault on the sound barrier in the late 1940s, and it was perfected on the desolate dry lakes of the Mojave Desert.
Because the rocket planes of the 1940s and ’50s had such limited fuel capacity, they were carried aloft by B-29s and B-50s and dropped from the bomb bays (see In the Museum, p. 14). But the X-15 was significantly larger and heavier than earlier rocket planes. A more substantial mothership was required, and the obvious choice was Boeing’s new B-52 Stratofortress. Designed to deliver nuclear weapons to every corner of the globe, the Buff—an acronym for Big Ugly Fat Fellow (or something like that)—would have no problem lifting a 50,000-pound payload.
Double-oh-eight—that is, the eighth production Buff—was delivered to Edwards in 1955. Originally designated an RB-52B reconnaissance/bomber, the airplane was used to test bomb navigation systems until it was selected for the North American Aviation X-15 program. In 1958, it was sent to the North American plant in nearby Palmdale, where a pylon equipped with a heavy-duty hook assembly was mounted underneath the right wing, between the fuselage and inboard engines. The structural support for the pylon and the supporting systems forced the removal of one of four main fuel tanks, two of four ancillary tanks, and both external drop tanks. Also, a notch had to be cut in the right flap to accommodate the tail of the X-15.
The first X-15 air launch was performed by 008’s sister mothership, an A model B-52 known as 003. Double-oh-eight got into the act on January 23, 1960, when Air Force Major Fitz Fulton flipped the switch that opened the hooks suspending the X-15 from the pylon of the B-52 and North American test pilot Scott Crossfield lit the eight chambers of his XLR-11 rocket engines while crooning “Back in the Saddle Again” over the radio. During the eight-year program, 003 and 008 performed 199 launches, typically at Mach 0.82 and 45,000 feet, with the X-15 maxing out at 53,100 pounds. Yet the Buffs got little of the glory and produced none of the drama associated with the high-profile, high-speed, high-altitude program. “Very rarely has a mission been aborted because of the B-52,” says Bill Albrecht, a one-time X-15 engineer who continues to ride herd on 008 as Dryden’s assistant director of operations. “When it’s been called on, it’s been there.”
As befits a leviathan with a wingspan so broad—185 feet—that the wings are fitted with outriggers, 008 handles like an oceanliner. To compensate for the asymmetrical load produced by an object attached to the pylon, the fuel cells are filled—or partly filled, as the case may be—to balance the airplane, and the copilot adjusts the fuel flow from tank to tank during flight to keep the Buff properly trimmed. “When we dropped the X-15, the airplane would roll about 15 or 20 degrees, but it was easily controlled with the aileron,” says Fulton, who first flew the XB-52 in 1953 and was still flying 008 when he retired from NASA in 1986. “It was just like dropping a big bomb.”
The trickiest aspect of flying 008 stems from the fact that flaps, which extend the wing area and allow controllable flight at slower speeds, aren’t used because the inboard right flap had to be mutilated to accommodate the X-15. “An operational B-52 won’t take off without flaps,” Fullerton says. “And technically, a no-flaps landing is considered an emergency.” While standard Buffs take off in a level attitude, 008’s nose gear has to be yanked off the runway and the airplane takes off nose-up. Landings are hot—at least 35 mph faster than with full flaps—and the pilot can’t do much to prevent the airplane from slamming down on the nose gear after the rear trucks hit the runway. “At times,” Fullerton admits, “landings can be teeth-jarring.”
After the final X-15 flight, in 1968, 003 was retired, eventually finding a home in the Pima County Air Museum in Tucson. But 008 continued to serve as the mothership for the lifting body program. When the last of those wingless wonders flew in 1975, the Air Force planned to put 008 out to pasture. But NASA still had some use for the airplane, so in 1976 a loan agreement was negotiated, and 008 went back to work.
Since then, 008 has been the biggest component of myriad programs studying everything from high angles of attack to atmospheric conditions. Some, such as tests of the space shuttle drag chute, required only eight flights. Tests of the F-111 crew escape module, on the other hand, extended over parts of two decades. But it was a program to develop the parachute recovery system for the shuttle’s solid rocket boosters that gave 008 the sportiest moment in its career. The hooks failed to open fully during a test flight, leaving a 50,000-pound dummy cylinder with a parachute on one end only partially attached to the pylon. When Fitz Fulton couldn’t shake it loose, he returned to Edwards—avoiding populated areas—and carefully set the airplane down, going easy on the brakes to avoid any damage from the loose payload.