• Military Menu                       

• Introduction
• Systems
• Facilities
• Agencies
• Industry
• Operations
• Countries
• Hot Documents
• News
• Reports
• Policy
• Budget
• Congress
• Links

• WMD
• Intelligence
• Homeland Security
• Space

Boeing 747 Space Shuttle Carrier Aircraft (SCA)

NASA used two modified Boeing 747 jetliners, originally manufactured for commercial use, as Space Shuttle Carrier Aircraft (SCA). One is a 747-100 model, while the other is designated a 747-100SR (short range). NASA chose the 747 as the aircraft to ferry the orbiters between the launch and landing sites, and to other manufacturing and program facilities when overland transportation was unsuitable or unfeasible. The two aircraft are identical in appearance and in their performance as Shuttle Carrier Aircraft. The SCAs are used to ferry space shuttle orbiters from landing sites back to the launch complex at the Kennedy Space Center, and also to and from other locations too distant for the orbiters to be delivered by ground transportation. The orbiters are placed atop the SCAs by Mate-Demate Devices, large gantry-like structures which hoist the orbiters off the ground for post-flight servicing, and then mate them with the SCAs for ferry flights.

NASA 905, the first SCA, was obtained by NASA from American Airlines in 1974. Shortly after acceptance by NASA in 1974, NASA 905 was flown in a series of wake vortex research flights at NASA Dryden in a study to seek ways of reducing turbulence produced by large aircraft. Pilots flying as much as several miles behind large aircraft have encountered wake turbulence that has caused control problems. The NASA study helped the Federal Aviation Administration modify flight procedures for commercial aircraft during airport approaches and departures.

Following the wake vortex studies, NASA 905 was modified by Boeing to its present SCA configuration. A long series of wind tunnel runs had drastic effects on the final 747 Shuttle configuration. First, a large afterbody fairing had to be added to the Shuttle itself to reduce drag and heavy buffeting on the 747 vertical tail. Six tunnels from NASA and more from industry and universities worked on the fairing problem. In addition, two small vertical fins were found necessary on the 747 to provide more directional stability while it was carrying the Shuttle piggyback. The wind tunnel work paid off, for the unpowered landing tests confirmed the performance predictions for the mated vehicles and the crucial separation event. Without thorough testing with models beforehand, two large, expensive craft and their crews would have been in jeopardy from the undefined aerodynamic interference.

The aircraft was returned to Dryden for its role in the 1977 Space Shuttle ALT project. This series of eight captive and five free flights with the orbiter prototype Enterprise, in addition to ground taxi tests, validated the aircraft's performance as an SCA. In addition, the glide and landing characteristics of the orbiter configuration were verified, paving the way for orbital flights. After five years of planning, assembly, and systems testing, the space shuttle approach and landing tests (ALT) began at Dryden. On Feb. 15, 1977, three taxi tests were conducted to validate structural loads and ground-handling and control characteristics of the NASA 747 SCA mated with the prototype orbiter Enterprise. The same modified 747 was also used to carry Enterprise aloft for the ALT program. Following the taxi tests were five captive-carry flights with Enterprise atop the SCA, but without a crew in the prototype orbiter. This series of flights produced important aerodynamic data about the flight characteristics of the mated vehicles during takeoff, climb, cruise and landing. Three captive-carry flights came next, during which crews of astronauts were in the Enterprise cockpit with systems powered up. The five free flights, which began Aug. 12, 1977, and continued through Oct. 26, 1977, verified the orbiter's approach and landing capabilities and demonstrated its subsonic airworthiness.

A crew escape tunnel was installed aboard NASA 747 aircraft number 905 (NASA 905) during the aircraft's modification process for the Shuttle program. The tunnel extended down three decks, from the flight deck to the bottom left side of the fuselage. In a catastrophic emergency, the parachute-clad pilots and flight engineer would activate explosives that would blow a hole through the fuselage for bail-out. Next, they would slide down and out the hole, escaping into the air below the airplane. Activation of the tunnel hole explosives also activated pyrotechnic devices designed to blow out 10 windows above each wing in order to equalize the on-board air pressure allowing the crew to slide down the tunnel. However… this escape system might have led into the inboard engine inlet, obviously not a good thing! The escape tunnel system was removed from the aircraft following completion of the Space Shuttle Approach and Landing Tests (ALT) project.

NASA 905 was the only SCA used by the space shuttle program until Nov. 1990, when NASA 911 was delivered as an SCA. The second SCA aircraft, NASA 911, was a Japan Airlines aircraft acquired by NASA in 1988.