From the Orbiter’s first drop tests flights to its inspirational roll as a historical landmark, the Shuttle Carrier Aircraft is an integral part of the Shuttle’s history. NASA used two modified Boeing 747 jetliners, originally manufactured for commercial use, as Space Shuttle Carrier Aircraft, NASA 905 and NASA 911. The two aircraft are identical in appearance and in their performance as Shuttle Carrier Aircraft (SCA). In the Fall of 2015, NASA 905 will go on permanent display at Space Center Houston. The display will feature a full scale orbiter replica installed in the transit position on top.
NASA 905 was the first SCA. It was obtained from American Airlines in 1974. Shortly after acceptance by NASA, the SCA flew a series of wake vortex research flights at the Dryden Flight Research Center, Edwards, Calif., 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 and the aircraft was returned to Dryden for its role in the 1977 Space Shuttle Approach and Landing Tests (ALT). 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 to verifying the glide and landing characteristics of the orbiter configuration – paving the way for orbital flights.
A flight crew escape system, consisting of an exit tunnel extending from the flight deck to a hatch in the bottom of the fuselage, was installed during the modifications. The system also included pyrotechnics to activate the hatch release and cabin window release mechanisms. The flight crew escape system was removed from the NASA 905 following the successful completion of the ALT program.
NASA 905 was the only SCA used by the space shuttle program until November 1990, when NASA 911 was delivered as an SCA. Along with ferrying Enterprise and the flight-rated shuttle orbiters between the launch and landing sites and other locations, NASA 905 also ferried Enterprise to Europe for display in England and at the Paris Air Show.
Features that distinguish the two SCAs from standard 747 jetliners are:
- Three struts with associated interior structural strengthening protrude from the top of the fuselage (two aft, one forward) on which the orbiter is attached.
- Two additional vertical stabilizers, one on each end of the standard horizontal stabilizer, to enhance directional stability.
- Removal of all interior furnishings and equipment aft of the forward No. 1 doors.
- Instrumentation used by SCA flight crews and engineers to monitor orbiter electrical loads during the ferry flights and also during pre- and post-ferry flight operations.
During its 42-year flight career, both as a commercial jetliner and as a NASA space shuttle carrier, SCA 905 amassed 11,017 flight hours and made 6,334 takeoffs and landings.