When it came to transporting its space shuttles, NASA faced a unique challenge: finding an aircraft capable of carrying the hefty payload of approximately 100 tons. The agency evaluated two contenders for the job: the massive Lockheed C-5 Galaxy and the Boeing 747. Ultimately, NASA opted for the 747, primarily due to its design advantages and powerful performance.
The Boeing 747 features a low-wing airframe, which provided a stable and effective platform for mounting the shuttle. In contrast, the C-5’s high-wing design could have posed difficulties in securely attaching the shuttle. The selection of the 747 was also influenced by its powerful four-engine configuration. Introduced into commercial service in 1969, the 747 was the largest commercial jet at the time of its maiden flight, and it remains one of Boeing’s most celebrated aircraft.
Each of the four Pratt & Whitney engines on the 747 delivers an impressive 48,600 pounds of thrust. This capability allows the aircraft to manage a maximum gross taxi weight of up to 713,000 pounds. The specific 747 model selected for this task was not lightweight itself, weighing over 300,000 pounds when empty. NASA modified two 747s for shuttle transport: the first, designated NASA 905, was a Boeing 747-123 model acquired from American Airlines in 1974 for approximately $15.6 million. A second aircraft, a 747-100SR-46 from Japan Air Lines, joined the fleet in 1989 and was named NASA 911.
Both aircraft underwent significant transformations to adapt them for their new role. Boeing reinforced the fuselage with three robust struts to secure the shuttle. This modification required substantial internal structural fortification. Additionally, the aerodynamics of the aircraft were affected by the shuttle’s weight and shape. To counter this, engineers installed two extra vertical stabilizers on the tail fins to enhance directional stability.
The orbiter’s delicate thermal protection tiles necessitated careful engineering to minimize aerodynamic resistance. Instrumentation was also added to monitor the orbiter’s electrical loads during flight. For initial tests in 1977, NASA 905 even featured an elaborate crew escape system that utilized pyrotechnics.
The process of attaching the shuttle to the aircraft involved complex machinery known as Mate-Demate Devices. These structures would lift the shuttle high enough for the 747 to be driven underneath and securely attached. NASA 905 operated solo for over a decade before NASA 911 joined the mission in late 1990, sharing the shuttle transport responsibilities thereafter.
Following the retirement of the shuttle fleet, both aircraft had one final mission. NASA 905 completed three last ferry flights, transporting the orbiters to their final resting places in museums. Notably, it delivered the Discovery orbiter to the Smithsonian National Air and Space Museum, completing a celebratory loop around Washington, D.C., at an altitude of about 1,500 feet. NASA 911 was retired in February 2012 and is now on display at the Joe Davies Heritage Airpark, while NASA 905 retired later that year to become part of a major exhibit at Space Center Houston.
NASA’s decision to employ the Boeing 747 for shuttle transport not only showcased the aircraft’s engineering capabilities but also highlighted the agency’s commitment to innovation in space exploration logistics. This collaboration between aerospace engineering and space travel remains a significant chapter in the history of human spaceflight.
