When NASA required a transport solution for its space shuttles, each weighing approximately 100 tons, the agency turned to aviation giants. After evaluating two primary candidates, the robust Lockheed C-5 Galaxy and the iconic Boeing 747, NASA ultimately selected the latter, citing its superior design and performance capabilities.
The decision to use the Boeing 747 stemmed from its airframe design, which positioned the wings below the main fuselage. This layout provided a more stable platform for mounting the space shuttle compared to the C-5’s high-wing configuration, which posed challenges for such an operation. Additionally, the 747 was a modern four-engine jumbo jet that had just entered commercial service in 1969, boasting significant power and efficiency.
Equipped with four Pratt & Whitney engines, each generating up to 48,600 pounds of thrust, the Boeing 747 could handle a maximum gross taxi weight of 713,000 pounds. The aircraft selected for NASA’s project was no lightweight itself, exceeding 300,000 pounds when empty. In total, NASA modified two Boeing 747s specifically for the shuttle transport role.
Transformations for Shuttle Transport
The first aircraft, designated NASA 905, was a Boeing 747-123 model acquired from American Airlines in March 1974 for approximately $15.6 million. A second aircraft, NASA 911, was acquired in 1989, a 747-100SR-46 from Japan Air Lines. Both planes underwent extensive modifications to accommodate the shuttle’s unique requirements.
Boeing engineers installed three massive struts to the fuselage to securely hold the shuttle. This necessary structural enhancement also required significant internal strengthening to support the added weight and aerodynamic changes. To counteract the negative effects on flight dynamics caused by strapping the shuttle on top, engineers attached two additional vertical stabilizers to the tail fins, improving directional stability during flight.
Specialized instrumentation was incorporated to monitor the orbiter’s electrical loads while airborne. For initial tests in 1977, NASA 905 even featured a remarkable crew escape system utilizing pyrotechnics to ensure safety during flights.
Getting the shuttle onto the 747 was a complex operation involving large structures known as Mate-Demate Devices. These devices hoisted the orbiter high above the ground, allowing the 747 to be driven underneath for attachment.
Operational Legacy and Retirement
NASA 905 operated solo for over a decade, transporting shuttles on numerous missions. In late 1990, NASA 911 joined the fleet, and the two jets shared the transport duties until the shuttle program concluded. Following the retirement of the shuttle fleet, both aircraft had one final responsibility: transporting the orbiters to their respective museum homes.
NASA 905 famously delivered the Discovery orbiter to the Smithsonian’s National Air and Space Museum, completing a celebratory loop around Washington, D.C., at an altitude of approximately 1,500 feet. The NASA 911 was officially retired in February 2012 and is currently on display at the Joe Davies Heritage Airpark. NASA 905 retired later that same year and became a centerpiece of an exhibit at Space Center Houston, ensuring the legacy of these remarkable aircraft continues to inspire future generations.
