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Comparison highlights size and role differences between Lockheed C-5M Super Galaxy and Boeing 747

Comparison highlights size and role differences between Lockheed C-5M Super Galaxy and Boeing 747
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Jim Taiclet, Chairman, President and Chief Executive Officer | Lockheed Martin Corporation

The Lockheed C-5 Galaxy and the Boeing 747 were both pioneers in the widebody aircraft category, with the C-5 making its first flight in June 1968 and the 747 entering service in January 1970. While their primary roles differ—the C-5 as a military cargo transporter and the 747 as a commercial airliner—both share several design similarities, including a second deck for the cockpit and use of high-bypass turbofan engines.

The United States Air Force (USAF) initiated development of the C-5 Galaxy through a Request for Proposal in 1964 for an aircraft much larger than its predecessor, the Lockheed C-141 Starlifter. Lockheed's design was chosen, and General Electric developed the TF39 engine specifically for this aircraft. Boeing, having lost that competition, incorporated elements from its submission into what would become the 747, following a request from Pan American World Airways President Juan Trippe for a large-capacity passenger jet.

The Boeing 747 was produced in multiple variants over more than five decades. Most models retained similar dimensions until the introduction of the 747SP, which was shorter to improve range. The most significant changes came with the final variant, the 747-8, which featured an extended fuselage, enlarged wingspan, new engines, and increased maximum takeoff weight (MTOW).

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For comparison:

- The Boeing 747-8 measures 250 feet, two inches (76.25 meters) in length with a wingspan of 224 feet, seven inches (68.5 meters), and an MTOW of 447.7 metric tons.

- The Lockheed C-5 Galaxy is slightly shorter at 247 feet, one inch (75.31 meters) long with a wingspan of 222 feet, nine inches (67.89 meters), and an MTOW of 381 metric tons.

Despite these differences, both aircraft are among the largest ever built. The C-5M Super Galaxy is currently the most advanced version of the C-5 series, featuring upgraded avionics and new General Electric F138 engines.

In terms of operational roles, size is crucial for the C-5 Galaxy’s effectiveness within USAF operations. Its vast cargo hold allows it to transport heavy equipment such as multiple Chinook helicopters or M1 Abrams tanks simultaneously. It also supports presidential travel by carrying vehicles for motorcades.

While size initially contributed to the commercial success of the Boeing 747—with over 1,573 units sold—it eventually became less advantageous as airlines favored smaller twin-engine jets like the Boeing 777-300ER due to greater efficiency and lower risk.

According to current plans, upgrades to keep the C-5M fleet operational will extend its service life into at least the 2040s—about seventy years after its introduction—until it is replaced by a future airlifter that may be smaller if designed to also replace other types like the C-17 Globemaster III.

"Size was the point of the C-5 Galaxy, and the United States Air Force uses the C-5 to do what no other aircraft can do," states one section on its unique capabilities.

With few comparable aircraft in operation today besides models like Airbus’s A380—which remains longer—the Lockheed C-5M Super Galaxy continues to serve as one of history’s largest production airplanes.

Organizations Included in this History
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