Lockheed C-5 Galaxy

Summary

Description

In 1961, studies commenced for a heavy jet transport intended to replace the Douglas C-133 Cargomaster and supplement the Lockheed C-141 Starlifter. This effort was driven by the US Army's requirement for a cargo bay larger than that of the C-141. This initial need evolved into the CX-4 specification, which was subsequently superseded by the CX-HLC requirement in late 1963. The CX-HLC specified a four-engine airlifter with defined parameters for weight, payload capacity, speed, and cargo compartment dimensions. An official request for proposal for the "Heavy Logistics System" (CX-HLS) was released in April 1964. Proposals were received from Boeing, Douglas, General Dynamics, Lockheed, and Martin Marietta for the airframe, and from General Electric, Curtiss-Wright, and Pratt & Whitney for the engines. Boeing, Douglas, and Lockheed were awarded one-year study contracts for the airframe designs, while General Electric and Pratt & Whitney received contracts for engine development. Lockheed's airframe design was selected in September 1965, and GE's TF39 engine was chosen in August 1965. The first C-5A Galaxy, serial number 66-8303, was rolled out on 2 March 1968, and flight testing commenced on 30 June 1968. Initial testing revealed discrepancies in drag and lift coefficients compared to wind tunnel predictions. Aircraft weight became a critical issue during development, exceeding guaranteed limits by the time the ninth aircraft was delivered, and wing strength was found to be below requirements. These issues, along with cost overruns, resulted in a congressional investigation in 1968 and 1969, and the program became the first to exceed a $1 billion cost overrun. Testing was completed in December 1969, and the first C-5A was transferred to Altus Air Force Base, Oklahoma. Lockheed delivered the first operational Galaxy in June 1970. Lockheed faced financial challenges, partly attributable to the C-5's development, necessitating government loans to maintain operations.

The C-5 is characterized as a large, high-wing cargo aircraft featuring a high T-tail fin stabilizer and powered by four turbofan engines mounted on pylons beneath wings swept at 25°. The original C-5A was powered by TF39 engines; later variants utilized GE CF6 engines. The aircraft incorporates a two-deck configuration, with a flight operations and passenger deck situated above the main cargo deck. The upper deck provides seating for up to 80 passengers in rear-facing seats and loadmaster crew in forward-facing seats. Both the nose and tail sections feature bay doors that open to facilitate "drive-through" loading and unloading operations. The landing gear includes high-flotation main gear with 28 wheels designed to distribute the aircraft's gross weight on varying surfaces. The rear main landing gear is capable of being made to caster, rotating 90° post-takeoff before retraction to reduce the turning radius. The "kneeling" feature of the landing gear lowers the aircraft when parked, aligning the cargo deck with truck-bed height for loading efficiency. The aircraft incorporates a malfunction detection analysis and recording system.

The C-5 Galaxy is primarily designed for transport and lacks integral offensive or defensive weapon systems. Its function is the carriage of diverse cargo, including vehicles, equipment, and supplies. The internal cargo compartment dimensions are 121 ft (37 m) in length, 13.5 ft (4.1 m) in height, and 19 ft (5.8 m) in width, resulting in a volume exceeding 31,000 cu ft (880 m3). This capacity allows for the transport of up to 36 463L master pallets or a combination of palletized goods and vehicles. The full-width and height opening of the nose and aft cargo doors facilitates loading of oversized equipment, with full-width ramps enabling loading of double rows of vehicles from either end. The C-5 can transport nearly all types of military combat equipment, including an Army armored vehicle-launched bridge weighing 74 short tons (67 t), and can accommodate up to six Boeing AH-64 Apache helicopters or five Bradley Fighting Vehicles in a single load. The maximum payload capacity is 281,000 lb (127,459 kg).

The USAF has operated the C-5 since 1969, providing support for US military operations in conflicts such as Vietnam, Iraq, Yugoslavia, and Afghanistan. The aircraft also provided support during conflicts including aid to Israel during the Yom Kippur War and support for coalition operations during the Gulf War. The Galaxy has also been utilized for humanitarian missions, delivering aid and providing disaster relief, and has supported the US space program. Early in its operational history, during the Vietnam War, C-5s transported equipment, troops, and small aircraft. During the concluding phase of the conflict, C-5s were involved in evacuation flights. An incident during Operation Iraqi Freedom resulted in damage to a C-5 by a projectile. Early operational issues included the discovery of cracks in the wings of several aircraft, limiting the C-5A fleet to 80% of maximum design loads. By 1980, peacetime general cargo payloads were restricted to 50,000 lb (23,000 kg) on C-5As. As of August 2018, 52 C-5Ms were in service.

Main Variants:

• C-5A: The initial production version delivered to the U.S. Air Force, later undergoing a program to install new strengthened wings.

• C-5B: An improved version of the C-5A incorporating modified wings, simplified landing gear, upgraded engines, and updated avionics.

• C-5C: Two modified C-5As featuring enlarged internal cargo capacity for oversized payloads by removing the rear passenger compartment, splitting the rear cargo door, and adding a movable aft bulkhead.

• C-5D: A proposed upgrade variant that was not produced.

• C-5M Super Galaxy: A modernized variant incorporating upgraded avionics, more powerful engines, and other enhancements.

Technical specifications

Current operating countries

Country		Units
	United States	52

Numbers in parentheses, e.g. '(+5)', indicate units ordered but not yet delivered.

All operators

United States

Photo of C-5 Galaxy