Lockheed C-141 Starlifter - Design and Development

Design and Development

In the early 1960s, the United States Air Force Military Air Transport Service (MATS) relied on a substantial number of propeller-driven aircraft for strategic airlift. As these aircraft were mostly obsolescent designs and the Air Force needed the benefits of jet power, the USAF ordered 48 Boeing C-135 Stratolifters as an interim step. The C-135 was a useful stop-gap, but only had side-loading doors and most bulky and oversize equipment would not fit, especially that employed by the U.S. Army.

In the spring of 1960 the Air Force released Specific Operational Requirement 182, calling for a new aircraft that would be capable of performing both strategic and tactical airlift missions. The strategic role demanded that the aircraft be capable of missions with a radius of at least 3,500 nmi (4,000 mi, 6,500 km) with a 60,000 lb (27,000 kg) load. The tactical role required it to be able to perform low-altitude air drops of supplies, and carry and drop paratroops in combat. Several companies responded to SOR 182, including Boeing, Lockheed and General Dynamics.

Lockheed responded to the requirement with a unique design: the Lockheed Model 300, the first large jet designed from the start to carry freight. The Model 300 had a swept high-mounted wing with four 21,000 lbf (93.4 kN) thrust TF33 turbofan engines pod-mounted below the wings. An important aspect was the cabin floor's height of only 50 in (1.27 m) above the ground, allowing easy access to the cabin through the rear doors. The two rear side doors were designed to allow the aircraft to drop paratroopers (in August 1965 the type performed the first paratroop drop from a jet-powered aircraft). The rear cargo doors could be opened in flight to allow airborne freight drops. The shoulder-mounted wings gave internal clearance in the cargo hold of 10 ft (3.05 m) wide, 9 ft (2.74 m) high and 70 ft (21.34 m) long. The size enabled the Starlifter to carry, for example, a complete LGM-30 Minuteman intercontinental ballistic missile in its container. The aircraft was capable of carrying a maximum of 70,847 lb (32,136 kg) over short distances, and up to 92,000 lb (41,730 kg) in the version configured to carry the Minuteman, which stripped other equipment. The aircraft could also carry up to 154 troops, 123 paratroopers or 80 litter patients.

President John F. Kennedy's first official act after his inauguration was to order the development of the Lockheed 300 on 13 March 1961, with a contract for five aircraft for test and evaluation to be designated the C-141. One unusual aspect of the aircraft was that it was designed to meet both military and civil airworthiness standards. The prototype C-141A serial number 61-2775 was manufactured and assembled in record time, being rolled out of the Lockheed factory at Marietta, Georgia on 22 August 1963 and first flying on 17 December, the 60th anniversary of the Wright brothers' first flight. The company and the Air Force then started an operational testing program and the delivery of 284 aircraft, initially to units of the MATS, later renamed the Military Airlift Command (MAC) in 1966.

An effort to sell the aircraft on the civilian market resulted in provisional orders from Flying Tiger Line and Slick Airways for four aircraft each. These were to be a stretched version, 37 ft (11.28 m) longer than the C-141A, and marketed as the L-300 SuperstarLifter. Other changes were also incorporated to make more commercial including a different yoke. The development was not sustained and only one civilian demonstration aircraft was built. When no commercial sales were made Lockheed donated the aircraft to NASA.