The Lockheed C-141 Starlifter is a retired military strategic airlifter that served with the Military Air Transport Service (MATS), its successor organization the Military Airlift Command (MAC), and finally the Air Mobility Command (AMC) of the United States Air Force (USAF).
The aircraft also served with airlift and air mobility wings of the Air Force Reserve (AFRES), later renamed Air Force Reserve Command (AFRC), the Air National Guard (ANG) and, later, one air mobility wing of the Air Education and Training Command (AETC) dedicated to C-141, C-5, C-17 and KC-135 training.
Introduced to replace slower propeller driven cargo planes such as the Douglas C-124 Globemaster II and Douglas C-133 Cargomaster, the C-141 was designed to requirements set in 1960 and first flew in 1963.
Production deliveries of an eventual 285 planes began in 1965: 284 for the USAF, and a company demonstrator later delivered to National Aeronautics and Space Administration (NASA) for use as an airborne observatory.
The aircraft remained in service for over 40 years until the USAF withdrew the last C-141s from service in 2006, after replacing the airlifter with the C-17 Globemaster III.
The Lockheed C-141 Starlifter is a long-range strategic airlifter, designed for transporting large quantities of either cargo or passengers.
It is powered by an arrangement of four TF33 turbofan engines, each capable of generating up to 21,000 pounds-force (93 kN) of thrust; these were installed in pods beneath the high-mounted swept wing.
The underside accommodates the retractable tricycle landing gear, consisting of a twin-wheel nose unit and four-wheel main units, the latter of which retract forward into fairings set onto each side of fuselage.
The flight deck is typically operated by a crew of four.
The use of a high-mounted wing enabled internal clearance in the cargo compartment of 10 feet (3.0 m) wide, 9 ft (2.7 m) high and 70 ft (21 m) long.
Accordingly, the C-141 was capable of carrying, for example, a complete LGM-30 Minuteman intercontinental ballistic missile (ICBM) in its container; it was capable of carrying a maximum of 70,847 pounds (32,136 kg) over short distances and carry up to 92,000 pounds (42,000 kg) when appropriately configured to carry the Minuteman, which lacked other equipment.
In terms of personnel, the aircraft could carry a maximum of 154 fully equipped troops, 123 paratroopers or 80 litter patients at a time.
In practice, it was discovered that under typical conditions, the cargo deck of the C-141A would run out of volume before the maximum weight value could be reached.
In terms of ground logistics, an important aspect of the C-141 was the floor height of the cabin being only 50 inches (130 cm) above the ground, enabling easy access to the cabin via the large rear doors incorporated into the upwards-sweeping rear fuselage.
This section is furnished with a large single-piece hydraulically actuated loading ramp for simplified loading/unloading of both vehicles and general cargo.
The two side-facing rear doors were designed to allow the type to be used for dropping paratroopers (in August 1965, the C-141 performed the first such drop from a jet-powered aircraft).
The rear cargo doors could be also opened in flight to perform airborne cargo drops.
The original Starlifter model, designated C-141A, could carry 154 passengers, 123 paratroopers or 80 litters for wounded with seating for 16.
A total of 284 A-models were built.
The C-141A entered service in April 1965.
It was soon discovered that the aircraft’s volume capacity was relatively low in comparison to its lifting capacity; it generally ran out of physical space before it hit its weight limit.
The C-141A could carry ten standard 463L master pallets and had a total cargo capacity of 62,700 pounds (28,400 kg).
It could also carry specialized cargoes, such as the Minuteman missile.
NASA obtained Lockheed’s C-141 demonstrator, designated L-300.
The airplane was modified to house the Kuiper Airborne Observatory (KAO) telescope for use at very high altitudes.
This aircraft, NC-141A is in storage at NASA Ames Research Center, Moffett Federal Airfield, California.
The KAO was retired in 1995 and was replaced by the 747SP-based Stratospheric Observatory for Infrared Astronomy (SOFIA).
In service, the C-141 proved to “bulk out” before it “grossed out”, meaning that it often had additional lift capacity that went wasted because the cargo hold was full before the plane’s weight capacity had been reached.
To correct the perceived deficiencies of the original model and utilize the C-141 to the fullest of its capabilities, 270 in-service C-141As (vast majority of the fleet) were stretched, adding needed payload volume.
The conversion program took place between 1977 and 1982, with first delivery taking place in December 1979.
These modified aircraft were designated C-141B.
It was estimated that this stretching program was equivalent to buying 90 new aircraft, in terms of increased capacity. Also added was a boom receptacle for inflight refuelling.
The fuselage was stretched by adding “plug” sections forward and aft of the wings, lengthening the fuselage a total of 23 feet 4 inches (7.11 m) and allowing the carriage of 103 stretchers for wounded, 13 standard pallets, 205 troops, 168 paratroopers, or an equivalent increase in other loads.
In 1994, a total of 13 C-141Bs were given SOLL II (Special Operations Low-Level II) modifications, which gave the aircraft a low-level night flying capability, enhanced navigation equipment, and improved defensive countermeasures.
These aircraft were operated by AMC in conjunction with Air Force Special Operations Command (AFSOC).
A total of 63 C-141s were upgraded throughout the 1990s to C-141C configuration, with improved avionics and navigation systems, to keep them up to date.
New capabilities, including traffic collision avoidance system (TCAS) and Global Positioning System (GPS), were added to aircraft that received this upgrade package.
This variant introduced some of the first glass cockpit technology to the aircraft, as well as improving reliability by replacing some mechanical and electromechanical components with more modern electronic equivalents.