C-17 Globemaster III

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The C-17 Globemaster III is a strategic airlifter manufactured by Boeing Integrated Defense Systems, used by the United States Air Force and the Royal Air Force.

Contents

Mission

The C-17 Globemaster III is the newest purpose-built cargo aircraft to enter the U.S and western airforces. It is capable of rapid strategic delivery of troops and all types of cargo to main operating bases or directly to forward bases in the deployment area. This aircraft is also capable of performing tactical airlift and airdrop missions when required. The inherent flexibility and performance of the C-17 force improves the ability of the total airlift system to fulfill the worldwide air mobility requirements of the United States.

The ultimate measure of airlift effectiveness is the ability to rapidly project and sustain an effective combat force close to a potential battle area. In recent years the size and weight of U.S. mechanized firepower and equipment have grown, which has significantly increased air mobility requirements, particularly in the area of large or heavy outsize cargo. As a result, newer and more flexible airlift aircraft such as the C-17 are needed to meet potential armed contingencies, peacekeeping or humanitarian missions worldwide.

Features

The C-17 is powered by four, fully reversible, Pratt & Whitney PW2000 turbofan engines (the Department of Defense designation for the commercial Pratt and Whitney PW2040, currently used on the Boeing 757.) Each engine is rated at 40,440 lbf (180 kN) of thrust. The thrust reversers direct the flow of air upward and forward. This facilitates a decreased rate of ingestion of foreign object debris (FOD) as well as reverse thrust capable of backing the aircraft. Additionally, the C-17's thrust reversers can be used at idle-reverse in flight for added drag in maximum-rate descents.

The aircraft is operated by a minimum crew of three (pilot, copilot, and loadmaster). Cargo is loaded onto the C-17 through a large aft door that accommodates both rolling stock (vehicles, trailers, etc.) and palletized cargo. The cargo floor has rollers (used for palletized cargo) that can be flipped to provide a flat floor suitable for rolling stock. One of the larger pieces of rolling stock that this aircraft can carry is the 70-ton M1 main battle tank.

Maximum payload capacity of the C-17 is 170,900 lb (77,500 kg), and its maximum gross takeoff weight is 585,000 lb (265,350 kg). With a payload of 160,000 lb (72,600 kg) and an initial cruise altitude of 28,000 ft (8,500 m), the C-17 has an unrefueled range of approximately 2,400 nautical miles (4,400 km) on the first 71 units, and 2,800 nautical miles (5,200 km) on all subsequent units, which are extended-range models with an additional fuel tank in the center wing box. Its cruise speed is approximately 450 knots (833 km/h) (.74 Mach). The C-17 is designed to airdrop 102 paratroopers and equipment.

The C-17 is designed to operate from runways as short as 3,000 ft (900 m) and as narrow as 90 ft (27 m). In addition, the C-17 can operate out of unpaved, unimproved runways (although this is rarely done due to the increased possibility of damage to the aircraft). The thrust reversers can be used to back the aircraft and reverse direction on narrow taxiways using a three-point (or in some cases, multi-point) turn maneuver.

Background

In the 1970s, USAF began looking for a replacement for the C-130 Hercules tactical airlifter. The Advanced Medium STOL Transport, (AMST) competition was held, with Boeing proposing the YC-14, and McDonnell Douglas proposing the YC-15. The AMST competition was cancelled before a winner had been selected.

By the early-1980s, the USAF found itself with a very large, but aging fleet of C-141 Starlifters. Some of the C-141s had major structural problems as a result of heavy use. Compounding matters, USAF historically never possessed sufficient strategic airlift capabilities to fulfill its airlift requirements. In response, McDonnell Douglas elected to develop the YC-15 as the basis for a new aircraft. This aircraft, by then designated the C-17A Globemaster III, was ordered in August 1981. The new aircraft differed in having swept wings, increased size, and more powerful engines. This would allow it to perform all work performed by the C-141, but to also fulfill some of the duties of the C-5 Galaxy, so that the C-5 fleet would be freed up for larger, more outsize cargo.

Development continued until December, 1985 when a full-scale production contract was signed. Its maiden flight was on September 15, 1991 from the McDonnell-Douglas west coast plant in Long Beach, California. This aircraft (T-1) and five more production models (P1-P5) participated in extensive flight testing and evaluation at Edwards AFB. Soon after the C-17 reached production, McDonnell Douglas was acquired by its former competitor, Boeing.

USAF background

The first production model was delivered to Charleston Air Force Base, S.C., on July 14, <a href="/wi