McDonnell Douglas C-17 "Globemaster III"
Aircraft
MD C-17 Globemaster III
Type
Heavy Transport Aircraft
Crew
3
Unit Cost
US $258 million
Main Operator
United States Air Force
Number Built
158 (2006)
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McDonnell Douglas C-17 Program Milestones
Maiden Flight
September 15, 1991
Production Start
Early 1990s
Introduction
July 14, 1993
First User
United States Air Force


McDonnell Douglas C-17 Aircraft Dimensions
Wing Span
165 feet 0 inch (50.29 m)
Length
170 feet 8 inch (52.02 m)
Height
53 feet 6 inch (16.31 m)
Wing Area
3.800 sq ft

McDonnell Douglas C-17 Weights
Empty Weight
259,000 lb (117,480 kg)
Max Take-Off Weight
572,000 lb (259,455 kg)
Max Payload
172,200 lb (78,110 kg)

McDonnell Douglas C-17 Globemaster III
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McDonnell Douglas C-17 Globemaster III

McDonnell Douglas C-17 Powerplants
4 x PW2037 turbofans
37,600 lbf


McDonnell Douglas C-17 Radius & Performance
Range
2,240 nm (4,482 km)
Service Ceiling
45,000 feet (13,716 m)
Max Cruising Speed (Alt)
Mach 0.775
Max Cruising Speed (Low)
350 kts (648 km/h)
Wing Loading
150 lb/sq ft
Take-off Roll
7,600 feet (2,320 m)
Landing Roll
3,000 feet (915 m)
Thrust/Weight Ratio
0.277

McDonnell Douglas C-17 Globemaster III Typical Take-off

McDonnell Douglas C-17
On 29 August 1981 the US Air Force announced that McDonnell Douglas had been selected as prime contractor to develop a new C-17 long-range cargo aircraft, following the evaluation of three designs entered for its C-X competition. The C-X programme is for a long-range, heavy-lift air-refuellable cargo transport, intended primarily to provide inter-theatre airlift of outsize loads, including tanks and infantry fighting vehicles, directly into airfields in potential conflict areas. One of the design requirements was therefore outstanding STOL (Short Take-Off and Landing) performance.

The C-X is, however, only one gradient of an Air Force airlift improvement plan that also includes enhancement of current aircraft capabilities, and expanded cargo-carrying capability for the Civil Reserve Air Fleet. Therefore, selection of the McDonnell Douglas C-17 did not represent an Air Force commitment to build at that stage, since the USAF was still evaluating alternative ways of overcoming the present shortfall in airlift capability. One of these alternatives included the purchase of an additional batch of Lockheed C-5 Galaxies and/or off-the-shelf commercial transport aircraft. Award of a C-17 contract was therefore dependant upon Defense Department approval of the Air Force's overall plan for satisfying its airlift requirements.

In January 1982 the Air Force stated that it did not plan full-scale developement and production of the C-17 at that time. However, nearly half a year later, on 26 July 1982 McDonnell Douglas announced an award worth $31.6 million for a modestly paced research and development programme, to include those C-17 technologies that would also benefit other airlift programmes, and preserving the option to proceed to full-scale engineering development of the C-17 if eventually deemed appropriate. The technologies to be investigated include flaps on a swept supercritical wing, winglets tailored to the supercritical wing design, and an engine core thrust reverser.

The McDonnell Douglas C-17 makes use of technology developed for its earlier YC-15 advanced medium STOL transport prototypes that would be able to airlift outsize combat equipment which at that time could only be carried by the Lockheed C-5 Galaxy, and offer a short field performance only offered by the C-130 Hercules.

 

McDonnell Douglas C-17 Design
The McDonnell Douglas C-17 Globemaster is a long-range heavy-lift cargo transport aircraft. Its airframe includes some general survivability features which include ample provisions for crew and troop shielding; redundant load paths in order to minimize the effects of battle damage, and a facility for critical line-replaceable units (LRU) to be replaced in flight without removing other equipment.

The aircraft is fitted with a supercritical cantilever high-wing construction with 25 degrees sweepback, and NASA-type winglets at each tip. It has full-span leading edge slats and an externally-blown flap system, developed from that used on the McDonnell Douglas YC-15 in order to reduce final approach and landing speeds by directing engine efflux over single-hinged, double-slotted Fowler-type trailing edge flaps. These flaps are constructed of titanium and use superplastic-forming/diffusion-bonding techniques along approximately two-thirds of each trailing edge.

The fuselage is of the conventional semi-monocoque structure and unswept at the rear. In order to ease loading and unloading of cargo or troops, the C-17 has a rear-loading ramp/door in the underside of the rear fuselage.

The McDonnell Douglas C-17 has a hydraulically retractable tricycle landing gear, with free-fall emergency extension capability. It has a twin-wheel nose unit and two six-wheel main units, all designed for a maximum sink rate of 5.03 m/s (16.5 ft/s) and operation from paved or unpaved runway strips. The main-wheel units consist of two legs in tandem with three wheels on each leg. They retract into the bottom of the large fairings on the lower fuselage sides while the nose unit retracts in a forward position.

The C-17 is operated by a crew of two; consisting of a pilot and co-pilot, side by side on the flight deck, plus a loadmaster. Provision for additional crew members is available in case specific a mission require this. Furthermore, the aircraft is capable of accomodating 102 paratroops or 55,000 lb of airdrop loads. In fact, the C-17 would be the only aircraft able to airdrop ousize firepower such as the US Army's infantry vehicles.

Systems onboard the aircraft include fully-redundant flight control and hydraulic systems; an independant fuel feed system; electrical system; Auxiliary Power Unit (APU) operable in flight; explosion-protection system; and a fire suppression system.

The MD C-17 has an automatic flight control system, with advanced digital avionics and six CRT displays; dual vertical situation displays (VSD) and duel horizontal situation displays (HSD), plus com and nav mission cockpit displays (CDU). A Head-Up-Display is installed on the left-hand side of the flight deck which gives the pilot important aircraft information and can be obtained without having to swith views.