posted by Jiri Wagner
The C-17 is the most flexible airlift aircraft to enter the Air Force's inventory. The ultimate measure of airlift effectiveness is the ability to rapidly project and sustain an effective combat force close to a potential battle area.
Threats to U. S. interests have changed in recent years, and the size and weight of U.S. mechanized firepower and equipment have grown in response to improved capabilities of potential adversaries. This trend has significantly increased air mobility requirements, particularly in the area of heavy outsized cargo. As a result, additional airlift is needed to meet possible contingencies worldwide. The C-17 helps address these shortfalls in the current airlift force. The C-17 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. The aircraft is also able to perform theater airlift missions when required.
The inherent flexibility and performance characteristics of the C-17 force improves the ability of the total airlift system to fulfill the worldwide air mobility requirements of the United States. Reliability and maintainability are two outstanding benefits the C-17 system brings with it. The C-17's system specifications impose a demanding set of reliability and maintainability requirements. These requirements include an aircraft mission completion success probability of 93 percent, only 18.6 aircraft maintenance manhours per flying hour, and full and partial mission capable rates of 74.7 and 82.5 percent respectively for a mature fleet with 100,000 flying hours. The McDonnell Douglas Aerospace warranty assures these figures will be met. The C-17 measures approximately 174 feet long with a 170-foot wingspan. The aircraft is powered by four fully reversible Pratt & Whitney F117-PW-100 engines (the commercial version is currently used on the Boeing 757). Each engine is rated at 40,900 pounds of thrust. The thrust reversers direct the flow of air upward and forward to avoid ingestion of dust and debris. The aircraft is operated by a crew of three (pilot, copilot and loadmaster).
Cargo is loaded onto the C-17 through a large aft door that accommodates military vehicles and palletized cargo. The C-17 can carry virtually all of the Army's air-transportable, outsized combat equipment. The C-17 is also able to airdrop paratroopers and cargo. Maximum payload capacity of the C-17 is 170,900 pounds, and its maximum gross takeoff weight is 585,000 pounds. With a payload of 130,000 pounds and an initial cruise altitude of 28,000 feet, the C-17 has an unrefueled range of approximately 5,200 nautical miles. Its cruise speed is approximately 450 knots (.77 Mach).
The design of this aircraft lets it operate on small, austere airfields. The C-17 can take off and land on runways as short as 3,000 feet and as narrow as 90 feet wide. Even on such narrow runways, the C-17 can turn around by using its backing capability while performing a three-point star turn. Maximum use has been made of off-the-shelf and commercial equipment, including Air Force standardized avionics. The C-17 made its maiden flight on Sept. 15, 1991. The aircraft is operated by the Air Mobility Command with initial operations at Charleston AFB, S.C., with the 437th Airlift Wing and the 315th Airlift Wing (Air Force Reserve). The C-17 program is managed by the Aeronautical Systems Center, Wright-Patterson AFB, Ohio.
|Cargo and troop transport
|McDonnell Douglas Corp.
|Four Pratt & Whitney F117-PW- 100 turbofan engines
|4x 41,725 lb
|4x 185.6 kN
|173 ft 11 in
|55 ft 1 in
|3,800 sq ft
|353.02 sq m
|85 ft 2 in
|height forward of the wing
|12 ft 4 in
|height aft of the wing
|13 ft 6 in
|three (two pilots and loadmaster)
|144 combat troops or 102 fully equipped paratroops or 48 litter and 54 sets or 172,200 lb (78,108 kg) load (18 paletts)
The four builders are shown in the lower left image above. Colin Straus, the owner, is at the nose of the aircraft.
This 1/9th scale radio-controlled C-17 model was built in the United Kingdom. To date it has about 20 flights. It was built as the centerpiece of a 15 program television series produced in the U.K. for the Home and Leisure satellite TV channel. Built with the aid of three friends, it took one year to build and is powered with 4 Jetcat P-120 turbines with a total thrust of 108 lbs. The model weighs over 250 lbs fuelled, and carries 12.5 liters (3.3 US gallons) of 95% kerosene and 5% turbine oil fuel. Other details include 5 Futaba PCM receivers, 16 battery packs (93 cells), 20 Futaba servos, on board air compressor, electro/pneumatic retracts, etc. Wingspan is 20 feet 8 inches, and the top of the fin is 74 inches (6 feet 2 inches) above the ground. Takeoff weight is 264 lbs. Complete with retractable landing gear and pneumatically operated flaps, the rear cargo doors open and they drop an r/c jeep on a pallet, as well as 2 free-fall r/c parachutists. The model also has smoke systems on both of the inboard turbines, and uses 2.4 GHz data link to provide real-time data to a laptop computer on the ground while in flight, this data includes airspeed, turbine RPM, EGT, fuel consumption, etc. It is covered in fiberglass and epoxy resin. It's built mainly from balsa and ply, with many glass and carbon fiber moldings to reduce weight. This C-17 Globemaster III is one of the largest jet models in the world today!
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