C17 Globemaster

The Boeing (formerly McDonnell Douglas) C17 Globemaster III is an American strategic airlifter manufactured by Boeing Integrated Defense Systems, and operated by the United States Air Force, British Royal Air Force, the Royal Australian Air Force, and the Canadian Forces Air Command. NATO also has plans to acquire the airlifter.

The C17 Globemaster III 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. It is also capable of performing tactical airlift, medical evacuation and airdrop missions. The C17 takes its name from two previous heavy lifter aircraft, the C74 Globemaster and the C124 Globemaster II.

The 1970's, USAF began looking for a replacement for the C130 Hercules tactical airlifter. The Advanced Medium STOL Transport (AMST) competition was held, with Boeing proposing the YC14, and McDonnell Douglas proposing the YC15. Despite both entrants exceeding specified requirements, the AMST competition was canceled before a winner had been selected.

 

By the early 1980's, the USAF found itself with a large aging fleet of C141 Starlifters. Some of the C141s had major structural problems due to heavy use. Compounding matters, USAF historically never possessed sufficient strategic airlift capabilities to fulfill its airlift requirements. In response, McDonnell Douglas elected to develop a new aircraft using the YC15 as the basis. McDonnell Douglas won the contract to build its proposed aircraft, by then designated the C17A Globemaster III, on August 28th, 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 C141, but to also fulfill some of the duties of the C5 Galaxy, freeing the C5 fleet for larger outsize cargo.

Development continued until December 1985 when a full scale production contract was signed for 210 aircraft. Development problems and limited funding caused delays in the late 1980's. Questions were also raised about more cost effective alternatives during this time. In April 1990, Defense Secretary Cheney reduced the order from 210 to 120 aircraft. The C17's maiden flight was on September 15th, 1991 from the McDonnell Douglas west coast plant in Long Beach, California, about a year behind schedule. This aircraft (T1) and five more production models (P1-P5) participated in extensive flight testing and evaluation at Edwards AFB. In late 1993, the DoD gave the contractor two years to solve production and cost overrun problems or face termination of the contract after the delivery of the fortieth aircraft. By accepting the 1993 terms, McDonnell Douglas incurred a loss of nearly US$1.5 billion on the development phase of the program.

In April 1994, the C17 program was still experiencing cost overruns, and did not meet weight, fuel burn, payload and range specifications. Airflow issues caused problems with parachutes and there were various other technical problems with mission software, landing gear, etc. A July 1994 GAO document revealed that to justify investing in the C17 rather than in the C5, Air Force and DoD studies from 1986 and 1991 had claimed that the C17 could use 6,400 more runways (outside the US) than the C5. It was later discovered that this study had only considered the runway dimensions, but not their strength or Load Classification Numbers (LCN). The C5 has a lower LCN than the C17, although the US Air Force places both in the same broad Load Classification Group (LCG). When considering runway dimensions and their load ratings, the C17's worldwide runway advantage over the C5 shrank from 6,400 to 911 airfields. However, the C17's ability to use lower quality, austere airfields was not considered.

A January 1995 GAO report revealed that while the original C17 budget was US$41.8 billion for 210 aircraft, the 120 aircraft already ordered at that point had already cost US$39.5 billion. In March 1994, the U.S. Army had decided it no longer needed the 60,000 lb (27,000 kg) Low Altitude Parachute Extraction System (LAPES) delivery that the C17 was supposed to provide, feeling that the 42,000 lb (19,000 kg) capability of the C130 Hercules was sufficient. It was decided not to conduct C17 LAPES training beyond the testing of a 42,000 lb (19,000 kg) LAPES delivery. There were still airflow problems making it impossible for the C17 to meet its original airdrop requirements. A February 1997 GAO Report revealed that a C17 with a full payload could not land on 3,000 feet (900 m) wet runways, for simulations suggested 5,000 ft (1,500 m) was required.

By the mid 1990's, most of the problems had been resolved. The first C17 squadron was declared operational by the U.S. Air Force in January 1995. In 1996, DoD ordered another 80 aircraft for a total of 120. In 1997 McDonnell Douglas merged with its former competitor, Boeing. In 1998, the order was increased to 134 units and in August 2002 to 180.

In July 2006, C17A production was planned to end in 2009 unless Boeing received a follow-on order in sufficient time to allow the production pipeline to remain in operation. If such an order is placed, Boeing would begin C17B production in 2010. The proposed C17B would be capable of landing on sandy beaches and other areas off-limits to the C17A.

On August 18th, 2006 Boeing announced it was telling suppliers to stop work on parts for uncommitted C17's. This move is the first step in shutting down production if no new plane orders were received from the US Government. However, just one month later on September 21st, a House and Senate conference committee approved a US$447 billion defense bill for 2007, that includes US$2.1 billion for 10 additional C17's which is seven more planes than either chamber originally approved in separate versions of their funding language. The additional purchase follows intense lobbying by the Boeing, as well as politicians from California, where the plane is made, and Missouri, where Boeing's defense business is based. However, this extends the life of the program for only one additional year, to 2010.

On March 2nd, 2007, Boeing announced the C17 production line may end in mid 2009 due to the lack of additional U.S. government and international orders.

A total of 190 C17's are contracted for delivery to the USAF as of October 24th, 2007. Efforts are underway to add a further 10 C17's to a funding/supplemental bill so that production may be extended to 2010 and to allow for further potential FMS purchases to take effect.

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. The C17 can airlift such cargo close to a potential battle area.

The C17 is powered by four fully reversible, F117 PW 100 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 40,400 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 C17's thrust reversers can be used in flight at idle reverse 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 C17 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 Abrams tank.

Maximum payload capacity of the C17 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 C17 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 using the sealed center wing bay as a fuel tank. These units are informally referred to by Boeing as the C17 ER. Its cruise speed is approximately 450 knots (833 km/h) (0.76 Mach). The C17 is designed to airdrop 102 paratroopers and equipment.

The C17 is designed to operate from runways as short as 3,500 ft (1,064 m) and as narrow as 90 ft (27 m). In addition, the C17 can operate out of unpaved, unimproved runways (although there is 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.

The first production model was delivered to Charleston Air Force Base, SC, on July 14th, 1993. The first squadron of C17's, the 17th Airlift Squadron, was declared operationally ready on January 17, 1995. The C17 has broken 22 records for oversized payloads. The C17 was awarded aviation's most prestigious award, the Collier Trophy in 1994.

The Air Force originally programmed to buy a total of 120 C17's, with the last one being scheduled for delivery in November 2004. The fiscal 2000 budget funded another 14 aircraft for Special Operations Command. Basing of the original 120 C17's was at Charleston AFB, South Carolina, McChord Air Force Base, Washington (first aircraft arrived in July 1999), Altus AFB, Oklahoma, and the 172d Airlift Wing at Jackson, Mississippi. Basing of the additional 13 aircraft went to McGuire Air Force Base, New Jersey, Elmendorf Air Force Base, Alaska, Hickam Air Force Base, Hawaii, Dover Air Force Base, Delaware and Travis Air Force Base, California. An additional 60 units were ordered in May of 2002. In FY 2006, Eight C17s were delivered to the 452d Air Mobility Wing at March ARB, California. These C17's are the only ones strictly under direct command of the Air Force Reserve Command. In 2007, Congress appropriated funds for 10 additional USAF C17's, bringing the total planned fleet size (on order + delivered) to 190.

The C17 was used to deliver military goods and humanitarian aid during Operation Enduring Freedom in Afghanistan as well as Operation Iraqi Freedom in Iraq. On March 26th, 2003, fifteen USAF C17's participated in the biggest combat airdrop since the United States invasion of Panama in December, 1989: the night-time airdrop of 1,000 paratroopers from the 173rd Airborne Brigade occurred over Bashur, Iraq. It opened the northern front to combat operations and constituted the largest formation airdrop carried out by the United States since World War II.

USAF C17s have also been used to assist US Allies transport military equipment. This has included the transportation of Canadian armored vehicles to Afghanistan in 2003 and the redeployment of Australian forces in Australia and the Solomon Islands during the Australian led military deployment to East Timor in 2006. In late September and early November 2006, USAF C17's flew 15 Canadian Forces Leopard C2 tanks from Kyrgyzstan into Kandahar AF in support of the Afghanistan NATO mission.

There has been debate regarding follow on orders for the C17, with the Air Force requesting line shutdown, and members of Congress attempting to reinstate production. Furthermore, in FY2007, the Air Force requested $1.6 billion to deal with what it termed "excessive combat use" on operational airframes.



Charactaristics

  • Crew: 3: 2 pilots, 1 loadmaster
  • Capacity: 102 troops or 36 litter and 54 ambulatory patients
  • Payload: 170,900 lb (77,519 kg) of cargo distributed at max over 18 463L master pallets or a mix of palletized cargo and vehicles
  • Length: 174 ft (53 m)
  • Wingspan: 169.8 ft (51.75 m)
  • Height: 55.1 ft (16.8 m)
  • Wing area: 3,800 ft² (353 m²)
  • Empty weight: 282,500 lb (128,100 kg)
  • Max takeoff weight: 585,000 lb (265,350 kg)
  • Powerplant: 4× Pratt & Whitney F117-PW-100 turbofans, 40,440 lbf (180 kN) each
  • Fuel capacity: 35,546 US gal (134,556 L)

Performance

  • Cruise speed: Mach 0.76 (450 knots, 515 mph, 830 km/h)
  • Range: 2,420 nmi[58] (2,785 mi, 4,482 km)
  • Service ceiling 45,000 ft (13,716 m)
  • Max wing loading: 150 lb/ft² (750 kg/m²)
  • Minimum thrust/weight: 0.277