C17 Globemaster Cargo Aircraft
April 5th, 2008
The Boeing (formerly McDonnell Douglas) C-17 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 C-17 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 C-17 takes its name from two previous United States cargo aircraft, the C-74 Globemaster and the C-124 Globemaster II.
In the 1970s, the US Air Force 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. Despite both entrants exceeding specified requirements, the AMST competition was canceled before a winner had been selected.
By the early 1980s, the USAF found itself with a large fleet of aging C-141 Starlifter cargo aircraft. Some of the C-141s 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 YC-15 as the basis. McDonnell Douglas was awarded a contract to build its proposed aircraft, by then designated the C-17A Globemaster III, on August 28, 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, freeing the C-5 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 1980s. Questions were also raised about more cost-effective alternatives during this time. In April 1990, Defense Secretary Richard Cheney reduced the order from 210 to 120 aircraft. The C-17's maiden flight was on September 15, 1991 from the McDonnell Douglas west coast plant in Long Beach, California, about a year behind schedule. This aircraft (T-1) 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 C-17 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 C-17 rather than in the C-5, Air Force and DoD studies from 1986 and 1991 had claimed that the C-17 could use 6,400 more runways (outside the US) than the C-5. It was later discovered that this study had only considered the runway dimensions, but not their strength or Load Classification Numbers (LCN). The C-5 has a lower LCN than the C-17, although the US Air Force places both in the same broad Load Classification Group (LCG). When considering runway dimensions and their load ratings, the C-17's worldwide runway advantage over the C-5 shrank from 6,400 to 911 airfields. However, the C-17's ability to use lower quality, austere airfields was not considered.
A January 1995 GAO report revealed that while the original C-17 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 C-17 was supposed to provide, feeling that the 42,000 lb (19,000 kg) capability of the C-130 Hercules was sufficient. It was decided not to conduct C-17 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 C-17 to meet its original airdrop requirements. A February 1997 GAO Report revealed that a C-17 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-1990s, most of the problems had been resolved. The first C-17 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, C-17A 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 C-17B production in 2010. The proposed C-17B would be capable of landing on sandy beaches and other areas off-limits to the C-17A.
On August 18, 2006 Boeing announced it was telling suppliers to stop work on parts for uncommitted C-17s. 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 21, a House and Senate conference committee approved a US$447 billion defense bill for 2007, that includes US$2.1 billion for 10 additional C-17s – which is seven more planes than either chamber originally approved in separate versions of their funding language. The additional purchase follows intense lobbying by Boeing, as well as by California state leaders (where the plane is manufactured), and Missouri leaders, where Boeing's defense business is based. However, this extends the life of the program for only one additional year, to 2010.
On March 2, 2007, Boeing announced the C-17 production line may end in mid-2009 due to the lack of additional US government and international orders.
A total of 190 C-17s are contracted for delivery to the USAF as of October 24, 2007. Efforts are underway to add a further 10 C-17s 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 C-17 can airlift such cargo close to a potential battle area.
The C-17 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 reduces the probability of foreign object damage and provides reverse thrust capable of backing the aircraft. Additionally, the C-17's thrust reversers can be used in flight at idle-reverse for added drag in maximum-rate descents.
The aircraft requires a crew of three (pilot, copilot, and loadmaster) for cargo operations. Cargo is loaded 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 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 using the sealed center wing bay as a fuel tank. These units are informally referred to by Boeing as the C-17 ER. The C-17 cruise speed is approximately 450 knots (833 km/h) (0.76 Mach). The C-17 is designed to airdrop 102 paratroopers and equipment.
The C-17 is designed to operate from runways as short as 3,500 ft (1,064 m) and as narrow as 90 ft (27 m). In addition, the C-17 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.
Boeing has actively marketed the C-17 to many European nations including Belgium, Germany, France, Italy, Spain and the United Kingdom. Of these, the UK was always seen as the most likely customer given its increasingly expeditionary military strategy and global commitments. The Royal Air Force has established an aim of having interoperability and some weapons and capabilities commonality with the United States Air Force. The UK's 1998 Strategic Defence Review identified a requirement for a strategic airlifter. The Short-Term Strategic Airlift (STSA) competition commenced in September of that year, however tendering was canceled in August 1999 with some bids identified by ministers as too expensive (including the Boeing/BAe C-17 bid) and others unsuitable. The project continued, with the C-17 seen as the favorite. The UK Defence Secretary, Geoff Hoon, announced in May 2000 that the RAF would lease four C-17s at an annual cost of £100 million from Boeing for an initial seven years with an optional two year extension. At this point the RAF would have the option to buy the aircraft or return them to Boeing. The UK committed to upgrading the C-17s in line with the USAF so that in the event of them being returned to Boeing the USAF could adopt them.
The first C-17 was delivered to the RAF at Boeing's Long Beach facility on May 17, 2001 and flown to RAF Brize Norton by a crew from No. 99 Squadron which had previously trained with USAF crews to gain competence on the type. The RAF's fourth C-17 was delivered on August 24, 2001. The RAF aircraft were some of the first to take advantage of the new center wing fuel tank.
The RAF declared itself delighted with the C-17 and reports began to emerge that they wished to retain the aircraft regardless of the A400M's progress. Although the C-17 fleet was to be a fallback for the A400M, the UK announced on July 21, 2004 that they have elected to buy their four C-17s at the end of the lease, even though the A400M is moving towards production. They will also be placing a follow-on order for one aircraft, though there may be additional purchases later. While the A400M is described as a "strategic" airlifter, the C-17 gives the RAF true strategic capabilities that it would not wish to lose, for example a maximum payload of 77,000 kg compared to the Airbus' 37,000 kg.
The Ministry of Defence (MoD) announced on August 4, 2006 that they had ordered an additional C-17 and that the four aircraft on lease will be purchased at the end of the current contract in 2008. The fifth aircraft was delivered on February 22, 2008. Due to fears that the A400M may suffer further delays, the MoD is planning to acquire three more C-17s (for a total of eight) for delivery in 2009-2010, provided that the U.S. Air Force places a follow-on order extending through the same time period. On July 26, 2007, Defence Secretary Des Browne announced that the MoD intends to order a sixth C-17 to boost operations in Iraq and Afghanistan. On December 3, 2007, the MoD announced a contract with Boeing for a sixth C-17 to be delivered in mid-2008.
In RAF service the C-17 has not been given an official designation (e.g. C-130J referred to as Hercules C4 or C5) due to its leased status, but is referred to simply as the C-17. Following the end of the lease period the four aircraft will assume an RAF designation, most likely "Globemaster C1".
