The Lockheed C-5 Galaxy is an American military transport aircraft built by Lockheed. It was designed to provide strategic heavy airlift over intercontinental distances and to carry outsize and oversize cargo. The C-5 Galaxy has been operated by the United States Air Force since 1969 and is one of the largest military aircraft in the world.
By late 1963, the next conceptual design was named CX-X. It was equipped with four engines, instead of six engines in the earlier CX-4 concept. The CX-X had a gross weight of , a maximum payload of and a speed of Mach 0.75 (). The cargo compartment was wide by high and long with front and rear access doors. In order to provide the required power and range with only four engines, a new engine with dramatically improved fuel economy would be needed.
The criteria were finalized and an official Request for Proposal was sent out in April 1964 for the "Heavy Logistics System" (CX-HLS) (previously CX-X). In May 1964, proposals for aircraft were received from Boeing, Douglas, General Dynamics, Lockheed, and Martin Marietta. Proposals for engines were received from General Electric, Curtiss-Wright Corporation, and Pratt & Whitney. After a downselect, Boeing, Douglas and Lockheed were given additional study contracts for the airframe, along with General Electric and Pratt and Whitney for the engines.
All three of the designs shared a number of features. In particular, all three placed the cockpit well above the cargo area so that in a crash the cargo would not crush the crew as it moved forward. The Boeing and Douglas designs used a "pod" on the top of the fuselage containing the cockpit, while the Lockheed design extended the cockpit line the length of the fuselage, giving it an egg-shaped cross section. All of the designs featured swept wings, T-tails, and front and rear cargo doors allowing simultaneous loading and unloading.
In 1965 Lockheed's aircraft design and General Electric's engine design were selected for the new transport.
The first C-5A Galaxy (number 66-8303) was rolled out of the manufacturing plant in Marietta, Georgia on March 2, 1968. On June 30, 1968 Lockheed-Georgia Co. began flight testing its new Galaxy C-5A heavy transport with the aircraft's first flight taking to the air under the call-sign "eight-three O three heavy".
Upon completion of testing the first C-5A was transferred to the Transitional Training Unit at Altus Air Force Base, OK, in December 1969. Lockheed then delivered the first operational Galaxy to the 437th Airlift Wing, Charleston Air Force Base, SC, in June 1970.
In the early 1970s, the C-5 was considered for the role of Shuttle Carrier Aircraft to transport the Space Shuttle to Kennedy Space Center by NASA, but rejected in favor of the Boeing 747 due in part to the 747's low-wing design. In contrast, the Soviet Union chose to transport its shuttles using the high-winged An-225, which is derived from the An-124, which is very similar to the C-5 in terms of design and function.
During static and fatigue testing, cracks in the wings occurred before completion of testing. All C-5A aircraft were restricted to 80% of maximum design loads. To reduce wing loading, load alleviation systems were added to the aircraft. By 1980, payloads were restricted to as low as for general cargo during peacetime operations. To restore full payload capability and service life, a program to rewing the 76 C-5As began in 1976. After design and testing of the new wing design, the C-5As received their new wings from 1980 to 1987.
The first C-5B was delivered to Altus Air Force Base in January 1986. In April 1989, the last of 50 C-5B aircraft was added to the 77 C-5As in the Air Force's airlift force structure. The C-5B includes all C-5A improvements and numerous additional system modifications to improve reliability and maintainability.
In 1998, the Avionics Modernization Program (AMP) began upgrading the C-5's avionics to include a glass cockpit, navigation equipment, and a new autopilot system. Another part of the C-5 modernization effort is the Reliability Enhancement and Re-engining Program (RERP). The program will mainly replace the engines with newer, more powerful ones. Three C-5s are to undergo RERP as a test with full production planned to begin in May 2008.
The C-5 is a large high-wing cargo aircraft. It has a distinctive high T-tail, 25 degree wing sweep, and four TF39 turbofan engines mounted on pylons beneath the wings. The C-5 is similar in appearance to its smaller predecessor, the C-141 Starlifter. The C-5 has 12 internal wing tanks and is equipped for aerial refueling. It has both nose and aft doors for "drive-through" loading and unloading of cargo.
The C-5 features a cargo compartment 121 feet long, 13.5 feet high, and 19 feet wide (37 m by 4.1 m by 5.8 m), or just over 31,000 ft³ (880 m³). The compartment can accommodate up to 36 463L master pallets or a mix of palletized cargo and vehicles. The cargo hold of the C-5 is actually a foot longer than the length of the first powered flight by the Wright Brothers' flyer at Kitty Hawk. The nose and aft doors open the full width and height of the cargo compartment to permit faster and easier loading. Ramps are full width at each end for loading double rows of vehicles. The volume of unusable space in a C-5's tail assembly (aft of the ramp) is larger than the available cargo space of a C-130 Hercules.
It has an upper deck seating area for 73 passengers. The passengers face the rear of the aircraft, rather than forward. Its take off and landing distances, at maximum gross weight, are 8,300 ft (2,530 m) and 4,900 ft (1,490 m) respectively. Its high flotation landing gear has 28 wheels to share the weight. The "kneeling" landing gear system permits lowering of the parked aircraft so the cargo floor is at truck-bed height to facilitate vehicle loading and unloading.
The C-5 has a MADAR (Malfunction Detection Analysis and Recording), a system that records and analyzes information and detects malfunctions in more than 800 test points. The C-5 is also known as "FRED" (Fucking Ridiculous Economic/Environmental Disaster) by its crews due to its maintenance/reliability issues and large consumption of fuel. The C-5 requires an average of 16 hours of maintenance for each flight hour based on 1996 data.
The Galaxy is capable of carrying nearly all of the Army's combat equipment, including bulky items such as the 74 ton armored vehicle launched bridge (AVLB), from the United States to any location on the globe.
The first C-5A was delivered to the USAF on 17 December 1969. Wings were built up in the early 1970s at Altus AFB, OK; Charleston AFB, Dover AFB, DE; and Travis AFB, CA. July 9, 1970 marked the C-5's first mission in Southeast Asia during the Vietnam War. Through the rest of the war, C-5s were used to transport equipment and troops. Equipment included Army tanks, and various aircraft. C-5s also delivered weapons and supplies to Israel as part of Operation Nickel Grass in 1973.
During the 1980s the C-5As were re-winged to restore full design capability. The US Air Force took delivery of the first C-5B on 28 December 1985 and the final one in April 1989.
Fourteen C-5As have been retired as of 2005. Aircraft number 69-0004 was the first, sent to the Warner-Robins Air Logistics Center (ALC) for tear down and inspection. Data from inspection will be used to evaluate structural integrity and estimate remaining fleet lifespan. Thirteen C-5As were sent to the Air Force's Aerospace Maintenance and Regeneration Center (AMARC) for inspection. At AMARC, 66-8306 underwent tear down and inspection similar to 69-0004 at WR-ALC. The remaining 12 will eventually be reclaimed as destructive inspection is performed on the airframes to test for corrosion and fatigue.
Sources have cited that the Air Force might be looking to replace some of these aircraft and have expressed interest in a military version of the new Airbus A380.
The C-5A is the original version of the C-5. From 1969 to 1973, 81 C-5As were delivered to US Air Forces bases. Due to cracks found in the wings in the mid-1970s, the cargo weight was restricted. To restore the plane's full capability, the wing structure was redesigned. A program to install new strengthened wings on 77 C-5As was conducted from 1981 to 1987. The redesigned wing made use of a new aluminum alloy that didn't exist during the original production.
Based on a recent study showing 80% of the C-5 airframe service life remaining, AMC began an aggressive program to modernize all remaining C-5Bs and C-5Cs and many of the C-5As. The C-5 Avionics Modernization Program (AMP) began in 1998 and includes upgrading avionics to Global Air Traffic Management compliance, improving communications, new flat panel displays, improving navigation and safety equipment, and installing a new autopilot system. The first flight of the first modified C-5 with AMP(85-0004) occurred on December 21, 2002.
Another part of the plan is a comprehensive Reliability Enhancement and Re-engining Program (RERP), which includes new General Electric CF6-80C2 engines, pylons and auxiliary power units, with upgrades to aircraft skin and frame, landing gear, cockpit and the pressurization system. The CF6 engine produces 22% more thrust (for a total of 54,000 lb (240 kN) from each engine) than existing C-5 engines which will result in a 30% shorter take-off roll, a 38% higher climb rate to initial altitude, a significantly increased cargo load, and a longer range between refueling. The C-5s that complete these upgrades are designated C-5M Super Galaxy.
The C-5 AMP and RERP modernization programs plan to raise mission-capable rate to a minimum goal of 75%. Over the next 40 years, the U.S. Air Force estimates the C-5M will save over US$20 billion. The first of 111 planned C-5M conversions was completed on May 16, 2006, and performed its first flight on June 19, 2006.
C-5Ms have been in flight testing out of Dobbins Air Reserve Base since June 2006. Two of the three (86-0013 and 86-0025) aircraft may be identified by the distinctive colored nose boom used to acquire test data. As of February 2008, the USAF will convert all remaining C-5Bs and C-5Cs into C-5M with avionics upgrades and re-engining. The C-5As will receive only the avionics upgrades.