McDonnell Douglas YC-15

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The YC-15 was McDonnell Douglas's entry into the USAF's Advanced Medium STOL Transport (AMST) competition, to replace the C-130 Hercules as the USAF's standard STOL tactical transport.

The USAF issued a request for proposals in 1972 and in 1973 awarded contracts to McDonnell Douglas and Boeing for two prototypes each under the designations YC-15 and YC-14, respectively. The YC-15 introduced a number of innovative features, such as externally blown flaps, which used double-slotted flaps to direct part of the jet exhaust downwards, while the rest of the exhaust passed through and downward over the flaps, introducing the Coandă effect. It was also the first military aircraft with a supercritical airfoil.

The YC-15, as well as the YC-14, met or exceeded the specifications of the contest. However, the project was cancelled before either product could be chosen. The YC-15 would see a new life when it was developed into the highly successful C-17 Globemaster III, which included several YC-15 innovations, including the externally blown flaps and supercritical airfoil.

Two YC-15s were built, one with a wingspan of 110 feet (#72-1876) and one with 132 feet (#72-1875). Both were 124 feet long and powered by four Pratt & Whitney JT8D-17 engines, each with 15,500 lbf (68.9 kN) thrust. The first flight was August 26, 1975. The YC-15s completed a 600 hour flight test program in 1977. The AMST program ws canceled in 1979.

After the flight test program, the two aircraft were stored at the AMARC. located at Davis-Monthan Air Force Base. One was subsequently displayed at the nearby Pima Air & Space Museum. #72-1875 was returned to flying status by McDonnell Douglas in 1996. This aircraft resumed flying in April 1997. The intention was to use the YC-15 to evaluate new technology for advanced tactical transports. After an engine failed, the aircraft was deemed too expensive to repair and was returned to storage.

[edit] Specifications

General characteristics

Crew: 3
Capacity: Up to 150 troops or 78,000 lb of cargo
Length: 124 ft 3 in (37.9 m)
Wingspan: 110 ft 4 in/132 ft 7 in (33.6 m/40.4 m)
Height: 43 ft 4 in (13.2 m)
Wing area: 1,740 ft² (162 m²)
Empty weight: 105,000 lb (47,600 kg)
Max takeoff weight: 219,200 lb (99,400 kg)
Powerplant: 4× Pratt & Whitney JT8D-17 turbofans, 15,500 lb_f (68,9 kN) each