The McDonnell Douglas YC-15, like Boeing’s YC-14 prototype, had a high-set wing, fuselage blister fairings for the main landing gear units, and an upswept T-tail above the rear ramp/door arrangement. The primary difference between the two aircraft was the way each achieved STOL performance. Unlike the YC-14, the YC-15 wings were configured with sets of double-slotted flaps which could be extended downward directly into the jet flow from its four under-wing turbofan engines. Employing “under-surface blowing” to achieve STOL capability, part of the exhaust was directed downward by the flaps while the rest passed through and then downward over the flaps by means of the “Coanda Effect”.
Two YC-15s (#72-1875 and #72-1876) were built with two different size wingspans, 132 feet (40.42m) and 110 feet (33.6m), respectively. Both aircraft are 124 feet (37.86m) in length.
First flown on 26 August 1975, a 600-hour test program followed. Funding cuts eventually cancelled the AMST program in 1979. Both the YC-14 and the YC-15 satisfied the AMST performance requirements, which would later be incorporated into the design of the larger C-17 Globemaster III transport.
Returning to Service
In 1996, after more than 15 years in storage in the Arizona desert, the McDonnell Douglas YC-15 (N15YC / 72-1875) was being brought out of mothballs to continue its mission as an Advanced Technology Demonstrator (ATD). McDonnell Douglas Military Transport Aircraft, a division of Boeing, will be operating the YC-15 on an eight-year no-cost lease from the U.S. Air Force. It was the first Air Force developmental aircraft to be leased back to a contractor under a Cooperative Research and Development Agreement.
The primary reason for the agreement is to provide a prototype to explore new technology applications for the C-17 and other airlift aircraft. Boeing will pay all costs for refurbishment and testing. The government retains license to use for government purposes the technology developed. The contractor can obtain title to resulting technology for commercial use.
Using the YC-15 will reduce the risk and span time for developing and using new aircraft technologies for both the Air Force and Boeing. Some technologies will be directly related to the C-17 Globemaster III and some will affect possible future advanced airlift aircraft.
|Primary Role||STOL transport (prototype)|
|Original Contractor||McDonnell Douglas|
|Operator||United States Air Force|
|Wingspan||132 feet, 7 inches (40.42m)|
|Length||124 feet, 3 inches (37.86m)|
|Height at Tail||43 feet, 4 inches (13.18m)|
|Engines||Four Pratt & Whitney JT8D-17 turbofans|
|Thrust||16,000 pounds (71kN) per engine|
|Cruise Speed||543 mph (872km/h)|
|Max Speed||590 mph (949km/h)|
|Service Ceiling||30,000 feet (9,144m)|
|Operating Weight||117,400 lbs (53,252kg)|
|Max Payload (STOL)||27,000 lbs (12,247kg) @ 3Gs|
|Max Payload||62,000 lbs (28,128kg) @ 3Gs|
|Max Takeoff Weight (STOL)||154,568 lbs (70,111kg)|
|Max Takeoff Weight||216,680 lbs (98,284kg)|
|Takeoff/Landing Distances||Less than 2000 feet (610m)|
|Date Deployed||August 1975|