YC-15 Military Transport

YC-15 prototype STOL military transportBuilt in response to an U.S. Air Force request for an Advanced Medium STOL (Short Takeoff and Landing) Transport (AMST), McDonnell Douglas built two YC-15 prototypes to replace the Lockheed C-130 Hercules tactical transport. They were to be used on short, undeveloped fields and Bell, Boeing, Fairchild, Lockheed and McDonnell Douglas submitted proposals in March 1972. Boeing and McDonnell Douglas won contracts to design and build the Boeing YC-14 and the McDonnell Douglas YC-15.

The YC-15 had four engines, while the Boeing version had two. The YC-15 used large double-slotted flaps that extended over 75 percent of the wingspan to enhance STOL capabilities. To save costs, it used a modified DC-8 nosewheel unit and the DC-10 cockpit, adapted for a two-person crew, with two lower windows for visibility during short-field landings.

It could hold 90 percent of all Army combat vehicles, including a 62,000-pound extended-barrel, 8-inch (203 mm) self-propelled howitzer. Vehicles were loaded through rear fuselage doors with built-in ramps. 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 Coanda effect. It was also the first military aircraft with a supercritical airfoil.

The YC-15 first flew on Aug. 26, 1975, and a competitive fly-off against its Boeing competitor was completed in 1977. However, the Air Force decided against the AMST aircraft and terminated the program. On Dec. 10, 1979, it formally cancelled the AMST program for both the YC-14 and the YC-15. This resulted in the development of the C-X (Cargo Transport Aircraft-Experimental) -- the future C-17.

The YC-15s were stored at the Military Aircraft and Disposition Center at Davis-Montham Air Force Base, Arizona. One was later loaned to the adjacent Pima Air Museum.

Specifications
First flight: Aug. 26, 1975
Model number: YC-15
Wingspan: 110 feet and 132 feet
Length: 124 feet
Height: 43 feet 4 inches
Gross weight: 219,180 pounds
Cruising speed: 535 mph
Range: 460 miles STOL with 27,000-pound payload; 2,292 miles conventional with 38,000-pound payload
Power plant: Four 15,500-pound-thrust Pratt & Whitney JT8D-209 Turbofan engines
Accommodation: Three crew, 150 troops or 27,000 pounds of cargo (STOL) or 69,000 pounds of cargo (conventional)