F-15 MTD-STOL
The F-15 MTD – STOL (Maneuver Technology Demonstrator / Short Takeoff and Landing) is a version of F-15E Strike Eagle developed for NASA (National Aeronautics and Space Administration). It was first flown on September 7, 1988. This aircraft would later be used in the Intelligent Flight Control System programs from 1999 to 2008.
The aircraft is highly modified and is not representative of production F-15 aircraft. It was selected to serve as the research testbed for the S/MTD program because of the flexibility of its unique flight and propulsion control system.
External modifications to the aircraft included two canards mounted on the upper inlet area forward of the wing. The canards are modified F-18 horizontal tail surfaces. Additionally, the aircraft is equipped with a flight test nose boom configured with angle-of-attack and sideslip vanes and a total temperature probe.
The F-15 S/MTD is equipped with two F100-PW-200 turbofan engines (23,780 lbf (105.78 kN) each) which can vector up to 20 degrees off of the nominal engine thrust line in any direction.Pitch vectoring structural load limits were 6,000 pounds. The aircraft skin contour and structure in the aft fuselage area were modified to accommodate the larger size of the vectoring nozzle actuation system and to provide clearance for full 20 degree yaw vectoring.
The F-15 S/MTD flying qualities are significantly improved over production F-15 aircraft. Aircraft response is crisp and heavily damped throughout the research flight envelope. Subsonic roll rates are slightly reduced from production aircraft, but are still about 200 degrees per second at most flight conditions. In supersonic conditions, roll rates are higher than production aircraft. Roll coordination at all conditions is superior than production aircraft. Directional stability is enhanced by the canards and is approximately twice that of production aircraft at Mach 2.0. Stick forces in the landing pattern are somewhat higher than normal and there is a slight nose down rotation at touchdown to facilitate derotation for its former thrust reversing capability.
In-flight refueling is restricted to the KC-135 aircraft only using a test boom operator due to the limited clearance between the refueling boom and the left canard. In the refueling configuration, the canards are biased 8 degrees trailing edge down to provide increased clearance from the boom. The aircraft is typically refueled with the boom more extended than normal, with reduced lateral error tolerance, and lower than normal in elevation. Despite the limited refueling envelope, all the pilots agree that the aircraft has excellent handling qualities. Positional control on the boom is superb.
The F-15 S/MTD is now renamed to F-15 ACTIVE for NASA ACTIVE program. The ACTIVE test program is proving the maturity and reliability of the basic P/YBBN design.