the stall/spin resistance speed obtained, resulting in some loss of cruise airspeed, although sometimes too small "to be detected with production instruments". In the case of the best wing modification of the AA-1 Yankee, the loss of cruise speed amounted to 2 mph or 2% and there was no speed loss in climb. Impact on cruise speed of the Piper PA-28 RX (modified T-tail) was not measurable. For the Questair Venture, "In carefully controlled performance tests, the penalty in cruise performance was found to be imperceptible (1 kt)". Applications The first use of outboard cuffs, other than on NASA research airplanes, was on the Rutan VariEze in 1978. They were wind tunnel tested in 1982, and later (1984) replaced by vortilons. Following aircraft were modified for experiments with the addition of an outboard leading-edge cuff as a result of NASA stall/spin research program : Grumman American AA-1X (1978) Beechcraft C-23X (1980) Piper PA28 RX modified (T-tail) (1981) Cessna 172X (1983), Verilite Sunbird, high-wing pusher (1986) Questair Venture Cessna 210 (1987), high wing aspect ratio, Smith Trainer (1992) Leading-edge cuffs are used on 1900s high-performance light aircraft like the Cirrus SR20 and Columbia 350, which both gained FAA-certification with the device. Several after-market suppliers of STOL kits make use of leading-edge cuffs, in some cases in conjunction with such other aerodynamic devices as wing fences and drooping ailerons. See also Leading-edge droop flap Leading-edge slat Strake (aeronautics) References External links Wing Vortex Devices Aircraft wing components Aircraft wing design