WIND TUNNEL TESTS OF A FREE-WING TILT-PROPELLER V/STOL AIRPLANE MODEL
Technical rept. Jun 1968-Aug 1969
AIR VEHICLE CORP SAN DIEGO CA
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Wind tunnel tests were conducted on a free-wing tilt-propeller VSTOL airplane model to investigate the aerodynamic characteristics of the free- floating wing in the propeller slipstream through the transitional region from cruise to near hover. Lift and drag curves wing-free were obtained as a function of propeller tilt angle and thrust coefficient, and are compared with wing-pinned data. The results indicate that the tilted propeller does not significantly turn the flow past the wing, except at thrust coefficients near unity and at propeller tilt angles near 90 deg. It is found that lift curve slope and maximum lift coefficient are strong functions of thrust coefficient. Provided the cruise static margin is adequate, the free-floating wing with flap and slat retracted behaves in the slipstream with no unusual problems. Based upon these initial test results, the free-wing concept therefore appears to be feasible aerodynamically. Additional wind tunnel tests are required on the free wing with flap and slat extended.