GB639125A - Improvements in or relating to aircraft - Google Patents

Abstract

639,125. Boundary layer control. STALKER, E. A. Oct. 16, 1946, No. 30800. Convention date, Aug. 16, 1941. [Class 4] An aircraft comprises a lift flap and a blower for inducing air from the boundary layer through a slot in the wing, the blower being driven by a pusher propeller adapted to act as a windmill during landing and at low aircraft speeds, the propeller being spaced from the trailing edge of the wing a distance greater than one-third and preferably one-half of the propeller diameter whereby the wing, when the propeller is windmilling, is out of effective range of the propeller, but remains subject to the full velocity of the relative wind across its surface so that substantially normal lift distribution results along the wing span. Figs. 1 and 2 show an arrangement in which the propeller 7 is mounted at the rear of the fuselage 2 between tail booms 4, and is driven by an engine 6 which also drives a blower 10 through a shaft 8. Boundary layer air is sucked through slots 13 in the upper wing surface and discharged through further slots 14 disposed near the leading edge. The engine transmission includes a one-way clutch to enable the blower to be driven by the propeller when windmilling. In the arrangement shown in Fig. 7, twin propellers 7 are driven by a single engine 6 through shafting 25 and bevel gearing 19, one-way clutches being provided in the transmission. The blower 28 sucks in boundary layer air through slots 27 and discharges it through slots 29.