| 摘要 |
A dual-configuration airfoil having a thin profile which is adapted to foster high-speed flight, and having a pivotable portion on the upper surface which is movable upwardly for selectively increasing the thickness of the airfoil. In one embodiment, the pivotable portion pivots about an axis which coincides generally with the leading edge of the airfoil. The thickness of the airfoil when the pivotable portion is fully raised is about twice the thickness of the airfoil when the pivotable portion is fully retracted. A rigid connecting section forms part of the airfoil's upper surface immediately behind the pivotable portion. The connecting section is also movable, such that a substantially continuous and rigid surface is presented to the air moving over the airfoil's upper surface during such times as the pivotable portion is being pivoted upward and downward-as well as when the pivotable portion is fixedly held. A rearwardly directed nozzle is located adjacent the aft edge of the pivotable portion, and it is oriented such that it can discharge a gaseous fluid (e.g., air) over the connecting section. A source of pressurized fluid, such as an engine-driven compressor or a fan, is adapted to be connected with said nozzle. And, a control or regulating valve is provided for adjusting the discharge of fluid from said source over the connecting section. Preferably, the connecting section is configured so as to cause the air which flows thereover to decelerate in a controlled manner, and preferably the deceleration occurs faster nearer the leading part of said section than near the trailing part thereof. In one embodiment, the means for adjusting the discharge of fluid from said nozzle includes a linkage which is connected to a movable control surface, such as a trailing edge flap. In this way, moving the flap down to a landing position can automatically cause fluid to be discharged from the nozzle and over a selected portion of the airfoil.
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