| 摘要 |
An air inlet and scoop for aircraft auxiliary power units to provide satisfactory performance thereof under all operational conditions, including full capability for in-flight starting at high altitudes, whereby operational difficulties caused by thick boundary layers and adverse pressure gradients between the inlet and the tail cone in the vicinity of the inlet are overcome. The inlet opening is contoured along its outer edges to conform to the aircraft fuselage and has a ramp trailing inwardly into the opening, starting at the fuselage and forming the bottom surface of the inlet. The inlet has generally parallel side walls trailing inwardly, the inlet side walls extending inwardly from the fuselage edges along the inlet opening. A scoop is hinged adjacent the fuselage at one end of the inlet opening, the aircraft having means therein to operate the scoop so as to open and close the inlet opening. The scoop has a closing wall surface with respect to the inlet opening, which when in the closed position is contoured to conform with the fuselage, the closing wall surface being continuous in the open and closed positions and generally limited to the extent of the inlet opening. The method of overcoming the problems of thickness of boundary layer and adverse pressure gradient between the inlet and tail cone in the vicinity of the inlet.
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