Abstract: 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.

Abstract: A predetermined-sized and shaped foil-fence structure which is substantially perpendicularly mounted at the foil-tip of a hydrofoil craft and projects downward, upward or partly downward and upward from the foil-tip. The fence surfaces are generally disposed parallel to the longitudinal axis of the craft.