| 摘要 |
An aircraft for vertical or short take off and landing operations having two main lift nozzles, both positioned at or near the aircraft center of gravity utilizes one or more jet screen nozzles, arranged in a variety of shapes and combinations, discharging bypass air from a position forward of the center of gravity, and a variable pitch nozzle discharging engine exhaust gas mixed with bypass air from a position aft of the center of gravity, to achieve pitch control while airborne in vertical take off or landing mode. The jet screen nozzle also prevents or reduces ingestion of mixed hot exhaust gas and bypass air discharged through the main lift nozzles. The jet screen nozzle further prevents or reduces ingestion of foreign object debris disturbed by the vertical lift discharge flowing from the main lift nozzles. Lift improvement devices are deployed during short or vertical takeoff and landing operations to act as air dams to cause main lift nozzle discharge striking the ground and returning to the aircraft as a fountain flow and flowing against the lower surface of the aircraft, to separate from the aircraft surface and return toward the ground. This enhances lift effect on the aircraft while avoiding further hot exhaust gas flow along the aircraft skin surface and eventually into the aircraft engine inlet. A control system modulates the jet screen nozzle and aft pitch control nozzle, along with the cruise nozzle, main lift nozzles and other control nozzles so that total engine discharge flow area remains substantially constant through a range of pitch control and other maneuvering commands.
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