POWER PLANT FOR VERTICAL / SHORT TAKE-OFF AND SHORT LANDING AIRCRAFT

摘要

A propulsion system for use primarily in V/STOL aircraft is provided with a variable cycle, double bypass gas turbofan engine and a remote augmenter to produce auxiliary lift. The fan is oversized in air-pumping capability with respect to the cruise flight requirements of the remainder of the engine and a variable area, low pressure turbine is capable of supplying varying amounts of rotational energy to the oversized fan, thereby modulating its speed and pumping capability. During powered lift flight, the variable cycle engine is operated in the single bypass mode with the oversized fan at its maximum pumping capability. In this mode, substantially all of the bypass flow is routed as an auxiliary airstream to the remote augmenter where it is mixed with fuel, burned and exhausted through a vectorable nozzle to produce thrust for lifting. Additional lift is generated by the high energy products of combustion of the variable cycle engine which are further energized in an afterburner and exhausted through a thrust vectorable nozzle at the rear of the engine. In the cruise operating mode, the fan is driven at a slower rotational speed and all of the bypass flow is directed to a variable area bypass injector where it is mixed with the variable cycle engine products of combustion and exhausted as a mixture through the rear nozzle. The variable cycle engine can be selectively operated in the single or double bypass mode during cruise to maximize efficiency as the aircraft speed is varied. Because the total installed thrust is available in the forward cruise mode, an aircraft powered by the propulsion system of the present invention has substantially greater capabilities in the areas of excess power, acceleration time and combat ceiling when compared to prior art conceptions embodying separate lift plus lift/cruise engines. Additionally, by not having to develop and maintain a separate lift engine system, a substantially lower aircraft lift cycle cost is possible.