Abstract: An aircraft bypass turbofan engine subassembly for ground deceleration (e.g., thrust reversal). A fan nacelle has a through passageway connecting its inner exterior surface and outer exterior surface. A passageway end is located on the inner exterior surface aft of the aft-most row of fan rotor blades. A row of pivotable fan outlet guide vanes is located radially between the fan and core nacelles and longitudinally aft of the flow splitter and the passageway end. Apparatus is provided to pivot the vanes to block passage of bypass air and to open the passageway for ground deceleration.

Abstract: A method of operating an aircraft bypass turbofan engine having variable fan outlet guide vanes. In a first embodiment, an engine out condition is sensed, fan rotor speed is repeatedly measured, and vane pitch is adjusted to a predetermined value as a function of the fan rotor speed to generally maximize airflow through the vanes during the engine out condition. In a second embodiment, vane pitch is adjusted to a preselected value as a function of fan rotor speed to generally minimize engine noise during a noise reduction mode of engine operation.

Abstract: A compact apparatus for simulating the in-flight aerodynamic performance of a multimission aircraft propulsion system of the gas turbine engine variety having an external envelope of a reduced size in relation to the engine to be simulated. The apparatus includes a turbine driven by externally generated, high pressure motive air which is drivingly connected to a compressor in the usual manner of a gas turbine engine. The flow of air pressurized by the compressor is mixed with a portion of the relatively higher pressure turbine motive air so as to generate a mixed flow having a generally uniform pressure profile entering the exhaust nozzle. The compressor, turbine, mixer and nozzle are sized to produce a pressure ratio across the apparatus and a nozzle flow function which are substantially identical to the engine to be simulated, though these components are of a reduced size in relation thereto.