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An Investigation in the Ames 40- by 80-Foot Wind Tunnel of a YT-56A Turboprop Engine Incorporating a Decoupler and a Controlled-Feathering DeviceAn investigation of a decoupler and a controlled-feathering device incorporated with the YT-56A turboprop engine has been made to determine the effectiveness of these devices in reducing the high negative thrust (drag) which accompanies power failure of this type of engine. Power failures were simulated by fuel cut-off, both without either device free to operate, and with each device free to operate singly. The investigation was made through an airspeed range from 50 to 230 mph. It was found that with neither device free to operate, the drag levels realized after power failures at airspeeds above 170 mph would impose vertical tail loads higher than those allowable for the YC-130, the airplane for which the test power package was designed. These levels were reached in approximately one second. The maximum drag realized after power failure was not appreciably altered by the use of the decoupler although the decoupler did put a limit on the duration of the peak drag. The controlled-feathering device maintained a level of essentially zero drag after power failure. The use of the decoupler in the YT-56A engine complicates windmilling air-starting procedures and makes it necessary to place operating restrictions on the engine to assure safe flight at low-power conditions,
Document ID
20050019274
Acquisition Source
Langley Research Center
Document Type
Other - NACA Research Memorandum
Authors
Rogallo, Vernon L. (National Advisory Committee for Aeronautics. Ames Aeronautical Lab. Moffett Field, CA, United States)
Yaggy, Paul F. (National Advisory Committee for Aeronautics. Ames Aeronautical Lab. Moffett Field, CA, United States)
McCloud, John L., III (National Advisory Committee for Aeronautics. Ames Aeronautical Lab. Moffett Field, CA, United States)
Date Acquired
August 22, 2013
Publication Date
September 9, 1954
Subject Category
Aircraft Propulsion And Power
Report/Patent Number
NACA-RM-SA54I09
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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