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A Sequential Shifting Algorithm for Variable Rotor Speed ControlA proof of concept of a continuously variable rotor speed control methodology for rotorcraft is described. Variable rotor speed is desirable for several reasons including improved maneuverability, agility, and noise reduction. However, it has been difficult to implement because turboshaft engines are designed to operate within a narrow speed band, and a reliable drive train that can provide continuous power over a wide speed range does not exist. The new methodology proposed here is a sequential shifting control for twin-engine rotorcraft that coordinates the disengagement and engagement of the two turboshaft engines in such a way that the rotor speed may vary over a wide range, but the engines remain within their prescribed speed bands and provide continuous torque to the rotor; two multi-speed gearboxes facilitate the wide rotor speed variation. The shifting process begins when one engine slows down and disengages from the transmission by way of a standard freewheeling clutch mechanism; the other engine continues to apply torque to the rotor. Once one engine disengages, its gear shifts, the multi-speed gearbox output shaft speed resynchronizes and it re-engages. This process is then repeated with the other engine. By tailoring the sequential shifting, the rotor may perform large, rapid speed changes smoothly, as demonstrated in several examples. The emphasis of this effort is on the coordination and control aspects for proof of concept. The engines, rotor, and transmission are all simplified linear models, integrated to capture the basic dynamics of the problem.
Document ID
20070023675
Acquisition Source
Glenn Research Center
Document Type
Technical Memorandum (TM)
Authors
Litt, Jonathan S.
(Army Research Lab. Cleveland, OH, United States)
Edwards, Jason M.
(NASA Glenn Research Center Cleveland, OH, United States)
DeCastro, Jonathan A.
(ASRC Aerospace Corp. Cleveland, OH, United States)
Date Acquired
August 23, 2013
Publication Date
June 25, 2007
Subject Category
Aircraft Design, Testing And Performance
Report/Patent Number
NASA/TM-2007-214842
E-16058
ARL-TR-4086
Meeting Information
Meeting: AHS 63rd Annual Forum and Technology Display
Location: Virginia Beach, VA
Country: United States
Start Date: April 29, 2007
End Date: May 3, 2007
Sponsors: American Helicopter Society, Inc.
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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