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Flight Investigation of Effects of Transition, Landing Approaches, Partial-Power Vertical Descents, and Droop-Stop Pounding on the Bending and Torsional Moments Encountered by a Helicopter Rotor BladeFlight tests have been conducted with a single-rotor helicopter, one blade of which was equipped at 14 percent and 40 percent of the blade radius with strain gages calibrated to measure moments rather than stresses, to determine the effects of transition, landing approaches, and partial-power vertical descents on the rotor-blade bending and torsional moments. In addition, ground tests were conducted to determine the effects of static droop-stop pounding on the rotor-blade moments. The results indicate that partial-power vertical descents and landing approaches produce rotor-blade moments that are higher than the moments encountered in any other flight condition investigated to date with this equipment. Decelerating through the transition region in level flight was found to result in higher vibratory moments than accelerating through this region. Deliberately induced static droop-stop pounding produced flapwise bending moments at the 14-percent-radius station which were as high as the moments experienced in landing approaches and partial-power vertical descents.
Document ID
19980228146
Acquisition Source
Headquarters
Document Type
Other - NASA Memorandum (MEMO)
Authors
Ludi, LeRoy H.
(NASA Langley Research Center Hampton, VA United States)
Date Acquired
September 6, 2013
Publication Date
May 1, 1959
Subject Category
Aircraft Design, Testing And Performance
Report/Patent Number
NASA-MEMO-5-7-59L
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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