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Some wake-related operational limitations of rotorcraftWind tunnel measurements show that the wake of a rotor, except at near hovering speeds, is not like that of a propeller. The wake is more like that of a wing except that, because of the slow speeds, the wake velocities may be much greater. The helicopter can produce a wake hazard to following light aircraft that is disproportionately great compared to an equivalent fixed wing aircraft. This hazard should be recognized by both pilots and airport controllers when operating in congested areas. Ground effect is generally counted as a blessing since it allows overloaded takeoffs; however, it also introduces additional operation problems. These problems include premature blade stall in hover, settling in forward transition, shuddering in approach to touchdown and complicatons with yaw control. Some of these problems were treated analytically in an approximate manner and reasonable experiment agreement was obtained. An awareness of these effects can prepare the user for their appearance and their consequences.
Document ID
19810007470
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Heyson, H. H. (NASA Langley Research Center Hampton, VA, United States)
Date Acquired
September 4, 2013
Publication Date
December 1, 1980
Subject Category
Aerodynamics
Report/Patent Number
NASA-TM-81920
Meeting Information
Meeting: Midwest Helicopter Safety Seminar
Location: Joliet, IL
Country: United States
Start Date: February 3, 1981
End Date: February 5, 1981
Sponsors: Illinois Dept. of Transportation, FAA
Accession Number
81N15985
Funding Number(s)
PROJECT: RTOP 505-01-13-02
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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