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Development of an analytical method to predict helicopter main rotor performance in icing conditionsHistorically, certification of a helicopter for flight into known icing conditions was a problem. This is because of the current emphasis on flight testing for verification of system performance. Flight testing in icing conditions is difficult because, in addition to being dangerous and expensive, many times conditions which are sought after cannot be readily found in nature. The problem is compounded for helicopters because of their small range in comparison to many fixed wing aircraft. Thus, helicopters are forced to wait for conditions to occur in a certain region rather than seeking them out. These and other drawbacks to flight testing prompted extreme interest in developing validated alternatives to flight testing. One such alternative is theoretical prediction. It is desirable to have the ability to predict how a helicopter will perform when subjected to icing conditions. Herein, calculations are restricted to the main rotor, and are illustrated. The computational tool used to obtain performance is the lifting line analysis of B65. B65 incorporates experimental data into data banks in order to determine the section lift, drag, and moment characteristics of various airfoils at different Mach numbers and angles of attack. The local flow angle is calculated at user specified radial locations. This flow angle, along with the local Mach number is then cross referenced with the airfoil tables to obtain the local section characteristics. The local characteristics are then integrated together to obtain the entire rotor attributes. Once the clean performance is known, characterization of the type and shape of ice which accretes on the rotor blades is obtained using the analysis of LEWICE. The Interactive Boundary Layer (IBL) method then calculates the 2-D characteristics of the iced airfoil for input into the airfoil data bank of B65. Calculations are restricted to natural ice shedding and it is assumed that no de-icing takes place. Once the new lift, drag, and moment characteristics are known for the entire blade radius, this information is fed into B65, where the iced performance is then calculated.
Document ID
19920006749
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Britton, Randall K. (Sverdrup Technology, Inc. Brook Park, OH, United States)
Date Acquired
September 6, 2013
Publication Date
January 1, 1992
Subject Category
Aerodynamics
Report/Patent Number
NASA-CR-189110
AIAA PAPER 92-0418
NAS 1.26:189110
E-6779
Meeting Information
Meeting: Aerospace Sciences Meeting and Exhibit
Location: Reno, NV
Country: United States
Start Date: January 6, 1992
End Date: January 9, 1992
Sponsors: AIAA
Accession Number
92N15967
Funding Number(s)
CONTRACT_GRANT: NAS3-25266
PROJECT: RTOP 505-68-10
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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