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Comparison of predicted and measured drag for a single-engine airplaneRenewed interest in natural laminar flow (NLF) has rekindled designers' concerns that manufacturing deviations, (loss of surface contours or other surface imperfections) may destroy the effectiveness of NLF for an operational airplane. This paper reports on experimental research that compares predicted and measured boundary layer transition, total drag, and two-dimensional drag coefficients for three different wing surface conditions on an airplane typical of general aviation manufacturing technology. The three flight test phases included: (1) assessment of an unpainted airframe, (2) flight tests of the same airplane after painstakingly filling and sanding the wings to design contours, and (3) similar measurements after this airplane was painted. In each flight phase, transition locations were monitored using either sublimating chemicals or pigmented oil. As expected, total drag changes were difficult to measure. Two-dimensional drag coefficients were estimated using the Eppler-Somers code and measured with a wake rake in a method very similar to Jones' pitot traverse method. The net change in two-dimensional drag was approximately 20 counts between the unpainted airplane and the 'hand-smoothed' airplane for typical cruise flight conditions.
Document ID
19860026229
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Ward, D. T.
(Texas A&M University College Station, United States)
Taylor, F. C.
(Texas A&M Univ. College Station, TX, United States)
Doo, J. T. P.
(Mooney Aircraft Corp. Kerrville, TX, United States)
Date Acquired
August 12, 2013
Publication Date
October 1, 1985
Subject Category
Aircraft Design, Testing And Performance
Report/Patent Number
AIAA PAPER 85-4038
Accession Number
86A10967
Funding Number(s)
CONTRACT_GRANT: NAG1-309
Distribution Limits
Public
Copyright
Other

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