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Determination of longitudinal aerodynamic derivatives using flight data from an icing research aircraftA flight test was performed with the NASA Lewis Research Center's DH-6 icing research aircraft. The purpose was to employ a flight test procedure and data analysis method, to determine the accuracy with which the effects of ice on aircraft stability and control could be measured. For simplicity, flight testing was restricted to the short period longitudinal mode. Two flights were flown in a clean (baseline) configuration, and two flights were flown with simulated horizontal tail ice. Forty-five repeat doublet maneuvers were performed in each of four test configurations, at a given trim speed, to determine the ensemble variation of the estimated stability and control derivatives. Additional maneuvers were also performed in each configuration, to determine the variation in the longitudinal derivative estimates over a wide range of trim speeds. Stability and control derivatives were estimated by a Modified Stepwise Regression (MSR) technique. A measure of the confidence in the derivative estimates was obtained by comparing the standard error for the ensemble of repeat maneuvers, to the average of the estimated standard errors predicted by the MSR program. A multiplicative relationship was determined between the ensemble standard error, and the averaged program standard errors. In addition, a 95 percent confidence interval analysis was performed for the elevator effectiveness estimates, C sub m sub delta e. This analysis identified the speed range where changes in C sub m sub delta e could be attributed to icing effects. The magnitude of icing effects on the derivative estimates were strongly dependent on flight speed and aircraft wing flap configuration. With wing flaps up, the estimated derivatives were degraded most at lower speeds corresponding to that configuration. With wing flaps extended to 10 degrees, the estimated derivatives were degraded most at the higher corresponding speeds. The effects of icing on the changes in longitudinal stability and control derivat
Document ID
19890041083
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Ranaudo, R. J.
(NASA Lewis Research Center Cleveland, OH, United States)
Reehorst, A. L.
(NASA Lewis Research Center Cleveland, OH, United States)
Bond, T. H.
(NASA Lewis Research Center Cleveland, OH, United States)
Batterson, J. G.
(NASA Langley Research Center Hampton, VA, United States)
O'Mara, T. M.
(NASA Langley Research Center Hampton, VA; George Washington University, Washington, DC, United States)
Date Acquired
August 14, 2013
Publication Date
January 1, 1989
Subject Category
Aircraft Stability And Control
Report/Patent Number
AIAA PAPER 89-0754
Accession Number
89A28454
Distribution Limits
Public
Copyright
Other

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