Comparison of Flight and Wind-Tunnel Measurements of High-Speed-Airplane Stability and Control Characteristics

Williams, Walter C. and Drake, Hubert M. and Fischel, Jack (1956) Comparison of Flight and Wind-Tunnel Measurements of High-Speed-Airplane Stability and Control Characteristics. Technical Report NACA TN 3859, Research Engineering, NASA Dryden Flight Research Center.

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Abstract

Comparisons of wind-tunnel and flight-measured values of stability and control characteristics are of considerable interest to the designer, since the wind-tunnel method of testing is one of the prime sources upon which estimates of the characteristics of a new configuration are based. In this paper, comparisons are made of some of the more important stability and control characteristics of three swept-wing airplanes as measured in flight and in wind tunnels. Wind-tunnel data from high-speed closed-throat tunnels, a slotted-throat transonic tunnel, and a supersonic tunnel are used. The comparisons show that, generally speaking, the wind tunnels predict all trends of characteristics reasonably well. There are, however, differences in exact values of parameters, which could be attributed somewhat to differences in the model caused by the method of support. The small size of the models may have some effect on measurements of flap effectiveness. When nonlinearities in derivatives occur during wind-tunnel tests, additional data should be obtained in the region of the nonlinearities in order to predict more accurately the flight characteristics. Also, nonlinearities in static derivatives must be analyzed on the basis of dynamic motions of the airplane. Aeroelastic corrections must be made to wind-tunnel data for models of airplanes which have thin surfaces and are to be flown at high dynamic pressures. Inlet effects can exert an influence on the characteristics, depending upon air requirements of the engine and location of the inlets.

EPrint Type:	NACA Report
Subjects:	Aircraft/Project: Miscellaneous (01 - 09) Aeronautics: (08) Aircraft Stability And Control NACA Publication
ID Code:	926
Deposited On:	02 June 2006
Additional Information:	17 pages.