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Tests of a Gust-Alleviating Flap in the Gust Tunnel*

Published online by Cambridge University Press:  28 July 2016

Philip Donely  and
C. C. Shufflebarger
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Summary

Tests were made in the N.A.C.A. gust tunnel to determine the effectiveness of a long-period dynamically overbalanced flap in reducing aeroplane accelerations due to atmospheric gusts. For two gust shapes, one gust velocity, one forward velocity, and one wing loading, a series of flights was made with the flap locked and was then repeated with the flap free to operate. The records obtained were evaluated by routine methods.

The results indicate that the flap reduced the maximum acceleration increment 39 per cent, for a severe gust with a representative gust gradient distance of 8 chord lengths and that, for an extreme gust shape (a sharp-edge gust), the reduction was only 3 per cent. The results also indicate that the flap tended to reduce the longitudinal stability of the aeroplane. Computations made of the effectiveness and the action of the flap were in good agreement with the experimental results.

Type
Research Article
Information
The Aeronautical Journal , Volume 44 , Issue 351 , March 1940 , pp. 283 - 294
Copyright
Copyright © Royal Aeronautical Society 1940

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Footnotes

*

Reprinted by courteous permission of the National Advisory Committee for Aeronautics.

References

1. Donely, Philip. An Experimental Investigation of the Normal Acceleration of an Airplane Model in a Gust. T.N. No. 706, N.A.C.A., 1939.Google Scholar
2. Theodorsen, Theodore. General Theory of Aerodynamic Instability and the Mechanism of Flutter. T.R. No. 496, N.A.C.A., 1935.Google Scholar
3. Wenzinger, Carl J. Wind-Tunnel Investigation of Ordinary and Split Flaps on Airfoils of Different Profile. T.R. No. 554, N.A.C.A., 1936.Google Scholar
4. Rhode, Richard V. Gust Loads on Airplanes. S.A.E. Trans., Vol. 32, 1937, pp. 81–88.Google Scholar
5. Garrick, I. E. On Some Reciprocal Relations in the Theory of Non-stationary Flows. T.R. No. 629, N.A.C.A., 1938.Google Scholar