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The effect of trailing-edge strips on the unsteady aerodynamic forces on a control surface

Published online by Cambridge University Press:  04 July 2016

G. Long
Affiliation:
Aeronautical Research Laboratories, Melbourne
P. A. Farrell
Affiliation:
Aeronautical Research Laboratories, Melbourne

Extract

A modification sometimes used to increase the effectiveness of a control surface is thickening of the trailing-edge by attaching small spanwise strips, normal to the upper and lower surface of the control, along the trailing-edge (see Fig. 1). While the effect of such a modification is fairly well known for steady flow, little evidence is available of the effect in unsteady flow. There are no theoretical methods of predicting the unsteady aerodynamic forces acting on an oscillating control surface which has trailing-edge strips (T-strips) attached and so flutter calculations are based on classical thin-liftingsurface theories. This practice is very dubious and two instances where flutter has occurred but has not been predicted by use of the classical unsteady aerodynamic forces, are described in Refs. 2 and 3.

Type
Technical Notes
Copyright
Copyright © Royal Aeronautical Society 1980 

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References

1. Broadbent, E. G. The elementary theory of aeroelasticity. Aircraft Engineering, March-June 1954.Google Scholar
2. Niblett, L. T. Flutter calculations on a rudder with trailing-edge spoiler. RAE report Structures 202, May 1956.Google Scholar
3. Report on investigation of tailplane flutter GAF N24 Nomad aircraft at Avalon, Victoria on 6th August 1976. Dept of Transport, Australia. Special Investigation Report 77-1.Google Scholar
4. Farrell, P. A. A Fortran program to calculate twodimensional subsonic oscillatory aerodynamic forces, based on doublet lines. ARL Memo, to be published.Google Scholar
5. Tijdeman, H. and Berg, H. Analysis of pressure distribution on a wing with oscillating control surface in twodimensional high subsonic and transonic flow. NLR TR F253, 1969.Google Scholar