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An Investigation of Lifting Effects on the Intensity of Sonic Booms*

Published online by Cambridge University Press:  04 July 2016

John Morris
John Morris*
Affiliation:
formerly Group Engineer, Transport Division, Boeing Airplane Company; now Advanced Projects Group, Hawker Siddeley Aviation Ltd.
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Summary

This paper is a brief summary of an investigation made to check the effect of lift on the shock noise of aircraft flying at supersonic speeds. The method of Hayes has been combined with the theory of Whitham to predict the asymptotic shock strength of wings carrying lift and of combinations of bodies and lifting wings. (A similar, but not quite as general, method was derived by Walkden in Ref. 6.) Whitham's formula, including only the volume term, has been used extensively to predict the boom intensity of aeroplane type bodies and the agreement with experiment has, so far, been quite reasonable. The test data obtained to date extends only up to about 40,000 ft. altitude and the calculations of this paper show that under those conditions the shock noise of the aircraft tested so far will, in most cases, be dominated by the volume term. It is shown that at higher altitudes lifting effects will dominate for even the small fighter and they will dominate over most of the altitude range for large bomber and supersonic transport aircraft. The boom intensity due to lift decreases with altitude as h–¾ which compares to pa½ h–¾ in the volume case (pa = pressure at altitude h). It is insensitive to Mach number (for M > 1·4), wing loading, wing plan shape and lift distribution. A simple rule for calculating the shock noise due to combined volume and lifting effects is proposed which is applicable to configurations with wings located towards the rear of the fuselage. The rule states that the shock noise of an aircraft carrying lift is equal to the shock noise due to volume (neglecting lift) or the shock noise due to lift (neglecting volume), whichever is the greater. A chart is presented from which rapid estimates can be made of the shock noise of lifting wing-body combinations.

Type
Research Article
Information
The Aeronautical Journal , Volume 64 , Issue 598 , October 1960 , pp. 610 - 616
Copyright
Copyright © Royal Aeronautical Society 1960

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Footnotes

*

This paper is a slightly modified version of Ref. 5.

References

1.Maglieri, Domenic J. and Carlson, Harry W. (1959). The Shock-Wave Noise Problem of Supersonic Aircraft in Steady Flight. N.A.C.A. Memo 3-4-59L, April 1959.Google Scholar
2.Whitham, G. B. (1952). The Flow Pattern of a Supersonic Projectile, Comm. on Pure and Applied Math., Vol. V, No. 3, August 1952.Google Scholar
3.Hayes, Wallace D. (1947). Linearized Supersonic Flow. North American Aviation Report AL No. 222, June 1947.Google Scholar
4.Jones, Robert T. (1956). Theory of Wing-Body Drag at Supersonic Speeds. N.A.C.A. Report 1284, 1956.Google Scholar
5.Morris, John (1959). An Investigation of Lifting Effects on the Intensity of Sonic Booms. Boeing Report D6-3653, June 1959.Google Scholar
6.Walkden, F. (1958). The Shock Pattern of a Wing-Body Combination, Far From the Flight Path. The Aeronautical Quarterly, Vol. IX, pp. 164–194, May 1958.Google Scholar