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The Thrust Augmentation of Rocket Motors at High Altitudes*

Published online by Cambridge University Press:  04 July 2016

D. J. Harper*
Affiliation:
Formerly Royal Aircraft Establishment, Farnborough, now on loan to the Central Scientific Staff, Ministry of Defence

Summary

Rocket motors designed for operation in ground launched vehicles generally have nozzle expansion ratios giving optimum thrust at low altitude (about 20 000ft). At higher altitudes the jets are under-expanded and the thrust is less than the maximum available with nozzles of higher expansion ratio. Some of this lost thrust may be regained by suitable design of the propulsion bay geometry, without the low altitude disadvantages of high expansion ratio nozzles. In addition, where the vehicle is propelled by clustered motors, interaction between the jet effluxes at high altitudes can be used to develop an extra thrust acting on the base of the vehicle. The flow changes, from low to high altitude, leading to these effects are described.

The results of the first firings of Black Knight drew attention in this country to these effects. Model tests in both the U.K. and America have confirmed them and indicated various means by which the thrust of clustered rockets may be augmented; these are described and consideration is also given to the side effects of thrust augmentation on vehicle control and propulsion bay heating. A full scale experiment, planned for the end of 1962 is outlined and possible future applications are considered.

Type
Research Article
Copyright
Copyright © Royal Aeronautical Society 1964

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Footnotes

*

One of the papers given at the Second Rocket Propulsion Symposium held jointly by the Society, the College of Aeronautics and the British Interplanetary Society on 26th-27th April 1962 at Cranfield. Some of the papers are to be published by the B.I.S. and six by the R.Ae.S. The first four were published in the November 1964 Journal.

References

1.Henderson, L. F. The Impingement of a Supersonic Jet on a Flat Plate. Note ARL/ME.238, February 1960. Aero nautical Research Laboratories, Melbourne, Australia.Google Scholar
2.Goethert, B. H. Base Flow Characteristics of Missiles with Cluster-Rocket Exhausts. I.A.S. Paper No. 60-89. Presented at the Institute of Aeronautical Sciences Meeting, Los Angeles, California, 28th June-lst July 1960.Google Scholar
3.Coy, J. D. C. and Ricketson, B. W. A. Pumping by Gas Solidification—A Cryogenic Pump. Rocket Propulsion Establishment Tech. Note No. 209, October 1961.Google Scholar
4.Cornford, E. C.A British Space Booster. The Aeroplane pp. 186188, 12th August 1960.Google Scholar