Garnica

1

GENERAL BACKGROUND

1.1

INTRODUCTION

The subject of this book is the hypersonic airbreathing engine, a device that employs the enveloping atmosphere to propel aerospace vehicles at sustained speeds greatly in excess of the local speed of sound. This remarkable capability will complete the work on aviation begun by the Wright brothers in 1903 by making possible flight at virtually anyspeed and altitude, including the astounding prospect of escaping the sensible atmosphere of the Earth and coasting into a nearby permanent orbit. Perhaps more importantly for society, this will complete the shrinking of the planet that began with the jet age, that electrifying period of time in which the aircraft jet engine brought humankind together to an extent previously unimagined. Thepurpose of this chapter is to provide a setting for the technical material on hypersonic airbreathing engines, two types of which are ramjets and scramjets, that constitutes the remainder of the book. This chapter consists of roughly equal parts of historical background and a narrative description of the most important features of the hypersonic airbreathing engines themselves. For readers new to thefield, this information is meant to furnish the framework necessary to encourage and support further study. For readers experienced in the field, this information should indicate the level and tone of the approach, and may even provide some new insights. There are several references that are so fascinating and valuable that they are essential reading for anyone truly involved in this field. Theyare, in fact, so pertinent and rich that they axe recommended to anyone who wishes to be fully informed about the history and technology of hypersonic airbreathing flight. We have found them very useful, and they have helped to shape this book. The first of these is Ramjets, an AIAA Selected Reprint Series volume edited by Gordon L. Dugger of the Applied Physics Laboratory of the Johns HopkinsUniversity,1-1 an organization that has played a leading role throughout the development of ramjets and scramjets. This document reproduces 14 of the most important papers that had appeared by 1969, and contains a complementary bibliography of another 107 references arranged into six topical areas. It should also be noted that many of the selected reprints contain extensive bibliographies of their own.2

HYPERSONIC AIRBREATHING PROPULSION

A recent major and very impressive work is a two volume (1391 page) set on the history of hypersonic flight authored and edited by POchard P. Hallion and published by the Aeronautical Systems Division of the Wright-Patterson Air Force Base in 1987.1"2'1"3 Volume I is entitled The Hypersonic Revolution: From Max Valier to Project Prime, 1924-1967, andVolume II is entitled The Hypersonic Revolution: From Scramjet to the National Aero-Space Plane, 19641986. The special feature of these books is that they contain case studies written by top program managers describing the administration, planning, proposing, designing, and developing of several of the most important hypersonic systems of those times. The reader should therefore expect todiscover the organizational, financial, political, and personal, as well as the technological history of the field in these pages. There is also a substantial amount of interesting background information related to hypersonic airbreathing propulsion to be found in various periodicals, two of which will be cited here. First, many of the original or pioneering and now classical papers authored by theleading figures of hypersonics were published in the Journal of the Aerospace Sciences (earlier, Aeronautical Sciences). Perusing these volumes can be a rewarding and even an eye-opening experience. A thought-provoking yet typical example is the Twenty-First Wright Brothers Lecture, delivered by H. Julian Allen and entitled Hypersonic Flight and the Re-entry Problem.TM Second, many practical or...