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Aviation History
1951
1951 - 1326.PDF
KENNETH W. GATLAND FLIGHT, 13 July 1951 Part IV: The New Research Instrument Fig. 20. The WAC Corporal which, in 1945, reached 43^ miles. EVOLUTION of the GUIDED MISSILE THERE are applications other than the purely militaryfor which the rocket is eminently suited. As a meansof conducting research into the upper atmosphere, for example, it is unique because the thinning air which prevents small pilotless balloons from rising higher than approxi- mately 25 miles actually makes for improved rocket efficiency. Indeed, its characteristics are such that the rocket can extend its flight beyond the confines of the earth's atmospheric envelope into space. The new instrument has already reached a height of 242 miles and a step-vehicle under development, using the suc- cessful Viking rocket (Fig. 24) as a booster, is expected to climb higher than 350 miles. Research at present engaging the attention of scientists concerns cosmic radiation, the ionosphere, the spectrum of the sun, and measurements of pressure, temperature and composition of the upper atmosphere. In the United States opportunity is also taken to test the flight properties of rockets employed in this work. The first attempts to project recording instruments above the balloon limit were made with a small American-designed rocket known as the WAC Corporal (Fig. 20), and captured German A-4 (V-2) rockets which had been adapted to maintain a vertical path. The WAC Corporal was the outcome of research begun in 1944 at the Guggenheim Aeronautical Laboratory of the California Institute of Technology (GALCIT), as the result of a memorandum submitted to the Ordnance Department in November 1943 by Dr. von Karman, H. S. Tsien and Dr. F. J. Malina. Preliminary investigations began with the IN the first part of this article, in our issue of May 4th, theauthor discussed general aspects of his subject and re- viewed certain rocket-propelled ground-to-air missiles;Part II (May 18th) went on to discuss air-to-air missiles and rocket-driven intercepters. The third instalment(June 29th) reviewed the development programme carried out by the Germans with the A-4 ("V.2") rocket and its pro-jected derivatives. In the present part—and in the next instalment to follow—Mr. Gatland deals with the use ofrockets as instrument-carriers for high-altitude research. development of solid-propellent rockets to provide experi- mental data on the effect of sustained thrust on a missile stabilized by fixed fins, and to provide knowledge on*the use of launching boosters. The first missile, known as "Private A," was eight feet long, had a gross weight of more than 500 lb (including a 60-lb payload), and was powered by a solid rocket unit manufactured by the Aerojet Engineering Corporation and delivering a thrust of 1,000 lb for over 30 seconds. A booster rocket, comprising four standard 4^in aircraft R.P.s, supplied more than 21,500 lb thrust at take-off. The missile itself, which was designed for supersonic flight, had a sharp tapering nose and was stabilized at the after end by four fins. The launcher was a 36-ft long rectangular steel boom of "truss" type, with four internal guide rails, and was pivoted at its base both for lateral and vertical adjustment. Its func- tion was twofold : to support the missile and guide it on its course until a sufficient velocity was reached for it to be aerodynamically stable and, second, to allow the take-off booster to burn completely and to jettison before the missile cleared the launcher. The Private A was followed by another, basically similar, rocket but instead of the four symmetrical tail fins, it had one fin and two horizontal lifting surfaces with a total span of approximately 5ft; at the nose were two small stubby wings to act as trimmers. Although the subsequent tests of this winged rocket provided valuable data, they demon- strated clearly that to be wholly effective a missile with lifting surfaces requires inherent control equipment. It was directly as the result of preliminary research with the Private A that in December 1944 the Ordnance Depart- ment requested the Laboratory to investigate the practic- ability of a high-altitude rocket to carry 25 1b of meteoro- logical equipment to a height of at least 100,000ft (nearly 19 miles). A theoretical investigation indicated that the requested performance was possible and an experimental programme was initiated which included, among other specific tasks, the fabrication of a one-fifth scale-model of the proposed rocket; the latter was primarily to determine whether three tail fins would suffice instead of the usual four, and to check on the use of a booster. Firing tests of this model in July 1945 satisfactorily confirmed the design features. Fig. 21. U.S. high-altitude research with captured German A-4s began in 1946 and, later, the warhead space was used for instrumentation.
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