ON EVE OF SPACE TRAVEL

Press, Volume C, Issue 29554, 1 July 1961, Page 8

ON EVE OF SPACE TRAVEL

In this exclusive series of articles. Professor Hermann Oberth continues his summary of the past and present of rocket engineering, including his own first steps into this field His first series tt articles concluded in "The Press" on May 27 last. The present article is the first of the second series Professor Oberth was bom in 1834 in what was then Austro-Hungarian (later Rumanian) Transylvania, and in 1923 he laid the foundation of modern rocket research by bls book, "The Rocket Into Interplanetary Space." In 1930 he designed the first roeket engine for liquid oxygen, and the German V-2 rocket of World War II was based on his principles. Since the war he has participated in rocket resarch in the United States.'

Professor Hermann Oberth, in his second series of articles, continues his narrative of rocket engineering today. Leaving snch matters aside which are and have been the subject of numerous articles in newspapers and magazines, he concentrates on matters which he knows better than most experts in the field. His long experience of rocket engineering longer than nearly any other man's—and his personal way of describing his ideas give special interest to history.

Memories And Ideas Of A Rocket Genius (By PROFKSSOR HERMANN OBERTH) JJESPITE the very thorough checking of all parts and the application of the redundancy principle wherever possible, there have been many reports of failures in American take-offs; no doubt the proportion has been just as high in Russia. The only difference is that the Russians do not release any news about their failures. Anyway, because there have been so many unsuccessful take-offs, many people feel that it is irresponsible as yet to risk human lives in our present-day rockets. Space travel, thev say, should remain a subject for science fiction writers.

This may be a fair argument, but we are gradually learning how to make space rockets safe and reliable, just as we have learned to make safe and reliable automobiles. I use this comparison with automobile starts and only a very few rocket take-offs.

My answer is this: any engineering product may be developed intensively or extensively. The development of automobiles has been typically extensive: the development of rockets, on the other hand, has been intensive to the last degree. When a motor company prepares to put a new automobile in the

market, it will arrange a poll of salesmen and filling station supervisors to find out what the public prefers. Then a team of industrial designers will produce several drafts of types conforming to what is believed the public preference, after which a body of experts will congregate to discuss the shape, the profitableness, the market trend, etc., and finally the chief engineer will discuss the technical possibilities with his staff and will order ten to fifty designers to work out plans. Then five or 20 automobiles will be tested for three to six months by experienced test drivers. These and a staff of engineers will observe gas consumption, wear and tear, driving qualities, etc., after which the model will be put into mass production. The motor company seldom learns, if not in a Gallup poll, what experience the Smiths or the Jones's have had with their car. Customers with an inventing talent often even have difficulty in bringing possible suggestions for improvements to the knowledge of the manufacturer. Idea of New Brake. I can mention a case in point. Last spring a woman

in Germany wrote to me, telling me that she had the idea for a new brake which would not be worked with the foot but so that the driver would pull the steering wheel toward himself. For this reason he would have to have a safety belt but this could be no essential objection Seftey belts are prescribed in aeroplanes, and in some countries they are even now being made compulsory for motor drivers. The idea is downright brilliant It would surely save thousands of people anually from motor accidents. It is a natural reflex to pull at the steering wheel when you want to brake, and even the best-trained driver would react some tenths of a second faster by pulling the wheel than by pressing the foot on the brake pedal. The lattter will take place only after the end of the so-called “panic second," and a tenth of a second may mean all the difference between life and death. Despite all this, the woman who wrote to me had not been able to find any automobile factory where they would even listen to her!

Well, this was a parenthesis. I now come beck to rocket engineering as an intensive procedure ot development. In this type of engineering. a very small part is first subjected to thousands of tests and observations with scientific thoroughness.

The chemical properties of the fuel, the temperature of the combustion chamber, etc., are tested by experts. When finally the rocket is being fired on the test rack or when it lifts for actual

flight, hundreds of recordings are taken for continued study by thousands of engineers and scientists. The upshot of it all is that for every rocket flight a million times more data are recorded and collected than in the case of

an. automobile. It can therefore be safely hoped that in a few years liquid-fuelled rockets (this is now the most common type of propulsion) will be sufficiently safe to carry men and women into space. Apart from this, parachutes, oxygen suppliers, etc., are of course also constantly improved. Apart from liquidfuelled engines which require no external supply of oxydant, there are also those engines which take their oxygen from the air. They have been developed for turbo-jet and jet aeroplane engines and may now .be regarded as practically reliable. They are being considered today for the lower stages of soace rockets, since they would save 1200 tn./sec. in required thrust. At the same time experiments with solidfuelled rockets are advancing nicely. It is easily realised how reliable these may be from the fact that there is rarely a failure or an explosion in our common fireworks rockets, and this is one reason why powder, or solidfuel. rockets have continued to be used for the ttpner stages of space rockets. The question what type of rocket most likely to be used in the future cannot be answered sweepingly. It will largely depend on the purpose for which the rocket will be used in each particular case. There is no all-purpose rocket, just as there is hardly any stain remover which is equally efficient against juice stains or soots of rust. A turbine will work most efficiently when the liquid, steam or gas which makes it revolve, comes to a stop Immediately behind it. Similarly. a rocket works best when it is flying ahead just as fast as the gas flows out of it, so that the gas has no great speed after having done its job. Accordingly, air-fed engines are best for the lower stages, and solid fuel or so-called classic propellants for the middle stages, that is. liquid oxygen or hydrazine as oxydizer and water-mixed alcohol or hydrocarbons as fuel. For the upper stages, however, I would suggest hydrogen and fluorine, because these give by far the greatest exhaust speed. Today we need almost 1000 kg. of propellants for every kilo, gram of mass which is to be brought into space; if on the other hand, rockets were built following the suggestions here outlined, this relationship could be reduced to ten or 11. (To be Continued.)