OTRAG Rocket.pdf

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ut it is quite another to launch a rocket, especially if one has so far been tested only single engines, and now 500 are fired at once. On the concept already existed in the 70's strong criticism. The DFVLR examined it and came to the conclusion that the financial success is questionable. With the technical approach is employed Prof. Ruppe. He came to the conclusion that to be too optimistic on the one hand the details of OTRAG and it is questionable whether it is technically feasible. Other experts complained numerous "white spots" in the concept, that is completely unresolved aspects of the support. Here are some personal considerations which must be assessed critically in this rocket. POGO effects Start No. 15 Photo 1The construction is very susceptible to POGO oscillations. POGO oscillations in rocket technology feared because they can not be simulated on the ground. Several rockets were suffering from the first flights under POGO oscillations, the Titan, Saturn V and the Ariane. Is caused by engine vibrations which are transferred to the tanks and bring the liquid to spill. This then amplifies the vibrations again so that it may in extreme cases to a fraction of the structure, as it happened in the second flight of the Ariane first This affects almost only first steps because they have very long tanks. In addition, the phenomenon usually occurs only after some time when the tanks are no longer full. Looking at the OTRAG rocket, so the tanks have a length of up to 24 m and a width of only 0.27 m. Representing a ratio of 80:1 means of length to width. In contrast, rocket stages, it is from 4:1 to 8:1. Furthermore, the tanks are already at the start only partially filled with fuel. Speaks against a vulnerable print promotion. There is no turbo pumps and portable engines, which come as sources of vibration in question. All tests which has made the OTRAG were relatively short modules (6 or 12 m length) instead. The shorter due to their length do not react quite as sensitive. It should also take into account that the tanks are very thin and, therefore, a break is easier. Kayser himself admits that the construction of long steps (18, 24 m) is only possible by pooling of many engines. Even without POGO oscillations otherwise the construction is not stiff enough. On the other hand, the rocket built entirely differently than other types and is constantly expanding the more modules are available. This can have an impact. It will probably be in the OTRAG rocket as with other missiles: for the first show for how the rocket behaves. The N-1 effect Start No. 15 2It image is a mistake to believe an engine, which we have extensively tested on the ground would be flight-qualified so automatically. The European space exploration has bitterly during initial launch of the Ariane 5 ECA experienced, not as the Vulcain 2 engine in flight withstand the pressures, although it was extensively tested on the ground before. Another improvement is the bundling of engines. Each engine also indirectly affects the
other. It transmits vibrations it gives off heat, it loads the structure. The best known example of the consequences is the Russian moon rocket N-1. Their engines have been tested extensively on the ground and were considered flight qualified. The block A, the first stage with 30 engines, but has no one tested as a whole, because it was the cost of a test stand of the enormous thrust force of 46000 kN has wanted to save. This took revenge. All four launches of the N-1 failed because of problems with the block A. OTRAG The rocket is the same problem: only here it is up to 500 engines are ignited at once. Unlike other missiles, it is not possible to test the engines before the start: After a test run, the ablation layer melted away and the engine scrap. A single test run on the ground of a 500 engine beam is thus quite expensive. Probably could not afford OTRAG also be capable of this test stand. (500 engines a takeoff thrust would result in up to 17 500 kN, 15 times more than have a test stand for the Vulcain engine of Ariane 5 start to load). Engine failure Start No. 15 Image 3Ein Another point concerns the effects of engine failure. In the experiments until 1974, there were 3 failures in 200 trials. Later, it was only known that there should have been more than 2,000 tests, but no success rate. 3 failures in 200 trials is a standard in rocketry size that I want to talk to include in the considerations. At first it seems a Triebwerksaufall a rocket with so many engines is critical. If only the loss of thrust, this is also unrestricted. What one should not forget: Since each 2 engines are attached to a common tank, remains on premature shutdown still a lot of fuel that is not used and then changed the full / empty mass ratio. In other missiles with multiple engines, you can catch the engine failure by the other can burn longer. This happened, for example, the mission of Apollo 13 when one of the engines turned out the second stage. This possibility OTRAG the rocket did not. For the 4 ton version with 256 engines, I have times the probability and consequences of an engine failure for a confidence just 99%. (A loss in 100 firings) The amendment to the empty weight is for the "worst case" scenario, that the engine failure immediately after the ignition: Level number engine failure probability of a change in idle speed changing mass loss of payload 1192 85.5% 4.7% -27 m / s -75 kg 2 48 38.3% 18.8% -97 m / s -260 kg 3 16 14.8% 56.3% -497 m / s -1350 kg Start No. 15 4Es image reveals the following: Although the failure of one engine in the first stage is relatively likely and should occur in virtually every mission, the impact is yet to begin. A cushion of 100 m / s, however, is today the exception rather rockets and a cushion of nearly 500 m / s corresponds to a reduction of the payload by a third. This means that the rocket OTRAG start with either a very large safety cushion needs, or
Page 1 and 2: OTRAG Rocket Introduction In this a
Page 3 and 4: Lutz Kayser was in addition to the
Page 5 and 6: • Reduce costs by using commercia
Page 7 and 8: denser than nitric acid and added a
Page 9 and 10: The engine has one line for the oxi
Page 11 and 12: opening is a thrust of 25 kN, the l
Page 13 and 14: The below average image that antici
Page 15 and 16: RohrfinnenDas engine is distinguish
Page 17 and 18: Diesel oil combustion support 220 k
Page 19 and 20: from each other by their diameter i
Page 21 and 22: OTRAG were to Lutz Kayser (CEO) Fra
Page 23 and 24: start Mobutu himself. Like most of
Page 25 and 26: optimize the parameters of a module
Page 27 and 28: 25% each for the activities in Zair
Page 29: Advantages of the concept The massi
Page 33 and 34: The whole thing is like comparing a
Page 35 and 36: ocket. They must be considered in t
Page 37 and 38: nozzle throat diameter is variable,
Page 40 and 41: © the text: Bernd Leitenberger. ©
Page 42: Space World, August / September 197

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