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Aviation History
1989
1989 - 0416.PDF
The Soviet space union In the 1990s the Soviet Union will be operating a booster capable of lifting 100 tonnes into low Earth orbit, and a space shuttle able to return 20-tonne pay- loads to Earth. Together, the Energia booster and Buran shuttle will deliver and replace Mir 1 space station modules and assemble Mir 2, with its 100-tonne core module, five times larger than that of Mir 1. The Soviets have this capability and the USA does not (and is unlikely to until later in the 1990s), because Energia was designed independently of Buran, which, without its own launch engines, is just one of a variety of payloads that can be carried by the booster. The US Shuttle external tank and solid- rocket booster stack is not a separate launch system. Engines from the Orbiter itself, and much work, will be needed to produce the Shuttle C unmanned cargo vehicle. Energia Energia illustrates the typical Soviet approach to booster development. Stages are stacked together, just as they were on the first ICBM, which was also the Sputnik 1 launcher, in 1957. It may not look exactly sophisticated, but it is purely functional, and it works. The Soviets attempted to build a large, 4,500-tonne-thrust booster in the 1960s, as part of the manned lunar flight programme, but failed to get to the Moon first. The G Booster, or SL-15 as it was desig nated in the West, a huge stack of stages clamped together, performed three spec tacular failures before being scrapped in the early 1970s. Work on Energia began in 1978, at about the same time as Buran. The military services were a major influence. It was origi nally designed to place 102 tonnes into low Earth orbit (LEO), with the capability to be upgraded, possibly to place up to 180 tonnes into LEO on a single launch. Western analysts expected Energia to fly in the early 1980s, but it was not ready until May 15, 1987. This model, designated the SL-17 in the West, comprised a core stage, four strap- on boosters, and a piggyback "upper stage", to achieve orbital velocity. With a total sea- level thrust of 3,500 tonnes, Energia is the world's most powerful booster, surpassing America's Saturn 5, which last flew in 1973. The US Space Shuttle, the Soviets admit, "got under our skins". The result, predictably is a Soviet shuttle, but one that is part of a larger system including a heavy- lift booster and long-stay space station. Tim Furniss reports. The 59m-tall, 8m-diameter core stage incorporates the first Soviet rocket engines to burn cryogenic propellants, and also the first to fly on a first stage of a conventional launcher. The latter is the greatest achieve ment, because the engines came many years after similar engines had flown on US, Euro pean, Japanese, and Chinese vehicles. The stage is built from new materials such as high strength "progressive pulsed steel and alumi nium alloys, arc and electron-beam welded," the Soviets say. The four unnamed engines provide a total vacuum thrust of 800 tonnes. An analysis by Western expert Phil Clark of Commercial Space Technologies of the UK suggests that these engines consume about 820 tonnes of liquid oxygen and liquid hydrogen. The dry weight of the core stage is about 85 tonnes. The four non-throttleable engines ignite an instant before lift-off and burn for about 480 seconds before cut-off at 110km altitude. Energia's computers monitor and control more than 2,000 parameters, and have been programmed to deal with 500 contingencies, many of which have been tested during pad static test firings of "virtually" the full duration, the Soviets say. Launch azimuth is controlled by "electrohydraulic, 30-tonne- force engine gimballing, with an accuracy of 1 per cent of the range of movement". The core possibly separates into three parts (it is transported to Baikonur as three components), which coast for about 30min before re-entering the Earth's atmosphere over the Pacific Ocean. Former cosmonaut Lt Gen Gherman Titov, now with the Soviet ministry of defence, tells Flight that the stage is destroyed, and that there are no plans to protect, retrieve, and reuse parts of it, such as the valuable engines. However, other Soviet officials say that the engines have a "long life" (which may only refer to the burn time) and are "reusable", suggesting they may be recovered in a landing "pod". This is unlikely to happen for many years, if at all. The four strap-on boosters on the basic Energia are based on the first stage of the SL-16 medium-lift launch vehicle. This had made 13 flights to the end of 1988, and can place 12 tonnes into LEO, according to Soviet officials, although 15 tonnes has been suggested by Western analysts. The boosters are 38m long and of 4m diameter, giving Energia a maximum diameter of 16m. They incorporate single RD-170 engines, each with four chambers and a vacuum thrust of 806 tonnes per engine. The throttleable engines ignite about 13 seconds before lift-off to build up to full thrust, and consume 350 tonnes of kerosene and liquid oxygen. Their dry weight is 42 tonnes. Non-recoverable engines The booster engines burn for about 145 seconds, separate in pairs, and fall to Earth. They are not recovered, although there are plans to do so using parachutes, retro- rockets, or a combination of both, says Titov. Recovery is not certain, however, because the Soviets admit that the "expenditure on recovery depends to a considerable extent on the anticipated frequency of launches". The present boosters, nevertheless, include pods at the top and bottom which simulate hous ings for recovery systems. Clark says that Energia 1 had a lift-off weight of about 2,000 tonnes with boosters not fully laden, unlike the core stage. With full boosters, Energia weighs 2,400 tonnes, and can place 140 tonnes into LEO. Energia 1 carried a 24m-long, 4m-diameter single- engined piggyback stage which may have been unique to this launch or a standard configuration. Owing to a human program ming error before launch, the stage was aligned incorrectly for the firing and the payload was lost. The stage and whatever payload it carried (if at all) weighed about 100 tonnes. This stage will be replaced by other payloads, such as Buran. Energia will be uprated, the Soviets say, by the addition of two strap-on boosters, increasing total vehicle thrust to 4,900 tonnes, enabling it to place 180 tonnes into LEO. The payload will 22 FLIGHT INTERNATIONAL, 18 February 1989
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