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Aviation History
1962
1962 - 0173.PDF
FLIGHT International, 1 February 1962 PIONEER ICB ALTHOUGH nearly every American is aware that the complete Atlas Weapon System WS-107A-1 is now an operational ICBM, we are equally aware that this did not happen overnight. We can pick up the thread of the long—oftern painful— story with the first test of a two-engine Series A missile which took place on June 11, 1957. Ten seconds after ignition, the hold-down pins withdrew and missile 4A lifted off the pad at the Cape. It climbed a few thousand feet. Then, after one engine failed, it went into a series of violent manoeuvres—including a complete loop— with the tanks still loaded with propellants. The range safety officer pushed the destruct botton, killing the first missile after less than a minute. Despite the apparent failure, several things had been proved, including the incredible structural integrity and the excellent engine gimballing—both things about which there had been considerable doubt on the outside. And, at least, the thing flew! On September 25, 1957, there was a repetition of the first shot, when missile 6A behaved the same way after engine shut-down. Although a lot can be learned from an apparently unsuccessful test, this was of little cheer when news of the first Sputnik flashed round the world on October 4, 1957, followed by the dog-carrying Sputnik 2 the following month. In December the first Vanguard geophysical year satellite rocket blew up on the pad. Emotions were high at the Cape on December 17, 1957, when Atlas 12A was counted-down on the pad. This missile did everything its designers had hoped for. Its two engines burned for the full two minutes, long enough to propel the vehicle 600 miles down the Atlantic Missile Range. The fourth Series-A bird worked as well as the third, but the next three were chalked up as "partial" successes." The eighth and last of the A-series—as you can see by consulting the score card—on page 178—was a success. Now the development phase really started, some 11 years after the Convair crew first began dreaming. The first of the B series, in which the feasibility of dropping the booster and separating the nosecone was to be tested, failed on July 19, 1958, before the booster separated. Again the concept hung in the balance until missile 4B was fired on August 2, 1958. This was one of the most significant flights in the whole story, since it marked the first time that the booster separated, the sus- tainer continued and the nosecone separated as planned after the retro-rockets fired. By the time the seventh B was fired the re-entry vehicle reached the specification range of 5,500 n.m. The eighth B was shot in a spectacular prestige stunt intended to show the world that, despite Soviet success in orbiting dogs and their implied success with long-range ballistic missiles, Uncle Sam was not far behind. Missile 10B, with a special low-drag nosecone, soared out of Cape Canaveral on December 18, 1958. Instead of tilting into the pre-ballistic trajectory after booster separation, the sustainer carried the complete tankage into orbit with an apogee of 911 miles (off West Australia) and a perigee of 110.6 miles. On the thirteenth pass around the world 10B relayed a tape-recorded Christmas message from President Eisenhower. This was named project Score, and it ended when 10B burned up in the atmosphere 33 days later. Series C Atlas was short-lived. It consisted of five launchings, two completely successful, the last in July 1959. By now the pressure was on to make the missile operational, and to freeze the design for production. The first of the operational D series was flown in May 1959, before the last of the Cs; it failed. Few major changes distinguished the B, C, and D series, although there were many modifications to some hundreds of the 40,000 airborne parts. The D introduced a glass-fibre booster housing, and other weight-saving modifications. Greatest of the sources of worry was the reliability of the many systems components, and little has changed in that respect even today. The many valves and switches which must operate precisely, in an environment which combines extremes of temperature, very high vibration across a broad frequency spectrum, and high sustained g loading, make life very difficult for the systems 175 ATLAS AND SPACE-AGE WORKHORSE In the first part of this article, published on January 18, the historical and political background to Atlas was surveyed, and the missile was described in detail. In this second, and concluding, instalment, an account is given of the flight trials programme, of operational deployment of the missile and of the role of Atlas as a space booster. By IAIN PIKE The first fight, on June II, 1957. During these unexpected man oeuvres the airframe was stressed far beyond its design limits, but it remained intact engineers. For example, the tank pressurization valves have caused many problems in controlling the proper pressure head over the propellants. There is a known instance of over-pressurization following booster separation, in which the tanks ruptured com pletely at high altitude. Atlas is only the flying part of a vast weapon system; for every dollar spent in the air two are spent on the ground. A huge amount of ground support equipment is required to load the missile with propellant, check out its systems and maintain it in a state of readiness. The problems associated with this equipment were staggering at the inception of the programme. Today the D series is earmarked as the space booster, and major changes have been introduced with the E and F models. In May 1960, 56-D went 9,040 statute miles with an operational Mk 3 re-entry vehicle plus 1,0001b of test instrumentation. Model E was the first to get the advanced Rocketdyne MA-3 engines, which required revision to the thrust structure of the airframe. Some Atlas Ds have been fitted with the all-inertial guidance system described earlier, which is standard on all E and F missiles. The presence of the inertial system is betrayed by the ungainly box
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