Thor Launching Rocket Almost Ten Years Old

Press, Volume CVI, Issue 31187, 11 October 1966, Page 22

Thor Launching Rocket Almost Ten Years Old

Next January will be the tenth anniversary of the first firing of a Thor rocket. In 10 years the Douglas Thor has won a reputation for versatility, reliability and sound design which gives it much in common with the Douglas DC3 aircraft. Both have earned the affection of all who work with them and they are both unequalled as workhorses. The Thor was born from a crash programme to give the United States an intermedi-ate-range ballistic missile (1.R.8.M.) in the mid-19505. The Thor flight tests started only 13 months after the development contract was awarded —a remarkably short time for such a project. The flight tests showed that much had to be learned because the first four launchings were failures. Thor 1 toppled back on its pad and burned. The second was destroyed by the range-safety officer when it strayed off course, and so on with vital lessons being learned each time until Thor 5 made the first successful flight on September 20, 1957, just two weeks before the world’s first satellite was launched.

Like a phoenix, the Thor rocket survived its early fiery setbacks and has emerged as a highly successful rocket. It has helped to launch more United States satellites than any other first stage booster and has had its performance ratings stretched far beyond its original capabilities. Its reliability is now first-class:

last January, for the second time in succession, the Thor rocket's perfect performance in its space shots earned the Douglas Company a half million dollar bonus. This followed a record of 51 consecutive successes at the Western Test Range in California during 1964 and 1965. By itself the Thor is in- ■ capable of hurling a payload, into orbit. It needs one or | more upper stages to give; the payload enough speed to stay in space. As early as its fourteenth launching the Thor was combined with two upper stages to become the Thor-Able and early the following year, 1959, the Thor was mated with the newly available Agena stage to become the Thor-Agena, which placed Discoverer I in the first orbit ever to pass over the North and South Pole. The Thor-Agena combination is still in use, as also are developments of the Thor Able: the Thor Able-Star and the famous Delta. Delta’s Debut Delta made its debut in 1960 when it placed Echo I in orbit. This followed an earlier failure caused by a malfunction in its second stage. The Thor first stage performed perfectly. After Echo I the Delta performed faultlessly for 23 consecutive firings—a record for a triple stage rocket. More than 40 Deltas have now been launched and they have brought into the headlines

spacecraft like Telstar, Syncom and Early Bird which are revolutionising the com munications industry: the Tiros and Essa weather satellites which can spot more hurricanes in a day than an army of observers could in months; and a host of other scientific satellites. All of these satellites are operating for the benefit of mankind: not a bad result from a rocket originally designed to deliver weapons of mass destruction.

i The future of the Thor rocket seems particularly bright. The Thor-Agena and the Delta will continue in service for many years to come because of their versatility and ability to launch the smaller class of satellite most economically. The versatility of the Delta is almost a byword in the space industry: it is the only rocket which has launched payloads into solar orbit as well as into synchronous earth orbits where the satellite seems to just hang in the sky, and it is the only launch vehicle to have hurled a satellite into a polar orbit from Cape Kennedy. This difficult task requires a complicated dog-leg trajectory which fakes the rocket lover Cuba and Panama before the payload is finally injected into its Polar orbit at a point west of Peru. This manoeuvre, which is enough to make the range safety officer's hair stand on end, has now been attempted four times with complete success. It is safe to say that there is no kind of earth orbit which

cannot be reached by a Delta launch vehicle, especially now that a Delta launch pad has come into service at the Western Test Range in California. Thor’s Performance Performance of the Thor continues to be improved. In 1963 the lift-off thrust of the Thor was almost doubled from 80 to 150 tons by strapping on three solid-fuel rockets, to create the thrust-augmented Thor. This technique was introduced to the Delta series with number 25, which launched Syncom 3. A few months ago the Thor itself underwent a considerable face-lift. The familiar cigar-shape of the Thor has disappeared in the new longtank Thor which was unveiled a few months ago. Its completely cylindrical shape is 14 feet longer than the old Thor and it can lift a 20 per cent heavier payload. A Delta rocket incorporating the longtank Thor will, with augmented thrust, be able to send into orbit three times the payload of the original 1960 Delta It is impossible to guess what the shape and performance of the Thor will be in another 10 years. Perhaps the nex ; t improvement will be an increase in the thrust of its Rocketdyne engine which has not been altered much in the last decade. On the other hand, if the Thor is retired by 1976, it is difficult to imagine the booster that will replace it. Probably the Thor will stay in service until some kina of airbreathing carrier vehicle rather like a supersonic transport aircraft is available to boost the upper stages to the fringes of space.