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Sputnik Series SL-1, SL-2 - 8K71PS

Soyuz-UOn 30 January 1956 the Government issued a decree to put into orbit in 1957-1958. "Object" D "" - a satellite with scientific equipment. 200-300 kg of scientific equipment was to be developed by the USSR Academy of Sciences. On January 14, 1957 the Council of Ministers of the USSR approved the flight test program R-7. And Korolev sent a memorandum to the Council of Ministers, writing that 2 missiles could be ready, in satellite version, in April-June 1957, "and launched immediately after the first successful launches of the intercontinental missile." In February, construction work was on the testing range, and two missiles were already ready.

Korolev, realizing that the equipment for the satellite would be done for a long time, sent an unexpected proposal to the government: " There are reports that in connection with the International Geophysical Year, the US intends in 1958 to launch an artificial satellite. We run the risk of losing priority. I propose instead of a complex laboratory - the object "D" to bring into space a simple satellite."

Sputnik Series SL-1, SL-2 - Western View

With the announced weight of Sputnik 1 at under 84 kilograms, it is understandable why Western observers in that period postulated the use of a much smaller launch vehicle than the real one. When people rushed out of doors to see the passing of the first satellites, usually they were really viewing that 28 meter rocket casing, like a Pullman railway sleeper tumbling end over end, rather than the spherical Sputnik 1, 0.58 meters in diameter, or even Sputnik 3 which was 3.76 meters long. Sputnik 2 remained attached to its rocket.

Some time later, when the United States launched the Project Score satellite in the same mode as Sputnik 2—namely, leaving the payload attached to the spent rocket casing—it injected the entire sustainer portion of the Atlas launch vehicle into orbit. The United States announced achievement of the world's heaviest satellite to date (3,969 kilograms). The useful payload was actually about 68 kilograms. This provoked Leonid Sedov of the Soviet Union into some testiness, when he pointed out that the total weight in orbit in connection with each of the three Sputnik launches had been in excess of the U.S. weight. The residual Soviet weight has been assumed to be about 6 metric tons, and the Sputnik 2 vehicle which like Score remained attached to the rocket body weighed 508 kilograms for a total combined weight of perhaps 6,508 kilograms.

Some time in the early 1950's a large Soviet rocket engine was developed for use in connection with the first ICBM, and it may have been considered even at the outset for space work as well. The Russians designated this, the RD-107. The engine burns kerosene and liquid oxygen, uses a single shaft turbine assembly to pump the oxidizer and fuel to four combustion chambers with exit nozzles and to two steering rockets. There are auxiliary systems to pump a hydrogen peroxide gas generator and to run a liquid nitrogen to nitrogen gas pressure supply. The engine operates at 60 atmospheres to produce a vacuum thrust of about 102 metric tons with an Isp. of 314 seconds.

A variant of the same engine is called the RD-108, differing from its predecessor primarily in having four steering rockets instead of two, and its vacuum total thrust is 96 metric tons. The first ICBM which also became the launcher for Sputnik 1 was assembled by placing four long tapered tanks of roughly cylindrical shape around a sustainer core. Each of these strap-ons had an RD-107 engine and the central unit had an RD-108. All five units with their 20 main nozzles and 12 steering rockets are ignited on the pad, and as soon as thrust builds up to lift off the pad, the rocket rises. When the boost task is over, the four strap-ons fall away leaving the sustainer core to continue burning for a time.

The total assemblage created a fairly graceful impression. The central sustainer core, 28 meters long, described from the ground up starts as a regular cylinder, then flares outward, and tapers back again, creating a hammer head effect. This peculiar shape was selected to blend with the four strap-ons which are modified elongated tapered cones. When all five units are strapped together, the result is a fluted pyramid effect with a maximum base diameter of 10.3 meters, including the four stubby fins.

This is the vehicle which the Russians claim first flew as their original ICBM from Tyuratam on August 3, 1957. Then it was used for the launch of Sputnik 1 on October 4, 1957, and likewise for the next two Sputniks. During that period the rocket had no upper stage, so it was not used very efficiently for payload weight purposes. The entire sustainer core was placed in orbit on these occasions, and one of the blurred Western photographs taken of such a rocket tumbling in orbit definitely suggests its hammerhead shape which has since been revealed by the Russians. Judged by the weight of the last and heaviest of these payloads, the lifting capacity of the rocket was about 2 metric tons to low circular orbit. It is possible that the residual weight of the spent rocket casing was on the order of 6 metric tons.

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Page last modified: 05-06-2018 18:57:49 ZULU