Molniya Launch Vehicle
4- The Added Stage Version for Eccentric Orbit and Escape Missions,A-2-e
Molniya Series SL-6
WITH PROBE ROCKET ADDED, A-2-e,
Overview, Supporting Facilities and Launch Vehicles of the
Soviet Space Program *1
1976-1980 Study
* Prepared by the late Charles S. Sheldon II and Geoffrey E. Perry M.B.E. Dr. Sheldon was the Senior Specialist in Space and Transportation Technology, Mr. Perry is a Senior Teacher at Kettering Boys School, England, and the leader of the Kettering Group of amateur satellite observers.
SL-6 Venera / Molniya
The A-2 version, just described, was itself a step back from the A-2-e, already partly described and shown in figure 11. In this version, there was indeed a seventh engine, in contrast to Voskhod and Soyuz. This added stage when used is contained within the shroud which covers the payload. The Russians after Luna 3 used consistently a special technique for their flights which required an extra stage. This was especially important for flights more nearly in the plane of the Equator, since the Soviet launch sites are at relatively northern
latitudes. The rocket assembly is launched from the cosmodrome to place the interplanetary larger stage plus the payload in low circular Earth orbit, where the burned out stage is separated. During the course of the first orbit as the payload heads northeast across the South Atlantic to cross Africa, a special orbital launch platform, never specifically described as to shape, dimensions, or weight, is oriented and from it the final payload is launched to higher speed by the escape rocket. This probe rocket, after it has done its work, is separated from the payload and flies on essentially the same path as the payload. It has not been described in detail in Soviet publications available in the West. However, it was shown diagrammatically in a Soviet pamphlet written in German, "Nachrichtenbruke in Kosmos" which described Molniya 1. This has subsequently been issued in English: "A Satellite's Overhead." The stage is shown as a stubby cylinder measuring about 2 meters in diameter and perhaps 2 meters long. Soviet payloads which are launched from the orbital launch platforms and given their impetus with this added escape stage also carry a special maneuvering engine for orbit adjustments and smaller verniers for orientation.
When this whole system works, it does a very effective job. The Soviet program is given added flexibility as to launch windows through the technique of orbital launch, and 'calculations can be made as to the final stage firing in the relative tranquility of the vacuum of space. This flexibility is important for the Russians who have lacked the worldwide network of land-based tracking and control stations which the United States has developed in cooperation with other nations. But the number of steps required to carry out a deep space mission, supported by automatic devices and a few ships, tended to expose these operations to a fairly high failure rate. Assuming that in general Soviet flight successes and failures are comparable to those of the United States because competent people in both countries are applying the same technology, then we see no particular reason why Soviet Earth orbital operations should be any less successful than those of the United States. But deep space work with the platform launch technique presents in fact another story. For example, the United States has made 65 launch attempts for escape missions, of which only 11, or 17 percent, have failed to escape. The Soviet Union has made an unpublished number of attempts to use the orbital launch technique, but we can note that of 68 Earth orbiting platforms carrying payloads intended for the Moon, Mars, or Venus, 20 failed to send their probe payloads beyond Earth orbit, or a failure rate of 29 percent, higher than the U.S. rate. The total failure rate is undoubtedly higher for deep space missions because additional flights presumably did not even attain Earth orbit. However, in the period 1976-80, both countries achieved complete success in the attempts to launch escape missions—six for the United States and three for the Soviet Union.
References:1. SOVIET SPACE PROGRAMS: 1976-80, SUPPORTING FACILITIES AND LAUNCH VEHICLES, POLITICAL GOALS AND PURPOSES, INTERNATIONAL COOPERATION IN SPACE, ADMINISTRATION, RESOURCE BURDEN, FUTURE OUTLOOK PREPARED AT THE REQUEST OF HON. BOB PACKWOOD, Chairman, COMMITTEE ON COMMERCE, SCIENCE, AND TRANSPORTATION, UNITED STATES SENATE, Part 1, Dec. 1982.
The Molniya-M launch vehicle
The Molniya-M launch vehicle essentially consists of a basic Soyuz launch vehicle with an additional third stage. Like the lower stages, this third stage is powered by liquid oxygen and kerosene via a 11 D33 main engine. Originally developed for lunar and planetary missions beginning in 1960, the Molniya-M is now used to place payloads of 1.6-1.8 metric tons into highly elliptical (~400 km by 40,000 km) Earth orbits inclined 63 degrees to the equator. The upper stage and the payloads (normally a Molnlya communications or Kosmos early warning satellite) are encased within the launch shroud and subsequently placed into a low altitude parking orbit by the lower stages. About half a revolution of the Earth later, the third stage is ignited for transfer into the elliptical orbit. During 1993-1994 eleven Molniya-M launch vehicles performed flawlessly, bringing the overall reliability to about 89% after nearly 300 missions. Molniya-M vehicles can be launched from either Baikonur or Plesetsk, but since 1990 the boosters have only operated from Plesetsk (Reference 254). For several years, a modification of the Molniya-M launch vehicle has been under consideration. The third stage would be replaced by a new Fregat stage which is derived from the main propulsion unit of the Phobos interplanetary spacecraft developed by the Lavochkin Scientific Production Association and launched in 1988. Tentatively designated Molnlya-A, this launch vehicle would be capable of placing 5.4 metric tons into a sun-synchronous orbit. Introduction of the Molniya-A could come as early as 1996 (References 255-258).
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