Soviet rocketry that Conquered Space
Part 4: The Development of a Four-Stage Launcher 1958-1960

By 1959, extensive theoretical studies on trajectories to Mars and Venus had shown the need to depart the Earth via a parking orbit. This meant building a three-stage vehicle capable of orbiting a fourth stage consisting of spacecraft and propulsion unit that was capable of putting the payload on an escape trajectory.


Early Planetary Plans

At the beginning of 1958 Korolyov planned launching a deep space probe to Venus in June 1959. The probe was to be put on an escape trajectory by the launch vehicles 8K73 or 8K72 as a back-up option (details of which appeared in Part 2, Spaceflight, February 1996, p.49).
Preliminary studies showed that this launch vehicle could send a payload of about 400-500 kg at the very best to Venus.
In the summer of 1958, OKB-1's project department started development of the first interplanetary spacecraft [3] for a launch to Venus (Object V1) in June 1959 and to Mars (Object M1) in September 1960.
But difficulties with Glushko's RD-109 engine for the third stage of the 8K73 launcher, the Moon shot failures of the 8K72 launcher and the delay of Object V1 development led to the abandonment of the Venus shot of 1959 and the postponement of the launching of Venus probes to January 1961. Moreover in 1959 it became obvious that the 8K73 project would not get converted to hardware at all.
As a new third stage for the R-7-based launcher, Korolyov suggested using the second stage of his new missile R-9.
Improved R-7 ICBM, the R-7 A

In 1958 OKB-1 started work on improved R-7 missiles designated R-7A and R-7M. The latter version received design/manufacture designation 8K710 and was to be capable of transporting a heavy warhead weighing some 5.37 tonnes to a distance of 12,000-14,000 km. To do this, however, it was necessary to increase the specific impulse of the 8D74/ 75 engines by 5-6 seconds more than that of the usual production ones. This turned out to be impossible at that time and so the R-7M was never flown. The former version, the R-7A was however developed as now discussed.

On 2 July 1958, the Soviet Government passed a resolution to develop a modified R-7 ICBM, called the R-7A, with an upgraded range of 12,000 km and a lighter warhead [1]. Moreover R&D tests and the first production 8K71 missiles had revealed a considerable potential for improvement of its systems including the control system.
The new version of ICBM received the development/manufacture designation 8K74 and used all-inertial guidance. A new control system enabled the warhead to achieve a high level of accuracy at the target without radio-correction. But the radio system remained as a back-up. During 1959, the engines 8D74 and 8D75 underwent the next improvements to put up their reliability. The modified motors of the 1959 version were equlnped with new vernier engines whici. had been developed by Glushko's OKB-456 instead of earlier ones that had been made in Korolyov's OKB-1. Automatic devices on the vernier chambers were simplified and reduced. The automatic devices on the 8D74's vernier nozzles were all dispensed with except at the oxidiser cut-off pyrotechnic valves. Due to a new design of the vernier motor's combustion chamber, the specific impulse increased. In order to increase the convenience of servicing during pre-launch preparations, some portions of the power-plant were moved within the aft compartment of the missile. So air-pressure reducers were transferred from the tu'rbopump's frame on the frame of the engine closer to the service hatch. A new ignition system carried out the firing of all chambers, both main and vernier ones, from a single timer.

Korolyov's New ICBM, the R-9

A new two-stage ICBM was conceived in 1957 and the original design for it, called the R-9, was prepared in 1958.
It would not be a rocket package as was the R-7, but a missile of classic tandem configuration with consecutive staging. The R-9's first stage (Block A in Russian terms) using LOX and kerosene would develop nearly 150 tonnes of lift-off thrust.
R-9 proceeded slowly at first due to serious problems with its engine units. In the end the R-9 project evolved into three programmes - R-9A (8K75) with the first stage powered by one of Glushko's four-chamber RD-111 engines, R-9V (8K76) with the first stage powered by a cluster of four Isayev's nitric acid-kerosene engines and R-9M (8K77) with the first stage powered by a cluster of four of Kuznetsov's one-chamber engines NK-9 [4]. (Note: later the Moon rocket N-1's third stage was powered by a cluster of modified NK-9 engines, the NK-9V!)
On 13 May 1959 after much debate the Soviet Government passed a resolution to develop the ICBM R-9A [5] and hence only the 8K75 was actualy built The first R-9A was launched о 9 April 1961 from Tyura-Tam*.
A novel feature about the R-9A was its second stage (Block B). It had ball-shaped oxidiser tanks and was conical in shape. (Note again: this concept was embodied later in the design of the stages of N-1!) The stage was powered by Kosberg's OKB-154 four-chamber engine 8D715 (the conventional designation of the motor is RD-0106) developing nearly 30 tonnes of thrust .
This second stage was planned to be the third stage of a new R-7A-based launch vehicle. The R-7A was an improved version of the R-7. See the box insert on the left.

First Interplanetary Launcher, 8K78

During 1958 and the first half of 1959, the Mathematical Institute of the Academy of Sciences or MIAN (its Russian acronym) for short, conducted extensive theoretical research on flight trajectories to Mars and Venus [7]. These studies resulted in the important conclusion that the launching of space carrier vehicles with unbroken powered flight directly on to an Earth- escape trajectory from Soviet Union territory leads to large gravity losses and decreases of payload weight Also such a launch puts extremely strict time-limits on the lift-off time, to within a matter of seconds during a whole launch day. The Soviets had to contend with these unfavourable factors during the first Moon shots of 1958- 1960 (see Part 2, Spaceflight, February 1996, p.49).
Then MIAN together with OKB-1 found another, much more efficient procedure for interplanetary launches: it was to put a payload together with the escape stage into a low Earth (parking) orbit then re-launch it on an interplanetary trajectory with the aid of the escape stage. That meant that it was necessary to build a three-stage launch vehicle which could put into low orbit a payload - the fourth (escape) stage with the spacecraft- of total weight up to 7 tonnes.
By early 1959 as soon as there were the first results of this study, projects of interplanetary versions of the 8K72/73 launchers and other variants were abandoned and Korolyov's OKB-1 immediately started work on the development of a four-stage launch vehicle, the 8K78, based on the ICBM 8K74 (R-7A). The new third stage (Block I in Russian terms) was hurriedly developed on the basis of the second stage of the ICBM 8K75 (R-9A) with more propellants and larger tanks. In order to retain the stage's aft compartment design, the lengthened oxidiser tank remained at the lower end of at Block I with a bail-shaped fuel tank positioned above it The Kosberg's OKB-154 had developed a space version of the 8D715 motor for Stage 8K78I with a longer burning time This version was designated 8D715K (the modem conventional designation is RD-0107) and in May 1960 two R&D test copies were delivered for assembly together with the Block I stage.

The Four-Stage Launcher

An important innovation was the fourth (escape) stage called Block L and its engine S1.5400. This motor developed by OKB-1 during 1959-1960 and fed with LOX and kerosene was designed, for the first time, operating over a closed-stage thermodynamic cycle! It was installed in gimbals for pitch and yaw control. For a roll control two vernier nozzles were placed on either side of the main chamber.
In order to ensure engine ignition after the unpowered coast in zero gravity, Block L was equipped with a special unit for initiating the firing, called BOZ (which in Russian stands for Blok Obespecheniya Zapuska or in English for Unit for Ensuring Ignition). The BOZ unit was vital for ensuring that Block L took up the correct position before ignition, so that when the propellants began to flow into the main chamber, re-start would occur in the correct direction. Portions of the BOZ unit were located on the truss structure connecting Block L with the third stage and consisted of:

  • Х Four small solid rocket motors for initial axial acceleration before main engine ignition;
  • Х Four big (145 kg) and two small (5 kg) spherical gas-storage bottles with nitrogen under high pressure for use in the attitude control system;
  • Х Gas thrusters, pneumatic vents and other devices of the attitude control and stabilisation systems;
  • . The instrument unit of the control system.
  • The BOZ unit was then jettisoned when the main engine of Block L stage had been fired. The stage Block L was equipped with an inertial control system that kept the third stage attached to the fourth stage during the coast after the second stage (core unit A) had separated. The basic R-7A was modified to raise the combined third-fourth stages to more than 30 tonnes weight and was designated 8K74/III. The operating pressure was increased in the tanks of both the strap-on boosters and of the central sustainer. Some portions of the missile's airframe were strengthened to cope with the larger weight above. A stronger open truss structure was mounted on top of the core unit A. The RD-107/108 engines were modernised and had the designations 8D74K and 8D75K respectively. The 8D74K reached full thrust through only one intermediate thrust stage not two as with its 8D74 predecessor. Both motors' turbopumps provided nitrogen consumption for increased pressurisation of the tanks by 10 per cent and 8 per cent respectively. In November 1959, the first basic R- 7A adapted for attachment to the new third stage was assembled at OKB-1's experimental plant in Podlipki and then integration tests were conducted with the prototype of the third stage and a dummy fourth stage. In December 1959, the prototype of the new launcher with the first three stages live and a dummy fourth stage was sent to Tyura-Tam Test Range for a suborbital test launch. The mock-up of the Block L (fourth) stage was inert but was equipped with a control system to keep Stages 3/4 on a trajectory up to dummy Block L separation. The prototype was successfully fired on 20 January 1960 and its payload with dummy escape stage splashed into the Pacific [8]. On 30 January 1960 the second test shot of the 8K74 with the additional third stage took place. By the summer of 1960 the R&D escape stage Block L was built and passed its first ground tests. These tests included a simulated engine firing and the real ignition of the turbopump in zero g conditions during flight of the aircraft-flying-laboratory Tupolev-104LL. It was the escape stage that produced most trouble during subsequent launches of the 8K78 carrier vehicle which will feature in a forthcoming instalment of this multi-part article.


  • 1. 'Rocket Troops of Strategic Destination', The Military-Historical Transaction, Moscow, 1992, p.47.
  • 2. From The History of Soviet Cosmonautics, Nauka (Science) Publishing Office, Moscow, 1983, p.242.
  • 3. M.V. Keldysh, Selected Works. Rocket Technology and Cosmonautics, Nauka, Moscow, 1988, p.260.
  • 4. S.P. Korolev Rocket Space Corporation ENERGIYA, 1946-1996, Moscow, 1996, pp.121-123.
  • 5. Space School, Newspaper of the International Space School, Leninsk, Kazakstan, No. 4, 1993, p.7.
  • 6. Russian Space History. Saie 6516, Sotheby's Auction Catalogue, NY, 1993, lot 29
  • 7. M.V. Keldysh, Selected Works, pp.243- 261.
  • 8. S. Gavrilov, 'Here is my heart for you..', Sovetskaya Rossiya (Soviet Russia) Publishing Office, Moscow, 1970, p.102.

  • * One of the launches of R-9A (on 17 October 1963) is mentioned by Academician Vasily P. Mishin in his diaries that were sold at Sotheby's auction on 11 December 1993. There the R-9A ICBM appears as "product No. 9" [6]. During 1958 and the first half of 1959, the Mathematical Institute of the

    на основе статьи Soviet Rocketry which conqured space из журнала Spaceflight, Vol. 40, January 1998
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