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.
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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 î 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:
• Four small solid rocket motors for initial axial acceleration before main engine ignition;
• 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;
• 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.
References
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
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Spaceflight, Vol. 40, January 1998
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