8A92 Operations

The first 8A92 launch vehicle took off on 1 June 1962 carrying reconnaissance satellite Zenit-2 No.3, but just 1.8s after blast off the engine 8D74 (RD-107) of the strap-on booster Block B suddenly cut off [1]. Due to abnormal loads, the booster B broke away and fell to the pad damaging it. The central sustainer Block A carrying the upper stage went out of control with the remaining three boosters attached, fell back to Earth about 300 m from the-pad and blew up [1]. The launch pad was under repair for almost two months. The next launch came on 28 July 1962 and was successful, as also were the following seven launches. But the launch attempt on 10 July 1963 ended in serious failure again. Two seconds before lift-off, the hydrogen peroxide valve of the strap-on booster Block V suddenly cut out. As a result a turbopump stopped and the engine 8D74 of the booster V shut down. Nevertheless the launcher, with the engine units of three boosters and the central sustainer operating, blasted off. The faulty booster V broke off at once and the launcher exploded. On this occasion the launch pad was extensively damaged. Preliminary studies of these failures showed that it looked as if some sort of fault had knocked out the power supply circuit of the engine's automatic devices. The next launches were delayed until the cause had been revealed. Investigations and tests took more than three months and led to the conclusion that a remote commutator that switched power to the booster's control system was the cause of these failures [2].
This unit was intended, in particular, to switch off the power supply just before separation of the strap-on boosters at T+120s. But due to a violent dynamic shock, which could have been produced by either engine ignition or change to a higher thrust level or at blast off this commutator sometimes acted spontaneously and left the engine's automatic devices unpowered [2]. On the suggestion of N.A. Pilyugin, Chief Designer of the control system, the commutation circuit was changed. Subsequently no strap-on boosters broke off [2]. Following successful launches on 18 October and 19 December 1963 the first Soviet space reconnaissance system Zenit-2 based on the satellite 11F61 and the launcher 8A92 was put into operational service with the Soviet Military Forces in March 1964 by order No. 0045 of the Department of Defence of the USSR [3].
On 17 March 1966, the launch vehicle 8A92 lifted off for the first time from Plesetsk and revealed to Western analysts the existence of this Soviet launch site. On 28 August 1964 a prototype of the first experimental meteorological satellite of the Meteor class was placed in orbit by the launch vehicle 8A92. In total 50 launches of the 8A92 took place, five of which ended in failure and two were partly successful. (See the Table for brief comments on the 8A92 launches.) The final launch of the 8A92 vehicle came on 12 May 1967. Then the launcher was taken out of service. Subsequent Zenit-2 satellites were orbited by launch vehicle 11A57 (which will be described in Part 10). Meteor satellites were launched by a modified version of the 8A92, designated 8A92M.

8A92M - An Improved Version of the 8A92.

During 1961-1963, responsibility for all improvements, the development of new versions, flight tests and operation of R-7 based launch vehicles was placed with the Kuibyshev Branch of OKB-1 (now TsSKB-Progress, Samara) headed by D.I. Kozlov [4,5]
In 1965 the decision was taken by the Branch leadership to end the manufacture of the 8A92 [6] since at that time a new three-stage R-7 based launch vehicle 11A57 was in service. But it turned out that a launcher of the 8A92-class was the most suitable vehicle for putting Meteor satellites into near-polar orbits due to its ascent profile and the burning time of the Block E (Stage 3) [6]. During 1966 the Kuibyshev Branch of the OKB-1 developed a modified version of the 8A92, designated 8A92M, especially for placing satellites in polar Sun-synchronous and near-polar orbits. The basic packet of Stages 1/2 of the 8A92M remained basically unchanged although on-board control and telemetry cabling was lightened and the telemetry system itself was replaced by an improved one. Stage 3 (Block E) was equipped with a new telemetry system and a new light compact inertial control system designed with more precise units. The new nose fairing was unified with the same unit which was being used a top the 11A57 launcher, i.e. it was lengthened by 0.4 m. The first 8A92M launch was on 28 February 1967 from the Plesetsk launch site and it put into orbit a satellite of the Meteor class officially announced as Kosmos-144. Up to 1984 all Meteor-1 and 2 satellites (excluding the Meteor-2 launched by the 11K68 Tsiklon-3 launcher on 25 March 1982) were launched by the 8A92M. On 18 December 1969 launch vehicle 8A92M placed in orbit a satellite of the ELINT-class, Tselina-D, named officially as Kosmos-389. This spacecraft, intended for detailed electronic intelligence, was developed by M.K. Yangel's Design Bureau Yuzhnoye (Dnepropetrovsk) during 1965-1969. The 8A92M launcher again turned out to be the most suitable vehicle for placing these satellites in orbit. This launcher had been putting ELINT satellites into orbit for fourteen years when, during 1981-1983, it was replaced by the launch vehicle 11K68 (Tsiklon-3). The 8A92M also placed in orbit the Russian Meteor-Priroda (Resurs-O) and Indian IRS-1 Earth resource satellites. It achieved high reliability. In total, 90 launches took place and only two of them ended in failure (on 8 January and 1 February 1969). One launch attempt was aborted on 15 October 1970 when the launcher did not leave the launch pad. One launch attempt ended in tragedy.

Disaster and Aftermath

On 18 March 1980, the launch vehicle 8A92M had being preparing for routine launch at pad No.4 of the Ptesetsk cosmodrome with the ELINT satellite Tselina-D atop. At 19:01 Moscow Time, during fuelling operations, the launcher blew up. As a result 51 men were killed and a few dozen were injured [7]. Immediately after the disaster, a State Commission was established to investigate the cause of the tragedy. For two months the commission examined a number of versions of the event and came to conclusion that one member of launch team - a corporal - was the main culprit [7]. During fuelling he had discovered a LOX leak at a junction of a filling pipeline and the LOX inlet of Stage 3 and he was trying to eliminate the defect by wrapping the site of the leak with a wet rag[8.]. In me opinion of the commission it led to the explosion of Stage 3 and the launcher as a whole.
But there was another conclusion based on much better grounds which was rejected from the official statement of the commission. The cause was more likely to have been in a hydrogen peroxide filter of the ground fuelling pipeline. This filter was soldered using a wrong solder, not tin but tin-lead. It is known that lead is a good catalyst for chemical decomposition of hydrogen peroxide. Contact of flowing hydrogen peroxide with the solder-catalyst caused the peroxide to vigorously decompose, resulting in overheating and melting of the solder, particles of which got into the hydrogen peroxide tank of the launcher where the same chemical reaction started [9]. The tank blew up causing a fire in the aft compartment of the rocket units which led to the explosion of the whole launch vehicle. Of course, these investigations, as also the fact of the disaster itself, were kept under a curtain of secrecy for many years by Soviet propaganda. After this incident all R-7A based launch vehicles (at that time three versions were in operational service, - the 8A92M, 8K78M and 11A511U) underwent the same modifications. Some improvements were made to the aft compartments of Stages 1/2, ground fuelling equipment and the rules of pre-launch servicing to increase fire and explosion safety. Cables, multiple plugs, pipelines in the aft compartments were wrapped in foil and some parts were made from fire-proof materials. An additional system for putting out a fire was added. The fire-explosion-proof versions of launch vehicles based on the R-7A have received additional letters, PVB, in their designations, i.e. their complete designators became 8A92M-PVB, 8K78M-PVB and 11A511U-PVB. PVB in Russian stands for Pozharo-Vzryvo-Bezopasnaya or in English for Fire-Explosion-Proof. The last launch of the 8A92M-PVB vehicle took place on 29 August 1991. The launcher put the Indian satellite IRS-1 B into orbit. This shot became the first and the last commercial launch of the Soviet Union. December saw the end of the USSR as a result of the August Putsch of 1991. Now the officials of the Russian Military Space Forces have conferred the names Vostok-2 and Vostok-2M on the launch vehicles 8A92 and 8A92M/92M-PVB respectively.

Reference

Correctione

In Part 7 of this series of articles {Space-Flight, 40, No. 9, September 1998), the LOX-UDMH engine designation in the first column on p.362, line 20 should read 80711 and not 8D710.