R-36-O / SL-X-? FOBS

In the early 1960s, the Soviets needed a way to overcome the forward base advantage held by the west. The west had forward bases in Turkey, Europe, and Asia from which shorter range missiles and bombers could attack the USSR. Following the failure of placing missiles to Cuba, the Soviets turned to technology to overcome the lack of forward positioning. The Vostok launches had previously demonstrated that the Soviets possessed the technology necessary to orbit a space vehicle and then land it in a specific target. In this, there was an implicit assumption that nuclear weapons could be placed in orbit and returned to Earth at any time and place. Khrushchev made this suggestion in 1961, but in March 1962, as part of the rhetoric preceding the Cuban crisis, he made yet another, more ominous suggestion.

"We can launch missiles not only over the North Pole, but in the opposite direction, too. Global rockets can fly from the oceans or other directions where warning facilities cannot be installed. Given global missiles, the warning system in general has lost its importance. Global missiles cannot be spotted in time to prepare any measures against them."

This statement was the first hint of a new concept called the fractional orbit bombardment system (FOBS) that had been under development since 1961. System "partial-orbital bombardment" [hastihno-orbitalinoi bombardirovki] (in the western sources was called Fractional Orbital Bombardment System, abbreviated FOBS) was developed in the CB "Southern" (Chief Designer - M.K.Yangel ) in the mid 1960s. The main purpose of the system - a missile strike on the United States with the least expected directions. It replaced the global rocket GR (8K713), developed in OKB-1 (Chief Designer - S.P.Korolev).

The Global Rocket 1 (GR-1) requirement of 1961 called for a system to place a large nuclear warhead equipped with a deorbit rocket stage into a low earth orbit of 150 km altitude. Creation of the missiles and orbiting module was tasked OKB-586 (now CB "Yuzhnoye"; Chief Designer Yangel), rocket engines - OKB-456 (now NPO "Energomash"; Chief Designer V.P.Glushko) system Management - SRI-692 (now CB "Khartron"; Chief Designer V. Sergeev) Control devices - SRI-944 (now NIIKP; Chief Designer V. Kuznetsov). Battle launch complex was developed in KB-SM led by Chief Designer EG Rudyak. For preliminary design, and in 1963, technical documentation and manufacturing of advanced missile designs, the development began was completed in December 1962.

The composition of the missile system and missile design is largely similar to the base R-36 - a two-stage missile with tandem steps. Equipped with a liquid rocket engine, is used as fuel UDMH + AT. The missile is stored in the filled form, ampulized. Silos (mines) and command post (CP) are protected from the damaging factors of nuclear explosion. The launch was gas-dynamic, with the launch of a rocket propulsion system in silos The main difference from the basic rocket is to use an orbital head (MSA) with a brake motor unit (TDU), a control system, the combat unit (WB) with a charge capacity of 2.3 Mt and a system of electronic protection MSA. The control system, orientation and stabilization MSA - an autonomous inertial. It is supplemented by a radio altimeter, which controls the height of the orbit twice - at the beginning of the orbital portion and before applying the brake pulse. Brake stage designed to provide MSA descent from orbit. It is equipped with its own propulsion system, automatic stabilization and control a range of automatic, instructs the shutdown TDU.

Modifications to the steps I and II ballistic missile 8K67 when used as part of the orbital rocket is reduced mainly as follows:

• instead of a single instrument compartment orbital rocket mounted instrument compartment with reduced dimensions and an adapter, which house equipment SU. After removing the calculated orbit instrument compartment disposed therein SU equipment is separated from the body and at the MSA performs orbital flight to the launch of the MSA 8D612 engine brake control module
• in the tail section of the II stage of the rocket is not installed containers with decoys and Tx system of protection against missile defense
• changed the composition and arrangement of the SU devices additionally installed radio altimeter ( "Chestnut" system). According to the results of flight tests of rocket design has been finalized
• all connections filling-drain line power rocket motors are made welded, with the exception of four compounds ampuliziruyuschih membrane plugs installed at a gas-discharge line
• Connection gas generators supercharging oxidizer I and II stages with tanks tanks made welding
• filling-drain valves installed in the enclosures of tail sections I and II stages; • revoked fuel drain valve stage II
• flanges for releasable connection of the membrane units at the entrance to TNA main and steering engines replaced with welded pipes or flanges for welding to the conduitsd
• in field welding of stainless steel components with elements of the aluminum alloy cans firmly applied bi-tight adapter manufactured by stamping from a bimetal sheet

The weapon’s 1,700 kg orbital stage was designated the 8F021 OGCh, which comprised a fuselage, an instrument section with an inertial guidance system, the de-orbit engine section, and an 8F673 ~5 Megaton nuclear warhead. The 8F021 would, as it neared the de-orbit manoeuvre entry point, start the AT/UDMH liquid fuelled de-orbit engine turbopump using a solid propellant gas generator. Exhaust gasses from the turbine were used for vehicle attitude control, using a 4+4 thruster arrangement. This de-orbit engine design later formed the basis of the Tsiklon 3 ELV S5.23/RD-861 third stage orbital engine, rated at 78.710 kN / 17,695 lbf. The cited CEP for the RV was 1.1 km.

Flight tests were completed on May 20, 1968. Adopted Resolution of the Government of the USSR on November 19, 1968. The first and only regiment with orbital missile 8K69 atonement for combat duty Aug. 25, 1969. on the NIIP-5. In the regiment was deployed 18 launchers.

The orbital missile 8K69 was initially deployed on 19 November 1968, and the first regiment with the R-36 orbital missiles was put on alert on 25 August 1969. The missile was phased out in January 1983 in compliance with the SALT-2 treaty, which prohibited the deployment of FOBS systems.

The R-36O SS-9 variant 3 SCARP with a modified upper stage was equipped with an orbital nose cone, which contained an instrumentation section, a single-chambered liquid propellant retrorocket motor and a nuclear warhead. Western estimates were that the orbital missile carried a one- to three-megaton warhead. Once placed into low-Earth orbit, the ICBM possessed unlimited range and the ability to approach the US from any direction, avoiding US northern-looking detection radars. This type of approach would give little or no warning that a warhead was inbound. The reentry vehicle came down in less than one revolution, hence the "fractional" orbit.

Following the failure of their first two tests in 1966, the Soviets conducted nine launches between 25 January and 28 October 1967 following the same distinct flight profile. The missiles would be launched in the late afternoon into an elliptical, near-polar low-Earth orbit and de-orbiting over the Soviet landmass before one complete orbit. This profile allowed the Soviets to monitor the deorbit, reentry, and impact. US planners viewed FOBS as a pathfinder system intended to precede a conventional ICBM attack and take out key retaliatory forces. The FOBS would circumvent the existing US ballistic missile early warning radars and hit SAC airfields and missile silos before the bombers could take off or missiles launched. FOBS could have also conceivably destroyed ABM radars, disrupt US retaliatory capability, destroy command posts, the White House, and the command and control network. But, due to its limited accuracy and payload, FOBS was deemed ineffective against hardened targets.

The 1967 Outer Space Treaty basically allowed the Soviets to orbit everything but a nuclear warhead. The FOBS system allowed them the ability to deploy the weapons system minus the warheads without violating the treaty.

By 1968 the Soviets' FOBS program conducted two flights per year to indicate operational status. Although the Soviets deployed FOBS in 18 silos, political events in the U.S. prevented any serious examination of the system. At that time it was unclear to US intelligence whether the Soviets were developing FOBS, or ballistic missiles with depressed trajectories and deboost capabilities. The orbital rocket 8K69 was decommissioned in January 1983 in connection with the Treaty on Strategic Arms Limitation Talks (SALT-2), which had agreed a ban on such systems. Based on the provisions of the Treaty of 12 of the 18 constructed in the area of the cosmodrome Baikonur rocket launchers eliminated, and the remaining 6 were converted to test upgraded ballistic missiles. Later on, the missile 8K69 was created by a family of launch vehicles "Cyclone".