R-27 (ballistic missile)

The R-27, carrying the Soviet index 4K-10 and known in the West as the SS-N-6, is a submarine-launched ballistic missile with a single stage and storable liquid propellant. GlobalSecurity.org describes it as the first sea-based liquid-propellant missile in the world. Its designers welded the whole airframe, placed the rocket engines inside the fuel and oxidizer tanks to shorten the vehicle, and filled and sealed the tanks at the factory with long-storable propellants, so pre-launch work took about ten minutes and successive missiles could be fired about eight seconds apart from a flooded launch tube. Sixteen missiles were carried aboard each Yankee class nuclear submarine. Western assessments put the Mod 1 range at about 1,300 nautical miles and the Mod 2 at about 1,600, with a third mark carrying non-independently targetable reentry vehicles, and a radio-guided variant, the SS-NX-13, was also studied. The page notes that Russian sources do not report a two-warhead version of the Mod 3. The missile first appeared publicly in a Moscow parade in 1967.