Missile R-29 Vysota (SS-N-8 Sawfly)

The R-29 was the first Soviet sea-based ballistic missile with intercontinental range. Preliminary design work began in 1963 under a competitive programme that set a naval adaptation of a land-based missile, for the D-8 system, against a purpose-built compact two-stage naval missile for the D-9 system. A Defence Council session in 1964 selected the purpose-built design, and a Council of Ministers decree authorising development followed on 22 September 1964. The requirement was a threefold increase in range and a 1.5-fold increase in throw-weight over the preceding Soviet submarine-launched missile.

The R-29 is a two-stage liquid-propellant missile carrying a single separating re-entry vehicle. The all-welded body uses waffle-pattern AMg-6 aluminium-magnesium panels with integral tanks and no intertank or transition compartments; both propulsion units sit inside the propellant tanks in a "submerged" layout, and the conical, spherically blunted re-entry vehicle is carried inside the second-stage fuel tank, inverted relative to the flight direction. The 4D75 first-stage and 4D76 second-stage engines each combine a single-chamber sustainer with two single-chamber steering engines burning nitrogen tetroxide and unsymmetrical dimethylhydrazine, ampulised at the factory. Guidance is astro-inertial: the R-29 was the first Soviet ballistic missile to use azimuthal stellar correction of the flight plane and the first to carry an onboard digital computer. Russian sources give a CEP of about 1,500 m for the baseline missile, Western estimates about 900 m. It carried a 1 Mt warhead, Western sources assessing yield in the 0.6–1.5 Mt band, together with ballistic missile defence penetration aids — folded decoys matched to the radar cross-section of the re-entry vehicle, stowed in cylindrical containers in the second-stage tank and ejected at warhead separation. Launch is possible submerged or surfaced, including from the pier or after surfacing through ice, at boat speeds up to 5 knots, from depths down to 50 m and in sea states up to 6.

Testing ran from submersible-stand launches of full-scale mock-ups in the Black Sea, through 20 ground-stand launches at Nenoksa between March 1969 and November 1971 — one of which destroyed the launcher when a sustainer exploded in the tube — to submarine trials from the converted Project 701 boat K-145 beginning on 25 December 1971 and subsequently from K-118 and K-279, two of which ended in missile explosions and prolonged repairs. The D-9 system was accepted into service on 12 March 1974 and equipped eighteen Project 667B submarines, known in the West as the Delta I class. Deleting the penetration aids yielded the longer-ranged R-29D, accepted with the D-9D system in March 1978 aboard nine Project 667B and four Project 667BD boats, the latter — the Delta II class — carrying sixteen tubes but firing in two salvos of twelve and four. The R-29DU, with a heavier and higher-yield re-entry vehicle, was accepted in June 1986.

The Soviet and Russian navies were the sole operators. Intercontinental range allowed patrols in the Barents, White, Kara, Norwegian, Okhotsk and Japan seas and under Arctic ice, inside protected bastions, without transiting Western SOSUS barriers. Across the D-9 family 368 launches were conducted, 322 of them judged successful. The R-29R and the R-29RM Shtil succeeded it; decommissioning of the carriers began in 1994 and ended with K-447 Kislovodsk on 5 March 2004.