| P-70 Ametist (NATO reporting name: SS-N-7 'Starbright') | |
| Origin: | Soviet Union |
| Type: | Anti-ship missile |
| Is Missile: | yes |
| Service: | 1967-1992 |
| Used By: | Soviet Union, Russia, India, North Korea (unconfirmed) |
| Designer: | Vladimir Chelomey |
| Design Date: | 1958 - 1968 |
| Manufacturer: | NPO Mashinostroyeniye |
| Production Date: | 1966 - 1987 |
| Number: | 631 |
| Weight: | 3500kg (7,700lb) |
| Length: | 7abbr=onNaNabbr=on |
| Speed: | Mach 1.0 |
| Vehicle Range: | 65km (40miles) |
| Filling: | 4G66 HEAT Warhead or 200 kt nuclear |
| Filling Weight: | 1000kg (2,000lb) |
| Propellant: | Solid fuel |
| Depth: | 30m (100feet) |
| Boost: | 7 seconds (tube exit to main stage) |
| Guidance: | Inertial guidance, terminal active radar homing |
| Launch Platform: | Charlie-I & Papa class SSGNs |
The P-70 Ametist (NATO reporting name: SS-N-7 Starbright, GRAU designation 4K66; ru|П-70 «Аметист» 'Amethyst') was an anti-ship missile carried by Soviet and Indian Project 670 submarines, as well as the Soviet Project 661 Anchar. It was soon succeeded by the P-120 Malakhit (SS-N-9 'Siren').
Fielded on June 3 1968, it was the first missile system in the world to be launched from a submerged submarine. From 1968 to 1987, a total of 631 missiles were built.
The P-5 Pyatyorka (SS-N-3 Shaddock) missile required the Project 659 submarines carrying them to stay surfaced after firing to send mid-flight guidance updates. This made submarines very vulnerable to enemy attack, so in the 1960s the Soviets started working on a new missile that could be fired whilst submerged, and a submarine would carry it. These became the P-120 Malakhit and Project 670 submarine.
However, problems with the engines of the P-120 Malakhit forced the Soviets to design a sub-launched missile based on the P-15M Termit (SS-N-2C 'Styx') as a stopgap measure for the first batch of Charlie submarines. This became the P-20L, later renamed the P-70 Ametist.
The P-15M was fitted with an L band active radar homing sensor and a new radar altimeter both developed for the P-120, but there was no room for a datalink in the smaller P-15M. Folding wings were added to reduce the size of the missile, and the missile could be launched at a maximum depth of 30m (100feet).
The short range of the P-70 meant it could rely on inertial navigation and radar-homing, and as such did not need mid-course updates from a radar on the submarine. Consequently, along with the addition of the radar-altimeter (which allowed for a much lower cruise altitude than previous missiles), the novel sub-surface launch capability meant that reaction time for surface targets was minimal.
As a result, the ability to deploy in littoral and close-range combat scenarios without necessitating exposure of the launching submarine more than made up for its lack of range compared to the P-5.
The P-70 went into service with the Soviet Navy on the first Project 670, on June 3, 1968.[1] About 200 were produced.
India leased the "Chakra" Project 670 submarine from January 1988 to 1992, to gain experience of operating a nuclear submarine.