The SA-N-6 Grumble (Russian designation S-300PMU Rif/Fort) is a Russian ship-launched anti-aircraft missile, a derivative of the land-based SA-10 Grumble. Like its land-based counterpart, the SA-N-6 is intended to take on a wide variety of targets, including fixed wing attack aircraft like the F/A-18 Hornet, helicopters like the SH-60 and missiles like the Harpoon or Tomahawk. Also, like the SA-10, it can engage ballistic missiles. However, unlike the land-based variant, it was not optimized for this role, since Russia did not believe that a sea-based ballistic missile defense was particularly useful. Instead, they gave it an anti-ship mode.
Since the naval version of the missile retains the extremely high velocity of the land-based version, arriving at over Mach 4 (faster than a 130mm artillery shell), and has a 143kg high-explosive fragmentation warhead (compare this to Exocet's 160kg!), it is exceedingly effective in the anti-ship role, capable of crippling a Type 42 destroyer in one strike, or seriously damaging a Nimitz-class nuclear aircraft carrier. Its main weaknesses in this role are its high flight profile, and semi-active radar homing, which requires the launching ship to have line of sight to its target. Later versions of SA-N-6, dubbed Favorit, have infrared terminal homing which eliminates the second weakness, and improves its effectiveness against low-RCS aircraft like the F-117 Nighthawk.
The Grumble is, however, a rather large missile. Consequently, it can only be carried by large warships. The Kirov class missile cruisers have 12 8-round vertical launchers, while the Slava class has eight octuple VLS. A single Kara class destroyer, the Azov, was built with eight Grumble VLS in lieu of her SA-N-3 Goblet systems, presumably as a test platform for the system. The newer Kirovs and the Slava class RFS Varyag carry the Favorit variant.
SA-N-6 has been replaced in development, but not in deployment, by the SA-NX-20 Gargoyle, a navalized version of the S-400 Triumf missile system. It is currently only deployed on the Kirov class cruiser Pyotr Velikhy.
Its primary competitors in the anti-air missile market are the American RIM-66 Standard and the joint French/British/Italian Aster 30. It is less maneuverable than either one, but makes up for this in typical Russian fashion with meanness - it has nearly twice the flat-out speed* and more than twice the warhead of Standard, which itself has nearly five times the warhead of Aster (62kg versus 13kg).
- Based on publicized figures for Standard. Some estimates suggest their top speeds my be fairly similar.