Sea Dart (missile) - Design

Design

Sea Dart is a two-stage, 4.4-metre (14 ft) long missile weighing 550 kilograms (1,200 lb). It is launched using a drop-off Chow solid-fuelled booster that accelerates it to the supersonic speed necessary for the operation of the cruise motor, a Rolls-Royce kerosene-fuelled Odin ramjet. This gives a cruise speed of over Mach 2.5, and unlike many rocket-powered designs the cruise engine burns for the entire flight, giving excellent terminal manoeuvrability at extreme range. It is capable of engaging targets out to at least 30 nautical miles (35 mi; 56 km) over a wide range of altitudes. It has a secondary capability against small surface vessels, tested against a Brave-class fast patrol boat, although in surface mode the warhead safety arming unit does not arm and thus damage inflicted is restricted to the physical impact of the half-ton missile body and the unspent proportion of the 46 litres (10 imp gal; 12 US gal) of kerosene fuel.

Guidance is by proportional navigation and a semi-active radar homing system using the nose intake cone and four aerials around the intake as an interferometer aerial, with targets being identified by a Type 1022 surveillance radar (originally radar Type 965) and illuminated by one of a pair of radar Type 909. This allows two targets to be engaged simultaneously in initial versions, with later variants (see below) able to engage more. Firing is from a twin-arm trainable launcher that is loaded automatically from below decks. The original launcher seen on the Bristol was significantly larger than that which appeared on the Type 42 and Invincible classes. Initial difficulties with launcher reliability have been resolved.