Invincible Class Escort Cruiser
HMS Invincible, 1979
HMS Illustrious, 1989
The Escort Cruiser had been in development since the 1960s and many design studies had been made when the decision was made to postpone the construction until after the CVA carriers had been completed. The 1966 Study 22 was taken as the basis for future design work, the main change being the switch to an all-gas turbine powerplant. The Command Cruiser was not immediately justifiable and indeed by 1970 the Treasury were pushing for the cancellation. However, the need to maintain the Sea King fleet at sea (each Type 82 could carry two but not maintain fully for long deployments) and the need to strengthen the air-defences of the Carrier Group enabled the Navy to get approval for two Escort Cruisers (as the type was renamed due to its full weapons capability against air, surface and submarine targets. A third ship was wanted but with pressing manpower and economic constraints this was not possible. Both ships commissioned at the end of the 1970s and were given two major updates in the 1980s to modernise their defensive systems.
The class also had a secondary Commando Carrier role with some hangar space given over to vehicles and additional bunks for soliders and vehicle stowage on the flight deck.
HMS Invincible R05 June 1977
HMS Illustrious R06 November 1979
Length: 600ft (oa), 576m (wl)
Draught: 24ft 6in
18,500 tons standard
Four Rolls-Royce Olympus TM3B gas turbines totalling 97,000 hp and 8 Paxman Valenta diesel generators
Max speed: 30kts
Endurance 7,000nm at 18kts
2x1 20mm Orkileon (replaced by GAM-BOI mounts 1985-88)
(2x1 30mm DS-30 mounts, added 1985-88)
1x2 Sea Dart SAM (38 missiles), fire-control by two Type 909 (later upgraded to GWS-31 standard 1988-91)
1x Ikara launcher (24 Ikara ASW & Woomba SSM), fire-control by two tracker-directors
9x Westland Sea King HAS.2 helicopters (hangar capacity for 12) (later 9x Westland WG.34 HAS.1 Merlin) (in Commando role up to 9x Westland Sea King HU.4/Westland Wessex HU.5 and 4x Westland Scout AH.1, later 9x Westland Sea King HC.4/ Westland HC.2 Merlin and 3x Westland Lynx AH.6)
Radars & Sonars
One New Surveillance Radar 3-D, 1x Type 1030 STIR, two Type 1007 navigation, two Type 909 FCR, two Ikara directors, one Type 2016 active sonar, UAA-1 and UA-series ESM, type Type 670 'Heather' jammers (replaced by Milpost jammers in 1988-91), two Type 675 anti-targeting jammers, Type 982 torpedo decoys.