Implacable-class aircraft carrier

Indefatigable underway, 7 November 1944
Class overview
Name:	Implacable class
Operators:	Royal Navy
Preceded by:	Illustrious class
Succeeded by:	Audacious class
Built:	1939–44
In service:	1944–55
Completed:	2
Scrapped:	2
General characteristics
Type:	Aircraft carrier
Displacement:	32,110 long tons (32,630 t) (deep load)
Length:	766 ft 6 in (233.6 m) (o/a) 730 ft (222.5 m) (waterline)
Beam:	95 ft 9 in (29.2 m)
Draught:	29 ft 4 in (8.9 m) (deep load)
Installed power:	148,000 shp (110,000 kW) 8 Admiralty 3-drum boilers
Propulsion:	4 shafts 4 geared steam turbines
Speed:	32.5 knots (60.2 km/h; 37.4 mph)
Range:	12,000 nmi (22,000 km; 14,000 mi) at 10 knots (19 km/h; 12 mph)
Complement:	2,300 (1945)
Sensors and processing systems:	1 × Type 277 height-finding radar 1 × Type 279 early-warning radar 1 × Type 281 early-warning radar 6 × Type 282 gunnery radars 4 × Type 285 gunnery radars
Armament:	8 × twin QF 4.5-inch dual-purpose guns 5 × octuple, 1 × quadruple QF 2-pdr anti-aircraft guns 18–21 × twin, 17–19 × single Oerlikon 20 mm anti-aircraft guns
Armour:	Waterline belt: 4.5 in (114 mm) Flight deck: 3 in (76 mm) Bulkheads: 2 in (51 mm) Hangar sides: 2 in (51 mm) Magazines: 3–4.5 in (76–114 mm)
Aircraft carried:	81
Aviation facilities:	1 catapult

The Implacable-class aircraft carrier was a class of two aircraft carriers built for the Royal Navy during World War II. Derived from the design of the Illustrious class, they were faster and carried more aircraft than the older ships. They were initially assigned to the Home Fleet when completed in 1944 and attacked targets in Norway as well as the German battleship Tirpitz. Subsequently, they were assigned to the British Pacific Fleet (BPF).

Indefatigable was the first ship to go to the Pacific and attacked Japanese-controlled oil refineries in Sumatra en route. She participated in Operation Iceberg, the invasion of Okinawa in March–April 1945. Implacable's arrival in the Pacific was delayed by a refit and she did not begin operations against the Japanese until June. The sister ships participated in the attacks on the Japanese Home Islands in July and August. Indefatigable was the only carrier chosen to continue operations after most of the BPF withdrew to prepare for further operations in early August. After the Japanese formal surrender in September, Implacable ferried Allied troops and prisoners of war back to Australia and Canada for the rest of the year.

The sisters returned home in 1946; Indefatigable was used for the rest of the year to transport troops before being placed in reserve in 1947 and Implacable became the training carrier for Home Fleet. Indefatigable was converted into a training ship and reactivated in 1950 for service with the Home Fleet. Implacable was relegated to the reserve that same year and modified into a training ship in 1952. The sisters were scheduled for modernisation during the mid-1950s, but it was cancelled as the modernisation of the carrier in the queue ahead of them proved to be too expensive and lengthy. The sisters were decommissioned in 1954 and sold for scrap in 1955–56.