Armoured Carrier Hangar Design

The Illustrious class had been designed with a single hangar with the standard British 16 foot of clear height as was previously used in the Ark Royal. Most aircraft used by the Fleet Air Arm were well below this height and by 1938 the standard of measurement was the forthcoming Fairey Albacore torpedo bomber which was 13 foot tall. It was only the large amphibian aircraft such as the Supermarine Walrus and Sea Otter, carried to rescue the pilots of downed aircraft, that required the extra height. The two Implacable class ships had been intended to have either two 16 foot hangars or a lower 16 foot and upper 14 foot hangar (sources vary) however the extra height was sacrificed during the design process in order to maintain stability after extra side armour was added and both ships completed with 14 foot hangars. Indomitable had been laid down as a repeat Illustrious class but when supplies of armour plate from Czechoslovakia were delayed she was redesigned to incorporate some of the changes from the Implacable class, most notably the addition of an upper hangar of 14 foot height on top of the 16 foot lower hanger retained from her Illustrious half-sisters; the lower hangar was shortened to half length in order to incorporate additional accommodation space for the larger air group and was only served by one of the two aircraft lifts. Short sighted as the height policy may seem with hindsight, the designers were operating under the weight restrictions of the naval limitation treaties and losing the ability the carry amphibians was an acceptable sacrifice; future aircraft would almost certainly utilise backwards folding wings that wouldn’t require such tall hangars.

Fleet Air Arm Fighter Doctrine

Fighter doctrine in the Fleet Air Arm (FAA) differed to that of the U.S. or Japanese navies and there was a marked split between the need for a long range fighter for strike escort and short range defensive aircraft to screen the fleet. Escort aircraft needed additional fuel for long range and the difficulties of navigation over these distances meant that a second crew member was needed to serve as a navigator, as well as serving as an observer for the dual reconnaissance roles that these aircraft were also used for. Coupled with size limits and strict take-off and landing performance specifications, the perennially underpowered aircraft the FAA was lumped with suffered poor performance compared to their contemporaries. Defence fighters were able to have shorter range and a single pilot as they weren’t expected to venture far from the fleet and needed to match the performance of the attacking aircraft; unfortunately the type stagnated in the mid 1930’s - as high performance monoplanes became common the time available to intercept incoming strikes virtually disappeared and the main use of the type was believed to be the interception of aircraft shadowing the fleet. It was only with the introduction of air search radar and fighter direction methods at the start of the war that meant that interception became a legitimate option again. There were few options available to FAA in the category with the Ministry of Aircraft Production keeping a tight rein on high performance aircraft and engines for the use of the RAF and onerous restrictions on aircraft specifications for carrier use still being in force - the development problems of the Blackburn Firebrand and the failure at launch of the Sea Typhoon program did not help matters. As a result the Supermarine Spitfire, optimised for high speed at low altitudes and with a fantastic rate of climb, was the only viable option for the defensive fighter despite features such as the narrow weak undercarriage and poor view over the long engine that made it less suitable for carrier operations.

Lend-Lease Aircraft

The shambolic state of FAA aircraft procurement meant that they were an enthusiastic customer of American aircraft via Lend-Lease. Comparing the most up to date American fighters available from 1942, the Corsair and the Hellcat, specifications were very similar though the Corsair was slightly faster but the most notable difference was that the Hellcat was far easier and gentler to land on a moving carrier deck, not helped by the poor view over the Corsair’s lengthy engine installation, and as a result was much preferred by the U.S. Navy for at-sea service. This resulted in far more Corsairs being delivered to the British in 1943 and early-1944 as the U.S. Navy reserved Hellcat production for their own expanding fleet. The FAA was able to accommodate the difficult landing behaviour of the Corsair and it became an extremely formidable carrier fighter with one large proviso – its wings folded upwards rather than backwards. American carriers were designed with 17 foot 6 inches of hangar height and were able to accommodate this easily, but even after clipping the wings slightly the Corsair could only just squeeze into the 16 foot hangars of the Illustrious class and Indomitable’s lower hangar. Though large numbers of Hellcats were starting to be made available in late 1944, the British Pacific Fleet had already sailed with their existing aircraft; instead most of the Hellcats were reserved for the strike carriers – escort carriers tasked with supporting amphibious landings and strikes on secondary targets – where the types large bombload, high performance and sedate landing characteristics were prized. Large numbers of Hellcats were also used as night fighters or photo-reconnaissance aircraft rather than pure fighters.

The Pacific

The three Illustrious class carriers operated in the Pacific using Corsairs while Indomitable carried Hellcats and Indefatigable carried Seafires, though she had operated Hellcats prior to departing for the Pacific. Implacable, arriving very late in the war, also carried Seafires. While the limitation on Hellcat numbers was part of the reason Seafires were carried, there was another factor - by the time the British Pacific Fleet was operating off Okinawa the standard defensive air patrol was divided into 3 layers with Corsairs at high altitude, Hellcats or Corsairs at medium altitude and Seafires lower down. The Seafire had a fantastic rate of climb, double that of a Hellcat, and superb performance at lower altitudes which meant that despite the high accident rate they performed excellent service in the close range interceptor role and still had a place in the overall mix of fleet aircraft. The U.S. Navy did not initially have any aircraft of a similar type but there was one in development – the Grumman F8F Bearcat which also possessed an outstanding rate of climb, it arrived just too late to see combat during the war. Indomitable could have carried Corsairs in her lower hangar but it was only half length which would have restricted the number of aircraft to be carried and being served by only one elevator would have also been slower to launch large numbers of aircraft. Hellcats were therefore chosen as they could be housed in the upper hangar, a choice also determined by Indomitable’s status as the flagship of the carrier force – in the end her lower hangar was used as additional accommodation space for the fleet staff rather than for aircraft.

Sources:

British Carrier Aviation – Norman Friedman

The British Pacific Fleet – David Hobbs

British Aircraft Carriers - David Hobbs

The Fleet Air Arm Handbook – David Wragg

British Naval Aircraft Since 1912 – Owen Thetford