Armoured Flight Deck - Doctrine and Design

Doctrine and Design

The Royal Navy had to be ready to fight a war in the confines of the North Sea and Mediterranean Sea, under the umbrella of land-based enemy air forces. The Royal Navy, with its extensive network of bases and colonies in the Pacific ocean, had also to be ready to fight in the vast expanses of the Pacific, as did the USN and the IJN, but the USN and IJN did not have to worry about operating in the Mediterranean. The differences in construction were determined by doctrine that was largely driven by the different approaches to the same tactical problem: How to destroy the enemy's aircraft carriers while surviving the inevitable counter strike. Prior to WWII the RN and USN both recognised that the dive bomber could disable the flight decks of enemy aircraft carriers:

...From about 1933 on, the Admiralty showed increasing interest in dive-bombing, as the best means of accurate delivery against small and highly manoeuvrable ships. Dive-bombing was also particularly attractive as a means of neutralizing enemy aircraft carriers, which some in the Fleet Air Arm considered their primary targets. British observers seem to have been impressed by US demonstrations... —

The RN was thus faced with designing a carrier that would be survivable under the conditions to be expected in the Atlantic, Mediterranean, and Pacific Oceans, and before the development of effective naval Radar; these conflicting demands resulted in the development of aircraft carriers whose decks were armoured against 500 lb Armour Piercing bombs and 1000 lb General Purpose bombs. The RN considered that an unarmoured carrier would be unlikely to be able fly off more than one deck load of strike aircraft prior to being attacked so the armoured flight deck carriers accepted a reduction in hangar capacity to the equivalent to one deck load of aircraft. USN, IJN some RN Fleet carriers such as Ark Royal had sufficient aircraft capacity to allow for two ranges, each equal to a full deck load of strike aircraft. The RN and IJN limited their aircraft carrier's aircraft capacity to the capacity of their hangars, and struck down all aircraft between operations. The USN, typically, used a permanent deck park to augment the capacity of their aircraft carrier's hangars. The use of a permanent deck park appeared to give USN carriers a much larger aircraft capacity than contemporary RN armoured flight deck carriers. The flight deck armour also reduced the length of the flight deck, reducing the maximum aircraft capacity of the armoured flight deck carrier, however the largest part of the disparity between RN and USN carriers in aircraft capacity was due to the use of a permanent deck park on USN carriers.

The Royal Navy also had the disadvantage that they entered into WWII with the Royal Navy being pitted against large, land based, air-forces whose aircraft also had superior performance to all existing naval aircraft, while the RAF's increased demand for high performance land based aircraft, after the Fall of France, actually retarded the production and development of Fleet Air Arm aircraft. On the other hand, the RN rapidly introduced new technologies, such as radar which enhanced the defensive capability of aircraft carriers. The RN thus had to develop new operational doctrines during the war. The USN, in contrast, was able to benefit from technology transfers from the UK and the wartime experiences of the RN, which was freely shared with the USN, prior to its entry into the war, allowing it to anticipate the changes needed to prepare its carriers for the coming conflict with Japan. The USN designed the armoured flight decks of the Midway class carriers based upon an analysis of the effectiveness of RN armoured flight decks. The IJN also benefited from being able to observe the effectiveness of RN aircraft carriers in action, while both the USN and IJN were able to introduce new aircraft types, prior to their entry into WWII.