May 1933
The Defence Requirements Committee report laid out the problems with the FAA and the Carriers in blunt language.
First, the two other powers operating carriers both had 2 large, capable ships modified from WW1 battlecruisers. Of the experimental carriers the Royal Navy operated, only 2, Courageous and Glorious, were considered anything more than experimental (the Furious was considered useful in limited circumstances), and both Japan and the USA had plans to build new, purpose built carriers in their next annual building programs, which would leave the RN even more at a disadvantage. The aims of Germany and Italy were unclear, and in the case of Germany they had of course no sizeable navy, but future threats needed to be considered.
The conclusion was simple; at least one new design carrier, the building of which had been proposed - and put back - since 1925, must be set in motion as soon as possible. The shipbuilding capacity was more than adequate, indeed the construction of such a ship would help alleviate the terrible unemployment in the North of England. A carrier, it was pointed out, was considerably cheaper than a battleship, and not subject to supply bottlenecks like its main guns.
Second, if a new carrier (and ideally more than one carrier) was to be built, it would need suitable planes. It was clear from looking at the ongoing designs for the RAF that a new generation of carrier planes would be needed. Granted, that would be expensive, but their development would take 4 years to maturity, so a specification should be offered to the usual aircraft manufacturers for some suitable designs.
Getting additional funds for aircraft development and carriers would not of course be easy, but it was pointed out that the threat in the Far East was only getting greater with each year, and the aims of Germany were looking worrying in the long term. Also, we had ample tonnage available under the London treaty, so it would hardly be warmongering to build a carrier or two to replace the old and obsolete conversions.
Discussions with the treasury took time, but the Admiralty was quite adamant about their needs (neglecting to mention that they also wanted to get the carriers underway before they needed more money for new battleships). In the end they didn't get all they wanted. One carrier was approved for the 1934 program, and new fighter, dive bomber and TBD models were authorised for development. To reduce costs, engines and all other equipment (where possible) was to be either existing or commonly developed by the RAF. The Admiralty had hoped for two, to at least match the Americans, but one was better than nothing.
There had been considerable argument over exactly what the new carrier would look like, and in the hope of getting approval the Admiralty had, after many, many meetings, decided on a design. It didnt please everyone, but at least no-one hated it enough to resign
Since the displacement under the treaty was 27,000t, the DNC had been told to look at a number of proposals in the 25,000t range, to allow some additions if necessary and to keep the displacement to a level that the government would be pressing for in teh next naval armament talks. The big arguments had been over the armour scheme and the hanger size and arrangements. There had been the idea of copying the Americans with an open hangar, but in the end it was decided that the advantages of a closed hanger, with its ease of protection against gas, easy blackout and warmth in winter conditions outweighed a few more aircraft and a cooler condition in the tropics.
The armour had caused a lot more argument, added to which was the fact that armour production was currently quite limited, and while expansion of the plant was being arranged, there wasnt an infinite amount of armour to play with, It was first of all agreed that deck armour of some sort was necessary; the carrier would certainly be used in the North Sea and Mediteranean, where land based air would be found, and the carrier needed to survive direct attack. This was considered less likely in the Pacific, where the distances involved meant only naval air was likely to be encountered, but it wouldnt hurt to have it. In the end it came down to 3 main choices
A heavily armoured deck to keep out 500lb bombs
An unarmoured deck, with a protected hangar deck
A flight deck thick enough to initiate a bomb, plus a protected hangar deck.
It was pointed out that while on paper the flight deck armour looked good, it would involve a lot of weight high up, and probably limit the hangar height from the 16' currently under consideration for the new planes.
In the end it was decided to compromise and go for the initiating flight deck and a fully armoured hanger deck to protect the magazines and machinery spaces. To reduce the weight, the side armour was reduced to 2" from the 4.5" necessary to defeat heavy shells, as it was felt that the whole point of a carrier was NOT to get close to enemy heavy ships in the first place! However protection sufficient to stop splinter damage and aircraft cannon fire was considered essential. A flight deck just over an inch thick would be laid down - this would also handle the planes currently being designed, as well as future planes which would certainly be heavier, and a 4 1/2" thick hanger deck protecting the machinery and the magazines. Since this effective 'wrote off' the hanger in the case of bombing, it was decided to fit a horizontal armour plate (with opening door to transfer aircraft if necessary) so that a single bomb hit would only take out 1/2 of any aircraft stored below. Since the structure above the hanger deck was (relatively) light, it was expected this would make repairs in case of a successful attack take less time.
DNC reported that on 25,000t with the suggested armour scheme he could provide space for about 45 aircraft in a single hanger, depending on the type. This was looked on unfavourably, particularly compared to foreign carriers current or building, and in fact Courageous already carried 48 (admittedly slightly smaller) planes. DNC offered to carry another 20 aircraft as a deck park, but the feeling was that while a deck park was fine in the Pacific, it made less sense in the North Atlantic in winter, as well as leaving more aircraft out in the open and vulnerable to attack. Again a compromise was reached with what was called the 1 1/2 hanger carrier - a full length upper hanger, 16' high, and a half length lower hanger, again 16' high. This would carry 64 aircraft, comparing much more closely to foreign designs, and the rest of the space at the lower level would allow the necessary crew quarters and to allow some maintenance to be undertaken on long deployments. And if for some reason it became necessary to carry more aircraft, the deck park was still an option.
To reach the necessary speed of over 30kt, it was felt a 4-shaft ship was necessary, on about 148,000hp.While trunking for 4 shafts was heavier than for 3, the arrangement was actually a bit simpler, as the design displacement and hangar size allowed more flexibility in the disposition of the necessary trunking.
The TDS would have a depth of about 15' given the hull width necessary to carry the weight of the armour, slightly more than had been originally intended, but this also allowed more oil to be carried inside it.
Finally the ship would carry 8x2 4.7" guns for high altitude defence, and 6x8 2 pdr pompoms for close defence. It had originally been hoped that the 5.1" gun would prove suitable, but it had been found that the shell was simply too heavy (in fact the 4.7" gun proposed wasnt developed, and the ship completed with 8 twin 4.5" AA guns) While conversations with the Americans had consolidated the internal opinions that the air group was the most efficient defence, no defences were perfect and defence in depth would give far more security. Hence the heavy AA and the armour, in view of the need to operate in the Med and the eastern parts of the North Sea. While these arrangements in fact reduced the size of the air group, it was felt that overall it gave the best chance of the carrier surviving air attack. There were concerns and discussions about surface attack, but it was pointed out that even in the worst case of surface attack during bad weather, the carrier could run away from anything big enough to damage it (and in the bad weather, even destroyers were unlikely to be able to catch it)
The design displacement was 24,800t (although the complete ship would actually come in at over 25,000t)
The Ark Royal would be laid down on 1st June 1934 for commissioning in July of 1937.