Chapter CXXXVI: Dreams of a Dark Blue Sky - Part I
Chapter CXXXVI: Dreams of a Dark Blue Sky - Part I.
The 1937/38 Naval Estimates should have been a relatively pleasant experience for the Admiralty, for the first time in years the political and economic conditions were favourable for a serious expansion of the Fleet. The Navy had a politically well connected First Sea Lord, a re-armament friendly chancellor and there was a strong majority in the Cabinet and both Houses of Parliament for continued ship building. It was therefore somewhat unfortunate that such large disagreements broke out within the Admiralty about what exactly should go into the new estimate. While the fight was notionally around the design of the aircraft carriers, that was just the culmination of the broader debate around air power. This debate could be characterised as exercise vs experience, defence vs attack, board vs fleet or, to make it personal, Henderson vs Fisher.
By the start of the 1930s the Admiralty felt it had a solid understanding of carrier warfare, exercises with the existing carriers had shown that, for simple carrier vs carrier battles, the ship which got the first strike off would win. They had also shown that maintaining a constant fighter patrol large enough to completely fight off an aerial attack was impractical and that even with a dangerously distant picket you would never get enough warning to launch fighters to intercept incoming high altitude bombers. Carrier tactics had developed in light of this; an emphasis on scouting and long range operations, night strikes as a standard part of doctrine to help get the first strike in and the decision to keep the carriers within the main fleet to maximise the number of escorts and so volume of supporting anti-aircraft fire. The Ark Royal class of carriers was based on the outcome of this thinking; more aircraft allowed more scouting and more chance of getting a full size strike off first, thus aircraft capacity should be maximised. The tonnage limits in the naval treaties, and making sure the ships could fit into existing docks, meant the design had to be broadly the same dimensions and tonnage as the preceding Courageous class, but advances in technology (not least modern machinery and the substantial use of welding), and being a dedicated design rather than a conversion, gave them capacity to work with. The naval architects used this tonnage to boost the AA weapon fit and dramatically increase aircraft capacity, the Ark Royal class being notionally capable of carrying and supporting almost twice as many aircraft as her predecessors. The general feeling in the Admiralty was that future designs would follow this pattern, refining the concept rather than reinventing it.
The remote controlled target ship HMS Centurion during a live fire exercise. During her time as a target ship Centurion was regularly shot at by the fleet, shot at by coastal defence guns and, relevant for our purposes, bombed by the Royal Air Force. The 1929 exercises were particularly influential in shaping the thinking of the Admirals and Air Marshalls. Attacking from a medium altitude (5,000ft) the bombers managed an 18% hit rate against a slowly moving target that held a straight course and wasn't shooting back, the pilots had also been allowed multiple runs before finally dropping their practice bombs. While the Air Staff ignored these issues and declared the trials proved the bomber could do any role asked of it, in this case coastal defence, the Admiralty considered the results as validating their own relative lack of concern about high level bombing attacks.
This view was being challenged just a few years later by the influential figure of Admiral Reginald Henderson, the Third Sea Lord and Controller of the Navy. A former captain of HMS Furious he was subsequently appointed the first Rear-Admiral commanding Aircraft Carriers, making him one of the most 'air minded' figures at the Admiralty. As Third Sea Lord he was responsible for procurement and design, leaving him well placed to champion his views on carrier design and fleet composition. It is something of an irony that a man so keen on naval air power would end up pushing for the next generation of carriers to carry fewer aircraft than even the Courageous class, but there was method to this seeming madness. Henderson agreed with much of the carrier doctrine that had been developed, the difference was his view of where the fleet could expect to fight. In short he expected the Royal Navy to do most of it's fighting well within range of hostile land-based aircraft, whether it was the North Sea, Central Mediterranean or even advancing up the South China Sea to relieve Hong Kong and threaten Taiwan. There were exceptions, for instance the trade protection squadrons could expect to be deployed deep into the Atlantic and Indian oceans, covering convoys and hunting raiders, but the main battle squadrons would not. This presented an issue, for Henderson firmly believed that land based air would be both superior to carrier aircraft and more numerous. The superiority was not just a function of the poor deal the Fleet Air Arm got from the Air Ministry, though that doubtless played a part, but was a matter of physics. Given similar performance engines a naval aircraft would always be heavier than it's land based rival, due to the added weight from folding wings, naval radios and being stressed for catapult launch/arrestor wire landings, so would be slower. Moreover the preference was to use the reliable and durable (but lower powered for the same size) radial engines for FAA designs, putting them at a power disadvantage as well. On the matter of numbers we have already seen in Chapter LXXVII that the defence plans for Singapore called for 400 operational aircraft to be deployed, not counting the additional airframes available as attrition reserves; merely to match that force would require 6 Ark Royal sized carriers. Henderson believed it would be foolish to assume future enemies would not have similar, or larger, air forces deployed at their own key ports and fortresses.
There were a number of possible solutions to this, tactically the Royal Navy could have decided to deploy their carriers separately from the fleet in individual squadrons. This would make them harder to find and, once located, only the single carrier in that squadron was in danger not the entire fleet. In a world where the fighters on a carrier could not be expected to respond to a raid, being more about mopping up after an attack and shooting down spotters, scouts and fleet shadowers, this made a degree of sense. This was in fact the approach adopted by the United States Navy, any carrier not assigned to support the battlefleet would be dispersed into it's own separate carrier task force, which would operate independently from both the main fleet and any other carrier task forces. Henderson rejected this approach as it did not solve the problem, merely mitigated it, instead he determined the best solution was to tackle the core of the issue; the vulnerability of the aircraft carrier. Like the rest of the Admiralty, and indeed his US and Japanese counterparts, Henderson was relaxed about level bombers, he also shared the common Admiralty belief that bulkheads and bulges could provide a degree of protection against torpedoes, so it was the dive bomber threat that concerned him. Thus was born the concept of the armoured box carrier, as the name suggests the basic idea was to include a large amount of armour on the design to protect it against enemy attack. While sometimes referred to as an armoured flight deck, the concept only put the heavy 3" thick armour over the hangar and magazines (which was approximately 2/3rds of the flight deck length), the rest of the flight deck received 'only' 1.5" thick armour. It's also of note that it was an armoured box and the sides of the box would receive 4.5" thick armour plate, sufficient to provide protection against 6" shells at reasonable ranges and destroyer calibre weapons at all ranges. Henderson and his designers believed this would allow carriers to move outside the battlefleet screen (when turning into the wind to launch or recover aircraft for instance) without the risk of being vulnerable to ambush by enemy cruisers or destroyers.
A prototype Aichi D3A dive bomber undergoing diving trials in early 1938, after some major re-design and a new much more powerful engine was installed the D3A would eventually become the main diver bomber of the Imperial Japanese Navy. One of the more controversial aspects of the armoured carrier design was the thickness of the armour, the 3" thick plate was designed to resist a 500lb SAP (Semi-Armour Piercing) bomb dropped from any reasonable altitude. The controversy comes from the choice of a 500lb bomb as the reference weapon, because it was not the FAA or the Admiralty that picked it but the RAF. The specific advice given in 1934 was that Royal Navy would not have to face an enemy with carrier launched dive bombers carrying greater than 500lb bombs within the next decade. Arguably this was almost correct, lack of a high powered engine would limit the D3A to using 250kg/550lb bombs and it's successor would not enter squadron service with the IJN till 1943. But in reality the Germans would field a Stuka capable of hauling a 1,000lb bomb by 1938, the USN would order the 1,000lb capable SBC-4 variant of the Curtiss Helldiver the same year and even the FAA would get a 1,000lb capable dive bomber in service before the end of the decade.
The armoured carrier concept was certainly revolutionary but it was not universally acclaimed within the fleet, as Henderson would be the first to admit it came with several drawbacks. The most obvious was the reduction to a single hangar deck, halving the hangar area and so air group size, with a proportional reduction in aviation fuel, magazine and aircraft maintenance areas. The hull itself also had to changed and would be shorter and beamier than Ark Royal, as the design would have the same boilers and turbines as her predecessors the naval architects warned this less efficient configuration would cost 1 to 2 knots of top speed and reduce range. On the air group Henderson believed that 36 aircraft capacity would be sufficient for most missions, particularly as he was one of the strongest proponents of multi-role aircraft. With FAA squadrons being nominally 12 strong there would be capacity for three squadrons, these were pencilled in as two TSR squadrons (Torpedo-Spotter-Reconnaissance, this would become the Swordfish) and one fighter-dive bomber squadron (the original Skua spec was issued at the same time the armoured carrier concept was being developed). This was a smaller air wing than Courageous or Glorious but, by stripping out the dedicated reconnaissance and fighter aircraft and replacing them with multi-role designs, the effective striking power was tripled. In recognition of the importance of winning the reconnaissance battle and striking first, every aircraft on the armoured carrier would also be capable of scouting in some capacity. An additional bonus of the proposed air group was that the carrier would only be operating two types, which would simplify maintenance and operations and, it was hoped, offset the reduce stores and support areas. Taking all those points together Henderson felt confident that even though the air group would be smaller, it would be considerably more effective. As regards speed the design should still hit 30knots, which would be sufficient to more than outpace most of the battleline and so allow the carrier to conduct air operations and then 'catch up' with the fleet. It should also be noted that despite concentrating so much weight of armour up high, the loss of the hangar depth reduced the metacentric height considerably, meaning the armoured carrier would be more stable and have a tighter turning radius than Ark Royal.
The three 'Outrageous'-class carriers, HMS Courageous, HMS Glorious and HMS Furious, in the Grand Harbour Valletta during the 1934 Combined Fleet exercises in the Mediterranean. While the fleet clashes of 'Red' (the Royal Navy) vs 'Atlantis' (the un-named enemy) had shaped views on the effectiveness, or otherwise, of fighters it was the strikes at the end of the exercise that had been more divisive. The 'Red' force had had carried out a co-ordinated strike with aircraft from all three fleet carriers simultaneously attacking against the 'enemy' battlefleet. While demonstrating the concept of multi-carrier operations and massed strikes the results were disappointing, ironically due to a lack of 'mass' in the strike. With only one torpedo squadron per carrier, the rest being fighters or dedicated reconnaissance aircraft, barely 30 aircraft had been launched in the 'mass' strike, this had allowed the defending fleet to concentrate it's AA firepower and not be overwhelmed trying to deal with multiple threats. All involved agreed that the fleet needed a way to generate larger strikes in future, however they disagreed fundamentally on the best way to achieve this.
Overall the entire concept was solid enough, provided you believed the initial assumptions and were prepared to prioritise defence against land-based air over striking power and fighter cover. Henderson had the air experience to convince his fellow Sea Lords, the bureaucratic skills to push his design through the Admiralty system and the rank to over-rule everyone else in London. Had it not been for the Abyssinian War it is likely that his armoured box carrier design would have been ordered instead of Ark Royal's half-sister HMS Bulwark. But the war did intervene and events moved quickly, certainly far faster than the Admiralty's administrators; the ship building committee still had not finished planning it's 'Emergency' wartime shipbuilding programme when the war ended, a fact the Admiralty did it's best to keep quiet about. As peace returned Henderson discovered that the new First Sea Lord, Baron Keyes, was not as easy to bulldoze as his predecessor had been and insisted that the officers who had fought the Abyssinian War be consulted on the design. This was unfortunate for Henderson as it pulled the former Commander-in-Chief Mediterranean Fleet, Admiral Sir William Fisher, into the debate.
Admiral Fisher (no relation to the former First Sea Lord 'Jackie' Fisher) was the only figure who could challenges Henderson's claims of pre-eminence in carrier experience; the majority of the Fleet's pre-war exercises had been carried out by the Mediterranean Fleet under Fisher's command, as had the many wartime strikes carried out by the Fleet Air Arm during the Abyssinian War. Since that conclusion of that conflict and the signing of the Valletta Treaty he had been assigned to Commander-in-Chief Portsmouth, an assignment that would take on a surprising degree of relevance in the ongoing debate. While Fisher agreed with the problem, his proposed solution was wildly different and informed as much by ethos and doctrine as technology. Like much of his generation Fisher had been determined to learn the lessons of the Great War, one of which had been the importance of initiative and taking the fight to the enemy, not waiting to be told to attack. This was something the Royal Navy's officer corps had once instinctively understood, but which the late Victorian Admiralty had smothered with protocol, it had taken some nasty shocks during the Great War to show the folly of suppressing initiative. It is therefore unsurprising that Fisher instinctively took a dim view of carriers being designed on the basis of a passive strategy, this perhaps explains his very different reaction to the pre-Abyssinian War exercises. Where Henderson had seen ineffective fighters and 'the bomber always getting through', Fisher had seen compromised multi-role aircraft achieving significant, if incomplete, success and needing time, training but above all dedicated aircraft. The crash programme to get the Sea Gladiator into service for the Abyssinian war can be in large part credited to the efforts of Fisher and his indefatigable then deputy Vice-Admiral Forbes, both of whom successfully argued 'proper' fighters were desperately required.
A Hawker Hart starting a dive during the 1935 dive bombing trials. Arguably it was the Royal Naval Air Service that carried out the first dive bombing attacks during their raids on German Zeppelin hangars in the Great War. Their successors in the Fleet Air Arm remained supporters of the concept, but while the FAA's Nimrods (the naval version on the Hart) regularly practiced vertical dive bombing, the Nimrods were limited to a tiny load of 4 x 20lb bombs. Unfortunately the RAF was not as keen and so, while trials would continue throughout the 1920s and 30s and tactics were developed and refined, the Air Staff consistently refused to specify a dedicated dive bomber or supply one to the FAA. Officially this was due to concern that the very high casualties the tactic incurred (over 30% losses on a single mission in some cases during the Great War) were not worth the results. Unofficially strategy and physics played a role, the Air Staff remained convinced strategic bombers were the war winning weapons and it was very hard to produce an effective level bomber that could manage a steep dive, as the Germans would repeatedly discover to their considerable cost throughout the 1930s and 40s.
The Abyssinian War had not conclusively proven the issue one way or the other, the lack of any Italian carriers, dive bombers or even aircraft capable of carrying a torpedo meant the Fleet had not faced any real aerial threat. As a result much of the 'evidence' either way was still derived from war games and exercises which, as we have seen, were far from decisive and could support varied conclusions. Fisher however had a trump card, as C-in-C Portsmouth he was responsible for the Royal Navy Signal School and so was well aware of the work that department was undertaking. A fuller account of the Royal Navy's work on RDF (Radio Direction Finding) and it's co-operation, and competition, with their air force and civilian colleagues can be found in a later chapter, for now it is sufficient to say that Fisher was convinced of the potential of RDF to allow enough warning to make fighter interception a realistic and effective defence. This is hardly surprising, Fisher had spent the latter part of the Great War heading up the Admiralty's Anti-Submarine Division working on ASDIC (amongst other things) and tactics for hunting submarines. It was therefore natural for him to argue that, just as ASDIC had 'tamed' the underwater menace so RDF would do the same for aerial threats. This was not an argument that stood up to rigorous scrutiny, if nothing else the Abyssinian War had left much of the Admiralty unsure if ASDIC worked quite as well as they had thought, but it appealed to those in the Admiralty who prized action and initiative, terms that very well described the First Sea Lord Baron Keyes. Fisher conceded it could take a few years for the experimental radar sets to be fit to go to sea and fighter interception tactics fully worked up, but he pointed out it would also take at least three years to build and fit out the new carriers, so by the time they had finished the technology would be ready for operations. The obvious counter-argument was what if the technology didn't live up to the initial promise or wasn't ready on time? This would leave the fleet with 'vulnerable' carriers, whereas with the armoured box design the Admiralty could be 'sure' the resulting ships would have a degree of protection.
The compromise solution, which was soon suggested, was 'do both'; design a carrier with the capacity of Ark Royal but with an armoured box. With the Naval Treaties gone there was no reason to artificially limit the size of a carrier to 23,000 tonnes, so this appeared to offer a way out of the impasse. There were however serious issues with this approach, starting with the implications for the design. As has been pointed out Ark Royal was already near the limit of stability, adding a great deal of heavy armour up high would make that worse unless measures were taken. Unable to significantly deepen the draught, not if the carrier wanted to fit through the Suez canal and into most harbours, the only option was to substantially increase the beam. As most of the Empire's dry docks were width limited this would severely limit where the future carriers could be maintained and repaired, unless a programme of upgrades and extensions was carried out. The Admiralty was sympathetic to this problem, the limitations of the dry dock fleet being well known and had been identified as a potential issue for the next generation of battleships as well, the work would be expensive. While work to upgrade the docks around Rosyth and Tyneside had been sneaked into the 1936 Estimates, using money siphoned off from the Special Areas Act fund, the key south coast docks of Devonport, Plymouth and Chatham had not been eligible as those areas had not been hit as hard by the depression, while the overseas docks were another problem entirely. The problems with the compromise solution did not stop there, being substantially larger the ships would be more expensive, cost was not directly proportionate to aircraft capacity but it was linked, initial predictions were around £6 million a ship, 50% more than the armoured box design and twice that of Ark Royal. As the Sea Lords were quick to point out the current political good will did not extend as far as a blank cheque and the Fleet could not expect to get all eight new fleet carriers if they cost that much. The procurement division added their woes by pointing out that given the heavy demands on armour plate from the King George V and Swiftsure construction programmes, and the limited armour production capacity that had been mothballed during the Depression, some tough choices would have to be made on priorities if a large amount of armour was required for the carrier programme as well. Almost as an after-thought there was a severe bottleneck around capital ship machinery, quite aside from the boilermakers strike there was a shortage of turbine manufacturing capacity and as a larger carrier would require more power for the same speed, this would also be an issue. The deadlock was finally broken when the Fleet's other carrier requirements was brought up; trade protection.
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Notes:
I was merrily working along on this and suddenly realised I had hit 5,500 words and not actually finished the chapter. So I backed up a bit and decided this would be a two parter, hence the slightly cliff-hangar ending. That said I doubt it will be much of a cliff-hangar as I suspect people will guess what is coming next in general terms, though I hope I can keep it interesting despite that. It is such a beast as there is quite a lot to fit into British carrier thinking, but overall I think I've done the topic justice under the circumstances.
OTL Illustrious class ended up a bit smaller (only 33 aircraft) but the plan was 36. FAA doctrine was OTL, go after the carriers at all costs to knock out the enemies scouting and spotting capability. The grand strategy was that as the fleets closed on each other the carriers on both sides would clash and you wanted to win that fight (it would give you a recon and spotting advantage later) but it was just a prelude to the decisive fight between the battlelines. USN, IJN and RN all agreed on this at the time and, given the capability of early/mid 1930s aircraft and the lack of radar, it was a perfectly rational doctrine. It just didn't age well.
Early 1930s RN carrier groups were very much 'one type for one job' - 1 squadron Nimrod/Osprey fighter, 1 squadron Ripon/Baffin torpedo bomber, 1 squadron Fairey III recon. Maybe a couple of half squadrons of extras f they were avaiable, but as has been mentioned the FAA was always short of aircraft and pilots so that was normally just for major fleet exercises (and typically involved stripping Hermes/Eagle/Argus of any aircraft). Exercises are of course OTL, the RN would have liked to do more multi-carrier strikes but never got the change or really had the aircraft strength till late in the war. As has been mentioned the perpetual shortage of aircraft was a driver for multi-role aircraft even before the armoured carriers, but it became vital once the Admiralty committed to the OTL Illustrious-class.
Admiral Fisher is a real person, described one of the outstanding Admirals of his generation (and as "The tall Agrippa", because it's the Royal Navy in the Med in the 1930s, so Latin/Roman examples are basically compulsory). He was being lined up to be First Sea Lord after Chatfield had he not died in 1937 in an accident, which has obviously not happened here. He did indeed serve on the anti-sub committee in WW1 and did huge work on tactics, training, night fighting and naval aviation while he was Mediterranean Fleet C-in-C. As Butterfly Redux slowly catches up he will start replacing Cunningham in the Abyssinian War chapters, because Cunningham was just too junior at that point. His reaction to the exercises and championing of fighters is OTL, though it wasn't until Admiral Forbes (who was Fisher's deputy in the Med) became C-in-C Home Fleet that the Sea Gladiator came into service and worked started on a 'proper' fighter. I say proper fighter but it was the Fulmar, which while unfairly maligned, was still not a full-fat, no multi-role, single seater fighter. He did end up C-in-C Portsmouth in 1937 for a good few months before the accident and was involved in the RDF work ongoing at the signal school there, more of which later.
Bottlenecks are real, both on armour and turbines. OTL there was the Admiralty version of the Air Ministries 'Ring', the companies the Navy would keep in business to maintain capacity. The problem was the Treasury limited the funds available to match the planned building programme, so with everything notionally based on rearming by 1942 the capacity was sized accordingly. When it came time to accelerate there was no slack, particularly when the army started snaffling around trying to steal armour plate for it's tanks. Partial solution came from importing a few thousand tonnes from the Czechs, but as we shall see that is not an option in Butterfly so the Admiralty will just have to wait till the new capacity comes on-line and cut their cloth accordingly until then.
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