What it says in the tin basically. In OTL Britain laid down 10 Colossus class ships in 1942-43, followed by 6 larger Majestic class in 1943 and then the Centaur class in 1944, going from 18,000t to ~20,000 and then 26,000t full load in two years.
So how do you get the British designers to start with a larger ship, ideally Centaur sized straight from 1942 or from the time of the Majestics? I understand the light fleets were initially the response to needing more carriers for convoy protection, so if the battle of the Atlantic is going better for the allies does this suffice total the design process towards larger ships earlier for example?
To summarise what has already been written by other contributors.
No. The Colossus and Majestic classes weren't initially the response to needing more carriers for convoy protection. They were designed and built to work with the fleet. Which is why they were called light fleet carriers. If they'd been designed for convoy protection my guess is that they'd have been called heavy escort carriers.
The 10 Colossus class were designed to operate aircraft weighing up to 15,000lb. The 6 Majestic class were ordered as Colossus class but they were modified to operate 20,000lb aircraft whilst under construction. The Centaur class was designed to operate 30,000lb aircraft and that was the major reason for the increase in size and more powerful machinery.
So firstly the Admiralty has to introduce the 30,000lb aircraft limit early enough for the first 16 light fleet carriers to be built as Centaurs instead of Colossuses and Majestics. My guess is that it has to be at least two years earlier. I have no idea what would make them do that.
The next problem is to find the extra labour and steel needed to build the larger hull and the more powerful machinery. This probably means the cruisers Blake, Hawke, Lion and Tiger are suspended before they were laid down to provide said labour and steel . They'd be re-ordered as Neptune class cruisers in 1944 and cancelled at the end of the war. The material, money and labour used 1954-61 to complete Blake, Lion and Tiger can be used to do something else and there will be no temptation to convert them into interim escort cruisers because they won't exist.
If 16 Centaurs were laid down 1942-43 instead of the 10 Colossus and 6 Majestic class then its highly unlikely that Albion, Bulwark, Centaur and Hermes would be laid down 1944-45 and they'd be cancelled at the end of the war. It's also almost a dead cert that they would have been cancelled at the end of the war and broken up on the slips if they had been laid down. In both cases that's because 16 light fleet carriers capable of operating 30,000lb aircraft had already been completed or were at a more advanced stage of construction so the Admiralty would have decided that the best course of action would be to cancel them and use the limited financial and industrial resources that Austerity Britain could allocate to naval construction to do something else.
However, every cloud has a silver lining. This cloud has several.
One of them is that the four Centaurs laid down instead of Hercules, Leviathan, Majestic and Powerful would be completed by the end of 1948 instead of being suspended in May 1946. That means that instead of 12 light fleet carriers completed and 8 suspended or being built at a slow pace at the end of 1948 the navies operating British light fleet carriers have a total of 16 completed ships and none under construction. Plus all 16 completed ships are capable of operating 30,000lb aircraft which is a great improvement on the 10 ships capable of operating 15,000lb aircraft and 2 capable of operating 20,000lb aircraft that were available at that time in the
"real world".
If Albion, Bulwark, Centaur and Hermes were laid still laid down 1944-45 and then cancelled at the end of the war the resources put into the first three would be used to accelerate the completion of Ark Royal and Eagle which I estimate would be completed up to 2 years earlier in the case of Eagle and 4 years in the case of Ark Royal. The resources put into completing Hermes would instead be put into completing the original Eagle in 1959 to the same standard as Hermes in 1959, i.e. two 151ft stroke BS.4 steam catapults, a fully angled flight deck, Type 984 radar, CDS, DPT and an AC electrical system.
If Albion, Bulwark, Centaur and Hermes weren't laid down in the first place the resources put into these ships between their laying down and the end of the war would be used to accelerate the construction of the three Audacious class class too.
- I think Audacious would still be renamed Eagle but she'd be launched in 1945 instead of in 1946 and completed by the end of 1947 instead of late 1951.
- I think Ark Royal would have been launched in 1946 instead of 1950 and completed by the end of 1948 instead of early 1955.
- I think that the original Eagle would be renamed Audacious when the original Eagle was renamed Audacious. She would be launched in 1950 but completion would be delayed from late 1952 (as planned at the time of her launching) to early 1955 when it was decided to add interim angled flight deck and two 151ft stroke BS.4 steam catapults.
I want to be able to say that the Implacable and Indefatigable were modified to operate 30,000lb aircraft whilst under construction and that this included a single full-length hangar with 17.5ft high hangars instead of the one-and-a-half hangars with a height of 14ft. However, my guess is that the 30,000lb aircraft requirement would have to be brought forward at least 3 years to make that possible.
End of Part One
This raises a number of interesting questions.
Firstly design & development of carriers and carrier aircraft virtually stopped in May 1940 with the German invasion of France and the Low Countries as there were much higher priorities. It doesn't pick up again until the latter part of 1941 following the lessons of the first half of 1941 in the Med. The first product of that renewed effort is the Colossus / Majestic design and then the Audacious class during 1942.
In terms of aircraft design, aircraft max weight limits had been around 10,500lb until 1940 when they began to be relaxed to 12,500lb for the likes of the Firefly & Firebrand. But everything came out heavy. The Barracuda designed initially around 10,500lb came out at 14,250lb in production form in 1942. The same thing happened in the US. The Curtiss SB2C Helldiver design began at 10,200lb in Nov 1940 and in initial production form in Sept 1942 was at 16,600lb. The TBF-1 Avenger started at a max weight of 15,905lb in early 1942.
A technical committee reported in late 1942 about the future direction of naval aircraft development and realised that they would be even heavier if future and also larger dimensionally. Any ships built from then on would have a significant postwar life and the weight increases were likely to continue. Designs exceeding the 20,000lb limit begin to be requested in 1943. Fairey Spearfish (19,000lb limit came out at 22,000lb when it flew in 1945) & Short Sturgeon (24,000lb limit).
In 1942 the Admiralty realised that it will have to depend on the US for its aircraft for the forseeable future so will have to ensure its carriers can take them physically. The first recognition of this is that hangar heights are increased to 17.5ft to match the standard US hangar height. This can be seen as the designs of the 1942 carriers evolve during the year. 17.5ft allows the carriage of the F4U Corsair without clipping 8" from each wingtip. But looking further ahead the USN had in 1941 begun to develop a successor for the Avenger in the shape of the BTD Destroyer which was planned around 19,000lb.
So everything in 1942 points to a new higher weight limit above 20,000lb being needed but I don't believe that it would have been so clear to anyone in 1941.
But the changes to aircraft design also have an impact on the ships and the yards that were to build them.
Increasing the hangar height in the Audacious class design didn't happen until Nov 1942 and that needed an increase in beam to accomodate the extra topweight. In turn that meant the the original Eagle had to be moved from Swan Hunter to VA(Tyne) as the SH slip was no longer wide enough to build it. The design was also modified for 30,000lb aircraft.
If Centaurs were to be built in place of Colossus/Majestic then the issue of a yard's ability to accomodate them needs to be considered. Alexander Stephens & Sons on the Clyde built Ocean. They couldn't have built a Centaur. They didn't have a slip long enough (Ocean was the second longest ship they ever built. The longest was a tanker in 1962 after substantial investment in the yard post-war).
Then the question of build time. In late 1941 an Admiralty study estimated the build time for a fleet carrier at 46 months and a cruiser at 28 months. Early Colossus studies indicated a build time of 24-42 months depending on spec. The first 5, the wartime completions, averaged 30 months. If you build the bigger Centaurs to their better spec better suited to the post-war environment, the build time will inevitably increase. And as Centaur used a half set of Audacious machinery, instead of the already designed half set of cruiser machinery in a Colossus, there will inevitably be delays in laying them down. So at least the early completion dates will move to the right. But by how much? 6 months? 12 months?
And at Harland & Wolff Belfast if a Centaur version of Glory takes longer to build, then a Centaur version of Powerful which was laid down on the same slip the same day as Glory was launched, also gets delayed. H&W was incredibly busy with slips lying unoccupied for minimal periods of time in WW2.
If the Colossus were laid down as Centaurs in 1942 with longer build times, then the future of the historical Centaurs ordered in July 1943 becomes even more problematic. They were seen as post-war ships by the politicians and as necessary to operate the new larger post-war generation of aircraft by the professionals. So would they even be ordered in the first place? And if ordered would there even be the historical compromise of agreeing to lay down 4 and defer 4. Wartime money that can be better spent elsewhere. The professionals have even less reason to insist on their progression. And if not started construction in the first place no need to spend money on work to allow the slips to be cleared by taking them to the launch stage. An easy cull in Oct-Dec 1945.
And with the Centaurised Colossus in the yards for longer what is the labour effect on both them and other programmes in the yards? The Transport Ferry/LST(3) programme affected the major carrier yards like VA(T) causing delays to the original Eagle. But H&W, Hawthorn Leslie, Swan Hunter, Stephen Fairfield, and VA(Barrow) were all involved in building both types and the LST(3) was a high priority in 1944/45.
Over at Cammell Laird work on Ark Royal was held up in 1944 by the need to get Venerable completed and the commitment of the yard to submarine and destroyer programmes. If a Centaurised Venerable takes longer what are the knock on effects?
Moving to the end of the war, with delays to laying Centaurised Colossus ships down and longer build times the result is fewer wartime completions and more ships of the class further away from completion. Without the need for for the historic Centaurs to be worked on to clear the slips money is saved but that doesn't mean that it would automatically flow to completing the Theseus & Triumph (Warrior had been promised to Canada who were keen to get into the carrier game but were happy to see Magnificent, which was not that far from completion historically, laid up). Stopping work on Majestic, Leviathan, Powerful & Terrible historically saved about £3.2m. That sum would be greater if they were building as Centaurs.
So come 1948 the very best that can be hoped for are 5 Centaurised Colossus in service (with 1 each gone to Canada, France & the Netherlands) as historical, with the 6 Centaurised Majestics laid up as historical and probably in a less advanced state of completion and none of the historical Centaurs. Then the question is will Australia & Canada want to spend more money to get another carrier, albeit a larger one?
Another issue is that while we have talked about the greater deck strength to take the new generation of aircraft, we have not discussed the ability to launch and recover them. The BH.III hydraulic catapult was standard in WW2 and steadily upgraded to launch 16,000lb at 66 knots using the trolley or 20,000lb at 56 knots tail down (upgraded to 20,000lb at 66 knots tail down in 1949). The improved BH.5 began in prototype form in 1948 and entered service on Centaur in 1954 (prototype 20,000lb at 56 knots; production 30,000lb at 75 knots). Wartime arrester systems were upgraded for heavier aircraft between 1945 and 1950. But new systems as fitted historically to Eagle & the Centaurs didn't begin development until 1946.
So if there are any Centaurised Colosus around in 1948 they still need refitted to bring them up to the standard of the historical Centaurs in 1954. Do you then move then delay those refits to take advantage of steam catapults?
So the question then becomes one of whether delaying service entry of these ships even further is worth the post-war benefits of larger ships that still need considerable modernisation?
