Wi: Bigger and larger IMPLACABLE class Carriers

[1Big Rich]

Dumb question but why did they rebuild VIC and not just go straight to the two newest carriers?

If you mean Implacable and Indefatigable I don't know. However, I will hazard a guess is that they were newer, had seen less war service, were therefore in better condition and didn't need to be rebuilt before the earlier ships.

Also up to about 1948 the plan was to rebuild all 6 ships of the Illustrious type.

As often happens, older ships of a given class tend to get rebuilt/updated first, with newer ships scheduled later. At some point, the treasury or exchequer rears his ugly head, the rebuilds/updates for newer ships get cancelled, the now badly out-of-date newer ships get sloughed off to the breakers and the older modernized ships have to carry on.

So if that's true, why was Victorious first, and not Illustrious? War damage to Illustrious had warped her hull; with the flight deck as the strength deck, the hangar becomes a large void within the hull girder. Whether that could have been repaired with a full Victorious-style rebuild, I don't know, but I imagine it would have added considerable cost if possible.

I agree, the RN should have done Implacable and Indefatigable first, as they were the newest, had a four-shaft arrangement and had very little time on them. IIRC, Implacable was a training carrier post-war but even that isn't exactly hard service. With the rapid onset of navalized jets, operations from the Illustrious class would likely have been increasingly risky, plus the innovation of the angled deck changed carriers, so in my opinion the full rebuild was a necessity if the ships were to be kept or in service as carriers. To me. and I admit with hindsight, the wiser course would have been to rebuild the Implacables, make Indomitable (reboilered from 1948-50) an LPH/commando carrier and send Illustrious, Victorious and Furious to the breakers.

I have to admit, I do like the idea of the Implacables being re-cast as a 27,000 ton design. Even if their air group isn't much larger, they would have more stores for sustained operations, and thus would be even more valuable when rebuilt in the jet age.

My thoughts,

 

[Coulsdon Eagle]

Thoroughly recommend this for RN aircraft carrier studies: British Aircraft Carriers: Design, Development & Service Histories by David Hobbs.

It is a bit dry but for the history of designs and missed chances it is very much second to none. And despite the author serving on carriers he has no bias in favour of the RN.

 

[NOMISYRRUC]

The Royal Navy's aircraft plans in February 1951 according to From Vanguard to Trident by Eric J. Grove, page 73

(a) World War II armoured-hangar carriers

Implacable - to be modernized 1953-55; to relieve Eagle on refit 1956.

Indefatigable - to be modernized 1954-57.

Indomitable - harbour training 1953-57; modernization as training carrier 1957.

Victorious - modernization to complete 1954*; then trials carrier replacing Illustrious.​

(b) Colossus-class light fleet carriers

Vengeance - limited modernization to begin 1953 then to Category "C" reserve.

Warrior - limited modernisation 1952-53 then to Home Fleet.​

(c) Hermes-class-light fleet carriers

Hermes - to complete 1955 to modernized design; then to relieve HMS Glory.

Albion - to complete end 1952; then to relieve HMS Theseus.

Centaur - to complete early 1953; then to relieve HMS Triumph (as training carrier).

Bulwark - to complete 1954; then to relieve HMS Ocean.​

(d) Ark Royal-class fleet carriers

Eagle - to complete August 1951; to refit with steam catapult 1956

Ark Royal - to complete 1954.​

This was basically the "Revised Restricted Fleet" program, with two Colossus modernizations added after the decision to keep an extra light fleet carrier at sea. The Colossus modernizations were of a somewhat austere type, producing ships that could just operate the Gannet/Sea Venom combination but nothing more. It was not planned to give them such an extensive conversion as the Australians' HMS Majestic, which was allocated a valuable steam catapult and priority over Hermes at Vickers' Barrow yard. This was perhaps only politic, given the uneasiness of the Australians over the bargain they were getting thin their light fleet carrier purchases from the British.

To fly from these ships when they eventually appeared, some 300 front-line aircraft were planned for 1955, an increase of fifty over the original "Fraser Plan." By 1954-55 almost all first-line aircraft were to have gas-turbine engines, the actually planned number being 88 Sea Hawks, 48 Sea Venoms, 24 Wyverns, 112 Gannets (this Fairey type having finally defeated the Blackburn offering for the GR.17/45 specification at the beginning of 1951), and 28 Skyraider AEW aircraft (the only piston-engined type). The continued emphasis on fighters and ASW aircraft is noteworthy. This was an increase of over 50 percent compared to 1951, but it was still only the complement of three or four U.S. carriers. Nevertheless, the projected improvement in quality would greatly enhance Naval Aviation's capabilities, especially against Soviet submarines and jet bombers, the two major perceived threats in the Atlantic and Mediterranean respectively. As for second-...

*Projected loading for a modernized carrier: 20 Sea Hawk, 10 Sea Venom, 10 Wyvern, 10 Gannet and 4 Skyraider.[Total 54 aircraft.]

 

[Zheng He]

I agree, the RN should have done Implacable and Indefatigable first, as they were the newest, had a four-shaft arrangement and had very little time on them. IIRC, Implacable was a training carrier post-war but even that isn't exactly hard service. With the rapid onset of navalized jets, operations from the Illustrious class would likely have been increasingly risky, plus the innovation of the angled deck changed carriers, so in my opinion the full rebuild was a necessity if the ships were to be kept or in service as carriers. To me. and I admit with hindsight, the wiser course would have been to rebuild the Implacables, make Indomitable (reboilered from 1948-50) an LPH/commando carrier and send Illustrious, Victorious and Formidable to the breakers.

In the world of 20/20 hindsight I think that sounds like a great plan.

 

[1Big Rich]

I agree, the RN should have done Implacable and Indefatigable first, as they were the newest, had a four-shaft arrangement and had very little time on them. IIRC, Implacable was a training carrier post-war but even that isn't exactly hard service. With the rapid onset of navalized jets, operations from the Illustrious class would likely have been increasingly risky, plus the innovation of the angled deck changed carriers, so in my opinion the full rebuild was a necessity if the ships were to be kept or in service as carriers. To me. and I admit with hindsight, the wiser course would have been to rebuild the Implacables, make Indomitable (reboilered from 1948-50) an LPH/commando carrier and send Illustrious, Victorious and Formidable to the breakers.

In the world of 20/20 hindsight I think that sounds like a great plan.

I did say with hindsight Zheng. But as I pointed out above, the older ships usually get rebuilt first; it's obvious the Admiralty did not know Victorious was going to be so ungodly expensive,, then have that silly fire that just provided an excuse to get her disposed of early?

But following the time-line, if the Implacables are rebuilt, maybe they could be sold off sometime in the '60s to the likes of Australia or India in place of Light Fleets? Maybe Indomitable could be an ASW helicopter carrier for the Dutch or Canadian navies?

If the 1952 carrier gets into the building program, say a pair are built (four would be my ideal to incorporate an angled deck from the keel up), then the '60s carrier fleet could be 2 x 1952 CVs, Ark Royal and Eagle. If the late '60s defense cuts that got rid of Victorious still come around, the two Audacious class can go, and again, would be good candidates for foreign sale if reboilering were part of the deal. Assuming to CVA-01, the 1952 ships can sail on into the 1980s with 'through deck cruisers', and by then the USN is extending the life of old carriers with the Service Life Extension Program, so an RN version of SLEP might be possible to give them an extra 10-15 years.

My additional thoughts,

 

[NOMISYRRUC]

What if the IMPLACABLE class is built bigger and without the delay in otl?

To answer the second half of the question.

This is the table that I drew for the recent King George V class completed earlier thread.

​

If Implacable had been completed at the end of February 1942 she might have been able to take part in the Club Runs to Malta from March 1942 onwards.

She aught to be fully worked up in time to take part in Operation Harpoon and would definitely be fully worked up in time to take part in Operation Pedestal.

 

[NOMISYRRUC]

I meant Implacable and Indefatigable but I didn’t realize the original plan was to rebuild all six, which strikes me as a tad ambitious, particularly given how beat up some of the older ships were.

Rebuilding all 6 armoured carriers a tad ambitious! This is another table that was written for another thread.

 

[NOMISYRRUC]

What if the IMPLACABLE class is built bigger and without the delay in otl?

I think the OP is wrong.

I think it should have been, What if the Illustrious class was built bigger, in the intended numbers and completed on time? This is why.

In the first half of the 1930s the Admiralty calculated that the Fleet needed 360 aircraft.

The aircraft were to be carried by five aircraft carriers carrying 72 aircraft each. The ship designers reckoned that they could design a ship capable of carrying 72 aircraft on 22,000 tons. The 135,000 ton quota for aircraft carriers was still in force, which was enough for six 22,000 ton ships so there would be a spare ship to cover refits. However, the Admiralty was thinking of reducing British Empire's quota to 110,000 tons (i.e. five ships worth) by the next naval arms limitation treaty. The Admiralty also wanted to have the 27,000 ton limit on the size of aircraft carriers reduced to 22,000 tons, but the Second London Naval Treaty actually reduced it to 23,000 tons.

The result was the Ark Royal, ordered in the 1934-35 Estimates, laid down in 1935 and completed in 1938.

By 1935 it looked as if the tonnage quotas would be abolished by the next treaty so the aircraft required could be spread over a larger number of ships. Also the introduction of multi-role aircraft like the Swordfish had reduced the total number of aircraft required from 360 to 300. The new plan was to spread them among eight aircraft carriers. That is Ark Royal (now rated at 48 aircraft) and seven ships carrying 36 aircraft each. The 36 aircraft ship became the Illustrious class.

The 8 aircraft carriers carrying 300 aircraft between them were to operate with the main fleets. The abolition of the tonnage quotas also made it possible to build trade protection carriers. However, they weren't intended to escort convoys in the North Atlantic. They were intended to help the cruisers find and destroy surface raiders on the trade routes. As such they had to carry enough aircraft for the required search pattern and for a torpedo strike capable of sinking a cruiser sized warship. The design studies produced ships costing about £3 million, which wasn't much short of the £4 million estimated for the Illustrious. Therefore it was decided to build more Illustrious class ships to fulfil this role and the trade protection ship planned for the 1936-37 Naval Estimates was replaced by HMS Victorious.

This crystalised into a requirement for 14 aircraft carriers as follows:

8 ships for the main fleets
5 ships for trade protection
1 ship for training​

The 14 ships would be made of 10 Illustrious class ships, Ark Royal, Courageous, Glorious and Furious.

The 10 Illustrious class ships were to be built at the rate of 2 per year from the 1936-37 Navy Estimates onwards. That is:

1936-37 - Two ships to be laid down in 1937 and completed in 1940 (Illustrious and Victorious were ordered)
1937-38 - Two ships to be laid down in 1937 and completed in 1940 (Formidable and Indomitable were ordered)
1938-39 - Two ships to be laid down in 1938 and completed in 1941 (but only one ship, Implacable, was ordered)
1939-40 - Two ships to be laid down in 1939 and completed in 1942 (but only one ship, Indefatigable, was ordered)
1940-41 - Two ships to be laid down in 1940 and completed in 1943 (some sources say Ark Royal (ex-Irresistible) was ordered under this programme)​

Although Illustrious and Victorious were ordered in the 1936-37 Navy Estimates a clause in the Second LNT meant that they had to be laid down one year after their orders were announced.

The 1938-39 and 1939-40 building programmes had to be cut because the Rearmament Programme was creating demand pull inflation and a balance of payments deficit. Two of the ships cut were the second aircraft carriers from the 1938-39 and 1939-40 estimates. I don't have the proof, but I suspect that the pair of ships planned for the 1938-39 Estimates were to have been laid down in 1938 for completion by the end of 1941. If I am right it means that Implacable was laid down at least 6 months behind schedule.

As far as I know only one aircraft carrier was ordered in the 1940-41 Navy Estimates and this ship became the ship laid down in 1943 as Irresistible and completed in 1955 as Ark Royal. Again, AFAIK Eagle (ex-Audacious) and the other Eagle were both ordered as part of the 1942-43 Programme. On that basis Irresistible should have been laid down before Audacious. I don't know why they were laid down in the wrong order. I suspected that it was because she was suspended during the invasion scare of 1940, then by the need to concentrate on convoy escorts and merchant ships, and then finally while she was redesigned into what became the Audacious class.

I did the above from memory so it might not be 100% accurate. However, it's close enough.

To be continued...

 

[Zen9]

It's certainly possible to build a larger carrier as a follow on design from Ark Royal. Studies were done.

 

[Peg Leg Pom]

If they'd kept the 27,000 ton limit the Armoured Carriers could have had the same air group as Ark Royal.

 

[Zen9]

Hmm......
Sketch D 1934 CV
Length 775ft, Beam 87ft, SHP 116,000 = 32kts
Flight Deck of 800ft, but potentially another 25ft is easily added in overhang at the stern and in theory she could be taken to 850ft
Single hanger deck, double platform lifts
Single flying off deck.
Armour around magazines sufficient to resist 500lb bombs and 4.7" fire.
Full accommodation for 72 aircraft.

Hmm......shorter and narrower than Courageous, she'd fit the Portsmouth Locks, Davenport No.10, Gladstone at Liverpool and Rosyth.

Arguably a process of a limited armoured magazine CV is going to increase in beam back to Scheme C 1931 study under pressure to increase internal space and improve stability.

Such carriers would be more easily damaged from attacks, but would deliver more capability and serve as a better basis for a next generation effort.

Under such circumstances the Irresistible-Audacious process could result in the ideal Davenport No.10 Limited CV of 850ft FD, 800ft LWL, BWL 112ft and Displacement maximum of 52,000tons.
Alternatively it's possible for a narrower 104ft BWL option based on a shortend Hood-type hullform for 42-45,000tons

That would seriously transform the process post WWII as it would the Malta process, since repeat of such No.10 limited CVs is not just a simpler pragmatic process, but is 12ft of flight deck over the lower limit of the requirements of the Oct 1944 meeting. Additional overhang could add some 20ft at the flight deck if necessary.

It would make the rebuilding of such successor Davenport No.10 Limited CVs after 1950 a viable and effective process.

This would apply serious pressure to improving military drydock facilities in the UK post WWII.
Arguably enlarging Lock A at Portsmouth and a new dock on the purchased land at Plymouth (north of current facilities) would suffice.
Such a process having with rebuild of the later CVs, some 30 years to be achieved before needed for the next gen CVA fleet.

 

[NOMISYRRUC]

If they'd kept the 27,000 ton limit the Armoured Carriers could have had the same air group as Ark Royal.

I've not read @Zen9's posts on the subject.

However, at the end of the war the OTL 23,000 ton armoured carriers did have air groups comparable to Ark Royal.

Illustrious, Formidable and Victorious all had 54 aircraft, which IIRC, were 36 Corsairs and 18 Avengers.

Indomitable had 65 aircraft.

Implacable and Indefatigable had 81 aircraft.
​

This was due to the adoption of deck parks and because monoplanes could be folded into smaller packages than biplanes.

An Implacable enlarged to 27,000 tons could take two full-length hangars. However, I think they would only be 16 feet high, like those on Ark Royal and the 3 single-hangar ships.

Furthermore, the extra 4,000 tons might be better used in improving the accommodation for the ground crew, more ordnance, more fuel and more spare parts because these ships will only be able to operate the extra aircraft effectively if they have the required ground crew, ordnance, fuel and spare parts.

 

[NOMISYRRUC]

Also, the Colossus' as Majestic's from the start.

If the requirement to operate 30,000lb could be introduced sooner then they would have been built as Centaurs from the start.

The extra labour and materials would come from suspending the Swiftsure class cruisers and if necessary Vanguard.

If that had been done it's possible that the OTL Centaur class would not have been laid down in the first place and the resources put into speeding up the 3 Audacious class ships. IIRC all 3 ships were behind schedule due to a shortage of materials and labour.

Unfortunately I think Implacable and Indefatigable will be too advanced in 1942 to modify them to operate 30,000lb aircraft while building.

 

[The Wooksta!]

Having four Audacious class (and zero CVLs!) in 1945-50 may push faster development of jets. So, Ark Royal and Eagle deploy to Korea in 1951 with swept-wing Sea Hawks. That, combined with WW2 experienced pilots should match up against the MiG-15.

Even better would be the Hawker P.1081 with the swept tailplane, https://en.m.wikipedia.org/wiki/Hawker_P.1081

Of course, without the CVLs, the lesser navies won’t have discount carriers to buy. What does India, Australia, Canada and the Latams do?

The P.1052 got a fully swept tailplane at a later date, the second prototype was modified with an all through jetpipe to become the P.1081 - IIRC, the P.1068 was basically a Sea Hawk with an all through jetpipe and a swept fin but unswept T-tailplane. The P.1062 is basically a P.1081 with a delta T-tail. The one the Navy should have got was the navalised P.1087, with folding wings and taller fin.

Somewhere I have drawings of all the Sea Hawk based projects Hawkers had drawn up. There are some really interesting ones I'd like to try and kit bash at some point, especially the two seat trainer (think Sea Hawk with Vampire T-bird canopy) but extrapolated onto a P.1081 airframe...

 

[NOMISYRRUC]

I once suggested in another thread that Rolls Royce should have been given the Barnoldswick jet engine factory from the start because I thought that it would result in British jet engines going into production a year or two earlier than OTL. I also thought that more powerful jet engines like the Derwent and Nene would be available sooner and that the Clyde gas turbine would be available a year or two sooner as well.

@Just Leo poured scorn over the idea as only he could.

Two of the reasons why I suggested doing so were that I thought that Specifications F.1/43 and F.2/43 would have produced aircraft similar to the Attacker and Sea Hawk instead of the OTL Spifeful/Seafang and Sea Fury.

The next step would be swept-wing versions, equivalent to the OTL Supermarine Type 510 and Hawker P.1081, which would go into service in place of the OTL Attacker and Sea Hawk.

 

[Zen9]

I once suggested in another thread that Rolls Royce should have been given the Barnoldswick jet engine factory from the start because I thought that it would result in British jet engines going into production a year or two earlier than OTL. I also thought that more powerful jet engines like the Derwent and Nene would be available sooner and that the Clyde gas turbine would be available a year or two sooner as well.

@Just Leo poured scorn over the idea as only he could.

Two of the reasons why I suggested doing so that I thought that Specifications F.1/43 and F.2/43 would have produced aircraft similar to the Attacker and Sea Hawk instead of the OTL Spifeful/Seafang and Sea Fury.

The next step would be swept-wing versions, equivalent to the OTL Supermarine Type 510 and Hawker P.1081, which would go into service in place of the OTL Attacker and Sea Hawk.

The flipside to that is that more work on reheat would deliver higher performance centrifugal jet powered aircraft.
Other countries proved this with swept wings.

But uk research was held back on swept wings and reheat.

 

[PMN1]

I once suggested in another thread that Rolls Royce should have been given the Barnoldswick jet engine factory from the start because I thought that it would result in British jet engines going into production a year or two earlier than OTL. I also thought that more powerful jet engines like the Derwent and Nene would be available sooner and that the Clyde gas turbine would be available a year or two sooner as well.

@Just Leo poured scorn over the idea as only he could.

Two of the reasons why I suggested doing so were that I thought that Specifications F.1/43 and F.2/43 would have produced aircraft similar to the Attacker and Sea Hawk instead of the OTL Spifeful/Seafang and Sea Fury.

The next step would be swept-wing versions, equivalent to the OTL Supermarine Type 510 and Hawker P.1081, which would go into service in place of the OTL Attacker and Sea Hawk.

Got a link to that

 

[NOMISYRRUC]

Got a link to that

Is that for how I hoped it would help the development of British civil and military aircraft 1945-55 or for @Just Leo's scornful comments.

 

[PMN1]

Is that for how I hoped it would help the development of British civil and military aircraft 1945-55 or for @Just Leo's scornful comments.

Both......particularly the latter.....

 

[NOMISYRRUC]

[Snip]What if the Illustrious class was built bigger, in the intended numbers and completed on time?

[Snip]To be continued...

POD 1935

Instead of the ten 23,000 ton aircraft carriers carrying 36 aircraft each, the Admiralty decided that it required ten 27,000 ton ships carrying 72 aircraft each.

27,000 tons was the maximum possible displacement for an aircraft carrier under the Washington and Fist London Naval Treaties. ITTL it was carried over into the Second London Naval Treaty instead of being reduced to 23,000 tons.

The resulting ship was an enlarged Implacable, rather than an enlarged Illustrious because its machinery produced 148,000shp driving 4 shafts rather than 111,000ship driving 3 shafts.

The enlargement was to allow the ship to have two full length hangars, which were 62 feet wide and at least 16 feet high. These are the hangar dimensions on the OTL ships.

Except that I have seen some drawings of the Audacious design, which show that the length of the hangars was 364ft between the lifts and that the upper hangar and an extension of 48 feet in front of the forward lift, which made the total length up to 412 feet.

The ship was to be welded, be fitted with high-pressure boilers and an AC electrical system instead of the normal DC to save weight.

In common with OTL the 10 ships were to be ordered at the rate of 2 per year, starting at the 1936-37 Navy Estimates. Eight of the ten ships were ordered before September 1939 as follows:

1936-37 - Illustrious and Victorious
1937-38 - Formidable and Indomitable
1938-39 - Invincible and Inflexible
1939-40 - Implacable and Indefatigable​

The two ships planned for the 1940-41 building programme were eventually built as the OTL Audacious class aircraft carrier Ark Royal and a fourth Audacious class which was built in place of the OTL battleship Vanguard.

To be continued...