Late 70s RN fleet carrier design?

[Rule of cool]

Depends on state of the budget and inter-service rivalry, but you can always put RAF jets on the carrier, if you can't increase the number of fleet air arm squadrons for whatever political reasons. But consider that the political situation is very different, since you already have 2 or 3 CVA carriers with full complements, plus backup and shore squadrons, etc.

I don't know how well known it is, but from the 70s the RAF formed TACSMO as the RN wound down it's carrier force specifically for maritime operations in the North Atlantic. There ended up being quite a decent number of sqns allocated to TACSMO, IIUC 2 Phantom sqns, 2 (at one point 3) Buccaneer sqns, the V bomber MRR sqn and I think other cats and dogs. Added to this is a couple of Sea Harrier sqns actually on the small RN carriers.

In my mind if the MoD is maintaining so many maritime role sqns with (ostensibly) carrier capable aircraft then putting them on ships other than small ASW carriers isn't a huge leap.

 

[NOMISYRRUC]

Re the comments about the CVA.01 Batch 2 with the steam turbines replaced by 6 Olympus GTs driving 3 shafts.

This GT-powered variant of CVA.01 had been suggested several times in this forum and on alternatehistory.com (by me) and (originally) by @Riain on alternatehistory.com. The reply to those suggestions was that (unless turbo-electric drive was used) the primary disadvantage of the design would more than cancel out the advantages.

Said primary disadvantage (mentioned in this thread by @Hood) was that the trunking and exhausts for the GTs would reduce the size of the hangar and require a much bigger island superstructure which would reduce the size of the flight deck. So the air group would be smaller.

I countered that the "ship impact" (if that's the right expression) would be less as it's 50% more trunking and exhausts than Invincible (due to having 50% more Olympus GTs) in a hull with nearly 175% more displacement (19,500 tons v 53,000 tons).

One of the things I liked about the GT-powered CVA.01 was that it needed a smaller crew than the ST version. Which, is the silver lining in the cloud, because the smaller air group means an even smaller smaller crew.

The secondary disadvantage of the GT-powered CVA.01 was that the much hotter exhaust gas would play havoc with the Type 988 radar if it was still mounted atop a mack (as in the ST version) and therefore would have to be mounted above the bridge (à la the Type 1022 on Invincible). AFAIK that reduces the radar horizon and the massive funnels behind it would stop the radar seeing dead astern.

 

[Rule of cool]

Given the first job for the GT's exhaust would be to go through heat exchangers to create steam would this process take some of the 'energy' out of the GT's exhaust and reduce the trunking requirements at all?

Other than that, I agree with the notion that exhaust for 6 GTs would have significantly less 'ship impact' on a ~55,000t ship than 4 of the same GTs would have on a ~20,000t ship. In any case given the RN's thoughts on full-width gallery decks the British carrier was always going to have a big island, the steam powered CVA01's island was a whopper!

 

[NOMISYRRUC]

I don't know how well known it is, but from the 70s the RAF formed TASMO as the RN wound down it's carrier force specifically for maritime operations in the North Atlantic. There ended up being quite a decent number of sqns allocated to TASMO, IIUC 2 Phantom sqns, 2 (at one point 3) Buccaneer sqns, the V bomber MRR sqn and I think other cats and dogs. Added to this is a couple of Sea Harrier sqns actually on the small RN carriers.

In my mind if the MoD is maintaining so many maritime role sqns with (ostensibly) carrier capable aircraft then putting them on ships other than small ASW carriers isn't a huge leap.

It bloody should be well known considering how often I've ranted about it.

Link to one of my rants about the RAF's TASMO force.

FWIW (1) there were these in addition to what @Rule of cool said.

• The Sea King ASW helicopter squadrons that operated from the Invincible class IOTL, which would be the Sea King ASW helicopter squadrons that operated from the strike carriers ITTL.
• And No. 8 Squadron, RAF, which took the place of the Gannet AEW.3s in 849 NAS.
  • The 12 Shackleton AEW.2s were fitted with APS-20 radars taken from redundant Gannet AEW.3s.
  • And no Nimrod AEW fiasco ITTL.
    • The money saved on that (and building the Invincible class) would go a long way towards paying for CVA.02 and CVA.03.
  • Unless.
    • The OTL Nimrod AEW fiasco of OTL is replaced by a HS Brough P.139 fiasco ITTL.
• The Sea King AEW.2 that were hastily brought into service as the Falklands War ended and from 1984 equipped the reformed 849 NAS.

The RAF's TASMO force, the Sea Harrier squadrons and the Sea King squadrons were large enough to form two 1970s Ark Royal size air groups and a training group of 700-series squadrons. The operational air groups would be brought to full strength by breaking up the training group as and when required.

Though, strictly speaking there wouldn't be the Sea Harriers and AEW Sea Kings, so the personnel and money could be used to enlarge the Phantom, Buccaneer and E-2Cs squadrons.

That fits with my guess is that the maximum number of strike carriers the UK could support was three (taking the place of the Invincible class and the TASMO force) of which two would be in commission and the third would be in refit/reserve, which was what happened to the Invincible class after HMG decided to cancel the sale of Invincible to Australia.

FWIW (2) there were never more than 2 Buccaneer maritime strike squadrons. The rant I've provided the link to explains what happened in more detail.

 

[NOMISYRRUC]

Given the first job for the GT's exhaust would be to go through heat exchangers to create steam would this process take some of the 'energy' out of the GT's exhaust and reduce the trunking requirements at all?

FWIW that's another thing you've suggested before.

I can't remember if it was you, me or both of us that asked if having donkey boilers to generate the steam for the catapults would affect availability rates. That is, having to maintain them would reduce the higher availability rates that GT ships have.

Also you claimed (and I agree) that a GT ship would be cheaper to operate as it aged than a ST ship and have a longer service life. Would the donkey boilers for the steam catapults increase the operating costs and shorten service life?

What was "all my own work" was that a GT ship (especially with turbo-electric drive) could generate tons of electricity that might be used for ELAS catapults. Furthermore, I suggested that there might be some synergy with the UK's 1970s hovertrain project which also used Linear Induction Motors. My suggestion went down like the proverbial lead balloon. The replies were to the effect that the USN is finding it hard enough to make ELAS catapults work in the 2020s, let alone in the 1970s.

There was this thread on Internal Combustion Catapults.

Link to the OP of the Aircraft Catapults thread.

Might they be the solution? Or do they have disadvantages that I don't know about, which make them worse than steam catapults?

Other than that, I agree with the notion that exhaust for 6 GTs would have significantly less 'ship impact' on a ~55,000t ship than 4 of the same GTs would have on a ~20,000t ship. In any case given the RN's thoughts on full-width gallery decks the British carrier was always going to have a big island, the steam powered CVA01's island was a whopper!

Something that occurred to me when I was writing Message 42 was that the depth of the hull will be a factor on the extra volume of the trunking and exhausts of the GTs vis-à-vis the STs. Was the CVA.01s hull deeper than the Invincible's hull? If it was deeper then the trunking and exhausts will consume more of the hull than I estimated.

The island on CVA.01 was much shorter than the island on the Invincible class. See below.

https://www.reddit.com/r/WarshipPorn/comments/195jy0k/the_development_of_british_aircraft_carriers_from

View: https://www.reddit.com/r/WarshipPorn/comments/195jy0k/the_development_of_british_aircraft_carriers_from/#lightbox

It was somewhat wider though. The funnels on Invincible seem to be about half the length of the island on CVA.01. Our guess is that the funnels on a GT powered CVA.01 will be 50% larger than the funnels on Invincible.

OTOH (1) @Hood wrote in Message 18 that the 4 Olympus GTs on the Invincible class produced 97,000 driving 2 shafts. So the GT CVA.01 theoretically produces 145,500shp driving 3 shafts. Do they need to be that powerful as the steam turbine version only produced 135,000 shp? Derating the 6 Olympus engines to a combined 135,000 would reduce the size of the trunking and exhausts and reduce the maximum temperature of the exhaust gas too?

@Hood also wrote that endurance might suffer. However, IIRC gas turbines have better fuel consumption than steam turbines of equivalent power. Therefore, endurance may be greater. Especially, if the GTs are derated to a total of 135,000shp. Plus, if having GTs do have better fuel consumption than STs, what's saved can be used to keep the aircraft flying for longer before refuelling, rather than increasing the endurance.

OTOH (2) would the extra 10,000-odd shaft horse power make the GT version significantly faster? The extra WOD may be useful.

@Hood also wrote.

Saving on weight compared with steam propulsion might fully compensate.

Although the context of that statement was in relation to the donkey boilers and extra steam generators, it might also mean that space and weight saved could be used to carry more fuel and ordnance.

I think others have said, in other threads, on this subject, that some things that were above the hangar deck (including in the superstructure) can be fitted in the extra space below the hangar deck. That cancels out some the extra trunking and exhausts that a GT ship requires. Which if correct, the reduction in the floor areas of the hangar and flight deck would not be as great as we fear.

Plus, as we think that bigger dry docks will be available when CVA.02 and CVA.03 are designed so their hulls can be longer. AFAIK as long as a compensating increase in beam isn't required a longer ship doesn't require more powerful machinery to achieve the same maximum speed. Which if correct can be used to have a longer hull (with a longer flight deck and hangar) without more powerful machinery, which would require even more trunking and exhaust, which would cancel out the advantages of a longer hull.

 

[Martes]

That fits with my guess is that the maximum number of strike carriers the UK could support was three (taking the place of the Invincible class and the TASMO force) of which two would be in commission and the third would be in refit/reserve

In some sense this puts an interesting limitation on this here premise.

IF it is considered, Britain does build 2-3 CVA-01, a replacement design a mere decade afterwards is way too early. And where are 2 units, designing a third from scratch is a terrible waste and would cause a lot of headache with maintenance and deployment rotation.

On the other hand, if the CVA program does get cancelled, and Invincibles are laid down, but upon arrival of conservative government it is decided to restore the carrier program, the timing may just be right. Invincibles then would get their role as escort cruisers, just as they should've been.

 

[NOMISYRRUC]

The plan....let's be generous, was originally 4 new CV of what became CVA-01 design.
This shrunk and by cancellation was still expected to be two such vessels.

So the simplest answer is CVA-02 or ideally CVA-03.
All were expected to complete in the 70's and succeed the 40's and 50's vessels.
Obviously budgetary and strategic considerations changed this.

The most obvious change would be Seawolf instead of Seacat.
Internally magazine and maintenance for Martel for Buccaneer, the expensive recon pod for the F4.
CVA-03 might be delayed for keeping Eagle in service but an early 80's succession would be expected.

So this vessel might be modified for GWS.31 with Type 1030 and Internally facilities for Skyflash, Sea Eagle and later ALARM.

Now IF......if CVA-01 design on service entry is deemed inadequate and CVA-02 modified doesn't fix those issues. Then a new design maybe forthcoming.

I'm regarding CVA.02 and CVA.03 as the Invincible class flagship facilities, weapons, sensors and other electronics like the ADAWS in a CVA.01 (or larger) hull. Therefore, its GWS.30 Sea Dart (like the Invincibles), Type 1022 (like the Incincibles) and 3 Phalanx (like the Invincibles).

According to the Ian Allan book about the Invincible class they did have 3 GWS.25 Sea Wolf systems until Lord Carrington deleted them. Therefore, I fear that it's rather likely that they would be fitted "for but not with" Sea Wolf. He thought that there would be plenty of Sea Wolf armed frigoyers to screen them and to be fair, there were plenty of Sea Wolf armed frigates when the 14 Type 22s and 16 Type 23s were completed, but it was exactly the opposite in the spring of 1982, when there were only a handful of Type 22s and Sea Wolf Leanders.

As I think they'd be built instead of the Invincible class the 2 ships (and CVA.01) would have their Sea Darts removed during their mid-life modernisations. Although, they might not have a Sea Dart in the first place. One of the lessons of CVA.01 may be that a longer flight deck and hangar were better than having an area defence SAM on the stern as all other things being equal there'd be 14 Type 42s and one Type 82 armed with Sea Dart to escort them.

 

[NOMISYRRUC]

IIRC in the CVA01 design process the CVA01 became a 53,000t, 3-shaft ship because having 4 shafts and 58,000t didn't provide enough tactical benefits to justify the cost. Perhaps a decade later, with the Spey coming into service 4 shafts and 58,000t might become better value for money. Indeed by then the British might be able to build a 60,000t carrier.

FWIW (according to Norman Friedman) 3 shafts allowed a better torpedo defence system than 4 shafts (3 longitudinal compartments instead of 2) and IIRC that was an important reason why it was designed with 3 shafts instead of 4.

 

[NOMISYRRUC]

On Buccaneers built.
Forty-six built between 1973 and 1977, plus three for weapons trials work.
Had RN carrier remained in operational planning beyond the early 70's. Then we can envision a new S.3 variant put into production from the mid-to-late 70's. Likely using a lot of Tornado avionics.
Production line could have remained open for much longer.
Temptation there to either move to uprated Spey development or replace with a RB.199 variant.

It all would depend on the bigger picture.

It may help that.

Depending upon the source as many as 12 S.2s ordered for the RN were cancelled in the late 1960s and there were proposals to convert the surviving S.1s to S.2s. The first probably happens ITTL and the second might happen ITTL. That increases the pool of aircraft that can be rotated through the operational squadrons and second-line units so they take longer to wear out.

Also part of the POD may be that the RAF is forced to buy Buccaneer (possibly with better avionics) instead of TSR.2 and F-111K. If the RAF Buccaneers do have the more advanced avionics the RN Buccaneers may be built with the too. The bigger and longer production run should benefit both services by reducing the production and running costs of their Buccaneer fleets.

Though the better avionics would be more expensive. IIRC delays and cost overruns in TSR.2s avionics were a major portion of the delays and cost overruns in the TSR.2 project as a whole. There's a video on the internet of a lecture on the TSR.2 in which the lecturer estimated that the full-spec TSR.2 avionics wouldn't be ready until the middle 1970s. If he was correct, then what may happen is that all the Spey-Buccaneers built for both services to circa 1973 were built to the OTL S.2 standard and the aircraft built after that date have the avionics package that the RAF wanted in the first place.

 

[NOMISYRRUC]

The RN wouldn't be in the market for a new carrier aircraft in the late 70s, the Buccaneer and Phantom would be ripe for mid life updates and the USN would be well underway with the Hornet. I doubt they'd go down any STOVL route hoping an aircraft would appear.

FWIW I agree.

It's likely that more Buccaneers are built for the RN to the OTL end of production in 1977 and more will be built for the RAF to that date, if as I hope, the POD is that the RAF is forced to buy the Buccaneer instead of TSR.2 and F-111K. Production may continue beyond 1977 to replace attrition ITTL and is even more likely if the RAF is forced to buy more Buccaneers instead of the TSR.2 and F-111K.

All the F-4Ks built IOTL go to the RN ITTL. IIRC that was enough to support a squadron for Ark Royal, a squadron for Eagle and the usual proportion of second-line units. That fits my other rant about 3 strike carriers with 2 in commission and the third in refit/reserve with 2 under-strength operational air groups and one training group which if required could be broken up to bring the operational groups to full strength.

Because of the above my guess is that the same number of F-4Ks would be built ITTL. Therefore, if the RN runs out of them due to higher than expected attrition and/or them being kept in service far longer than envisaged in 1964 the RN will have to do what the RAF did IOTL and buy used F-4s with J79 engines from the USN.

My guess is that the eventual replacement for both aircraft will be the Hornet or Super Hornet rather than Tornado or Typhoon.

 

[Rule of cool]

In some sense this puts an interesting limitation on this here premise.

IF it is considered, Britain does build 2-3 CVA-01, a replacement design a mere decade afterwards is way too early. And where are 2 units, designing a third from scratch is a terrible waste and would cause a lot of headache with maintenance and deployment rotation.

On the other hand, if the CVA program does get cancelled, and Invincibles are laid down, but upon arrival of conservative government it is decided to restore the carrier program, the timing may just be right. Invincibles then would get their role as escort cruisers, just as they should've been.

I imagine the premise to not include a continuous build of a class of carriers, the 1952 carrier will see to that. It would likely enter service in 1959-60 at the expense of the Victorious rebuild, Eagle would get her early 60s rebuild, CVA01 would be the replacement for Ark and this 1978 carrier would be the replacement for the Eagle by the early 80s. The RN wouldn't need another carrier until the early 90s to replace the 1952 carrier, leading to 5-year build gaps between big carriers that take 7 years to build.

 

[NOMISYRRUC]

Australia considered CVA01 and an Essex class in 1965 and the RN considered a Forrestal sized ship as well as the many beloved medium carriers during the CVA01 process. Organisations consider all sorts of things in order to establish a left and right of arc, that doesn't mean they ever thought they'd get them, or even wanted them.

I've read some of the RAN's files. IIRC finding the extra men was as due to them having larger crews than Melbourne was more of a stumbling block than finding the money to buy the ships and their aircraft.

FWIW GT machinery requires less men (and or/women) than ST machinery of the same power so the gap between Melbourne and a GT CVA.01 would be less than the gap between Melbourne and OTL CVA.01 with steam turbines. However, it wouldn't be enough to have Australia buy CVA.02 in 1981 in the TTL version of the Knott defence review. However, the Thatcher Government would be trying to make Australia buy CVA.01 as that's the oldest ship ITTL while it would want to keep the newer (and cheaper to operate) CVA.02 and CVA.03.

 

[NOMISYRRUC]

Another thing I'm interested in is the 'steel is cheap, air is free' mantra that I think is linked to GT propulsion, given the CVA01 was designed to politically imposed limits.

Another of my rants.

E.g. the standard displacement of CVA.01 was in the region of 3 times more than Invincible, but it wouldn't cost 3 times as much due to them having (roughly) the same flagship facilities, fixed armament, sensors and other electronics like ADAWS. Also if it's the GT version of CVA.01 the machinery only costs 50% more and its cheaper to run due to the reduced personing requirements and standardisation with the many RN and foreign ships that used the Olympus gas turbine IOTL.

 

[Rule of cool]

Another of my rants.

E.g. the standard displacement of CVA.01 was in the region of 3 times more than Invincible, but it wouldn't cost 3 times as much due to them having (roughly) the same flagship facilities, fixed armament, sensors and other electronics like ADAWS. Also if it's the GT version of CVA.01 the machinery only costs 50% more and its cheaper to run due to the reduced personing requirements and standardisation with the many RN and foreign ships that used the Olympus gas turbine IOTL.

My thoughts on steel is cheap and air is free is that it has limits that might be quite firm depending on the context and the 53,000t, CVA01 had as cheap steel and free air much as possible on 3 shafts. To get more cheap steel and free air into the hull would need another (expensive) shaft for the propulsion.

IIUC from about the 60s the hull was about 1/4 of the ship cost, propulsion was about 1/4 of the ship cost and everything else like sensors, weapons, comms etc was 50% of the cost. While a carrier might be light-on for sensors and weapons for its size it does have a lot of expensive stuff like catapults, arrestor gear, aircraft lifts, JBDs, aircraft refuelling gear etc etc etc.

I agree about the small marginal cost over an Invincible, it was politics not money that saw the downgrading of the RN from the 60s.

 

[EwenS]

Depends on state of the budget and inter-service rivalry, but you can always put RAF jets on the carrier, if you can't increase the number of fleet air arm squadrons for whatever political reasons. But consider that the political situation is very different, since you already have 2 or 3 CVA carriers with full complements, plus backup and shore squadrons, etc. And I still advocate for carrier-based Tornados for 80's.

Well first the RAF has to have carrier capable aircraft (compare the RN Phantom FG.1 with the RAF Phantom FGR.2) and secondly the RAF pilots need additional training to allow them to land an aircraft on a carrier deck.

IIRC there were some issues back in the day with RAF pilots who didn't want to go to sea on Ark's squadrons. "If I wanted to go to sea I'd have joined the FAA" type attitudes.All that time away from family wasn't something they felt they had signed up for.

 

[Hood]

@NOMISYRRUC

On the subject of GT uptakes and islands:
I think the ultimate solution will be that adopted by the latest generation of GT-powered CVS's and LHA's (QE's, Trieste) would be the twin island solution.

The RN actually had a strong latent tradition of this pre-CVF - the Maltas, the 1952 designs and arguably CVA-01's island was a semi-twin given that its lower mid-section was basically tunnels/vehicle hangarage.

I don't know enough about exhaust heat-exchangers to say whether they could generate sufficient steam. I don't think that the capacity of CVA-01's wet accumulators has been stated but US carriers of the time had 16,000gal capacity accumulators that held 8,000gal of boiler feed water or steam-generated feedwater in nuclear ships).
Nobody has ever built a GT-powered steam catapult carrier and probably never will now. It is certainly not ideal.

On the other hand, given you have two steam carriers plus Bristol and Counties and Leanders still in service, there is no reason why the Admiralty wouldn't just specify a repeat CVA-01 steam powerplant and rely on the existing stoker manpower, since there will be greater need to keep training going etc. if in this scenario its planned to keep the 1952 Carrier and CVA-01 running into the late 1980s.

 

[zen]

1960 comparison studies.
68,000ton CV, 59 aircraft + 4 ASW helicopters.
1004ft flight deck, 964ft waterline length, 190ft flight deck width and 128ft waterline beam. 33.5ft draught.
3 lifts, 3 catapults (225ft), 3 wires

160,000shp = 30kts clean, 28kts dirty.
So assuming plants, shafts and props built for 70,000shp (USN Kittihawk had 4 such for 280,000shp).
Then driving such a vessel to 34kts seems achievable.

 

[Rule of cool]

On the other hand, given you have two steam carriers plus Bristol and Counties and Leanders still in service, there is no reason why the Admiralty wouldn't just specify a repeat CVA-01 steam powerplant and rely on the existing stoker manpower, since there will be greater need to keep training going etc. if in this scenario its planned to keep the 1952 Carrier and CVA-01 running into the late 1980s.

Something else I keep thinking is the big American ships of the period, the Tarawa class, were steam powered just as the USN was embraced GTs in a big way with Spruances and OHPerrys. Perhaps steam is simply better for such large ships in the 70s.

 

[NOMISYRRUC]

In some sense this puts an interesting limitation on this here premise.

IF it is considered, Britain does build 2-3 CVA-01, a replacement design a mere decade afterwards is way too early. And where are 2 units, designing a third from scratch is a terrible waste and would cause a lot of headache with maintenance and deployment rotation.

On the other hand, if the CVA program does get cancelled, and Invincibles are laid down, but upon arrival of conservative government it is decided to restore the carrier program, the timing may just be right. Invincibles then would get their role as escort cruisers, just as they should've been.

The first paragraph of the OP is.

I think the RN's 1952-53 and CVA01 designs are pretty well known around this site. They fall pretty much into when the RN needed a new fleet carrier, so if the British built a 52 carrier from the early/mid 50s and CVA01 from 1966 to keep a 3 carrier force they'd need to lay down a new fleet carrier in the late 70s.

My interpretation of that is that the 3 strike carriers are a Phantomised Eagle or Ark Royal, the 1952 Carrier and the OTL CVA.01 (with STs) built from the late 1960s to early 1970s.

CVA.02 is required to replace the Phantomised Audacious class ship in the late 1970s. CVA.03 is required to replace the 1952 Carrier in the first half of the 1980s. Both could be kept in service for longer, but they'd cost more to operate and have lower availability rates than new ships, especially if the new ships have gas turbines instead of steam turbines.

The Invincible class aren't built in any form ITTL. The money that paid for their building IOTL pays for CVA.02 and CVA.03. The money spent on operating them (including pay for their crews) is spent on running the 3 CVAs (including pay for their crews). It's either 3 strike carriers or 3 Invincibles not 3 strike carries and 3 escort cruisers or 3 Invincibles. There's not the money to pay for 6 ships and there's not the money to pay the crews of 6 ships.

CVA.02 is probably an evolution of CVA.01 incorporating the lessons learned from CVA.01 and CVA.03 is probably an evolution of CVA.02 incorporating the lessons learned from CVA.02.

NB I started writing this after uploading Message 53. Then a large chunk of real life happened, which prevented me from finishing it until much later and I didn't see Message 51 (which contradicts some of this) until this message was ready to post. But as the man said, I've started so I'll finish.

 

[CV12Hornet]

Something else I keep thinking is the big American ships of the period, the Tarawa class, were steam powered just as the USN was embraced GTs in a big way with Spruances and OHPerrys. Perhaps steam is simply better for such large ships in the 70s.

That's generally correct due to the power limitations of aeroderivative gas turbines that weren't really overcome until post-Cold War, but with the Tarawas specifically I think it was just the lower maturity of USN marine gas turbines at the time. They were never quite able to lick the reliability issues of the FT4, their equivalent to the Marine Olympus, to their satisfaction. That plus general design conservatism.

 

[EwenS]

The RN actually had a strong latent tradition of this pre-CVF - the Maltas, the 1952 designs and arguably CVA-01's island was a semi-twin given that its lower mid-section was basically tunnels/vehicle hangarage.

But the reasons for the two islands were different in each case.

In the final Malta design, Design X1, the need for two islands were driven by the need to incorporate an expansion joint in the flight deck at the point of division. It was an open hangar, unarmoured design, akin to US carriers where the strength deck was the hangar deck and everything above superstructure. All the boiler uptakes from both fore and after boiler rooms were combined into a single funnel on the larger forward island. The need for a second island was being driven by the need to accommodate all the radar aerials and gun directors being planned for the ship.

In the two island 1952 designs, the flight deck was the strength deck, and each set of boilers was given its own separate funnel, one in each island structure. CVA-01 again used two sets of funnel uptakes. That is a similar layout to that chosen for the QE class today.

 

[Rule of cool]

I don't know enough about exhaust heat-exchangers to say whether they could generate sufficient steam. I don't think that the capacity of CVA-01's wet accumulators has been stated but US carriers of the time had 16,000gal capacity accumulators that held 8,000gal of boiler feed water or steam-generated feedwater in nuclear ships).
Nobody has ever built a GT-powered steam catapult carrier and probably never will now. It is certainly not ideal.

It's the same principle as a combined cycle gas power plant, and they're pretty common and simple, GTs make a lot of exhaust heat after all and generating the heat is the first problem when generating steam.

My question would be how to keep a head of steam up given that a GT ship turns it GTs on and off to save fuel, but I'm sure that's a pretty simple setup issue that an engineer could address.

 

[Rule of cool]

Well first the RAF has to have carrier capable aircraft (compare the RN Phantom FG.1 with the RAF Phantom FGR.2) and secondly the RAF pilots need additional training to allow them to land an aircraft on a carrier deck.

IIRC there were some issues back in the day with RAF pilots who didn't want to go to sea on Ark's squadrons. "If I wanted to go to sea I'd have joined the FAA" type attitudes.All that time away from family wasn't something they felt they had signed up for.

If the RN is keeping it's fleet carriers then the RAF doesn't need to stand up TASMO, those aircraft stay in (or be bought for) the RN. It's just juggling manpower caps between the services.

 

[Rule of cool]

I've just done a quick calculation, on the 1/4 structure, 1/4 propulsion and 1/2 everything else ship cost assumption, can someone tell me if I'm deluding myself. Other assumptions are 53,000t was as much as CVA01 be on 3 shafts/135,000shp and it was to cost 60m pounds (disputed, but easy for the maths).

Decreasing the ship to 48,000t would make the ship cost 58.5m pounds, that's ~10% off the 15m hull/structure cost.

Increasing the ship to 58,000t would make the ship cost 66.5m pounds, that's ~10% on to the 15m hull/structure cost and ~33% on to the 15m propulsion cost for the 4th steam machinery/shaft.

So steel is cheap, and air is free as long as other costs like propulsion remain fixed.

 

[Hood]

Just curious, how are you calculating the cost and what date is your £ Sterling figure pertaining too? The 1970s is a time of high inflation, have you accounted for that?

 

[NOMISYRRUC]

I imagine the premise to not include a continuous build of a class of carriers, the 1952 carrier will see to that. It would likely enter service in 1959-60 at the expense of the Victorious rebuild, Eagle would get her early 60s rebuild, CVA01 would be the replacement for Ark and this 1978 carrier would be the replacement for the Eagle by the early 80s. The RN wouldn't need another carrier until the early 90s to replace the 1952 carrier, leading to 5-year build gaps between big carriers that take 7 years to build.

From that I'm assuming that the 1952 Carrier built instead of rebuilding Victorious is laid down in 1950 and completed in 1958. If that's correct plans to modernise the Illustrious class have to be abandoned by 1948 to give the DNC time to design the new ship.

In that case there's a good chance that a second ship is built instead of completing Hermes. Then the early 1970s strike carrier fleet is CVA.01 and two 1952 Carriers. Then I think a pair of strike carriers would be built between the early 1970s and the middle 1980s (instead of the OTL Invincible class) to replace the 1952 carriers.

The backstory for that is:

• Hermes is cancelled soon after the end of the war, along with the Malta class, the 4 Centaurs that hadn't been laid down and the third Audacious.
• The 9-Year Plan of 1948.
  • 8 Fleet Carriers.
    • 6 new fleet carriers to be completed by 1957 instead of modernising all 6 Illustrious class.
    • Ark Royal and Eagle.
  • 3 or 4 Light Fleet Carriers
    • 3 Centaur class instead of 4.
    • One of the Colossus or Majestic class ships might take the place of Hermes.
• The Revised Restricted Fleet of 1949.
  • 6 Fleet Carriers
    • 3 new fleet carriers to be completed by 1957 instead of modernising 3 Illustrious class.
    • Illustrious given a limited modernisation so it can be the trials and training carrier.
    • Ark Royal and Eagle
  • 3 or 4 Light Fleet Carriers
    • 3 Centaur class instead of 4.
    • One of the Colossus or Majestic class ships might take the place of Hermes.
• The 1951 Rearmament Programme.
  • 6 Fleet Carriers
    • 3 new fleet carriers to be completed by 1957 instead of modernising 3 Illustrious class.
    • Illustrious given a limited modernisation so it can be the trials and training carrier.
    • Ark Royal and Eagle
  • 6 Light Fleet Carriers, plus 4 serving in second-line roles.
    • 3 Centaur class instead of 4.
      • All 3 ships to be fitted with steam catapults and angled flight decks.
    • Magnificent taking the place of Hermes.
      • She'd be transferred from the RCN to the RN when HMCS Bonaventure was completed.
    • 2 Colossus class plus 4 ships in second-line roles, e.g. Triumph as the cadet training ship.
• The 1954 Defence Review.
  • 4 Fleet Carriers.
    • 2 new fleet carriers being built instead of modernising Victorious and completing Hermes.
    • Ark Royal and Eagle.
  • 2 Light Fleet Carriers.
    • Centaur and Bulwark which would be fitted with steam catapults and angled flight decks.
    • The 1952 Carrier being built instead of Hermes would replace Albion, which in turn would replace one of the Colossus class ships serving in a second-line role.
    • Plus some of the Colossus class serving in second line roles. E.g. Ocean and Theseus, which replaced Implacable and Indefatigable in the Home Fleet Training Squadron.
• The 1957 Defence Review is.
  • 5 Strike Carriers - Ark Royal, Centaur, Eagle and the pair of 1952 Carriers.
  • 2 Commando Carriers - Albion and Bulwark.
• Then we come to the early 1960s.
  • I think the initial plan will still be for a new class of 5 ships to replace the 5 existing strike carriers between 1970 and 1980.
    • The 1952 Carriers are a massive improvement on Hermes and Victorious.
    • But both ships will still be over 20 years old in 1980 and therefore due for replacement.
  • Centaur would still be paid off at the end of 1965.
  • Eagle would still have her Standard A refit of 1959-64, but the cost and length of the refit mean that (as IOTL) the plan to have Ark Royal refitted to Standard A is cancelled.
  • P.1154 will still be cancelled in 1964 in favour of the Phantom.
    • There would be no plans to Phantomise Ark Royal and Eagle.
      • The RN already had 2 Phantom capable ships in the form of the 1952 Carriers.
      • Ark Royal and Eagle were due to be replaced by new Phantom-capable ships in the early 1970s.
      • The Phantomisation refits would be long and expensive.
        • (Before anyone replies, not necessarily for Eagle, but definitely for Ark Royal.)
      • They'd only operate Phantoms for a few years before the new ships replaced them.
      • Therefore, Phantomisation wasn't worth the time and cost.
    • There's no Hermes for the Phantom to operate from either.
      • As a result there were fewer differences between the British Phantom and the original.
      • That may include keeping the original J79 engines.
      • If that's the case the Phantom will enter service with the RN several years earlier than it did IOTL.
      • My guess is that the first operational squadron embarks on one of the 1952 Carriers in early 1967 instead of on Ark Royal early in 1970.
• The strike carriers aren't abolished under the 1966 Defence Review.
  • Dennis Healey allows CVA.01 to be built and she replaces Eagle in 1972.
  • In common with OTL, Ark Royal pays off in 1966.
    • IOTL she was Phantomised 1967-70.
    • ITTL she was used as a source of spare parts for Eagle.
  • Ark Royal and Eagle are scrapped from 1972.
  • The money spent on Ark Royal's Phantomisation is spent on a mid-life refit for the 1952 Carrier that was built instead of modernising Victorious.
  • The money spent on refitting Hermes 1964-66 and converging her to a commando carrier 1971-73 is spent on refits of the 1952 Carrier built instead of completing Hermes. The latter is equivalent to the 1967-70 refit of her sister ship.
• The commando carriers.
  • All other things being equal the commando carriers survive the 1964-68 defence cuts, but Albion isn't paid off in 1973, because there is no Hermes to be converted to a commando carrier 1971-73 and replace her.
  • They'll still be abolished under the Mason defence review of 1974-75.
  • However, unlike IOTL they won't be given a reprieve and be converted into ASW helicopter carriers.
  • Therefore Bulwark is still paid off in 1976, but isn't recommissioned in 1979.
  • And Albion be paid off in 1976 too. IOTL Hermes was converted into an ASW helicopter carrier and had another refit 1980-81 that enabled her to operate Sea Harriers.

 

[Rule of cool]

Just curious, how are you calculating the cost and what date is your £ Sterling figure pertaining too? The 1970s is a time of high inflation, have you accounted for that?

Those are the 1963-64 estimates for CVA01, used because they're neat and easy for a 'steel is cheap' thought exercise calculation.

A similar calculation would need to be made for this late 70s carrier. It's ok to play with displacement until it means going from 3 to 4 shafts and a couple of million quid worth of extra steel becomes an extra set of propulsion machinery which isn't cheap.

 

[Siberia]

Nuclear [propulsion]. Not beyond the realms of technical possibility, but I'm not sure a pair of PWR1 would be up to it. Plus we're talking massive costs and how to build it? Barrow building those sections of hull and shipping them to Scotland? Plus it probably means sacrificing a couple of SSNs in the building programme. It seems a step too far.

There's also the issue of refuelling. The US Navy has enough nuclear carriers that it can refuel and overhaul them on a rolling basis to take full advantage of the lifespan of the ship and spread its building costs. With the Royal Navy taking a carrier out of service for four or five years is going to create a large hole in the fleet.

 

[CV12Hornet]

From that I'm assuming that the 1952 Carrier built instead of rebuilding Victorious is laid down in 1950 and completed in 1958. If that's correct plans to modernise the Illustrious class have to be abandoned by 1948 to give the DNC time to design the new ship.

In that case there's a good chance that a second ship is built instead of completing Hermes. Then the early 1970s strike carrier fleet is CVA.01 and two 1952 Carriers. Then I think a pair of strike carriers would be built between the early 1970s and the middle 1980s (instead of the OTL Invincible class) to replace the 1952 carriers.

Building the 1952 carrier would have required sacrificing Victorious, Hermes, and the Tigers. So no second ship, not least because by the time one is considered the force structure means there's no need for another one but a need for a lighter carrier to replace the Centaurs.

Construction schedule was to lay down the ship May 1 1954, and complete the ship December 31 1958. However, there was no slip large enough available until January 1955, so practically speaking there would be a seven-month delay, which along with cancellation of the ships above should free up enough time and design resources to get the design ready to go by then.

I don't think your overall schedule is financially or temporally realistic; the British didn't think they'd have the money to buy new carriers until 1954 and it would be extremely difficult, even starting in the 1940s, to get so many ships ready by the Year of Maximum Danger in 1957. Not least because starting the design process in 1948 means it's going to severely drag out as new aviation technologies are developed.

 

[H_K]

Assuming the RN bought the Buccaneer and some sort of Phantom in the 60s what would a late 70s British fleet carrier, a follow-on from the CVA01 look like? How big would/could it be? What short of engines and how many shafts would it have? Would it have bigger cats than the CVA01s BS6s, and how many would it have? How big could/would the CAG be?

To take this topic in a slightly different direction. What if this late 70s carrier wasn't a follow-on to CVA01, but a new, budget-constrained carrier to replace Ark Royal circa 1979-80?

This carrier would operate either as a complement to the Invincible helicopter carrying cruisers (whose numbers would have been cut to only 1 or 2 hulls), or lead to Invincible's cancellation circa 1975. Also Sea Harrier likely wouldn't have moved forward (ordered 1975), though a greater emphasis on operating RAF Harrier GR 3s might have partially offset this.

So given budget constraints, no Sea Harrier, and the need to operate the existing crop of Phantoms and Buccanneers, how do you take cost out of CVA-01? Or start from scratch? e.g. No Sea Dart, lower top speed to reduce propulsion size? Keeping in mind that around the same timeframe (1975), the USN was studying ~33,000t VSS designs with 2 C13 catapults, a 100,000shp steam plant giving ~26.5 knots (sustained), and over 30 aircraft, costing roughly 1/3rd of a CVN.

 

[Rule of cool]

What about escorts? The 52 carrier and Eagle would be escorted by the County class in the 60s and 70s and the CVA01 by the Bristol and at least 1 more Type 82 to provide Task Group command facilities within the Task Force . The 1978 carrier will also need a pair of escorts with command facilities, one for AAW and one for ASW Task Group command, and at least 2 Counties will need to be replaced with command ships in a similar time frame for the 52 carrier's Task Force command escort requirement.

Perhaps the Batch 3 Type 42 and Batch 2 Type 22 would be DLGs with command facilities incorporated into their hull stretches.

 

[Rule of cool]

Building the 1952 carrier would have required sacrificing Victorious, Hermes, and the Tigers. So no second ship, not least because by the time one is considered the force structure means there's no need for another one but a need for a lighter carrier to replace the Centaurs.

That makes the 52-carrier sound like a panacea for the RNs ills in the 50s and 60s.

No expensive and slow double rebuild of the small and time limited Vic.

No 3 cruisers which became political millstones around the RNs neck by the early 60s.

No Hermes which also became a millstone around the RNs neck with regards to the Phantom or any post Sea Vixen fighter.

Construction schedule was to lay down the ship May 1 1954, and complete the ship December 31 1958. However, there was no slip large enough available until January 1955, so practically speaking there would be a seven-month delay, which along with cancellation of the ships above should free up enough time and design resources to get the design ready to go by then.

While I'm calling this the 52 carrier, I thought it was to be laid down in 1954 or so, so that timeline fits to the extent I've given it thought.

While official defence policy/strategy from 1949-57 was to have 6 carrier to refight WW2 with some nukes thrown in the RN was moving away from this before the RAF and Army. The Global Strategy Paper was written in 1953 I think, and the RN started moving toward it's official post 57 DWP position of 4 carrier before the 57 DWP which is why it got off lightly in the DWP. This move might provide the impetus for the cancellations needed to free resources up for the 52 carrier.

 

[Rule of cool]

To take this topic in a slightly different direction. What if this late 70s carrier wasn't a follow-on to CVA01, but a new, budget-constrained carrier to replace Ark Royal circa 1979-80?

This carrier would operate either as a complement to the Invincible helicopter carrying cruisers (whose numbers would have been cut to only 1 or 2 hulls), or lead to Invincible's cancellation circa 1975. Also Sea Harrier likely wouldn't have moved forward (ordered 1975), though a greater emphasis on operating RAF Harrier GR 3s might have partially offset this.

So given budget constraints, no Sea Harrier, and the need to operate the existing crop of Phantoms and Buccanneers, how do you take cost out of CVA-01? Or start from scratch? e.g. No Sea Dart, lower top speed to reduce propulsion size? Keeping in mind that around the same timeframe (1975), the USN was studying ~33,000t VSS designs with 2 C13 catapults, a 100,000shp steam plant giving ~26.5 knots (sustained), and over 30 aircraft, costing roughly 1/3rd of a CVN.

To the extent that money was a problem for the RN that led to the scrapping for the fleet carrier capability, it most certainly wasn't the biggest problem, the issue was one of budget rather than unit cost. CVA01 was cancelled because the RN needed 2 of them in the next decade and a 3rd immediately after that, which tied up a lot of the RN's acquisition budget for the next few terms of government in carriers that said government will never get the credit for.

By building the 52 carrier from 1954-55 by the mid 60s the RN only needs 1 carrier, which is entirely within the scope of a government elected in late 1964 to get the credit for and doesn't distort the budget for a decade and a half.

As for reducing unit cost, the ship needs to go 28kt+ to provide Wind Over Deck for launch-recovery in low wind conditions. While Sea Dart would likely not be fitted from 1978 Sea Wolf most certainly would be and that is costly. In any case the stagflation of the 70s throws any cost estimates out the window, just compare the Ark Royal's cost compared to the Invincible and Illustrious as an example.

 

[zen]

Type 43 was the project of the times alongside Sea Dart mkII a.k.a GWS.31.

 

[CV12Hornet]

What about escorts? The 52 carrier and Eagle would be escorted by the County class in the 60s and 70s and the CVA01 by the Bristol and at least 1 more Type 82 to provide Task Group command facilities within the Task Force . The 1978 carrier will also need a pair of escorts with command facilities, one for AAW and one for ASW Task Group command, and at least 2 Counties will need to be replaced with command ships in a similar time frame for the 52 carrier's Task Force command escort requirement.

Perhaps the Batch 3 Type 42 and Batch 2 Type 22 would be DLGs with command facilities incorporated into their hull stretches.

The RN estimates for AAW escorts was that they needed four missile systems per carrier, and the reason CVA-01 carried Sea Dart one is to cut down on the number of escorts. However, the 1952 carrier will not carry an area SAM system, and I don't think CVA-02 will either both to cut costs and to expand the flight deck area. So in practice I expect the RN will need 12 AAW escorts solely for carrier escort. Additional escorts were needed for escorting the amphibious force (4) and for picket duty (5 per 2 carriers, so call it 7 in a three-carrier force). Maximally you're looking at 23 AAW escorts.

Practically there's no way this is affordable, and they don't need so many amphibious and picket escorts - the latter can be replaced if the Brits actually buy a proper AEW platform. 14 I would say is the absolute minimum needed. Assuming your assumptions about command facilities holds water, at least 8 would need to be Type 82s.

This actually aligns with what I've been thinking about for my own timeline, so a force goal of 8 Type 82s and 6 Type 42s, with the stretch from the start, would make sense and be reasonably affordable.

That makes the 52-carrier sound like a panacea for the RNs ills in the 50s and 60s.

No expensive and slow double rebuild of the small and time limited Vic.

No 3 cruisers which became political millstones around the RNs neck by the early 60s.

No Hermes which also became a millstone around the RNs neck with regards to the Phantom or any post Sea Vixen fighter.

It's not a complete panacea - losing Vic and Hermes creates a significant force gap once the Centaurs are moved out of the strike carrier job - Eagle's rebuild means they'd still have to modernize Centaur and still they'd fall to three carriers once Albion is converted to a commando carrier unless a follow-on can be acquired.

 

[Rule of cool]

Type 43 was the project of the times alongside Sea Dart mkII a.k.a GWS.31.

IIUC the Type 43 was big to get more Sea Darts on board, presumably something would need to be sacrificed to create space for command facilities.

I don't like the amidships helicopter pad. I understand that is the position that pitches the least, but it just seems to have too many obstructions. The Spruance/Kidd/Tico method of moving the helicopter pad forward a bit from the very end of the stern seems much better to me as a way of reducing the pitching while giving a large, unobstructed approach from 180 degrees astern.

 

[zen]

Arguably the cheaper Type 44 based on Type 22 might resolve this.
But at the heart of things, even if you fund Sea Dart with VLS, you need a different set of shipside elements to make it justified.
That takes us back the thorny business of 3D radar....

However....if Type 82 is built with Broomstick and CVA-01 gets it as well. That's at least 9 sets and shifts the dial on later decisions.
Type 42 might then mount this as well.
But.....Type 909 as we know it is the result of the choice to bypass ASWRE's views for European politics and hopefully sell Sea Dart to the Dutch. Type 909 aa we know it is itself a limiting factor. In terms of cost, weight and placement.

So tracing back had ASWRE been listened to and funded. Their system precludes the Broomstick effects and makes such distribution of 3D sets alongside a lighter TIR system achievable.

 

[Rule of cool]

The RN estimates for AAW escorts was that they needed four missile systems per carrier, and the reason CVA-01 carried Sea Dart one is to cut down on the number of escorts. However, the 1952 carrier will not carry an area SAM system, and I don't think CVA-02 will either both to cut costs and to expand the flight deck area. So in practice I expect the RN will need 12 AAW escorts solely for carrier escort. Additional escorts were needed for escorting the amphibious force (4) and for picket duty (5 per 2 carriers, so call it 7 in a three-carrier force). Maximally you're looking at 23 AAW escorts.

Practically there's no way this is affordable, and they don't need so many amphibious and picket escorts - the latter can be replaced if the Brits actually buy a proper AEW platform. 14 I would say is the absolute minimum needed. Assuming your assumptions about command facilities holds water, at least 8 would need to be Type 82s.

This actually aligns with what I've been thinking about for my own timeline, so a force goal of 8 Type 82s and 6 Type 42s, with the stretch from the start, would make sense and be reasonably affordable.

It was one of the most interesting things when I read Hobbs' book on RN strike carriers. IIRC the idea was for a TAU of 2 carriers, each with 2 T82s as direct escort and 'spares' as a picket, an ASW hunt command ship, and 1 each to escort the Supply ships and Amphibious ships, for a total of 8. Defending the Amphibious and Supply ships with Couties got that number down to 6, but even with Sea Dart on carriers spare T82s were needed to command sub hunts and defence against air attacks. Personally I think 2 DLGs per BG should be enough given the carriers' own command facilities, and I agree about acquiring a proper AEW platform to remove the picket requirement.

It's not a complete panacea - losing Vic and Hermes creates a significant force gap once the Centaurs are moved out of the strike carrier job - Eagle's rebuild means they'd still have to modernize Centaur and still they'd fall to three carriers once Albion is converted to a commando carrier unless a follow-on can be acquired.

Nothing ever is a complete panacea, but it appears as if it would force the British Government and RN down a better road in the long run.

 

[Rule of cool]

Arguably the cheaper Type 44 based on Type 22 might resolve this.
But at the heart of things, even if you fund Sea Dart with VLS, you need a different set of shipside elements to make it justified.
That takes us back the thorny business of 3D radar....

However....if Type 82 is built with Broomstick and CVA-01 gets it as well. That's at least 9 sets and shifts the dial on later decisions.
Type 42 might then mount this as well.
But.....Type 909 as we know it is the result of the choice to bypass ASWRE's views for European politics and hopefully sell Sea Dart to the Dutch. Type 909 aa we know it is itself a limiting factor. In terms of cost, weight and placement.

So tracing back had ASWRE been listened to and funded. Their system precludes the Broomstick effects and makes such distribution of 3D sets alongside a lighter TIR system achievable.

It appears as if the Counties had Flag officers' spaces and space for an Admiral's Barge designed in while the Bristol's design didn't specifically have an Admirals Barge it did carry one when needed and did have an Admiral's cabin as well as staff space designed in. I suspect that by the 70s a DLG would be designed around a Commodore, with staff command spaces but not the rigmarole of an Admiral with the formal cabin and barge.

As for radars, the Type 988 is the path of least resistance and in my mind a good piece of kit, so I have no objection to its widespread adoption.

 

[zen]

It's an interesting question what happens if there be 9 Type 988 and the Dutch ships also mount this.
That's a radically different outcome and with unknown consequences.
Once a production line is building Type 988s it gets progressively cheaper to order more and more affordable to run when you've already committed to 9 such sets.

So Type 42 might indeed gain this, trimming Type 82 jointery out, COSAG for COGAG, Ikara and the ASW mission and at the time even the 4.5" gun was in doubt.

It would help if there had been a single 3" L70 option or maybe opting for the Italian 76mm. Costs depending.

But others might be enticed into Type 988 as well possibly?

BTW some Type 43 studies do have the helicopter pad at the stern.