Could the UK have done a better job of maintaining carrier based air power?

[Archibald]

Nope it was too small, 18 000 tons. Although Harrier tested on Foch and Jeanne d'Arc in 1971-73. Could have been procured in place of Super Etendard.
As for PA58 to PH75 interlude (1959- 1974) - nothing (AFAIK). Foch and Clem were "fresh" and the Force de Frappe sucked all the military budget. The 1960's was a decade of sacrifice for conventional forces, although a booming economy really helped. Then the first shock oil shock screwed the economy, luckily enough by this point the FdF was largely in service. Tactical nukes were a touch less expensive - AN-52, Pluton.
The FdF cost half the cost of Apollo ($10 billion dollars) but France was no USA superpower...

 

[NOMISYRRUC]

If the UK had been able to build a gas turbine powered CVV for the 80s would France have followed suit or would it still have gone nuclear?

I don't see why the UK couldn't have built a gas turbine powered CVV in the 1980s because it did build 3 gas turbine powered CVL in the 1980s. The Invincible class had four Olympus GTs driving 2 shafts and the ship I've proposed has six Olympus driving 3 shafts.

Edit:

Do you mean was it technically possible? Which it is.

Or whether it was politically and financially possible? Both of which are debatable, but I've done all the debating that I want to on those subjects.

 

[zen]

It's quite reasonable to consider nuclear power for the period and by the 70's the UK had a sizable staff of nuclear engineers with a decent body of knowledge of working reactors.
So it's not beyond possibility for an Anglo-French nuclear plant program. France sent quite a few people over to the UK to expand it's own staff. All civil to my knowledge.

As to GT power....
Olympus TM3
28,000 shp (21,000 kW) nominal.
So two per shaft is 56,000shp maximum.
Giving 112,000shp
Which is 1,000shp more than Victorious's 111,000shp.
Consequently three shafts is 168,000shp.
150,000shp was enough for the Audaciouses.....

So certainly in theory it's possible to design and produce an CATOBAR CV with such GT power.

 

[uk 75]

My ignorance. The real world is awash with gas turbine powered conventional aircraft carriers. I have read widely in books on the RN and British industry and have never seen a design quoted anywhere for such a ship.

In my defence if it is easy as you say why is the RN saddled with two giant helicopter carriers which can only be converted to CTOL with the highly successful electric catapults from the Ford?

 

[Scott Kenny]

We'd probably have a new UK designation for ship reactors.
LPWR perhaps (L for Large).

A planned CVN might be a 60's phenomenon, and would be part of a larger nuclear fleet concept. The likelihood is for DDGN as well.

Nah, knowing how the UK does things it'd be a PWR1* Mk2... Or something similarly absurd.

Not sure about pwr1.
Nimitz: 1100mw thermal/210 shaft power
Cdg: 300/60

CVA-01 would have had ~100 mw, the US CVV ~75mw shaft power if I read that correctly. So the requirement is ~375-500mw thermal.

The nr for s5w around is 78 mw thermal, If pwr1 is a bit stronger it might just suffice for the lower end. But more likely maybe 6, but that would be an unusual arrangement?

I am not willing to assume much improvement over S5W, not more than probably 85MW (~10% improvement).

As to why Enterprise had 8 reactors, they figured that each reactor was one boiler, and previous US carriers had all had 8 boilers. Which gets into way too much maintenance. You want bigger reactors so you can have basically one reactor per shaft, even if the steam header is all cross-connected.

My ignorance. The real world is awash with gas turbine powered conventional aircraft carriers. I have read widely in books on the RN and British industry and have never seen a design quoted anywhere for such a ship.

In my defence if it is easy as you say why is the RN saddled with two giant helicopter carriers which can only be converted to CTOL with the highly successful electric catapults from the Ford?

Because the idiots doing the planning didn't order them as CATOBAR ships in the first place!

 

[uk 75]

A very detailed look at the cats and traps saga of the QE/PoW

Cats, traps and claptrap. Why the Royal Navy’s new aircraft carriers operate VSTOL aircraft | Navy Lookout

www.navylookout.com

This is relevant to the discussion about earlier carrier options for the UK.

Fitting steam catapults to a conventional carrier was expensive and the VSTOL aspect was cheaper so made the project possible.

The difference in the alt 70s was that Sea Harrier still less F35B would not be available.

Faced with designing and building a carrier able to operate a Phantom and Buccaneer airgroup with Hawkeye AEW/COD in 1970s Britain I am not sure that a decent design existed or that three rather than two ships was feasible.

The real world Invincible class proved hard to get into service. Invincible (Unfinishable as she became known) took a decade to order and build. All three were not in service till the mid 80s. Propulsion and other problems plagued what were much simpler ships than a GT CV1.

Experience from Ark Royal in the 70s onward showed that the RN finds it hard to crew more than one in service big ship at a time.

 

[NOMISYRRUC]

The real world Invincible class proved hard to get into service. Invincible (Unfinishable as she became known) took a decade to order and build. All three were not in service till the mid 80s.

At least Barrow completed Invincible. The Type 42 destroyer Cardiff had to be completed by Swan Hunter at the former Hawthorn-Leslie yard.

Extended building times were par for the course in the 1970s. The first 3 Nimitz class took longer than planed to build, i.e. about 7 years each instead of about 4 years each. (For comparison Enterprise took 3½ years to build.) The California, Spruance & Virginia classes and the first Ohio class SSBNs were delivered late.

Originally all 3 ships were to have been built by Vickers at Barrow. Hobbs wrote that the Labour Government that came to power in 1974 decided that the second & third ships should be built at Barrow for political reasons and that this added £50 million to the cost over the production phase of the project. However, I've read elsewhere that the Illustrious & Ark Royal were built by Swan Hunter because Barrow was overloaded with work, i.e. nuclear submarines, Invincible and an eventual total of 4 Type 42 destroyers including the one built for Argentina.

It might have helped if all 3 Invincibles or all 3 ALT-CVA.01s had been built by Swan Hunter.

Propulsion and other problems plagued what were much simpler ships than a GT CVA.01.

A GT CVA.01 would have been much bigger (and more heavily built) than the Invincible but I disagree that it would have been more complex. The GT CVA.01 would have had the same equipment as Invincible plus the steam catapults & arrester gear. I explained this in detail in the post where I estimated the extra cost of building 3 GT CVA.01s in place of the 3 Invincibles.

Experience from Ark Royal in the 70s onward showed that the RN finds it hard to crew more than one in service big ship at a time.

Is that due to being unable to recruit & retain enough sailors to maintain the RN at it's Vote A strength or because the Government & Treasury wouldn't/couldn't pay the extra sailors wages? If it's the latter the cost of paying more people wearing dark blue uniforms is offset by paying less people wearing light blue uniforms.

 

[orlovsky]

I am not willing to assume much improvement over S5W, not more than probably 85MW (~10% improvement).

So 4 pwr1 might be a just workable minimum.
With the PANG design, two K15=300 mw thermal would supposedly work up to 60k t and 27 kts top speed. CdG has a bottleneck in the propulsion system, but it's not clear to me what the problem actually is.

 

[Yellow Palace]

My ignorance. The real world is awash with gas turbine powered conventional aircraft carriers. I have read widely in books on the RN and British industry and have never seen a design quoted anywhere for such a ship.

It's never been done because nobody's ever needed it done.It just so happens that every aircraft carrier ever built that's needed catapults has either had an oil-fired steam plant, or a neutron-fired steam plant, so steam was readily at hand.

If the UK had wanted to fit steam catapults to QEC, or to a hypothetical gas turbine carrier in the 1970s, it could and would have been done. It wouldn't be off-the-shelf, but it wouldn't require inventing new technology either. Generating steam is something that industrialised countries have been doing for several centuries.

That it wasn't done isn't because it's infeasible, but because it wasn't considered desirable. That's partly because of timing, and partly for political reasons discussed ad infinitum elsewhere.

 

[Archibald]

However, I've read elsewhere that the Illustrious & Ark Royal were built by Swan Hunter because Barrow was overloaded with work, i.e. nuclear submarines, Invincible and an eventual total of 4 Type 42 destroyers including the one built for Argentina.

That irony...

 

[NOMISYRRUC]

It's quite reasonable to consider nuclear power for the period and by the 70's the UK had a sizable staff of nuclear engineers with a decent body of knowledge of working reactors.
So it's not beyond possibility for an Anglo-French nuclear plant program. France sent quite a few people over to the UK to expand it's own staff. All civil to my knowledge.

As to GT power....
Olympus TM3
28,000 shp (21,000 kW) nominal.
So two per shaft is 56,000shp maximum.
Giving 112,000shp
Which is 1,000shp more than Victorious's 111,000shp.
Consequently three shafts is 168,000shp.
150,000shp was enough for the Audaciouses.....

So certainly in theory it's possible to design and produce an CATOBAR CV with such GT power.

The Real-CVA.01 was to have had steam turbines producing 135,000shp and driving three shafts. My ALT-CVA.01 was to have had the Real-Invincibles machinery plus an extra pair of Olympus GTs driving a third shaft.

I've seen the TM3B Olympus GTs on Invincible quoted as being anywhere between 23,500shp and 28,000shp. Hobbs and my copy of Jane's 1986-87 provided the lowest figure. My copy of Jane's 1986-87 also says that the TM3B Olympus engines on Types 21, 22 & 42 produced 25,000shp.

However, as the Real-CVA.01 required 135,00shp the ALT-CVA01 could have had six TM3Bs de-rated to 22,500shp for a total of 135,000shp.

Hobbs attributed the vibration problems to the lightly built hulls which were cured by adding 500 tons of steel. My guess is that ALT-CVA.01 would have had fewer vibration problems or none at all due to having a larger hull that was more heavily built and less horse power on each shaft, i.e. 45,000 instead of between 47,000shp and 56,000shp.

For the benefit of people who prefer a two-shaft ship, could the Olympus be developed to produce more than 28,000shp? So we could have four Olympus producing up to 150,000shp driving two shafts. Or is having six Olympus GTs producing 150,000shp driving two shafts feasible? That is three GTs driving each shaft in the two-shaft version instead of two GTs driving each shaft in the 3-shaft version.

 

[uk 75]

Like the ex PM I am not too hot on Science so please bear with me.
I get that catapults on oil or nuclear powered carriers use steam from the main propulsion but in the case of gas turbines am I right in thinking the catapults would require a separate steam producing plant of some kind to power them?
Has any UK manufacturer devised such a system?

 

[NOMISYRRUC]

This is a link to the most recent alternativehistory.com thread on the ALT-CVA.01.

Callaghans follies (1970s new build fleet carriers)

I think that's the worst of both worlds. However, as nuclear power was @Dalriadan Archangel 21's suggestion, I'll leave it to him to provide the definitive answer. Not sure a GT and nuke would be that bad as long as the GTs would only be needed for high speed running? It would give almost...

www.alternatehistory.com

I'm posting it because turbo-electric drive was suggested for the gas turbines.

@I lurk therefore I am in Post 51 on Page 3 wrote the following.

Turbo electric allows far better compartmentalisation as it takes out the long propeller shaft runs, which are a major flooding risk, and you can split up machinery spaces more. It also allows the engines to be run at their most efficient speeds more often. The downside of turbo electric is greater weight of steel from all those extra compartments, but you are using much lighter gas turbines.

Which resulted in me asking the following in Post 86 on Page 5.

Can the gas turbines for a turbo-electric drive ship be higher in the ship than the gas turbines for a direct-drive ship? If it does that reduces the volume of the hull consumed by the air intakes and outtakes for the gas turbines.

To which he replied in Post 89 on Page 5.

If you are using the turbines to generate electricity, rather than being connected to gearboxes and propeller shafts, then they can be anywhere you want, as they are linked to the motors by cables. Big Lizzie and POW have a turbo generator directly under each Island.

And @sonofpegasus in Post 87 on Page 5 added.

In the mid 1970's Vosper Thorneycroft were promoting an 8000, tom light carrier to carry eight Harriers and two Seaking helicopters. It would be Gas turbine electric drive with nine GT's providing some 20Mw of power.
The design had five turbine at hanger deck level to starboard under the island and four more aft of the hanger.
so spreading the generators about within reason would seam practicable.

I thought the ALT-CVA.01 would have had a smaller hangar than the Real-CVA.01 due to the air intakes & outtakes for the gas turbines consuming more internal space than those for the boilers. However, Hobbs attributed the dumbbell shaped hangar on the Invincible to each Olympus GT having a lift to the flight deck. Fortunately, it looks like they'd be non-issues on a turbo-electric ship because it looks like the gas turbines can (within reason) be mounted anywhere on the ship.

Correction

Hobbs wrote that the narrow centre section of the hangar on Invincible was due to the gas turbines requiring intakes & exhausts of five times the cross-sectional area that would have been required for steam machinery and the individual lifts for the four gas turbines.

 

[uk 75]

The main flaw in the Callaghan's folly thread is that the Royal Navy after 1966 moves on from carriers to submarines.
With the withdrawal from East of Suez and stronger focus on NATO the RN uses its growing nuclear submarine force to work with the USN to meet the threat from the huge Soviet submarine fleet to the crucial North Atlantic links between USA/Canada and Europe.
No senior RN officers are lobbying for carriers if it reduces SSN numbers.
This is one of the reasons Nott is able to sell Invincible to Australia as Ark/Illustrious are sufficient for ASW work and rushing Royal Marines to Norway in a crisis.
Until Galtieri does a Putin and invades the Falklands carriers were the pet topic of a few Tory MPs.
Nott's Royal Navy focussed on SSNs comes to pass despite Thatcher's Victory in the SA. By 1990 the RN has 13 SSN and only one CVS in service at a time with a shrinking escort fleet.
Ironically it is the Gang of Scots (G Robertson and G Brown) who bring carriers back to the RN after the Yugoslav war.

 

[Yellow Palace]

Or is having six Olympus GTs producing 150,000shp driving two shafts feasible? That is three GTs driving each shaft in the two-shaft version instead of two GTs driving each shaft in the 3-shaft version.

Three GTs on each shaft shouldn't be prohibitive. I'd probably go for two gearboxes each side, giving a 1+(1+1) arrangement on each shaft, mimicking a COGAG setup - cruise on the singleton GT, then cut in the boost pair for maximum speed.

If you're doing electric drive, the architecture is in some ways simpler, though you may not want to put everything into a common busbar.

Has any UK manufacturer devised such a system?

Of course not. Nobody has stated a requirement for one. But it'd just be a steam boiler, which is far from a novel bit of engineering.

 

[Hood]

Biomass boiler using scrapings of food leftovers and used chip fat from the galley.

 

[uk 75]

The real world US Navy faced with a requirement to build a carrier for the 1980s looked at a steam boilered CVV or a rerun of the JFK. The closest thing to CVA 01 in the USN in terms of size were the Tarawa LHA or the Wasp LHD which used gas turbines and steam boilers.
Given that the steam powered Fearless and Intrepid served the RN long after the 80s I see no reason why an RN CV01 should not use a mix of gas and steam.

So how do we get these ships ordered in the 70s?. If the Soviet Navy had grown its surface fleet faster in the 60s and built planned carriers then a good case could be made in 1971 or so for building CV1 instead of Invincible.

 

[A Tentative Fleet Plan]

150,000shp between two shafts means 75,000shp per shaft. This is more than contemporary US CVAs and CVANs, and seems to go over limits on shp created by propeller cavitation.

I don't think there's any practical problem with dividing six Olympus' between three shafts, the main issue is the volume needed for the uptakes, 50% more than on the Invincible-class, that will mean quite a large island, with the attendant effects on flight-deck area.

Perhaps a better option would be smaller number of more powerful gas turbines, for example a marinised RB.207 to act as an LM2500, an FT-9 or even a MT30 equivalent?

COGAG-CVA could have an auxiliary boiler to provide steam for the catapults, alternatively it could have a sort of COGAS system (used on some cruise ships), with steam being generated for the Gas Turbines' exhausts, with the steam being used to feed the catapults to keep them running instead of a steam turbine.

 

[uk 75]

Biomass boiler using scrapings of food leftovers and used chip fat from the galley.

I always forget the ingenuity of the British.

 

[NOMISYRRUC]

I don't think there's any practical problem with dividing six Olympus' between three shafts, the main issue is the volume needed for the uptakes, 50% more than on the Invincible-class, that will mean quite a large island, with the attendant effects on flight-deck area.

I though of that too. However, its 50% more machinery in a hull that displaces 172% more. Also, using the upper end of the scale the four Olympus GTs on Invincible produced 112,000shp, but six on the ALT-CVA.01 only need to produce 135,000shp (as steam turbines on the real version only produced 135,000shp) which is an increase of 20%.

 

[Hood]

Marine Speys came in at around 18,000shp and quickly scaled up to around 26,000shp.
The Marine RB.211 would probably have been around 25,000-30,000shp so would have been an Olympus replacement, its better fuel economy would help range.
So four RB.211 might give you 120,000shp total, still leaves you a little short though of power for a fleet carrier.

You might loose a little more space to larger downtakes and uptakes too. This is the main drawback with having a gas turbine-powered carrier. Is not so much the drawback that you lose hangar space, but that the island ends up being massive and you lose deckspace. Look at Invincible, the island is massive with its twin funnels and downtakes which robs deck space. CVA-01's island block was about 195ft long, 22ft wide, Invincible's is a whopping 300ft long but both were about 22ft wide (not counting overhangs and platforms etc.). Even if you take out the Type 909 spaces etc. its around 245ft long. In contrast, Nimitz's island was about 90ft long (plus another 42 ft including the radar mast behind the island, so let's say a total of 125ft of unusable space) and on average about 26ft wide (again ignoring platforms and overhangs).

 

[A Tentative Fleet Plan]

I though of that too. However, its 50% more machinery in a hull that displaces 172% more.

The Invincible-class' island already appears to be longer CVA-01s (which is already relatively compact due to the use of macks, this option is not available for a COGAG ship), it's not about the displacement of the ship, but flight deck area and internal hull volume for uptakes, which are much greater for a ship with gas turbines.

 

[Scott Kenny]

So 4 pwr1 might be a just workable minimum.
With the PANG design, two K15=300 mw thermal would supposedly work up to 60k t and 27 kts top speed. CdG has a bottleneck in the propulsion system, but it's not clear to me what the problem actually is.

Depends on how much speed you're willing to lose during flight ops, steam catapults suck a LOT of steam out of the propulsion system.

Having 6x PWR1+s would be better from a steam production level, but worse for maintenance. You'd really want a nuclear plant to have 4x PWRs each making 1.5x the power of a PWR1+, or even better yet 2x really big reactors each making 3x the power of a PWR1+ to keep the maintenance levels down. After all, each reactor needs a basic set of pumps, and each steam loop needs a set of pumps. Only having 4x steam loops from 2x reactors keeps your pumps down to ~6x or 8x.

Like the ex PM I am not too hot on Science so please bear with me.
I get that catapults on oil or nuclear powered carriers use steam from the main propulsion but in the case of gas turbines am I right in thinking the catapults would require a separate steam producing plant of some kind to power them?
Has any UK manufacturer devised such a system?

It's a basic steam boiler, easy enough to run on the same fuel as the GTs. You could probably have it up much higher in the hull than down in the bilges like the reduction gears and shafts have to be, giving shorter runs to the steam accumulator(s). And/or you can use the GT exhaust as a preheater for the boilers, there's plenty of free heat to steal there.

 

[BlackBat242]

The closest thing to CVA 01 in the USN in terms of size were the Tarawa LHA or the Wasp LHD which used gas turbines and steam boilers.

Steam boilers feeding geared steam turbines (LHA 1-5 & LHD 1-7) then gas turbines geared to the shafts for 12 knots and above, with auxiliary diesels powering electric motors on the shafts below 12 knots (LHD-8 and LHA 6+).

None had both boilers feeding geared steam turbines and gas turbines.

 

[zen]

COSAG was the basis of the County Class and the Type 82. So it's not impossible.

Getting a CV project through the narrows of the 70's is likely dependent on what happens in the 60's and perceptions during the 70's.

PWR-1 did, I seem to recall, get to 20,000shp with core H. Arguably a scaled up system ought to get to whatever is desired.

Post 50's carrier during the very late 50's and early 60’s could be conceived as nuclear (such ideas were studied) and the then NIGS and Type 985 concepts would drive a need for such powerplants.

But they'd be focused on the conventional fleet described and the nuclear Submarine effort. So in institutional terms it's more likely to seriously evaluate CVNs in the late 60's. Which at least means the RN can look at the USN for experience with such.

Financial crisii are certain to push such daring Ministerial decisions off into the 70's, when it might recieve a brief filip after the Oil Shock.
This might force convergence with the French view.

Edited in further point:-
Assuming a 1957 Sandystorm as per history, but in which the new carrier fleet plan continues. The arguments for long range SAMs were raging and Director Arial Warfare stated missiles could not yet replace aircraft...even as such aircraft were being cancelled.

The loss of DLIDeck Launched Interception, only piled more demands on the Fighter for standing patrol on CAP. Even though it justified killing off F.177.

This resulted in piling on a 4 hour CAP mission onto the OR.346 which was essentially the Buccaneer's successor and otherwise comparable to TFX. With all that implies.

In this scenario the case for F.177 or purchase of some more reasonably capable fighter to succeed Scimitar and Sea Vixen is much stronger.
Arguably the F.177 buys time and space for either missiles or a future FAW aircraft.
Had such gone ahead, assuming IOC by the early 60’s. The Anti-ship Missile Crisis induced by Soviet display of such in I think 1963 only strengthens the case more for the AEW and look-down shoot-down radar efforts.

 

[A Tentative Fleet Plan]

COSAG was the basis of the County Class and the Type 82. So it's not impossible.

I was suggesting something derived from COGAS (distinct from COSAG), sans the steam turbines, using the steam generated from the waste heat of the gas turbines' exhaust to power the catapults.

 

[zen]

I was suggesting something derived from COGAS (distinct from COSAG), sans the steam turbines, using the steam generated from the waste heat of the gas turbines' exhaust to power the catapults.

Which is exactly what I and

NOMISYRRUC have suggested. ​

 

[zen]

In this scenario the case for F.177 or purchase of some more reasonably capable fighter to succeed Scimitar and Sea Vixen is much stronger.

Apologies for self quoting but based on the scenario presented a shift occurs if something like Sea Hunter exists.
Especially if we're talking a reheated engine for supersonic speeds. Keeping the system valid for longer.
This pulls the rug out of Scimitar for anything but interim nuclear delivery and would cause exploration of options for an alternative interim capability.
Furthermore it undermines the immediate F.53 Saro case but ironically strengthens the F.177 case since this has the volume/weight capacity for adding in auto interception capability via datalink. As well as in variant form radar guidance for SARH AAMs.

All of which pulls out of OR.346 the need for fighter elements.

Thus from the late 50's, the Buccaneer successor would be viewed as something like the A5 Vigilante.

Edited in additional:-
Sea Hunter is reheated form shifts the dial in successor powerplants, such RB.106, BS.30 Zeus or AS developments.
Such alter the future decisions on aircraft.
Furthermore Sea Hunter with AI.23 and Firestreak alter future decisions.

 

[NOMISYRRUC]

I think the UK doing a better job of maintaining carrier based air power is closely related to the UK doing a better job of managing its aerospace industry. The 1952 Aircraft Carriers aught to have been able to operate the twin-Medway version of the P.1121 because they were designed to operate aircraft of its size and weight.

Therefore, we need to employ what is scientifically known as jiggery pokery to have it or a fictional heavy fighter in the Phantom class developed in time to be built for the RAF instead of the Lightning and the RN instead of the Sea Vixen. As the RAF version is built instead of the Lightning a suitable starting point may be a different Specification F.23/49.

 

[NOMISYRRUC]

The Invincible-class' island already appears to be longer CVA-01s (which is already relatively compact due to the use of macks, this option is not available for a COGAG ship), it's not about the displacement of the ship, but flight deck area and internal hull volume for uptakes, which are much greater for a ship with gas turbines.

You may be missing my point, which is that the "ship impact" of gas turbine propulsion on a hull the size of CVA.01 may be less than it was on Invincible because its machinery produced up to one-and-a-half times more power in a hull with nearly three times more volume. Or put another way the uptakes would require one-and-a-half times more volume but they were in a hull that had nearly three times more volume.

Also, some reference books say the GTs on Invincible produced 112,000shp and most reference books say the steam turbines in the Real-CVA.01 were to produce 135,000shp which is 20% more. In which case ALT-CVA.01's uptakes would require one-point-two times more volume than Invincible's in a hull that had nearly three times more volume.

However, if you allowed for that, fair enough.

 

[NOMISYRRUC]

The Invincible-class' island already appears to be longer CVA-01s (which is already relatively compact due to the use of macks, this option is not available for a COGAG ship), it's not about the displacement of the ship, but flight deck area and internal hull volume for uptakes, which are much greater for a ship with gas turbines.

Furthermore, I'm thinking of giving the gas turbines turbo-electric rather than direct-drive because the former aught to require less internal hull volume and flight deck area for the uptakes than the latter.

My point of departure for the development of gas turbines with turbo-electric drive is the Hotham trials. She was a Lend-Lease destroyer-escort with turbo-electric drive that the RN kept after World War II. The plan was to replace one of her two steam turbines with an English Electric EL60 gas turbine in order that a direct comparison of the steam and gas turbines could be made. But the development of the EL60 was abandoned in 1952 after the shore trials showed that the plant was overweight and not flexible enough for operation. They weren't cancelled in my "Version of History" because a suitable aircraft gas turbine was used instead of the EL60.

 

[NOMISYRRUC]

Link to Post 388 about the Saro 177 and the Sea Hunter.

I think the British rocket-plus-jet fighter programme was a dead end and the resources spent on the Avro 720, the two Saro aircraft and their rocket engines would have given the British taxpayer a better return had they been used to make an earlier start on Blue Steel and Black Knight & Black Arrow.

There's no need for Sea Hunter if the 1952 Aircraft Carriers are built. However, in a scenario where they aren't built there's the opportunity for some synergy with the RAF, because it can be built instead of the Hunter FGA.9/FR.10 with the bonus of giving the UK a supersonic light fighter for the export market that will take some sales away from the Mirage III/5 and F-5.

 

[NOMISYRRUC]

These are Hobbs criticisms of the Invincible class based on the reading that I've done for recent posts.

1. It wasn't CVA.01.
2. It was nearly as expensive as CVA.01.
3. The displacement was less than 20,000 tons for political reasons. This resulted in a hull that was too small and lightly built. E.g. he claims that the vibration problems were a result of the lightly built hull.
4. It had Sea Dart, but so did CVA.01 and I don't recall him criticising the fitting of Sea Dart to her.
5. The Sea Dart launcher mounted in what proved to be the most inconvenient place for both missile arcs of fire and aircraft parking forward of the island.
6. It had sonar, but so did CVA.01and I don't recall him criticising the fitting of sonar to her. Plus (if I remember correctly) Eagle had a Type 184 fitted for self-defence in her 1959-64 refit and the RN wanted to fit sonar to every aircraft carrier.
7. An excessively large island set to starboard of the centreline, but unnecessarily far inboard from the starboard deck edge.
8. The lifts obstructed the Sea Harriers' runway.
9. The narrow flight deck prevented its aircraft from landing next to the superstructure and the ship had to turn into the wind for the Sea Harriers & helicopters to land.
10. A larger hull would have produced a much better ship at negligible extra cost.

 

[Hood]

Invincible's machinery spaces seem to have been about 135-140ft long and were roughly the full beam of the ship. The attached PDF gives some details of her machinery spaces in terms of the downtake and uptake arrangements.
As you can see, this did restrict the hangar width. It's also worth remembering that generally the downtakes must be ahead of the turbine and the uptakes aft of it, just as in an aircraft, so this dictates where the funnels must be and their space between each other.

CVA-01's three main machinery spaces were 56ft long and separated by two auxiliary machinery spaces 40ft long which gives an overall length of 240ft. The maximum width of these spaces was 80ft (having more anti-torpedo protection than Invincible, 19ft on either side). The design incorporated 'repair by replacement' with 16 trunks and wider passageways and clear areas in the hangar floors for removing items.

The advantage of Invincible's machinery spaces is that the gas turbines are smaller so the auxiliary generators etc. can be mounted beside them and thus is saves length.

So while the island might be 100ft longer, the engine spaces might be 100ft shorter and will probably be mounted further aft. So sacrificing flight deck space gains you more internal space lower in the ship. In theory therefore it might be possible to lengthen the hangar slightly to compensate for any narrower sections around the downtakes, if you can keep the longitudinal strength of the hull sufficiently stiff, by moving some accommodation/stores lower down in the ship

(An edit to my previous post on islands, CVA's island was 192 x 18ft at the base, so slightly smaller than I estimated, the steam uptakes being roughly 9 x 9 ft each.)

 

[zen]

Extrapolations from supersonic research. A dalliance to near theory, but still alternative history.

AWA.58 variant with twin engines .
60 degree swept wing with drooped leading edge slats and elevons.

BP.114 twin engines
Bristol 177 twin engines
EE. P.1 twin engines
Fairey scheme 2 (seat not prone) twin engines
Gloster would need to scale up to a twin it's P.285
Hawker also needs to scale up to a twin.

Of these AWA.58 was actually ordered alongside EE (two each) to Specification E.16/49 and OR.282

However this was the single engined option AWA had put more effort into and was preferred by Ministery.
A more far-sighted decision would be to order the twin.

Serials WD466 and WD472 assigned.
Cranked wing of 40 degrees on outer portion.
Meeting 27 September 1949 to choose which to cancel Fairey or AWA.
AWA was asked to develop medium sweep option. Cranked wing was a result.
Revised high wing of delta form at 48 degees sweep and much musing on low tailplane or canard options. Though high T tail was the result (RAE really didn't like the low tailplane option as EE also encountered and seems to be down to RAE's Handel Davies).
Scaled model powered by Adder.
Which in theory could have tested low tail positions as well....
16 May 1950 AWA informed it was cancelled in favour of Fairey's Delta.

Had twin engined option been selected poor performance estimate might have been different and would certainly be a better basis for development into a fighter.
This element does stray into near hypothetical but it's a reasonable extrapolation from the real.

The high mounted delta is actually quite attractive for weapons pylons and fusilage waisting for Area Ruling ought to narrow majoritively behind the main gear stowage.
Seperating the engine inlet into two around a reprofiled nose ought to accommodate a decent AI scanner.
Main gear is fusilage mounted and so narrow of track, but various aircraft managed.

We can assume an increase in fusilage width and weight translates to increase in span to at absolute least 30ft and area to 350sqft.

A military version might have to raise wing area further to above 450sqft and thus span of at least 38ft, probably 42ft.

Irony is Fairey efforts delayed due to superpriority for Gannet and that rather undermines the pessimistic view of AWA held by AR/ARD(Res) and RAE.
DMARD was contact involved in giving AWA the chance to revise a delta wing submission.

 

[BlackBat242]

Furthermore, I'm thinking of giving the gas turbines turbo-electric rather than direct-drive because the former aught to require less internal hull volume and flight deck area for the uptakes than the latter.

My point of departure for the development of gas turbines with turbo-electric drive is the Hotham trials. She was a Lend-Lease destroyer-escort with turbo-electric drive that the RN kept after World War II. The plan was to replace one of her two steam turbines with an English Electric EL60 gas turbine in order that a direct comparison of the steam and gas turbines could be made. But the development of the EL60 was abandoned in 1952 after the shore trials showed that the plant was overweight and not flexible enough for operation. They weren't cancelled in my "Version of History" because a suitable aircraft gas turbine was used instead of the EL60.

In other words, the Metrovick G.6.

Or to be more precise, hold off on the forced 1947 spin-off of Metropolitan-Vickers' aero engine business to Armstrong-Siddeley Motors.

MV had been working on an axial-jet aircraft engine (F.1 first run in April 1939 {a turboprop}, with a pure-jet F.2 version starting work in July 1940, then developed to a useful power with first flight on a Lancaster 29 June 1943 and flight of 2 F.2/1s in a Meteor on 13 November 1943. Work continued with improvements in reliability and thrust with the F.2/4 Beryl early 1944. Work then switched to the Sapphire until the Ministry of Supply ordered MV to cease work on aircraft engines in 1947, with the Sapphire being passed to ASM.


In 1943 MV had been granted a contract to begin development of a ship-propulsion GT, which led to the Gatric (based on the F.2), which produced 2,500 shp, and which was installed as a boost-propulsion system in M.G.B. 2009 in 1947. Continued development was slowed by the loss of the Sapphire design team, but by 1948 another order had been awarded for a more-powerful version for installation in 2 Bold class patrol vessels. The G.2 was a 4,500 shp engine, and shipboard testing began in 1951. Unfortunately, problems (some of which were fairly basic errors that the aero team would likely have have caught early on) slowed development of a production version.

MV continued work on a ship-drive version, resulting in the 7,500 shp G.6 (run in 1961 in Ashanti) which powered the County and Tribal classes for the RN and the San Giorgio and Alpino classes for Italy.


English Electric's venture with the E.L.60A starting in 1947 with first run in 1951, followed by a shipboard version (R.M.60, 5,400 shp) which was abandoned in 1955.

Both MV and EE had made their engines in a heavy frame and over-built components, and the RN's attention soon turned to adapting aero GTs for shipboard use (again, with MV keeping the Sapphire division this change could have been speeded up or the G series lightened significantly), and the heavy-frame marinized GTs were dropped.


Bristol-Siddeley (merger of ASM and Bristol) started work to adapt the Proteus aircraft shaft turbine to shipboard use in 1955, and by 1958 one was installed in Brave Swordsman, producing 4,250 shp.
BS then began work on a marinized Olympus producing 15,000 shp and up, which was installed in ships from 1966 on.

This document gives a synopsis of the development of maritime gas turbines, which I severely abridged for my text above.

https://apps.dtic.mil/sti/tr/pdf/ADA037686.pdf

However, it has one omission I feel compelled to mention. There is a statement therein which comments that while the USN was interested in the development of MGTs in the RN, it was not ready to start installing them in warships designed for them for a number of years after 1967.

What he neglects is the US Coast Guard's decision to jump right in, designing the Hamilton class of high-endurance cutters (the USCG's largest ships) for CODOG propulsion in the early 1960s.

The class was laid down from Jan. 1965 through April 1971, and commissioned into service from March 1967 through March 1972.

They had 2 × Fairbanks-Morse 38TD8-1/8-12 12-cylinder diesel engines generating 3,500 bhp each and 2 × Pratt & Whitney FT4A-6 gas turbines (derived from the J75 jet engine, and first run in 1964) producing 18,000 shp each for propulsion - and 2 × 550KW GM 8-645 diesel generators and 1 × 500KW Solar Model 101506-2001 gas generator for ship's power.

General Electric had also been working on maritime gas turbines, and in 1964 ran the LM1500 (13,300 shp, derived from the J79 jet engine). The LM2500 (based on the TF39, which was a turbofan development of the J79 jet engine) producing 25,000 shp ran in 1967.
Note that the modern LM2500 MGTs are derived from the CF6 turbofan, which was a development of the TF39.



Interestingly, The Federal Republic of Germany (West Germany) was also early in the game, with the Brown-Boveri maritime GT producing 13,000 shp by 1957.

Here is another interesting paper on the subject of MetroVick and gas turbines. It has an interesting title:

https://pure.manchester.ac.uk/ws/portalfiles/portal/54530197/FULL_TEXT.PDF

Jakob Whitfield
Metropolitan Vickers, the Gas Turbine, and the State: A Socio-Technical History, 1935-1960

 

[NOMISYRRUC]

The Real World version of the 1950s Aircraft Carrier plans.

• The 1951 Rearmament Programme was for 6 fleet carriers (Ark Royal, Eagle, Illustrious, Implacable, Indefatigable & Victorious) and 6 light fleet carriers (Albion, Bulwark, Centaur, Hermes, Vengeance & Warrior) plus 4 light fleet carriers (Glory, Ocean, Theseus & Triumph) serving in second-line roles.
• The Radical Defence Review of 1954 cut that to 3 fleet carriers (Ark Royal, Eagle & Victorious) and 3 light fleet carriers (Albion, Bulwark & Centaur) plus 4 Colossus class light fleet carriers serving in second line roles. Hermes would have replaced Bulwark on completion and my guess is that Bulwark would have in turn replaced one of the Colossus class ships in the second-line.
• The Sandys Defence Review of 1957 cut that to 5 strike carriers (Ark Royal, Centaur, Eagle, Hermes & Victorious), 2 commando carriers (Albion & Bulwark) and Triumph converted to a heavy repair ship. According to Friedman, the Admiralty wanted 6 strike carriers to ensure that 4 were available at all times instead of 3. He gave the example of 1959-60 when Ark Royal & Eagle were refitting and only 3 modern carriers (Centaur, Hermes & Victorious) were available. He also wrote that the conversion of Albion into a commando carrier was delayed to maintain the required number of strike carriers.

My version of the 1950s Aircraft Carrier plans.

• The 1951 Rearmament Programme would have still been for 6 fleet carries and 6 light fleet carriers plus 4 light fleet carriers in second-line roles, but the 6 fleet carriers would have been 1952 Aircraft Carriers and the 10 light fleet carriers serving in first and second-line roles were Colossus & Majestic class ships.
• The Radical Review of 1954 would have been for 6 fleet carriers (all 1952 Aircraft Carriers) with some light fleet carriers serving in second-line roles.
• The Sandys Defence Review of 1957 would retain the 6 strike carriers (to ensure the availability of 4 ships at all times), 2 or 3 commando carriers (converted Colossus or Majestic class) and Triumph would still become a heavy repair ship.

 

[NOMISYRRUC]

Link to Post 396 about British marine gas turbines.

For what it's worth I knew nearly all of that. Is the EE R.M.60 a typo for the RR R.M.60?

I've written timelines where Exmouth was completed with gas turbines for comparison with her steam powered sisters, the County class had all GT propulsion (i.e. 8 G.6 engines in COGAG) and a Super Type 81 GP frigate with 4 G.6s driving 2 shafts that was built instead of the Rothesay, Tribal & Leander classes.

The most important thing that's new to me is that the G.6 was the marine version of the Sapphire.

 

[zen]

If MV follow AS path (assumption staff are similar or same) then GT for larger ships is possible from P.173 like development of mass flow 314lb/sec at 48" diameter
Or P.159 for 330lb/sec

While Sapphire derivatives ought to match Avon figures upto 21,000shp.

Knock on effect of MV making Sapphire more capable earlier is potential to crush RR and if delivering reheat more comprehensively. Then various schemes possible in a more condictive time frame.

This would flow to supersonic bomber and fighter developments.
If P.151 type produced (started as scaled Sapphire), this could trump DH Gyron Junior for Buccaneer S.1

 

[BlackBat242]

For what it's worth I knew nearly all of that. Is the EE R.M.60 a typo for the RR R.M.60?

I've written timelines where Exmouth was completed with gas turbines for comparison with her steam powered sisters, the County class had all GT propulsion (i.e. 8 G.6 engines in COGAG) and a Super Type 81 GP frigate with 4 G.6s driving 2 shafts that was built instead of the Rothesay, Tribal & Leander classes.

The most important thing that's new to me is that the G.6 was the marine version of the Sapphire.

MV started with the F2 Beryl to develop its shipboard gas turbines.
The F.2 Beryl was also the starting point for F.9 Sapphire.

So it is best to say that they were both based on the F.2 Beryl, although there may have been a little input from the Sapphire team before the 1947 forced split.


As for EE and RR, Napier's engine division was bought by the English Electric group in 1942 - and the EE group was merged into the Rolls-Royce engine division in 1961.

So work done by EE before 1961 was separate from RR's work. The R.M.60 was the productionized version of the E.L.60.