1930s Air Ministry surprise sanity options

[Cryhavoc101]

View attachment 309347

I plumped for three pipes as there was a lot of trunking to port to reach the edge of the deck area. The scissor lifts on the centreline fore and aft of the hanger will probably need up rating for heavier aircraft. This is the only good use I can see for the orphan calibre heavy cruisers. At present their capacity is for a fully armed Stringbag with 18 aircraft aboard in 2 squadrons. They will be hunting raiders in the Atlantic Ocean. I have a big question mark over when such a refit could have been applied across the class from the OTL experiment taken further.

Regarding when? I would suggest that when the British learn of the Deutschland Class being laid down they conclude that such a ship has but one purpose and that is to out run a battleship and to outfight a Cruiser while commerce raiding.

This causes some vexation as it was felt that there was never enough cruisers in the RN to properly patrol the sea lanes against raiders and a single British Cruiser could not hope to match these new "Pocket Battleships" and this would further stretch the RNs resources and possibly demand Battlecruisers to patrol secondary theatres such as the Indian Ocean and Southern Atlantic / West Africa Coast.

So the idea is raised to refit the remaining 3 Hawkins class Crusiers as 'Commerce protection Carriers' with the idea that a single ship with a dozen plus, scouts/Torpedo bombers can cover a far greater area than a single Cruiser and that teh cost of the conversions would be far less than the cost of an additional Cruiser.

I seem to recall that Cavendish/Vindictive had been chopped and changed several times and may not have been suitable for such modification at this time.

So I would guess 1930-36 as the scope of the new German navy takes shape.

 

[Just Leo]

I'm far from an expert on the Battle of Britain, but I think that the improved time to height and service ceiling would help considerably by enabling them to intercept the enemy at greater altitudes. IIRC the Hurricane Mk I was about 30 mph slower than the Bf 109E. The Mk II is only 10 mph faster, but it does reduce the Hurricane's disadvantage in speed with the Bf 109E by one third.

Without context, the post-BoB Hurricane II would have been less inferior to the BoB Bf-109E in speed, climb and dive. In context, post-BoB contemporary Bf-109s addressed the difference, and increased it, as did contemporary Spitfires.

 

[NOMISYRRUC]

That's a great Drawing - best I've seen of a refitted Hawkins - well done and thanks for sharing (the 4 Hawkins Cruisers refitted as sub 10K Ton 'Commerce Protection Carriers' is a darling of mine that often gets murdered by the harsh killer that is hard cold reality - damn its eyes)

I would expect at least 3 converted of the 4 survivors prior to the 1930 LNT (I seem to recall that sub 10K Carriers did not count towards the limit?) in order to have 1 in the Indian Ocean and one in the Atlantic and one in 'ordinary'.

In 1939 - everything else being equal and in an attempt to 'keeping it real' they might have a mix of 'older' Aircraft type on board such as the Baffin and Shark given the vessels 'secondary role' with the Swordfish equipping the Fleet carrier strike squadrons (until production can allow for the older aircrafts replacement).

This is from a post that I'm in the middle of writing

On the subject the interwar requirement for trade protection carriers hovered between 4 and 6. In October 1935 the Naval Staff argued that at least 16 would be needed for a simultaneous war with Germany and Japan. As part of policy it was intended to equip a group of 4 Merchant Ship Carriers and a force of Armed Merchant Cruisers once the war had begun. Once the armoured carriers had been begun it was intended to use the ships they replaced for trade defence. A 14,500 ton light fleet carrier carrying 18 amphibians was originally in the 1936-37 New Construction Programme with a total requirement for 7, but an extra Illustrious class ship was built instead.

The source for that was from Air Power and The Royal Navy 1914-45 A Historical Survey, by Geoffrey Till. My addition is that the extra Illustrious (Formidable) replaced the 14,500 ton light fleet carrier in the 1936-37 NCP. A sensible change IMHO.

This quote is from the bottom of Page 416 of British Naval Policy Between The Wars by Stephen Roskill.

It is interesting to remark that the naval staff recorded that small carriers of 10,000 tons displacement were needed for "the protection of trade against air attack in narrow seas." But, said the staff, "this is a luxury we cannot afford." On this point the staff's reasoning seems to have gone badly astray. The use of small aircraft carriers, as well as shore-based aircraft, to provide anti-submarine air escorts for convoys had been strongly recommended since 1918, and by 1924 it should have been clear that shore-based rather than carrier-borne aircraft were the best means of defending shipping in "narrow seas." Thus the natural conclusion surely was that trade defence carriers were not "a luxury," and that the field of operations for them would be on the broad oceans. This misreading of the use of air power at sea is typical of the period when British naval thinking still revolved around the concept of the decisive gun action between battle fleets, when trade defence took a very second place in the counsels of the Admiralty, and when most British naval men failed to appreciate the fundamental changes in strategy and tactics the advent of air power had wrought.

The notes I made from that book on the Admiralty's 10-year modernisation programme of 1924 said there was a requirement for 3 ships of this type. However, when I skimmed through my photocopies of pages 410 to 433 I could not find that. Also the other authors I have read on the subject like Friedman said that the Admiralty wanted its trade protection carriers to find and destroy surface raiders in the open ocean, not to defend trade from air attack in the narrow seas.

So there is an official requirement for ships like converted Cavendish class cruisers. However, they were the best cruisers the Royal Navy had before the County class appeared, which might be why the OTL Royal Navy studied new ships of 10,000 tons rather than converting existing ships. Another reason why the it did that is because a purpose designed ship would use the available tonnage better so that it would be faster and carry more aircraft. It has to be done before 1930 or after 1936 because the First LNT included ships of less than 10,000 tons in the 135,000 ton quota, but after 1936 the ships are so old that new ships would be preferable given the limited life left in their hulls and machinery.

 

[NOMISYRRUC]

View attachment 309347

I plumped for three pipes as there was a lot of trunking to port to reach the edge of the deck area. The scissor lifts on the centreline fore and aft of the hanger will probably need up rating for heavier aircraft. This is the only good use I can see for the orphan calibre heavy cruisers. At present their capacity is for a fully armed Stringbag with 18 aircraft aboard in 2 squadrons. They will be hunting raiders in the Atlantic Ocean. I have a big question mark over when such a refit could have been applied across the class from the OTL experiment taken further.

How do you cram 18 Swordfish into one of these when the larger Hermes could only carry 12?

Vital statistics of Hermes and Improved Birmingham class from Lenton and College

Hermes: 548 (pp) 598 (oa) x 70.25 (over bulges) x 18.75 feet - 40,000 shp = 25 knots - Displacement 10,850 tons.

Vindictive: 565 (pp) 605 (oa) x 65 (over bulges) x 17.25 feet - 65,000 shp = 30.5 knots - Displacement 9,770 tons.

Vital statistics of Vindictive from Chesneau

Length: 565 (pp) 605 (oa), 100 forward flight deck and 215 feet aft flight deck

Beam: 65 (hull) 55 forward flight deck and 65 feet after flight deck

From the same source Hermes had a flight deck 600 feet long and 65 feet wide.

Chesneau says that Hermes was ordered in July 1917. With hindsight her designers should have doubled the installed horsepower to 80,000 shp to increase the maximum speed to over 30 knots. That would increase the displacement but it would also mean a longer and wider fight deck and hangar. With hindsight they should also have built a second Hermes instead of converting Vindictive.

 

[perfectgeneral]

How do you cram 18 Swordfish into one of these when the larger Hermes could only carry 12?

Vital statistics of Hermes and Improved Birmingham class from Lenton and College

Hermes: 548 (pp) 598 (oa) x 70.25 (over bulges) x 18.75 feet - 40,000 shp = 25 knots - Displacement 10,850 tons.

Vindictive: 565 (pp) 605 (oa) x 65 (over bulges) x 17.25 feet - 65,000 shp = 30.5 knots - Displacement 9,770 tons.

Vital statistics of Vindictive from Chesneau

Length: 565 (pp) 605 (oa), 100 forward flight deck and 215 feet aft flight deck

Beam: 65 (hull) 55 forward flight deck and 65 feet after flight deck

From the same source Hermes had a flight deck 600 feet long and 65 feet wide.

Chesneau says that Hermes was ordered in July 1917. With hindsight her designers should have doubled the installed horsepower to 80,000 shp to increase the maximum speed to over 30 knots. That would increase the displacement but it would also mean a longer and wider fight deck and hangar. With hindsight they should also have built a second Hermes instead of converting Vindictive.

So what can you do with the 7.5inch gun Heavy Cruisers? Could they be up gunned to 8inch singles?

I will concede that a single squadron of 12 is about the maximum capacity, even with my super wide 63ft hanger design, as it doesn't look like they would be (re)built anyway.

 

[Cryhavoc101]

This is from a post that I'm in the middle of writingThe source for that was from Air Power and The Royal Navy 1914-45 A Historical Survey, by Geoffrey Till. My addition is that the extra Illustrious (Formidable) replaced the 14,500 ton light fleet carrier in the 1936-37 NCP. A sensible change IMHO.

This quote is from the bottom of Page 416 of British Naval Policy Between The Wars by Stephen Roskill.The notes I made from that book on the Admiralty's 10-year modernisation programme of 1924 said there was a requirement for 3 ships of this type. However, when I skimmed through my photocopies of pages 410 to 433 I could not find that. Also the other authors I have read on the subject like Friedman said that the Admiralty wanted its trade protection carriers to find and destroy surface raiders in the open ocean, not to defend trade from air attack in the narrow seas.

So there is an official requirement for ships like converted Cavendish class cruisers. However, they were the best cruisers the Royal Navy had before the County class appeared, which might be why the OTL Royal Navy studied new ships of 10,000 tons rather than converting existing ships. Another reason why the it did that is because a purpose designed ship would use the available tonnage better so that it would be faster and carry more aircraft. It has to be done before 1930 or after 1936 because the First LNT included ships of less than 10,000 tons in the 135,000 ton quota, but after 1936 the ships are so old that new ships would be preferable given the limited life left in their hulls and machinery.

Not so sure about being so old etc or life left they were still relatively young and at least 2 of them had been deep refitted just before the 1st LNT

None were in commision before 1919 and being rebuilt as carriers would involve the super structure being stripped which would allow for the Machinery to be reconditioned

OTL

Hawkins had her Machinery refitted to Oil firing boilers in 1929

Frobisher had her machinary changed to Oil firing boilers as well in 1929

Effingham was in good enough condition in 1937 to be rebuilt as a light Cruiser and her Engines and weapons replaced.

All of them spent long periods of the 30s in Reserve or as training ships etc and the last of the Counties were commissioned by 1930 and the 2 Yorks by 31 (matching Britains allowance of 15 Heavy Cruisers) so it would make sense if it was going to happen to happen in those following years where the 3 'heavy Cruisers' where now surplus to requirement - so they are not going to be missed.

So ATL instead of refitting the Hawkins and Frobisher in 1929 they are both stripped down - Machinery modernised and then rebuilt as Carriers in 1931-33 with Effingham - in reserve from 1931 - 34 before going through the same process in 34-36 in time to allow periodic refits on the first 2 always allowing 2 to be in service.

As for Air group sizes - USS Langley was not that dissimilar in dimensions and carried 37 AC - Hermes also roughly the same dimensions carried up to 20

So given that these ships are build 'rebuilt' after a decade or more of carrier use I don't think that fitting 18 folding wing AC is impossible.

However I would imagine that if operating with a Cruiser hunting group that it would make sense for the ships to also act as maintenance ships for the Amphibians so might probably have fewer aircraft in practice.

 

[Glyndwr01]

More development of the Vickers K leading to a belt fed version? More work on the .5" Vickers D? This could have an impact on army procurement as well.

Vickers K a vehicle machine gun instead of beds, Vickers D replacing the water cooled .303 version as HMG.

Maybe with less precedent for "buying American" there's no licence build of the godawful Liberty and we have Napier Lion (Nuffield Lynx?) powered tanks

https://www.forgottenweapons.com/light-machine-guns/beardmore-farquhar-machine-gun/

Light weight 0.5" machine gun less than half the weight of the Browning M2

 

[marathag]

Did Rolls Royce's sale of a handful of Kestrel engines to Germany in the middle of the 1930s help the German aero engine industry just as much as the sale of some jet engines to the USSR after World War II helped the Soviet aero engine industry?

Nothing in the Kestrel, or ramp head Merlin, for that matter, was any better than the Daimler or Jumos.

 

[perfectgeneral]

That Beardmore-FQ 12.5mm x ? 81?

 

[Glyndwr01]

That Beardmore-FQ 12.5mm x ? 81?

Yes it was designed around the Vickers 12.5 x 81

 

[Just Leo]

But Billy Beardmore didn't have a good business manager. His company was aided through the '20s by Vickers, and was just about gone by the time of his death in 1936.

 

[steamboy]

RE the Vindictives. I'd not convert them, too small, too fragile, keep them as they were with their single 7.5's and save money from converting them that way.

 

[Some Bloke]

https://www.forgottenweapons.com/light-machine-guns/beardmore-farquhar-machine-gun/

Light weight 0.5" machine gun less than half the weight of the Browning M2

Also less than half the rate of fire if memory serves.

 

[tomo pauk]

Nothing in the Kestrel, or ramp head Merlin, for that matter, was any better than the Daimler or Jumos.

Timing was much, much better 'in' the Kestrel than it was 'in' the Daimler or Jumos. Merlin, as-is, have had several advantages over these German engines, including the timing.

 

[NOMISYRRUC]

So what can you do with the 7.5inch gun Heavy Cruisers? Could they be up gunned to 8inch singles?

I will concede that a single squadron of 12 is about the maximum capacity, even with my super wide 63ft hanger design, as it doesn't look like they would be (re)built anyway.

Yes they could. IIRC that was studied IOTL and found to be practicable. I can't give you any details because I don't have Norman Friedman's books on British cruisers. I can't remember why it wasn't done, but it was probably the usual problems of cost, lack of dockyard space and new ships being more cost effective. Also the Japanese successfully rebuilt some of their heavy cruisers which were originally built with the armaments in single mounts with six 8-inch in three twin turrets.

Another problem with keeping them as 7.5" gun cruisers or upgrading them to 8" was the 1930 LNT. They either had to be scrapped by the end of 1936 because the heavy cruiser quota wasn't big enough for them and the fifteen 8" cruisers or be rearmed with 6" guns. However, the problem with that is that one Cavendish displaced twice as much as two C class cruisers and while the tonnage quotas were in force the Admiralty would have preferred 8 C class to 4 Cavendish class.

However, IOTL one of them was rearmed with seven 6-inch, but IIRC that was after the tonnage quotas expired.

OTOH having to scrap them under the LNT could be an incentive to covert four relatively new hulls to something else. But under the LNT aircraft carriers under 10,000 tons were now included in the tonnage quota. The four converted Cavendishes will absorb about 40,000 tons of that, getting a maximum of 72 aircraft to sea while Ark Royal displacing 22,000 tons could put 72 aircraft to sea. Therefore I think converting Cavendish class cruisers into aircraft carriers is not an economical use of the British Empire's tonnage quota as well as not being cost effective.

 

[NOMISYRRUC]

However I would imagine that if operating with a Cruiser hunting group that it would make sense for the ships to also act as maintenance ships for the Amphibians so might probably have fewer aircraft in practice.

It would make even better sense for them to operate a squadron of Swordfish to help the cruisers find the enemy warship and then put a few torpedoes into it so that the raider was sunk outright or slowed down sufficiently for the cruisers to catch and sink it. That was what the trade protection carriers the Admiralty wanted between the wars were intended to do.

 

[NOMISYRRUC]

As for Air group sizes - USS Langley was not that dissimilar in dimensions and carried 37 AC - Hermes also roughly the same dimensions carried up to 20

So given that these ships are build 'rebuilt' after a decade or more of carrier use I don't think that fitting 18 folding wing AC is impossible.

Unfortunately all the aircraft carriers that were converted from other ships carried less aircraft per ton of displacement than purpose designed ships.

Hermes and Vindictive were of similar dimensions, but because she was a purpose built aircraft carrier she would have carried more aircraft. Hermes carried as many as 21 aircraft early in her career, but by the time of World War II she was down to 12 Swordfish because it was a bigger aircraft. The same is going to happen with converted Cavendish class cruisers.

Langley is admittedly harder to explain because when I looked her up she was smaller than I thought. Some of the 37 aircraft can be put down to the American policy of having deck parks, which the British might not be able to automatically do because you need arrester gear and crash barriers to make the space for deck parks. I'm not sure that the RN was using them when Langley carried 37 aircraft. Also it could have been when they were using smaller aircraft. It could also be that as a converted collier rather than a converted cruiser that Langley had a fuller hull with a greater useable volume than a Cavendish. Finally Langley only had 7,000 shp for a speed of 14 knots. Hermes had 40,000 shp for 25 knots and Vindictive 60,000 shp for 29.5 knots. Therefore less space for machinery might have made more space for aircraft.

 

[NOMISYRRUC]

Not so sure about being so old etc or life left they were still relatively young and at least 2 of them had been deep refitted just before the 1st LNT

None were in commission before 1919 and being rebuilt as carriers would involve the super structure being stripped which would allow for the Machinery to be reconditioned

OTL

Hawkins had her Machinery refitted to Oil firing boilers in 1929

Frobisher had her machinery changed to Oil firing boilers as well in 1929

Effingham was in good enough condition in 1937 to be rebuilt as a light Cruiser and her Engines and weapons replaced.

All of them spent long periods of the 30s in Reserve or as training ships etc and the last of the Counties were commissioned by 1930 and the 2 Yorks by 31 (matching Britains allowance of 15 Heavy Cruisers) so it would make sense if it was going to happen to happen in those following years where the 3 'heavy Cruisers' where now surplus to requirement - so they are not going to be missed.

So ATL instead of refitting the Hawkins and Frobisher in 1929 they are both stripped down - Machinery modernised and then rebuilt as Carriers in 1931-33 with Effingham - in reserve from 1931 - 34 before going through the same process in 34-36 in time to allow periodic refits on the first 2 always allowing 2 to be in service.

The problem here is when the conversion was done. The older the ship the less the remaining life of the hull and machinery making the construction of a new ship increasingly more attractive. Also the more elaborate the conversion the more expensive it is which reduces the amount of money saved when compared to building a new ship.

Having written all that I would love to see 4 trade protection carriers acquired between the wars. Converting the Cavendish class is not my preferred solution, but it would do. The problem is the WNT and even more the 1930 LNT limiting the number of ships and I want the six 22,500 ton fleet carriers even more.

 

[Cryhavoc101]

The problem here is when the conversion was done. The older the ship the less the remaining life of the hull and machinery making the construction of a new ship increasingly more attractive. Also the more elaborate the conversion the more expensive it is which reduces the amount of money saved when compared to building a new ship.

Having written all that I would love to see 4 trade protection carriers acquired between the wars. Converting the Cavendish class is not my preferred solution, but it would do. The problem is the WNT and even more the 1930 LNT limiting the number of ships and I want the six 22,500 ton fleet carriers even more.

I don't disagree with anything you have said particularly where a purpose built Trade Protection carrier would make for a better use of tonnage / money over a conversion - or not built and have more fleet carriers as and when sub 10,000 ton carriers count towards the totals!

Its just as I said the Hawkins carriers are one of those 'Darlings' of an idea that always gets murdered - or in the case of this thread utterly butchered - by the reality and practicality of the times (and probably correctly)

And the 3 Surviving 'Cruisers' are probably better used as Cruisers

So the six 22,500Ton carriers - are these effectively Sir Arthur Johns (then Director of Naval Construction) very innovative 1930 design which became the 1934 Ark Royal?

When do they get laid down and what happens to the existing carriers?

I have an idea that might allow the Follies to be retained beyond the 135,000 ton carrier limit (which is your 6 x 22.5Kton ships) - which is that Courageous and Glorious are modified as Aircraft repair ships (effectively with a reduced weapon storage etc) with Furious turned into a training ship (obviously without the hindsight of a major War)

However given the angst expended on building or not building HMS Unicorn I can see this Idea not being used

 

[NOMISYRRUC]

The 12-gun IIB armament added 426 pounds to the 8-gun IIA weight, cutting 200 ft/min from the climb rate, but not affecting ultimate level speed. The 4 cannon IIC added an additional 75 pounds to this weight, and the protruding barrels cut 6 mph speed and an added 170 feet/min. climb. It should be noted, however, that the Merlin XX imparted little speed increase, while increasing the Hurri's load carrying capability considerably. It was this factor that lent credence to the Hurri-bomber concept, not readily identified in the Hurricane Is.

That helps my idea that a change in army co-operation doctrine between 1934 and 1936 makes the RAF replace the modified light bombers it used in that role with a mix of Hurricane fighter-bombers and light aircraft (for AOP and LL) in place of the Lysander.