Max CAG for a Courageous class carrier without deck parking?

RCAFson said:

If the plane can't fly or no maintenance carriers were available , then the maintenance would be done on the fleet carrier. However if a maintenance carrier was in company.

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The British had only one maintenance carrier, HMS Unicorn (I72) and that wasn't completed until spring 1943. With no maintenance carrier to serve the Courageous class CAG, I assume aircraft needing maintenance were either repaired on-board, flown ashore or chucked overboard.

jetcal1 said:

I am aware that the CVE/CVL carriers were indeed used as floating replacement aircraft depots.
But, I must be confused, because the main deck of every US CV since at least the Essex .

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And when was the Essex designed?
Unicorn was designed in 1936-1937, same time as the Illustrious class was desgned/started, and commissioned in 1943, so it was pre-war design and tactics

Freebird said:

And when was the Essex designed?
Unicorn was designed in 1936-1937, same time as the Illustrious class was desgned/started, and commissioned in 1943, so it was pre-war design and tactics

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Since the Essex was ordered in 1940, and assuming there were design competitions, and review by BuShips and BuAer, I'd assume the design studies/proposals started around 1937-38 which is probably close enough to make them contemporary designs. I'd also call the Essex a pre-war design.

Having said that, the design philosophies of the two navies were different. The USN designed for Blue Water, the RN for Littorals.

jetcal1 said:

Having said that, the design philosophies of the two navies were different. The USN designed for Blue Water, the RN for Littorals.

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Illustrious agreed, but I'd say the Courageous class were designed to field the largest possible air group with less thought to protection. The Courageous class have more in common with the Yorktown class than the Illustrious class.

Admiral Beez said:

Illustrious agreed, but I'd say the Courageous class were designed to field the largest possible air group with less thought to protection. The Courageous class have more in common with the Yorktown class than the Illustrious class.

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Armor does indeed appear to be similar.

jetcal1 said:

Armor does indeed appear to be similar.

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Here's a pic of Furious torn down to what I believe is the armoured deck. Above here it's only sheet steel.



HMS Furious

This site on British naval warships over hundreds of years is a fascinating source of info. Here's HMS Glorious, showing the armoured deck below the lower flight deck.



Sections plan of HMS Glorious (1916)

Admiral Beez said:

According to Wikipedia, HMS Courageous and Glorious had two hangars of 16 feet high, 550 feet long and 50 feet wide, with two 46-by-48-foot lifts. That 55,000 sqft of space, minus 8,840 sqft for the four hangar level lift openings, for a total of 46,160 sqft for hangar space, not including fire curtains, etc. This compares well against the 28,000 sqft hangar of the Illustrious class.The British had only one maintenance carrier, HMS Unicorn (I72) and that wasn't completed until spring 1943. With no maintenance carrier to serve the Courageous class CAG, I assume aircraft needing maintenance were either repaired on-board, flown ashore or chucked overboard.

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I'm coming late to this discussion but would like to add some points not mentioned.

Firstly RN carrier capacity in terms of aircraft was driven by hangar space not flight deck space. Why? Because the RN intended to operate, not in the relatively benign waters of the Pacific, but in some of the roughest seas on the planet ie the North Sea and North Atlantic. Even the Med has frequent storms. The lightly constructed aircraft of the post WW1 period would not have stood up well to a battering from the regular gales in these waters and remained serviceable for long.

That also led to another feature of British carriers. The landing circle, the point at which a landing pilot was aiming, is further forward than on US ships.Why? In rougher seas ship motion is reduced nearer the centre of the ship. So while British carriers were shorter to begin with, the effective landing area was shortened still further.

Finally deck parks would have been plain unsafe on a British carrier between the wars. Why? Arrester gear and barriers.

Britain experimented with various transverse and longitudinal arrester systems, but these were removed from the early carriers between 1923 and 1926 and there was then a period when there was no means of arresting aircraft fitted. This was not seen as a problem due to operating methods and the generally light aircraft of the period having short stopping distances. Courageous was fitted with a trial single wire set of what might be considered the modern transverse hydraulic arrester gear in 1930 but it wasn't generally fitted until later. Hermes, Furious, Courageous and Glorious got it in 1933, Eagle in 1936 and Argus in 1938.

The first barrier, other than some experimental set ups on Furious and Vindictive when they had separate landing on decks, was in Ark Royal from 1939. It was not retrofitted to any of the older ships despite there being some discussion of doing so in Furious and Eagle in 1941 following requests from their COs.

So deck parks of any size in the 1920s and 1930s would not have been safe from damage in the event of an aircraft landing long or missing an arrester wire, there being nothing to separate the landing area from the parking area, however small.

It also helps explain the cruciform lifts on British carriers. To speed up flight deck operations aircraft would be struck down into the hangar and the wings folded there rather than on the flight deck.

From about 1932 the RN was operating large ranges of aircraft, for take off only, in exercises involving 2-3 carrier groups simultaneously. There are plenty photos around to demonstrate this. Multi carrier operations were not something the USN practiced until 1943.

So for Furious, Courageous and Glorious to have operated any form of deck park inter war there would have needed to have been changes to both the ships and RN operating procedures.

Admiral Beez said:

The British had only one maintenance carrier, HMS Unicorn (I72) and that wasn't completed until spring 1943. With no maintenance carrier to serve the Courageous class CAG, I assume aircraft needing maintenance were either repaired on-board, flown ashore or chucked overboard.

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The need for a maintenance carrier grew out of the RN experience in the Med in 1935/36 during the Abyssinian Crisis. It was then estimated that a carrier could lose approx 20% of its air Group very quickly and have another 10% grounded through the need for major repairs that could not be carried out on the carrier itself. This was foreseen as a real problem when the Illustrious class Armoured carriers were being designed as they only held 33-36 aircraft to begin with.

It should be noted that British carriers had workshops to keep aircraft flying. Spare engines, propellers and even flying surfaces were carried to patch damaged aircraft up. But these spares were not limitless.

So design of Unicorn began in Nov 1937, she was ordered in April 1939 as part of the 1938 shipbuilding programme and completed in March 1943. However initially she operated as an operational carrier, most noticeably at Salerno in Sept that year.

It was only at the very end of 1943, just before sailing for the Indian Ocean, that she took up her maintenance role in support of Illustrious.

Unicorn however was not the only RN maintenance carrier. There were two others.

In late 1943 with the planned expansion of the RN carrier force and the prospect of operations in the Far East, the decision was taken to convert the Colossus class carriers Edgar and Mars laid down in 1942 at Vickers Armstrong Tyne and Barrow respectively to maintenance carriers and to rename them Perseus and Pioneer. The latter completed in Feb 1945 in time to join the BPF at Manus in June to support the final wartime operations of that fleet in Japanese waters. Perseus followed in Oct 1945.

A number of other merchant hulls were also taken over in 1944 for conversion to support FAA operations in the Pacific. Deer Sound, Cuillin Sound and Holm Sound were intended as aircraft component repair ships while Beauly Firth, Solway Firth and Moray Firth were aircraft engine repair ships. Only the very first named of these became operational in WW2 with others en route when it ended. These were intended to operate in conjunction with the 3 aircraft maintenance ships in forward anchorages to keep the fleet supplied with aircraft. Replacement aircraft would then be ferried forward to the operational carriers by CVE.

jetcal1 said:

Since the Essex was ordered in 1940, and assuming there were design competitions, and review by BuShips and BuAer, I'd assume the design studies/proposals started around 1937-38 which is probably close enough to make them contemporary designs. I'd also call the Essex a pre-war design.

Having said that, the design philosophies of the two navies were different. The USN designed for Blue Water, the RN for Littorals.

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The Washington Treaty of 1922 limited the US carrier force to 135,000 tons. The last of this tonnage was used up in building CV-7 Wasp starting in 1936. While that Treaty expired at the end of 1936 the London Treaty of 1936 placed a limit of 23,000 tons on individual carriers but no overall limit on carrier tonnage.

But in May 1938 the US Congress approved an increase in US carrier tonnage to 175,000 tons. That allowed the USN to begin planning 2 more carriers. At that time however design capacity was limited and Battleships had priority. They decided that the best that could be achieved on 20,000 tons, given design constraints, was to order a repeat Yorktown class. That ship, with a few modifications, became CV-8 Hornet ordered on 30 March 1939.

It was only at that point, mid-1939, that the USN began to turn its attention to how best to utilise the available and permitted 20,400 tons of carrier capacity and the design of what became the CV-9 Essex class began. A few months later WW2 breaks out and the Treaty limit of 23,000 tons disappears. And then in July 1940 the Two Ocean Navy Act is passed authorising the USN procure more than the previously planned two carriers.

The build contract for Essex CV-9 was awarded in July 1940 before the design itself was completed. Between 1939 and 1940 it went through various iterations including one with 2.5" of armour on the flight deck and grew in size from the initial 20,400 ton limit to the eventual 27,000 ton design. The main aim of the increase in size was to increase aircraft capacity to 90 (due to increases in aircraft size in the late 1930s the capacity of the Yorktown class had had to be reduced). Essex was eventually laid down in April 1941 with a planned completion date in Q1 1944. The outbreak of war with Japan saw the build accelerated and she completed in Dec 1942.

In some ways the Essex was a pre-war design, the design process having occurred before radar became more than an experimental device and before the experience of the RN in the Med in 1941 could be taken on board, let alone that of the 1942 Pacific carrier battles. But the design was significantly modified for later ships. For example the forward avgas tanks were moved aft in later ships where they were better protected behind the Armoured belt and an extra layer of side protection compartments.

The difference in philosophy between the two navies isn't so much blue water / littoral as the nature of the sea conditions in which the navies expected to operate. There is generally far more good weather to be found in the central Pacific than there is in the North Atlantic/North Sea, which are some of the worst bits of sea/ocean weather wise in the world. Even the South China Sea, where Britain envisaged facing Japan inter-war, seems to rate worse than the Central Pacific.

EwenS said:

The need for a maintenance carrier grew out of the RN experience in the Med in 1935/36 during the Abyssinian Crisis. It was then estimated that a carrier could lose approx 20% of its air Group very quickly and have another 10% grounded through the need for major repairs that could not be carried out on the carrier itself. This was foreseen as a real problem when the Illustrious class Armoured carriers were being designed as they only held 33-36 aircraft to begin with.

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Had Courageous and Glorious survived into 1941-43 would you see Hermes, Eagle or Argus being converted to a maintenance carrier?

Admiral Beez said:

Had Courageous and Glorious survived into 1941-43 would you see Hermes, Eagle or Argus being converted to a maintenance carrier?

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Whether or not Courageous and / or Glorious survived into 41-43 I really can't see any of these old ships being converted to maintenance ships. Just look at the historical position. There was no need to consider more maintenance carriers before the end of 1943 due to the proximity of operating areas to the considerably expanded RN shore base organisation. It only begins to change with the RN looking forward to Pacific operations. And look at the ships themselves -

Argus spent most of her wartime life as an aircraft ferry or training carrier. She was worn out by the end of 1943 and good for nothing more than use as an accommodation ship. The opportunity existed but the RN passed. I don't see anything changing in your scenario.

Eagle by the time of her last refit, Oct 1941-Jan 1942 was pretty much worn out after some 20 years of service. Friedman notes she needed new boilers. And her hangar aircraft capacity was about half that of a Colossus, space which was badly needed for the maintenance carrier role. Peacetime plans in 1939 would have seen her gone from the fleet by 1942 as the Illustrious class entered service. I see nothing that would make her a suitable candidate.

The main problem I see with Hermes as a maintenance carrier is again her size, even smaller than Eagle.

And by the time Furious ceased to be an operational carrier in Sept 1944, her machinery was too clapped out to use her for anything else.

In these maintenance carriers the issue was hull and hangar volume. Much of the hangar overhead in the gallery was put to use. But these old carriers didn't have the same depth of space to allow that. Unicorn had two hangars. Perseus & Pioneer had additional superstructure built on the flight deck to accommodate things like an oxygen plant. So I really don't see the old ships as being worth the cost and time of conversion.

Maintenance "carrier" needs to keep up with fleet in general and/or move part way around the world.
As noted by EwenS, spending money to convert a worn out ship (or nearly worn out) is a bad investment as you are gambling your operational readiness of your combat carriers on 15-20 year old boilers, turbines and condensers.

A Maintenance carrier parked in Portsmouth harbor doesn't extend the reach of the British Carrier fleet one mile.

At some point you just have to give up on some of the old ships and send them to the scrappers.

Replacing major items in an existing hull can be more labor intensive than putting the same items in a new hull as the items (boiler, turbines, etc) are put in with the hull at the proper stage of construction to give the best access.