I must have been completely ignorant to this detail up to now, but do i understand correctly that the US WW2 fleet carriers had a SINGLE level hangar, while most japanese and british carriers had double, superimposed hangars? Makes me wonder how the US carriers could carry so many planes, presumably deck parks playing a large part.
I must have been completely ignorant to this detail up to now, but do i understand correctly that the US WW2 fleet carriers had a SINGLE level hangar, while most japanese and british carriers had double, superimposed hangars? Makes me wonder how the US carriers could carry so many planes, presumably deck parks playing a large part.
Yes, US carriers had a single hanger. They could carry so many for a few reasons. One: their hangers were simply bigger. IIRC, the Essex class hanger was roughly 30 meters longer than the hanger on the British Audacious class, despite both ships having similar external dimensions. The hanger was also wider than that found on British carriers. This was due to American hangers being an open design, while British carriers used a closed design due to the way they were armored. And two, yes, American carriers used a permanent deck park for a portion of their air group. The British didn't, at least not until late in the war, and only in the Pacific. I don't believe the Japanese used a deck park either.
Edit: I was able to find the actual dimensions for the Essex class. On the Audacious class carriers, their hanger decks are sorta all over the map. Especially the lower hanger deck.
Essex: 654'x70'x17'6" (45,780 square feet)
Audacious:
Upper Hanger: 364'x67x17'6"
Upper Hanger Extension" 52'x64'x17x6"
Lower Hanger (I've seen 2 different lengths for this hanger, I'll list both) Option 1: 176'x54x17'6"
Option 2: 364x54x17'6"
Option 1 Sq Ft: 37,220
Option 2 Sq Ft: 47,372
Since everything I've ever seen before leads me to believe that the Essex had a significantly larger hanger, my personal opinion is that the first option is more likely for the Audacious class
Also note that US carriers carried extra aircraft at the top of their hangers on railings. I'm not sure if these were fully operable eg just had to put don refuel ream and ready to go or re-assemble their wings and engines as well.
See:
USS Enterprise:
USS Ranger:
I'm not sure though that the later Essexes/Ticonderogas and Midways had this option as well.
Also note that US carriers carried extra aircraft at the top of their hangers on railings. I'm not sure if these were fully operable eg just had to put don refuel ream and ready to go or re-assemble their wings and engines as well.
See:
USS Enterprise:
USS Ranger:
I'm not sure though that the later Essexes/Ticonderogas and Midways had this option as well.
Yes, the Essex class (and presumably the Midway class as well) carried spare aircraft in the rafters of their hangers. The nominal air group for an Essex was 90 aircraft. But they'd carry another 13 spares suspended from the ceiling. AIUI, the spares would need their wings reattached, but that was about it. Obviously as aircraft grew in size, this practice became less and less common until it was abandoned entirely. But they were designed to do this
Also note that US carriers carried extra aircraft at the top of their hangers on railings. I'm not sure if these were fully operable eg just had to put don refuel ream and ready to go or re-assemble their wings and engines as well.
Those aircraft were considered as spares/damage replacements and were not counted in the operational aircraft complement. (IIRC, Friedman lists them separately.) At minimum, they needed wings bolted on, controls connected, etc. Probably a couple of hours work at least.
Some carriers (Ranger, I think) also carried crated aircraft in deep holds.
Also note that US carriers carried extra aircraft at the top of their hangers on railings. I'm not sure if these were fully operable eg just had to put don refuel ream and ready to go or re-assemble their wings and engines as well.
Those aircraft were considered as spares/damage replacements and were not counted in the operational aircraft complement. (IIRC, Friedman lists them separately.) At minimum, they needed wings bolted on, controls connected, etc. Probably a couple of hours work at least.
Some carriers (Ranger, I think) also carried crated aircraft in deep holds.
Closer to 4-8 hours to rig all the control cables. It's kinda (expletives deleted) fiddly. Not something you could really do fast enough to launch a strike, get the second wave up out of the hangar, and take down the spare aircraft to launch a third wave...
Yes, US carriers had a single hanger. They could carry so many for a few reasons. One: their hangers were simply bigger. IIRC, the Essex class hanger was roughly 30 meters longer than the hanger on the British Audacious class, despite both ships having similar external dimensions. The hanger was also wider than that found on British carriers. This was due to American hangers being an open design, while British carriers used a closed design due to the way they were armored. And two, yes, American carriers used a permanent deck park for a portion of their air group. The British didn't, at least not until late in the war, and only in the Pacific. I don't believe the Japanese used a deck park either.
Edit: I was able to find the actual dimensions for the Essex class. On the Audacious class carriers, their hanger decks are sorta all over the map. Especially the lower hanger deck.
Essex: 654'x70'x17'6" (45,780 square feet)
Audacious:
Upper Hanger: 364'x67x17'6"
Upper Hanger Extension" 52'x64'x17x6"
Lower Hanger (I've seen 2 different lengths for this hanger, I'll list both) Option 1: 176'x54x17'6"
Option 2: 364x54x17'6"
Option 1 Sq Ft: 37,220
Option 2 Sq Ft: 47,372
Since everything I've ever seen before leads me to believe that the Essex had a significantly larger hanger, my personal opinion is that the first option is more likely for the Audacious class
Both lower hangar dimensions were correct (and so was 295' & 217') - it just mattered when they were measured, and on which ship.
The 364' for the lower hangar was "as built" for both ships.
During Eagle's 1959-64 modernization her aft lift was restricted to the upper hangar deck and flight deck, with the aft section of the lower hangar and the bottom level of the aft lift well being converted into workshops, accommodation for the increasing number of technical specialists (for the ever-increasing electronics etc on both ship & aircraft), and so on, leaving the lower hangar 172' long.
Ark Royal's 1958-59 "special refit" saw the aft lift similarly restricted, with the aft 69' of the lower hangar being converted to weapons storage & assembly and the bottom level of the aft lift well being used for accommodation - leaving the lower hangar at 295'. The side lift (which served only the upper hangar and flight deck) was also removed.
Ark Royal's 1966-70 "Phantomization" refit saw a further 78' of the aft lower hangar converted to workshops etc, leaving the lower hangar at 217' long.
Both lower hangar dimensions were correct (and so was 295' & 217') - it just mattered when they were measured, and on which ship.
The 364' for the lower hangar was "as built" for both ships.
During Eagle's 1959-64 modernization her aft lift was restricted to the upper hangar deck and flight deck, with the aft section of the lower hangar and the bottom level of the aft lift well being converted into workshops, accommodation for the increasing number of technical specialists (for the ever-increasing electronics etc on both ship & aircraft), and so on, leaving the lower hangar 172' long.
Ark Royal's 1958-59 "special refit" saw the aft lift similarly restricted, with the aft 69' of the lower hangar being converted to weapons storage & assembly and the bottom level of the aft lift well being used for accommodation - leaving the lower hangar at 295'. The side lift (which served only the upper hangar and flight deck) was also removed.
Ark Royal's 1966-70 "Phantomization" refit saw a further 78' of the aft lower hangar converted to workshops etc, leaving the lower hangar at 217' long.
Thanks for that info!! That definitely makes a ton of sense for why the dimensions are all over the place. Talk about no good options for the British. They either reduced their air wing to make space for their personnel, or they crammed their people into increasingly small spaces and/or hot racked. The more I read about the post war Royal Navy carrier fleet, the more I realize just how absolutely blessed the United States Navy was when it came to its carriers. The Essex and Midway classes proved to be exceptionally amenable to being modernized to the point that they didn't even resemble their WWII selves. Whereas the British went through absolute hell trying to modernise their fleet.
Thanks for that info!! That definitely makes a ton of sense for why the dimensions are all over the place. Talk about no good options for the British. They either reduced their air wing to make space for their personnel, or they crammed their people into increasingly small spaces and/or hot racked. The more I read about the post war Royal Navy carrier fleet, the more I realize just how absolutely blessed the United States Navy was when it came to its carriers. The Essex and Midway classes proved to be exceptionally amenable to being modernized to the point that they didn't even resemble their WWII selves. Whereas the British went through absolute hell trying to modernise their fleet.
While this in part conjecture, I would think the reason the British had so many problems was their carriers were designed--from a ship building standpoint-- quite differently from US ones.
The US built carriers where the strength deck was the hanger deck and everything above it was superstructure. The hanger was, for all intents, just a garage plopped on top of the hull with a flight deck on top. US air wing doctrine had all flyable aircraft deck parked on the flight deck. The hanger and areas around it were for maintenance and repairs.
British carrier design made the flight deck the strength deck with the hanger(s) forming part of the hull. This meant unlike the US who could simply raze the hanger and flight deck and plop a totally new design on the hull, the British were stuck, more or less, with the design as originally constructed. Changing it was an expensive and laborious process because they had to make any structural changes such that the strength of the ship's hull wasn't compromised.
This meant that the British couldn't make radical design changes to their carriers like the US did with the Essex and Midway classes. Instead, they were stuck making modest changes and trying to cram everything into the original design they needed.
Honestly has more to do with the fact that the Midways, and to a lesser extent the Essences were more or less Treaty-unlimited designs, whereas the Illustrious class, Indomitable and Implacables were all built within Treaty constraints.
Honestly has more to do with the fact that the Midways, and to a lesser extent the Essences were more or less Treaty-unlimited designs, whereas the Illustrious class, Indomitable and Implacables were all built within Treaty constraints.
That's only part of it. The choice of an armored flight deck limited the size of the ship overall with treaty constraints. But that flight deck was also the strength deck of the ship's hull. That meant the enclosed hanger below it had to be designed as part of the hull and its strength, not something separate from it like on US carriers. That meant you really couldn't make massive changes to the hanger structure or to the flight deck without considering how it would affect the strength girder of the ship.
I also think the British were far more constrained by costs than the US was.
Another design difference was the US sized the Essex class to what was expected to be the maximum number of aircraft then extant and in the near future that the ship could efficiently cycle. For the British, who's doctrine was hangering aircraft between flights, the hanger size dictated the size of the air wing that could be carried. Larger air wing, more hanger necessary. For the US, so long as you could park all the planes somewhere on the flight deck and leave room to take off or land, the hanger didn't have to accommodate all the aircraft aboard.
Yes, later the British adopted the US deck park, and that allowed them to get rid of some hanger space converting it to other purposes without affecting the size of the air wing aboard.
That's only part of it. The choice of an armored flight deck limited the size of the ship overall with treaty constraints. But that flight deck was also the strength deck of the ship's hull. That meant the enclosed hanger below it had to be designed as part of the hull and its strength, not something separate from it like on US carriers. That meant you really couldn't make massive changes to the hanger structure or to the flight deck without considering how it would affect the strength girder of the ship.
Another design difference was the US sized the Essex class to what was expected to be the maximum number of aircraft then extant and in the near future that the ship could efficiently cycle. For the British, who's doctrine was hangering aircraft between flights, the hanger size dictated the size of the air wing that could be carried. Larger air wing, more hanger necessary. For the US, so long as you could park all the planes somewhere on the flight deck and leave room to take off or land, the hanger didn't have to accommodate all the aircraft aboard.
Again, Essex was a post Treaty design, designed outside of the constraints of the Treaty system. That gave American much more flexibility in 1940-41 to design the ships they wanted. Illustrious, Indomitable and Implacable were designed between 1936 and 1938, they cannot be compared to the Essex class, their closest American equivalents are the Yorktown class.
Victorious was razed to the hangar deck and a rebuilt upwards. They didn't need to worry about girder strength that much, the ship was in dry dock.
Which explains far more about the lack of rebuilds than the method of carrier construction.
Again, Essex was a post Treaty design, designed outside of the constraints of the Treaty system. That gave American much more flexibility in 1940-41 to design the ships they wanted. Illustrious, Indomitable and Implacable were designed between 1936 and 1938, they cannot be compared to the Essex class, their closest American equivalents are the Yorktown class.
However, we were comparing the Audacious class* to the Essexes - they were also a "post-treaty" design, and WERE comparable in size to the Essex class.
And it was that difference in structure that limited the scope of their modernizations and caused the reductions in hangar volume.
The scope of the Audacious class modernisations were almost on the level of the Essex class, and they were retained as strike carriers for the rest of their lives. Many of the Essex class were pushed into second line roles (although the US being able to to order a new super carrier every fiscal year between FY52 and FY58 certainly helped).
Its not as if the US retained open hangars and flight decks as superstructure beyond the Midways. I do the British carrier reconstructions were a mistake, if only because the limited resources to hand should have probably have been used for new construction, whereas the US could (and did) afford to to modernise it's existing fleet and build new ships, which it was able to do until a combination Polaris, early guided missile ships, and the sheer cost of Enterprise (the FY58 super carrier) devoured the funds.
The scope of the Audacious class modernisations were almost on the level of the Essex class, and they were retained as strike carriers for the rest of their lives. Many of the Essex class were pushed into second line roles (although the US being able to to order a new super carrier every fiscal year between FY52 and FY58 certainly helped).
Its not as if the US retained open hangars and flight decks as superstructure beyond the Midways. I do the British carrier reconstructions were a mistake, if only because the limited resources to hand should have probably have been used for new construction, whereas the US could (and did) afford to to modernise it's existing fleet and build new ships, which it was able to do until a combination Polaris, early guided missile ships, and the sheer cost of Enterprise (the FY58 super carrier) devoured the funds.
No the Midways has a superstructure flight deck with the strength deck being hanger lever.
It was tge Forestalls and later that need to have tge flight deck as tge Strength deck and that only cause modern jets got so heavy that doing it othersize is weight prohibited.
Is it possible to replace the Iowa's and Alaska's 5-inch / 38-caliber twin mounts with the more modern 5-inch / 54-caliber Mark 45 single-gun turret? I have seen various online conceptual drawings of actual Iowa class modernization proposals with 54-caliber single-gun turrets. I believe Tzoli on DeviantArt has also posted artwork of Iowa class modernization concepts which depicts the Mark 42 or Mark 45 turrets replacing the existing older twin mounts.
No the Midways has a superstructure flight deck with the strength deck being hanger lever.
It was tge Forestalls and later that need to have tge flight deck as tge Strength deck and that only cause modern jets got so heavy that doing it othersize is weight prohibited.
Yes, the Essex class (and presumably the Midway class as well) carried spare aircraft in the rafters of their hangers. The nominal air group for an Essex was 90 aircraft. But they'd carry another 13 spares suspended from the ceiling. AIUI, the spares would need their wings reattached, but that was about it. Obviously as aircraft grew in size, this practice became less and less common until it was abandoned entirely. But they were designed to do this
As designed the Essex class was designed to have the tricing gear necessary to store spare aircraft in the hangar overhead between the beams. But AIUI was omitted on later ships when the flight decks were strengthened.
But the practice of stowing such aircraft was ended during 1942 as a result of early war experience. See section F of the USS Wasp damage report.
When the Midway class were designed alternatives had to be sought. I suspect but have not been able to confirm that having the flight deck Armoured between the forward and after lifts meant that there had to be many more beams to support the weight. More beams meant less space for tricing aircraft between them.
While there is the note about it in the Wasp report linked, the design proposals already had Reserve aircraft storage areas forward and / or aft of the main hangar. In the final design the reserve aircraft storage area was aft of the after lift. As completed it simply became part of the hangar as policy had changed and reserve aircraft were no longer carried. That reserve stowage / aft hangar space was NOT however covered by flight deck armour.
Again, Essex was a post Treaty design, designed outside of the constraints of the Treaty system. That gave American much more flexibility in 1940-41 to design the ships they wanted. Illustrious, Indomitable and Implacable were designed between 1936 and 1938, they cannot be compared to the Essex class, their closest American equivalents are the Yorktown class.
On the Treaty limited 23,000 tons standard displacement in place from 1 Jan 1937 until the outbreak of WW2 Britain had to choose between aircraft numbers as in the double hangar Ark Royal iii of 1938 (60 as completed) and an armoured flight deck and hangar ( Illustrious class 36 later 33 / 45 for Indomitable / 48 for the Implacable as designed). And all determined by hangar capacity.
When design work on the Essex class started in mid-1939, it began at 20,400 tons (or little more than a Yorktown CV-5), being all the surplus tonnage available under the Treaty limits which had been enshrined in US law. From there it grew to the eventual 27,500 tons standard. One of the drivers of the increase in size was to allow a return to a 90 aircraft air group. New aircraft were to be larger than those around which previous carriers had been designed, and already the aircraft complements of the Yorktowns were seen as being affected.
The debate about open/closed/Armoured/unarmoured hangars for RN carriers went on from 1942-45.
DK Brown the naval architect and author devoted several pages to the subject in “Nelson to Vanguard” and summarised the choices thus:-
Open hangar (e.g.Essex) - Good ventilation, easy to warm up planes, Mount large strike, side lifts, more planes.
Closed hangar (e.g. Illustrious / Implacable / Audacious) - Stronger, lighter hull. Much safer against fire, easy to armour, planes protected from weather and some enemy action.
He suggested both navies built the right ships for the wars they expected to fight.
Goodall, in charge of wartime RN ship design, saw the open hangar as having a small lead in operation, closed with a big lead in strength and protection with little difference in fire risk.
Friedman “British Carrier Aviation” noted that an Audacious class had a total hangar area, as designed in 1942 (the design was modified before completion postwar) of just a bit less than 54,000 square feet. A Midway about 50,000 sq ft. But with the double hangar arrangement in the British ship armour was only required for half the area. So an Audacious had 1,975 tons of 4” armour while Midway had 3,130 tons of 3.5” armour on the flight deck. And that Midway armour didn’t even cover all the hangar space when she completed as I noted in my last post.
On the Treaty limited 23,000 tons standard displacement in place from 1 Jan 1937 until the outbreak of WW2 Britain had to choose between aircraft numbers as in the double hangar Ark Royal iii of 1938 (60 as completed) and an armoured flight deck and hangar ( Illustrious class 36 later 33 / 45 for Indomitable / 48 for the Implacable as designed). And all determined by hangar capacity.
When design work on the Essex class started in mid-1939, it began at 20,400 tons (or little more than a Yorktown CV-5), being all the surplus tonnage available under the Treaty limits which had been enshrined in US law. From there it grew to the eventual 27,500 tons standard. One of the drivers of the increase in size was to allow a return to a 90 aircraft air group. New aircraft were to be larger than those around which previous carriers had been designed, and already the aircraft complements of the Yorktowns were seen as being affected.
The debate about open/closed/Armoured/unarmoured hangars for RN carriers went on from 1942-45.
DK Brown the naval architect and author devoted several pages to the subject in “Nelson to Vanguard” and summarised the choices thus:-
Open hangar (e.g.Essex) - Good ventilation, easy to warm up planes, Mount large strike, side lifts, more planes.
Closed hangar (e.g. Illustrious / Implacable / Audacious) - Stronger, lighter hull. Much safer against fire, easy to armour, planes protected from weather and some enemy action.
He suggested both navies built the right ships for the wars they expected to fight.
Goodall, in charge of wartime RN ship design, saw the open hangar as having a small lead in operation, closed with a big lead in strength and protection with little difference in fire risk.
Friedman “British Carrier Aviation” noted that an Audacious class had a total hangar area, as designed in 1942 (the design was modified before completion postwar) of just a bit less than 54,000 square feet. A Midway about 50,000 sq ft. But with the double hangar arrangement in the British ship armour was only required for half the area. So an Audacious had 1,975 tons of 4” armour while Midway had 3,130 tons of 3.5” armour on the flight deck. And that Midway armour didn’t even cover all the hangar space when she completed as I noted in my last post.
The problem was, in combat the closed hanger proved to be a HUGE liability. So much so that the RN started having their armored carriers lower one elevator during air attacks to give a path for bombs penetrating the "armored" flight deck a path to ventilate the explosion.
HMS Illustrious is a good example of this.
This old chestnut again. Once any hangar was penetrated it became something of a liability. The object of the armoured flight deck was to keep out as much as possible and to protect the rest of the ship from its volatile contents. There were limits to that which were recognised in the design spec.
You will find that the open hangar US designs were little better at venting blast and preventing flight deck / hangar damage.
USS Enterprise damage report Aug 1942 Battle od Eastern Solomons. Note the flight deck aft around No.3 elevator
Battle damage inflicted on USS Enterprise CV-6, 14 May 1945, off Kyushu, Japan.
www.cv6.org
This is a photo of showing the deflection to her flight deck as a result of that kamikaze hit.
Again re the Midway I'm not sure what your point is. The Yorktown class and Wasp carried their armour (1.5") on the "Protective deck" deeper in the ship. The Essex class added a 1.5" hangar deck to the protective deck (1.5"). Midway further improved on that with Protective deck (third deck) armour (1.75"), hangar deck armour (2") and flight deck armour (3.5") but only between the lifts as in Illustrious & Taiho.
Midway's lifts, as those of the Illustrious class were unarmoured with the lift spaces in both ships being closed off from the hangar itself by armoured doors. Their hangar sides, while still technically "open" in Midway were far more enclosed than in previous classes by virtue of all those 5"/54 gun mounts along her sides.
As the first 2 Midways did not complete until Sept 1945, they were never tested in action so we really have no idea how they would have performed relative to an Illustrious class of about half the size.
As for the illustrious class they too had armour at hangar deck level. 1" NC within the hangar space and 3" outboard. Here is a diagram of their armour layout taken from Ross Watton's Anatomy of the Ship book that appears on the armoured carriers website. (the deck images are respectively top to bottom, flight deck, first gallery, second gallery, hanagr & upper deck. There was also a 3" armour layer on the main deck, one deck under upper deck above the steering compartment). Note that the lifts themselves were not armoured.
The after lift was destroyed by bombs droping on it. The bomb that did the most damage to Illustrious in Jan 1941 when she was off Malta, was a 1000kg (2,200lb) bomb that punched through her 3" armoured flight deck to explode 2ft above the hangar deck. In doing so it penetrated that deck. The explosion wrecked the after hangar section and started fires on the deck below. Some splinters penetrated deeper into the ship. And the blast wrecked the fire curtains forward and damaged the forward lift. But most importantly it didn't breach the hangar walls.
Note the size of the bomb. The Staff Requirement called for the ability to keep out a 500lb SAP bomb dropped from 7,000ft or a 250lb bomb dropped from 11,500ft or a 1,000lb AP bomb from 4,500ft. Her armour was never intended to keep out a bomb of that size.
Perhaps the surprise should be that Illustrious managed so much on a Treaty limited 23,000 tons standard displacement when compared to the later non-Treaty Midway at 45,000 tons, whose design incidentally owed much to the USN study of the damage to Illustrious & Formidable when they were being repaired at Norfolk in 1941.
With Taiho, the Japanese made efforts to protect the lifts (they comprised 2 layers of 25mm DS steel). But each platofrm then weighed 100 tons. they also made some effort to address the issue of blast in the upper hangar with "blow out" panels in the hangar walls, which in the end proved ineffective.
When it came to the design of the Forrestal class BuOrd wanted armour but noted that "It is impracticable to carry enough armor to keep AP bombs from penetrating the flight deck, provided they are dropped from sufficient altitude to acquire the necessary velocity...." (see Friedman US Carriers)
I must have been completely ignorant to this detail up to now, but do i understand correctly that the US WW2 fleet carriers had a SINGLE level hangar, while most japanese and british carriers had double, superimposed hangars? Makes me wonder how the US carriers could carry so many planes, presumably deck parks playing a large part.
To address another factor that people haven't mentioned yet, besides deck parks and the hangers simply being larger, the Japanese didn't fold their planes and the Brits had strict fire safety standards in the first few years of the war that reduced parking density. So the Americans just plain parked their planes more densely than the other two carrier powers did.
Notably, the Illustrious class jumped from 33 to 45 aircraft stowed in the hanger just by relaxing those fire safety anti-density measures.
The increased capacity had nothing to do with reduced fire safety. Aircraft dimensions were the biggest factor.
Hangar was 456×62.
33 in Illustrious was based on Albacore / fulmar sized aircraft. 11 rows 3 abreast. Avengers / corsair don't buy enough space for another 12 aircraft in the hangar. Can still only pack them 3 abreast. Might gain one row.
The difference came with the extra half Hangar in Indomitable and the Implacables
Indomitable
upper 416×62
Lower 208×62
Hangar capacity was 45 based on Albacore sized aircraft .
As the war went on deck parks became more common .
The Implacables also carried Seafire iii 1944/45. Being only 13.5ft wide folded they could be packed in 4 abreast instead of 3 abreast for other types.
I think one issue is that the USN was predominantly looking to operations in the Pacific, vs the North Atlantic, and that tended to make the Admiralty more, perhaps excessively, concerned with weather damage to aircraft, with the result that they did not view a deck park as practical. I suspect that that also influenced Admiralty decisions on how weather-tight the hangar deck was.
In one of the articles on post-WW2 USN carrier design published in Warship International, the author (I can't recall whether it was Friedman or Polmar, but I'm fairly sure it was the later) reported that USN carrier captains had problems with weather damage to their ships in the North Atlantic where they never had such issues in the Pacific.
--------------
A second issue is that the RN also expected to routinely operate its carriers within range of land-based air; this did not seem to be an expectation of the USN, which was more concerned with the IJN than with, say, the various land-based air forces the RN was expected to have to deal with in the North Sea and the Mediterranean.
The increased capacity had nothing to do with reduced fire safety. Aircraft dimensions were the biggest factor.
Hangar was 456×62.
33 in Illustrious was based on Albacore / fulmar sized aircraft. 11 rows 3 abreast. Avengers / corsair don't buy enough space for another 12 aircraft in the hangar. Can still only pack them 3 abreast. Might gain one row.
The difference came with the extra half Hangar in Indomitable and the Implacables
Indomitable
upper 416×62
Lower 208×62
Hangar capacity was 45 based on Albacore sized aircraft .
As the war went on deck parks became more common .
The Implacables also carried Seafire iii 1944/45. Being only 13.5ft wide folded they could be packed in 4 abreast instead of 3 abreast for other types.
HMS Illustrious: September 1940 to January 1941 * This conformed with the design specification, below-decks stowed, fire-safety spaced air group of 33 aircraft, rising to 41 for the strike against Taranto.
806 Squadron: 15 Fulmar MkI
816 Squadron: 9 Swordfish MkI
819 Squadron: 9 Swordfish MkI
+ 813 Squadron: 4 Swordfish, 2 Sea Gladiator (From Eagle for Taranto only)
+ 824 Squadron: 2 Swordfish (From Eagle for Taranto only)
HMS Illustrious: February 1942 to August 1942 * Relaxation of stowage spacing standards allowed the carrier a total air group of 45 aircraft.
881 Squadron: 12 Martlet MkII
882 Squadron: 6 Martlet MkII
806 Squadron: 6 Fulmar MkII (Joined in May)
810 Squadron: 9 Swordfish MkI
829 Squadron: 12 Swordfish MkI
Those are the air group sizes. The way it reads is the air group size for Taranto increased not that the expanded group fitted in the hangar. Not all the 41 could be or were carried in the hangar. I referred to deck parks.
Do the maths. I gave the hangar size.
Swordfish and fulmar folded width only allow stowage 3 abreast. Both were just over 17ft folded. Hangar width = 62ft
Fulmar- 15÷3=5 × 40 feet long = 200ft
Swordfish - 24÷3=8 x 36 feet long = 288 feet
Total length of hangar required 488 feet plus about 1.5-2 feet working room between rows. Adds another 21-28 ft to the length required to stow them all in the hangar. So 509-516 ft of hangar required.
Folded these aircraft occupied very rectangular spaces. So no dovetailing of noses, tails etc.
Hangar length available = 456 ft
See the problem? You are 60ft short. Add to that that the Sea Gladiators don't fit down the lifts and we're permanently stowed on deck behind the island where they appear in photos
I've not done the maths for 1942 but the first thing is that the Martlets were physically smaller. Folded 30x14.3ft. So 10 ft shorter than a Fulmar.
So squeezing in 4 abreast probably possible but tight hence the ref to relaxed stowage. 1ft between aircraft and hangar walls.
An additional concern for everyone who isn't US: extreme aircraft capacity is nice, but where are the aircraft? Be it production bottlenecks, interservice rivalry, or organizational reasons - the end result was US even in 1942 managed to fill their decks to full capacity (even if only just so in autumn 1942, when USN was close to desperate).
But what was desperation for US(just one complement w/o replacements) was better than the norm for others. IJN and even RN carriers more often than not didn't carry full aircraft complements; and neither could afford to lose aircraft in quantities USN was often losing due to heavy weather/typhoons. It may sound cynical, but RN/IJN strike carrier losses made the situation somewhat easier for both.
Others(Germany, France, Italy) had it even worse - the whole German carrier program got rather famously canceled because, among other reasons, no one could be sure about her airwing even being available to KM. Is 4x or 5x hangar capacity that important then?
The point is - others may have not even aimed for US hangar space and capacity.
1: The Midway and Malta designs went through some very large changes due to design information exchanges between the two designs teams - some of these discussions are held in the TNA in UK.
2: The Audacious class benefitted, eventually, from the photo-elastic modelling of hull stresses which allowed a closed box/deck design to efficiently mount a side lift.
3: The Armoured carriers had fire curtains which divided the main hangars into three. The various Aircraft Carrier Handbooks list aircraft capacities for each section and the deck park. IF (!) Implacable loaded only Seafires, they could take over 100.
4: There were two big problems with British Aircraft carriers in the later stages of the war ;
a: Fuel storage - due to earlier bad experience the RN had extensive safety precautions to fuel storage which restricted onboard capacity.
b: As mentioned a relative shortage of aircraft (only really overcome at the very end of the war). Partly this was down to the relative low priority given to naval aircraft production in the UK, and partly because over two years the US rejected most of the bids for lend-lease aircraft. This looks bad, due to the excess numbers USN aircraft available, but at the time of the bids the USN was still feeling the effects of early war losses. Thankfully theUSN rejection of the Corsair made up for some of the problems.
2: The Audacious class benefitted, eventually, from the photo-elastic modelling of hull stresses which allowed a closed box/deck design to efficiently mount a side lift.
And they were designed that way from the outset. Those in Ark Royal and Hermes had to be redesigned into the ships after their hulls were substantially complete.
Ark's could only go to upper hangar level due to insufficient freeboard at lower hangar level.
Question regarding Super Carrier hanger subdivision. The Nimitz Class has two sets of armored door to divide the hanger into three spaces in the event of a mass configuration. The Ford Class has only one set of doors. Was it a top weight issue? What is the configuration on the QE & PoW? Does anyone know why these design choices were made? The Ford & QE classes take into account decades of carrier hanger configuration evolution. Is the best design or the best design for the money?
Question regarding Super Carrier hanger subdivision. The Nimitz Class has two sets of armored door to divide the hanger into three spaces in the event of a mass configuration. The Ford Class has only one set of doors. Was it a top weight issue? What is the configuration on the QE & PoW? Does anyone know why these design choices were made? The Ford & QE classes take into account decades of carrier hanger configuration evolution. Is the best design or the best design for the money?
This is a link to a Navy Lookout article from 2018 discussing the survivability of the QE class. The article finishes with the comment:-
"This cursory assessment of a complex subject, using only public domain sources reveals the QEC, while not unsinkable, are resilient platforms and that have been constructed with a good balance between cost with survivability."
Dealing specifically with the question of division of the hangar space, it can be divided into 3 sections with fire curtains dropped from the hangar overhead (they look to me a bit like steel security shutters for industrial premises). They are visible in the stowed position in some of the hanger photos in this Navy Lookout article (scroll down the page). Look like they are held in place by guide rails in the hangar sides.
From the Naval Engineers Journal, May 2001, concerning CVNX ECBL Study 5, one of the predecessors to the Ford class, back when the original plan for the program was to spread the new technology across two Nimitz class carriers, before combining it all on a new larger monohull CVN design:
The Hangar Bay (see Figure 4) was sized similar to the Nimitz class; however, instead of having three bays divided by two hangar division doors, Study 5 has two aircraft servicing bays subdivided by one hangar division door. This choice was driven by the placement of the enlarged starboard aircraft elevators, and their structural impacts on the large elevator openings in the ship's hull and hangar side bulkhead. Damage control in the reduced number of bays was of concern, but historical data found in earlier carrier designs that also had only one subdivision door, indicated that this was not a problem.
The comment about "earlier carrier designs that also had only one subdivision door" is probably a reference to Midway. She started with 4 when constructed, but lost the ones just aft of the forward lift and forward of the after lift in her 1955-57 refit. She then lost another in her 1966-70 refit as a weight saving measure.
From the Naval Engineers Journal, May 2001, concerning CVNX ECBL Study 5, one of the predecessors to the Ford class, back when the original plan for the program was to spread the new technology across two Nimitz class carriers, before combining it all on a new larger monohull CVN design:
The comment about "earlier carrier designs that also had only one subdivision door" is probably a reference to Midway. She started with 4 when constructed, but lost the ones just aft of the forward lift and forward of the after lift in her 1955-57 refit. She then lost another in her 1966-70 refit as a weight saving measure.
The Essex class CVs had three hangar bays, with two subdividing doors.
The early configuration of the three Midway class CVs is unknown to me, but after her major 1966-70 modernization Midway had only two hangar bays, with one subdividing door.
The Forrestal and Saratoga had three hangar bays, with two subdividing doors - likely due to their original axial flight deck configuration.
Ranger and Independence had only two hangar bays, with one subdividing door, and were designed from the start with an angled flight deck.
Kitty Hawk and Constellation had only two hangar bays, with one subdividing door.
I don't know if America and JFK had two or three hangar bays.
Enterprise had only two hangar bays, with one subdividing door.
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