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 Naval WWII
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anemone
DONCASTER S. YORKS, UK
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The Case For(Or Against) Armoured Flight Decks in WW2
Posted on: 9/29/2017 6:46:12 AM
The Royal Navy of the 1930s resolved to build a carrier not merely capable of surviving sustained air attacks, but of continuing air operations after taking a measure of battle damage.Such a carrier needed to be able to protect its aircraft, to provide fleet reconnaissance and trade protection, as well as offer air patrol and combat strike functions.

The challenge was to provide this within restrictions defined by Washington Treaty limits.This was achieved by an ingenious – and for some considerable time Top Secret - design which incorporated an “armoured box” hangar into a strength deck that was also the flight deck.It was an innovation which provided considerable weight savings for such a heavily armoured structure. But it came with a cost.To maintain stability, the second hangar had to be discarded. As a result, the Illustrious Class would have to be limited to 33 internal stowage spaces for aircraft.

FLIGHT DECK
That the Illustrious Class had an “armoured flight-deck” is something of a misstatement.What made the class so unique was an armoured box incorporating the centre of the flight deck between the lifts which enclosed the aircraft and machinery spaces within a protective “cocoon”. The lifts themselves were not armoured and nor was the flight deck fore and aft. In effect, the 3in armour covered 62 per cent of the flight deck and weighed 1500 tons. Much of the remainder was 1.5in toughened structural steel.

The United States Navy built its flight decks as though they were part of the vessels superstructure. British carriers, including Ark Royal, incorporated them as their primary strength deck. As a result the flight decks were an integral part of the ship’s hull. This is why the flight deck around the fore and aft lifts was rated as 1.5in armour – for strength reasons, not as protection.While of roughly similar weight to their United States Washington Treaty contemporary (the USS Yorktown Class) and HMS Ark Royal , the Illustrious Class were smaller ships. This was compounded during the early war years by the provision of extensive “round downs” on the bow and stern to improve air flow over the deck.

All three ships underwent flight deck rebuilds to improve the operational flight deck space during the war years. Eventually, the usable length of HMS Illustrious herself was boosted to 740ft. Initially, only 620ft had been available.Where Ark Royal had a freeboard to the flight deck of some 60ft, the deletion of the second hangar deck from the Illustrious class in order to preserve stability reduced this height above the water to 38ft.The flight deck and aircraft facilities of the class were initially designed to operate 11,000lbs aircraft with an maximum take-off weight of 14,000lbs. This was steadily upgraded throughout the wae.

Regards

Jim
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Pro Patria Saepe Pro Rege Semper

anemone
DONCASTER S. YORKS, UK
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Re: The Case For(Or Against) Armoured Flight Decks in WW2
Posted on: 9/29/2017 8:40:18 AM
Britain operated squadrons of an optimal twelve aircraft, divided into four “sections” of three aircraft. Each “section” had a designated colour and each section aircraft a number.Illustrious was designed with stowage allocated for 33 aircraft.

Many reports state this was 36, but a look at the original lash-down arrangements shows provision for 12 aircraft in hangars A and C (named divisions based on the fire curtain compartments), and only 9 in Hangar B.

Ark Royal’s intended total stowage capacity was 72 aircraft (though fewer could be operated). The Illustrious’ US contemporary, USS Enterprise, was carrying more than 70.

Regards

Jim
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Michigan Dave
Muskegon, Michigan, MI, USA
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Re: The Case For(Or Against) Armoured Flight Decks in WW2
Posted on: 9/29/2017 8:59:21 AM
Jim,

The problem with the RN following the Washington Naval Treaty, is the Kreigsmarine, & the IJN sure as hell didn't!!!!!!!

MD
---------------
"The brave men, living and dead, who struggled here, have consecrated it, far above our poor power to add or detract."

OpanaPointer
St. Louis, MO, USA
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E-9 Sergeant Major
Posts: 750

Re: The Case For(Or Against) Armoured Flight Decks in WW2
Posted on: 9/29/2017 9:39:31 AM
If the USN had built with metal decks would we have been short a carrier at Midway?

anemone
DONCASTER S. YORKS, UK
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Re: The Case For(Or Against) Armoured Flight Decks in WW2
Posted on: 9/29/2017 10:20:53 AM
Opana- Lexington was attacked by 19 D3As. One was shot down by the CAP before it could drop its bomb and another was shot down by the carrier.

She was hit by two bombs, the first of which detonated in the port forward five-inch ready ammunition locker, killing the entire crew of one 5-inch AA gun and starting several fires.

The second hit struck the funnel, doing little significant damage although fragments killed many of the crews of the .50-caliber machine guns positioned near there.

Had she had an armoured deck- she would IMHO have survived. HMS Ilustrious survived two German 1000lb bomb hits

regards

Jim
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Pro Patria Saepe Pro Rege Semper

OpanaPointer
St. Louis, MO, USA
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Re: The Case For(Or Against) Armoured Flight Decks in WW2
Posted on: 9/29/2017 11:00:08 AM
Sorry, I didn't mean "survive", I meant "be ready for service".

anemone
DONCASTER S. YORKS, UK
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Re: The Case For(Or Against) Armoured Flight Decks in WW2
Posted on: 9/29/2017 11:28:24 AM
Here I have to be scrupulously fair -although HMS Illustrious was able to sail from Malta after her damage-she had to be repaired-it is then most likely that Lady Lex would would not have been fit for Midway-also having to undergo repairs.

The steel box hangar overlain by a steel flight deck of the Illustrious class aircraft carriers saved them from being sunk. UK just could not afford to lose carriers after the careless loss of the converted heavy cruisers Courageous,Glorious and the more modern Ark Royal.

Regards

Jim
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Pro Patria Saepe Pro Rege Semper

OpanaPointer
St. Louis, MO, USA
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Re: The Case For(Or Against) Armoured Flight Decks in WW2
Posted on: 9/29/2017 12:10:35 PM
You reinforce opinions I've seen elsewhere. Thanks.

R Leonard
Richmond, VA, USA
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Re: The Case For(Or Against) Armoured Flight Decks in WW2
Posted on: 9/29/2017 11:19:55 PM

Quote:
Lexington . . . was hit by two bombs, the first of which detonated in the port forward five-inch ready ammunition locker, killing the entire crew of one 5-inch AA gun and starting several fires.
The second hit struck the funnel, doing little significant damage although fragments killed many of the crews of the .50-caliber machine guns positioned near there.
Had she had an armoured deck- she would IMHO have survived. HMS Ilustrious survived two German 1000lb bomb hits


You seem to have forgotten a couple of torpedo hits . . . you know, the ones that started the av gas leaks? Not much an armored flight deck/hangar box can do about those nor even some rather bad damage control decisions.

I'd suggest that av gas fumes/vapors building up in a steel box hangar might have a tendency to make a pretty big bang, given the opportunity.

anemone
DONCASTER S. YORKS, UK
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Re: The Case For(Or Against) Armoured Flight Decks in WW2
Posted on: 9/30/2017 3:43:18 AM
No RL- I did not forget Lexington's torpedo hits -I was comparing the damage done by bomb hits on both ships only-the theme of this thread is to do with flight deck construction.

Regards

Jim
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Pro Patria Saepe Pro Rege Semper

Michigan Dave
Muskegon, Michigan, MI, USA
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Re: The Case For(Or Against) Armoured Flight Decks in WW2
Posted on: 9/30/2017 8:47:15 AM
Sad ending to the USS Lexington, It breaks my heart to see the Lady Lex like this!?

[Read More]

Respects,
MD
---------------
"The brave men, living and dead, who struggled here, have consecrated it, far above our poor power to add or detract."

anemone
DONCASTER S. YORKS, UK
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Posts: 6636
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Re: The Case For(Or Against) Armoured Flight Decks in WW2
Posted on: 9/30/2017 8:57:06 AM
Sad-Yes indeed MD- but what is your opinion of armoured flight decks on WW2 aircraft carriers.????


Regards

Jim
---------------
Pro Patria Saepe Pro Rege Semper

Michigan Dave
Muskegon, Michigan, MI, USA
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Re: The Case For(Or Against) Armoured Flight Decks in WW2
Posted on: 9/30/2017 9:22:43 AM
Jim,

I think armored flight decks are a positive, several US Carriers benefited from them along with great damage control teams, example the USS Yorktown, repaired in time to be a big help at the battle of Midway!

Regards,
MD
---------------
"The brave men, living and dead, who struggled here, have consecrated it, far above our poor power to add or detract."

anemone
DONCASTER S. YORKS, UK
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Posts: 6636
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Re: The Case For(Or Against) Armoured Flight Decks in WW2
Posted on: 9/30/2017 9:56:25 AM
Thank you for your interest Dave-here's the full gen

Comparison is often made between the carrier designs of the Royal Navy (RN) and the United States Navy (USN). The two navies followed differing philosophies in the use of armour on carrier flight decks, starting with the design of the RN's Illustrious class and ending with the design of the Midway class, when the USN also adopted armoured flight decks.

The two classes most easily compared are the RN's Illustrious class and Implacable class and their nearest USN contemporaries, the Yorktown and Essex classes. The Illustrious class followed the Yorktown but preceded the Essex, while the Implacable-class design predated the Essex but these ships were completed after the lead ships of the Essex class.

The development of armoured flight deck carriers proceeded during World War II, and before the end of World War II both the USN, with USS Midway, and the Imperial Japanese Navy (IJN), with Taihō and Shinano would also commission armoured flight deck carriers. All USN fleet aircraft carriers built since 1945 feature armoured flight decks.

Regards

Jim
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Pro Patria Saepe Pro Rege Semper

Killroy63
Pinson, AL, USA
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Re: The Case For(Or Against) Armoured Flight Decks in WW2
Posted on: 1/11/2018 6:46:22 PM
I'm in the process of re-reading a book on the USS Enterprise, and the author mentions that armored flight decks were considered in more than one of the circa-1932 proposals for carrier design.

What militated against the inclusion of an armored decks seemed to be concerns that the carrier would prove to be top heavy and less seaworthy and that it would negatively impact the number of aircraft that the carrier could operate.

According to "The Illustrated Directory of Warships (David Miller)", the Yorktown-class could carry almost 100 aircraft on 25,500 tons. By comparison, the British carrier HMS Implacable, built some 7 years after Yorktown and weighing about 23,500 tons, could operate only 60 aircraft (and British carriers built contemporaneously with Yorktown like Ark Royal, only 60). I understand that, in both instances, some of those aircraft would be considered "spares" and thus perhaps not readily available, but the edge would still lie heavily with the American carriers.

I wish I could remember the book in which I read this anecdote because I'd love to give the writer credit, but I recall reading that one of the British carriers (Illustrious, perhaps) took a kamikaze hit off Okinawa. Whereas such a hit on the flight deck of an American carrier could have meant retirement to Ulithi (at best) or maybe even the West Coast of the US for months of repairs, the Brits merely manned brooms and swept the debris off the armored deck.

dt509er
Santa Rosa, CA, USA
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Posts: 568

Re: The Case For(Or Against) Armoured Flight Decks in WW2
Posted on: 1/14/2018 1:11:46 PM
The Brits use of steel decks absolutely paid dividends for the carriers and crews overall protection.


9 May 1945-HMS Victorious

Struck by two kamikazes. The first was a Mitsubishi A6M Zero "Zeke" making a shallow dive which hit the flight deck at Frame 30 near the forward lift (elevator), slid across the deck and into "B2" 4.5-in mount. This hit created a 25 sq. ft. hole and depressed the deck over an area of 144 sq. ft. In addition, bulkheads in the area were buckled, both "B" group 4.5" mountings were put out of action with one gun barrel destroyed, the ship's accelerator [a type of aircraft catapult] was broken and small fires were started.2 The second kamikaze hit a glancing blow against the port side aft, destroying four Corsairs and a 40 mm gun director. This hit also put an arrestor unit out of action. The two attacks killed four, seriously wounded four more and less-seriously wounded an additional twenty. Victorious was able to fly off planes one hour later and could land planes twelve hours later. Fully back in action after two days. Repairs took one month.


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Mike Johnson
Stafford, VA, USA
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Re: The Case For(Or Against) Armoured Flight Decks in WW2
Posted on: 1/14/2018 5:35:03 PM

Quote:
Jim,

The problem with the RN following the Washington Naval Treaty, is the Kreigsmarine, & the IJN sure as hell didn't!!!!!!!

MD
--Michigan Dave


Dave, Japan signed the Washington Naval Treaty. The German Navy was already much more restricted in size from the Versailles Treaty.

Mike Johnson
Stafford, VA, USA
top 20
E-7 Sgt First Class


Posts: 503

Re: The Case For(Or Against) Armoured Flight Decks in WW2
Posted on: 1/14/2018 5:36:30 PM

Quote:
If the USN had built with metal decks would we have been short a carrier at Midway?
--OpanaPointer


Why? Maybe both Lexington and Yorktown, veterans of Coral Seam would have been there and not just Yorktown

Michigan Dave
Muskegon, Michigan, MI, USA
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Posts: 3550

Re: The Case For(Or Against) Armoured Flight Decks in WW2
Posted on: 1/15/2018 9:48:57 AM
Hi Mike,

Thanks your right, both Japan & Germany were restricted in Navy size by different treaties, I forgot about that!?

But didn't Germany go over their limits anyway??

Regards, & Thanks again,
Dave
---------------
"The brave men, living and dead, who struggled here, have consecrated it, far above our poor power to add or detract."

Killroy63
Pinson, AL, USA
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Re: The Case For(Or Against) Armoured Flight Decks in WW2
Posted on: 2/20/2018 7:21:43 PM

Quote:
Hi Mike,

Thanks your right, both Japan & Germany were restricted in Navy size by different treaties, I forgot about that!?

But didn't Germany go over their limits anyway??

Regards, & Thanks again,
Dave
--Michigan Dave


Pretty much all the countries who signed the Washington Treaties cheated, at least a little bit, though none more egregiously than Germany.

Their so-called "pocket battleships" were armed with 6 11" guns and had a speed of well over 25 knots all on a displacement of 10,000 tons (under the first Treaty, any ship over 10,000 tons was considered a "capital" ship and capital ship tonnage tonnage was strictly limited). In point of fact, ships like the Graf Spee actually displaced around 14,000 tons, which meant a 40% "cheat".

The British probably most closely adhered to the terms of the treaty, to their eventual detriment. They were allowed to build two Nelson-class battleships which were very well armed (9x16" main guns) and armored, but comparatively slow (abt 23 kts). Even once they laid down their next generation of battleships, the King George V were undergunned (10 x 14" when other navies had move up to 15", 16" or even 18.1"), but they did come very close to staying within the maximum individual ship tonnage of 35,000 tons (I think they displaced about 38,000 for a less than 10% "cheat").

Japan singed the first Treaty (in 1925 I want to say), but did not sign the following treaties, which left them in a position to legally build the 70,000 ton Yamato class, armed with 9 x 18.1" guns. While it was legal, it proved to be a waste of resources. Thank Providence for small favors.

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