Comments on WWII carrier design

[William Clodius]

The following is my response to the Quora question: Why did American
Aircraft Carriers have wooden decks that were vulnerable to Kamikaze
attacks during the latter part of WWII? I thought it might be of
interest to this newsgroup, and that members might provide
corrections/additions.

Your question is most clearly posed as "Why did the newer US fleet
aircraft carriers place their armor on the hangar deck as the British
carriers proved less vulnerable to kamikazes due to their placement of
armor on the flight deck?" Your question focuses on one feature, and I
will answer your question as posed, but a less focussed question might
have surprising answers.

Every weapon is a compromise and that includes an aircraft carrier.
There were some features of carrier design that were more important to
the USN than the RN. Providing those features made the weight of an
armored flight deck much more expensive in time and material. Having
decided that those features were more important than an armored flight
deck, and that, with the advent of war, they could not afford to provide
both, they continued with a wooden flight deck on top of metal surface
as the best lightweight deck. But that does not imply that they thought
a wooden deck was better than an armored deck. It is tempting to
overgeneralize and note one major feature difference and then attribute
all other differences in combat to that one feature. The differences can
also depend on other aspects of the ship's design, the Navy's strategy,
tactics, training, and operational situation, and the corresponding
weapons, strategy, tactics, training, and operational situation of the
enemy.

The armored flight deck provided significantly more protection than the
hangar deck against one weapon, kamikazes, that was not anticipated at
the start of the war. It is not clear that it provided significantly
improved protection against other weapons. The USN placement of the
armor on the hangar deck resulted in a flight deck as superstructure,
that in turn facilitated the incorporation of other features, an open
hangar in particular, that the USN considered very useful.

The decision to not use flight deck armor was a conscious decision. At
various times they considered an armored flight deck during the design
of the Essex class. They continued to maintain this decision even though
during the later stages of the Essex design, the US had experience with
British carrier design as they were being repaired in the US naval
yards. They also considered adding flight deck armor to an open hangar
design, but thought the design work would entail much more delay then
they could tolerate. (Note at war's end the Navy fielded an open hangar
design with an armored flight deck, the Midway class, but were generally
unhappy with the result. With an open hangar the flight deck was super
structure, which increases the weight cost of the armor, and, largely as
a result, the open hangar deck was closer to the sea surface and much
wetter than earlier designs.) It is useful to examine the advantages and
disadvantages of a superstructure flight deck, and what were other
relative advantages and disadvantages of the British and US late war
carrier designs.

The advantage of the flight deck as superstructure is that it made it
easier to add some features without complicating the structural
integrity of the ship, so those features could be added at a lower cost
in design and construction. The main feature it added was an open
hangar, a feature that required the flight deck to be superstructure:
Opening the hangar walls allowed:
Cooler and less stressful operations in the tropics, subtropics,
and mid-latitude summers;
Venting of fumes allowing warmup of aircraft in the hanger so
they could be more rapidly deployed on deck;
Loading and unloading directly into the hangar while in port
speeding port operations;
Fumes from ruptures of avgas lines could be quickly vented so
fume detonations resulting from an attack were minimized;
Detonations in the hangar would vent out the sides without
putting stresses on the structure;
Dumping of aircraft and munitions over the side should a fire
start in the hangar; and
Firefighting equipment from other ships to intervene in a fire
in the hangar.
The flight deck superstructure facilitated the use of a deck edge
elevator to improve between deck operations as it:
Provided an additional lift to move aircraft between decks;
Allowed the movement of air craft between decks without
interfering with flight operations; and
Allowed the movement of aircraft without creating an opening
between decks to be exploited by the enemy.
The flight deck as superstructure also made it easier to:
Increase the size of center line aircraft elevators in upgrades;
and
Place the aircraft catapults indented below the flight deck so
they would not interfere with normal flight operations.
The placement of armor at a lower level meant that design did not
start off relatively top heavy allowing:
Wood to be used extensively on the flight deck to provide good
traction and a surface solid enough to cause most armor piercing and
semi-armor piercing weapons to pre-detonate;
The beam to be narrow enough to pass through the Panama Canal;
and
Hangars ceilings to be relatively high to store parts and accept
later larger aircraft.

The British use of the flight deck as a strength deck facilitated
the following:
It reduced the overall weight of the ship structure facilitating
the addition of other features;
This was primarily used to armor the hangar walls and that
portion of the flight deck over the hangar so that for attacks to affect
the hangar they had to use heavy cased weapons or exploit an open
elevator/lift aperture;
They also used the weight savings to add more extensive fire
prevention measures in the hangar that sometimes required manual
disabling interfering with efficient operations;
The closed hangar could more be easily kept warm for operations
in the Arctic, North Atlantic, and mid-latitude winters; and
The closed hangar made operations less susceptible to wet
conditions from high seas, a notorious problem in the North Atlantic.

In summary, compared to the British the USN choices resulted in more
flexibility and efficient operations, particularly in the Tropics, and
made a fire or bomb detonation in the hangar less likely to affect the
ship structure, but made it easier for an attack that results in a fire
or bomb detonation in the hangar. In some ways the Japanese chose the
most dangerous combination for some of their carriers as their closed
hangers with minimal armor were easily penetrated and trapped fumes with
resulting devastating losses.

The USN emphasis on flexibility and efficiency extended to other aspects
of the ship design and operation: an emphasis on maintaining crew health
through a more extensive use of air conditioning and refrigerated food;
larger crews that were less likely to have to work through exhaustion;
quarters reflecting the larger crews and reportedly more comfortable
allowing more rest; the best ship engines of the war so they were less
likely to have to leave station for fuel or maintenance; the best at sea
refueling and replenishment methods; higher hangers so reserves could be
hung from the ceiling and larger aircraft could be accepted unmodified;
larger fuel bunkerage so they could operate at longer ranges, stay on
station longer, or engage in more extended air operations; larger avgas
bunkerage so they have more sorties; and I suspect larger ship magazines
(I have trouble finding numbers for the later British carriers'
magazines). It is often noted that the USN increased its air complements
by flight deck parks, and assumed that the late war increased British
flight deck parks were comparable in effect. But with its proportionally
smaller crew quarters, fuel bunkerage, avgas bunkerage, and, probably
magazines, it was more difficult for the British to efficiently use the
larger deck parks. Probably as a result Admiral Vian was critical of
British carrier efficiency on his return to the admiralty after serving
as chief of air operations for the British Pacific Fleet.

If the USN had decided on a closed hangar and an armored flight deck
while maintaining their other design requirements, the results would
have been a longer design time, a larger ship unlikely to use the Panama
Canal, a corresponding longer construction time, more competition for
armor with cruisers and battleships, and a corresponding delay in the
return to carrier operations. As a consequence there would have been a
fuller Japanese recovery from earlier combat with more fully developed
land fortifications, and other aspects of the American advance would
almost certainly been more costly.

The USN considered their choices acceptable because:

Efficient operations could allow them to attack an enemy's carriers and
fleet before they could stage a response, and hence avoid or limit the
enemy's attack. They achieved this at Midway.
They considered the enemy's torpedoes to be the biggest threat, not
their bombs. The only fleet carriers (not light or escort) lost solely
to bomb attacks were the Japanese carriers at Midway. The US, Britain,
and Japan all lost carriers to torpedoes. Deck armor was useless against
torpedoes. The first line of defense against an enemy's submarines was
to spot them on the surface. The first line of defense against an
enemy's torpedo planes was to take out their carriers or airfields with
their attack aircraft, and the second line of defense was to take out
the aircraft with fighters before they could launch their torpedoes.
They achieved this in the Battle of Philippines Sea.
They were concerned about the rest of their forces and not just their
carriers. The more aircraft they can maintain and field in operations
the more the carriers can defend the rest of the fleet, and support
their ground forces. As bad as their carrier casualties were at Okinawa,
the losses among the lesser ships were worse, and the losses to the
ground forces were (slightly) worse than the combined casualties on all
the Navy's ships.
As a result once the USN resumed carrier operations in August 1943 with
improved AAA, radar, gun controllers, and torpedoes, the new
Independence and Essex carriers, an improved ring defense, the new F4F,
F4U, and TBF Avenger aircraft, and improved airborne torpedo tactics the
USN was largely invincible against the 3rd largest navy in the world,
and against any Japanese air force that allowed its attack pilots to
even think survival was a consideration. At Rabaul, Truk, Philippines
Sea, Southeast Asia, Formosa, and Leyte Gulf the USNAF was devastating.

Note also that the Japanese had some responses to an armored flight
deck. Earlier in the war they could have placed more emphasis on heavier
armor piercing or semi armor piercing bombs, and either developed
aircraft with greater range, or accepted closer range combat. They could
have more deliberately targeted non-carriers. They could have trained
the kamikaze pilots to target ship hulls rather than decks, modifying
the bombs to be more torpedolike.

[Geoffrey Sinclair]

Post by William Clodius
The following is my response to the Quora question: Why did American
Aircraft Carriers have wooden decks that were vulnerable to Kamikaze
attacks during the latter part of WWII? I thought it might be of
interest to this newsgroup, and that members might provide
corrections/additions.
Your question is most clearly posed as "Why did the newer US fleet
aircraft carriers place their armor on the hangar deck as the British
carriers proved less vulnerable to kamikazes due to their placement of
armor on the flight deck?" Your question focuses on one feature, and I
will answer your question as posed, but a less focussed question might
have surprising answers.
Every weapon is a compromise and that includes an aircraft carrier.
There were some features of carrier design that were more important to
the USN than the RN. Providing those features made the weight of an
armored flight deck much more expensive in time and material.

The first point I would make is the British always considered the
hangars to be magazines, with the appropriate fire fighting systems,
like salt water sprays and ventilation. Similar for aviation fuel storage,
the British carried less but with better protection. The idea of a closed
hangar helped keep aviation fuel vapours out of the rest of the ship.

Up to Ark Royal the hangars were superstructure, the first 3 Illustrious
class had a 3 inch flight deck (1 inch outside hangar) and 4.5 inch hangar
sides, the hangar deck had 3 inches between the hangar wall and the
ship's side. The second 3 Illustrious class cut the side armour to 1.5
inches to allow for a double story hangar.

Note 4.5 inch side protection was better than any RN light cruiser
except the Southampton class, which also had 4.5 inches. So the
Illustrious class were armoured hangar carriers, not just the flight deck.

The Midway class had an armoured flight deck over an open hangar.

The support carrier Unicorn, also under construction in 1939 reverted
to the hangar as superstructure, at 16,500 tons it was around two thirds
the size of the first four Illustrious class.

The Lexington and Saratoga, along with all WWII US built escort carriers
used closed hangars.

Next comes the concept of the strength deck, the physically strongest
deck on the ship. The best place to put deck armour. In the Illustrious
class, and modern US carriers, it was/is the flight deck, versus the
hangar deck in other designs. Consider how heavy modern aircraft
are versus the WWII types and how the flight deck strength now required
is defacto armouring.

Post by William Clodius
Having
decided that those features were more important than an armored flight
deck, and that, with the advent of war, they could not afford to provide
both, they continued with a wooden flight deck on top of metal surface
as the best lightweight deck.

Yes, Hornet was a repeat Yorktown as it was judged the delay in
preparing a new design was unacceptable. The design of the Essex
class started in 1939 just late enough to use the experience gained
in the Yorktown class.

Post by William Clodius
But that does not imply that they thought
a wooden deck was better than an armored deck. It is tempting to
overgeneralize and note one major feature difference and then attribute
all other differences in combat to that one feature. The differences can
also depend on other aspects of the ship's design, the Navy's strategy,
tactics, training, and operational situation, and the corresponding
weapons, strategy, tactics, training, and operational situation of the
enemy.

There were profound differences between the pre war USN and RN,
starting with the RN preference for torpedo bombers, versus the USN
dive bombers. Add the USN was prepared to use the flight deck as
an aircraft part, the RN carried only what fitted into the hangars. The
RN had the first carrier built as such, the Hermes, but otherwise had
conversions until Ark Royal. The USN had 3 conversions then 5 new
ships.

In both cases the pre war treaties limited the individual size and total
tonnage of aircraft carriers. Hence the size of Wasp. The USN also
had more time to create new designs in the late 1930's.

The RN operated on the basis of clearing the flight deck before trying
to land the next aircraft. This improved safety versus a crash barrier,
but slowed operations. The use of the crash barrier in Ark Royal did
concern the pilots.

Overall the USN evolved better flight operations, helped by the open
hangars allowing engine warm ups before ranging on the flight deck.
Something that was still clear in 1944.

As aircraft grew in size and so take off distances it became necessary
to reduce the number ranged behind the strike leader on the flight
deck, pre warming and rapid elevator times helped reduce the effect.

Also note everyone understood carriers were about the most vulnerable
warships for their size, given the aviation fuel and the normal presence
of armed and fuelled aircraft on board. Especially if any were in the
hangar. As aircraft speeds increased in the 1920's and 1930's the
chance of intercepting strikes went down and the number of fighters
carried relative to the strike and scout aircraft declined, this reversed
with radar and then the fighter bomber.

Until the Essex class the US carrier armouring schemes were about
defeating shell fire, as the limited performance of the aircraft carried
meant the carrier would need to operate close to the battle fleet but
do high speed runs away from it, risking contact with hostile surface
ships.

Post by William Clodius
The armored flight deck provided significantly more protection than the
hangar deck against one weapon, kamikazes, that was not anticipated at
the start of the war. It is not clear that it provided significantly
improved protection against other weapons.

Actually as noted in the design of the Midway the armoured flight
deck provided protection for bombs, including the fact requiring
heavier bombs to punch through the armour meant fewer could be
carried by the attacking force, reducing the chances of hits. Then
of hits making it beyond the deck.

See for example how many bombs Illustrious was hit with both at
sea then while under repair at Malta and what they did to the ship.

Post by William Clodius
The USN placement of the
armor on the hangar deck resulted in a flight deck as superstructure,
that in turn facilitated the incorporation of other features, an open
hangar in particular, that the USN considered very useful.
The decision to not use flight deck armor was a conscious decision. At
various times they considered an armored flight deck during the design
of the Essex class. They continued to maintain this decision even though
during the later stages of the Essex design, the US had experience with
British carrier design as they were being repaired in the US naval
yards.

To essentially operate as many modern aircraft as a Yorktown could
operate early/mid 1930's designs, along with improved safety features
like alternating engine and boiler rooms the Essex design grew from
around 20,000 to 27,000 tons during 1939 and 1940. Ironically none
of the aircraft designs used to calculate the size of the Essex ended
up in production. The ones that did arrive were bigger and heavier.

While the USN did look at armouring the flight deck and noted the
cost it also understood an armoured flight deck did not protect
against shellfire. You needed the deck armour to meet the belt
armour, so you would need a second armoured deck, at its most
extreme the armour could cost two thirds the air group, the Illustrious
class cost about half the air group The Essex was designed with
protection against 6 inch guns. Note there was still a gap between
the top of the belt armour and the hangar deck, allowing shells to
penetrate, the hangar deck armour was about stopping bombs
going further into the ship.

As early as 1939 the USN were generally aware of the RN ideas,
however the Essex design was completed and ships laid down before
the USN saw an Illustrious class for itself.

Post by William Clodius
They also considered adding flight deck armor to an open hangar
design, but thought the design work would entail much more delay then
they could tolerate. (Note at war's end the Navy fielded an open hangar
design with an armored flight deck, the Midway class, but were generally
unhappy with the result. With an open hangar the flight deck was super
structure, which increases the weight cost of the armor, and, largely as
a result, the open hangar deck was closer to the sea surface and much
wetter than earlier designs.) It is useful to examine the advantages and
disadvantages of a superstructure flight deck, and what were other
relative advantages and disadvantages of the British and US late war
carrier designs.

Actually it was the overall cost of flight deck armour, along with its
inability to contribute to shell fire protection that decided the issue of
the Essex class.

Midway was designed on the clear understanding the chances of
encounters with hostile surface forces had reduced to near zero.

Post by William Clodius
The advantage of the flight deck as superstructure is that it made it
easier to add some features without complicating the structural
integrity of the ship, so those features could be added at a lower cost
in design and construction. The main feature it added was an open
Cooler and less stressful operations in the tropics, subtropics,
and mid-latitude summers;
Venting of fumes allowing warmup of aircraft in the hanger so
they could be more rapidly deployed on deck;
Loading and unloading directly into the hangar while in port
speeding port operations;
Fumes from ruptures of avgas lines could be quickly vented so
fume detonations resulting from an attack were minimized;
Detonations in the hangar would vent out the sides without
putting stresses on the structure;

There were 2 survivors from the men on the Franklin's hangar deck
when it was hit.

Post by William Clodius
Dumping of aircraft and munitions over the side should a fire
start in the hangar; and
Firefighting equipment from other ships to intervene in a fire
in the hangar.
The flight deck superstructure facilitated the use of a deck edge
Provided an additional lift to move aircraft between decks;

Add no loss of hangar space to the lift well.

Post by William Clodius
Allowed the movement of air craft between decks without
interfering with flight operations; and
Allowed the movement of aircraft without creating an opening
between decks to be exploited by the enemy.

Given the elevators were as lightly built as the flight deck this
is not a real issue.

Post by William Clodius
Increase the size of center line aircraft elevators in upgrades;
and
Place the aircraft catapults indented below the flight deck so
they would not interfere with normal flight operations.
The placement of armor at a lower level meant that design did not
Wood to be used extensively on the flight deck to provide good
traction and a surface solid enough to cause most armor piercing and
semi-armor piercing weapons to pre-detonate;
The beam to be narrow enough to pass through the Panama Canal;

The smaller armoured ship would have less beam. Remember they
were designing to reasonably fixed tonnages, that is no one said
something like 5 squadrons of aircraft, full armour, it was more full
armour how many aircraft?

Post by William Clodius
and
Hangars ceilings to be relatively high to store parts and accept
later larger aircraft.

That is a design issue starting with Lexington, not an armouring issue.
The USN liked to carry sizeable spares hung from the hangar roof,
that gave the hangar height needed for later, larger designs. Though
elevator sizes were another limit, the SB2C Helldiver had problems
thanks to it needing to fit the standard elevators.

Post by William Clodius
The British use of the flight deck as a strength deck facilitated
It reduced the overall weight of the ship structure facilitating
the addition of other features;
This was primarily used to armor the hangar walls and that
portion of the flight deck over the hangar so that for attacks to affect
the hangar they had to use heavy cased weapons or exploit an open
elevator/lift aperture;
They also used the weight savings to add more extensive fire
prevention measures in the hangar that sometimes required manual
disabling interfering with efficient operations;

What exactly are you thinking of here? By treating the hangar deck
as a magazine it automatically invoked strong fire protections, more
than the USN carriers had on that deck.

Post by William Clodius
The closed hangar could more be easily kept warm for operations
in the Arctic, North Atlantic, and mid-latitude winters; and
The closed hangar made operations less susceptible to wet
conditions from high seas, a notorious problem in the North Atlantic.

See for example the weather Ark Royal was operating in when
attacking Bismarck.

Post by William Clodius
In summary, compared to the British the USN choices resulted in more
flexibility and efficient operations, particularly in the Tropics, and
made a fire or bomb detonation in the hangar less likely to affect the
ship structure, but made it easier for an attack that results in a fire
or bomb detonation in the hangar. In some ways the Japanese chose the
most dangerous combination for some of their carriers as their closed
hangers with minimal armor were easily penetrated and trapped fumes with
resulting devastating losses.

The problem with fumes is whether they could leak from the hangar or
damaged fuel tanks and make it to the rest of the ship, for example
Lexington. Open hangars made it easier for fumes to leak, open
hangars encouraged the presence of armed and fuelled aircraft, along
with doctrine.

Post by William Clodius
The USN emphasis on flexibility and efficiency extended to other aspects
of the ship design and operation: an emphasis on maintaining crew health
through a more extensive use of air conditioning and refrigerated food;

The flight ready rooms were air conditioned, not the ship, that only
happened post war. The food arrangements on the USN ships were
generally better, they were more modern and benefitted from the new
CFC refrigeration gasses, the earlier gasses were flammable or toxic
or both, not what you wanted in warship.

Post by William Clodius
larger crews that were less likely to have to work through exhaustion;
quarters reflecting the larger crews and reportedly more comfortable
allowing more rest;

Interesting idea, an early Illustrious class had around 1,500 people on
board on 23,000 tons, 747 times 95 foot flight deck, the Essex had
around twice as many people on 27,000 tons, 862 times 108 foot flight
deck. By the looks of things the RN had around 11 men per aircraft in
the airgroup, then add the ship's complement.

The rest issue was partly solved by the creation of night operations
carriers, allowing definite periods where there were no flight
operations with associated noise.

Post by William Clodius
the best ship engines of the war so they were less
likely to have to leave station for fuel or maintenance;

Please note the problems with the North Carolina and Atlanta classes,
the vibration problems were still being investigated well into the war.

Post by William Clodius
the best at sea
refueling and replenishment methods;

In theory this negated the need for large reserves on the warships.

Post by William Clodius
higher hangers so reserves could be
hung from the ceiling and larger aircraft could be accepted unmodified;

As the aircraft grew in size the spaces allowed for spares had to be
reduced, it traded off numbers for duration, fewer spares, note also the
USN populated the gallery deck, below the flight deck, as space became
an issue.

Post by William Clodius
larger fuel bunkerage so they could operate at longer ranges, stay on
station longer, or engage in more extended air operations; larger avgas
bunkerage so they have more sorties; and I suspect larger ship magazines
(I have trouble finding numbers for the later British carriers'
magazines).

Correct, the USN designed the ships for more aircraft and more
operations between port visits.

Note the Essex class had its aviation fuel storage reduced in the
second group, to increase protection. The simplest way to think
of the RN versus US and even IJN aircraft carrier design it to note
no RN carrier burned after being hit, either by torpedoes or bombs,
the Lexington and Wasp burned after their fuel tanks were ruptured
by torpedoes.

Also compare the death tolls from hits on RN versus USN carriers,
the RN was consistently smaller. Including for Kamikaze hits, for
example,

Bunker Hill 404 killed or missing when hit by a Kamikaze.

Essen 15 killed on 25 November 1944 Kamikaze hit.

Wasp 101 killed when hit by a bomb 19 March 1945, it
penetrated to number 3 deck. Franklin 724 killed or missing.

Illustrious 83 killed when bombed in January 1941.

Post by William Clodius
It is often noted that the USN increased its air complements
by flight deck parks, and assumed that the late war increased British
flight deck parks were comparable in effect. But with its proportionally
smaller crew quarters, fuel bunkerage, avgas bunkerage, and, probably
magazines, it was more difficult for the British to efficiently use the
larger deck parks. Probably as a result Admiral Vian was critical of
British carrier efficiency on his return to the admiralty after serving
as chief of air operations for the British Pacific Fleet.

Essentially the US designed with the assumption they would leave
part of the airgroup outside the hangar, the RN could do the parking
but the design limitations on fuel and ammunition carried could not
be changed in any meaningful way. So more aircraft but the same
number of sorties before replenishment.

Post by William Clodius
If the USN had decided on a closed hangar and an armored flight deck
while maintaining their other design requirements, the results would
have been a longer design time, a larger ship unlikely to use the Panama
Canal, a corresponding longer construction time, more competition for
armor with cruisers and battleships, and a corresponding delay in the
return to carrier operations. As a consequence there would have been a
fuller Japanese recovery from earlier combat with more fully developed
land fortifications, and other aspects of the American advance would
almost certainly been more costly.

There is little indication coming up with an armoured Essex class would
have been any longer than the actual design. And the ship would have
been kept to the Panama Canal limit. The decision to use more armour
would have pushed costs up yet at the same time the original plan was
to have Essex commission in 1944, not the last day in 1942. Carriers
were given number one priority which meant they had few delays in
their construction. It seems unlikely the Tarawa operation would have
been delayed because the Essex class carried heavier armour, though
clearly the fact they were carrying fewer aircraft would have an impact.
Until then the allied operations were largely using land based air power.
Note the big gap in carrier battles between 1942 and 1944.

Post by William Clodius
Efficient operations could allow them to attack an enemy's carriers and
fleet before they could stage a response, and hence avoid or limit the
enemy's attack. They achieved this at Midway.

While the idea is correct, Midway was the triumph of code breaking
coupled with long range non carrier scouting forces.

Post by William Clodius
They considered the enemy's torpedoes to be the biggest threat, not
their bombs. The only fleet carriers (not light or escort) lost solely
to bomb attacks were the Japanese carriers at Midway.

Yes, at the same time the IJN's ability to put bombs on carriers
rapidly declined in the 1942/43 period and the USN used radar
to reduce the chances of armed and fuelled aircraft being present
during air attacks.

Also note while Franklin and Bunker Hill were not sunk they were
not commissioned again. Bunker Hill was surprised, not at
action stations.

Post by William Clodius
The US, Britain,
and Japan all lost carriers to torpedoes. Deck armor was useless against
torpedoes.

So were all those AA guns and fighters. Different threats had
different defences, if you removed the in built anti torpedo
systems that would free up space for other uses.

Post by William Clodius
The first line of defense against an enemy's submarines was
to spot them on the surface.

I would add periscope depth.

Post by William Clodius
The first line of defense against an
enemy's torpedo planes was to take out their carriers or airfields with
their attack aircraft, and the second line of defense was to take out
the aircraft with fighters before they could launch their torpedoes.

The same applies to the bombers. Essentially at its most
extreme, no ship protection to enable maximum aircraft,
something the Ranger came close to.

Add blockading enemy ports to stop ship movements.

Post by William Clodius
They achieved this in the Battle of Philippines Sea.

This has very much to do with the IJN's failure to properly train
its aircrew, plus the USN had the numbers. The "price" for this
overwhelming defence was largely foregoing the chance of air
attack on the IJN fleet.

Post by William Clodius
They were concerned about the rest of their forces and not just their
carriers. The more aircraft they can maintain and field in operations
the more the carriers can defend the rest of the fleet, and support
their ground forces.

It should be pointed out with a single runway and restrictions on
landing operations in particular there was a very real upper limit
on the number of aircraft a WWII carrier could operate. The
Midways were too big, conversely by the end of WWII the Essex
were becoming too small, they were over crowded and had lost
reserve stability, making any torpedo hit more dangerous.

Note the big weight gains when Enterprise was refitted in 1943.

Post by William Clodius
As bad as their carrier casualties were at Okinawa,
the losses among the lesser ships were worse, and the losses to the
ground forces were (slightly) worse than the combined casualties on all
the Navy's ships.

The carriers were the best protected ships, that is they were usually
at the centre of the fleet.

Allied ship losses at Okinawa, all types, all causes were 371 damaged,
164 by Kamikaze, 36 sunk, 27 by kamikaze. 13 of the damaged were
fleet carriers versus 16 battleships.

Tenth army is reported to have 7,032 fatalities, the USN 4,907, the
RN 85 (41 aircrew),

Post by William Clodius
As a result once the USN resumed carrier operations in August 1943 with
improved AAA, radar, gun controllers, and torpedoes, the new
Independence and Essex carriers, an improved ring defense, the new F4F,
F4U, and TBF Avenger aircraft, and improved airborne torpedo tactics the
USN was largely invincible against the 3rd largest navy in the world,
and against any Japanese air force that allowed its attack pilots to
even think survival was a consideration. At Rabaul, Truk, Philippines
Sea, Southeast Asia, Formosa, and Leyte Gulf the USNAF was devastating.

This has little to do with the Essex design and much to do with the
IJN's failure to provide trained aircrew. Essentially for about a year
to maybe 18 months or so from 1943 to 1944, until the Kamikaze,
the allied ships became near immune from Japanese air attack. Not
totally, there were still the well trained IJN units

Post by William Clodius
Note also that the Japanese had some responses to an armored flight
deck. Earlier in the war they could have placed more emphasis on heavier
armor piercing or semi armor piercing bombs, and either developed
aircraft with greater range, or accepted closer range combat. They could
have more deliberately targeted non-carriers. They could have trained
the kamikaze pilots to target ship hulls rather than decks, modifying
the bombs to be more torpedolike.

The ultimate response to heavy armouring was the 12,000 pound tallboy
bomb versus Tirpitz. The IJN needed the next generation of aircraft,
able to lift the bigger ordnance with acceptable performance. The
replacement IJN dive bomber, the Yokosuka D4Y Suisei (Judy) went
for speed rather than bomb capacity, at 360 mph the fastest model
was not much slower than the Hellcat. Furthermore armouring the
flight deck accelerates the need for bigger bombs, or more bomb
weight devoted to casing, not explosive filling.

A hidden cost of small airgroups is the push towards multi role types,
hence the Fairey Barracuda, great if they work, but most end up with
compromised performance. Also note the defeats of 1940 played a
big part in the failure to modernise RN aircraft production and it took
until late 1942 for their new types, the Barracuda, Firefly and Seafire
to enter production and while the Firefly was not a good fighter
compared with the Hellcat it was probably a better performance light
bomber than the Avenger.

All the quotes are from the Norman Friedman books on
US and UK carriers.

"the Midway was the last US carrier in which the flight deck was
no more than a superstructure."

"Because US ships (Carriers) had shallower hull girders, they
suffered from higher stresses and this problem was aggravated
as ships became longer and longer. Thus the shift to a British
style hull (with integral flight deck) in the postwar ships was
almost inevitable."

The longer hull Essex class, about the clipper bow,

"proved a mixed blessing, as it caused excessive slamming
in service. After Ticonderoga buckled her hanger (strength)
deck in a postwar passage around Cape Horn the entire
class had to be strengthened."

There are always trade offs in designs and repairs can be made.
The general rule for armour is it costs more to build, limits damage
in action but ups the cost of repairs and modifications.

Geoffrey Sinclair
Remove the nb for email.

[William Clodius]

Thenks for the comments. I will consider incorporating what I can of
your ideas with attribution. It will take a while before I have a
revision with this much to digest. I will call out below only those
points in your message that I consider most important for the casual
readet, or the few disagreements or qualifications.

<snip>
The first point I would make is the British always considered the
hangars to be magazines, with the appropriate fire fighting systems,
like salt water sprays and ventilation. Similar for aviation fuel storage,
the British carried less but with better protection. The idea of a closed
hangar helped keep aviation fuel vapours out of the rest of the ship.

Yes this is an important point. I more strongly emphasize the treatment
as magazines. However while hangars may help limit propagation of fuel
vapors to the rest of the ship, I consider the isolation of fuel bukers
from shocks and isolation of the piping to be more important.

<snip>
Next comes the concept of the strength deck, the physically strongest
deck on the ship. The best place to put deck armour. In the Illustrious
class, and modern US carriers, it was/is the flight deck, versus the
hangar deck in other designs. Consider how heavy modern aircraft
are versus the WWII types and how the flight deck strength now required
is defacto armouring.

Also with the heavier weapons and larger fuel tanks of jets, further
strength to protect against accidents is useful. Of course by the end of
the war with the advent of high energy weapons such as German Frtiz-X,
Japanese Okha, and US "Tiny Tim" and Azon, the limitations of armour as
a defense against attack was also becoming obvious. The lack of
post-WW-II strikes against carriers , in a sense, also limited the
defensive usefulness of armor.

<snip>

Post by William Clodius
But that does not imply that they thought
a wooden deck was better than an armored deck. It is tempting to
overgeneralize and note one major feature difference and then attribute
all other differences in combat to that one feature. The differences can
also depend on other aspects of the ship's design, the Navy's strategy,
tactics, training, and operational situation, and the corresponding
weapons, strategy, tactics, training, and operational situation of the
enemy.

There were profound differences between the pre war USN and RN,
starting with the RN preference for torpedo bombers, versus the USN
dive bombers. Add the USN was prepared to use the flight deck as
an aircraft part, the RN carried only what fitted into the hangars. The
RN had the first carrier built as such, the Hermes, but otherwise had
conversions until Ark Royal. The USN had 3 conversions then 5 new
ships.

I assume "aircraft part" was meant to be "aircraft park". While they
took a while to use a flight deck park, even after they were using it
extensively the aircraft numbers were still typically significantly less
than the US carriers (except when using the small Seafires) although the
hangars are very comparable in size. I know there was some space lost in
their hangars from fire walls, but their numbers still seem smaller than
they could have fireelded bassed on available park space. Do you know if
the limitations we due the smaller designed crew complement, or ship
handling from additional weight of the aircraft given the high placement
of armor/AAA, or the combined effect of takeoff lengths and their
shorter flight decks?

<snip>
As aircraft grew in size and so take off distances it became necessary
to reduce the number ranged behind the strike leader on the flight
deck, pre warming and rapid elevator times helped reduce the effect.

Also, of course, catapaults helped in light winds.

<snip>

Post by William Clodius
The armored flight deck provided significantly more protection than the
hangar deck against one weapon, kamikazes, that was not anticipated at
the start of the war. It is not clear that it provided significantly
improved protection against other weapons.

Actually as noted in the design of the Midway the armoured flight
deck provided protection for bombs, including the fact requiring
heavier bombs to punch through the armour meant fewer could be
carried by the attacking force, reducing the chances of hits. Then
of hits making it beyond the deck.
See for example how many bombs Illustrious was hit with both at
sea then while under repair at Malta and what they did to the ship.

Yes I overemphasized kamikazes.

<snip>
To essentially operate as many modern aircraft as a Yorktown could
operate early/mid 1930's designs, along with improved safety features
like alternating engine and boiler rooms the Essex design grew from
around 20,000 to 27,000 tons during 1939 and 1940. Ironically none
of the aircraft designs used to calculate the size of the Essex ended
up in production. The ones that did arrive were bigger and heavier.

I suspedt this was true or close to true for most of the carrier designs
from the mid-30s on. The design time of a new class of capital ship took
a couple of years, then construction and sea trials (except for the
Essex class) took 2-3 years. Once war loomed design and testing of an
aircraft design took a couple of years, then setting up production
distribution to units, training, and fielding another year. The Ark
Royal was nortorious for being designed for 72 aircraft, but fielding
50-60. The Illustrious design started in 1936, and completed her trials
in mid-1940 fielding Swordfish, first fielded in 1936, and Fulmars,
first fielded mid-1940.

<snip>
As early as 1939 the USN were generally aware of the RN ideas,
however the Essex design was completed and ships laid down before
the USN saw an Illustrious class for itself.

You're right. The keel was laid for the Essex mid-April 1941 while the
Illustrious arrived for repairs mid-May. I remember Friedman discussing
discussions of the Illustrious, but maybe that was with repsect to the
Midway, or maybe my memory was playing tricks.

<snip>
Actually it was the overall cost of flight deck armour, along with its
inability to contribute to shell fire protection that decided the issue of
the Essex class.

This reads as more the combined cost of flight deck and hangar deck as
both would be needed with no hangar side armor.

<snip>
There were 2 survivors from the men on the Franklin's hangar deck
when it was hit.

The Franklin was a perfect storm. Late war intense operations near the
Japanese coast, with a short bow Essex. Large numbers of late war
aircraft with large fuel capacity, most fully fueld and well armed, with
"anti-ship" rockets sensitive to temperature the "Tiny Tims". Near
coast operations with radar clutter meant little warning time to shut
down fueling operations, that had proved so effective after the lessons
of the Lexington. The short bow Essexes had two limitations compared to
the long bows: smaller AAA suite so more likely to get hit (I expect
this was a minor problem), and a venitllation system that was recognized
as problematic int eh Essex sea trials and vastly improved in the long
bow.

Post by William Clodius
Dumping of aircraft and munitions over the side should a fire
start in the hangar; and
Firefighting equipment from other ships to intervene in a fire
in the hangar.
The flight deck superstructure facilitated the use of a deck edge
Provided an additional lift to move aircraft between decks;

Add no loss of hangar space to the lift well.

Good point.

Post by William Clodius
Allowed the movement of air craft between decks without
interfering with flight operations; and
Allowed the movement of aircraft without creating an opening
between decks to be exploited by the enemy.

Given the elevators were as lightly built as the flight deck this
is not a real issue.

I think I was misremebering the implications of comments to the effect
that failure of the elevator would not result in openings in the deck,
where the implication was not allowing attacks on the hangars, but
rather interference with flight operations.

Post by William Clodius
<snip>
The beam to be narrow enough to pass through the Panama Canal;

The smaller armoured ship would have less beam. Remember they
were designing to reasonably fixed tonnages, that is no one said
something like 5 squadrons of aircraft, full armour, it was more full
armour how many aircraft?

It would be a difficult tradeoff. The armour weight higher up with a
beam less than that of the British carriers would increase sensitivity
to wave action. They could compensate with a lower hangar height, or a
smaller AAA suite.

Post by William Clodius
and
Hangars ceilings to be relatively high to store parts and accept
later larger aircraft.

That is a design issue starting with Lexington, not an armouring issue.
The USN liked to carry sizeable spares hung from the hangar roof,
that gave the hangar height needed for later, larger designs. Though
elevator sizes were another limit, the SB2C Helldiver had problems
thanks to it needing to fit the standard elevators.

Hangar ceiling height is a problem with flight deck armor, in that it
affects metacentric height and hence ship sea handling. There is a
reason the British went to lower hangar ceilings. I recall the SB2C
problem being not fitting one on an elevator, but the USNAF wanting to
fit two.

<snip>

Post by William Clodius
They also used the weight savings to add more extensive fire
prevention measures in the hangar that sometimes required manual
disabling interfering with efficient operations;

What exactly are you thinking of here? By treating the hangar deck
as a magazine it automatically invoked strong fire protections, more
than the USN carriers had on that deck.

Treating it as a magazine in British terms meant, added weight from more
extensive spray systems, but also, in this case, fueling systems that
had to be manned during operations to keep the pumps operating. This
limited the time that fuel would be in trasfer from bunkerage to
aircraft, and reduced the chance that shocks would cause fuel leaks
between the bunkerage and the hangar. The US at that time could start
fueling the aircraft and go on to other operations.

Post by William Clodius
<snip>

The problem with fumes is whether they could leak from the hangar or
damaged fuel tanks and make it to the rest of the ship, for example
Lexington. Open hangars made it easier for fumes to leak, open
hangars encouraged the presence of armed and fuelled aircraft, along
with doctrine.

I suspect going into the effects of doctrine on the carrier casualties
would be difficult to do in the space I want to use. People focus on
deck armor and don't want to hear about fire prevention systems,
ventillatin systems, high activity operations, operations limiting
warning times, special weapons systems such as the "Tiny Tims", etc. I
am a "can't see the forest for the trees" man, and have my problems with
the many "can't see the trees for the forest" people.

Post by William Clodius
<snip>
the best ship engines of the war so they were less
likely to have to leave station for fuel or maintenance;

Please note the problems with the North Carolina and Atlanta classes,
the vibration problems were still being investigated well into the war.

I'll think about whether I should mention this.

Post by William Clodius
the best at sea
refueling and replenishment methods;

In theory this negated the need for large reserves on the warships.

Except off Okinaw you don't want the tanker near the main fleet
operations and you want to maintain operations as long as possible in
support of the rest of the forces.

<snip>
Also compare the death tolls from hits on RN versus USN carriers,
the RN was consistently smaller. Including for Kamikaze hits, for
example,
Bunker Hill 404 killed or missing when hit by a Kamikaze.

Two kamikazes

Essen 15 killed on 25 November 1944 Kamikaze hit.
Wasp 101 killed when hit by a bomb 19 March 1945, it
penetrated to number 3 deck. Franklin 724 killed or missing.

Both in operations just off shore to Japan limiting damage prevention
measures, both to perhaps the last effective Japanese dive bomber
attacks. The Wasp was able to resume high intensity operations for a few
more days.

<snip>

Post by William Clodius
They considered the enemy's torpedoes to be the biggest threat, not
their bombs. The only fleet carriers (not light or escort) lost solely
to bomb attacks were the Japanese carriers at Midway.

Yes, at the same time the IJN's ability to put bombs on carriers
rapidly declined in the 1942/43 period and the USN used radar
to reduce the chances of armed and fuelled aircraft being present
during air attacks.
Also note while Franklin and Bunker Hill were not sunk they were
not commissioned again. Bunker Hill was surprised, not at
action stations.

I believe Bunker Hill was commissioned just after the war as she served
in operation paper clip. While the Franklin may have had its crews at
action stations, it was also surprised with overcast skies and no radar
warning. Hanckock gave her one minutes warning that its lookouts had
observed the enemy aircraft. Only two guns got off fire, apparently only
after the plane had droped its bombs.

<https://www.ibiblio.org/hyperwar/USN/rep/WDR/WDR56/index.html>

D. Bomb Damage - 19 March 1945

Post by William Clodius
The US, Britain,
and Japan all lost carriers to torpedoes. Deck armor was useless against
torpedoes.

So were all those AA guns and fighters. Different threats had
different defences, if you removed the in built anti torpedo
systems that would free up space for other uses.

I have memories of reports of fighters targeting torpedoes after launch
and before impact, and one or two claims of success. In principle dual
purpose guns could targe torpedoes, but I have no memory of claims of
success.

Post by William Clodius
The first line of defense against an enemy's submarines was
to spot them on the surface.

I would add periscope depth.

On or near the surface.

<snip>

Post by William Clodius
They achieved this in the Battle of Philippines Sea.

This has very much to do with the IJN's failure to properly train
its aircrew, plus the USN had the numbers. The "price" for this
overwhelming defence was largely foregoing the chance of air
attack on the IJN fleet.

That price was largely the result not of success against the enemy's
aircraft, but rather Spruance's (proper) caution.

Post by William Clodius
They were concerned about the rest of their forces and not just their
carriers. The more aircraft they can maintain and field in operations
the more the carriers can defend the rest of the fleet, and support
their ground forces.

It should be pointed out with a single runway and restrictions on
landing operations in particular there was a very real upper limit
on the number of aircraft a WWII carrier could operate. The
Midways were too big, conversely by the end of WWII the Essex
were becoming too small, they were over crowded and had lost
reserve stability, making any torpedo hit more dangerous.
Note the big weight gains when Enterprise was refitted in 1943.

I wouldn't be surprised if the growth in AAA suites and aircraft that
impacted stability at least partly reflected a recognition that
torpedoes were becoming unimportant. In spite of the loss of the
Indianopolis, with the success of the battle of the Atlantic, the
devastation to the IJNAF, and the successes against the Japanese fleet
as a whole they were having much less impact on allied operations. Only
one Essex carrier, the Intepid, suffered a torpedo hit in Feb. 1944. As
it wasn't a side hit stability wasn't a problem.

<snip>
This has little to do with the Essex design and much to do with the
IJN's failure to provide trained aircrew. Essentially for about a year
to maybe 18 months or so from 1943 to 1944, until the Kamikaze,
the allied ships became near immune from Japanese air attack. Not
totally, there were still the well trained IJN units

But by the same major a major reason they needed replacement crews was
due to carrier operations in 42, although of course the marines in the
Eastern Solomons, the USAAF and AAF in New Guinea, and mosquitos and
poor sanitary conditons all contributed. And they were not jusf fighting
the IJNAF. I would have thought that the IJAAF would have had a
significant number of trained air crews at Formosa.

<snip>
The ultimate response to heavy armouring was the 12,000 pound tallboy
bomb versus Tirpitz. The IJN needed the next generation of aircraft,
able to lift the bigger ordnance with acceptable performance. The
replacement IJN dive bomber, the Yokosuka D4Y Suisei (Judy) went
for speed rather than bomb capacity, at 360 mph the fastest model
was not much slower than the Hellcat. Furthermore armouring the
flight deck accelerates the need for bigger bombs, or more bomb
weight devoted to casing, not explosive filling.

The D4Y could carry a 500 kg bomb, a weight similar to the bombs used by
the Germans against the Illustrious and Formidable. The P1Y and B7A
could carry heavier bomb, but as glide bombers the lower impact speed
would reduce penetration. I would argue that the ultimate response
against armor would have been a guided rocket. More energy in a more
compact system. The US at wars end had most of the pieces available for
such a system, having both bomb guidance systems and airborne rockets,
but little motivation at wars end. The Okha was in principle an
effective weapon, but the bomber used to deliver it was vulnerable, and
a large number were lost with the Sinano and Unryu. Tenative plans to
use them directly from land bases against the invasion Kyushuhad the
potential (if the pilots could corntol them and they could be based
close to the landings) of causing great dam

[William Clodius]

William Clodius <***@icloud.com> wrote:
<snip>

Post by William Clodius
The US at wars end had most of the pieces available for
such a system, having both bomb guidance systems and airborne rockets,
but little motivation at wars end. The Okha was in principle an
effective weapon, but the bomber used to deliver it was vulnerable, and
a large number were lost with the Sinano and Unryu. Tenative plans to
use them directly from land bases against the invasion Kyushuhad the
potential (if the pilots could corntol them and they could be based
close to the landings) of causing great dam

Errors/typos that I want to fix:
The US at wars end had most of the pieces available for such a system,
having both bomb guidance systems and airborne rockets,
but little time to combine them during the war and little motivation at
wars end. The Okha could in principle hane been an effective weapon, but
the bomber used to deliver it was vulnerable, and a large number were
lost with the Sinano and Unryu. Tenative plans were to use them
directly from land bases against the invasion of Kyushu. If the pilots
could corntol them and they could be based close to the landings they
had the potential causing great damage in spite of their short range.

[Geoffrey Sinclair]

Post by William Clodius
Thenks for the comments. I will consider incorporating what I can of
your ideas with attribution.

Planning on a published article?

Post by William Clodius
I will call out below only those
points in your message that I consider most important for the casual
readet, or the few disagreements or qualifications.

Same in the reply.

Post by William Clodius

<snip>
The first point I would make is the British always considered the
hangars to be magazines, with the appropriate fire fighting systems,
like salt water sprays and ventilation. Similar for aviation fuel
storage, the British carried less but with better protection. The
idea of a closed
hangar helped keep aviation fuel vapours out of the rest of the ship.

Yes this is an important point. I more strongly emphasize the treatment
as magazines. However while hangars may help limit propagation of fuel
vapors to the rest of the ship, I consider the isolation of fuel bukers
from shocks and isolation of the piping to be more important.

There are the two issues. The RN stored aviation fuel in cylinders
surrounded by sea water and "separated" from the hull structure.
Much safer but at a cost of fuel capacity.

Then comes the size of the pipelines, again as far as I know the
RN used smaller sizes so a rupture was less of an issue but at
the cost of refueling times.

Next comes the enclosed hangar and associated ventilation which
normally prevented any fuel spills entering the rest of the ship. RN
officers noted how it was usual for a USN carrier to smell of fuel.

Essentially from start to finish the RN designs were prepared to
build in more safety in handling aircraft, their ordnance and their
fuel. At a cost in operational tempo and amount of replenishment
required.

Illustrious could stow 45 torpedoes, 100x500 pound, 550x250 pound,
200x250 pound AP, 400x100 pound and 600x20 pound bombs.

Post by William Clodius

<snip>
Next comes the concept of the strength deck, the physically strongest
deck on the ship. The best place to put deck armour. In the Illustrious
class, and modern US carriers, it was/is the flight deck, versus the
hangar deck in other designs. Consider how heavy modern aircraft
are versus the WWII types and how the flight deck strength now required
is defacto armouring.

Also with the heavier weapons and larger fuel tanks of jets, further
strength to protect against accidents is useful.

First the correction, Ark Royal introduced the flight deck as the main,
strength, deck. According to the book Nelson to Vanguard the
technique actually saved on hull weight, pushing 1,000 tons compared
with Yorktown. I am not sure I believe the following table though, given
things like the different definitions of things like hull weights. Table is
Yorktown / Ark Royal

19,900 / 22,000 Standard displacement in tons
63 / 54 aircraft operated
781 / 720 length of flight deck in feet
14,451 / 13,651 Hull and fittings in tons
186,680 / 120,090 avgas capacity US gallons.

H T Lenton gives the waterline length of Ark Royal as 721.5 feet,
flight deck 797 feet, and it looks like the above length is also
waterline for Yorktown.

Norman Friedman gives the 1938 Enterprise as hull and fittings
14,451 tons, standard displacement 19,576, flight deck 802 feet,
and 80 to 90 aircraft on board. Friedman notes essentially the
US aircraft complement depended on how much of the flight
deck was devoted to aircraft parking. So Lexington and
Saratoga normally operated 70 (2 small to 1 big ratio) aircraft,
could carry 110, while in the 1930 maneuvers started with 82
but by mid day were down to an effective 52 because of the
need to reserve flight deck space for take off and landings.

At Coral Sea Lexington had 71 and Yorktown 72 aircraft on board.

At Midway Yorktown had 75, Enterprise and Hornet 79 aircraft
on board. It should therefore be possible, using deck parking,
for Ark Royal to operate about the same number of aircraft as
a Yorktown. Given a Illustrious had 40 to 50 feet less flight deck
length than Ark Royal and seemed to use around 18 aircraft as
the deck park size.

Essentially the increase in aircraft weights into the modern era
forced stronger flight and hangar decks, and as noted the strength
helps contain damage. Also the modern jet fuels are much less
flammable and explosive than the WWI high octane aviation fuels.

At its most extreme the fuel for the SR-71 could have a lighted match
thrown into it and not burn.

Post by William Clodius
Of course by the end of
the war with the advent of high energy weapons such as German Frtiz-X,
Japanese Okha, and US "Tiny Tim" and Azon, the limitations of armour as
a defense against attack was also becoming obvious.

Yes, along with the reality things like radars could not be armoured
and becoming electronically deaf and blind is a major loss.

Essentially the performance of aircraft went up so much armour
as a defence became prohibitively expensive. Similar problems
with magnetic fused torpedoes.

Post by William Clodius
The lack of
post-WW-II strikes against carriers , in a sense, also limited the
defensive usefulness of armor.

The fundamental threat changed, torpedoes remain, but not air
launched, now we have missiles that tend to come in from the
side, certainly at a much shallower angle than free fall bombs.
The chance of a successful free fall bomb attack is very small
these days.

Whether anyone can generate a saturation missile attack is
also an issue. A USN carrier air group is bigger than most
country's combat air force.

Post by William Clodius

<snip>

Post by William Clodius
But that does not imply that they thought
a wooden deck was better than an armored deck. It is tempting to
overgeneralize and note one major feature difference and then attribute
all other differences in combat to that one feature. The differences can
also depend on other aspects of the ship's design, the Navy's strategy,
tactics, training, and operational situation, and the corresponding
weapons, strategy, tactics, training, and operational situation of the
enemy.

There were profound differences between the pre war USN and RN,
starting with the RN preference for torpedo bombers, versus the USN
dive bombers. Add the USN was prepared to use the flight deck as
an aircraft part, the RN carried only what fitted into the hangars. The
RN had the first carrier built as such, the Hermes, but otherwise had
conversions until Ark Royal. The USN had 3 conversions then 5 new
ships.

I assume "aircraft part" was meant to be "aircraft park".

Yes, spell checkers reach limits with correctly spelled erroneous words.

Post by William Clodius
While they
took a while to use a flight deck park, even after they were using it
extensively the aircraft numbers were still typically significantly less
than the US carriers (except when using the small Seafires) although the
hangars are very comparable in size. I know there was some space lost in
their hangars from fire walls, but their numbers still seem smaller than
they could have fireelded bassed on available park space. Do you know if
the limitations we due the smaller designed crew complement, or ship
handling from additional weight of the aircraft given the high placement
of armor/AAA, or the combined effect of takeoff lengths and their
shorter flight decks?

First point the RN spent a lot of time designing carriers to minimise
turbulence and have quotes like US carriers seemed optimised to
generate turbulence. As a result the RN carriers tended to have round
downs, non level parts of the flight deck, which limited deck parking
areas. The Illustrious class had theirs progressively removed.

However the key limits were the built in aviation fuel and aircraft
weapons magazines and as noted on board accommodation, given
each extra aircraft created the need for several more crew. In any
case while the RN carriers could carry the extra aircraft they could
not generate any more sorties between replenishments, while
creating a crowding problem for both crew and aircraft. The final 2
Illustrious class actually had full double story hangars but half the
lower hangar had to be used for crew space.

The weight distribution within the ship played no part.

Seafire III 36 feet 10 inches by 30 feet 2.5 inches, 6,200 pounds empty.
Hellcat 42 feet 10 inches by 33 feet 7 inches, 9,238 pounds empty
Corsair 41 feet by 33 feet 4 inches, 8,982 pounds empty.

Not sure it was a hangar size issue, even less so if the wings were folded,
in any case Ark Royal had bigger hangars, the Illustrious class made
the hangars small so they could be armoured, so 36 aircraft stowed,
along with a smaller flight deck, about 60 feet shorter than a Yorktown,
and over a hundred versus an Essex.

In 1945 the smaller Illustrious class had 54, the bigger 70 to 80
aircraft. The Enterprise, now displacing around the same tonnage
as the smaller Illustrious was operating up to 90 (including 36 of the
fighter size SBD) and an Essex, displacing about the same as
a larger Illustrious around 100, including 70 fighters.

Essentially the US carriers had allowed for larger airgroups and
had larger flight decks, and larger hangar sizes, at least versus the
smaller Illustrious and possibly the larger ones as well.

The Illustrious class hangar is between the two elevators, as is
Yorktown but look at where the elevators are, the Essex is from
the forward elevator to the stern

Post by William Clodius

As aircraft grew in size and so take off distances it became necessary
to reduce the number ranged behind the strike leader on the flight
deck, pre warming and rapid elevator times helped reduce the effect.

Also, of course, catapaults helped in light winds.

Yes but catapault cycle times were normally considered too slow to be
able to use them to launch strikes. The USN thought of them in terms
of avoiding respotting the flight deck for a small launch.

<snip>

Post by William Clodius

To essentially operate as many modern aircraft as a Yorktown could
operate early/mid 1930's designs, along with improved safety features
like alternating engine and boiler rooms the Essex design grew from
around 20,000 to 27,000 tons during 1939 and 1940. Ironically none
of the aircraft designs used to calculate the size of the Essex ended
up in production. The ones that did arrive were bigger and heavier.

I suspedt this was true or close to true for most of the carrier designs
from the mid-30s on.

Yes, as of 1945 the USN considered the Essex class obsolescent,
over crowded and over weight, with corresponding reductions in
ability to handle underwater damage.

Post by William Clodius
The design time of a new class of capital ship took
a couple of years, then construction and sea trials (except for the
Essex class) took 2-3 years. Once war loomed design and testing of an
aircraft design took a couple of years, then setting up production
distribution to units, training, and fielding another year. The Ark
Royal was nortorious for being designed for 72 aircraft, but fielding
50-60. The Illustrious design started in 1936, and completed her trials
in mid-1940 fielding Swordfish, first fielded in 1936, and Fulmars,
first fielded mid-1940.

Design cycles were longer for both ships and aircraft than you
indicate. Think of how many aircraft were designed and entered
mass production and combat after war was declared. Similarly,
look at the delays in the relatively minor changes in the USN
Cleveland/Fargo and Baltimore/Oregon City classes. Certainly
the design and build cycle for fleet carriers was longer than that
for their aircraft.

The USN construction program rated carriers as the number 1
priority and was prepared to pay for rapid production. The
design issue was the reason the USN ordered so many Essex,
Cleveland, Baltimore etc. classes, including the shipyards build
repeat ships more quickly.

Also the Illustrious had Fulmars and Albacores, the Swordfish
replacement, the Swordfish production line was shut down at
the end of 1939 as the Albacore took over. A year later the
Swordfish was put back into production, the Albacore stayed
in production to the end of 1942, being replaced by the
Barracuda.

The big jump in aircraft weights and performance made
carrier design a real moving target in the late 1930's and
into the 1950's with the arrival of the jets, which had the
further problem of poor acceleration from rest.

<snip>

Post by William Clodius

<snip>
Actually it was the overall cost of flight deck armour, along with its
inability to contribute to shell fire protection that decided the issue
of the Essex class.

This reads as more the combined cost of flight deck and hangar deck as
both would be needed with no hangar side armor.

As far as I can tell the thinking was the belt armour should rise to
meet the deck armour in order to keep out shells, the higher the
armoured deck the bigger the belt. Which influences where the
deck armour should be.

Post by William Clodius

There were 2 survivors from the men on the Franklin's hangar deck
when it was hit.

The Franklin was a perfect storm. Late war intense operations near the
Japanese coast, with a short bow Essex.

Not the point I was trying to make, look at the casualties when USN
aircraft carriers took hits versus those for RN carriers. The RN ships
normally took significantly fewer casualties.

Post by William Clodius
Large numbers of late war
aircraft with large fuel capacity, most fully fueld and well armed, with
"anti-ship" rockets sensitive to temperature the "Tiny Tims". Near
coast operations with radar clutter meant little warning time to shut
down fueling operations, that had proved so effective after the lessons
of the Lexington.

Simply put an unwarned carrier is about the most vulnerable
WWII warship and the more aircraft you operate the harder it
is to keep track of everything and the more likely you are to
have armed and fueled aicraft on board. Princeton is another
example.

Simply put the RN was much less likely to have the ship in a
similar state, it meant less chance of intercepting the incoming
strike but less chance of self destruction.

Post by William Clodius
The short bow Essexes had two limitations compared to
the long bows: smaller AAA suite so more likely to get hit (I expect
this was a minor problem), and a venitllation system that was recognized
as problematic int eh Essex sea trials and vastly improved in the long
bow.

While the light AA guns of the carriers were upgraded as they went
in for refits as far as I can tell the difference between the two Essex
groups was a third gunnery director and four 40mm pieces, and
that mounting was in the bows.

Ten Essex had the old ventilation, 7 of the long hull ships
were commissioned by the end of the war.

Post by William Clodius

Post by William Clodius
Allowed the movement of air craft between decks without
interfering with flight operations; and
Allowed the movement of aircraft without creating an opening
between decks to be exploited by the enemy.

Given the elevators were as lightly built as the flight deck this
is not a real issue.

I think I was misremebering the implications of comments to the effect
that failure of the elevator would not result in openings in the deck,
where the implication was not allowing attacks on the hangars, but
rather interference with flight operations.

So perhaps the idea a hit on the elevator could jam it not fully up,
or perhaps blow the platform overboard or into some sort of
state that obstructed the flight deck, versus a bomb putting a hole
in the flight deck. Another reason for deck edge elevators.

Post by William Clodius

Post by William Clodius
<snip>
The beam to be narrow enough to pass through the Panama Canal;

The smaller armoured ship would have less beam. Remember they
were designing to reasonably fixed tonnages, that is no one said
something like 5 squadrons of aircraft, full armour, it was more full
armour how many aircraft?

It would be a difficult tradeoff. The armour weight higher up with a
beam less than that of the British carriers would increase sensitivity
to wave action. They could compensate with a lower hangar height, or a
smaller AAA suite.

While the Midways were designed with relaxed Panama Canal rules
I think it still holds any armoured Essex class would stay within the
pre war canal limit while making the design decision on how much
protection and how many aircraft. Note how much AA protection
the RN designed in versus the USN.

Post by William Clodius

Post by William Clodius
and
Hangars ceilings to be relatively high to store parts and accept
later larger aircraft.

That is a design issue starting with Lexington, not an armouring issue.
The USN liked to carry sizeable spares hung from the hangar roof,
that gave the hangar height needed for later, larger designs. Though
elevator sizes were another limit, the SB2C Helldiver had problems
thanks to it needing to fit the standard elevators.

Hangar ceiling height is a problem with flight deck armor, in that it
affects metacentric height and hence ship sea handling.

As is non armoured flight deck, the higher the hangar deck the further
the flight deck from sea level. As is aircraft capacity and weight, given
they sit on the flight deck, the design requirements were pushing the
flight deck into becoming the strength deck, which is the best place to
put armour as it helps the strength.

It does require in carriers the discounting of shell fire as an obstacle,
and, in theory anyway, things like skip bombing and large rockets.

Post by William Clodius
There is a
reason the British went to lower hangar ceilings. I recall the SB2C
problem being not fitting one on an elevator, but the USNAF wanting to
fit two.

The Helldiver as far as I am aware was limited by the elevator, if fitting
two per cycle was a real issue I have not heard it.

For what it is worth the SB2C with wings folded had a height of 16
feet 10 inches, the folding operation required a clear 20 feet 6.5
inches. The F4U-1 figures were 16 feet 4.125 inches and 18 feet
1.3125 inches. Hence the clipped wings on RN Corsairs. If a
propeller blade was left vertical the SB2C height was 14 feet 9
inches with the 4 bladed propeller and 1 inch less with the 3
bladed one, the Corsair propeller height was 14 feet 8.5 inches,
with the 3 blade propeller.

As for the British hangar heights it was a design decision, best seen
in HMS Unicorn, the support carrier that became the defacto
prototype for the RN light fleet carrier program. Unicorn's hangar
height was set at 16.5 feet so it could handle all RN aircraft, including
the various seaplanes and amphibians. The Essex design called for
an 18 foot clear hangar height.

Ark Royal's hangars were 16 feet.

The first 3 Illustrious class had 16 foot hangars, the final 3 as far as
I am aware had two 14 foot hangars.

The post war Ark Royal and Eagle had 17.5 foot hangars, as did
the light fleet program.

Post by William Clodius

<snip>

Post by William Clodius
They also used the weight savings to add more extensive fire
prevention measures in the hangar that sometimes required manual
disabling interfering with efficient operations;

What exactly are you thinking of here? By treating the hangar deck
as a magazine it automatically invoked strong fire protections, more
than the USN carriers had on that deck.

Treating it as a magazine in British terms meant, added weight from more
extensive spray systems, but also, in this case, fueling systems that
had to be manned during operations to keep the pumps operating. This
limited the time that fuel would be in trasfer from bunkerage to
aircraft, and reduced the chance that shocks would cause fuel leaks
between the bunkerage and the hangar. The US at that time could start
fueling the aircraft and go on to other operations.

The shock resistance was done by separating the fuel tanks from
the hull structure, what you are describing is the British had a fuelling
system that automatically shut down unless told otherwise. Is that
what you mean? Times come down to things like pumping rates
and the number of fuel hoses available. Not something most
references give answers for. As far as I know, and in keeping with
fewer aircraft, the RN carriers had slower and fewer fuel hoses.

Post by William Clodius

Post by William Clodius
<snip>

The problem with fumes is whether they could leak from the hangar or
damaged fuel tanks and make it to the rest of the ship, for example
Lexington. Open hangars made it easier for fumes to leak, open
hangars encouraged the presence of armed and fuelled aircraft, along
with doctrine.

I suspect going into the effects of doctrine on the carrier casualties
would be difficult to do in the space I want to use. People focus on
deck armor and don't want to hear about fire prevention systems,
ventillatin systems, high activity operations, operations limiting
warning times, special weapons systems such as the "Tiny Tims", etc. I
am a "can't see the forest for the trees" man, and have my problems with
the many "can't see the trees for the forest" people.

Given how fires sank or heavily damaged carriers the fire protection
systems are important, ideally the hull/deck reject the bomb and it
explodes outside the ship, after that comes damage limitations,
further armour, compartmentalisation, redundancy, fire fighting
equipment and so on.

If the writings are correct the open hangar enabled fumes to spread
through the ship under normal operations.

My point is RN fleet carriers seem to have taken light casualties
even when heavily damaged compared with the US carriers, and
that must count for something.

Post by William Clodius

Post by William Clodius
the best at sea
refueling and replenishment methods;

In theory this negated the need for large reserves on the warships.

Except off Okinaw you don't want the tanker near the main fleet
operations and you want to maintain operations as long as possible in
support of the rest of the forces.

Yes for the tankers and not so much for the individual carrier, the
crew could not leave the ship, they needed rest days on a regular
basis to maintain efficiency.

Post by William Clodius

<snip>
Also compare the death tolls from hits on RN versus USN carriers,
the RN was consistently smaller. Including for Kamikaze hits, for
example,
Bunker Hill 404 killed or missing when hit by a Kamikaze.

Two kamikazes

Sorry, that should have been two, the first one skidded
along the flight deck before going overboard, its bomb
went through the hull and exploded just above the water,
the second one crashed on the flight deck, the bomb made
it to the gallery deck and started fires from number 2 lift
to about the stern of the ship.

Post by William Clodius

Essen 15 killed on 25 November 1944 Kamikaze hit.
Wasp 101 killed when hit by a bomb 19 March 1945, it
penetrated to number 3 deck. Franklin 724 killed or missing.

Both in operations just off shore to Japan limiting damage prevention
measures, both to perhaps the last effective Japanese dive bomber
attacks. The Wasp was able to resume high intensity operations for a few
more days.

If you are going to talk about ship design then where geographically
the damage was taken is not an issue, unless you subscribe to the
safer car idea making drives more aggressive because the car is
safer and therefore reducing or even more than negating the overall
safety increase.

No one could expect immunity from air attack, not even the western
allies in France in 1944 in daylight. The issue is the protections
built into the ship, their trade off between generating sorties and
aircraft capacity.

Post by William Clodius

<snip>

Post by William Clodius
They considered the enemy's torpedoes to be the biggest threat, not
their bombs. The only fleet carriers (not light or escort) lost solely
to bomb attacks were the Japanese carriers at Midway.

Yes, at the same time the IJN's ability to put bombs on carriers
rapidly declined in the 1942/43 period and the USN used radar
to reduce the chances of armed and fuelled aircraft being present
during air attacks.
Also note while Franklin and Bunker Hill were not sunk they were
not commissioned again. Bunker Hill was surprised, not at
action stations.

I believe Bunker Hill was commissioned just after the war as she served
in operation paper clip.

Could be, I would presume it was fully repaired before this, rather
than "good enough" for limited service.

Post by William Clodius
While the Franklin may have had its crews at
action stations, it was also surprised with overcast skies and no radar
warning. Hanckock gave her one minutes warning that its lookouts had
observed the enemy aircraft. Only two guns got off fire, apparently only
after the plane had droped its bombs.
<https://www.ibiblio.org/hyperwar/USN/rep/WDR/WDR56/index.html>
D. Bomb Damage - 19 March 1945

The point I am still trying to make is "damage resistance" is more than
the ship sinking or not. The USN decisions about where armed and
fuelled aircraft could be kept and fuel system designs ran more risks
than the RN and that seems to show up most obviously in crew casualties
when damage was taken when the ship was unwarned or hit while
carrying out operations. Along with the carriers that were sunk.

Remember even the Essex was designed without radar in mind.

Post by William Clodius

Post by William Clodius
The US, Britain,
and Japan all lost carriers to torpedoes. Deck armor was useless
against torpedoes.

So were all those AA guns and fighters. Different threats had
different defences, if you removed the in built anti torpedo
systems that would free up space for other uses.

I have memories of reports of fighters targeting torpedoes after launch
and before impact, and one or two claims of success. In principle dual
purpose guns could targe torpedoes, but I have no memory of claims of
success.

One Japanese pilot crashed into a torpedo headed for the Taiho.

Not my point. Ships carried "passive" anti torpedo systems to limit
the damage when hit, those systems had a cost. The space and
weight could be used for other things.

You seem to be finding reasons why the deck armour was not worth
it, but a lot of the differences between the RN and USN had nothing
to do with deck armour, and most of the RN aircraft operating
practice was behind the USN.

Flight deck armour made more sense as carriers grew and the
flight deck became the strength deck. What made much less
sense was side armour given the steady decrease in the chance
of being attacked by hostile surface forces. The sort of chances
that saw the USN and IJN battleship/cruiser conversions carrying
8 inch guns.

Now of course the reality is if you know the flight deck is armoured
and the sides are not you try attacking with skip bombs or rockets
or torpedoes and so on. One reason armouring was stopped is
just how much was needed to protect the whole ship from all the
threats that existed at the end of WWII.

Post by William Clodius

Post by William Clodius
They achieved this in the Battle of Philippines Sea.

This has very much to do with the IJN's failure to properly train
its aircrew, plus the USN had the numbers. The "price" for this
overwhelming defence was largely foregoing the chance of air
attack on the IJN fleet.

That price was largely the result not of success against the enemy's
aircraft, but rather Spruance's (proper) caution.

The result was the USN devoted 100% of its fighter force to
defence, and strikes would need escorts, reducing the defensive
force.

I have no problems with what Spruance did given what was
known at the time. I also know if say half the USN fighters
were away escorting strikes the amount of damage the USN
took would have gone up, even more so if the Japanese had
managed to properly train their aircrews, including better
survival against hostile interceptors.

Post by William Clodius

Post by William Clodius
They were concerned about the rest of their forces and not just their
carriers. The more aircraft they can maintain and field in operations
the more the carriers can defend the rest of the fleet, and support
their ground forces.

It should be pointed out with a single runway and restrictions on
landing operations in particular there was a very real upper limit
on the number of aircraft a WWII carrier could operate. The
Midways were too big, conversely by the end of WWII the Essex
were becoming too small, they were over crowded and had lost
reserve stability, making any torpedo hit more dangerous.
Note the big weight gains when Enterprise was refitted in 1943.

I wouldn't be surprised if the growth in AAA suites and aircraft that
impacted stability at least partly reflected a recognition that
torpedoes were becoming unimportant.

As far as I know navies still rate torpedo hits as worse than
bombs or missiles as the torpedoes open up hull breaches,
(I am ignoring magnetic exploders.)

Yorktown, Lexington, Hornet, Wasp were all hit by torpedoes,
that played a big part in the Enterprise refit and the Essex
changes in the long hull group. Along with the fact Enterprise
was being overloaded. So more and better radar, more and
better light AA, better main gun directors, old fuel tanks
replaced by saddle tanks, blistered to a new beam of 95 feet
5 inches versus 83 feet 2.5 inches as built, four new fire fighting
pumps, combined output 4,400 gallons a minute, more powerful
catapaults, 91 aircraft, 32,060 tons full load versus 25,484 as built.

By the way the larger Illustrious class were 32,100 and 32,800
tons full load as built. Essex 36,380 as designed.

Similar overloading was occurring on the Essex class, again
it is a trade off, more offensive power cutting defence.

Franklin actually "developed symptoms of critical stability
conditions due to fire fighting water". It was estimated
Franklin with one torpedo hit would list about the same
as the 1942 Essex with two torpedo hits.

Post by William Clodius
In spite of the loss of the
Indianopolis, with the success of the battle of the Atlantic, the
devastation to the IJNAF, and the successes against the Japanese fleet
as a whole they were having much less impact on allied operations.

Yes, as noted for maybe 18 months the allied shipping became
near immune from Japanese air attack, from 1943 until the
kamikazes. And yes I note Houston and Canberra etc.

Post by William Clodius
Only
one Essex carrier, the Intepid, suffered a torpedo hit in Feb. 1944. As
it wasn't a side hit stability wasn't a problem.

You would hope 1 torpedo would not sink a fleet carrier, apart
from the design flaw in Ark Royal, key personnel were evacuated
and not available to fix damage caused by the flooding.

Post by William Clodius

<snip>
This has little to do with the Essex design and much to do with the
IJN's failure to provide trained aircrew. Essentially for about a year
to maybe 18 months or so from 1943 to 1944, until the Kamikaze,
the allied ships became near immune from Japanese air attack. Not
totally, there were still the well trained IJN units

But by the same major a major reason they needed replacement crews was
due to carrier operations in 42, although of course the marines in the
Eastern Solomons, the USAAF and AAF in New Guinea, and mosquitos and
poor sanitary conditons all contributed.

I think you will find that while the carrier battles cost the Japanese
lots of aircrew it was the months of fighting that caused the most
losses. In any case you cannot design ships on the basis the
other side has ineffective weapons and so will not hit.

Post by William Clodius
And they were not jusf fighting
the IJNAF. I would have thought that the IJAAF would have had a
significant number of trained air crews at Formosa.

The IJAAF had minimal anti shipping ability and over water
navigation ability. One reason why the kamikaze operations
against an invasion of Japan would be more intense, more
aircraft, fewer navigation problems.

Post by William Clodius

<snip>
The ultimate response to heavy armouring was the 12,000 pound tallboy
bomb versus Tirpitz. The IJN needed the next generation of aircraft,
able to lift the bigger ordnance with acceptable performance. The
replacement IJN dive bomber, the Yokosuka D4Y Suisei (Judy) went
for speed rather than bomb capacity, at 360 mph the fastest model
was not much slower than the Hellcat. Furthermore armouring the
flight deck accelerates the need for bigger bombs, or more bomb
weight devoted to casing, not explosive filling.

The D4Y could carry a 500 kg bomb, a weight similar to the bombs used by
the Germans against the Illustrious and Formidable. The P1Y and B7A
could carry heavier bomb, but as glide bombers the lower impact speed
would reduce penetration.

The B7A had a whole 80 or so built from March 1944 on, and was
meant to have dive bombing capacity, 800 kg bomb load, the P1Y
was not carrier capable, 1,000 kg of bombs for the main versions,
built from 1943 on, and 1,600 kg for the 100 improved versions
built 1944/45.

The G3M went out of production in 1941, 800 kg of bombs, as could
the G4M.

The D4Y could carry a 560 kg of bombs, including as noted a 500 kg
one, normal bomb load was 310 kg. The USN equivalent was about
50 mph slower, significantly bigger and could carry 2,000 pounds of
bombs internally if they were AP. The USN performance charts have
a 3,000 pound bomb load option, top speed 257 mph, the torpedo
carrying option top speed was 251 mph (both on normal power) versus
287 mph top speed clean on normal power or 298 mph using military power.

Post by William Clodius
I would argue that the ultimate response
against armor would have been a guided rocket.

The guided rocket should up hit chances, then comes carrying a
warhead able to penetrate.

Post by William Clodius
More energy in a more
compact system. The US at wars end had most of the pieces available for
such a system, having both bomb guidance systems and airborne rockets,
but little motivation at wars end. The Okha was in principle an
effective weapon, but the bomber used to deliver it was vulnerable, and
a large number were lost with the Sinano and Unryu.

The Okha tended to be carried by the twin engined bombers.

Post by William Clodius
Tenative plans to
use them directly from land bases against the invasion Kyushuhad the
potential (if the pilots could corntol them and they could be based
close to the landings) of causing great dam

As noted you seem to have the theme the armour was wrong, but
your reasons often have nothing to do with the armour.

In WWII the aircraft could carry bombs/rockets big enough that the
amount of armour required to reject them became prohibitive,
especially deck armour. The armour could help as not all hits were
at right angles and force the other side to carry bigger, therefore
fewer bombs, but it was becoming clear hits were going to be
more destructive and more protection needed to be built in with
things like damage control resources, compartmentalisation and
so on rather than thicker armour. In addition the eyes and ears of
the fleet were now electronic and those could not be armoured.

Now more fighters and more AA guns can usually stop fewer
launches against your ship, or shoot down incoming missiles
but like the armour, they cannot guarantee immunity.

In WWII the RN had closed hangars and much more built in
protection against fire, this cost weight and aviation fuel capacity.
it also restricted the rate of RN carrier operations with things like
engine warm ups having to wait until on the flight deck, rates of
refueling being lower than the USN, add it seems the basics of
aircraft handling when they were on the ship. The gap was much
more than just the ship design.

The RN carriers came with 16 heavy AA guns with 4 directors,
and 6 light AA mountings with their own directors, Essex as
designed carried 12 heavy AA guns with 2 directors and 4 light
AA mountings (Ignoring the machine guns)

The RN also tried armoured hangars, it was not just an armoured
flight deck. That clearly sacrificed too much air capacity, so much
so that the fourth in the class was modified pre war to increase the
capacity, it was launched in March 1940.

The built in assumptions on numbers and size of aircraft being
used played another part, RN carriers had lower hangars and
less aviation ordnance, so even when deck parks were used
this, along with accommodation limited capacity no matter how
much of the flight deck was parking space.

Essentially over the course of the war the USN carrier designs
and operating practices proved superior except in the very
area the RN carefully protected against, hits and especially
those causing fire and the built in risks of fire, with associated
damage and crew casualties.

The US aircraft carrier design results are flattered by the fact the
Japanese could not keep up aircrew quality, so fewer hits per
attack and easier interceptions of incoming strikes. It is also
clear the greater offensive power of USN carriers reduced the
chances of hits. It is also clear radar made a big difference to
carrier survivability.

Geoffrey Sinclair
Remove the nb for email.

[Kenneth Young]

Post by Geoffrey Sinclair
Essentially over the course of the war the USN carrier designs
and operating practices proved superior except in the very
area the RN carefully protected against, hits and especially
those causing fire and the built in risks of fire, with associated
damage and crew casualties.

This can be seen in the case of American built escort carriers. After one
RN one was destroyed the RN insisted on all of them being refitted to RN
standards off fuel handling. US comments were that the loss was due to
poor crew training and operation rather than ship construction. In other
words the Americans relied on their crews for safety rather than building
safety features in.

[Geoffrey Sinclair]

Post by Kenneth Young

Post by Geoffrey Sinclair
Essentially over the course of the war the USN carrier designs
and operating practices proved superior except in the very
area the RN carefully protected against, hits and especially
those causing fire and the built in risks of fire, with associated
damage and crew casualties.

This can be seen in the case of American built escort carriers. After one
RN one was destroyed the RN insisted on all of them being refitted to RN
standards off fuel handling. US comments were that the loss was due to
poor crew training and operation rather than ship construction. In other
words the Americans relied on their crews for safety rather than building
safety features in.

The modifications were more than the fuel system and it is
correct the USN damage control training was usually superior
to anyone else's. But damage control includes things built into
the ship.

HMS Avenger was considered lost due to the lack of protection
of the magazines from torpedo hits. As was USS Liscome Bay,
HMS Dasher from a fuel leak.

Both the USN and RN reduced the magazine space to 1
compartment on the centre line, which generally had additional
strengthening, the 2 wing magazines were turned into fuel tanks.
This kept weapons more than 10 to 15 feet from the ship's side.

In addition the RN did the following,

Add 1,000 to 1,300 tons of ballast to increase stability, plus
buoyancy tanks over some of the ballast to reduce lists from
underwater damage, avgas supply was cut to 25% of the original
capacity, later the RN system was fitted.

As noted all US built escort carriers had enclosed hangars.

Geoffrey Sinclair
Remove the nb for email.