US Navy Flying-Deck Cruiser (CF) (1930-1931)

[Triton]

Artist impression and line drawing of proposed Flying-Deck Cruiser (CF) by the United States Navy Bureau of Construction and Repair from 1930.

General Characteristics

Displacement (tons): 10,000 tons
Length (feet): 630
Beam (feet): 65
Draft (feet): 20

Flight Deck Type: Flush with island
Flight Deck Length: 340 feet

Maximum Speed (knots): 32.5 kts

Aviation Facilities: Open bay Hangar Deck To reduce fire hazards
* Flight deck - Both flying on and off
* One elevator forward
* One set of arresting gear Aft of the Elevator

Shaft Horse Power: 80,000

Radius of Action: 10,000 NM at 15 kts NM = nautical mile

Armament/Battery Primary: 3 triple 6-inch gun turrets

Secondary armament for anti-air: 6 5-inch guns
* .50 cal machine guns - Machine guns were to beportable assemblies.

Armor:

* “All or none configuration.”

* “8-inch” protection around magazines. “8-inch” refers to protection against 8-inch shell fire at long ranges.

* “6-inch” protection around machinery, turrets, and barbettes. 6-inch refers to protection against fire at intermediate to shorter ranges from other light cruisers.

Aircraft:
18 - hangar stowage
34 - hangar and flight deck stowage
Fighter (VF) and Scout (VO) equal numbers of each.

Source: "CF Flying Deck Cruiser"
http://www.globalsecurity.org/military/systems/ship/cf-specs.htm

 

[Triton]

Design "B" Flying-Deck Cruiser (CF) or (CVL) design.

 

[Triton]

CNO and the General Board design circa 1931.


General Characteristics

Displacement (tons): 10,000 tons
Length (feet): 627
Beam (feet): 65
Draft (feet): 20

Flight Deck Type: Aft with island
Flight Deck Length: 350 feet

Maximum Speed (knots): 32.5 kts

Aviation Facilities: Open bay Hangar Deck To reduce fire hazards
* Flight deck - Both flying on and off
* One elevator forward
* One set of arresting gear Aft of the Elevator

Shaft Horse Power: 80,000

Radius of Action: 10,000 NM at 15 kts NM = nautical mile

Armament/Battery Primary: 3 triple 6-inch gun turrets

Secondary armament for anti-air: 6 5-inch guns
* .50 cal machine guns - Machine guns were to be portable assemblies.
* 2 5-inch mounts aft

Armor:

6-inch” protection equal to that of a standard light cruiser. 6-inch refers to protection against fire at intermediate to shorter ranges from other light cruisers.

Aircraft:
24 VF and VO
Fighter (VF), Scout VO)

Source: "CF Flying Deck Cruiser"
http://www.globalsecurity.org/military/systems/ship/cf-specs.htm

Conjectural Flying Deck Cruiser design model by 1250ships.com.
http://www.1250ships.com/test/product_info.php?manufacturers_id=27&products_id=803

 

[Madurai]

There's a half a chapter devoted to the CF in Layman & MacLaughlin's The Hybrid Warship.

 

[Abraham Gubler]

There's a half a chapter devoted to the CF in Layman & MacLaughlin's The Hybrid Warship.

With the great conclusion that these CFs would have been converted to CVLs probably even before Pearl Harbour and within days after it if not before!

 

[Triton]

With the great conclusion that these CFs would have been converted to CVLs probably even before Pearl Harbour and within days after it if not before!

Is this because you believe that the flying-deck cruiser being a hybrid warship would offer little utility in the heavy cruiser role and the light aircraft carrier role? Was it better to construct pure heavy cruiser types, such as the Pensacola, Northhampton, Portland, or Wichita classes, instead of flight deck cruisers capable of launching 24 aircraft? With the 350 foot flight deck, would the flying-deck cruiser be limited to the types of aircraft in the US Navy inventory it could operate or the missions it could undertake?

 

[Abraham Gubler]

Is this because you believe that the flying-deck cruiser being a hybrid warship would offer little utility in the heavy cruiser role and the light aircraft carrier role?

I was referring to the book in question, page 103 and the last word on the USN's CLV/CF:

It seems that any flying-deck cruisers afloat in 1942 would have been re-modelled - not by yanking off the flight deck as suggested by Pratt, but by removing the guns and extending the flight deck over the length of the ship, as suggested by Land in 1934.

 

[Triton]

I was referring to the book in question, page 103 and the last word on the USN's CLV/CF:

It seems that any flying-deck cruisers afloat in 1942 would have been re-modelled - not by yanking off the flight deck as suggested by Pratt, but by removing the guns and extending the flight deck over the length of the ship, as suggested by Land in 1934.

OK, I thought it was a criticism directed toward the flying-deck cruiser proposal or hybrid warships. If I understand correctly, the US Navy Bureau of Ships revisited the hybrid flying-deck cruiser design again between 1939 and 1942. I also understand that the Royal Navy considered converting one or more Lion-class battleships to hybrid battleship/aircraft carriers during World War II.

It seems that the Imperial Japanese Navy was the only navy to order a hybrid warship during the Second World War, and these were conversions of the existing battleships IJN Ise and IJN Hyūga. If the resources had been available, the Imperial Japanese Navy would have preferred a full carrier conversion of these ships instead of hybrids.

Which makes me inclined to believe that pure warship types provide greater capability than hybrids and are therefore more desirable. Or did the US Navy build enough, or too many, cruisers during the inter-war years?

 

[royabulgaf]

What I find puzzling is this hybrid cruiser design reverts back to the fore-and-aft battery and flight deck of the traditional hybrid, when the USN perfected the hybrid cruiser in the Saratoga class carrier a few years before. This ship class offered not only a full flight deck, but a respectable cruiser armament of 8x8" guns. Was there some operational problems with these ships that would cause the USN to take a step back? IIRC, they never fired their main armament in WWII, and in fact offloaded their guns at the first opportunity.

 

[Abraham Gubler]

OK, I thought it was a criticism directed toward the flying-deck cruiser proposal or hybrid warships. If I understand correctly, the US Navy Bureau of Ships revisited the hybrid flying-deck cruiser design again between 1939 and 1942. I also understand that the Royal Navy considered converting one or more Lion-class battleships to hybrid battleship/aircraft carriers during World War II.

I'm more than happy to criticise the design because they are proven not to work efficiently and it is pretty obvious that such hybrids suffer a lot from either area of hybridisation impacting on the other. They may look cool but they don’t work.

Layman and McLaughlin’s book (The Hybrid Warship) does detail the later efforts of the USN and RN in the 40s towards hybrids. But these are not efforts being motivated by introducing a new superior type of ship but rather to try and get more aircraft capability into the fleet as rapidly as possible. Which meant what can we do with less effective units like gun wagons and cruisers to try and get the most out of them. They made the right conclusion that such a hybrid wasn’t worth the effort and the existing programmed units should either be converted to full aviation capability or put aside and resources diverted to carriers. The Japanese in a far more perilous situation carried out minimal conversions of some of their BBs to leverage their heavy investment in float planes to try and get more aircraft into the fleet. I’m sure they would have preferred to retain a BB and have built a new carrier.

What I find puzzling is this hybrid cruiser design reverts back to the fore-and-aft battery and flight deck of the traditional hybrid, when the USN perfected the hybrid cruiser in the Saratoga class carrier a few years before. This ship class offered not only a full flight deck, but a respectable cruiser armament of 8x8" guns. Was there some operational problems with these ships that would cause the USN to take a step back? IIRC, they never fired their main armament in WWII, and in fact offloaded their guns at the first opportunity.

The Saratogas were 40,000 tonne ships so could afford a full flight deck with 8x8s. Because of treaty limitations the size of the proposed hybrid cruisers was much smaller so they had to share hull length between guns and flight deck.

The experience of the Saratoga 8” guns showed how useless such hybrids was. Because the carrier manoeuvred to launch aircraft they were split from the battle line and didn’t need to use their guns. Also the firing of guns severely affected any aircraft parked on deck which also limited the guns training arcs. The guns were found to be superfluous and harmful to the most effective part of the ship: the air wing.

 

[smurf]

Saratoga was not a hybrid, but a full-fledged carrier converted from a battlecruiser hull.
Her 8in guns were not to enable her to act as a cruiser, but to allow her to defend herself against cruiser attack when it was necessary for her to steam away from the main fleet to fly her aircraft. The Washington Treaty cruisers of her day were armed with 8in guns. Her 8in were replaced by 5in DP in 1942.

On hybrids. Once you move away from considering what a single ship might do, to considering what a fleet, or even a small task force, might do, the disadvantages become clearer. As AG mentioned, each opposing features of a hybrid act to the detriment of the other.
The RN Lion hybrid scheme was quickly killed by the Director of Naval Construction:
5 hybrids 70 aircraft, 30x15in guns 225,000tons
3 Lions, 3 Indomitables 144 aircraft, 27x16in guns, 200,000tons.
(DK Brown, Nelson to Vanguard quoting ADM 1/11051 16 July 1941)
With cost roughly proportional to displacement, the choice is obvious.

 

[Just call me Ray]

It seems that the Imperial Japanese Navy was the only navy to order a hybrid warship during the Second World War, and these were conversions of the existing battleships IJN Ise and IJN Hyūga. If the resources had been available, the Imperial Japanese Navy would have preferred a full carrier conversion of these ships instead of hybrids.

If the resources were available the Imperial Japanese Navy probably would've wanted to find another hull to convert or build a new carrier; Ise and Hyuga were slow and old, comparable in speed and age to a USN New Mexico class battleship. These conversions, at least according to my understanding, were more or less out of desperation to begin with.

 

[Grey Havoc]

On a side note, a 'whatif', from Theodore over at HP&CA:

http://www.tboverse.us/HPCAFORUM/phpBB3/viewtopic.php?f=15&t=9777

 

[Grey Havoc]

The U.S.briefly considered an angled deck in the 1930s, though this was in a different context. The US designed a cruiser with a flight deck and the 'final' 1931 design had an angled deck, though instead of directing the landing planes away from parked aircraft it was intended to direct them away from the end of the flight deck and the main battery turrets ahead of it. The vessel was re-ordered as one of the Brooklyn class. Later when the concept was briefly revived around 1940 the designs contemplated had straight, albeit longer decks.it would be a small leap to recognize the utility of the arrangement but it was a leap the U.S.N. did not make.

 

[airman]

This type of ships i have seen in " Hybrid Warship" .

 

[Brickmuppet]

The hybrid Cruiser Carrier was developed in the context of the Washington and London naval armaments limitation treaties. While it was thought (in the absence of actual experience) that a cruiser with, say two dozen aircraft might have some utility in some specialized niches like convoy work and scouting, the main point of the design was to get more flight decks into the fleet than were nominally allowed by the treaties. If the flight deck was half the length between perpindiculars or less it counted legally as a cruiser, thus this was adding flight decks, which the U.S.N. desperately wanted. Once there were no treaty restrictions the U.S.N built scores of escort carriers which did the jobs this ship was supposed to better than it could have, and lots of cruisers and picket vessels.

I tend to agree with those above that they'd likely have been converted to full carriers rather quickly.

 

[Julio Garay Terrazas]

I found this little link: https://alchetron.com/Flight-deck-cruiser

 

[David Chessum]

... If the flight deck was half the length between perpindiculars or less it counted legally as a cruiser, ...

This is not quite right. The relevant clause of LNT30 was:

"The expression "aircraft carrier" includes any surface vessel of war, whatever its displacement, designed for the specific and exclusive purpose of carrying aircraft and so constructed that aircraft can be launched therefrom and landed thereon.

2. The fitting of a landing-on or flying-off platform or deck on a capital ship, cruiser or destroyer, provided such vessel was not designed or adapted exclusively as an aircraft carrier, shall not cause any vessel so fitted to be charged against or classified in the category of aircraft carriers."

Regards

David

 

[awhalen61]

Here's a pair of very rough sketches drawn by a member of the USN delegation during the middle of the First London Naval Conference in 1930. These were in a large stack of loose leaf papers from that time period, and I did not see any more information about these designs.

 

[Scott Kenny]

If the resources were available the Imperial Japanese Navy probably would've wanted to find another hull to convert or build a new carrier; Ise and Hyuga were slow and old, comparable in speed and age to a USN New Mexico class battleship. These conversions, at least according to my understanding, were more or less out of desperation to begin with.

IIRC both Ise and Hyuga had been damaged and were in for repair at the time, then Japan lost a lot of carriers. It was a lot faster to pull the rear two turrets off and install a flight deck than it would be to try to build whole new carriers.

 

[David Chessum]

Here's a pair of very rough sketches drawn by a member of the USN delegation during the middle of the First London Naval Conference in 1930. These were in a large stack of loose leaf papers from that time period, and I did not see any more information about these designs.

Thank you for posting these. Do you have a citation for the archive file these came from?

Best regards

David

 

[H_K]

Here's a pair of very rough sketches drawn by a member of the USN delegation during the middle of the First London Naval Conference in 1930. These were in a large stack of loose leaf papers from that time period, and I did not see any more information about these designs.

The first sketch looks like the same hull as a Pensacola class 9,000tW heavy cruiser... 570ft waterline length, 63ft beam, similar turret arrangement (2 turrets at the stern). So 3x 8" turrets (twin or triple turrets? 6 to 9 guns)

Machinery arrangement is different however, with the boilers moved to behind the machinery rooms... probably to deconflict the funnels <-> flight deck.

 

[EwenS]

IIRC both Ise and Hyuga had been damaged and were in for repair at the time, then Japan lost a lot of carriers. It was a lot faster to pull the rear two turrets off and install a flight deck than it would be to try to build whole new carriers.

Hyuga suffered damage on 5 May 1942 when, during a gunnery exercise in Japanese home waters, the left gun breech in turret no 5 blew up. The magazines for the two aft turrets had to be flooded to protect the ship. She was repaired at Kure 6-25 May 1942. That involved removal of no 5 turret and placing a circular armoured plate over the barbette opening with 3 triple 25mm AA monunts on it. She participated in the Aleutian operation in June and suffered no further damage before her conversion to a battleship carrier.

Ise, despite suffering some accidental engine room flooding in May 1942, was also able to participate in the Aleutian operation in June and suffered no further damage before her conversion.

The first steps taken by the IJN post Midway to improve their carrier stock were as follows:-
1. accelerated construction of 15 medium carriers based on Hiryu (more Unryu class with 2 laid down by end of 1942) and 5 fleet carriers on a modified Taiho design, (construction not expected to begin until 1944).
2. conversion of specially designed ships into their planned light carrier configuration (Chitose & Chiyoda work began Jan 1943 completed Dec 1943 / Jan 1944)
3. conversion of selected emerchant ships to escort carriers (Kaiyo & Shinyo)
4. conversion of Warship No 110 to a carrier (Shinano)

The above were not expected to produce fruit until 1944 and a quicker solution was sought. Early on Ise & Hyuga were to be the first BB conversions with others to follow. Various proposals for the conversion were made from full carrier, through 2, 3 & 4 turret versions. Eventually towards the end of 1942 the 4 turret version was chosen.

Officially work on Ise began in Dec 1942 but other evidence suggests it was Feb 1943. She completed on 5 Sept 1943. Hyuga was converted between 2 May 1943 and 30 Nov 1943. Delays crept into the programme due to other repair work.

They were designed to only launch aircraft, which would then return to land ashore or on other carriers. At the end of the day they only operated aircraft during a few trials and never operationally. So the whole conversion process was a waste of time.

Finally the decision to convert the incomplete hull of the cruiser Ibuki into a carrier was taken in the third quarter of 1943.

 

[Scott Kenny]

Apparently I did not remember correctly. :facepalm:

Point still stands about it being faster to pull two or even four turrets off a battleship that was already in existence than to build new carriers, however.

 

[Avimimus]

Saratoga was not a hybrid, but a full-fledged carrier converted from a battlecruiser hull.
Her 8in guns were not to enable her to act as a cruiser, but to allow her to defend herself against cruiser attack when it was necessary for her to steam away from the main fleet to fly her aircraft. The Washington Treaty cruisers of her day were armed with 8in guns. Her 8in were replaced by 5in DP in 1942.

On hybrids. Once you move away from considering what a single ship might do, to considering what a fleet, or even a small task force, might do, the disadvantages become clearer. As AG mentioned, each opposing features of a hybrid act to the detriment of the other.
The RN Lion hybrid scheme was quickly killed by the Director of Naval Construction:
5 hybrids 70 aircraft, 30x15in guns 225,000tons
3 Lions, 3 Indomitables 144 aircraft, 27x16in guns, 200,000tons.
(DK Brown, Nelson to Vanguard quoting ADM 1/11051 16 July 1941)
With cost roughly proportional to displacement, the choice is obvious.

Definitely true. However, the one exception might be a scout cruiser or surface raider, operating at long ranges with little or no destroyer escort.

Under such conditions the ability to carry aircraft allows:
- Increased scouting ability (including increased likelihood of evading the enemy).
- An ability to harass attacking enemy aircraft (if carrying fighters).
- Ambushing ships at anchor (especially in smaller less defended ports).
- Potentially attacking a much larger warship by surprise.

At the same time the 2"-4" of armour and quick firing light cruiser armament allows a degree of self-defense against enemy destroyers in conditions of low visibility or if destroyers try to run down the hybrid-cruiser.

There are still engineering issues though - questions about the effectiveness of the protection scheme (even against destroyer equipped guns), and the relatively small air group (which would be ineffective against larger formations of enemy ships, larger ports, or a large number of attacking enemy aircraft). There are probably situations where they'd make excellent raiders though, especially against smaller colonial holdings. If one looks at the success of SMS Wolf for example... then imagine such a ship with twenty aircraft, close to thirty knots and nine six inch guns... I'm not sure such a ship would be a worse choice than, say, the Admiral Hipper class.

So, in a sense, I've always seen the USN Flying-Deck cruisers as the most hybrid practical designs - just perhaps for a smaller country than the U.S. (i.e. one which might want a ship on station somewhere, but not be able to afford more than one).

 

[Scott Kenny]

Definitely true. However, the one exception might be a scout cruiser or surface raider, operating at long ranges with little or no destroyer escort.

Under such conditions the ability to carry aircraft allows:
- Increased scouting ability (including increased likelihood of evading the enemy).
- An ability to harass attacking enemy aircraft (if carrying fighters).
- Ambushing ships at anchor (especially in smaller less defended ports).
- Potentially attacking a much larger warship by surprise.

At the same time the 2"-4" of armour and quick firing light cruiser armament allows a degree of self-defense against enemy destroyers in conditions of low visibility or if destroyers try to run down the hybrid-cruiser.

There are still engineering issues though - questions about the effectiveness of the protection scheme (even against destroyer equipped guns), and the relatively small air group (which would be ineffective against larger formations of enemy ships, larger ports, or a large number of attacking enemy aircraft). There are probably situations where they'd make excellent raiders though, especially against smaller colonial holdings. If one looks at the success of SMS Wolf for example... then imagine such a ship with twenty aircraft, close to thirty knots and nine six inch guns... I'm not sure such a ship would be a worse choice than, say, the Admiral Hipper class.

So, in a sense, I've always seen the USN Flying-Deck cruisers as the most hybrid practical designs - just perhaps for a smaller country than the U.S. (i.e. one which might want a ship on station somewhere, but not be able to afford more than one).

So, like the Tone-class cruisers for Japan?

 

[EwenS]

So, like the Tone-class cruisers for Japan?

No not like the Tone class at all, which were never intended for independent operation.

There was a fundamental difference between the USN and IJN naval aviation forces. In the USN the carrier air groups had a Scout squadron whose responsibilty was recce to locate an enemy fleet. While the cruisers and capital ships carried floatplanes their primary role was scouting for those ships and observation to assist with their gunnery.

The IJN intended to hold back all its carrier torpedo and dive bombers until an enemy was located and use them to strike hard. Finding an enemy was a responsibilty exported to the floatplanes on escorting warships. Recce therefore became the primary function of the floatplanes carried by the cruisers. This can be seen in the early war operations of the IJN like Operation C and Midway where the bulk of the recce was carried out by floatplanes with only a couple of Kates allocated from the carriers to assist in the task during some operations.

The IJN increased the number of floatplanes on their cruisers from 2 (Aoba & Myoko) to 3 (Takao & Mogami) to a planned 4 in the earliest proposals for the Tones. This was increased to a planned 6-8 when the design was revised as an "aircraft cruiser" which saw the all the main armament forward (partly to protect the aircraft to be parked aft since there was no hangar). These were intended to be 2-4 E7K2 Alf 3 seat and 4 E8N2 Dave 2 seat biplane recce aircraft. In practice it was found that no more than 5 could be carried and more usually 4 (2 of each type). Later these were replaced by 3 seat Aichi E13A1 and 2 seat Mitsubishi F1M1. The lack of a protective hangar for the larger number of aircraft seems to have been the principal cause for the reduction.

When you look at the deployment of the Tones during the war, it is mostly as escort to the carriers, providing that recce function.

After Midway the IJN came to realise that it did not have enough recce assets supporting the carriers. Hence the decision to reconstruct the already heavily damaged Mogami as an "aircraft cruiser". She was then equipped to carry 11 seaplanes (initially just 4xE13A1 and 3xF1M1. Later the Aichi E16A Paul was intended as the replacement).

 

[Julio Garay Terrazas]

Hyuga suffered damage on 5 May 1942 when, during a gunnery exercise in Japanese home waters, the left gun breech in turret no 5 blew up. The magazines for the two aft turrets had to be flooded to protect the ship. She was repaired at Kure 6-25 May 1942. That involved removal of no 5 turret and placing a circular armoured plate over the barbette opening with 3 triple 25mm AA monunts on it. She participated in the Aleutian operation in June and suffered no further damage before her conversion to a battleship carrier.

Ise, despite suffering some accidental engine room flooding in May 1942, was also able to participate in the Aleutian operation in June and suffered no further damage before her conversion.

The first steps taken by the IJN post Midway to improve their carrier stock were as follows:-
1. accelerated construction of 15 medium carriers based on Hiryu (more Unryu class with 2 laid down by end of 1942) and 5 fleet carriers on a modified Taiho design, (construction not expected to begin until 1944).
2. conversion of specially designed ships into their planned light carrier configuration (Chitose & Chiyoda work began Jan 1943 completed Dec 1943 / Jan 1944)
3. conversion of selected emerchant ships to escort carriers (Kaiyo & Shinyo)
4. conversion of Warship No 110 to a carrier (Shinano)

The above were not expected to produce fruit until 1944 and a quicker solution was sought. Early on Ise & Hyuga were to be the first BB conversions with others to follow. Various proposals for the conversion were made from full carrier, through 2, 3 & 4 turret versions. Eventually towards the end of 1942 the 4 turret version was chosen.

Officially work on Ise began in Dec 1942 but other evidence suggests it was Feb 1943. She completed on 5 Sept 1943. Hyuga was converted between 2 May 1943 and 30 Nov 1943. Delays crept into the programme due to other repair work.

They were designed to only launch aircraft, which would then return to land ashore or on other carriers. At the end of the day they only operated aircraft during a few trials and never operationally. So the whole conversion process was a waste of time.

Finally the decision to convert the incomplete hull of the cruiser Ibuki into a carrier was taken in the third quarter of 1943.

About Hyuga and Yamashiro class convertions, ome images that I have in my PC...

 

[PMN1]

What was the expected aircraft complement for a full conversion?

 

[DWG]

Definitely true. However, the one exception might be a scout cruiser or surface raider, operating at long ranges with little or no destroyer escort.

Under such conditions the ability to carry aircraft allows:
- Increased scouting ability (including increased likelihood of evading the enemy).
- An ability to harass attacking enemy aircraft (if carrying fighters).
- Ambushing ships at anchor (especially in smaller less defended ports).
- Potentially attacking a much larger warship by surprise.

The RN proposed to achieve much the same in the mid-30s by shipping 3 TSRs with bombs and torpedoes on conventional cruisers in place of Walrus. It's why the Swordfish was developed with floats and a catapult capability, not just the carrier capability.

 

[Avimimus]

The RN proposed to achieve much the same in the mid-30s by shipping 3 TSRs with bombs and torpedoes on conventional cruisers in place of Walrus. It's why the Swordfish was developed with floats and a catapult capability, not just the carrier capability.

Ah! Very neat to know!