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PostPosted: Fri Apr 15, 2016 10:09 pm 
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Good evening,

I'm a CLAA lover, not just the Atlantas but also the Didos and other smaller AA ships, either purpose built or converted. My question is, has there ever been a survey of their effectiveness, and which was most effective in that role? I understand that anti-aircraft defense may not have been their as-designed role, the Atlantas being large screening ships for the battle line initially, but in the end, historically they're viewed as AA ships rightly or wrongly. So, has their relative effectiveness ever been really rated or compared? Atlanta versus Dido, for example? How the Japanese refits fared (I'm thinking of Maya in 1944 here, not at true AA ship but certainly more AA-centric by IJN standards)? Or, even the Wairs?

Sorry if this is a fanboy question, but in my travels I just haven't come across this information.

Thank you,

Bob


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PostPosted: Sat Apr 16, 2016 10:01 am 
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According to Raven/Roberts the converted C class anti-aircraft cruisers were more effective than the Dido class (not really a CLAA, but a light cruiser with dual purpose guns). The argument was that the 4 in guns of C class cruisers were the better AA guns compared to the 5.25 in guns of the Dido class.

I have also read that the Atlanta class was not designed as anti-aircraft cruiser, but as cruisers, which should defend the fleet, e.g. against destroyer attacks at night.

Cheers,
Lars

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PostPosted: Sat Apr 16, 2016 5:55 pm 
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This is a question that likely won't get an absolute answer. Particularly if you are comparing ships built by different navies. The number and type of guns, and their rate of fire, used on various ships have to be evaluated along with the fire control systems utilized by those same ships.

The first four ATLANTA class units were appreciated when they arrived in context that except for the Fast Battleships which were available in limited numbers during 1942, none of the pre-WWII cruisers had as many 5-in/38 cal guns that could be used at range against attacking aircraft. Also, in contrast to the pre-WWII cruisers the ATLANTA's had radar control on the new Mk 37 directors. The addition of the ATLANTA's to the Carrier Task Forces in mid-to-late 1942 was a big boost to the total Task Force AA-firepower. Once the CLEVELAND class cruisers came on-line with their twelve 5-in guns and more 40-mm guns, they were just about as useful. The problem with the ATLANTA's as cruisers, they really weren't that useful in the surface warfare arena as was seen off Guadalcanal in November 1942. Even though their design started out as a larger Destroyer Leaders to provide cover fire for attacking destroyers, they were found to be more vulnerable than a classic cruiser in surface actions. So they quickly were seen as being primarily "AA-Cruisers". The second batch of four ATLANTA class cruisers didn't come on line until late 1943 into 1944 and were limited to being AA escorts for carriers. The Fast Battleships with twenty 5-in guns and four Mk 37 directors, were seen as being superb AA-escorts.

I don't know if the USN could readily breakdown which ships in a Task Force were responsible for destroying which aircraft when everything from destroyers up to carriers were firing 5-in/38 cal guns at the enemy. I have read that the most effective Anti-Aircraft weapon was a fighter plane. I won't get into how many times more than one destroyer claimed to have killed the same aircraft. :smallsmile:

I can't speak to RN use of their so called Anti-Aircraft cruisers and their effectiveness. Operationally, they used these ships differently than the USN. Many were assigned to the Med where AA-firepower was important since practically every other ship in the RN had limited AA-firepower. Go post this question on Steelnavy and Al Raven will likely give more details.


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PostPosted: Sun Apr 17, 2016 11:58 am 
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Please indulge me this next to useless comment, it draws from a somewhat parallel development and is in line with Rick's statement that there probably isn't an absolute answer. The example I'm referring to is the outfitting of B-17s with additional gun stations and crates upon crates of .50-caliber ammunition in place of a regular bombload so that to some extent these aircraft, placed among the bomb group, would be a flying antiaircraft battery (can't recall if these had a special designation). Lots of firepower to fend off attacking Messerschmitts and Focke-Wulfs.

The logic was sound, but the results really didn't bear out, probably because as powerful as these aircraft were, they still operated only within a relatively small part of the "battle space," similar to the CLAAs. Again as Rick alluded, the most effective antiaircraft weapon was the fighter plane, the Hellcats and Corsairs in the Pacific, in the case of the European airwar, the P-51.


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PostPosted: Sun Apr 17, 2016 12:16 pm 
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Rick E Davis wrote:
Even though their design started out as a larger Destroyer Leaders to provide cover fire for attacking destroyers, they were found to be more vulnerable than a classic cruiser in surface actions.


I wonder is this is true or if there was a bigger need for AA ships. Two ships of the class were sunk in surface actions - but in this area the USN lost in addition to the two Atlantas 4 heavy cruisers and 1 light cruiser; 5 heavy cruisers and 3 light cruisers were heavily damaged. Atlanta got so many hits (including 8 in friendly fire) that it is unlikely that a heavy cruiser in her position would have survived. Juneau was hit by two 61 cm torpedoes at the same place, which sunk her - and probably also most other cruisers of that period. From the statistics the heavy cruisers were probably more vulnerable than the Atlantas.

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PostPosted: Sun Apr 17, 2016 5:13 pm 
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maxim wrote:
Rick E Davis wrote:
Even though their design started out as a larger Destroyer Leaders to provide cover fire for attacking destroyers, they were found to be more vulnerable than a classic cruiser in surface actions.


I wonder is this is true or if there was a bigger need for AA ships. Two ships of the class were sunk in surface actions - but in this area the USN lost in addition to the two Atlantas 4 heavy cruisers and 1 light cruiser; 5 heavy cruisers and 3 light cruisers were heavily damaged. Atlanta got so many hits (including 8 in friendly fire) that it is unlikely that a heavy cruiser in her position would have survived. Juneau was hit by two 61 cm torpedoes at the same place, which sunk her - and probably also most other cruisers of that period. From the statistics the heavy cruisers were probably more vulnerable than the Atlantas.

The irony is that the Atlanta's were intended for surface action, but the one time they did it they were still not used exactly as intended. They were supposed to be leaders for destroyers and more free to move about. But at Guadalcanal, they were chained to the main battle line and denied their mobility. They paid a high price for that. The original design concept also included AA screening for the main fleet units, but since that was also built into most of the newer DD's, that still fit with their intended position as "leaders" for those destroyers. In all fairness, though, what caused them to be denied more surface actions was not just the one battle. The whole battle-fleet surface action concept was sunk with the battleships at Pearl Harbor. Without that battle fleet, there was no real need for leaders fighting to get their destroyers through the enemy screen in a torpedo attack. So in the small-scale, close-quarters fighting in the Solomons, the Atlanta's were more of a liability than an asset. Their original mission was gone ultimately leaving them only the screening function.

MareNostrum wrote:
The example I'm referring to is the outfitting of B-17s with additional gun stations and crates upon crates of .50-caliber ammunition in place of a regular bombload so that to some extent these aircraft, placed among the bomb group, would be a flying antiaircraft battery (can't recall if these had a special designation). Lots of firepower to fend off attacking Messerschmitts and Focke-Wulfs.

The modified B-17 was designated YB-40.


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PostPosted: Sun Apr 17, 2016 9:27 pm 
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Dick J wrote:
The modified B-17 was designated YB-40.

Yes, that's right, thank you.


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PostPosted: Sun Apr 17, 2016 10:59 pm 
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Maxim,

JUNEAU's own CO was concerned about his new ship being involved in a Surface Action. 5-in guns against IJN 8-in guns and Long Lance torpedoes didn't seem to be a fair match to him against his lightly armored cruiser. JUNEAU had an SG radar at the time of her loss, but her sister ATLANTA didn't. I'm not sure which of the Heavy Cruisers when they were lost in night engagements with the IJN had the SG radar. In late 1942, the USN was not prepared to fight the IJN at night without the SG radar and experience using it.

Even by May 1942 when the first of the ATLANTA class cruisers arrived in the Pacific, their value as AA-escorts was obvious. All four were assigned to the existing Aircraft Carrier Task Forces in June 1942, not to Surface Action Groups. They filled in with the SAGs around Guadalcanal after most of the USN carriers were sunk or disabled.


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PostPosted: Sun Apr 17, 2016 11:41 pm 
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In a day action a Atlanta for sure would have problems against a Japanese heavy cruiser. But for the night actions they should have been much better.

I have not seen any evidence that heavy cruiser armour was useful. The most heavily armed pre-war heavy cruisers, the New Orleans class, suffered terribly, in surface actions and the three of them would have been probably also disable at Savo by gun fire alone.

The SG sets are difficult to identify, but remember that the USN had severe problems with IJN night fighting tactics as late as July 1943 (Battle of Kula Gulf and Battle of Kolombangara). At that time probably all cruisers had SG radar.

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PostPosted: Mon Apr 18, 2016 10:44 am 
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maxim wrote:
I have not seen any evidence that heavy cruiser armour was useful. The most heavily armed pre-war heavy cruisers, the New Orleans class, suffered terribly, in surface actions and the three of them would have been probably also disable at Savo by gun fire alone.

I would tend to put the loss of the three cruisers at Savo down more to "operator error" rather than "design malfunction". ANY ship can be sunk if it is allowed to act as a target and not react properly to the threat - no matter how well protected. The three ships at Savo were targeted before they were at battle stations, were on fire before they could respond, and allowed the Japanese to remain in a continual "crossing of the T" position (granted, across the stern rather than the bow) for most of the action. The captain of the Vincennes did not increase speed or initiate a significant turn to engage the threat, and so kept his ships wallowing in the target zone for the entire action. That was not a fair test of the design in its intended role. As for San Francisco, no 8" gunned cruiser was armored to withstand 14" gun fire.
maxim wrote:
The SG sets are difficult to identify, but remember that the USN had severe problems with IJN night fighting tactics as late as July 1943 (Battle of Kula Gulf and Battle of Kolombangara). At that time probably all cruisers had SG radar.

The SG set was needed for the night battles but was not the only solution required. The MK-3 fire control radar had its own issues that prevented the US ships from properly targeting the IJN units identified by the SG. So until the MK-8 was available, the US cruisers could not properly react to the incoming threats. At Empress Augusta Bay, the US flagship (Montplier) and one other cruiser (Denver) had MK-8 radar. Later, after Denver was torpedoed, she returned to the US for repairs without her MK-8's. At about the same time, Cleveland and Columbia had their forward MK-3's replaced by MK-8's, so I think that the lesson was learned. At Surigao Strait, the US ships with MK-8 or MK-13 radar did well against the IJN. The ships with only MK-3 had problems, leading to the replacement of the after director on Pennsylvania, Colorado and Maryland with a MK-34 director which could handle the MK-8 and MK-13 radars.


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PostPosted: Mon Apr 18, 2016 11:15 am 
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As you can see most of the USN cruiser losses in the Pacific were due to IJN TORPEDOES. Several others were badly damaged, but survived.

USN Cruiser losses in WWII;

OMAHA Class ... None Lost

PENSACOLA Class ... None Lost

CA-24 PENSACOLA
CA-25 SALT LAKE CITY


NORTHAMPTON Class ... Three out of Six Lost

CA-26 NORTHAMTON ... Sunk 1 December 1942 by IJN Long Lance torpedoes
CA-27 CHESTER
CA-28 LOUISVILLE
CA-29 CHICAGO ... Sunk 30 January 1943 by SIX Japanese Aircraft torpedoes
CA-30 HOUSTON ... Sunk 1 March 1942 by FOUR IJN Long Lance torpedoes

CA-31 AUGUSTA (Atlantic Fleet during WWII)

INDIANAPOLIS Class ... One out of Two Lost

CA-33 PORTLAND
CA-35 INDIANAPOLIS ... Sunk 29 July 1945 by IJN Submarine

NEW ORLEANS Class ... Three out of Seven Lost

CA-32 NEW ORLEANS
CA-34 ASTORIA ... Sunk 9 August 1942 by IJN Cruiser Gunfire
CA-36 MINNEAPOLIS

CA-37 TUSCALOOSA (Atlantic Fleet during WWII)
CA-38 SAN FRANCISCO
CA-39 QUINCY ... Sunk 9 August 1942 by IJN Cruiser Gunfire and TWO or Three Long Lance torpedoes
CA-44 VINCENNES ... Sunk 9 August 1942 by IJN Cruiser Gunfire and Long Lance torpedoes

WICHITA Class ... None Lost

CA-45 WICHITA

BROOKLYN Class ... One out of Nine Lost

CL-40 BROOKLYN (Atlantic Fleet during WWII)
CL-41 PHILADELPHIA (Atlantic Fleet during WWII)
CL-42 SAVANNAH (Atlantic Fleet during WWII)
CL-43 NASHVILLE
CL-46 PHOENIX
CL-47 BOISE
CL-48 HONOLULU
CL-49 ST. LOUIS
CL-50 HELENA ... Sunk 6 July 1943 by THREE IJN Long Lance torpedoes


ATLANTA Class - 1st Group ... Two out of Four Lost

CL-51 ATLANTA ... Sunk 13 November 1942 by USN and IJN Gunfire and an IJN Long Lance torpedo
CL-52 JUNEAU ... Sunk 13 November 1942 by ONE IJN Long Lance torpedo and ONE IJN Submarine torpedo
CL-53 SAN DIEGO
CL-54 SAN JUAN

BALTIMORE and CLEVELAND Classes ... None


Last edited by Rick E Davis on Mon Apr 18, 2016 5:30 pm, edited 1 time in total.

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PostPosted: Mon Apr 18, 2016 12:00 pm 
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To be fair and more exact (it doesn't change the substance..)

USS ATLANTA was scuttled, not sunk outright. She was very severely damaged during the night action and was put out of action by the long lance, however she did survive the night. Given the severe and extensive damage she received it would have been highly difficult to rescue her, even if local repair facilities were immediately available. She was scuttled by demolition charges and sank in 400 ft of water.

It's entirely likely that ATLANTA would have sunk on her own, however ultimately she was scuttled.


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PostPosted: Mon Apr 18, 2016 12:02 pm 
Problem with the B-40s was that they still didn't have enough firepower. Further, once the B-17s dropped their bombs, they were lighter than the B-40s. The B-40s had a hard time keeping up.

The only effective method to protect the bombers was with fighters.

Much like ships, no matter how much AAA was crammed on board, it wasn't enough. The only effective method to protect the ships was with fighters.


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PostPosted: Mon Apr 18, 2016 12:04 pm 
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And additionally..it was eventually found that the Atlanta (Oakland subclass too) were very effective AA cruisers, but were designed as scout cruisers, similar to the concept of the Chester and Omaha class CL's. As was previously noted, they were also to act as destroyer squadron/float leaders and acting as localized C&C ships.


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PostPosted: Mon Apr 18, 2016 1:41 pm 
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@ Dick J: I do not think that Savo proved that the New Orleans were a bad design - the New Orleans class was for sure the best pre-war USN heavy cruiser except probably of USS Wichita. My point was that there is no proof that heavy cruiser armour had any use. Even in gun actions heavily armoured ships were disabled. Rick's list would be other argument - the deadliest weapon was the torpedo.

USN gun fire was already good during the Battle of Kula Gulf and Battle of Kolombangara. In both battles the Japanese flagship was rapidly disabled - but in both battles the Japanese counter attack was successful. Also at Tassafaronga the leading Japanese ship as sunk by gun fire - but again the Japanese torpedo attack was successful. Was that a problem that these Japanese destroyers were not detected? Or not been hit?

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PostPosted: Mon Apr 18, 2016 3:42 pm 
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maxim wrote:
@ Dick J: I do not think that Savo proved that the New Orleans were a bad design - the New Orleans class was for sure the best pre-war USN heavy cruiser except probably of USS Wichita. My point was that there is no proof that heavy cruiser armour had any use. Even in gun actions heavily armoured ships were disabled. Rick's list would be other argument - the deadliest weapon was the torpedo.

Even the best of the armored ships will be sunk if they allow themselves to become a static target. Armor does not make a ship immune. It buys time for you to disable the other guy before he disables you. And armor provides an "immune zone" where the armor is most effective. At Savo, the Japanese were already inside the inner edge of that zone, so essentially it was as if there was nothing to stop the shells. In order to have a meaningful test of the value of armor, you need a battle where both sides are prepared and can maneuver their ships to the best advantage. Also, it might have been useful to have something like a Northampton and a New Orleans side by side to see which was disable first and find out if the New Orleans' armor bought enough time. Since no such action occurred, it is difficult to say whether or not the armor added value.

maxim wrote:
USN gun fire was already good during the Battle of Kula Gulf and Battle of Kolombangara. In both battles the Japanese flagship was rapidly disabled - but in both battles the Japanese counter attack was successful. Also at Tassafaronga the leading Japanese ship as sunk by gun fire - but again the Japanese torpedo attack was successful. Was that a problem that these Japanese destroyers were not detected? Or not been hit?

The problem with the MK-3 was that it reflected off too many things, including shell splashes. (In fact, the shell splashes produced a stronger return than the ship did.) To reduce that a bit, the radars were "range gated", meaning that you set a near and far range value and only the echoes in that range were displayed. But when you target a fast ship, such as a destroyer, it will maneuver rapidly when the first shell splashes show up. The DD will quickly exit the range set for the MK-3, but the shell splashes will remain. The shooter will still see a "target" (shell splashes) and concentrate on that, leaving the DD free to launch its torpedo attack. In the mean time, the US cruiser would cease fire, see no remaining target, and assume that it had been sunk. Then the torpedoes started arriving and the cruisers paid the price. The MK-8 could follow the target better and keep him busy if not disable him more quickly. So it made a huge difference in a night action. At Surigao, Maryland couldn't range off of the IJN BB (probably Yamashiro, but some argue that point), but she could range off of West Virginia's shell splashes.

BTW, one correction to Rick's list: Quincy was hit by at least two and possibly three torpedoes. Also, what sank the Astoria was the fire that continued afterward that cooked off a 5" magazine and finally put her under. So had they been able to put out that fire, she might have survived.


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PostPosted: Mon Apr 18, 2016 5:28 pm 
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Thanks Dick, I was trying to write up a quick summary ... my point was most of the USN cruiser losses were due to or a major contributor of torpedoes.

The ATLANTA's pumped a lot of shells at the enemy before being "immobilized", but the "Killing Power" of 5-in shells wasn't as great as 8-in or even 6-in shells.

One other thing to point out, the ATLANTA's had for both AA and Surface fire control only the Mk 37 director with the early Mk 4 (FD) radar. In other words they didn't have a dedicated surface engagement fire control system. The Mk 4 had a drawback when used to target at horizon level against aircraft or ship targets. Ground/Sea clutter reduced targeting effectiveness. Destroyers with the Mk 37 director/Mk 4 radar combo encountered a limited range of accuracy against so called surface level targets. This was the reason that the Mk 12/22 radar pair were developed as a replacement for the Mk 4 radar. The Mk 12 operated at a different frequency and was higher powered. The Mk 22 provided an elevation beam.


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PostPosted: Mon Apr 18, 2016 11:52 pm 
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Thank your for explaining the problems of the Mk 3 radar and the Mk 4 radar.

But again to the armour: is their an example that cruiser armour was useful? There are plenty of examples that it was not, e.g. the Battles of Savo and Guadalcanal. For sure you can argue that the armour was not designed for these ranges, but that is the same argument as that it was useless, because it was useless at these ranges.

A lot of cruiser designs are routinely criticised because of a lack of armour. But was this really a problem? Also remember that big parts of the better armoured ships were NOT armoured, which includes many systems crucial for the fighting ability (e.g. for fire control).

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PostPosted: Tue Apr 19, 2016 7:51 am 
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Your argument is becoming circular. It is like saying "I haven't used my insurance, therefore all insurance is a waste". The armor was added for a specific set of circumstances that were considered likely in the coming war. But the war wasn't fought in the way that was expected. There were few daylight gun battles at the predicted ranges. So the armor was not as useful as planned. That doesn't mean it was useless. At Guadalcanal, San Francisco's armor couldn't keep out the 14" shells. But it did keep out the 5", 5.5" and 6" shells, which were the majority of the hits. But since Portland wasn't subjected to the same barrage of shells, her differing armor scheme was not tested. Even still, San Francisco's armor wasn't tested against the 8" shells it was designed to counter since no heavy cruisers opposed her. So did that make it useless? Sometimes utility, like beauty, is in the eye of the beholder.


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PostPosted: Tue Apr 19, 2016 10:48 am 
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If I remember correctly, David K Brown wrote an article years ago in either Warship or Warship International, arguing that British cruisers of WWII would have been better if they had been built without belt armor. His argument was that there was only a very small number of times where the belt armor of a British cruiser defeated a shell (because, in part, there were so few times that the belt armor of a British cruiser was even hit). Therefore, if the belt armor had been omitted and the weight used for additional anti-aircraft, then the ships would have been better suited to the action seen in WWII.


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