Rn vs IJN

EwenS · Oct 18, 2023

Glider said:
Its also worth remembering that a good number of the early RN light cruisers were being rearmed as AA cruisers with multiple 4in AA guns and modern LAA. A much better use for them than trying to pretend that they could still operate on the front line going toe to toe with other warships. In the Pacific where aircraft were so important this would only have increased their value.
In this role they performed well. IIRC, the RN vessel that was credited with the most aircraft kills during the war, was one of those converted light cruisers.

There were 6 converted 1936-1940. 2 had been lost by the outbreak of war with Japan with another 3 lost in 1942.

Coventry & Curlew were rearmed in 1936/37 as a reaction to the experience of the Med Fleet during the Abyssinian Crisis at the end of 1935. They lost all their 6" guns and TT. They gained 10 single 4" being removed from other cruisers being modernised at the time, controlled by 2 HACS Mk.III. They also had by 1939 one octuple pom-pom and 2 quad 0.5".

After that there were plans to convert more that at one point extended to the remaining 11 C class (with 4 twin 4" one quad pom-pom & 2 quad 0.5") and 8 D class (with 4 twin 4.5" + light AA). In the end only 4 other C class were taken in hand for conversion (Cairo, Carlisle, Curacao & Calcutta) before the outbreak of WW2 caused cancellation of the rest of the programme. Money was the reason for the delay, there being more important uses for the availble funds.

The next step was interest in the US 5"/38 and Mark 37 director in late 1940. Delhi was converted in the USA under Lend Lease from April 1941, returning to the fleet in early 1942. A second conversion was cancelled on US entry to the war.

Finally in mid-1942, after a number of the C class had already been lost Colombo & Caledon were taken in hand for conversion with 3 twin 4", 2 twin Hazemeyer Bofors and 6 twin 20mm. They didn't emerge until March and Dec 1943. Given the strains on British shipyards at the time, the resources expended on these two ships could have been better deployed elsewhere.

These ships lacked range for operations in the open waters of the Pacific.

Wild_Bill_Kelso · Oct 18, 2023

EwenS said:
Lets be careful about the effectiveness of US AA fire in the early part of the war as it is usually overstated and studies later in the war caused massive downward revisions of the claims made for it especially 5" claims before the arrival of proximity fuzes in early 1943.

The US went to war in Dec 1941 with most of its ships equipped with 5"/25 or 5"/38 guns in single or twin mounts and a few quad 1.1" mounts on larger vessels and single 0.5" MG.

The 20mm Oerlikon was only selected in Nov 1940, production started in June 1941 and only 379 had been produced by Pearl Harbor with another 30,000+ following in 1942, out of an eventual total of nearly 125,000. So they were only beginning to appear in the Fleet in Dec 1941. It was 1943 before this weapon received a gyro gunsight.

The pilot of the twin 40mm Bofors Mk 1 wasn't produced until Jan 1942 with the first fit in an operational ship in July 1942 (destroyer Coghlan DD-606). But only 503 were produced in 1942 (nearly half in Nov-Dec) from a wartime total of 9,325.

The pilot of the quad 40mm Bofors Mk 2 was produced in April 1942. Only 212 were produced in 1942.

Just by way of example look at the carrier Enterprise. She began the war with 8x5"/38 in single mounts, 2 quad 1.1" and 24x 0.5" MG. By Midway the 0.5" were gone to be replaced by 32 single 20mm. The quad 1.1" were replaced with quad Bofors in Nov 1942 and the Oerlikons increased to 46. Compare that with her end of war outfit after her May-Sept 1945 refit when she had the 8x5"/38 plus 11 quad and 5 twin Bofors and 16 twin 20mm.

Weren't the 5"/38 a lot better than the 4.5" DP?

EwenS said:
And as for directors, the latest Mark 37 was installed in very few ships in the Pacific in 1942. Older types proved little more effective than RN systems. And ships manoevering at high speeds simply increased the inaccuracy of their AA fire. 5" fire was found to have little more than a harrasing effect beyond 12,000 yards. Fuzes proved unreliable when attempting to counter dive bombers.

They had the Mark 37 on even the smaller ships, pretty early in the war. For example

Sims class destroyers (12 ships, AA 4 x 5"/38, 8 x .50 cal)
Gleaves class destoryers (66 ships from 1940, AA 5 x 5"/38, 6 x .50 cal, later 4 x 40mm Bofors, 7 x 20mm Oerlikon)
Fletcher class destroyers (175 ships from June 1942), along with the pretty good 5"/ 38 guns, a twin Bofors 40mm and 6 or 7 Oerlikon 20mm by mid-1942.

Thumpalumpacus · Oct 18, 2023

EwenS said:
Lets be careful about the effectiveness of US AA fire in the early part of the war as it is usually overstated and studies later in the war caused massive downward revisions of the claims made for it especially 5" claims before the arrival of proximity fuzes in early 1943.

The Japanese pilots at Santa Cruz recovered to their carriers literally stunned by American AA -- in Oct 1942, only ten months into our war. This is according to Jon Parshall, among many other historians.

So while American AA was no great shakes for most of that year, we'd already started tacking on barrels anywhere we could stuff them. Look at Enterprise's after-action reports from both Eastern Solomons and Santa Cruz; the author literally suggested that they remove some armor from Big E in order to free up topweight for more 40mms.

So yes, early war American AA was sketchy, but well before the proximity fuse it was already shocking the Japanese.

Admiral Beez · Oct 18, 2023

don4331 said:
p.s. You can find wander information for most of IJN WWII torpedoes on the Navweaps site

Damn you and your solid source material. Our resident contrarians are not going to like you. The Navweaps site is a fantastic reference and place to bury oneself over a coffee.

Wild_Bill_Kelso said:
Could you put a Miles M.20 on a carrier or is it too fragile?

Miles M.20 - Wikipedia

en.wikipedia.org

"A second prototype, U-0228 (later DR616) was built to Specification N.1/41 for a Fleet Air Arm shipboard fighter, equipped with an arrestor hook and catapult launch points. It first flew on 8 April 1941. Test pilot Eric Brown flew this aircraft in January 1942. He reported that "although surprisingly nippy in performance, could not match the Martlet, Hurricane, or Spitfire in manoeuvrability". It lacked also the excellent deck landing characteristics of the Martlet."

Wild_Bill_Kelso · Oct 18, 2023

Admiral Beez said:
Damn you and your solid source material. Our resident contrarians are not going to like you. The Navweaps site is a fantastic reference and place to bury oneself over a coffee.

Miles M.20 - Wikipedia

en.wikipedia.org

"A second prototype, U-0228 (later DR616) was built to Specification N.1/41 for a Fleet Air Arm shipboard fighter, equipped with an arrestor hook and catapult launch points. It first flew on 8 April 1941. Test pilot Eric Brown flew this aircraft in January 1942. He reported that "although surprisingly nippy in performance, could not match the Martlet, Hurricane, or Spitfire in manoeuvrability". It lacked also the excellent deck landing characteristics of the Martlet."

Fascinating! So maybe it could have been viable. I'm sure they could put a bomb on it...

EwenS · Oct 18, 2023

Wild_Bill_Kelso said:
Weren't the 5"/38 a lot better than the 4.5" DP?

Their performance of the guns themselves were pretty much the same. The difference was in the mounts, especially the base ring mounts for the 5"/38 with their integral hoists to increase the rate of fire.

United Kingdom / Britain 4.5"/45 (11.4 cm) QF Marks I, III and IV - NavWeaps

www.navweaps.com

USA 5"/38 (12.7 cm) Mark 12 - NavWeaps

www.navweaps.com

Wild_Bill_Kelso said:
They had the Mark 37 on even the smaller ships, pretty early in the war. For example

Sims class destroyers (12 ships, AA 4 x 5"/38, 8 x .50 cal)
Gleaves class destoryers (66 ships from 1940, AA 5 x 5"/38, 6 x .50 cal, later 4 x 40mm Bofors, 7 x 20mm Oerlikon)
Fletcher class destroyers (175 ships from June 1942), along with the pretty good 5"/ 38 guns, a twin Bofors 40mm and 6 or 7 Oerlikon 20mm by mid-1942.

Sims class
Desron 2 with 9 of the 12 Sims class transferred to the Pacific after Pearl Harbor. The other 3 remained in the Atlantic as leaders of Desrons 8, 11 & 13.

Benson - Gleaves classes
Desrons 12 (4 early 1941 completions transferred to Pacific in early 1942. Remaining 10 ships completed March-May 1942), 14 (8 ships commissioned mid-1942), 18 (9 ships completed Dec 1942-July1943), 19 (8 ships completed Sept 1942-Aug 1943). The remaining ships of these classes stayed in the Atlantic / Med until much later in the war.

Fletcher class
The first of these didn't complete until June 1942 with only 25 completing before the end of 1942. While virtually all the Fletchers went to the Pacific immediately after completion and work up in the Atlantic, the first of them weren't showing up until about Oct 1942.

Most of the destroyers with the Pacific Fleet in Dec 1941 came from the "Goldplater" classes built in the 1930s. So not as many destroyers with Mark 37 directors on the front line in the Pacific as you might think.

Plenty of info on US destroyers here

https://destroyerhistory.org/destroyers/introduction/

Shortround6 · Oct 18, 2023

EwenS said:
The US went to war in Dec 1941 with most of its ships equipped with 5"/25 or 5"/38 guns in single or twin mounts and a few quad 1.1" mounts on larger vessels and single 0.5" MG.

This is quite true, None of the set ups were good. Unfortunately there is/was no good way of measuring how well the AA fire degraded the accuracy of the attackers instead of shooting them down. The US 5in guns could put more shell bursts into the air in a given time period than the Japanese 5in guns.
The British 4in AA guns (cruiser AA) made a smaller burst, I have no idea if the pilots could see the difference but the 4in guns are rated at 15-20rpm while the Japanese 5in/40s (heavy cruiser AA guns) fired at 8-14rpm. The Japanese light cruisers

were built with 2-3 8cm (3in or 3.1) guns and a lot of them traded the 8cm guns for a pair of 25mm guns. One paired 25mm replacing each 8cm gun.
They were built with 2-4 6.5mm machine guns and these got changed out for 2-8 13mm guns depending on ship/class/date of refit. So we can say that the Japanese AA armament was pretty dismal. It was pretty much 1943 before the Japanese started yanking the 5.5in guns and/or torpedoes in order to beef up the AA with more than few extra 25mm guns.
A number of the modern RN light cruisers got 2 quad 2pdr pom-poms in 1940-41 and a smattering of quad .5 in guns. Isolated 20mm guns were showing up in 1941.
The Southhamptons and newer were built with two quad pom-poms, and perhaps some .5in mgs? 1940-41 additions?
Belfast and Endinburgh were practically battleships in late 1939 although that was not enough in 1942 and later.
We could argue quite awhile about the British 2pdr and the US 1.1 but the Japanese 25mm was neither.
None of the 12.7-13.2 machine guns were much good, Japanese was the worst.

EwenS said:
And ships manoevering at high speeds simply increased the inaccuracy of their AA fire.

Or one could say that trying to use the AA guns interfered with the ships ability to maneuver

Sometimes took a while for that concept to sink into gunnery trained officers.

EwenS · Oct 18, 2023

Wild_Bill_Kelso said:
were there any say maybe obscure cancelled designs I never heard of which could have been developed into a better carrier strike aircraft (and just... aircraft) than a Skua but with better speed and range than an Albacore or a Swordfish? Could you put a Miles M.20 on a carrier or is it too fragile?

There was perhaps an opportunity for hsitory to have taken an alternate route around 1937 when the Spec was issued for a Swordfish replacement. Fairey submitted designs for both a monoplane & biplane aircraft. The Air Ministry / Admiralty preferred the latter at the end of the day. One thing that went against the monoplane was its low wing design which was deemed to obstruct the Observers view. So just a year later when the Spec for the Albacore's replacement was issued, all the designs (Fairey & Supermarine which turned into hardware as well as Blackburn, Bristol etc) moved to design high wing monoplanes.

So just possibly we might have had a high wing monoplane TBR design entering service in 1940 (when the Albacore did) if there was some better understanding of the requirements on both sides of the purchasing equation. Then of course you need to find an engine better than the Taurus to hopefully boost the performance further..

RCAFson · Oct 18, 2023

Shortround6 said:
going back to "kit" the British and Japanese have a real disparity in light cruisers.

They both have a bunch of WW I left overs (although the Japanese built many of theirs in the 20s.)
British built a bunch of 6in armed cruisers (22 before 1940) after they build their quota of 8in cruisers, Japanese build 4 and then swap the turrets to twin 8in leaving them with NO light cruisers with 6in guns that use turrets/enclosed gun houses until 1942.

A lot depends on the British war losses in this hypothetical but the Japanese are at a real disadvantage in in the cruiser catagory. Unlike the Americans, all British cruisers have at least some torpedoes early in the war so again, the British are not a plug in replacement for the Americans. Different weapons, different doctrine, different tactics.

BTW just about all British cruisers newer than the E class (1921-22) have four twin 4in AA guns by the time WW II starts. Only the Japanese heavy cruisers have four twin heavy AA guns. (slow firing 5in). All of their light cruisers had crap for heavy AA. Kind of even things up a bit for the British, won't stop the IJN aircraft but the British have better AA to go against the Japanese planes while the Japanese have crap AA to go against the British aircraft. Both are worse than American AA even before proximity fuses.

It was the close range AA that did most of the killing and the early war RN close range AA was superior to USN close range AA until late 1942.

RCAFson · Oct 18, 2023

Thumpalumpacus said:
The Japanese pilots at Santa Cruz recovered to their carriers literally stunned by American AA -- in Oct 1942, only ten months into our war. This is according to Jon Parshall, among many other historians.

So while American AA was no great shakes for most of that year, we'd already started tacking on barrels anywhere we could stuff them. Look at Enterprise's after-action reports from both Eastern Solomons and Santa Cruz; the author literally suggested that they remove some armor from Big E in order to free up topweight for more 40mms.

So yes, early war American AA was sketchy, but well before the proximity fuse it was already shocking the Japanese.

One of the historical issues that we have when looking at RN AA, was that it was usually dispersed around a large convoy, rather than being focused around a carrier. The USN knew that their carriers would be the focal point of any aerial attack, whereas the RN typically had to protect a convoy and any escorting carriers

Glider · Oct 18, 2023

An interesting example of how the AA guns on warships developed as the war progressed is HMS Belfast

1939
16 x 2pd (2 x 8) 8 x 0.5in (2 x 4)

Dec 1942
16 x 2pd (2 x 8) 14 x 20mm (3 x 2 on Mk XX mounting, 2 x 2 on Mk V mounting, 4 x 1)

March 1944
32 x 2pd (2 x 8, 4 x 4) 14 x 20mm (2 x 2 on Mk XX mounting, 2 x 2 on Mk V mounting, 6 x 1)

Sept 1944
36 x 2pd (2 x 8, 4 x 4, 4 x 1) 14 x 20mm (2 x 2 on Mk XX mounting, 2 x 2 on Mk V mounting, 6 x 1)

Aug 1945
36 x 2pd (2 x 8, 2 x 4, 4 x 1), 5 x 40mm (2 x 1 on Mk 1 mounting, 3 x 1 Boffin Mounting, 8 x 20mm ( 2 x 2 on Mk V mounting, 4 x 1)

here are many example in every WW2 navy but I found looking at the development on one ship interesting

Admiral Beez · Oct 18, 2023

Wild_Bill_Kelso said:
Fascinating! So maybe it could have been viable. I'm sure they could put a bomb on it...

The Miles M.20 naval variant was too late though, as it would have entered service at the same time as the Martlet, Seafire and Sea Hurricane. Instead we need the M.20 to arrive before the Fulmar.

Glider · Oct 18, 2023

The numbers and types of aircraft carried understandably changed as the war progressed. The following are snapshots of the aircraft carried by the Illustrious whose nominal number of aircraft was 36. Its interesting that apart from the early months of the war, she always carried a lot more than 36

Sept 1940
15 x Fulmars, 18 x Swordfish

May 42
20 x Martlets, 20 x Swordfish

Sept 43
28 x Martlets, 10 x Seafires, 10 x Barracuda

May 44
28 x Corsairs, 21 x Avengers

March 45
36 x Corsairs, 16 Avengers

Shortround6 · Oct 18, 2023

Glider said:
An interesting example of how the AA guns on warships developed as the war progressed is HMS Belfast

1939
16 x 2pd (2 x 8) 8 x 0.5in (2 x 4)

Dec 1942
16 x 2pd (2 x 8) 14 x 20mm (3 x 2 on Mk XX mounting, 2 x 2 on Mk V mounting, 4 x 1)

March 1944
32 x 2pd (2 x 8, 4 x 4) 14 x 20mm (2 x 2 on Mk XX mounting, 2 x 2 on Mk V mounting, 6 x 1)

Sept 1944
36 x 2pd (2 x 8, 4 x 4, 4 x 1) 14 x 20mm (2 x 2 on Mk XX mounting, 2 x 2 on Mk V mounting, 6 x 1)

Aug 1945
36 x 2pd (2 x 8, 2 x 4, 4 x 1), 5 x 40mm (2 x 1 on Mk 1 mounting, 3 x 1 Boffin Mounting, 8 x 20mm ( 2 x 2 on Mk V mounting, 4 x 1)

here are many example in every WW2 navy but I found looking at the development on one ship interesting

It is but we should remember that the Belfast was out of action due to the mine from the end of 1939 until the end of 1942 and the Belfast had bulges fitted to strengthen the hull which also increased stability and the ability to carry a large amount of AA guns.
Many British ships got a sprinkling of light AA guns even in 1940 -41, largely restricted by the 20mm and 40mm factories beginning production. They could not get what they wanted.

The 2pdr was a bit of an odd weapon. It was one of the few light AA guns that was both fast firing (if we can consider 115rpm fast) that would also knock down most single engine aircraft with a single hit (unless the pilot was very, very lucky) The German 37 was not fast firing. The US 1.1 needed several hits as did the Japanese/French 25mm. The 40mm Bofors would but it was only in service with the Dutch Navy in any numbers in 1940 and sure isn't saying much.

Shortround6 · Oct 18, 2023

Admiral Beez said:
The Miles M.20 naval variant was too late though, as it would have entered service at the same time as the Martlet, Seafire and Sea Hurricane. Instead we need the M.20 to arrive before the Fulmar.

Might want to look at the Miles and it's landing speed again.
Maybe the US could have used it. The Spitfire would have looked like an absolutely perfect carrier plane in comparison.
The thing had too high a landing/stalling speed.
Accident/write off rate would have been horrendous.

z42 · Oct 18, 2023

Shortround6 said:
The German 37 was not fast firing.

The Flak 37/43 was decent. Though by the time it was introduced into service it was too late.

RCAFson · Oct 18, 2023

Glider said:
The numbers and types of aircraft carried understandably changed as the war progressed. The following are snapshots of the aircraft carried by the Illustrious whose nominal number of aircraft was 36. Its interesting that apart from the early months of the war, she always carried a lot more than 36

Sept 1940
15 x Fulmars, 18 x Swordfish

May 42
20 x Martlets, 20 x Swordfish

Sept 43
28 x Martlets, 10 x Seafires, 10 x Barracuda

May 44
28 x Corsairs, 21 x Avengers

March 45
36 x Corsairs, 16 Avengers

Some more numbers:

5 May 1942; 25 Martlets, 1 night-fighting Fulmar and 21 Swordfish (data from Illustrious action report).
10 Sept 1942: six Fulmars, 23 Martlets, and 18 Swordfish. ("")
22 June 1944; 42 Corsairs, 15 Barracudas (Warship profile 11)

Wild_Bill_Kelso · Oct 18, 2023

Shortround6 said:
Might want to look at the Miles and it's landing speed again.
Maybe the US could have used it. The Spitfire would have looked like an absolutely perfect carrier plane in comparison.
The thing had too high a landing/stalling speed.
Accident/write off rate would have been horrendous.

Worse than a Corsair?

EwenS · Oct 18, 2023

According to my sources this is not entirely accurate.

Glider said:
An interesting example of how the AA guns on warships developed as the war progressed is HMS Belfast

1939
16 x 2pd (2 x 8) 8 x 0.5in (2 x 4)

Dec 1942
16 x 2pd (2 x 8) 14 x 20mm (3 x 2 on Mk XX mounting, 2 x 2 on Mk V mounting, 4 x 1)

AIUI the twins were all powered Mk.V mounts

Another 4 single 20mm were added at Rosyth in June 1943.

Glider said:
March 1944
32 x 2pd (2 x 8, 4 x 4) 14 x 20mm (2 x 2 on Mk XX mounting, 2 x 2 on Mk V mounting, 6 x 1)

The next change in April/May1944 saw one twin 20mm removed (from the top of B turret) and 6 singles added over the June 1943 fit. There were no extra pom-poms added at this time. That was how she appeared off Normandy on D-Day.

Glider said:
Sept 1944
36 x 2pd (2 x 8, 4 x 4, 4 x 1) 14 x 20mm (2 x 2 on Mk XX mounting, 2 x 2 on Mk V mounting, 6 x 1)

Aug 1945
36 x 2pd (2 x 8, 2 x 4, 4 x 1), 5 x 40mm (2 x 1 on Mk 1 mounting, 3 x 1 Boffin Mounting, 8 x 20mm ( 2 x 2 on Mk V mounting, 4 x 1)

The next change took place during her extensive refit on the Tyne between 4 Aug 1944 and 8 May 1945 to ready her for service in the Pacific.

At that point she lost the after pair of twin 4" mounts and emerged with the light that you note
2 octuple, 4 quad pom-pom and 4 single powered pom pom.
4 twin Mk.V 20mm and 6 singles

Then at Sydney at the beginning of Aug 1945, two of the twin 20mm were upgraded to single 40mm Boffins, two of the single 20mm were replaced with single 40mm Mk.III Bofors with another Mk.III put onto the roof of B turret.

Detail extracted from
Raven & Roberts "British Cruisers of World War 2"
"Man O' War 5 Town Class Cruisers" by the same authors
"British Town Class Cruisers" by Conrad Waters.
Study of many photographs.

It is true that all cruisers saw incremental upgrades to their light AA throughout the war, with the first sacrifice being aircraft and catapults. But major changes were made from late 1943 mostly to prepare ships for operation in the Far East and Pacific. Main armament turrets were being sacrificed for more light AA and radar. Belfast and HMAS Hobart were unusual in that they had sufficient reserves of stability to keep all 4 main turrets and still have major upgrades to their light AA (as noted Belfast lost 2 twin 4" instead).

Admiral Beez · Oct 18, 2023

RCAFson said:
22 June 1944; 42 Corsairs, 15 Barracudas (Warship profile 11)

This is about the time where a RN CBG equipped with radar, CICs and experienced fighter director officers (FDOs), can match any thus-far surviving IJN CBG, presumably equipped with the A6M5 along with a mix of D4Y, B6N, or B7A).

Any chances for IJN and RN carriers to meet in battle 1943-45?

Was there any instances where the IJN and RN carriers could have encountered each other in 1943 to 45? I'd like to see how a RN AFD carrier equipped with radar, single-seat fighters (Seafire, Martlet, Hellcat or Corsair) and modern strike aircraft (Tarpon or Barracuda) would perform against a...

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