Rn vs IJN

[Shortround6]

If you read Lundstrom's 3 volumes on the 1942 airwar (First Team and Black Shoe...) in the Pacific, you'll note that he assessed the 5in/38 as ineffective as an AA weapon. Medium calibre AA, without VT ammo was just too inaccurate, for a variety of reasons. to be of much use against aircraft. It did have a deterrent value, though.

OTOH, the USN BuOrd claimed massive numbers of AA kills in 1942 including many 5in/38 kills but the vast majority of these claims cannot be verified via IJN records.

There was quite a difference between perception and reality.
The US believed they had the best AA suite in the world, they did, it just was nowhere near as good as they thought in combat. A US Destroyers with 5 guns putting 10-12 black puff balls into the sky per minute per barrel (50-60 per ship) was certainly more impressive looking than the amount of puff balls the Japanese destroyers could make and compared to some the UK destroyers with one 4in gun making 10-12 puff balls per ship the deterrence might have been significant.
UK destroyers could put up a number of puff balls over other ships but with 40 degrees of elevation they couldn't do much for themselves.

The real trick was getting those puff balls to actual damage the enemy aircraft.

I may have my own definition of "medium caliber AA"
I tend to call all of the 5in to 3in guns heavy AA which does cover quite a span.
I ignore the over 5in stuff although plenty of navies built high elevating 5.5 to 8in guns (Some British 8in would elevate to 70 degrees?) as their chances were not good due to training issues (training as in actually pointing the guns at the targets) and firing rates. Even Swordfish could cover 2/3 of a mile between shots.
Japanese special AA ammo for 14-16in guns show desire but actual effectiveness???

I call the 55mm and down to about 27/28mm medium AA and the 25mm and under light AA.
The Medium requires more in the way of mounts, deck reinforcement, crew, ammo handling etc.

The US 1.1 (28mm) weighed about 4.7 tons and 6.25 tons per mount. It was never used as a triple, twin or single (unless some enterprising crew welded together their own mount)


The Hotchkiss 25mm is sort of neither fish nor fowl. It could be single mounted on a pintile mount or used in twin/triple mounts with geared elevation and traverse.
It wasn't much more capable than the 20mm Oerlikon overall or even as good. 250gram shell offset by low rate of fire.

 

[Shortround6]

When we went through all the air / sea battles in the Pacific, including I think upthread in this thread, you can see several raids in which the Japanese strike groups were decimated by the USN AAA. Including in 1942.

The British are not going to be able to do than in general unless we carefully pick and choose certain ships in 1942.

On the other hand the Japanese AA is not good enough to decimate British strike groups in 1942 either. This is something of an assumption as there was very little for examples. But the Japanese AA (not aircraft) did not decimate US strike groups.

 

[Wild_Bill_Kelso]

The British are not going to be able to do than in general unless we carefully pick and choose certain ships in 1942.

On the other hand the Japanese AA is not good enough to decimate British strike groups in 1942 either. This is something of an assumption as there was very little for examples. But the Japanese AA (not aircraft) did not decimate US strike groups.

That's true, but they A6M definitely did on a number of occasions, and a Fairey Swordish is not only very short-ranged compared to a D3A, it's very slow and poorly armed and vulnerable compared to an SBD or a TBF.

 

[Shortround6]

That's true, but they A6M definitely did on a number of occasions, and a Fairey Swordish is not only very short-ranged compared to a D3A, it's very slow and poorly armed and vulnerable compared to an SBD or a TBF.

True but if you don't have any (or many) A6Ms around?????

Granted if was March of 1943 but the Battle of the Bismarck sea shows that the Japanese had trouble defending it's ships even with air support at times.
Granted the success of this battle also needed a change in bombing tactics/techniques but with only 2 bombers destroyed out of the 114 used the Japanese AA was not winning any marksmanship medals.

The AA guns should not have been used in place of air cover, they should be used when the air cover fails for whatever reason. The fall back position. The 2nd layer.
Japanese AA was among the world's worst. If the air cover fails the Japanese get the Repulse reversed.

Italians didn't have lot of these and they were not as good as a 40mm Bofors

But twin 37mm automatic water cooled guns? In the 1930s?
It had problems but the Japanese were not even close.

 

[RCAFson]

That's true, but they A6M definitely did on a number of occasions, and a Fairey Swordish is not only very short-ranged compared to a D3A, it's very slow and poorly armed and vulnerable compared to an SBD or a TBF.

The Swordfish would be a rare bird in this alternate history scenario. Albacores and Skua's would be common.

 

[RCAFson]

When we went through all the air / sea battles in the Pacific, including I think upthread in this thread, you can see several raids in which the Japanese strike groups were decimated by the USN AAA. Including in 1942.

Really, only one and that was Santa Cruze, where the killer was massed 20mm along with Bofors (their first appearance) and 1.1in guns. BuOrd, for example, awarded USS South Dakota with 26 AA kills but even her Captain Gatch stated that her 5In guns were responsible for only 5% of the awarded kills (26 was about about a 5-1 overestimate).

 

[Wild_Bill_Kelso]

Are you ever on the level man? Serious question.

 

[Shortround6]

The Swordfish would be a rare bird in this alternate history scenario. Albacores and Skua's would be common.

Skua's would be very uncommon. By the end of 1941 they were being used as target tugs and advanced trainers, none were left in operational combat squadrons after Aug 1941.

 

[Shortround6]

British radar equipment distribution was bit scattered. Ships got radar sometimes depending on where they were and when.

The HMS Frobisher for example had a very long refit (over a year) that finally ended in March of 1942.
She had been equipped with
a Type 281 early-warning radar
a Type 273 surface-search radar
a pair of Type 285 anti-aircraft gunnery radars on the roofs of the newly installed four-inch directors.

She was given no radar for her 7.5in main gun director or for her pom pom directors. At this point she had four quad pop-pom mounts and had seven 20mm Oerlikons.

I am sure there were a number of newer, more modern ships that did not have that extensive a radar suite at that time.
She was used for convoy escort in the Indian ocean for most of 1942 and 1943.

 

[Admiral Beez]

Skua's would be very uncommon. By the end of 1941 they were being used as target tugs and advanced trainers, none were left in operational combat squadrons after Aug 1941.

Too bad. I would have based all available Skuas (and Rocs) at first Singapore and then Ceylon. Provided aircrew could be found, as their original FAA crews would now be in Fulmars and Albacores. Maybe transfer them to the RAF or RAAF?

 

[RCAFson]

Skua's would be very uncommon. By the end of 1941 they were being used as target tugs and advanced trainers, none were left in operational combat squadrons after Aug 1941.

Yes, because they weren't suitable in the ETO, as DBs due to their bomb load and performance. But with no war in the ETO the FAA would probably kept them in service longer (as per the TBD, for example).

 

[Shortround6]

Why?

However good (or bad) the Skua was in the spring of 1940 it was certainly not a good choice 1 1/2 years later.

The Roc is nothing more than a free target for the Japanese, all the practice and none of the expense (fuel, maintenance, cost of feeding the air crew and ground crew),

Swipe a few dozen Tomahawks from North Africa and send them east.

You want to save South East Asia stop sending them scraps swept out of corners of dusty hangers and send them planes that are merely obsolescent and not completely obsolete.

 

[RCAFson]

Are you ever on the level man? Serious question.

An analysis of Santa Cruz will show that autocannon was the by far and away the primary aircraft killer.

 

[Shortround6]

Yes, because they weren't suitable in the ETO, as DBs due to their bomb load and performance. But with no war in the ETO the FAA would probably kept them in service longer (as per the TBD, for example).

They had been planning on replacing the Skua with the Fulmar in 1937-38 which is well before the ETO broke out.
The initial order for 127 Fulmars was placed in 1938.
Does anybody really think that if Germany didn't invade Poland in 1939 the Air ministry would have have told Fairey, "hey, hold up building those 127 Fulmars we ordered, we are going to keep using Skua's till about 1942, we will let you know in year or so to start production or not"

 

[EwenS]

Before the RR Exe engine development was suspended in 1939 forcing a redesign, the Barracuda was scheduled to enter production in April 1941 with the initial order for 250? taking about 12 months. No European war, does the Exe go ahead? Does it encounter development problems pushing back the Barracuda?

And as I've noted previously, the Sept 1939 expectation was that Illustrious, Formidable & Victorious would have completed in 1940, Indomitable in April 1941 (6 months earlier than historical), Implacable in Oct 1941 and Indefatigable in June 1942. Whether the build schedules on the latter pair in a continuing peacetime environment could have achieved those deadlines is anyones guess, but they would not have incorporated some of the changes made to the original design courtesy of war experience.

With no war in Europe the 2,500 tons of armour plate on order from Czechoslovakia for ships under construction, that historically was never delivered due to the outbreak of war, would be received allowing earlier completion. And no I've never seen a statement of which ships would have been affected. Possibly Victorious. Probably some cruisers.

 

[z42]

Before the RR Exe engine development was suspended in 1939 forcing a redesign, the Barracuda was scheduled to enter production in April 1941 with the initial order for 250? taking about 12 months. No European war, does the Exe go ahead? Does it encounter development problems pushing back the Barracuda?

At least in retrospect we can say they should have gone with the Merlin from the get-go and forgot about the Exe. I guess at the time with everything aviation related developing quickly, it would have been disappointing to design an aircraft around an existing engine instead of the promise of a more powerful engine under development.

 

[Admiral Beez]

Why? However good (or bad) the Skua was in the spring of 1940 it was certainly not a good choice 1 1/2 years later

In March/April 1942 the IJN's carrier fleet approached Ceylon without a credible CAP aloft, allowing a strike group of Blenheim bombers to arrive sufficiently unopposed that near misses were scored against the carriers. Swap out those Blenheims for thirty Skuas, diving, unopposed from altitude upon the carriers, and the IJN will have a bad day. That's why.

 

[Peter Gunn]

In March/April 1942 the IJN's carrier fleet approached Ceylon without a credible CAP aloft, allowing a strike group of Blenheim bombers to arrive sufficiently unopposed that near misses were scored against the carriers. Swap out those Blenheims for thirty Skuas, diving, unopposed from altitude upon the carriers, and the IJN will have a bad day. That's why.

I agree, also, I know I've said this before, probably even in this thread but the IJN could have gotten quite a shellacking (not sure about a Midway level whacking but a good punch nonetheless) had the RN managed the night torpedo attack there were preparing for:

Armoured Aircraft Carriers

Just two months before the decisive battle of Midway, the Indian Ocean was the scene of Operation C - a face-down between the fleets of Britain and Japan during the Battle of Ceylon. Their carrier forces came within just 100 miles of a clash that could have changed the course of the war.

www.armouredcarriers.com

 

[Peter Gunn]

In regards to S Shortround6 black puff balls (I agree with everything you said BTW) was that while the 5"/38 may not have been tremendously accurate, there must have been a certain deterrent effect on IJN pilots. Seeing hundreds of those black puff balls between me an the target would make me think twice about meeting my ancestors so soon.

 

[Admiral Beez]

I agree, also, I know I've said this before, probably even in this thread but the IJN could have gotten quite a shellacking (not sure about a Midway level whacking but a good punch nonetheless) had the RN managed the night torpedo attack there were preparing for:

Coral Sea and Midway would have been different affairs (if at all) if the IJN was down two or three carriers for repairs or replacement.