The Anniversary of The Channel Dash - 1942 - and the wider RN Fleet Air Arm during the Second World War

Mölders 1

War Hero
One of the classic "get your measures of effect" right was AA defence of merchantmen on the Malta run in 1941-2.

With "not enough" AA guns to go around, one argument was to concentrate them on "flak ships" where a battery of guns, with better fire control and better-trained crews, would be significantly more lethal to attacking aircraft than scattered weapons fired in local control by scared DEMS gunners could be.

This was winning the day - shooting down enemy bombers is good, right?.

Until someone checked the statistics to date, and noted that 25% of unarmed ships attacked by aircraft were sunk or badly damaged: while armed ships (even if just a couple of 3" AA guns and some Lewis or Hotchkiss machine-guns) only had a 10% rate of "lost/badly damaged".

"Shooting back" - even if not very effective at bringing down the bombers - still made a big difference to a ship's survival and their ability to reach their destination; was the mission "shoot down a few Luftwaffe/Regia Aeronautica bombers" or was it "get cargo to Valetta"?

Air defence against manned aircraft - like ASW - is not about destroying the enemy (it's a bonus if you can do that, but it's not the point). The enemy is trying to stop you doing something (evacuating troops, transporting cargo, invading them...) - if you achieve that despite their efforts, you win even if every one of their bombers or U-boats returns home undamaged. If they slaughter the convoy, it's no consolation to point out that you did shoot down half-a-dozen aircraft while they did it...
This is very good but.....this doctrine went out of the window in the Pacific during the last year of the Pacific War when the Japanese started using Kamikaze Suicidal Tactics.

The only real defence against them was to shoot them down/destroy them completely, driving them off was NOT an option.

This in turn brings us back nicely to the argument about Armoured Vs Wooden Flight Decks fitted to Allied Aircraft Carriers......
 

Yokel

LE
This is very good but.....this doctrine went out of the window in the Pacific during the last year of the Pacific War when the Japanese started using Kamikaze Suicidal Tactics.

The only real defence against them was to shoot them down/destroy them completely, driving them off was NOT an option.

This in turn brings us back nicely to the argument about Armoured Vs Wooden Flight Decks fitted to Allied Aircraft Carriers......

Yes but we were talking about the early years of the war in the European/Atlantic theatre, not when the fanatics at helm of Imperial Japan decided to use expensive aircraft and scare pilots as anti ship missiles.

I was also talking about the days before naval fighters could be radar controlled.
 

jrwlynch

LE
Book Reviewer
Was the 40mm Pom Pom really an effective A.A. Gun......?

Very much so, yes.

From what l have learned it was Maintenance Intensive/Prone To Jamming,

HMS Illustrious managed to get through about 30,000 rounds of 2pdr ammunition in a short period when under very heavy air attack in the Mediterranean (January 1941), her five octuple pom-poms expending their full loads (154 rounds per gun) in each of multiple attacks without jams or stoppages.

fired a low velocity shell which contained only a fairly small amount of H.E.

The original 1931 design had a muzzle velocity of 2040fps, which was seen as becoming inadequate as aircraft speeds rose; this was increased to 2,400fps by the time the war broke out.

The shell was a 2-pound (surprise!) 40mm projectile - reduced slightly to 1.8lb for higher velocity - with a contact fuze and HE filling. If that was inadequate, then so was the near-identical 40mm Bofors..

it's great strength was it's high rate of fire. The latter 40mm Bofors and it's variants were much superior A.A. Weapons.....the U.S. Navy just couldn't fit enough of them to it's Warships during the last year of the Pacific War.

The Bofors was - being a decade newer - higher-performing, but it didn't even begin to be fitted to warships until halfway through the war (the USN's first trials fit was in mid-1942) and demand outstripped supply such that US destroyers were commissioning well into 1944 with empty gun tubs or 20mm mounts where their Bofors were meant to have been. (30,000 rounds of 2pdr pom-pom fire has more deterrent/protective effect than no rounds of 40mm Bofors...) Similarly, many pre-war US ships were forced to keep their heavy, unreliable 1.1" AA quadruple mounts as "better than nothing" while waiting for Bofors production to catch up to demand.

Interestingly, the Bofors was considered superior against torpedo-bombers, but the 2pdr was assessed as equivalent against dive-bombers and kamikazes (Campbell, Naval Weapons of WW2), with the 2pdr getting a second lease of life late-war for the British Pacific Fleet.
 

jrwlynch

LE
Book Reviewer
This is very good but.....this doctrine went out of the window in the Pacific during the last year of the Pacific War when the Japanese started using Kamikaze Suicidal Tactics.

At which point the 20mm Oerlikon became ineffective ("when the 20s open up, it's time to hit the deck", the 40mm Bofors somewhat marginal, and a crash programme to replace 40mm guns with 3"/50 weapons firing VT-fuzed shell was undertaken (giving more chance to inflict lethal damage, far enough out to avoid being hit).

But, that's a very different problem to that faced in 1940-41.
 

Mölders 1

War Hero
Very much so, yes.



HMS Illustrious managed to get through about 30,000 rounds of 2pdr ammunition in a short period when under very heavy air attack in the Mediterranean (January 1941), her five octuple pom-poms expending their full loads (154 rounds per gun) in each of multiple attacks without jams or stoppages.



The original 1931 design had a muzzle velocity of 2040fps, which was seen as becoming inadequate as aircraft speeds rose; this was increased to 2,400fps by the time the war broke out.

The shell was a 2-pound (surprise!) 40mm projectile - reduced slightly to 1.8lb for higher velocity - with a contact fuze and HE filling. If that was inadequate, then so was the near-identical 40mm Bofors..



The Bofors was - being a decade newer - higher-performing, but it didn't even begin to be fitted to warships until halfway through the war (the USN's first trials fit was in mid-1942) and demand outstripped supply such that US destroyers were commissioning well into 1944 with empty gun tubs or 20mm mounts where their Bofors were meant to have been. (30,000 rounds of 2pdr pom-pom fire has more deterrent/protective effect than no rounds of 40mm Bofors...) Similarly, many pre-war US ships were forced to keep their heavy, unreliable 1.1" AA quadruple mounts as "better than nothing" while waiting for Bofors production to catch up to demand.

Interestingly, the Bofors was considered superior against torpedo-bombers, but the 2pdr was assessed as equivalent against dive-bombers and kamikazes (Campbell, Naval Weapons of WW2), with the 2pdr getting a second lease of life late-war for the British Pacific Fleet.
I got my information from navweaps.com amongst other sources.
 

Mölders 1

War Hero
Yes but we were talking about the early years of the war in the European/Atlantic theatre, not when the fanatics at helm of Imperial Japan decided to use expensive aircraft and scare pilots as anti ship missiles.

I was also talking about the days before naval fighters could be radar controlled.

My point is @Yokel that the tactics used by Attacking Aircraft was constantly evolving throughout the war culminating in the Germans using Guided Bombs and the Japanese using Kamikaze tactics.
 

jrwlynch

LE
Book Reviewer
I got my information from navweaps.com amongst other sources.

Worth going a bit wider - Navweaps aren't a bad repository but they're run by a group of US battleship enthusiasts.

One of the better single references is Campbell's "Naval Weapons of WW2", and Norman Friedman has been excellent down the years (both producing good stuff, and showing his references and workings) - his "Naval Anti-Aircraft Guns and Gunnery" gets into not only what was done, but why.
 
Which was reasonably effective against level bombers... which, it turned out, weren't much of a threat to ships. (Even on land, firing from stable concrete platforms and aimed by tachymetric fire control, 1940-41 heavy AA guns still needed ~3,000 rounds per enemy aircraft destroyed - for a five-gun US destroyer that's a half-hour barrage!)

The bigger problem turned out to be dive- and torpedo-bombers, which really needed automatic cannon to counter them. Hence why British destroyers had quadruple 40mm guns (octuples on larger ships) while US destroyers - as late as 1941 - had nothing between their 5" guns and a few .50" machine guns (a few destroyer-leaders had a 1.1" 'Chicago Piano' but that was too unreliable to help much)
Mk 37 was of course made much more effective against dive bombers and torpedo planes with radar and VT, to the point where it by the end of the war it out performing the 40mm, particularly since you had to kill kamikazes rather than just deter them. What is interesting is that the VT fuze was a failure in British Pacific Fleet service due to the inability of their fire control systems to get the round close enough to the target.

I realize this is outside the date range of the thread but it does illustrate how the decisions the RN made regarding AA between the wars handicapped them through out WWII.
 
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Worth going a bit wider - Navweaps aren't a bad repository but they're run by a group of US battleship enthusiasts.

One of the better single references is Campbell's "Naval Weapons of WW2", and Norman Friedman has been excellent down the years (both producing good stuff, and showing his references and workings) - his "Naval Anti-Aircraft Guns and Gunnery" gets into not only what was done, but why.
Friedman is the go to person for both WWII surface and WWII gunnery. Flak: German Anti-Aircraft Defenses, 1914-1945 by Westermann is also an excellent book.

Amazon product
 

Mölders 1

War Hero
Worth going a bit wider - Navweaps aren't a bad repository but they're run by a group of US battleship enthusiasts.

One of the better single references is Campbell's "Naval Weapons of WW2", and Norman Friedman has been excellent down the years (both producing good stuff, and showing his references and workings) - his "Naval Anti-Aircraft Guns and Gunnery" gets into not only what was done, but why.
Understood And Thank you.
 

Mölders 1

War Hero
I realize this is outside the date range of the thread but it does illustrate how the decisions the RN made regarding AA between the wars handicapped them through out WWII.

That is pretty much what l suspected as regards the 40mm Pom Pom Gun. I fear it was unable to cope with the performance of the improved Aircraft designs that appeared as the war (in various theatres of operations) progressed.
 
That is pretty much what l suspected as regards the 40mm Pom Pom Gun. I fear it was unable to cope with the performance of the improved Aircraft designs that appeared as the war (in various theatres of operations) progressed.
Kamikaze attacks stretched US AA systems to the max, to the point the USN was using MK 51 directors to control individual 5" guns because the Mk 37 didn't have enough fire control channels to deal with mass attacks.
 

Mölders 1

War Hero
Kamikaze attacks stretched US AA systems to the max, to the point the USN was using MK 51 directors to control individual 5" guns because the Mk 37 didn't have enough fire control channels to deal with mass attacks.
I see.

However the best defence against Kamikazes were the Fighters of the Combat Air Patrol.
 

Yokel

LE
My point is @Yokel that the tactics used by Attacking Aircraft was constantly evolving throughout the war culminating in the Germans using Guided Bombs and the Japanese using Kamikaze tactics.

As were defensive tactics and technology. The German stand off guided bombs could be defeated by engaging the aircraft that carried them or interrupting the radio links between aircraft and weapon. The anti Kamikaze tactics are not too dissimilar to modern tactics against air launched missile.

My simple point was that early in the war carrier borne fighters intercepted and may have achieved few kills, but contributed to the survival of our ships.

Kamikaze attacks stretched US AA systems to the max, to the point the USN was using MK 51 directors to control individual 5" guns because the Mk 37 didn't have enough fire control channels to deal with mass attacks.

Hence the use of destroyers as radar pickets, fighters to intercept, the first AEW project (Project Cadillac) and so on.
 
I see.

However the best defence against Kamikazes were the Fighters of the Combat Air Patrol.
Correct - the USN estimates 60% of kills were by fighters. Of the AA kills, 60% were shot down by screening ships, with the remainder by the target ships.
 

Mölders 1

War Hero
As were defensive tactics and technology. The German stand off guided bombs could be defeated by engaging the aircraft that carried them or interrupting the radio links between aircraft and weapon. The anti Kamikaze tactics are not too dissimilar to modern tactics against air launched missile.

My simple point was that early in the war carrier borne fighters intercepted and may have achieved few kills, but contributed to the survival of our ships.



Hence the use of destroyers as radar pickets, fighters to intercept, the first AEW project (Project Cadillac) and so on.
I totally agreed with you on the first of your comment.....as l say being "Driven Off" without being able to launch an effective attack is an effective defensive measure.

Loads of Axis Aircraft in both the Mediterranean and Pacific Theatres were unable to launch effective attacks yet were able to escape.

A notable example would be the U.S.S. Enterprise at Santa Cruz, which despite the Japanese Torpedo Bombers evading the C.A.P. Fighters and intensive A.A. were still unable to Torpedo her due to skillful Evasive Manoeuvring by her Skipper.
 

Yokel

LE
Just in case it is of interest, I once stated a thread about WW2 aviation from ships other than carriers - such as Swordfish equipped with floats and operated from battleships, spotter aircraft flown from cruisers, and German and Italian aircraft operated from major warships and surface raiders.

Really they were a relic of the past, and rendered obsolete by the increased availability of carriers, for the allies anyway.
 

Mölders 1

War Hero
Just in case it is of interest, I once stated a thread about WW2 aviation from ships other than carriers - such as Swordfish equipped with floats and operated from battleships, spotter aircraft flown from cruisers, and German and Italian aircraft operated from major warships and surface raiders.

Really they were a relic of the past, and rendered obsolete by the increased availability of carriers, for the allies anyway.

I believe such Spotter Planes were used in the Pacific to direct Shore Bombardments from Warships and were at times used to rescue downed Aircrews.

As far as l know the Japanese (lacking American Radar Guided Fire Control) used theirs throughout the war, the almighty Yamato Class Battleships carried several of them.
 
I believe such Spotter Planes were used in the Pacific to direct Shore Bombardments from Warships and were at times used to rescue downed Aircrews.

As far as l know the Japanese (lacking American Radar Guided Fire Control) used theirs throughout the war, the almighty Yamato Class Battleships carried several of them.
Seagull,seamew, kingfisher and finally the seahawk show the evolution of spotter floatplanes
While we relied on
seafox,swordfish and the seagull/walrus
 

W21A

LE
Book Reviewer
I believe such Spotter Planes were used in the Pacific to direct Shore Bombardments from Warships and were at times used to rescue downed Aircrews.

As far as l know the Japanese (lacking American Radar Guided Fire Control) used theirs throughout the war, the almighty Yamato Class Battleships carried several of them.
IIRC Someone upstream pointed out (Or posted a link.) that IJN doctrine was that spotters flew from battleships and cruisers. Carrier aircraft were for strike and CAP only. Hence another reason for large amount of spotter floatplanes.

Edited.
 
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