# Royal navy A.A.gunnery.



## starling (Aug 14, 2012)

Hi all,of all the major belligerent ww2 Countries,did the royal Navy have the "worst"Anti Aircraft Gunnery.? Thankyou ,Starling.


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## kettbo (Aug 14, 2012)

Are you talking Gunnery as in shots fired to shots hit? gun direction? over-all capability? 

What period are you asking because overall things got better for them with more AAA weapons, DP mounts 5" and below, more RFC. 
Early war old school ideas and small fitment of AAA weapons. For example prewar DDs had a single AAA gun 4" and some auto cannon, late war classes had twin or single DP mounts (when available) with TDC and RFC and VT/Proximity fusing. Larger ships got better AAA suites during overhauls or repairs. Some of the early war commissioned capital ships had the 5.25" gun and later strong 40mm close-in AAA

Early on I'd have to say the RN was POOR, like most everybody else in late 1939/1940.

o The USN had the 5"/38 most in DP mounts initially and the 40mm coming into service in vast numbers '42/43. Pretty good equipment then add VT fusing and RFC, becomes very good compared to others. 
o IJN 127mm were DP in most of the newer classes, all the new build stuff and heavy units that were modernized. Decent weapon, useful ROF. Just lacking in RFC direction most of the war. Big shortfall was the 23mm AAA close in armament lacked the range and killing power needed
o The Germans had secondary weapons then heavy AAA which was old-school. Smaller warships slightly better than most others early war AAA outfit. The later 37s were capable, quad 20s were lethal if you took hits, twin 20s useful. Again, RFC and TDC not up to the USN in their 1944/45 standard.


Think quantity and quality. Anti Air defense thinking and weaponry was primitive at the beginning of the war. Little plane on ship action in the past for the threat analysts to develop defense concepts and weapons. Throughout the war, more weapons added, thus more rounds shot upward means more planes shot down or damaged, or distracted. Add central control, then improved control, then Radar Fire Control. VT fusing made "Close" count for those who had it.


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## starling (Aug 15, 2012)

Thanks for that fine eloquent answer,cheers.Starling.


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## starling (Aug 15, 2012)

Hey guys,Did any major R.N.units,BB's or C.V's recieve anti aircraft "refits",whilst in U.S.shipyards.?thanks,Starling.


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## starling (Aug 17, 2012)

Hey guys,so would you say that late war(let's say in the P.T.O),that the R.N.was on a par with U.S.Navy.? Obviously the guns themselves were different in the main D.P.weapons,but was the Radar,etc nearly equal.Thanks,Starling.


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## stona (Aug 17, 2012)

Royal Navy gunners typically overclaimed at a rate of 4 or 5 to 1, hardly surprising when every gun within a mile might be firing on the same target.

Shipboard anti aircraft defence is a last resort and the least effective of the so called "three layers".

The first defence is interdiction of enemy airfields or carriers to prevent their aircraft taking off to attack your ships or to destroy them before they can do so.

Second is fighter protection provided by a task forces air group to prevent aircraft getting within efective range of your naval assets.

Steve


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## RCAFson (Aug 21, 2012)

In 1939, the Royal Navy had the most advanced naval AA gunnery systems of any navy. Take a look at the design and AA weapons systems of HMS Renown and HMS Valiant in 1939 and compare them to any other foreign ship in 1939. 

Renown had 4 HACS Mk IV directors controlling 20 4.5in (10 x 2) DP guns and 24 (3 x 8 ) 40mm pom-poms each with it's own director and 16 .5in MGs (4 x 4). No other navy had any thing even close to this level of AA firepower backed up by full director control.

In 1940 the battleship K.G.V. introduced the Mk IVGB director, 4 of which controlled her 16 x 5.25in DP guns, plus she had 4 MK IV pom-pom directors controlling 32 40mm pom-pom guns and KGV also had type 279 radar which gave KGV radar ranging for aerial targets. Again this was far superior to anything else afloat, in terms of AA capability.

In 1941 the KGV class battleship, Prince of Wales, went into service with no less than 9 AA FC radars including 4 x type 285 which provided ranging for her 4 HACS Mk IVGB directors, which controlled the 5.25in guns, and 4 x type 282 radars which provided radar ranging for her 4 Mk IV pom-pom directors. PoW was so far ahead of the field in terms of AA control, that she simply had no rivals in any other navy - the Axis navies never developed AA FC radar. The USN did not begin to fit AA FC radars to their ships until early 1942, and they only managed that because of UK and RN technical assistance. 

I recently read a fascinating book called "Flagship to Murmansk" by Robert Hughes which gives a very vivid account of RN AA gunnery aboard the AA cruiser, HMS Scylla.


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## fastmongrel (Aug 22, 2012)

RCAFson said:


> the Axis navies never developed AA FC radar.



Not true the German Navy had AA FC radars and they were no better or worse than Allied equivalents just not fitted to enough ships.

German Radar of World War II


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## RCAFson (Aug 22, 2012)

fastmongrel said:


> Not true the German Navy had AA FC radars and they were no better or worse than Allied equivalents just not fitted to enough ships.
> 
> German Radar of World War II



The only mention, in the above article, of of AA FC radars actually fitted to a ship was this set, fitted to Tirpitz:


> *Again in the spring or summer of 1944, the third AA director, fitted just abaft the mainmast (German nickname 'Wackeltopf') was raised by 2m and equipped with an AA gunnery radar*, probably Würzburg-C or Würzburg-D. As previously mentioned the Würzburg had originally been developed for the Luftwaffe, but it was later navalised for the German Navy's AA shore batteries under the following designation: FMG 39T/C (later FuSE 62C) Würzburg-C became the Navy FuMO 212, and FMG 39T/D (later FuSE 62D) Würzburg-D became the Navy FuMO 213. This reveals a fact that has not previously been published.
> 
> Tirpitz had the most sophisticated radar equipment of all the larger German surface units. *However, without interviewing eye-witnesses we cannot know that these sets were not experimental, nor how effective they were under battle conditions.*



Tirpitz at that point was just a floating gun battery.


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## parsifal (Aug 22, 2012)

stona said:


> Royal Navy gunners typically overclaimed at a rate of 4 or 5 to 1, hardly surprising when every gun within a mile might be firing on the same target.
> 
> Shipboard anti aircraft defence is a last resort and the least effective of the so called "three layers".
> 
> ...



im afraid i dont agree with this. Westermann has done an exhaustive study on AA effectiveness, which shows that for high level strategic bombers , it was about as effective as your 'second tier' of defence (the land based equivalent at least). What you are saying is not without some basis....there was gross overclaimimg, but then so too was there overclaiming in the air as well.

The other thing is that AA effectiveness should not be measured on the kill rates achieved. Its primary mission was always to affect accuracy rather than kill things, and ther is strong evidence to support the notion that the RN was quite good at that.

The RN was unfortunate in that it did not have a great director control system until later in the war, and its failure to produce a widespread DP for DDs cost it dearly early on. this makes a bit of a nonsense the claim that "every gun within a mile of the target would open up at the atackers. Light AA was really only effective for the target ship and one ship adjacent, since the TDs were often at least 700 yds and effective range of weapons like the oerlikon about 400 yards, over open sights.

Ive read somewhere (will try and pinpoint the source), that in 1942 the average ammunition expenditure per kill was about 2500-3000 rounds for the RN. At the same time USN ammunition expenditure per kill was about 1500 rounds per kill. In late 1944 that same USN study estimated the average rounds per kill was down to 500 rpk.


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## fastmongrel (Aug 22, 2012)

parsifal said:


> Ive read somewhere (will try and pinpoint the source), that in 1942 the average ammunition expenditure per kill was about 2500-3000 rounds for the RN. At the same time USN ammunition expenditure per kill was about 1500 rounds per *kill*. In late 1944 that same USN study estimated the average rounds per kill was down to 500 rpk.



I think that should average rounds per *claim*. Kills is another matter some claims for certain ships are so extraordinary that it is laughable they must have shot down every single attacker if the claims were true. 

Your right that the main mission of AA is to keep the ship floating and fighting, knocking a plane down is a distant second if your sinking. it took the proximity fuse, gun stabilisation, stabilised radar and automatic fire control to start killing planes in big numbers, before 1944 it didnt matter how good your fire control was it still relied on humans making judgements which is always going to cause errors particulary if an action is a long one. It didnt matter if you had the USN Mk 37 director or the RN Mk IV the problem of hitting a moving plane from a moving ship with a fire control and gun system that was at best stabilised in 2 planes and initially aimed by the Mk1 eyeball was such that most fire was little more than undirected untimed barrage fire.

Before 1944 most Destroyers would have been better off landing there heavy DP guns and AA fire control and shipping lighter Low Angle main guns with as many gyro aimed automatic weapons as could be fitted and manned.


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## renrich (Aug 22, 2012)

Quite a number of years ago I read a book authored by a retired British Admiral about the RN during WW2. I am a great admirer of the RN. Read every one of C S Forester's books and one of my favorite books in my library is "Castles of Steel" by Massie. My favorite naval battle to read about is Jutland. In the WW2 book by the Brit Admiral, he said that the RN, on the whole, had very poor AA because of poor director performance.

Another subject I would like to put some perspective on is the armored flight decks of the RN CVs and the efficacy thereof. The RN lost four CVs in WW2, three by subs and one by surface action. The US lost four CVs in WW2, one by sub and three from bombs and torpedos. I have read thoroughly about the actions where the US CVs were lost and I question strongly that the CVs would have been sunk without the torpedo hits. I am not sure that it is therefore provable that the armored flight decks were necessary along with their drawbacks. The torpedos were the ship killers and the armor on flight decks could not protect from them as evidenced by Courageous, Eagle and Ark Royal.


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## Glider (Aug 22, 2012)

This is of course a complex subject but there can be little doubt that in many ways the RN were the most advanced AA at the start of the war. The converted Merchent AA vessels were as good as the best warships around, the old WW1 cruisers were often converted to AA vessels, some old WW1 destroyers were converted to escort vessels with a comprehensive AA complement. The first dedicated AA cruisers were being builts and early BB's were being equipped with a heavy AA defense. 

Few would deny that the serious mistake was not giving DD's a DP main weapon indeed 6 x 4in DP would have been better than the 4 x 4.7 LA normally carried. 

However the USN with the 5in DP and proximity fuse combined with the latest directors were by far the best. The RN had HMS Delhi equipped with this combination and wanted these fitted to all RN destroyers ( I think it was 60 sets) but the US couldn't supply these as the USN had priority.

For the last 12-18 months of the war with the quad 40mm the USN had the best AA outfit


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## kettbo (Aug 22, 2012)

from British vessels lost at sea in World War 2 - major warships

just the ones that sank, lots more damaged by aircraft

EDIT 23 AUG
Battleship (somehow I deleted this off the list)
*PRINCE OF WALES (35,000t, 31/3/41), sunk by Japanese torpedo-aircraft, E coast of Malaya, December 10, 1941 (Casualty List)*


Battlecruisers

*REPULSE (33,250, 1916), sunk by Japanese torpedo-aircraft, E coast of Malaya, December 10, 1941 (Casualty List)*

Monitor

*TERROR (7,200t, 1916), bombed (22nd) and sunk off Derna, Libya, February 23, 1941*

AIRCRAFT CARRIERS

Fleet carriers

*HERMES (10,850t, 1924), sunk by Japanese aircraft off Ceylon, April 9, 1942 (Casualty List)*



CRUISERS


*CALCUTTA (AA ship, 4,200t, 1919), sunk by aircraft bombs during evacuation of Crete, June 1, 1941 (Casualty List)*

*CORNWALL (10,000t, 1928), sunk by Japanese dive bombers, Indian Ocean, April 5, 1942 (Casualty List)*

*COVENTRY (AA ship, 4,290t, 1918), sunk by dive bombers, E Mediterranean, September 14, 1942 (Casualty List)*

*CURLEW (AA ship, 4,290t, 1917), sunk by aircraft bombs, off Ofotfiord, Norway, May 26, 1940 (Casualty List)

FIJI (8,000t, 17/5/40), sunk by aircraft bombs during evacuation of Crete, May 22, 1941 (Casualty List) Note, sunk by Bf109s and Ju88s

GLOUCESTER (9,600t, 31/1/39), sunk by aircraft bombs during evacuation of Crete, May 22, 1941 (Casualty List)

SOUTHAMPTON (9,100t, 1937), sunk by dive bombers, E of Malta, January 11, 1941 (Casualty List)


*** YORK (8,250, 1930), lost at Suda Bay, Crete after damage on various dates by explosive motor boats and aircraft, May 22, 1941


Cruiser minelayers

LATONA (2,650y, 4/5/41), attacked by aircraft, E Mediterranean, October 25, 1941 (Casualty List)


DESTROYERS

AFRIDI (Leader, 1,870t, 1938), sunk by aircraft bombs, off Norway, May 3, 1940

BASILISK (1,360t, 1931), sunk by aircraft bombs, off Dunkirk, France, June 1, 1940

BEDOUIN (1,870t, 15/3/39), sunk by aircraft torpedo, Central Mediterranean, June 15, 1942

BOADICEA (1,360t, 1931), sunk by aircraft torpedo off Portland, English Channel, June 13, 1944

BRAZEN (1,360t, 1931), sunk by aircraft off Dover, S England, July 20, 1940

CODRINGTON (Leader, 1,540t, 1930), bombed and sunk in Dover Harbour, S England, July 27, 1940

DAINTY (1,375t, 1932), sunk by aircraft, off Tobruk, Libya, February 24, 1941

DARING (1,375t, 1932), sunk by U-boat torpedo off Duncansby Head, N Scotland, February 18, 1940

DEFENDER (1,375t, 1932), sunk by aircraft bombs, off Sidi Barrani, Egypt, July 11, 1941

DELIGHT (1,375t, 1933), bombed and sunk off Portland, S England, July 29, 1940

DIAMOND (1,375t, 1932), sunk by aircraft bombs during evacuation of Greece, May 27, 1941

GRENADE (1,335t, 1936), sunk by aircraft bombs, in Dunkirk Harbour, France, May 29, 1940


GREYHOUND (1,335t, 1936), sunk by aircraft bombs during battle of Crete, May 22, 1941

GURKHA (1,870t, 1938), sunk by aircraft bombs, off Stavanger, Norway, April 9, 1940

HAVANT (1,400t, 1939), sunk by aircraft bombs, off Dunkirk, France, June 1, 1940


HEREWARD (1,340t, 1936), sunk by aircraft bombs, off Crete, May 29, 1941


IMPERIAL (1,370t, 1937), sunk by own forces after being bombed, off Crete, May 29, 1941 oops!

INGLEFIELD (Leader, 1,530t, 1937), sunk by aircraft, glider-bomb,off Anzio, W Italy, February 25, 1944

INTREPID (1,370t, 1937), sunk by aircraft, in Leros Harbour, Dodecanese, September 27, 1943

JACKAL (1,760t, 13/4/39), sunk by aircraft, E Mediterranean, May 12, 1942

JANUS (1,760t, 5/8/39), sunk by aircraft torpedo off Anzio, W Italy, January 23, 1944


JUNO (1,760t, 25/8/39), sunk by aircraft bombs during battle of Crete, May 21, 1941

KASHMIR (1,760t, 26/10/39), sunk by aircraft bombs during battle of Crete, May 23, 1941

KEITH (Leader, 1,400t, 1931), sunk by aircraft bombs, off Dunkirk, France, June 1, 1940

KELLY (Leader, 1,760t, 23/8/39), sunk by aircraft bombs during battle of Crete, May 23, 1941

KINGSTON (1,760t, 14/9/39), sunk by aircraft bombs, at Malta, April 11, 1942

KIPLING (1,760t, 22/12/39), sunk by aircraft, E Mediterranean, May 11, 1942

LANCE (1,920t, 13/5/41), sunk by aircraft bombs, at Malta Subsequently salved, April 9, 1942

LIVELY (1,920t, 20/7/41), sunk by aircraft, E Mediterranean, May 11, 1942


MASHONA (1,370t, 30/3/39), sunk by aircraft bombs, N Atlantic, May 28, 1941

NESTOR (On loan to RAN, 1,760t, 12/2/41), sunk by aircraft bombs, E Mediterranean, June 15, 1942

PANTHER (1,540t, 12/12/41), sunk by aircraft bombs, Scarpanto Strait, Dodecanese, October 9, 1943

QUENTIN (1,705t, 15/4/42), sunk by aircraft torpedo, W Mediterranean, December 2, 1942

TENEDOS (1,000t, 1919), sunk by aircraft during attack on Colombo, April 5, 1942

VALENTINE (Leader, 1,090t, 1917), bombed, grounded and abandoned in River Scheldt, Belgium, May 15, 1940

VAMPIRE (On loan to RAN, 1,090t, 1917), sunk by aircraft bombs, E of Ceylon, April 9, 1942


WATERHEN (On loan to RAN, 1,100t, 1918), sunk by aircraft bombs, off Sollum, Egypt, June 29, 1941

WESSEX (1,100t, 1918), sunk by aircraft bombs, off Calais, France, May 24, 1940

WHITLEY (1,100t, 1918), damaged by bombs, beached between Nieuport and Ostend, Belgium, May 19, 1940

WILD SWAN (1,120t, 19), sunk by aircraft bombs, Western Approaches, June 17, 1942

WREN (1,120t, 1923), bombed and sunk off Aldeburgh, Suffolk, E England, September 27, 1940

WRESTLER (1,100t, 1918), damaged beyond repair by mine off Normandy, June 6, 1944

WRYNECK (1,100t, 1918), sunk by aircraft bombs during evacuation of Greece, May 27, 1941

ZULU (1, 870t, 6/9/38), sunk by aircraft bombs, E Mediterranean, September 14, 1942

cut off lesser units for space consideration


Hipshot: Lack of AAA, AAA ammo, and gunnery control lead to massive losses through 1942
Losses in the Med were severe*


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## RCAFson (Aug 23, 2012)

kettbo said:


> from British vessels lost at sea in World War 2 - major warships
> 
> just the ones that sank, lots more damaged by aircraft
> 
> ...



Let's consider a few examples from May of 1941. Fiji and Gloucester were detached from the main fleet that was covering Crete, and in so doing were exposed to wave after wave of Nazi bombers, until both ships finally ran out of ammo, and the Luftwaffe was able to close in for the kill:


> 2. It was dawn on May 21st that HMS Fiji, in company with the majority of med. Fleet left Alexandria. For the last fortnight units of the fleet had patrolled the waters round Crete waiting for the German assault. Each night cruisers had been busy ferrying supplies of men and material to the island in a hurried preparation. At last news had come from reconnaissance aircraft that convoys were stealing down the Greek coast and we knew the attack was imminent.
> 
> 3. On arrival off Crete about 2100, the fleet split up into 5 separate units. Two striking forces of cruisers and destroyers entered the Aegean itself, one force patrolled the north eastern entrance to the Aegean; one patrolled the NW entrance, while the main battle fleet cruised to the south'ard as a covering force just in case the Italian fleet came on the scene. The Fiji, only 4 months in commission again after being repaired from a torpedo attack, was detailed to accompany the war hardened Gloucester, who had come successfully through all the actions in the med, the two being escorted by the destroyers Kandahar and Kingston. We were closed up at action stations all night but nothing happened and dawn saw all units withdrawing on to the main battle-fleet off the Western end of Crete. On board the Fiji we were just changing from action to A.A. Defence when R/Df reported "aircraft Green 100, large formation 15 miles". All that day formations attacked the fleet, but we kept together and put up a massed barrage that deterred them from pressing home their attacks. Some of the daring spirits however sometimes broke through and one registered a hit on Warspite which wiped out her starboard 4-in. Battery but did not decrease her speed.
> 
> ...



So Fiji was using radar directed AA to defeat the attacks, at a time when the USN didn't have any radar FC of any kind. Fiji and Gloucester were overwhelmed by massive numbers of aircraft, until they simply ran out of ammo...and that doesn't sound like ineffective AA to me.

Mashona and Tarter had 6 x 4.7in guns controlled by by a FC computer and HA Director and a twin 4in gun aft, she also had a 4 barrel pom-pom and either 20mm guns or additional quad .5in MGs. 

Mashona was in company with Tarter, and here's a summary of the action that led to her loss:


> After this, on 28 May Tartar was returning to Scapa Flow with HMS Mashona, when they came under heavy air attack west of Ireland, and Tartar's action report states: "...It is believed that all attacking aircraft were H.E. 111's. Occasionally a F.W. Condor was seen shadowing astern. *It is estimated that about 50 aircraft took part in the attacks over a period of 13 hours..."*[5] The Mashona was hit and badly damaged, eventually capsizing, but in return Tartar shot down an He 111 bomber.[6] Tartar was able to rescue 14 officers and 215 ratings, and transported them to Greenock. During this engagement " Tartar used her Fuze Keeping Clock to aim her 4.7" guns and "...Every gun was used, the 4.7" in controlled fire and the 4" and close range weapons firing independently. 290 rounds of 4.7", 255 rounds of 4", 1,000 rounds of pom pom and 750 rounds of .5 machine gun ammunition were fired."[7]
> HMS Tartar (F43) - Wikipedia, the free encyclopedia



So we have a series of lengthy attacks, that led to one of the two destroyers being hit; again this doesn't sound like ineffective AA. Rather, it seems that the Luftwaffe kept their distance, and relied upon shear weight of numbers to score hits against RN's ships that were dispersed and open to attack by overwhelming numbers of aircraft - I don't see any other navy doing better in the same time frame, and I'm actually pretty sure that they would do worse, since no other navy had as much AA firepower per ship or the same level of FC technology as the RN in May 1941.


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## fastmongrel (Aug 23, 2012)

Go ask any current Naval commander how he would like to operate in the Med within 30 miles of the airfields of 2 major powers. He would probably go a bit green round the gills and ask you to change the subject. There is a long line of critics of the Royal Navy (including myself with my 20/20 hindsight) but what other Navy could have operated in the Med and not lost a similar number of vessels.


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## Glider (Aug 23, 2012)

This might be of interest. Its a summary of a decoded Luftwaffe Enigma message Aug 1940


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## renrich (Aug 23, 2012)

I have a Janes, 1945 ( not an original) and a 1942 Janes(original) When you look at the war loss section, it is staggering how many British vessels went down. Probably the most dangerous British type to serve on in WW2 was the armed merchant cruiser. Very sad.


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## parsifal (Aug 23, 2012)

Here is a link to the Hyperwar site. Chapter 3 gives a pretty good summary of AA effectiveness and the amount of ammunition expended for each kill by the USN 

HyperWar: Antiaircraft Action Summary--World War II


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## parsifal (Aug 23, 2012)

Unfortunately I cant find much reliable estimates of RN ammunition expenditure for each kill. some sources suggest or estimate about 1000 rounds per kill, but that seems pretty optimistic. From the look of it, I think we are going to have to look at random or typical enagements to get a representative sample....where the ammunition expenditure is known, and the number of kills is also known. Anyone got any examples like that?


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## RCAFson (Aug 23, 2012)

parsifal said:


> Unfortunately I cant find much reliable estimates of RN ammunition expenditure for each kill. some sources suggest or estimate about 1000 rounds per kill, but that seems pretty optimistic. From the look of it, I think we are going to have to look at random or typical enagements to get a representative sample....where the ammunition expenditure is known, and the number of kills is also known. Anyone got any examples like that?



I gave a couple of examples earlier, but it becomes a pretty huge task. I looked through the USN AA summary linked earlier, and it is stating a lot more AA kills than I'm aware of. Since it was published in Oct 1945, it must have been based on wartime claims, not post war verified AA kills. 

Here's a summary of RN AA technology:
The Gunnery Pocket Book - Part 4


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## kettbo (Aug 23, 2012)

RCAFson said:


> In 1940 the battleship K.G.V. introduced the Mk IVGB director, 4 of which controlled her 16 x 5.25in DP guns, plus she had 4 MK IV pom-pom directors controlling 32 40mm pom-pom guns and KGV also had type 279 radar which gave KGV radar ranging for aerial targets. Again this was far superior to anything else afloat, in terms of AA capability.
> 
> In 1941 the KGV class battleship,* Prince of Wales*, went into service with no less than 9 AA FC radars including 4 x type 285 which provided ranging for her 4 HACS Mk IVGB directors, which controlled the 5.25in guns, and 4 x type 282 radars which provided radar ranging for her 4 Mk IV pom-pom directors. PoW was so *far ahead of the field in terms of AA control, that she simply had no rivals in any other navy *- the Axis navies never developed AA FC radar. The USN did not begin to fit AA FC radars to their ships until early 1942, and they only managed that because of UK and RN technical assistance.



to which I must reply

*PRINCE OF WALES (35,000t, 31/3/41), sunk by Japanese torpedo-aircraft, E coast of Malaya, December 10, 1941 (Casualty List)*

pretty decent write-up on WIKI 
Sinking of Prince of Wales and Repulse - Wikipedia, the free encyclopedia
o some of that high tech RN AAA gadgetry was not working
o twin engine attackers, arrived in different groups many minutes apart 1140-1241, not like the coordinated large LW attacks in the MED
o new build PoW was hit by a Torpedo from a Nell that damaged the portside outer prop shaft, caused bad flooding, loss of that shaft use, loss of other portside shaft, caused a large list, and put many of the 5.25 guns and pom poms out of action (cut power)
o three torpedo hits to the starboard side later
o at least one bomb hit, some near misses
o Japanese 8 torpedo hits of 49 launched 16%, of these 4 on the PoW, 4 on Repulse Type 91 Torpedo 450mm / 17 3/4 inch
o four planes lost; three during the attack, one lost during landing

nice AAA technology, did not work when it is needed
bad luck on that hit location indeed, put most of the AAA out of action. Pretty sure the Japanese would have sunk both the RN ships even if the portside torpedo hit had been less disastrous. The Japanese had another strike package nearly ready to launch had it been required


re Action in the MED post 15 and 16

no doubting the courage of the RN sailors expending all their AAA ammo... 
rank stupidity of their superiors for putting them in harm's way for so long
threat planners in the design phase failed to provide enough AAA ammo or replenishment between contacts (we plan for and execute this in the Army)

One could look at this and say the RN had plenty of AAA Targets, plenty of time to shoot at the LW, plenty of practice, FIJI's "good RFC" and other good equipment _on paper_, yet the LW pounded the RN and the Fiji and Gloucester were lost. Defeating the attacks does not mean losing your ships. If all that RFC was so good, then they would have not used all their ammo! Again, command failure for putting those sailors there and not providing more ammo, or resupply.

Don't get me wrong here, I'm not anti-RN one bit. I'm just against statements akin to "Hooray for my side we had this marvelous stuff" when the reality was, "Oh crap, their must be something wrong with our bloody AAA today." First on 21-23 May 41 then again Dec 41. So you can say the RN had the best AAA and control stuff but they still lost a lot of ships to aircraft. I'm having trouble seeing how effective this AAA really was, I am curious as to the Actual German losses. I know the AAA fire prevented training standard bombing and torpedo accuracy, but the fires was insufficient in quantity and ACCURACY to deter the Germans or the Japanese from continuing their attacks, or bare minimum greatly reducing the number of attacking planes. So if they come at you still in droves through your defenses, To me that means ineffective.

Could any navy then have done better? Good question. I do not think other navies would attempt this brash course of action. Assuming it was the USN there, they probably would have done at least as well simply because the 5"/38 is a pretty fair DP weapon, 4-5 per DD. USN decidedly a good close-in weapon and stingy outfitting or the types they were authorized. I'll have to look more at the French and Italian Navies, pretty sure they would have done worse. IJN had DP guns but not lavish arrangements. All lacking good FC and RFC for sure but as I mentioned above, I'm not convinced it (FC and RFC) was effective early war as demonstrated in May and Dec 41.


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## RCAFson (Aug 23, 2012)

kettbo said:


> nice AAA technology, did not work when it is needed



Mashona and Tarter were attacked over a 13 hr period, Fiji and Gloucester over many hours as well. It becomes apparent that the Luftwaffe kept their distance and/or flew erratic courses which minimized their own losses but also minimized the accuracy of their bombing. The RN dispersed it's forces because they had to, not from stupidity. 

Here's a first hand account of a USN destroyer trying to repell an air attack, over a year later:



> On the 24th of August, Task Force 16 was the northernmost of the three forces and in the vicinity of Stewart Island. At dawn, we launched a flight of SBDs to search the arc from north to west to pinpoint the Japanese Forces. The first search produced no contact, so a second search was launched. It made contact, as did long range search planes from Espiritu Santo. A full aircraft Attack Force was prepared and launched. As the Attack Force flew northwestward, it encountered a large group of Japanese planes coming towards us and a melee ensued. Of the ships surrounding the Big E, North Carolina, Portland and Atlanta were on the 1,500 yard circle with our seven DDs on the 3,000 yard circle. We all had plenty of warning and got to our GQ stations well before the battle worked our way. There had been some changes in the director crew: Chief Wilson and Moore had been transferred to “new construction,” Canaday was our GQ rangefinder operator, and Copeland and I handled the rangekeeper. Radar reports started when the enemy was still some 60 miles distant. Dogfights raged and we could hear the chatter between pilots over the Bridge circuits. Many enemy planes were reported shot down, but there were plenty of planes left when they streaked down out of the sun!
> Warren Armstrong, standing on the control officer’s platform with his head out of his hatch, tried to coach the Mk-33 around to the diving planes. Jaworski and Serwitz would slew the director frantically by eye with their handwheels until, with Canaday’s advice, they thought they were “on target,” then would drop down to try to catch the plunging planes in their optics. It was an impossible task! At the rangekeeper, Copeland and I watched Warren’s feet and lower torso expectantly as he squirmed about, hoping he’d get the director “locked on” to something so we could shoot. The attack was coming in from high over our section of the screen. The enemy planes were passing over our heads as they bore in on Enterprise. We’d whirl the director to try to get our sights on a Jap, but it takes a big arc of train to make even a small change near the zenith. They’d be over the top and out the other side before we could settle on them. Jaworski on the Pointer’s scope reported “On Target” a couple of times, but he couldn’t follow the fast motion as the attackers dove in. *We never got a shot off!*
> http://destroyerhistory.org/goldplater/index.asp?r=40130&pid=40136



The 5in/38 might be a good weapon, but it can't hit what it can't be aimed at!

Maury had a Mk33:


> The USN never considered the Mk 33 to be a satisfactory system, but wartime production problems, and the added weight and space requirements of the Mk 37 precluded phasing out the Mk 33: "Although superior to older equipment, the computing mechanisms within the range keeper (Mk10) were too slow, both in reaching initial solutions on first picking up a target and in accommodating frequent changes in solution caused by target maneuvers. The Mk 33 was thus distinctly inadequate, as indicated to some observers in simulated air attack exercises prior to hostilities. However, final recognition of the seriousness of the deficiency and initiation of replacement plans were delayed by the below decks space difficulty, mentioned in connection with the Mk28 replacement. Furthermore, priorities of replacements of older and less effective director systems in the crowded wartime production program were responsible for the fact the Mk 33's service was lengthened to the cessation of hostilities."[19]
> Ship gun fire-control system - Wikipedia, the free encyclopedia



Talk about the pot calling the kettle black...


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## kettbo (Aug 23, 2012)

RCAFson,

I was adding on to my earlier post as you penned your note above. 
"All lacking good FC and RFC for sure but as I mentioned above, I'm not convinced it (FC and RFC) was effective early war as demonstrated in May and Dec 41." I agree, we're not seeing good control for the USN in 42 by your anecdote above. I am wondering though what is better; nearly every USN DD with 4 or 5 5"/38s DPs with bad FC or even under local control shooting vs RN DD with one 4" AAA gun. 
Hmmm, USS Wainwright DD417 defending PQ-17 comes to mind
1938 build, 1940 commission, 4x 5"/38s 4x .50cal (get real!!!!!)(will look to see if it was refit before this event, think not)
see CONVOY by Kemp, p 70 and 71 or Wiki USS Wainwright (DD-419) - Wikipedia, the free encyclopedia
I cannot recall an instance of a single RN DD of that period being singled-out for their AAA activities


Even end of war, Improved Fire Control radars and directors, VT fusing, massive AAA batteries, the attackers still got through. Far fewer mind you.


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## Glider (Aug 23, 2012)

A couple of observations



kettbo said:


> to which I must reply
> 
> *PRINCE OF WALES (35,000t, 31/3/41), sunk by Japanese torpedo-aircraft, E coast of Malaya, December 10, 1941 (Casualty List)*
> 
> ...



The forces were out of balance. The POW was the only ship to have a modern AA suite and has been pointed out lost most of its effectiveness from the first torpedo hit. (As an aside this was taught to us in the RN as a classic example of poor damage control practice). The Repulse had not been enhanced to any significant degree. As pointed out there was no fighter cover and in theory this was almost a practice run the the Japanese forces. Prior to the development of the proximity fuse actually shooting down anything with Heavy AA was at best difficult if not close to impossible. The RN HAA plans were effective againt the level bombers and these were damaged sufficiently to stop them making a second pass. They were not shot down but they did retire from the battle. Its the light AA that tended to do the most damage. Problem here is that against torpedo bombers the torps are probably already on the way when the planes are in effective range.



> re Action in the MED post 15 and 16
> 
> no doubting the courage of the RN sailors expending all their AAA ammo...
> rank stupidity of their superiors for putting them in harm's way for so long
> threat planners in the design phase failed to provide enough AAA ammo or replenishment between contacts (we plan for and execute this in the Army)


All these points are true but its a little more difficult to rearm at sea with an air battle going on than in the army. 



> I know the AAA fire prevented training standard bombing and torpedo accuracy, but the fires was insufficient in quantity and ACCURACY to deter the Germans or the Japanese from continuing their attacks, or bare minimum greatly reducing the number of attacking planes. So if they come at you still in droves through your defenses, To me that means ineffective.


The prime objective of AA fire is to stop the enemy from doing much damage by reducing the accuracy of the attacks. A battle where no ships are hit and no aircraft are shot down is a big win for the defence. Determined atackers will always get some into an attacking position. 

Also the first posting asked if the RN had the worst AA defence, clearly they didn't, and in my view there were the best. Was it totally effective is a different question and my reply is no, but then again at the start of the war, no one, no one knew what was needed to make the defence totally effective. Its fair to say that the RN AA defences were effective and did a lot to limit losses but it wasn't totally effective. 



> Could any navy then have done better? Good question.



No is the simple reply.

edit - Ammunition. This varied of course but the normal figure iro destroyers for the RN at the out break of war was about 200-250 rounds per gun. For the Japanese and USN it was around 150 rounds per gun. These figures increased as the war developed


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## kettbo (Aug 23, 2012)

Glider,

Appreciate your comments. My initial response too said nobody was good early on and that things got better
Certainly the RN was not below the average in AAA capability


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## Glider (Aug 23, 2012)

The increase in AA defences during the war was considerable. 
The POW when sunk had 16 x 5.25 DP guns, 44 x 2pd (5 x 8, 1 x4) and about 12 x 20mm. 
Her sister ships at the end of the war had 16 x 5.25 DP, 88 x 2pd (8 x 8, 6 x 4), 8 x 40mm and up to 65 x 20mm. It wasn't just the number of guns. Each 2pd and 40mm mounting had its own RDF director

I should add that the US N Carolina BB when launched in mid 1940 had 16 x 1.1 (4 x 4) 12 HMG


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## RCAFson (Aug 23, 2012)

kettbo said:


> RCAFson,
> 
> I was adding on to my earlier post as you penned your note above.
> "All lacking good FC and RFC for sure but as I mentioned above, I'm not convinced it (FC and RFC) was effective early war as demonstrated in May and Dec 41." I agree, we're not seeing good control for the USN in 42 by your anecdote above. I am wondering though what is better; nearly every USN DD with 4 or 5 5"/38s DPs with bad FC or even under local control shooting vs RN DD with one 4" AAA gun.
> ...



The addition of the HA 4in guns was really more of a morale booster, and I'm fairly certain that they would have preferred to add another quad pom-pom, but not enough were available. The real aircraft killers were the CIWS; the quad pom-pom, 20mm Oerlikon or quad .5in. 

Friedman, US Destroyers-An Illustrated Design History, p203:_"In theory, the 5in gun could counter either horizontal or torpedo bombers; it could not fire nearly fast enough to present any threat to dive bombers,which, ironically, were probably the most lethal threat to fast maneuverable craft such as destroyers."_

HMS Ledbury claimed 4 kills during Pedestal and almost certainly got 3. You can read her action report on this website:
HMS Ledbury story, Pedestal Convoy August 1942 
also check out:
HMS Scylla Story, 1942 - 1943 
for a detailed description of RN AA FC in action


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## parsifal (Aug 23, 2012)

I dont know that LAA is more effective or important than a good HAA weapon. 

5"/38 could engage an enemy target fom a horizontal range of 16000 yds. Thats gives it a pretty good area defence capability. An attacking torpedo bomber approaching at 150 knots, will be enaged for 192 seconds on the way in....thats a long time to be shot at i can tell you. Moreover the lethal burst radius of the 5in was from memory (correct me if Im wrong) about 90 feet 

Pom Poms had a range of 4000 yds give or take. They were considered a good gun, for what they were. im not arguing that the Pom Pom was not effective, just that heavier guns had certain advantages. At 4000 yds that gave them 48 seconds to engage,, however if we assume a drop rqange of 1500 yards, that reduces the engagement time for the LAA to about 30 seconds. i dont know the lethal radius of the 2 pounder, but it cant have been much....say 20 feet.

Interestingly, the US did consider the POM for general use in the USN. "_Among the machine guns under consideration were the Army's 37-mm and the British Navy's 2-pounder, more commonly known as the "pompom." The decision soon narrowed to a choice between the Bofors and the British gun. The British were anxious to have their gun adopted, and the fact that British aid would be readily available in initiating manufacture was put forward as an argument in favor of its selection. The 2-pounder, moreover was giving a good account of itself on British ships. On the other hand, there was the distinct disadvantage that the gun was designed for cordite powder, and no manufacturing facilities for the production of this ammunition were available in the United States. Thorough study revealed that the gun could not be converted to take American powder. Another consideration was muzzle velocity: The pompom had a relatively low velocity, 2350 feet per second as compared with 2830 for the Bofors. The success of the pompom in action was more than offset by the proved qualities of the Bofors in the hands of a number of powers who were using it, and the Bureau decided to join that group. Shortly after the Bureau's selection of the Bofors, British naval officials also decided to adopt the gun_"


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## kettbo (Aug 23, 2012)

Following the Kamikaze experience, the USN took a new look at AAA. The USN decided to scrap the 20mm, the 40mm, and adopted the 3"/50 in single and twin mounts. The weapon had a power rammer, 20 rpm ROF per tube, 85* max elev, range at 45 deg was 14,500 yds, electric mount. The 3"/50 served through the Cold War. The idea was to get them before they got close-enough to get to you. The 3" has a useful size bursting charge. So it was now possible to get the dive bombers. Alas, jet aircraft and air-launched missiles caused yet another re-look not long after the weapon entered service. Then came the cruise missiles...


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## RCAFson (Aug 23, 2012)

parsifal said:


> I dont know that LAA is more effective or important than a good HAA weapon.
> 
> 5"/38 could engage an enemy target fom a horizontal range of 16000 yds. Thats gives it a pretty good area defence capability. An attacking torpedo bomber approaching at 150 knots, will be enaged for 192 seconds on the way in....thats a long time to be shot at i can tell you. Moreover the lethal burst radius of the 5in was from memory (correct me if Im wrong) about 90 feet
> 
> Pom Poms had a range of 4000 yds give or take. They were considered a good gun, for what they were. im not arguing that the Pom Pom was not effective, just that heavier guns had certain advantages. At 4000 yds that gave them 48 seconds to engage,, however if we assume a drop rqange of 1500 yards, that reduces the engagement time for the LAA to about 30 seconds. i dont know the lethal radius of the 2 pounder, but it cant have been much....say 20 feet.



The RN 4.7in twin had the same area defence capabilities as the USN 5in/38 and could engage a torpedo bomber just as effectively, but it could not engage directly attacking dive bombers. To destroy a dive bomber, the 4in or 5in gun would have to score a direct hit, because no fuze prediction was possible during the dive; in fact most heavy guns were fired with a fixed time setting known as barrage fire, where the shells would be fuzed for say 1.5 or 2 secs so that they would explode at a fixed range, to try and hit the aircraft before it released it's bomb. I would wager that a quad pom-pom, firing about 400-460 rpm would have a better chance of scoring a hit than even 4 x 5in guns at 60-80RPM. Obviously a single 4 or 5in hit would destroy any aircraft, but a single 40mm hit would have a fairly high kill probability as well. I found an interesting booklet entitled Tribal Class Destroyers, by Peter Hodges. It has a raft of info regarding RN AA FC as used on Tribal class DDs. It has this to say:



> FIRE CONTROL CHANGES
> The original model of R/F Director Mk II was fairly quickly replaced by
> sub·model known as the Mk II (W). The suffix Ietter indicated that it had
> windshield attached to the rotating structure and, when fitted, the earlier
> ...



It also has this neat diagram




:

And you can visualize how a torpedo bomber or other low level attack could be kept under constant fire even with 40deg elevation guns. 2ndly you can see how, even with 40 deg elevation, that aircraft attacking other ships could be kept under fire, by other than the target ship, even with 40 deg elevation.


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## Glider (Aug 24, 2012)

The choice between the 40mm Bofors and the 2pd is one example of the UK not getting its act together. The 2pd was in production for many years with the RN starting well before the war and the eight gunned version was by far the most effective AA mount anywhere prewar. The 40mm was a more modern weapon and had been chosen by the British Army just before the war and apart from the other advantages, was lighter a very important consideration in a destroyer.
Why the UK would have argued for the 2pd over the 40mm is beyond me.


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## parsifal (Aug 24, 2012)

I agree, but it at least shows that it was not the total dog it is often made out to be.


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## RCAFson (Aug 24, 2012)

Glider said:


> The choice between the 40mm Bofors and the 2pd is one example of the UK not getting its act together. The 2pd was in production for many years with the RN starting well before the war and the eight gunned version was by far the most effective AA mount anywhere prewar. The 40mm was a more modern weapon and had been chosen by the British Army just before the war and apart from the other advantages, was lighter a very important consideration in a destroyer.
> Why the UK would have argued for the 2pd over the 40mm is beyond me.



The quad 2pdr had an on-mount magazine capacity of 114 rounds/gun (456 rounds and 1130 rounds on the octuple) and could fire for about one minute at full rate without reloading. It had a smaller crew than a twin bofors and a much higher effective RoF. The total weight of the quad 2pdr includes the on mount ammo, where the twin bofors weights are just for the mount. The pom-pom was liquid cooled and could fire until ammo exhaustion where the initial bofors mounts were aircooled, and it took the US quite a while to engineer a liquid cooled mount; I expect that they could have mass produced the pom-pom much more quickly. The pom-pom had director control on cruisers and larger ships right from the start, where the bofors had to wait until mid 1942 for the USN to develop a director.


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## fastmongrel (Aug 24, 2012)

Glider said:


> The 40mm was a more modern weapon and had been chosen by the British Army *just before the war* and apart from the other advantages, was lighter a very important consideration in a destroyer.



I imagine it takes longer to introduce a weapon into naval service than it does land service though later experience showed just bolting the Army Bofors to the deck was a quick way of getting a good weapon to sea. Perhaps the RN thought better to stick with what we have rather than go for a new weapon that needs a new production line. The RN certainly knew the Pom Pom was near the end of its life and had been looking for a replacement for several years but there is a certain inertia in replacing obsolescent but still relatively new weapons, the Treasury probably asked why do you want a new automatic AA gun when we have just spent millions on the last one.


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## parsifal (Aug 24, 2012)

It was as much about ammunition supply as anything. The RN had huge stocks of 2pdr ammunition, and the set up to build the guns. It took a long time to get the Bofors into service, for both Navies.....1943 for the USN and 1944 for the RN.....and the RN was at war in 1939. it was very much a case of "making do"


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## Shortround6 (Aug 24, 2012)

the British made their first issue of water cooled guns in Nov 1942 to the HMS Whimbrel (commissioned on the 13 January 1943) It may have take quite a while to actually start replacing existing 2pdrs instead of just fitting to new construction. 

The blast radius of the 2pdr was zero as was the blast radius of the Bofors. They were contact fused only. Which explains the US and British interest in fast firing 3" guns at the end of the war. The 3" was the smallest that could be fitted with proximity fuses at the time. 

Both the US and the British were able to examine Dutch twin 40mm stabilized mountings in the summer of 1940. The Hazemeyer fire control system. In some cases Dutch ships had their 40mm guns/mountings removed for study and replaced by 2pdr mountings.


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## kettbo (Aug 25, 2012)

Shortround6 said:


> the British made their first issue of water cooled guns in Nov 1942 to the HMS Whimbrel (commissioned on the 13 January 1943) It may have take quite a while to actually start replacing existing 2pdrs instead of just fitting to new construction.
> 
> *The blast radius of the 2pdr was zero as was the blast radius of the Bofors. *They were contact fused only. Which explains the US and British interest in fast firing 3" guns at the end of the war. The 3" was the smallest that could be fitted with proximity fuses at the time.
> 
> ...




errrrr, you may want to rephrase this.
Technically speaking, If it explodes, it has a blast radius. Maybe not where you want it


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## Shortround6 (Aug 25, 2012)

It was an answer to a previous post which stated :

" Moreover the lethal burst radius of the 5in was from memory (correct me if Im wrong) about 90 feet"

While any shell that explodes has a bust radius it only really matters in AA use if you can get the shell to explode near an aircraft. to do that you need either a proximity fuse or a time fuse. Aside from the self destruct feature, none of 40mm and under AA rounds had either so they had zero "lethal burst radius" or miss distance.


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## parsifal (Aug 25, 2012)

> While any shell that explodes has a bust radius it only really matters in AA use if you can get the shell to explode near an aircraft. to do that you need either a proximity fuse or a time fuse. Aside from the self destruct feature, none of 40mm and under AA rounds had either so they had zero "lethal burst radius" or miss distance


.

yes thats correct.....though VT fuses were eventually produced for the L70, that didnt happen until many years after the war. I dont think a time fuse was ever built. 
The only fusing was contact type


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## starling (Aug 25, 2012)

Hey guys,a quite fascinating thread.Starling.


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## Juha (Aug 25, 2012)

Hello
on the sinking of HMS Mashona on 28 May 41. It was sunk by I./KG 77, so by Ju 88s, normally a full Gruppe attacking formation consistedof 27 bombers.

Juha


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## Juha (Aug 25, 2012)

On 2pdr vs 40mm Bofors
From Britain 2-pdr [4 cm/39 (1.575")] Mark VIII
“_As originally introduced, this was a recoil operated, "controlled" (partially-automatic) weapon which used a manually turned crank to operate the firing gear in the quadruple and octuple mountings (see note below for a further explanation). In 1939 the octuple mountings design was changed to allow fully automatic firing but this was not extended to the quadruple mountings which were only produced in controlled versions throughout the war. However, the quadruple mountings did replace the crank-turning crewmember with an electric motor sometime during the war. 
A higher velocity projectile was introduced in 1938 and this required a different breech mechanism and other changes to the firing gear. However, guns firing only the older low-velocity projectiles were still manufactured throughout World War II. High velocity and low velocity ammunition was not interchangeable. There were also several other gun variations, as shown in the data tables below. It should be noted that standardization was never a high priority in British ordnance thinking prior to the 1950s. 
The internal gun mechanisms were very complex and required much care and skilled maintenance to keep them in working condition. Jams and stoppages were frequent, although the linked ammunition proved to be more reliable in service than the older belt-fed guns._”

And from Sweden, Britain, USA, Germany and Japan Bofors 40 mm/56 (1.57") Model 1936
"_The British considered the Bofors to be at least twice as effective as their own 2-pdr against torpedo bombers, but not much better than that weapon against kamikazes."_

And the RoFs, water cooled Bofors 120rpm, automatic 2pdr 115rpg and "controlled", that means quad, 2pdr 96-98 rpm

Juha

BTW the Finnish Navy got its first water-cooled 40mm Bofors guns during winter 40-41, they had been ordered in 1938, they replaced the older 2pdr guns on our coastal battleships (3900t, 4x10" + 8x4.1" + 4x2pdr/later4x40mm Bofors + 4 - 8x20mm Madsen)


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## parsifal (Aug 25, 2012)

Finns reckoned they shot down 128 russian a/c using their copies of the bofors. they claim that this equated to 392 rpk....pretty good shooting if correct. USN a the end of the war reckoned average 40mm expenditre was 550-600 rpk. i saw the other night one site claim the 2pdrs expended 2300 rpk....of course no referenced material to verify.


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## RCAFson (Aug 25, 2012)

Juha said:


> On 2pdr vs 40mm Bofors
> From Britain 2-pdr [4 cm/39 (1.575")] Mark VIII
> “



Navweaps has the MV wrong, they state LV/HV =1920/2300fps but the new gun MV = 2040/2400fps.


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## fastmongrel (Aug 26, 2012)

RCAFson said:


> Navweaps has the MV wrong, they state LV/HV =1920/2300fps but the new gun MV = 2040/2400fps.



The RN usually quoted velocity after a certain percentage of the barrel life had been used which varied from gun type to gun type.


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## Glider (Aug 28, 2012)

Shortround6 said:


> Both the US and the British were able to examine Dutch twin 40mm stabilized mountings in the summer of 1940. The Hazemeyer fire control system. In some cases Dutch ships had their 40mm guns/mountings removed for study and replaced by 2pdr mountings.



The Hazemeyer mounting with twin 40mm was produced for RN destroyers in the late war replacing the quad 2pd. It also had its own radar rangefinder and analogue computer. It was very accurate and guess what very unreliable an idea ahead of its time


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## parsifal (Aug 28, 2012)

what were its reliability problems?


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## fastmongrel (Aug 28, 2012)

parsifal said:


> what were its reliability problems?



From Navalweapons site Sweden, Britain, USA, Germany and Japan Bofors 40 mm/56 (1.57") Model 1936

The Mark IV twin mounting was derived from the Hazemeyer triaxial mounting which had its origins in the 1940 arrival in Britain of the Dutch minelayer Willem van der Zaan. The Mark IV was a self-contained twin mounting that had its own rangefinder, radar and analog computer on the mount. This mounting used Mark IV water-cooled guns and utilized a track and pinion system for elevating and training, powered via a Ward-Leonard system for automatic target tracking. The Mark IV was probably too advanced for its day and proved to be somewhat delicate for use on destroyers and sloops. The later STAAG and Buster designs were more robust, but very much heavier. According to service notes, the Mark IV was apparently used more often in manual mode than in power mode. Elevation was -10 to +90 degrees with cross-level of +/- 14 degrees with control cutting out at +/- 12 degrees. Maximum elevating speed was 25 degrees per second with the manually controlled joystick, but training and elevation control via automatic control was limited to little more than 10 degrees per second. Weight was 7.05 tons (7.16 mt). The later Mark IV* mounting differed in details of the controls and gyros. The following description taken from "Destroyer Weapons of World War 2" is of interest:

'The 7-ton "Haslemere," as it was generally known, was a brilliant concept, but unfortunately it needed more advanced technology than then existed. It cannot claim to have been the most popular of weapons but at least it provided a little light relief on occasions. When stationary in the "power-off" mode during maintenance, a combination of training, depression and cross-roll made it look for all the world as though it was about to fall off its gundeck. Observations like "I see the Haslemere is ill again" were common.'


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## Shortround6 (Aug 28, 2012)

All true but it does show that the RN was looking at other options besides the 2pdr, the trouble is finding the fine line between what is possible in the lab/on the test range and what is possible/reliable in the Norwegian/Barents sea or South Pacific weeks if not months out of dockyard is a hard thing to find.


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## Glider (Aug 28, 2012)

I cannot find the quote now but vibration from the gun was a problem. The guns, radar, rangefinder and computer were all on the same mounting and the vibration of the gun firing could cause problems. Generally speaking and there are a number of grey areas here, the UK had more sophisticated mountings for their 20mm and 40mm guns. Their ships were a lot smaller than USN destroyers, deck space was less and they had to make the most of what space there was


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## parsifal (Aug 28, 2012)

I always believed Hazemeyer and other triaxial mounts were a big step forward. That and the US type directors. Now Im not as sure.....any comments?


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## Glider (Aug 29, 2012)

I odn't doubt for a moment that they were a significant step forward but the Hazemeyer by trying to do everything on one mount was a step to far for the technology of the time. As I said it was an improvement on the quad 2 pd and some of the crews loved it but it took a lot of TLC to keep going. After all the RN could easily have switched back to the 2pd.


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## RCAFson (Sep 10, 2012)

Here's an interesting excerpt, showing that RN AA could be very effective, under the right circumstances:



> Saturday 20th September, Two bombing attacks took place on the Convoy. During the first attack bombs were dropped over the convoy at some distance from "Parramatta" and one merchant ship was hit and damaged, although she subsequently reached Aden afloat with assistance from various ships. The Escort engaged the planes without visible results. The second attack took place during the first dog watch. The five Italian planes, inexplicably gave H.M.S. "Auckland" and myself considerable warning by dropping several bombs some miles away before attacking. The remainder of the bombs (about 30) were aimed with obvious intention of attacking the Convoy, but they released early, and the entire outfit fell around "Parramatta". The ship, then nearly stopped getting in the mine-sweeps, was not struck, although there were several near misses. Although splinters flew over us there there were no casualties, and the minesweeping party aft calmly continued to get in the sweeps with the after gun firing over their heads and bombs dropping close around them. The Italian planes continued over the Convoy at approximately 14,000 ft and gave H.M.S "Auckland" and myself an unrivalled opportunity for steady firing for some minutes. Two of the aircraft appeared to drop out of formation, one going into a spin. It has been subsequently ascertained that not one of the five aircraft reached home, in fact we had a one hundred per cent success.[10]
> Fuze Keeping Clock - Wikipedia, the free encyclopedia



10)http://www.awm.gov.au/collection/records/awm78/290/awm78-290-1.pdf


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## Juha (Sep 10, 2012)

Hello RCAFson
In reality only one S 79 was slightly damaged by AA. Italians on their part claimed hits on two ships. Typical cases of optimistic reporting. Usually combat reports are reliable on own losses but optimistic on losses inflicted to enemy forces.

Juha


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## RCAFson (Sep 10, 2012)

Juha said:


> Hello RCAFson
> In reality only one S 79 was slightly damaged by AA. Italians on their part claimed hits on two ships. Typical cases of optimistic reporting. Usually combat reports are reliable on own losses but optimistic on losses inflicted to enemy forces.
> 
> Juha



OK thanks. Where did you read that?


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## Juha (Sep 10, 2012)

RCAFson said:


> OK thanks. Where did you read that?



From Chris Shores' Dust Clouds in The Middle East p. 61.

Juha


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## RCAFson (Sep 10, 2012)

Does Shores mention both attacks that day?


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## Juha (Sep 11, 2012)

Hello RCAFson
Shores only writes:"...S79s again attacked the Red Sea convoy, claiming hits on two ships..."(they had attacked the same convoy on 19 June) but it is difficult to believe that he has missed a loss of 5 S79s, after all there were only 12 S79s in the bombing units operating in Italian East Africa in June 40 (+ 4 in reserve) and 27 on 1 Jan 41. And usually he mentioned even light damages suffered, after all fighting in East Africa was a shoestring war. 

Juha


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## starling (Oct 17, 2012)

Thankyou ,starling.


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