Destroyers.....

[parsifal]

IIRC, the BPF suffered one of it's worst days for kamikaze hits on the CVs, when Vian took the 2 KGV class BBs along with several cruisers and destroyers away from the carrier escort, for a bombardment mission. In any event, the number of kamikaze attacks on the BPF is really insufficient to draw any conclusions. IMHO, we really have to compare the USN destroyers performance in 42/43 with the RN from 1939-43 if we want to draw any valid comparisons.

Incorrect

The attacks on the carriers are described in some detail in various sources, notably David Browns book "Kamikaze"


The BPF came in for repeated and sustained attacks from the Japanese from March through to the very end. This arose partly from the dispositions of the BPF.....it was placed in a critical sector of the campaign. There were over 1200 Kamikaze sorties flown against the BPF. The attacks against the carriers occurred over a 2 month period, with a summary I found as follws

"HMS Formidable
1) 4 May 1945: Struck by a Zero carrying one 250 kg bomb which caused a 2 foot square hole and a 24 x 20 foot depression in the armored flight deck. Some structural damage was inflicted and three fragments penetrated the hanger deck with one going through a center boiler and into the double bottom. Speed was reduced to 18 knots and she was out of action for five hours. This attack killed eight men, wounded 51 and destroyed eleven aircraft.*
2) 9 May 1945: Kamikaze strike into the after deck park killed one and wounded eight. Deck depressed 4.5 inches with a supporting beam distorted by 3 inches. Six Corsairs and one Avenger were destroyed on deck, and a blown out rivet allowed burning fuel to penetrate into the hanger, which together with the sprinkler system damaged a further eight Corsairs and three Avengers. Out of action for 25 minutes.*

HMS Illustrious
6 April 1945: A Judy (D4Y3) kamikaze struck a glancing blow to the island with the only apparent damage being a hole in the Type 272 radome forward of the bridge. However, after the plane skidded into the sea, its bomb exploded underwater close alongside. This inflicted severe structural damage, with the outer hull opened up and some of the frames cracked. The damage did not interrupt flight operations, but speed was limited to 19 knots. Sent home and arrived at Rosyth on 27 June 1945 for what was intended to be a four month repair and refit, but the end of the war slowed work and changed plans. She recommissioned in June 1946 as a trials and training carrier, replacing HMS Pretoria Castle.

HMS Indefatigable
1 April 1945: Struck by a Zero carrying one 250 kg bomb on the starboard side of island at the junction with the flight deck. Deck indented over 15 square feet by up to 3 inches but not penetrated. Much superficial damage inflicted by splinters and an intense fire started, but the fire was quickly brought under control and extinquished. Eight killed and sixteen wounded. Able to land Seafires about forty minutes after attack.* Repaired between 2 April and 1 May.

HMS Indomitable
4 May 1945: A Zero Kamikaze belly-landed next to the island but broke up and went over the side. Destroyed the radar arrays of the port midships directors but inflicted no serious damage to the ship. A bomb attached to the kamikaze exploded after the plane went into the water but this also inflicted no damage."

These were not the only attacks, but they are the successful attacks made against the carriers

So it is simply untrue to attribute the hits sustained to the alleged diversion of British escorts away from the battle line 9I havent checked this recently, but if my memory serves me, those detachments were made only after their positions in the AA defence rings were filled by other ships).


Here we have an actual campaign, in which the operational results are fairly well known. Why on earth do we need to compare less well documented campaigns, in vastly different operational conditions? It makes no sense to do that.

 

[Juha]

And to do that the Bensons had to give up a set of TTs. However, as designed, it seems pretty obvious that the JKN CIWS of a quad pom-pom and two quad .5in was vastly superior to 4 x .5in on the Bensons.

The late war armament on an N class destroyer was 6 x 4.7in, 1 quad pom-pom, 2 twin power 20mm, 2 x single 20mm, 2 x quintuple TTs. Also, the the RN opinion of the value of a quad pom-pom varied as to the target type; against a kamikaze they felt it was almost as good per barrel as a Bofors. It seems obvious that by surrendering a set of TTs that the N class could have exceeded the Bensons in late war CIWS.

Hello RCAFSon, Thanks for the answer!
But situation wasn't that simple, Napier lost its after TTs by 23 Jun 45 and got 3 single Bofors Mk IIIs instead, it also lost 2xsingle 20mm, Nepal also lost its after TTs by Jun 45, but got only one Bofors Mk III instead. Same to Nizam. Norman kept its after TTs and didn't got Bofors. Those were only RN's Ns left at that time. That according to Appendix 3 on Langtree's The Kelly's (2002), but in the caption on p. 185 he writes that "...the number of Bofors carried by the ships of the BPF is an unclear question and Nepal and Nizam carried at least one and possibly up to three whilst Napier seems to have carried 3 or possibly 4... Installing Bofors meant the removal of the aft tubes again."

Juha

 

[vinnye]

Found this on Wiki about the BPF, an exaggeration, but apt.
In March 1945, while supporting the invasion of Okinawa, the BPF had sole responsibility for operations in the Sakishima Islands. Its role was to suppress Japanese air activity, using gunfire and air attack, at potential Kamikaze staging airfields that would otherwise be a threat to U.S. Navy vessels operating at Okinawa. The carriers were subject to heavy and repeated kamikaze attacks, but because of their armoured flight decks, the British aircraft carriers proved highly resistant, and returned to action relatively quickly. The USN liaison officer on the Indefatigable commented: "When a kamikaze hits a U.S. carrier it means 6 months of repair at Pearl [Harbor]. When a kamikaze hits a Limey carrier it's just a case of 'Sweepers, man your brooms.'

 

[RCAFson]

Maybe you should try to get access to Edgar J. March's British Destroyers A History of Development 1892 - 1953 (1966) you would find out that A.C.N.S.(H) wrote in Sept. 40 "...4.7-in....40deg is good L.A., very bad H.A." Or that V.C.N.S. proposed 70deg or 80deg or more, that 55deg be pressed for Emergency Flotillas, if possible 60deg, "and ask U.S.A. if they can supply their new 5-in. guns and mountings, if not make details known to us"

Juha

This is a full verbatim quote for page 402:

402

BRITISH DESTROYERS

A.C.N.S, (H) affirmed that the primary function of a destroyer necessitated 4.7-in. armament, "but she must be capable of defending herself agamst high level bombing, dive bombing and torpedo bombers. At least 80 elevation required to engage effectively dive bombers, 4.7-in. 80° is a bad L;A. mounting, 55deg is inadequate against dive bombers and a poor L.A. weapon, 40° is good L.A., very bad H.A."
One 4-in. H.A. was adequate for high level bombing, "but dive bombers require wide dispersion of fire, 4 barrel pompom does not meet requirements, but not less than four, preferably six, Oerlikons will. I advocate 4.7-in, 40°, one 4-in. H.A., 4 to 6 Oerlikons."

Vice-Chief of Naval Staff could not agree with his Assistant Chief that L.A. efficiency should override the requirement that the main armament should be able to tire in the air. "At the start of the Spanish Civil War a big demand from sea and certain quarters within the Adrniralty that guns should be able to **** up to more than 40°. Demand resisted on plea would interfere with L.A. efficiency, the point was conceded m complicated mountings in 'L' and one later class. In my view this decision to continue 40° was fundamentally wrong. This war has shown quite clearly- that for one day on which a destroyer is likely to engage her opposite number, fifty on which she wants to engage aircraft. Opposite numbers likely to be engaged have dual purpose HA/LA, modern German 5in. to between 80° and 90° . . . 40° plus good A.A. is completely out of date." V.C.N.S. accepted that "at the moment when we have to turn out some sort of destroyer as quickly as we can we are forced to accept something less than the best". He proposed 70° or 80° or more, that 55° be pressed for Emergency Flotillas, if possible 60°, "and ask USA. if they can supply their new 5-in. guns and mountings, if not make details known to us".
Controller ruled 55 ° mountings, "every effort to produce without delay . . . presumably separate ammunition will load at high angles". A.C.N.S. declared: "If others can do it, we can also, HA/LA dual is ideal."

The D.N.O. was instructed to press on with the design of the 55° mounting, he thought it was possible that a twin Bofors with self-contained Hazemeyer control gear might be in production by the time the 5th and 6th E.F.s completed.

The ACNS was not stating that the 40deg 4.7in twin was a bad mounting, only that 40deg was insufficient to engage dive bombers. However on page 396 the value of 4in guns against divebombers was compared:

A signal was sent to the C.s-in-C. "Theoretical investigation shows that the lethal value of a single F.K.C. controlled 4-in. gun in a destroyer against dive bombers is less that that of an Oerlikon up to 3000 ft. and considerably less than that of a 4-barrelled pompom up to 10,000 ft. Therefore propose to replace 4-in. H.A. in 'J' class and later and the 3-in. in 'E' to 'I' by the second set of T.T.s as opportunity occurs or by additional Oerlikons."

So the value of a DP 4in gun was less than one 20mm gun and much less than a quad pom-pom - so a 40deg armed ship with a heavy CIWS would be more effective against DBs than one which sacrifised the CIWS for a HA main armament.

Note also the RN tendency to credit their enemy opposite numbers with better weapons and technology than they actually had. No German destroyer was armed with HA FC and a DP gun in WW2, AFAIK, although some of the smaller DEs might have had 4.1 DP guns.

 

[RCAFson]

Incorrect

The attacks on the carriers are described in some detail in various sources, notably David Browns book "Kamikaze"


The BPF came in for repeated and sustained attacks from the Japanese from March through to the very end. This arose partly from the dispositions of the BPF.....it was placed in a critical sector of the campaign. There were over 1200 Kamikaze sorties flown against the BPF. The attacks against the carriers occurred over a 2 month period, with a summary I found as follws

"HMS Formidable
1) 4 May 1945: Struck by a Zero carrying one 250 kg bomb which caused a 2 foot square hole and a 24 x 20 foot depression in the armored flight deck. Some structural damage was inflicted and three fragments penetrated the hanger deck with one going through a center boiler and into the double bottom. Speed was reduced to 18 knots and she was out of action for five hours. This attack killed eight men, wounded 51 and destroyed eleven aircraft.*
2) 9 May 1945: Kamikaze strike into the after deck park killed one and wounded eight. Deck depressed 4.5 inches with a supporting beam distorted by 3 inches. Six Corsairs and one Avenger were destroyed on deck, and a blown out rivet allowed burning fuel to penetrate into the hanger, which together with the sprinkler system damaged a further eight Corsairs and three Avengers. Out of action for 25 minutes.*

HMS Illustrious
6 April 1945: A Judy (D4Y3) kamikaze struck a glancing blow to the island with the only apparent damage being a hole in the Type 272 radome forward of the bridge. However, after the plane skidded into the sea, its bomb exploded underwater close alongside. This inflicted severe structural damage, with the outer hull opened up and some of the frames cracked. The damage did not interrupt flight operations, but speed was limited to 19 knots. Sent home and arrived at Rosyth on 27 June 1945 for what was intended to be a four month repair and refit, but the end of the war slowed work and changed plans. She recommissioned in June 1946 as a trials and training carrier, replacing HMS Pretoria Castle.

HMS Indefatigable
1 April 1945: Struck by a Zero carrying one 250 kg bomb on the starboard side of island at the junction with the flight deck. Deck indented over 15 square feet by up to 3 inches but not penetrated. Much superficial damage inflicted by splinters and an intense fire started, but the fire was quickly brought under control and extinquished. Eight killed and sixteen wounded. Able to land Seafires about forty minutes after attack.* Repaired between 2 April and 1 May.

HMS Indomitable
4 May 1945: A Zero Kamikaze belly-landed next to the island but broke up and went over the side. Destroyed the radar arrays of the port midships directors but inflicted no serious damage to the ship. A bomb attached to the kamikaze exploded after the plane went into the water but this also inflicted no damage."

These were not the only attacks, but they are the successful attacks made against the carriers

So it is simply untrue to attribute the hits sustained to the alleged diversion of British escorts away from the battle line 9I havent checked this recently, but if my memory serves me, those detachments were made only after their positions in the AA defence rings were filled by other ships).


Here we have an actual campaign, in which the operational results are fairly well known. Why on earth do we need to compare less well documented campaigns, in vastly different operational conditions? It makes no sense to do that.

Vian took KGV and Howe on the bombardment mission on May 4th 1945:

At 1000 hours in position 23-54N, 125-10E the bombarding force comprising KING GEORGE V, HOWE, SWIFTSURE, GAMBIA and UGANDA escorted by destroyers GRENVILLE (D5), UNDINE, URCHIN, URANIA, UNDAUNTED and URSA, and EURYALUS and BLACK PRINCE, detached from the carrier force and closed Miyako at 24 knots. The carriers provided an additional CAP for this force as well as aircraft for spotting.
HMS King George V, British battleship, WW2

and your post shows that two carriers were hit that day, when deprived of the battleships' AA support along with their cruiser and destroyer escort. KGV and Howe were, by far, the most heavily AA armed carrier escorts, and no possible combination of cruisers and destroyers could adequately take their place.

 

[RCAFson]

Here we have an actual campaign, in which the operational results are fairly well known. Why on earth do we need to compare less well documented campaigns, in vastly different operational conditions? It makes no sense to do that.

Because the overall number of kamikazes that attacked the BPF are too small to be statistically valid, but we have large numbers of attacks against the RN from 1939-42 that can be compared to attacks against the USN in 1942 and we have good summaries and analysis of these action as well.

 

[Njaco]

can we keep things to one post.....

 

[Juha]

This is a full verbatim quote for page 402:


The ACNS was not stating that the 40deg 4.7in twin was a bad mounting, only that 40deg was insufficient to engage dive bombers. However on page 396 the value of 4in guns against divebombers was compared:


So the value of a DP 4in gun was less than one 20mm gun and much less than a quad pom-pom - so a 40deg armed ship with a heavy CIWS would be more effective against DBs than one which sacrifised the CIWS for a HA main armament.

Note also the RN tendency to credit their enemy opposite numbers with better weapons and technology than they actually had. No German destroyer was armed with HA FC and a DP gun in WW2, AFAIK, although some of the smaller DEs might have had 4.1 DP guns.

My interpretion is that ACNS also thought that 4.7-in 40 deg was also inadequate against high level bombing.

Again my interpretion is that he thought that good CIWS is better than single HA gun. I was suprised ACNS's 4.7-in, 40°, one 4-in. H.A., 4 to 6 Oerlikons oppinion because already for Nelsons RN wanted that at least 4 HA guns should be able to engage any aerial targets and was disappointed when in Nelsons max 3 HA guns could engage an aerial target. Also in army/AF HAA batteries had minimum 4 HAA guns, that was considered minimum for effective controlled fire.

Juha

 

[parsifal]

You just cannot draw the conclusions that you are inferring. There were also successful attacks on the carriers (that we know of) on the 1 April, 6 April and the 9 May.

Contrary to the popular belief, it was the CLAAs that were the most useful AA platforms rather than the BBs. The BBs needed far too big a TD to provide effective direct close support at a density. they were effective, and indeed essential for the british given the relative inneffectiveness of their DDs as AA platforms in the area defence role. They had had 6 years to correct that incidentally, and yet, according to the admirals that commanded them, were still inneffective at the role of protecting other ships, and indeed, too lightly armed with CIWs of indifferent quality to be considered effective. Only by adopting the most rigid of dispositions were they able to (partially) overcome these inherent design weaknesses.

The 4.5" guns went a long way to addressing at least some of these shortcomings. The other major advance in addressing the shortcomings of British fleet defence against a/c was the introduction of the 40mm Bofors. The same applies to the USN, but the USN had the advantage of already having an effective director control system in the Mk 37 and the 5/38, as well as having the pricless advantage of having a more widespread usage of VT fusing (about twice as much availability per ship)

 

[RCAFson]

You just cannot draw the conclusions that you are inferring. There were also successful attacks on the carriers (that we know of) on the 1 April, 6 April and the 9 May.

Contrary to the popular belief, it was the CLAAs that were the most useful AA platforms rather than the BBs. The BBs needed far too big a TD to provide effective direct close support at a density. they were effective, and indeed essential for the british given the relative inneffectiveness of their DDs as AA platforms in the area defence role. They had had 6 years to correct that incidentally, and yet, according to the admirals that commanded them, were still inneffective at the role of protecting other ships, and indeed, too lightly armed with CIWs of indifferent quality to be considered effective. Only by adopting the most rigid of dispositions were they able to (partially) overcome these inherent design weaknesses.

The 4.5" guns went a long way to addressing at least some of these shortcomings. The other major advance in addressing the shortcomings of British fleet defence against a/c was the introduction of the 40mm Bofors. The same applies to the USN, but the USN had the advantage of already having an effective director control system in the Mk 37 and the 5/38, as well as having the pricless advantage of having a more widespread usage of VT fusing (about twice as much availability per ship)

Two of the 4 kamikaze strikes that you detailed, occurred when the AA escort was weakened considerably.

Please provide some hard evidence for your statements of RN DD ineffectiveness. The problem with small scale attacks, is that the aircraft are free to radically manoeuvre, so that no system of AA FC in existence in WW2, could hit them, except by chance and/or sheer volume of fire so this tells us nothing.

 

[RCAFson]

This was the official USN tally of AA kills as of the end of 1942:

From the above:

USN AA kill claims / Lundstrom verified AA kills at:

Bougainville 6 / 1 ( 2 shared AA/fighter kills)

Coral Sea = 49 / 9 (5 to Crace's RAN and USN TG, 1 to Neosho and Sims rest to carrier TG)

Midway = 20 / 3 (1 = two shared AA and fighter kills)

Solomons
Aug 7-8 = 59 / 15 (2 on Aug 7, 13 on Aug 8 mostly CIWS)

Eastern Solomons = 30 / 4

Santa Cruz = 127 / 25 (Gatch: 5% 5in, rest CIWS)

Solomons
Nov 11-12 = 32 / 11 (approx, most CIWS)

Total = 323 / 67

I'm sure that the USN and RN staff were impressed by the above AA claims, and doubtless many in the RN must have felt that USN AA FC and weaponry was vastly superior to RN AA FC and weaponry. I suspect that the truth would have made a huge difference in how both Navies looked at their AA situation.

 

[parsifal]

Two of the 4 kamikaze strikes that you detailed, occurred when the AA escort was weakened considerably.

You cannot claim that the Aa defences were weakened. though I have yet to confirm, it may well be that CLAas were used to replce the BBs, or that the BBs were in fact replaced by the other 2 BBs attached to TF 57 (there were a total of 4 BBs under Frasers Command.

BBs were not that good as AA escorts, at5 least in the RN. with a TD of over 1000 yards, and the carriers also having a TD of over 1000 yds, they could not place effective LAA over the Carriers and could not provide effective area defence with those weapons (2pdrs and 20mm). The 5.25" were good, but were no substitute for effective LAA which they lacked. The RN rated the max effective range of the 2pdr at 1700 yds, which meant that two large ships could not provide mutually supportive fire for each other. The Americans, with their 40mm Bofors (with an effective range of over 4000 yds) could provide such mutually supportive fire. that, plus the fact that they were firing twice as many HAA with VT at roughly twice the rof (oh know here we go again....) gave them a telling advanatage, as is reported by the British Admirals on the scene at the time. they saw what was happening and reported accordingly.


In any event, if RN DDs had been effective at AA, as you claim, they should have been able to provide area defence in place of the DDs. USN DDs were considered good enough to undertake picket duties independantly (RN DDs were not), so there in itself is evidenmce of a systemic failure by the RN.

Please provide some hard evidence for your statements of RN DD ineffectiveness. The problem with small scale attacks, is that the aircraft are free to radically manoeuvre, so that no system of AA FC in existence in WW2, could hit them, except by chance and/or sheer volume of fire so this tells us nothing.

But there is hard evicdence already. Read the reports by Rawlings and Fraser. These reports by these British Admirals are very clear that AA defence in the BPF was left wanting (and by my reading mostly because the DDs were incapable of fulfilling an aeffective AA role) and that this could only addressed by re-equipoment and new fleet dispositions (which were very rigid and limiting in their arrangements) . Fraser contrasted RN AA inneffectiveness to the USN effectiveness, which he includes in his report. Its all in the book I recommended. Its the operational results that were achieved with all those gizmos you parade as so effective. the admirals that actually had to use them, once confronted with a competing and contemporary US system, in the same environment were unequivocal. They were of the opinion that the US AA defences were vastly superior. Proof enough for me

 

[RCAFson]

You cannot claim that the Aa defences were weakened. though I have yet to confirm, it may well be that CLAas were used to replce the BBs, or that the BBs were in fact replaced by the other 2 BBs attached to TF 57 (there were a total of 4 BBs under Frasers Command.

BBs were not that good as AA escorts, at5 least in the RN. with a TD of over 1000 yards, and the carriers also having a TD of over 1000 yds, they could not place effective LAA over the Carriers and could not provide effective area defence with those weapons (2pdrs and 20mm). The 5.25" were good, but were no substitute for effective LAA which they lacked. The RN rated the max effective range of the 2pdr at 1700 yds, which meant that two large ships could not provide mutually supportive fire for each other. The Americans, with their 40mm Bofors (with an effective range of over 4000 yds) could provide such mutually supportive fire. that, plus the fact that they were firing twice as many HAA with VT at roughly twice the rof (oh know here we go again....) gave them a telling advanatage, as is reported by the British Admirals on the scene at the time. they saw what was happening and reported accordingly.


In any event, if RN DDs had been effective at AA, as you claim, they should have been able to provide area defence in place of the DDs. USN DDs were considered good enough to undertake picket duties independantly (RN DDs were not), so there in itself is evidenmce of a systemic failure by the RN.



But there is hard evicdence already. Read the reports by Rawlings and Fraser. These reports by these British Admirals are very clear that AA defence in the BPF was left wanting (and by my reading mostly because the DDs were incapable of fulfilling an aeffective AA role) and that this could only addressed by re-equipoment and new fleet dispositions (which were very rigid and limiting in their arrangements) . Fraser contrasted RN AA inneffectiveness to the USN effectiveness, which he includes in his report. Its all in the book I recommended. Its the operational results that were achieved with all those gizmos you parade as so effective. the admirals that actually had to use them, once confronted with a competing and contemporary US system, in the same environment were unequivocal. They were of the opinion that the US AA defences were vastly superior. Proof enough for me

I'm afraid that I have to strongly disagree.

1st May.
Task Force 57- sailed from Leyte in -groups at
0630 and consisted .of the following ships: —
1st Battle Squadron
KING GEORGE V (Flag of CTF 57—
B.S.1), . HOWE;
' 1st Carrier Squadron , ' .
INDOMITABLE (Flag of 2nd-in-Command
' TF57—A.C.1),
VICTORIOUS, FORMIDABLE, INDEFATIGABLE;
• 4th Cruiser Squadron
SWIFTSURE (Flag of C.S.4), UGANDA, GAMBIA, EURYALUS, BLACK PRINCE;

25th Destroyer Flotilla
. GRENVILLE (Capt. 0.25), URSA, UNDINE, URCHIN, URANIA, UNDAUNTED;

4th Destroyer Flotilla . QUILLIAM (Capt. 0.4);QUEENBOROUGH, QUIBERON, QUICKMATCH,. QUALITY;

27th Destroyer Flotilla, KEMPENFELT (Capt,. 0.2);WHIRLWIND, .WESSEX.
http://www.ibiblio.org/hyperwar/UN/UK/LondonGazette/38308.pdf

so 4 CVs, 2 BBs, 5CLs, and 14 DDs.

At 1000 hours in position 23-54N, 125-10E the bombarding force comprising KING GEORGE V, HOWE, SWIFTSURE, GAMBIA and UGANDA escorted by destroyers GRENVILLE (D5), UNDINE, URCHIN, URANIA, UNDAUNTED and URSA, and EURYALUS and BLACK PRINCE, detached from the carrier force and closed Miyako at 24 knots. The carriers provided an additional CAP for this force as well as aircraft for spotting.

So 2 BBs, 5 CLs, and 6 DDs detached themselves for the bombardment mission and no additional ships replaced them; the remaining escort was reduced to 8 destroyers, to try and screen 4 fleet carriers! No wonder that Vian was criticized, as taking the CLs was a truly boneheaded decision.

The effective range of the pom-pom and 40mm bofors in eyeshooting was estimated to be 1700 yards, but by this time many RN destroyers had gyro guns sights for their pom-poms and some may have had the Simple Tachymetric Director for them as well, but the plain fact is that the BPF was tragically weakened by Vians move. The BPF was simply too weak in supporting CLs and DDs to be compared to USN Task Groups.

Effective range of director controlled pom-poms and bofors was about the same - 3500-4000 yards (the range limit of self destructing ammo).

 

[parsifal]

As of the 1st May 4 N class were added to the force temporarily increasing the Escort ratio to 5.25. I dont have much detail on this attack, just that one kamikaze broke through out of about 20 attackers and hit Indomitbale (I think)


For the attack on the 4th, you are right, there were only 8 DDs present for defence, but this really highlights their weknesses if anything. granted on that occasion the Escort ratio fell through the floor to just 2. but the DDs were ideally placed to protect the carriers, having closed right up as I suspected (I am referring to the Flag Officers reports to the Admiralty 6 June'45, of which I have copies....they are fairly easy to come by). Though these reports make repeated references to this type of gun opening fire and this destroyer being here or there, NOWHERE does it mention the 4.7s ever having ANY effect on the Kamikazes attacking. For example

"At about 1100 three small groups of bogeys were detected to the westward, and were soon followed up by a fourth. Probably 16 to 20 enemy aircraft were employed with some acting as decoys. Fighters engaged one group working round to the southward, but one Kamikaze group penetrated to the carriers and was first detected when a plane was seen diving on the Force. Analysis shows that this group escaped detection either because, in the absence of the Bombarding Force, too many of the reduced number of radar sets were fully engaged-tracking the diversionary planes and too few acting as warning sets, or else because they made a very low approach followed by a very high climb at about 15 miles range.

There were no bandits on the screen within 20 miles when at 1131 a Zeke was seen diving from a great height on to H.M.S.
FORMIDABLE and engaged by gunfire. A.C.1 there upon manoeuvred his Force under wheel at high speed by successive emergency turns. Though reported hit by close range weapons from his target, the (single) Kamikaze crashed into the flight deck of H.M.S. FORMIDABLE near the island structure arid started a large fire in the deck park of aircraft. A.C.1 manoeuvred the formation to keep in close touch with the damaged ship, whose speed was temporarily reduced to 18 knots.

At 1134 a Zeke flying from forward to aft off the starboard bow of H.M.S. INDOMITABLE was engaged by 4.5 in. guns and temporarily disappeared in cloud. It soon reappeared diving at the ship as steeply as about 60° from the starboard beam. The Force was turning to starboard at the time and H.M.S. INDOMITABLE's wheel was increased to hard over. As the plane approached it was heavily engaged by close range weapons from the ship and set on fire; it flattened out at the last moment, deck landed on the flight deck, and bounded over the side, taking the radar arrays of the port midships directors with it. The bomb appeared to explode shortly after the plane submerged.

At 1142 another Zeke dived steeply on H.M.S. INDOMITABLE whose close range weapons and those of HiM.S.. QUALITY hit him hard and often. The aircraft burst into flames and crashed into the sea about 10 yards off the starboard bow of the ship'

If you wanted to summarize these attacks, there is absolutely no mention of the 4.7s engaging, here or elsewhere in the report. The 4.5s are mentioned as engaging, but inneffective. The CIWs of the Carrier and one DD were mentioned, and appear to have been successful againt two out the three attackers, but hese attackers were pressing home their attacks singly. this is not a good look for the vaunted claim of the 4.7 being an effective AA weapon, and is also pretty clear evidence that the 2pdr was also not good at stopping Kamikazes if massed attacks had been employed

Elsewhere in this report to the Admiralty Rawlings reports

"At 1945 CTF 57 assumed tactical command. A total of 14 enemy aircraft, all airborne, were destroyed during the day by fighters, 2 shot down by gunfire"

2 shot down is not a great score, neither were the attackers thrown off their missions by the RN fire. The Brits were lucky they had armoured flight decks, otherwise they may well have lost two carriers that day. This too was noted by the admirals report.

In his book Carriers in Combat: The Air War at Sea, Chester G. Hearn notes the failings of RN AA as well. He notes the total ineffectiveness of the 4.7 as an AA weapon, and furthe the inability of the Pom Poms and the 20mm guns to act effectively against determined attackers like the Kamikazes.

T

he effective range of the pom-pom and 40mm bofors in eyeshooting was estimated to be 1700 yards, but by this time many RN destroyers had gyro guns sights for their pom-poms and some may have had the Simple Tachymetric Director for them as well, but the plain fact is that the BPF was tragically weakened by Vians move.

I agree with the last bit, and dont disagree with the 1st bit relating to the technological improvements. Still wasnt enough, even when the fleet was operating with an excess of escorts, such as on March 27, when the first attacks on Sakushima were launched, and Illustrious was hit by a Kamikaze. that failure led to the changes that saw the RN DDs ideally placed on 1 May. However Rawlings on both occasions commented on the inadequacy of the RN CIWs, gizmos or no. Both he and fraser knew they needed the 40mm bofors, and actively lobbied for US methods and Directors to be installed in their ships.

 

[RCAFson]

As of the 1st May 4 N class were added to the force temporarily increasing the Escort ratio to 5.25. I dont have much detail on this attack, just that one kamikaze broke through out of about 20 attackers and hit Indomitbale (I think)


For the attack on the 4th, you are right, there were only 8 DDs present for defence, but this really highlights their weknesses if anything. granted on that occasion the Escort ratio fell through the floor to just 2. but the DDs were ideally placed to protect the carriers, having closed right up as I suspected (I am referring to the Flag Officers reports to the Admiralty 6 June'45, of which I have copies....they are fairly easy to come by). Though these reports make repeated references to this type of gun opening fire and this destroyer being here or there, NOWHERE does it mention the 4.7s ever having ANY effect on the Kamikazes attacking. For example

"At about 1100 three small groups of bogeys were detected to the westward, and were soon followed up by a fourth. Probably 16 to 20 enemy aircraft were employed with some acting as decoys. Fighters engaged one group working round to the southward, but one Kamikaze group penetrated to the carriers and was first detected when a plane was seen diving on the Force. Analysis shows that this group escaped detection either because, in the absence of the Bombarding Force, too many of the reduced number of radar sets were fully engaged-tracking the diversionary planes and too few acting as warning sets, or else because they made a very low approach followed by a very high climb at about 15 miles range.

There were no bandits on the screen within 20 miles when at 1131 a Zeke was seen diving from a great height on to H.M.S.
FORMIDABLE and engaged by gunfire. A.C.1 there upon manoeuvred his Force under wheel at high speed by successive emergency turns. Though reported hit by close range weapons from his target, the (single) Kamikaze crashed into the flight deck of H.M.S. FORMIDABLE near the island structure arid started a large fire in the deck park of aircraft. A.C.1 manoeuvred the formation to keep in close touch with the damaged ship, whose speed was temporarily reduced to 18 knots.

At 1134 a Zeke flying from forward to aft off the starboard bow of H.M.S. INDOMITABLE was engaged by 4.5 in. guns and temporarily disappeared in cloud. It soon reappeared diving at the ship as steeply as about 60° from the starboard beam. The Force was turning to starboard at the time and H.M.S. INDOMITABLE's wheel was increased to hard over. As the plane approached it was heavily engaged by close range weapons from the ship and set on fire; it flattened out at the last moment, deck landed on the flight deck, and bounded over the side, taking the radar arrays of the port midships directors with it. The bomb appeared to explode shortly after the plane submerged.

At 1142 another Zeke dived steeply on H.M.S. INDOMITABLE whose close range weapons and those of HiM.S.. QUALITY hit him hard and often. The aircraft burst into flames and crashed into the sea about 10 yards off the starboard bow of the ship'

If you wanted to summarize these attacks, there is absolutely no mention of the 4.7s engaging, here or elsewhere in the report. The 4.5s are mentioned as engaging, but inneffective. The CIWs of the Carrier and one DD were mentioned, and appear to have been successful againt two out the three attackers, but hese attackers were pressing home their attacks singly. this is not a good look for the vaunted claim of the 4.7 being an effective AA weapon, and is also pretty clear evidence that the 2pdr was also not good at stopping Kamikazes if massed attacks had been employed

Elsewhere in this report to the Admiralty Rawlings reports

"At 1945 CTF 57 assumed tactical command. A total of 14 enemy aircraft, all airborne, were destroyed during the day by fighters, 2 shot down by gunfire"

2 shot down is not a great score, neither were the attackers thrown off their missions by the RN fire. The Brits were lucky they had armoured flight decks, otherwise they may well have lost two carriers that day. This too was noted by the admirals report.

In his book Carriers in Combat: The Air War at Sea, Chester G. Hearn notes the failings of RN AA as well. He notes the total ineffectiveness of the 4.7 as an AA weapon, and furthe the inability of the Pom Poms and the 20mm guns to act effectively against determined attackers like the Kamikazes.

T

I agree with the last bit, and dont disagree with the 1st bit relating to the technological improvements. Still wasnt enough, even when the fleet was operating with an excess of escorts, such as on March 27, when the first attacks on Sakushima were launched, and Illustrious was hit by a Kamikaze. that failure led to the changes that saw the RN DDs ideally placed on 1 May. However Rawlings on both occasions commented on the inadequacy of the RN CIWs, gizmos or no. Both he and fraser knew they needed the 40mm bofors, and actively lobbied for US methods and Directors to be installed in their ships.

C'mon...you can't seriously argue that if an kamikaze aircraft makes it through the screen, that it means the destroyers have ineffective AA because that same argument would be also damn Mk 37 and the 5in/38 because hundreds of kamikazes were able to hit USN ships despite the destroyer screens. As I said before, an aircraft flying an erratic course was an impossible target for WW2 AA FC systems, and a single aircraft can be very hard to spot, and if you can't see it you can't engage it.

 

[parsifal]

C'mon...you can't seriously argue that if an kamikaze aircraft makes it through the screen, that it means the destroyers have ineffective AA because that same argument would be also damn Mk 37 and the 5in/38 because hundreds of kamikazes were able to hit USN ships despite the destroyer screens. As I said before, an aircraft flying an erratic course was an impossible target for WW2 AA FC systems, and a single aircraft can be very hard to spot, and if you can't see it you can't engage it.

.

I dont say that, the commanders on the spot on the receiving end of those attacks say it in their reports to the Admiralty.

These are not my words. they are the words of the commanders on the spot (not the exact words, but Ive previously quoted him in preceding posts, but I am faithfully paraphrasing him). They run contrary to the case youve made i know, but that is what it is. The 4.7, the Pom, the 20mm and the british HACs system fire may be effective against a less resolute enemy (Fraser says that too), but against a ruthless, determined (if by 1945 a somewhat illtrained) enemy like the Japanese simply not up to par (Fraser recognizes that as well).

Fraser in particular in his report says that the destroyers had been designed and built for surface action, and then during the war years had been developed around the 2pdr and 20mm CIWs for close in defence. He does not mention the 4.7, but his inferences are very clear....the long range DP and its directors were inneffective in that role

As for your claims about US DDs, again I rely on the advice of Rawlings and Fraser. They thought they were very effective, so they dont agree with you assessment of inneffectiveness either. They dont agree with your summation. Paraphrasing again, but these men essentially observed the higher levels of success by the US and advocated the adoption of their methods, and technology in shipboard air defence matters. That basically meant using the Mk37 and 5/38, greater usage of the VT fuses along with the Bofors to break up the determined Japanese attacks, and tighter tactical dispositions around the high value targets. Allowed a much more highly integrated defence than had previously been the case for the RN, or even the USN in its formative stages of the doctrine.

Unpalatable as these observations are (for me as well), they are not my opinions, though I agree with them. they are the opinions of the men leading the british forces in the Pacific.

Not exactly on topic, but while these men called a spade a spade when it came to the AA defences of their fleet, and were in a position to know, they also did point out the far more advanced airborne air defence methods. The RN got a lot out of their airborne air defences. Not so their ship based air defencess (but in particular the destroyers used in that capacity).

As the war drew to a close the British upgraded their equipment and modified their procedures. according to the commanders, in their subsequent reports, things did get better as time progressed. but it had taken a while (since the outbreak of hostilities in '39).

I dont see your opinions as completely at odds with the fleet commanders of 1945. British AA defence was made adequate for the ETO, but initially was found lacking in the PTO. It staged a partial recovery, after adopting US methods and equipment (as far as possible) in a fairly short space of time.

 

[RCAFson]

As for your claims about US DDs, again I rely on the advice of Rawlings and Fraser. They thought they were very effective, so they dont agree with you assessment of inneffectiveness either. They dont agree with your summation. Paraphrasing again, but these men essentially observed the higher levels of success by the US and advocated the adoption of their methods, and technology in shipboard air defence matters. That basically meant using the Mk37 and 5/38, greater usage of the VT fuses along with the Bofors to break up the determined Japanese attacks, and tighter tactical dispositions around the high value targets. Allowed a much more highly integrated defence than had previously been the case for the RN, or even the USN in its formative stages of the doctrine.

The RN thought USN destroyers were effective because the USN said they were effective:

***

This was the official USN tally of AA kills as of the end of 1942:

From the above:

USN AA kill claims / Lundstrom verified AA kills at:

Bougainville 6 / 1 ( 2 shared AA/fighter kills)

Coral Sea = 49 / 9 (5 to Crace's RAN and USN TG, 1 to Neosho and Sims rest to carrier TG)

Midway = 20 / 3 (1 = two shared AA and fighter kills)

Solomons
Aug 7-8 = 59 / 15 (2 on Aug 7, 13 on Aug 8 mostly CIWS)

Eastern Solomons = 30 / 4

Santa Cruz = 127 / 25 (Gatch: 5% 5in, rest CIWS)

Solomons
Nov 11-12 = 32 / 11 (approx, most CIWS)

Total = 323 / 67

I'm sure that the USN and RN staff were impressed by the above AA claims, and doubtless many in the RN must have felt that USN AA FC and weaponry was vastly superior to RN AA FC and weaponry. I suspect that the truth would have made a huge difference in how both Navies looked at their AA situation.

***

The problem is that the historical record says otherwise. This is the big stumbling block that completely trashes MK 37-5in/38; in actual combat it just couldn't destroy aircraft in large numbers despite the incredible claims of the USN to the contrary. Look at the carrier versus carrier actions; Coral Sea, Midway, Eastern Solomons, where the USN relied on the MK 37 as their CIWS was very weak (yet still claimed the lions share of kills) prior to the Bofors becoming available, and the AA results were pathetic - only 10 AA kills in all 3 actions yet the USN claimed ~90 AA kills in these 3 clashes. Yet in all three actions the USN carrier TGs were well screened with their latest destroyer models and at Eastern Solomons they had the last word in Mk37 AA defence via a battleship (North Carolina) and a CLAA (Atlanta) and they still couldn't generate an effective AA defence.

 

[parsifal]

The final report by the HQ Naval headquarters CinC does not make those claims. The report is dated October 1945, so in reality was being collated from known fleet data for at least two years before that. The report makes the following conclusions regarding their AA effectiveness

"Of these, an estimated 2,773, or 36 percent, were shot down by naval and merchant ships. In addition to these, the enemy expended 314 planes and pilots in suicide crashes on ships.

AA. successes for the war by 6-month periods follow:

Period: Assessed kills
Pearl Harbor 26
First half 1942 56
Second half 1942 146
First half 1943 72
Second half 1943 300
First half 1944 171
Second half 1944 310
First half 1945 964
July and August 1945 11
Total 2,056
Armed Guard total 200
Grand total 2,256

The "kills" listed in the foregoing table occurred within sight of the ships being attacked. The 5,500 planes not shot down immediately were so harassed by antiaircraft gunfire that comparatively few were able to carry out their missions successfully. Damage to ships caused by enemy planes is outlined later in this chapter.

It has been the experience of our own aircraft with enemy AA. that 70 percent of them fell at or in the vicinity of the target. The remaining 30 percent either crashed en route back to their bases or were so badly damaged that they had to be stricken after arriving at their bases. It appears justified to conclude, therefore, that except for suicide planes, which by their nature are committed to destruction, those enemy planes which...."


I would think it highly likley that Fraser and Rawlings as foreign components of the 5th Fleet, would have seen preliminary or interim estimates of those figures at some point in 1945.

The figures contained in the final report dont look too far from the truth to me. For example, it lists 26 losses to AA over Pearl in December. That pretty much accords to other figures Ive seen. It lists 56 losses for the first half of 1942, and 146 losses for the second half. I dont know if they are correct, but they seem to accord to some other sources, including some that are Japanese (such as the tramslated book on operations in the SWPacific through to June 1943). Its hard to know how accurate these figures are, but they seem okay to me. By comparison, Ive seen RN estimates of the numbers of a/c they shot down as about 2-300. Admittedly, you have to make allowance for the vastly smaller size of the RN, and also that these figures are all very rubbery, but if even half right, it shows starkly the difference in AA performance and efficiency of the two navies.

Oveclaimimng by AA was common to both Navies, and could generally only be corrected only long after the battle
In the naval battles around Crete in May 1941, for example, attacks by German planes, mainly Ju-87 and Ju-88, destroyed three British cruisers (Gloucester, Fiji and Calcutta) and six destroyers (Kelly, Greyhound, Kashmir, Hereward, Imperial and Juno). Damage to the aircraft carrier Formidable, battleships Warspite and Barham, destroyers Kelvin and Nubian, and cruisers Ajax, Dido, Orion, and Perth kept these ships out of action for months. By 1 June the effective eastern Mediterranean strength of the Royal Navy had been reduced to two battleships and three cruisers to oppose the four battleships and eleven cruisers of the Italian Navy.

This has to be considered a major action by any standard, and in fighting that fight, the RN shipborne AA claimed for the period of 15–27 May Twenty enemy aircraft...shot down for certain, with 11 probables. At least 15 aircraft appeared to have been damaged..."; from 28 May – 1 June, another two aircraft were claimed shot shot down and six more damaged, for a total of 22 claimed destroyed, 11 probably destroyed and 21 damaged, during the entire campaign. In fact in that period, Axis admitted losses to AA were just 10 aircraft, with a lot more damaged. If the RN was influenced by USN overclaiming, why wouldnt they be similalry swayed by RN overclaimimg. it cuts both ways.



However, even thats not the point. Rawlings and Fraser were not influenced by those written estimates, at least Ive not found them mentioning them. But Webb doioes say that they observed first hand the effectiveness of USS AA, and could see straiaght away, from first hand observation that it was superior to anything they had in the BPF at that time. They dont actually say that in their reports, but in Hearns book, he says that they did press for changes to American Weaponary and tactical methods before the launching of Olympic (which of course never happened). I am convinced that fraser and rawlings formed the opinions that they did, on the basis of what they saw, and not what they were told. There is simply no evidence to support that notion. and what they saw was their own DDs not performaing that well in the fleet defence role, and US DDs sufficiently capable at AA defence as to be entrusted with the extraordinarily difficult radar picket duties independant of any real support. The British could not entrust their DDs to undertake that task on their own.

Final

 

[RCAFson]

The final report by the HQ Naval headquarters CinC does not make those claims. The report is dated October 1945, so in reality was being collated from known fleet data for at least two years before that. The report makes the following conclusions regarding their AA effectiveness

"Of these, an estimated 2,773, or 36 percent, were shot down by naval and merchant ships. In addition to these, the enemy expended 314 planes and pilots in suicide crashes on ships.

AA. successes for the war by 6-month periods follow:

Period: Assessed kills
Pearl Harbor 26
First half 1942 56
Second half 1942 146
First half 1943 72
Second half 1943 300
First half 1944 171
Second half 1944 310
First half 1945 964
July and August 1945 11
Total 2,056
Armed Guard total 200
Grand total 2,256

The "kills" listed in the foregoing table occurred within sight of the ships being attacked. The 5,500 planes not shot down immediately were so harassed by antiaircraft gunfire that comparatively few were able to carry out their missions successfully. Damage to ships caused by enemy planes is outlined later in this chapter.

It has been the experience of our own aircraft with enemy AA. that 70 percent of them fell at or in the vicinity of the target. The remaining 30 percent either crashed en route back to their bases or were so badly damaged that they had to be stricken after arriving at their bases. It appears justified to conclude, therefore, that except for suicide planes, which by their nature are committed to destruction, those enemy planes which...."

Even these numbers are a considerable overestimate, but it was the claims made by the USN in the earlier time frames that probably did the damage, in terms of creating an unjustified reputation for the MK 37, a reputation we now know is just plain false.

I would think it highly likley that Fraser and Rawlings as foreign components of the 5th Fleet, would have seen preliminary or interim estimates of those figures at some point in 1945.

The figures contained in the final report dont look too far from the truth to me. For example, it lists 26 losses to AA over Pearl in December. That pretty much accords to other figures Ive seen. It lists 56 losses for the first half of 1942, and 146 losses for the second half. I dont know if they are correct, but they seem to accord to some other sources, including some that are Japanese (such as the tramslated book on operations in the SWPacific through to June 1943). Its hard to know how accurate these figures are, but they seem okay to me. By comparison, Ive seen RN estimates of the numbers of a/c they shot down as about 2-300. Admittedly, you have to make allowance for the vastly smaller size of the RN, and also that these figures are all very rubbery, but if even half right, it shows starkly the difference in AA performance and efficiency of the two navies.

Naval AA success over Pearl Harbor were in the range of 15 aircraft. I've enumerated the USN losses for the major battles of 1942 and they fall far short of the numbers listed.

Oveclaimimng by AA was common to both Navies, and could generally only be corrected only long after the battle
In the naval battles around Crete in May 1941, for example, attacks by German planes, mainly Ju-87 and Ju-88, destroyed three British cruisers (Gloucester, Fiji and Calcutta) and six destroyers (Kelly, Greyhound, Kashmir, Hereward, Imperial and Juno). Damage to the aircraft carrier Formidable, battleships Warspite and Barham, destroyers Kelvin and Nubian, and cruisers Ajax, Dido, Orion, and Perth kept these ships out of action for months. By 1 June the effective eastern Mediterranean strength of the Royal Navy had been reduced to two battleships and three cruisers to oppose the four battleships and eleven cruisers of the Italian Navy.

This has to be considered a major action by any standard, and in fighting that fight, the RN shipborne AA claimed for the period of 15–27 May Twenty enemy aircraft...shot down for certain, with 11 probables. At least 15 aircraft appeared to have been damaged..."; from 28 May – 1 June, another two aircraft were claimed shot shot down and six more damaged, for a total of 22 claimed destroyed, 11 probably destroyed and 21 damaged, during the entire campaign. In fact in that period, Axis admitted losses to AA were just 10 aircraft, with a lot more damaged. If the RN was influenced by USN overclaiming, why wouldnt they be similalry swayed by RN overclaimimg. it cuts both ways.

Those numbers appear to come from the wikipedia article on Crete:
Battle of Crete - Wikipedia, the free encyclopedia
and you will note that the article states:

In total, Royal Navy AA gunners shot down 10 Luftwaffe aircraft and damaged 16 more, some of which crash-landed upon return to base, on 21/22 May.[55]
[55]Shores 1987, pp. 357–9. 5 Ju-87 and 5 Ju-88 aircraft were lost.

So Shores states 10 kills on May 21/22 alone. AFAIK, the article doesn't detail Luftwaffe losses from RN AA for the rest of the battle, but we can safely assume that there was losses on other days as well, so the RN estimate seems extremely accurate, especially by way of comparison with the USN in 1942. RN losses were amplified and AA successes minimized by the need to disperse the fleet, thus allowing the Luftwaffe to attack and overwhelm small numbers of ships, many of whom, such as Gloucester and Fiji, were critically short of AA ammo even before they were detached from the main body. Several ships, such as Fiji had AA FC radar during the battle, but it was still not fitted in any numbers to RN destroyers.

However, even thats not the point. Rawlings and Fraser were not influenced by those written estimates, at least Ive not found them mentioning them. But Webb doioes say that they observed first hand the effectiveness of USS AA, and could see straiaght away, from first hand observation that it was superior to anything they had in the BPF at that time. They dont actually say that in their reports, but in Hearns book, he says that they did press for changes to American Weaponary and tactical methods before the launching of Olympic (which of course never happened). I am convinced that fraser and rawlings formed the opinions that they did, on the basis of what they saw, and not what they were told. There is simply no evidence to support that notion. and what they saw was their own DDs not performaing that well in the fleet defence role, and US DDs sufficiently capable at AA defence as to be entrusted with the extraordinarily difficult radar picket duties independant of any real support. The British could not entrust their DDs to undertake that task on their own.

Final

I'm afraid that is a very narrow base upon which to rest your case. Observers of USN target practise were mislead as 5"/38 efficiency:

Heavy AA. Gun Batteries

The most outstanding deficiency in Fleet AA. in suicide actions to date has been the performance of heavy AA. batteries. Previously (1 January to 1 July 1944) accounting for 39 percent of the kills credited to AA., the performance of 5-inch batteries against suicide planes has dropped to 18 percent. This is due to two factors namely:

Failure to engage at ranges in which the primary fire control system is most effective.

Failure to utilize most effective fire control methods available.

Establishing fire control contact at long range is a function of radar search. Utilization of the fire control systems and methods available is a function of the ship's internal organization.

Existing primary fire control systems in combatant vessels (Mark 37 or 33) are designed for dual purpose functions. Their efficiency in handling a critical AA. problem accordingly suffers. Unfortunately this deficiency does not become apparent as a result of training because the towed sleeve, with which the bulk of training is of necessity performed, lends itself well to the shortcomings of the system. Analysis of extensive data on Fleet shooting in action indicates that the average error of the shooting with primary system is on the order of 10 mils at ranges beyond 6,000 yards. Inside that range errors rapidly increase, due to evasive action of the target, to 16 mils at 4,000 yards and 20 mils at 2,000 yards.
HyperWar: Antiaircraft Action Summary--Suicide Attacks [Chapter ]

 

[Glider]

The question is Was the 5in DP gun better for AA defence compared to the twin 4.7in RN destroyers gun. There is no doubt that all the RN officers who observed both in action believe that the result is yes, the 5in was a much better weapon. No one has even tried to quote an RN officer who believed that the twin 4.7 was even close to being as good as the 5in. We have opinions, theories but no quote from anyone at the time.

To base the defence against this on observations that the USN believed that the 5in wasn't as good as they liked is a different answer to a different question. I am very confident that the RN would have been absolutely delighted if their Heavy AA guns had shot down 18 percent of the suicide aircraft. To claim 39% of all kills in the period Jan - July is a remarkable achievement.