British 4.5"/45 (11.4 cm) vs American 5"/38 (12.7 cm) Mark 12

[Byron Angel]

dunmunro -
Do you plan to provide any specific references to support your many claims and assertions ..... say, from British sources like Peat, Pugh, Porteous, Larken or perhaps Marland. So far, all I see is mostly a succession of unsupported assertions (unless you consider "Andy01" a reliable source). BTW, your last post on the Mk37 misinterprets the Mk37 GFCS reference manual passage that you cited; I suggest you read it again more closely.

I'd be happy to provide some relevant HACS-related commentary from the a/m British sources, if you wish.

- - -

Meanwhile, here is a first-hand eye-witness account of HACS versus Mk37 from an American source for your consideration -
The author was Admiral Ed Hooper, then Fire Control Officer (later Gunnery Officer) aboard USS Washington in WW2. The passage is extracted from his 1964 reminiscences (on file at the US Navy Dept Historical Section) of the summer of 1942 when USS Washington was part of a USN task force operating with the British Home Fleet to cover the Murmansk convoys –

“One day, shortly after leaving the Scapa Flow channel, the Home Fleet was ordered to battle stations. As planes towing sleeves circled the column of battleships and cruisers, Commander Home Fleet would designate a ship to fire. British heavy caliber antiaircraft fire was fantastically poor. USS Tuscaloosa’s fire was close, Wichita’s highly accurate, ours tore the sleeve immediately to shreds. The performance was repeated during subsequent runs.

Our next operation found us flooded by top officers and civilians from the Admiralty. Our antiaircraft gunnery was a primary reason ...”

- - -

Once again, it seems necessary to remind you that the Mk33 and the Mk37 were completely different FC systems. As such, it is worthy of note that only in October 1942 did the percentage of US warships fitted with the Mk37 GFCS reach 50 percent in the PTO.


B

[dunmunro]

dunmunro -
Do you plan to provide any specific references to support your many claims and assertions ..... say, from British sources like Peat, Pugh, Porteous, Larken or perhaps Marland. So far, all I see is mostly a succession of unsupported assertions (unless you consider "Andy01" a reliable source). BTW, your last post on the Mk37 misinterprets the Mk37 GFCS reference manual passage that you cited; I suggest you read it again more closely.

I'd be happy to provide some relevant HACS-related commentary from the a/m British sources, if you wish.

- - -

Meanwhile, here is a first-hand eye-witness account of HACS versus Mk37 from an American source for your consideration -
The author was Admiral Ed Hooper, then Fire Control Officer (later Gunnery Officer) aboard USS Washington in WW2. The passage is extracted from his 1964 reminiscences (on file at the US Navy Dept Historical Section) of the summer of 1942 when USS Washington was part of a USN task force operating with the British Home Fleet to cover the Murmansk convoys –

“One day, shortly after leaving the Scapa Flow channel, the Home Fleet was ordered to battle stations. As planes towing sleeves circled the column of battleships and cruisers, Commander Home Fleet would designate a ship to fire. British heavy caliber antiaircraft fire was fantastically poor. USS Tuscaloosa’s fire was close, Wichita’s highly accurate, ours tore the sleeve immediately to shreds. The performance was repeated during subsequent runs.

Our next operation found us flooded by top officers and civilians from the Admiralty. Our antiaircraft gunnery was a primary reason ...”

- - -

Once again, it seems necessary to remind you that the Mk33 and the Mk37 were completely different FC systems. As such, it is worthy of note that only in October 1942 did the percentage of US warships fitted with the Mk37 GFCS reach 50 percent in the PTO.


B

It's rather pointless to discuss HACS or FKC if you don't consider Lundstrom to be a reliable source and that his analysis shows that MK33/37 was ineffective. That really has to be the starting point for any discussion on WW2 USN/RN AA.

Anecdotal stories are worthless as we have no way to judge the veracity of the account.

This account is from a gunnery officer who served as HADT CO on HMS Scylla:

https://www.world-war.co.uk/scylla_story.php

It describes, in some detail, how HACS functioned.

[dunmunro]

It is interesting that the preceived superiority of the HACS (this is a controversial point which I can set aside for now) is due to the radar. But it doesn't make HACS the better system.

Can you elaborate on the optical aid on the HACS? I am only aware of the the binocular gradticule and the strip field RF and sights receiving the output of HACT. If that's the only aids, than the inability for HACT to take in rate of change in height becomes a big problem that hinders the use of feedback.

Let say medium bomber comes in at 180kt, carrying a torpedo at 2500ft, flying straight and level. The HACS successfully tracks the target and fire is open. At this point the bomber make a shallow "dive" of 10~20 degrees to torpedo altitude (it can't just let the plane accelerate and arriving to fast at the drop off point). I think this attack profile is pretty feasible.

From the HACS, the taget will drift low show a lower bearing rate, the RF will drift out of coincidence. The quickest way to address the drift is to turn the binocular gradticule , but that is wrong as that would change the heading of the plane in the HACT. The correct solution is to essentially not do anyting (keeping the sights and RF on target manually) to the rates and use spotting correction lower the height of the burst. But that also means the feedback from the HACT is no longer useful, any further change of speed or course can't be told from the sigts drifting off.
In the Mk37, reducing the rate the target drifts off the current setting will bring the FC solution closer to reality, but in HACS, when every change in height happens, even for mild maneuver, the feedback falls apart.

For the GRUB, do you have a source on how height change is handled? Because in every account I have seen thus far, HACT only acceptes one height, so is it the current height is used or the future height which must be calculated from a sepertate intrument from current height, average projectile velocity, and target speed? Regardless of which value is used, the output from HACT cannot be used to track target that is changing height effectively.

For the point of Mk4 radar not being good for low flying aircraft, I doubt any axis aircraft could locate enemy fleet while itself is flying near the deck, furthermore it is a radar problem, let's say a mk37 has the type 285 instead, it would surely perform better than HACS using eyeshooting sight right?

HACS against torpedo bombers:

https://racmp.co.uk/wp-content/uploads/ ... Eckert.pdf

Please read HMS Ulster Queen's report of proceedings (p.23) very carefully.

GRU/GRUB (Naval Weapons of WW2):

GRUB enabled the observed angle of
presentation and target ground speed to be
applied to the HA table, whether the
observed values were from GRU or control
officer's estimates. Under windless con-
ditions and with GRUB controlling, any
form of spotting correction was far more
likely to do harm than good, but GRUB
had no wind corrector and the control
officer might have to override. He also had
to inform the GRUB operators of any
observed alteration of target's course,
warning them that a new setting of the
presentation follow up handwheel was
necessary.

If the target was seen to climb or dive,
continuous operation of presentation
follow up and target speed handwheels was
ordered by the control officer. The design
of GRUB assumed straight and level flight
and it could generate fresh rates auto-
matically only as long as level flight was
maintained. GRU could still measure
vertical and lateral rates if the target was
not in level flight and GRUB could be set
to give these rates by fictitious speed and
target plan inclination. These in turn gave
deflections acceptable for small angles of
climb and dive.

[dunmunro]

For the GRUB, do you have a source on how height change is handled? Because in every account I have seen thus far, HACT only acceptes one height, so is it the current height is used or the future height which must be calculated from a sepertate intrument from current height, average projectile velocity, and target speed? Regardless of which value is used, the output from HACT cannot be used to track target that is changing height effectively.

For the point of Mk4 radar not being good for low flying aircraft, I doubt any axis aircraft could locate enemy fleet while itself is flying near the deck, furthermore it is a radar problem, let's say a mk37 has the type 285 instead, it would surely perform better than HACS using eyeshooting sight right?

The HACT supervised by an officer (OIC). If the target was flying a straight course at a steady speed, but changing altitude at a reasonably steady rate, he would lower the target height setting on the HACT to anticipate target height for the next salvo to be fired. For example The target height is changing by 50FPS and salvo intervals are 6 seconds anf ToF is 6secs, the OIC would lower the altitude by 600ft so that the salvo will be fuzed for the anticipated height of the target. He could also adjust target speed to allow for changes in range. We have to remember that the operators had a very good understanding of the theory of operation of the HACT and the geometries involved. GRUB would essentially do the same thing.

The HACT was setup to allow it's operators to manually intervene when ever they deemed it appropriate.

Axis aircraft acquired ASV radar from 1941-43. ASV radar could spot a ship at night well before it had to come into effective 5In range. The aircraft would measure the target's speed, course and range, and then either dive to intercept at low altitude to make the torpedo attack, or the command accompanying aircraft to make the attack whilst it observed the target and continually reported it's position to the attacking aircraft.

[dunmunro]

d

Meanwhile, here is a first-hand eye-witness account of HACS versus Mk37 from an American source for your consideration -
The author was Admiral Ed Hooper, then Fire Control Officer (later Gunnery Officer) aboard USS Washington in WW2. The passage is extracted from his 1964 reminiscences (on file at the US Navy Dept Historical Section) of the summer of 1942 when USS Washington was part of a USN task force operating with the British Home Fleet to cover the Murmansk convoys –

“One day, shortly after leaving the Scapa Flow channel, the Home Fleet was ordered to battle stations. As planes towing sleeves circled the column of battleships and cruisers, Commander Home Fleet would designate a ship to fire. British heavy caliber antiaircraft fire was fantastically poor. USS Tuscaloosa’s fire was close, Wichita’s highly accurate, ours tore the sleeve immediately to shreds. The performance was repeated during subsequent runs.

Our next operation found us flooded by top officers and civilians from the Admiralty. Our antiaircraft gunnery was a primary reason ...”

The only time that DoY and Washington exercised AA fire together was:

From: 1200 April 6, 1942 to 1200 April 7, 1948.
(a) Moored in Scapa Flow.

(b) HMS Renown and USS WASP stood out. Commander-in-Chief, Home
Fleet, made official call on Comtaskfor 39. At 1113 underway in
company with DUKE OF YORK and six destroyers for gunnery practice.
OTC Vice-Admiral in DUKE OF YORK,. Steamed at various courses and
speeds in Flow operating area.

From: 1200 April 7, 1942 to 1200 April 8, 1942.

(a) Fired 80 rounds of 5"/38 anti-aircraft ammunition, AATP-S,
port and starboard batteries, at sleeve towed by British plane.
fired 1"1, 20mm, and .50 cal. machine gun batteries at sleeve.

DUKE OF YORK fired secondary battery at same sleeve. Total
ammunition fired: 806 rounds .50 cal., 514 rounds 20mm, 185
rounds 1"1. Starboard paravane line carried away. Recovered
paravane. Fired 48 rounds 5"/38 cal. at surface target, Day
Spotting Practice, following DUKE OF YORK on each run. Held
main battery tracking exercise on KENT. RAF Spitfires made
simulated attack to train lookouts, target designators, and
secondary battery. Held instruction of officers and mount cap-
tains of anti-aircraft battery in plane identification, using
British films of British and German planes. Moored to Buoy "E",
Scapa Flow, at 2114. Morning of 8th HMS VICTORIOUS stood in and
anchored. WICHITA and TUSCALOOSA stood out for gunnery practices.

(BB56 War diary)

So Hooper's memory was faulty as per the dates and the presence of WICHITA and TUSCALOOSA. No mention of the sleeve being shot down.

[Byron Angel]

It's rather pointless to discuss HACS or FKC if you don't consider Lundstrom to be a reliable source and that his analysis shows that MK33/37 was ineffective. That really has to be the starting point for any discussion on WW2 USN/RN AA.

>>>>> If you are referring to Lundstrom’s books “The First Team” and “The First Team and the Guadalcanal Campaign”, please point to me where Lundstrom discusses naval anti-aircraft defence in any detail – page references, please. Both of these books focus almost exclusivel upon naval air combat. Parshall & Tully’s “Shattered Sword” is actually a better resource, but they deal almost exclusively with IJN anti-aircraft defence, where they deal with anti-aircraft defence at all.

However, all these books are SECONDARY SOURCES, so I am not sure how these can be reasonably deemed as “the starting point for any discussion on WW2 USN/RNH AA. Do any of the three afore-mentioned books even reference HACS/FKC in any respect at all? I don’t think so.

If you really seek a proper “starting point”, I’d suggest the works of Pugh, Peat, Porteous, Larken, Marland – who all wrote from a position of informed in-house familiarity and do a good job laying out the shortcomings of HACS/FKC. How about DK Brown (DNC)? How about Edgar March?

Here as well are a couple of USN documents related to AAW that you might want to chase down –

Information Bulletin No. 20
Antiaircraft Action Summary covering antiaircraft actions from Pearl Harbor to Dutch Harbor.
December 1941 to July 1942.

Information Bulletin No. 22
Antiaircraft Action Summary covering antiaircraft actions from Dutch Harbor to the Second December 7th.
July 1942 to December 1942.

Among other things, these documents are helpful in laying out the various issues affecting USN long-range anti-aircraft defence. At Coral Sea IIRC only two of sixteen American warships were fitted with Mk37; the task force in general were short of FC radars, which were only then starting to ramp up in production. It was not until Santa Cruz in Oct 1942 that the number of ships fitted with MK37 surpassed 50pct, and, even as late as Nov 1942 there were still a few USN ships in the PTO lacking Mk4 FC radar - the version best suited for AA fire control.

Of additional note is Admiral Nimitz’s commentary regarding the October 1942 Battle of Santa Cruz as the first occasion during the war in which shipboard anti-aircraft fire accounted for more kills than CAP fighters (Nimitz attributed this in large part to the proliferation of 40mm medium AA). The USN was aware of the drastic over-claiming; they also understood how difficult it was to fix exact loss figures. In the case of Santa Cruz, the AAR’s of all the participating ships and fighter units were closely scrutinized on an operation research basis and an estimate of 123 Japanese aircraft losses was established. Post-war Japanese testimony gives credence to this figure, per USSBS (Pacific) Interrogation of Japanese Officials, Volume 1 OPNAV-P-O3-100, Naval Analysis Division, page 79 – Interrogation of Cdr OKUMIYA, Masatake.

Question –
“How many planes did the aircraft carrier normally carry?

Answer:
SHOKAKU - - -27VF + 27VB + 18 VT
ZUIKAKU - - - 27VF + 18VB + 18 VT
ZUIHO - - - - - 21VF + 0VB + 6VT
JUNYO - - - - -18VF + 18VB + 9VT
-----------------------------------------------------
TOTAL = 216 A/C
About 2/3 were lost. Total lost about 100.

- - -

Anecdotal stories are worthless as we have no way to judge the veracity of the account.

>>>>> Please. Hooper was a long-time career naval officer, a trained gunnery specialist and retired with the rank of admiral. He was a physical eye-witness to the event. He and his papers are in the USN Historical archive.

- - -

This account is from a gunnery officer who served as HADT CO on HMS Scylla:
https://www.world-war.co.uk/scylla_story.php
It describes, in some detail, how HACS functioned.

>>>>> Yes, it is a very nicely written account about how HACS worked, but not about how effective it was in practical terms. I presume that, because he is English, he is exempt from the “anecdotal story” indictment.

Here is a statement from another RN gunnery specialist, Commander E T Larken, who not only had “hands-on” combat experience with HACS (Gunnery Officer – HMS Ark Royal), but also went on to become part of the DNO HACS development team in January 1942 –

“Undoubtedly there was a great deal of shooting … that went on in the war with the aid of HACS and FKC. In fact what happened was that a large number of bursts were put up in the vicinity of the enemy aeroplane and by hazard one occasionally hit it and shot it down; but I have seen a number of aircraft engagements and the wildness of the shooting produced with their assistance was quite staggering. One would see a formation of aircraft coming, and the bursts would appear all over the sky. That is no exaggeration. The reason for that … is the extremely cumbrous nature of the system.”

Larken then goes on to further relate –
“… the systems we had were quite hopeless” and that IP’s very poor opinion of them “was not overdoing it. They were really hopeless. I tried myself. I had seen the Ark Royal with the HACS and the most modern mark [of it]. It was terribly difficult with this enormous number of men – 19 or so in the crew – to get them all doing the right things at the right time. You required a degree of training which was practically impossible to reach in wartime.”

- - -

[Byron Angel]

d

Meanwhile, here is a first-hand eye-witness account of HACS versus Mk37 from an American source for your consideration -
The author was Admiral Ed Hooper, then Fire Control Officer (later Gunnery Officer) aboard USS Washington in WW2. The passage is extracted from his 1964 reminiscences (on file at the US Navy Dept Historical Section) of the summer of 1942 when USS Washington was part of a USN task force operating with the British Home Fleet to cover the Murmansk convoys –

“One day, shortly after leaving the Scapa Flow channel, the Home Fleet was ordered to battle stations. As planes towing sleeves circled the column of battleships and cruisers, Commander Home Fleet would designate a ship to fire. British heavy caliber antiaircraft fire was fantastically poor. USS Tuscaloosa’s fire was close, Wichita’s highly accurate, ours tore the sleeve immediately to shreds. The performance was repeated during subsequent runs.

Our next operation found us flooded by top officers and civilians from the Admiralty. Our antiaircraft gunnery was a primary reason ...”

The only time that DoY and Washington exercised AA fire together was:

From: 1200 April 6, 1942 to 1200 April 7, 1948.
(a) Moored in Scapa Flow.

(b) HMS Renown and USS WASP stood out. Commander-in-Chief, Home
Fleet, made official call on Comtaskfor 39. At 1113 underway in
company with DUKE OF YORK and six destroyers for gunnery practice.
OTC Vice-Admiral in DUKE OF YORK,. Steamed at various courses and
speeds in Flow operating area.

From: 1200 April 7, 1942 to 1200 April 8, 1942.

(a) Fired 80 rounds of 5"/38 anti-aircraft ammunition, AATP-S,
port and starboard batteries, at sleeve towed by British plane.
fired 1"1, 20mm, and .50 cal. machine gun batteries at sleeve.

DUKE OF YORK fired secondary battery at same sleeve. Total
ammunition fired: 806 rounds .50 cal., 514 rounds 20mm, 185
rounds 1"1. Starboard paravane line carried away. Recovered
paravane. Fired 48 rounds 5"/38 cal. at surface target, Day
Spotting Practice, following DUKE OF YORK on each run. Held
main battery tracking exercise on KENT. RAF Spitfires made
simulated attack to train lookouts, target designators, and
secondary battery. Held instruction of officers and mount cap-
tains of anti-aircraft battery in plane identification, using
British films of British and German planes. Moored to Buoy "E",
Scapa Flow, at 2114. Morning of 8th HMS VICTORIOUS stood in and
anchored. WICHITA and TUSCALOOSA stood out for gunnery practices.

(BB56 War diary)

So Hooper's memory was faulty as per the dates and the presence of WICHITA and TUSCALOOSA. No mention of the sleeve being shot down.

How exactly you have determined from the above log entry that Hooper was guilty of a faulty memory is quite a remarkable thing. Wow.

B

[dunmunro]

It's rather pointless to discuss HACS or FKC if you don't consider Lundstrom to be a reliable source and that his analysis shows that MK33/37 was ineffective. That really has to be the starting point for any discussion on WW2 USN/RN AA.

>>>>> If you are referring to Lundstrom’s books “The First Team” and “The First Team and the Guadalcanal Campaign”, please point to me where Lundstrom discusses naval anti-aircraft defence in any detail – page references, please. Both of these books focus almost exclusivel upon naval air combat. Parshall & Tully’s “Shattered Sword” is actually a better resource, but they deal almost exclusively with IJN anti-aircraft defence, where they deal with anti-aircraft defence at all.

However, all these books are SECONDARY SOURCES, so I am not sure how these can be reasonably deemed as “the starting point for any discussion on WW2 USN/RNH AA. Do any of the three afore-mentioned books even reference HACS/FKC in any respect at all? I don’t think so.

If you really seek a proper “starting point”, I’d suggest the works of Pugh, Peat, Porteous, Larken, Marland – who all wrote from a position of informed in-house familiarity and do a good job laying out the shortcomings of HACS/FKC. How about DK Brown (DNC)? How about Edgar March?

Yes, Lundstrom is a secondary source that had access to the combat records of both sides and was thus in a position to evaluate each aircraft's cause of loss. Lundstrom was doing an operational analysis of USN AA effectiveness. We have to look to look at how effective USN AA FC actually was versus what the USN Buord claimed it was. Once we know the probably cause of each aircraft's loss then we can use the data provided by Buord and the USN action reports to evaluate the rounds needed per aircraft kill. However, it's pretty clear that you don't want to go there because it shows how BuOrd grossly inflated 5in/38 kill rates.

Here is a statement from another RN gunnery specialist, Commander E T Larken, who not only had “hands-on” combat experience with HACS (Gunnery Officer – HMS Ark Royal), but also went on to become part of the DNO HACS development team in January 1942 –

“Undoubtedly there was a great deal of shooting … that went on in the war with the aid of HACS and FKC. In fact what happened was that a large number of bursts were put up in the vicinity of the enemy aeroplane and by hazard one occasionally hit it and shot it down; but I have seen a number of aircraft engagements and the wildness of the shooting produced with their assistance was quite staggering. One would see a formation of aircraft coming, and the bursts would appear all over the sky. That is no exaggeration. The reason for that … is the extremely cumbrous nature of the system.”

Ark Royal had the very first variant of HACS IV and was never fitted with AA radar. However, Lundstrom shows that this statement is applicable to Mk33/37 as well: "...a large number of bursts were put up in the vicinity of the enemy aeroplane and by hazard one occasionally hit it and shot it down..." since the rounds per 5in/38 kill was certainly more than 1000-1.

[dunmunro]

d

Meanwhile, here is a first-hand eye-witness account of HACS versus Mk37 from an American source for your consideration -
The author was Admiral Ed Hooper, then Fire Control Officer (later Gunnery Officer) aboard USS Washington in WW2. The passage is extracted from his 1964 reminiscences (on file at the US Navy Dept Historical Section) of the summer of 1942 when USS Washington was part of a USN task force operating with the British Home Fleet to cover the Murmansk convoys –

“One day, shortly after leaving the Scapa Flow channel, the Home Fleet was ordered to battle stations. As planes towing sleeves circled the column of battleships and cruisers, Commander Home Fleet would designate a ship to fire. British heavy caliber antiaircraft fire was fantastically poor. USS Tuscaloosa’s fire was close, Wichita’s highly accurate, ours tore the sleeve immediately to shreds. The performance was repeated during subsequent runs.

Our next operation found us flooded by top officers and civilians from the Admiralty. Our antiaircraft gunnery was a primary reason ...”

The only time that DoY and Washington exercised AA fire together was:

From: 1200 April 6, 1942 to 1200 April 7, 1948.
(a) Moored in Scapa Flow.

(b) HMS Renown and USS WASP stood out. Commander-in-Chief, Home
Fleet, made official call on Comtaskfor 39. At 1113 underway in
company with DUKE OF YORK and six destroyers for gunnery practice.
OTC Vice-Admiral in DUKE OF YORK,. Steamed at various courses and
speeds in Flow operating area.

From: 1200 April 7, 1942 to 1200 April 8, 1942.

(a) Fired 80 rounds of 5"/38 anti-aircraft ammunition, AATP-S,
port and starboard batteries, at sleeve towed by British plane.
fired 1"1, 20mm, and .50 cal. machine gun batteries at sleeve.

DUKE OF YORK fired secondary battery at same sleeve. Total
ammunition fired: 806 rounds .50 cal., 514 rounds 20mm, 185
rounds 1"1. Starboard paravane line carried away. Recovered
paravane. Fired 48 rounds 5"/38 cal. at surface target, Day
Spotting Practice, following DUKE OF YORK on each run. Held
main battery tracking exercise on KENT. RAF Spitfires made
simulated attack to train lookouts, target designators, and
secondary battery. Held instruction of officers and mount cap-
tains of anti-aircraft battery in plane identification, using
British films of British and German planes. Moored to Buoy "E",
Scapa Flow, at 2114. Morning of 8th HMS VICTORIOUS stood in and
anchored. WICHITA and TUSCALOOSA stood out for gunnery practices.

(BB56 War diary)

So Hooper's memory was faulty as per the dates and the presence of WICHITA and TUSCALOOSA. No mention of the sleeve being shot down.

How exactly you have determined from the above log entry that Hooper was guilty of a faulty memory is quite a remarkable thing. Wow.

B

Hooper states it was summer, but it wasn't further he claims the cruisers participated when they didn't.

[dunmunro]

Information Bulletin No. 20
Antiaircraft Action Summary covering antiaircraft actions from Pearl Harbor to Dutch Harbor.
December 1941 to July 1942.

Information Bulletin No. 22
Antiaircraft Action Summary covering antiaircraft actions from Dutch Harbor to the Second December 7th.
July 1942 to December 1942.

Among other things, these documents are helpful in laying out the various issues affecting USN long-range anti-aircraft defence. At Coral Sea IIRC only two of sixteen American warships were fitted with Mk37; the task force in general were short of FC radars, which were only then starting to ramp up in production. It was not until Santa Cruz in Oct 1942 that the number of ships fitted with MK37 surpassed 50pct, and, even as late as Nov 1942 there were still a few USN ships in the PTO lacking Mk4 FC radar - the version best suited for AA fire control.

Of additional note is Admiral Nimitz’s commentary regarding the October 1942 Battle of Santa Cruz as the first occasion during the war in which shipboard anti-aircraft fire accounted for more kills than CAP fighters (Nimitz attributed this in large part to the proliferation of 40mm medium AA). The USN was aware of the drastic over-claiming; they also understood how difficult it was to fix exact loss figures. In the case of Santa Cruz, the AAR’s of all the participating ships and fighter units were closely scrutinized on an operation research basis and an estimate of 123 Japanese aircraft losses was established. Post-war Japanese testimony gives credence to this figure, per USSBS (Pacific) Interrogation of Japanese Officials, Volume 1 OPNAV-P-O3-100, Naval Analysis Division, page 79 – Interrogation of Cdr OKUMIYA, Masatake.

Question –
“How many planes did the aircraft carrier normally carry?

Answer:
SHOKAKU - - -27VF + 27VB + 18 VT
ZUIKAKU - - - 27VF + 18VB + 18 VT
ZUIHO - - - - - 21VF + 0VB + 6VT
JUNYO - - - - -18VF + 18VB + 9VT
-----------------------------------------------------
TOTAL = 216 A/C
About 2/3 were lost. Total lost about 100.

- - -

Lundstrom's assessment was that IJNAF losses totaled about 100 aircraft, but AA accounted for only 25 and that the vast majority of these were via the close range autocannon AA (CIWS). (BuOrd awarded 127 AA kills as per Bulletin 22 , which was more than the observed number of IJN attack aircraft.) The largest direct killer was the USN escort and CAP fighters with the remaining aircraft lost by ditching or aboard damaged carriers.

This is from
Information Bulletin No. 22 Antiaircraft Action Summary covering antiaircraft actions from Dutch Harbor to the Second December 7th.
July 1942 to December 1942. ( I obtained copies of all the AA Bulletins published in WW2) regarding Santa Cruz:

Commander South Pacific, Admiral W. F. Halsey, U. S. N.

I consider that the 5" AA. battery is more effective than is indicated by the more extreme of the condemnatory comments in the various reports herein, | However, it is my opinion that exceptional effectiveness has been demonstrated by the 40-mm. class of AA. weapon. These should be supplied all combatant ships in maximum possible numbers-particularly carriers, but it is not believed that 5" AA. weapons should be eliminated from our CV's. Horizontal bombing attacks are best countered by 5" batteries....

...Fighters have proved to be far more effective than AA. fire against enemy aircraft and should press home attacks until forced to retire by AA. fire. Enemy planes being closely pursued and attacked by own fighters should not be fired upon. - The decision as to when to break off must rest with the fighter pilot.

So there there were claims that 5in AA was ineffective.

These ships had the most up to date Mk37 GFCS at Santa Cruz:

USS Hornet reported that her Mk37 directors could not track targets and further stated:

"...Unless 5" guns are mounted so that they can be trained from beam to beam they are of little value, 'Carriers will invariably maneuver to avoid both dive bombers and torpedo planes, . It is strongly recommended that all 5" non centerline guns be replaced by an equal number of 40-mm, mounts. . Carriers must depend upon screening vessels for protection against horizontal bombing attacks..."

South Dakota:

...on the first dive bombing attack on the Enterprise, director 4 tracked diving planes with radar ranges and placed effective bursts in their line of dive. | This firing was the only opportunity for tracking. - One plane was seen destroyed and it is believed that considerable protection was given to he Enterprise...
(b) Ammunition expended

5in- 890 rounds.
40-mm - 4,000 rounds.
1.1in. 3,000 rounds.
20mm 52,000 rounds.


(d) Effectiveness of gunnery.

(1) The antiaircraft fire of this ship was extremely effective, 'The 20-mm. guns expended about 15 magazines per gun, - Many Jap planes, after diving on the Enterprise, pulled out over this ship at ranges from 200-500 yd. - Each plane was taken under fire by several machine guns,the great majority promptly burst into flames and crashed, many of them close aboard. The
5" battery was in general handicapped by inability to track planes due to low-lying clouds, the short ranges at which planes first appeared, and by the extremely rapid maneuvering of this ship. - The 40 mm. and 1.1in quads were similarly affected but to a lesser degree, Some planes are reported to have been shot down by these batteries. It is, of course, impossible accurately to estimate the number of planes destroyed by each battery when so many guns were firing on
the same plane. - Rough effectiveness estimates during this particular engagement would be:

65% 20-mm.
35% 40-mm, and 1.1in
5% - 5in

So primarily barrage fire and Gatch's estimate of 5in effectiveness is telling.

USS Juneau:

- Radar. -Fire-control radar was not used at any time because of the multiplicity of targets, and the short ranges fired at, which prevented much normal tracking, and necessitated the use of barrage fire throughout most of the attack. It is thought that the use of the search radar to pick up torpedo planes while still at long ranges might have resulted in a little earlier warning of their approach and earlier opening of fire.

Fire Control Methods.,

5" Battery.-Planned barrage and tracking methods were followed and are considered sound. - The primary difficulties encountered were caused by radical maneuvers of own ship and fouling of range by other ships in own formation.

ammo expended
5in - 665 rnds
1.1in - 1654
20mm - 1500

So Juneau's MK37 GFCS used barrage fire just like HACS.

USS San Diego:

Operation of Fire Control Equipment,

The excellent fire-control installation for the 5" antiaircraft battery in this vessel could not be used effectively at any time due to frequent maneuvering necessary to maintain our position in the close antiaircraft screen and while circling the Hornet. - It is believed that the effectiveness of the 5" battery, which must be our main reliance in shooting down attacking planes before they can drop their bombs or torpedoes, was almost completely nullified by the necessity for frequent and radical maneuvering while firing...

USS San Juan

Comment on Several Phases of the Action.

The first dive-bombing attack on the task force lasted about 6 minutes. | During the attack the visibility was good and the ceiling was fairly high, giving a good opportunity to take the planes under fire at fairly long ranges, - As a result this attack appeared to have been repelled with less damage to the ships of the task force than was sustained in the last dive-bombing attack where visibility conditions were much poorer.

The torpedo attack only lasted 2 or 3 minutes but due to the dark, low-lying clouds on the horizon, the planes were able to approach quite close to their targets before being taken under fire. - It was during this attack that the U, 8. S, Smith had a burning plane fall on its forecastle and explode.

The second dive-bombing attack lasted about 9 minutes. During this attack the task
force was under a ceiling of low-lying clouds. - At the start of the attack the force was in a slight rain squall, ceiling about 500 feet. | The rain stopped almost as the attack began and the ceiling raised to between 1,000 to 1,500 feet during the action.. As a result of this low ceiling, the 5" AA. batteries were quite ineffective, since with a fuse setting of 1.2 seconds the shell were bursting about 3,000 feet overhead, many of them above the clouds, The enemy planes dove through the clouds, picked up their targets, dove in and dropped their bombs in a matter of
only a few seconds, | As a result, even the machine-gun fire was quite handicapped due to the short time available for picking up and shooting at targets...

Ammunition expended. -
5"/38, 886 rounds.
1.1in, 1,504 rounds,
20-mm., 4,449 rounds.

So some 5in predicted fire but mostly barrage fire. The above five ships all had MK37 and collectively fired over 3000 rnds of 5in AA. They mostly used barrage fire, which would have been used by HACS as well. There was little opportunity for long range predicted fire against aircraft, but, of course, HACS could have done that as well.

[dunmunro]

Correction from above: South Dakota's estimate of weapon effectiveness:
"65% 20-mm.
30% 40-mm, and 1.1in
5% - 5in"


Santa Cruz - Lundstrom's comments:

Lundstrom's summary of Kincaid's report:

On 30 October Admiral Kinkaid provided a summary of damage inflicted by his carriers on 26 October:

Air Group Ten (Enterprise)
2 hits on a Shōkaku-class CV
2 hits on a Kongō-class BB
26 planes shot down (air to air)
25 planes by TF-16 AA

Hornet Air Group
4–6 hits on a Shōkaku-class CV
5 hits on a Tone-class CA
4 hits on a second Tone-class CA
3 torpedo hits on a Nachi-class CA
41 planes shot down (air to air)
23 planes by TF-17 AA

So Kincaid's assessment was 48 aircraft downed by AA and 67 via air to air combat, yet BuOrd awarded 127 AA kills!


Lundstrom's summary:

Interestingly, the potency of AA at the battle became a bone of contention between veterans of the Enterprise and the South Dakota. Some sources (but significantly not the South Dakota’s action report) ascribed twenty-six kills to the battlewagon alone.(45) Without going into detail it is possible, based on all available sources, including Japanese, to offer a reasoned estimate of relative effectiveness of AA versus the CAP in destroying Japanese planes. Counting only aircraft believed destroyed in the vicinity of the two U.S. task forces, the ratio between CAP and AA kills counting all the raids was twenty-nine by aircraft to twenty-five by AA (see table 22.1).That the fierce AA did not actually finish nearly as many Japanese aircraft as estimated in no way diminished its role in ruining the attacker’s accuracy.

extracted from a table of IJNAF losses:

IJNAF overall summary for 26 Oct 1942:
total aircraft- 203
shot down- 67 (all causes including 25 AA kills)
Ditch/crashed- 28 (in the vicinity of IJN carriers as flight deck damage hampered recovery)
bombed on ships- 4

Lundstrom devoted 6 chapters of his First Team, 2nd Volume to Santa Cruz and goes into much greater detail regarding aircraft losses than the above.

[dunmunro]

USS Hornet:
Ammunition expended. -
5"/38, 205 rounds.(mostly via local control)
1.1in, ~1050 rounds,
20-mm., ~600 rnds/gun x 32 = ~18600

USS San Diego:
Ammunition expended. -
5"/38, 945 rounds.
1.1in, 3200 rounds,
20-mm., 6000 rounds.
30cal (.3in) 1500

Total 5in/38 AA at Santa Cruz for
Hornet - 205
South Dakota - 890
Juneau - 665
San Diego - 945
San Juan -886
Total = 3591. Number of 5in kill claims by above ships = 1.

[wmh829386]

Of course radar is a definite advantage, but it does not change the the problem with HACS using fictitious speed and heading to correct for the ballistic effect of wind and the inability for HACT to feedback the change of height to the sights means that the feedback system used in HACS are often ineffective. The need to use fictitious input while controlling with GRU just further illustrates the point: even though wind at altitude cannot be measured, a ballistic correction should not interfere with the tracking data in the FC system.

It seems to me very difficult to justify HACS is equal or superior to Mk37/Mk1. You may argue that HACS Mk IV with Type 285 is better than Mk37 with optical RF. But that's just illustrates how revolutionary radar was.

For the examples of engagement, I am not sure how comparable is it between kills of land based twin engine bomber and naval based single engine bomber. The number of planes and organization of the attack can post various degree of challenge to the AA batteries. The problem is further compound by the effectiveness target distribution and weather. In the case of the success from HMS Scylla, the attacking planes were designated to the director long before effective gun range and maintain height and course in a single large group. It's not hard to imagine that MK37/Mk1 with radar would perform even better at similar engagements.

[José M. Rico]

It seems to me very difficult to justify HACS is equal or superior to Mk37/Mk1. You may argue that HACS Mk IV with Type 285 is better than Mk37 with optical RF. But that's just illustrates how revolutionary radar was.

The following is from ADM 220/221:

"The Type 285 set has had to fight exclusively the long range A.A. battles of the war. In addition to having the same disadvantages enumerated for the Type 284, it has also had the crippling disadvantage for A.A. fire of being unable to track in elevation, thus virtually preventing any form of A.A. controlled blind fire. An effort was made to overcome these disadvantages by the provision of an E.P.I. (such as is used with the Type 275) or a suitably modified L.22 scope to give a form of elevation presentation. With the end of the war, however, the project was abandoned, owning to the work required to permit the aerial to be elevated separately from the director and the highly skilled operation required in return for a possible elevation accuracy of +/- 30º.

As scrutiny of the ship fitting position reveals, however, there will be a large number of Type 285's in the post war fleet, and this or some other scheme may be raised again to overcome the fundamental disadvantage of the set."

[dunmunro]

It seems to me very difficult to justify HACS is equal or superior to Mk37/Mk1. You may argue that HACS Mk IV with Type 285 is better than Mk37 with optical RF. But that's just illustrates how revolutionary radar was.

The following is from ADM 220/221:

"The Type 285 set has had to fight exclusively the long range A.A. battles of the war. In addition to having the same disadvantages enumerated for the Type 284, it has also had the crippling disadvantage for A.A. fire of being unable to track in elevation, thus virtually preventing any form of A.A. controlled blind fire. An effort was made to overcome these disadvantages by the provision of an E.P.I. (such as is used with the Type 275) or a suitably modified L.22 scope to give a form of elevation presentation. With the end of the war, however, the project was abandoned, owning to the work required to permit the aerial to be elevated separately from the director and the highly skilled operation required in return for a possible elevation accuracy of +/- 30º.

As scrutiny of the ship fitting position reveals, however, there will be a large number of Type 285's in the post war fleet, and this or some other scheme may be raised again to overcome the fundamental disadvantage of the set."

We've discussed this in the thread. In practise the USN MK IV FD radar could rarely track in elevation (and rarely at all) until 1943 when it's reliability problems were mostly overcome. OTOH, it's inability to provide elevation data below 10 degrees was never overcome, except by fitting a secondary radar in 1944. AA blind fire didn't really become an issue until the Axis introduced ASV radar enabling night detection and tracking of Allied ships. As I explained the RN had developed work arounds to engage low flying TBs at night with Type 285 radar by that time. Although there were some successes Luftwaffe night attacks were not a major issue, and certainly not a "crippling disadvantage".