What was the most effective naval anti-aircraft gun of WW2?

[lwd]

I saw a document recently where refering to a British evaluation of the 5"38 they said that it could fire 25 rounds/ minute until the ready rounds were exhausted.

[Bgile]

I saw a document recently where refering to a British evaluation of the 5"38 they said that it could fire 25 rounds/ minute until the ready rounds were exhausted.

That is the rate of fire claimed by the North Carolina book I have.

[lwd]

Here's the reference I found:
http://www.navweaps.com/Weapons/WNUS_5-38_mk12.htm

2) The guns installed on HMS Delhi had originally been destined for USS Edison (DD-439). These guns had been hand-picked by Edison's first commanding officer, Lt. Cmdr. A. C. Murdaugh, who had just previously been assigned to the Naval Gun Factory at Washington, D.C. Much to Lt. Cmdr. Murdaugh's distress, President Roosevelt ordered these guns diverted to Delhi. Following very successful gunnery trials in February and March 1942, the gunnery officer on Delhi reported that these guns could maintain 25 rounds per minute with the ready-use ammunition stored in the handling rooms and 15 rounds per minute with the normal supply from the magazines.

[Bgile]

Here's the reference I found:
http://www.navweaps.com/Weapons/WNUS_5-38_mk12.htm

2) The guns installed on HMS Delhi had originally been destined for USS Edison (DD-439). These guns had been hand-picked by Edison's first commanding officer, Lt. Cmdr. A. C. Murdaugh, who had just previously been assigned to the Naval Gun Factory at Washington, D.C. Much to Lt. Cmdr. Murdaugh's distress, President Roosevelt ordered these guns diverted to Delhi. Following very successful gunnery trials in February and March 1942, the gunnery officer on Delhi reported that these guns could maintain 25 rounds per minute with the ready-use ammunition stored in the handling rooms and 15 rounds per minute with the normal supply from the magazines.

That is an odd quote, since the "normal supply" would be from the handling room.

[Brett]

HI

I have been surfing the web and not much on 6" guns in AA role and their actual effectiveness in battle. As some may of gathered I have an interest in what could have been had foresight along with 1930's technology being incorporated in major warships. I am certain that even had the Germans ready 5" AA they might have stuck with 6" guns had they the performance of say UK or British cruiser guns. Of all the battleship design issues the most complex is secondaries as a 5 L38 against an attacking cruiser might not cut the mustard. The Bismark 150mm did stop a cruiser so in way justified is incorporation in the design.

The web and books tend to be a mass of misinformation on many aspects of gunnery. The aircraft is said to have doomed the battleship in 1941. Yes, sitting in harbour it is an was an easy target but not as much as an aircraft carrier as typified by the debarcle by a British aircaft carrier that tried to land its aircraft when docked. The POW is seen as the tipping point but from then on it was not until the mass attacks of 1945 by the USA that a battleship was lost to aircraft. In fact you could say a submarine was more dangerous to a battleship.

Even the POW shows it took a specialist squadron trainned to sink ships and a hit in the propulsion system along with poor damage control due to bad working conditions and lack of communication to bring the ship to heel. An effective 1941 tracking system combined with high rate fire guns might of made a difference in the Bismark and POW loss to aircraft. Also had the KGV been the running mate instead of the Repluse maybe thinks might have been a little different as well, or maybe two modern battleships would have been lost. Hard call but strange if luck was the deciding factor.

I often find strong critism is levelled against gun systems and in general ship design when it is often subsidiary things like damage control or non sexy things like poor below deck working conditions and communications along with power loss that accounted for the loss of a ship. It might be careful design and trainning of crews is more important and than often over stressed designs.

Cheers Brett

[Bgile]

The USN tried automatic loading 6" AA postwar and I think determined that the increased range over 5" was largely pointless because it was just too hard to get an AA shell close to an aircraft at the increased range. Of course there were other mitigating factors as well, such as the advent of jet aircraft and troubles with the loading apparatus. It was designed to be able to switch instantly between AA and surface gunnery with two different shell feeds and it gave trouble. The Des Moines class cruisers used a similar loading system with the 8" but it was single feed and was much more reliable.

[Brett]

Hi Bgile

I have noticed a couple of post WW2 era designs with the Tiger 6" twin gun mount being the stand out but much later in the time line. While a twin load system is sexy enough to be considered a good thing by designers (handy for ground attack aircraft) however I would imagine in most engagements the suface or air target would be selected quite early in the battle. If you are unlucky enough to have battleship, crusier and aircraft coming at you it would be a busy, if short day in the office, as this would suggest you had stumbled across the main battle fleet.

I actually find the underlying reasons for decision sometimes more interesting than the actual final fighting platform. Since 1900 technology has played an increasing important role in winning or losing and while the technology has changed the poltical and human process has not. I read with interest the article between how the German Naval design department changed from WW1 to WW2 and the result. No better example is cruiser sized destroyers that on paper in 1940 would appear to have overwhelmed the smaller British design but most wound up been sunk once the small ammunition supplies and fuel ran out. Also the slow fire rate did not help and thank goodness UK air cover was not massed either against them. Yes, the usual poltical interference played a role but that is rather common and while easly blamed I do question some design decisions made long before. The crazy thing is I have read that the German Navy had planned to secure Norway as part of its battle plan for some time, predating destroyer designs. The UK designers love of larger magazines meant on the long voyages to Malta they had a fighting chance with many ships been sunk or damaged only once ammunition ran out.

I would have hoped that in 1930's the use of secondaries would have been carefully considered. The 5.25" was probably a better surface gun than the 5" USA but much the reverse for AA role. The French had bet on 6" facing the same problem of the Germans with shortage of screening ships for the battleships. British had swung largely to 6" cruiser design and the USA built very big 6" cruisers so I would have thought more information on the design of 6" as AA would be about. What information it appears for WW2 AA is, see 100mm Japanse or 5" L38 and give it to the 5" because of superior fire control. Had the Japanese managed a planned mass torpedeo attack on the USA battle line I wonder if we would be writing on how poor choice the 5" L38 was

I would think that the 8" was a bridge too far but then the County Class was designed with high elevation angle along with the Japanese 8" cruisers. Even ignoring fire control systems and loading rates it does amaze me that both were considered to slow in training speed. Makes you wonder what was the thought process? Could it be in a 8" turret high speed directon changes do not play well with crew, ie, motion sickness?

Cheers Brett

[Bgile]

Typically 8" and even 6" turrets are heavily armored and so very heavy. It's very difficult mechanically to get such a heavy turret moving fast and then stop it again. At least some of the British heavy cruisers which began with the high elevation rate 8" guns were later modified to reduce it and simplify the turret because the high elevation just wasn't very practical in actual use.

The above is the reason the USN chose 38 caliber for the 5" gun. The 5"/25 was fairly handy, but didn't generate a high enough muzzle velocity. The 5"/51 could do that, but was much heavier and moved more slowly. The 5"/38 was designed as a dual purpose weapon to engage both types of target, and it had a very high elevation and traverse rate.

As a side note, many of the USN 5"/25 guns eventually found their way onto US submarines.

[dunmunro]

HI

I have been surfing the web and not much on 6" guns in AA role and their actual effectiveness in battle.

The RN recognized that the 6" gun could be very effective in the AA role due to its heavy shell and excellent ballistics. 6" cruisers and BBs did use a fixed range barrage to deter AA attacks, but the slow RoF and elevation/training of a 6" gun made predicted fire very difficult to do. One innovation was the Auto Barrage Unit, or ABU, which allowed for radar controlled predicted fire, using preset fuze settings.

Regarding the loss of the PoW; in the Med the RN often faced similar torpedo attacks from SM79 TBs. These attacks were invariably defeated, and in Sept 1941 PoW was credited with two SM-79 kills (and a Fulmar). The RN defeated TB attacks through the use of massed predicted and barrage medium calibre AA fire, and shot down many of the TBs. Typically, there was also some fighter cover which prevented the TBs from loitering before attacking, although in several cases this was not much of a factor, compared to the massed gunfire. However, Force Z did not have a DD screen or any CLs which could direct predicted fire against the TBs, and a single battery of 5.25" guns was simply insufficient in terms of volume of fire. A proper DD screen with say 6 modern DDs with the FKC system, and a quad pom-pom each, and a couple of CLs would probably have defeated the TB attacks, or reduced their number sufficiently that the CIWS could do the rest. PoW was the only ship in Force Z with a really modern FC system and managed to damage 10 of 16 high level bombers with her 5.25"radar ranged, predicted fire. Repulse only had 4 x 4" HA guns controlled by an elderly HACS system, and the 3 DDs had no HA FC system at all. PoW's pom-poms seemed to work well in the Med, although she reported some stoppages there, but they were plagued by stoppages during her last battle. I don't know why this was the case, although there are some indicators that the ready use ammo was badly effected by the intense tropical heat. In Jan 1941, Illustrious's Pom-Pom's performed extremely well, with very few stoppages and if Illustrious's Pom-Poms had had PoW's advanced radar ranged GRU controlled directors she would have shot down many more of the attacking Stukas. Unfortunately many of PoW's radars failed prior to arrival in Singapore and she did not have enough time or local tech assistance to bring her radar systems back online before the attack. Most of the remaining radars failed after the first hit due to shock or lack of power.

[Brett]

Hi

Yet again a recurring theme that being seamingly minor events or mistakes causing critical ships or components not to be available when required. In recent reading it is almost unbelievable the number of ships that ran aground and were not available at critical times. Obviously wartime navigation was a lot harder than it first appears to this armchair Admiral. While in 1940 I can accept that designers could have easily missed the importance of redundant electrical systems (though the Germans in WW1 realised that without lights damage control was very hard in the dark confines of the ship so played blind man bluff type games as preparation) but the same theme continued into the Falklands war with loss of power condemning a ship and even in Australia the recovery of the hulk that was HMAS Melbourne revolved around on being able to start an on board generator.

Anyway back on track. Effective AA required mechanically high rate of fire, high MV and high turret training rates backed by a decent fire control system. Fast firing rates comes from either automation or light shells combined with an under deck feeding systems to keep up. The 5" L38 appears to be the sweet spot for MV and training speed but me think a mass surface attack planned by the Japanese might have showed the lack of anti ship punch. From a keyboard warrior perspective it was a shame this did not happen as we are talking “war with tears and games without frontiers” rather than the huge human cost that such an attack would have had.

Shell ballistics along with weights, MV etc was well understood in 1930's along with what a crew can handle laong with mechanical system required to train a turrent. Surely an on the ball Navy should have dropped to either a 5" solutuion or developed a 6" Tiger or even 8" Des Mona system fire rate and training speed. Ok the UK stuffed up the 4" mounts by having non rotating shell feeding systems due to budget restrictions, more than one navy had cramped turrets that compromised ROF, and it appears without fail once past 5" turret training systems were not in the hunt. Fire control systems appeared tricky for all nations in the 1930’s but one could claim that had the Germans applied more care to getting the basics right and reliability under battle conditions they should have been in 1941 with a decent system. I woukld love to read a review of what went wrong with the the Bismark in this regard. When the British attacked the Italian fleet I belive the Italian Admiral was rather amazed at the amount of ammunition expended and the lack of aircraft shot down.

Ok what were they thinking? I forgive the British as they were not planning a war and it appears that 5.25" are more a victim of a vilification campaign on the web. Ok sounds unfair but reading some USA based sites gives the impression that the USA navy was the beacon and everyone else was an amateur so run down the UK weapons systems at every chance. Err was the 25.1 great thing or not and who came up with radar? Also most of the critical surface naval battles between Germany and Britain were fought by 1941 before USA entered the war.

The USA had enough ships and building ability to optimise secondaries for AA duty and full marks for the US Navy doing this. But Germany and Japan? This puzzles me. The 155mm was an excellent anti ship gun and might have been possible with decent turret design to get it to train fast enough but if an engineer out there says you will need to rewrite the laws of physics to do this I would accept this. Japanese industry might have been the limiting factor but they did come up with other good gun systems. The Germans I simply cannot work out. Yes I accept that the 6" secondary solution was needed against ship threats but surely they could have come up with an effective AA solution that would at least work against torpedo attacks as we are talking low elevations and moderate training speeds due to slow speed required to drop a torpedo. I agree that in 1943 onward torpedo dropping speeds had improved so might have pushed 1930's designs but in the Bismark's case the arguement was put it was the slow speed that compromised the system. Err? Um? Sounds like the designers needed a little time out given that the Swordfish and even the German carrier borne torpedo bombers where bi-planes with excellent slow speed performance. Me think poor AA performance was due to mixed mountings of the 4.1" as suggested in what I have read and complete failure to come up with a high rate of fire 37mm along with not designing a 6" system at least as effective as the UK light cruiser designs.

Um? Appears that the battleship lost the battle against aircraft back in the design stage for Germany and Japan, in the UK in the implementation stage while the USA got it right with a lot of help from Sweden. Apart from Peal Habour I cannot recall the USA losing a battleship against any form of attack. This fact of history does give a rather rosy picture of USA design decisions, especially with AA performance. Did the British use battleships in a screening role against aircraft after 1944 in the Pacific and what was the result?

Cheers Brett

[dunmunro]

Here's the reference I found:
http://www.navweaps.com/Weapons/WNUS_5-38_mk12.htm

2) The guns installed on HMS Delhi had originally been destined for USS Edison (DD-439). These guns had been hand-picked by Edison's first commanding officer, Lt. Cmdr. A. C. Murdaugh, who had just previously been assigned to the Naval Gun Factory at Washington, D.C. Much to Lt. Cmdr. Murdaugh's distress, President Roosevelt ordered these guns diverted to Delhi. Following very successful gunnery trials in February and March 1942, the gunnery officer on Delhi reported that these guns could maintain 25 rounds per minute with the ready-use ammunition stored in the handling rooms and 15 rounds per minute with the normal supply from the magazines.

That is an odd quote, since the "normal supply" would be from the handling room.

This is an account of 5"/38 RoF from a post war USN DD:
"The projectileman and the powderman stand to the left of the slide, so they can dump the proj. and powdercase on the tray. Then the mount captain rams it with the hydraulic rammer. The only person directly behind the gun is the hotshellman, (one of my old billets) and you make damn certain you are just outside the recoil limit of the beastie. Some guys would slap the empty case down and out through the empty case hatch on the aft rear of the gun, I used the other method of placing my left hand directly behind the slide, letting the guns recoil push it back. When the gun recoiled the empty would eject onto the upturned palm of my left hand and into the right. Then the empty was thrown out.
My recollection of the loading machine was that it was pretty rudimentary, with no provision for recoil. Thats reaching back thirty years though, so I could be wrong.
We had brackets on the inside of the gun shield to hold extra projectiles, just a few. We could get 22 rds a minute using them, then dropped to 17 sustained due to the time for the projectile hoist to cycle. Powder was passed up to the powderman via a scuttle in the mount deck, by the powdepasser who stood on a platform beneath the mount deck.
I really cant recall what the Mk/Mod was of the hoist, it may have been different from that of the ships in WWII. Also, the crews then were larger (wartime vs peacetime) so with more people in upper handling (Ammo train path is magazine to upper handling to mount) you could move more ammo by passing some up via the powder scuttle."

[lwd]

... The 5" L38 appears to be the sweet spot for MV and training speed but me think a mass surface attack planned by the Japanese might have showed the lack of anti ship punch. ...

The trade off may also be MV vs shell weight. In any case the combination of the rate of fire and the weight of shell of the 5"38 gave them enough punch to take out attacking destroyers. Vs cruisers the main battery could be used or more properly the screening cruisers and destroyers. The US didn't seem to design battleships to fight alone and had enough ships that they were very unlikely to have to. Washington vs Kirishima was as close as it ever came from what I've read and even their Washinton started out with some DDs which helped in the initial action and had SoDak to act as a spunge for the whole action. Taken in this context the 5"38 makes a lot of sense. The British on the other hand had a empire that was spread out enough that it was not unreasonable for them to invision a Battleship being caught alone or with minimal support. Certainly for the Germans this was not only more likely but almost guaranteed.

[Bgile]

This is an account of 5"/38 RoF from a post war USN DD:
"The projectileman and the powderman stand to the left of the slide, so they can dump the proj. and powdercase on the tray. Then the mount captain rams it with the hydraulic rammer. The only person directly behind the gun is the hotshellman, (one of my old billets) and you make damn certain you are just outside the recoil limit of the beastie. Some guys would slap the empty case down and out through the empty case hatch on the aft rear of the gun, I used the other method of placing my left hand directly behind the slide, letting the guns recoil push it back. When the gun recoiled the empty would eject onto the upturned palm of my left hand and into the right. Then the empty was thrown out.
My recollection of the loading machine was that it was pretty rudimentary, with no provision for recoil. Thats reaching back thirty years though, so I could be wrong.
We had brackets on the inside of the gun shield to hold extra projectiles, just a few. We could get 22 rds a minute using them, then dropped to 17 sustained due to the time for the projectile hoist to cycle. Powder was passed up to the powderman via a scuttle in the mount deck, by the powdepasser who stood on a platform beneath the mount deck.
I really cant recall what the Mk/Mod was of the hoist, it may have been different from that of the ships in WWII. Also, the crews then were larger (wartime vs peacetime) so with more people in upper handling (Ammo train path is magazine to upper handling to mount) you could move more ammo by passing some up via the powder scuttle."

This can't be typical of WWII operation. I've seen the inside of a 5"/38 twin mount, and I've seen the diagrams of where the crew stands. The shell men stand next to the hoists, back to back between the guns and are fenced in by the powder men. There is no way a shell could be gotten off the bulkhead of the mount and transferred to him past the powder man and then loaded faster than from the hoist. There are simply too many people in the way. If he says loading time is limited by the cycle time of the hoist, it might be because there weren't enough men in the handling room to feed it at 22 rounds per minute, and the hoist doesn't cycle until there is a round in it. Postwar destroyers were often seriously undermanned.

I doubt crews could sustain really high rates of fire for very long, but I expect it was more due to drill error and exhaustion than the speed of the shell hoist.

I just realized there would also be no way to set the fuse if you were using shells from the mount, unless the hoist was turned off and stationary in the up position, and then you would have to insert the round in the fuse setter before loading it. The same guy would have to do all this.

[lwd]

Could this be a reference to different mount types? For instance the reference above (http://www.navweaps.com/Weapons/WNUS_5-38_mk12.htm)
states:

The earliest mountings as used on USS Farragut (DD-348) were pedestal mounts with the ammunition supply points located in the fixed structure behind the gun mounts. However, starting with USS Gridley (DD-380), a new base-ring mounting with integral shell hoists on the axis of the mount was introduced.
...
Single Enclosed Base Ring Mounts Britain: HMS Delhi (5): Mark 30 Mods 6, 7 and 8
...
23) HMS Delhi had enclosed Mark 30 mounts installed in positions 1, 2, 4, 5 and 6. Her forward, midships and after magazines were converted to handle 5" (12.7 cm) ammunition. The magazine formerly used for mount 3 was changed to oil tankerage. Standard US handling rooms were fitted under the mounts, with dredger hoists in each handling room used to bring up ammunition from the magazines.

There are some diagrams of the gun mounts here:
http://www.navweaps.com/Weapons/WNUS_5-38_mk12_pics.htm
As well as a picture of Dehli with 5"38s (and a lot of other pictures as well)

[Bgile]

Of great interest to me is the photo (#2) of the early war destroyer with a modern dish antenna already mounted on the director in June of 1944.