Royal navy A.A.gunnery.

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

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

to which I must reply

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

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

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


re Action in the MED post 15 and 16

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

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

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

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

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

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


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

Maury had a Mk33:

Talk about the pot calling the kettle black...
 
RCAFson,

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


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


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

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

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

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

Could any navy then have done better? Good question.
Click to expand...

No is the simple reply.

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

Appreciate your comments. My initial response too said nobody was good early on and that things got better
Certainly the RN was not below the average in AAA capability
 
The increase in AA defences during the war was considerable.
The POW when sunk had 16 x 5.25 DP guns, 44 x 2pd (5 x 8, 1 x4) and about 12 x 20mm.
Her sister ships at the end of the war had 16 x 5.25 DP, 88 x 2pd (8 x 8, 6 x 4), 8 x 40mm and up to 65 x 20mm. It wasn't just the number of guns. Each 2pd and 40mm mounting had its own RDF director

I should add that the US N Carolina BB when launched in mid 1940 had 16 x 1.1 (4 x 4) 12 HMG
 
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The addition of the HA 4in guns was really more of a morale booster, and I'm fairly certain that they would have preferred to add another quad pom-pom, but not enough were available. The real aircraft killers were the CIWS; the quad pom-pom, 20mm Oerlikon or quad .5in.

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

HMS Ledbury claimed 4 kills during Pedestal and almost certainly got 3. You can read her action report on this website:
HMS Ledbury story, Pedestal Convoy August 1942
also check out:
HMS Scylla Story, 1942 - 1943
for a detailed description of RN AA FC in action
 
I dont know that LAA is more effective or important than a good HAA weapon.

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

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

Interestingly, the US did consider the POM for general use in the USN. "Among the machine guns under consideration were the Army's 37-mm and the British Navy's 2-pounder, more commonly known as the "pompom." The decision soon narrowed to a choice between the Bofors and the British gun. The British were anxious to have their gun adopted, and the fact that British aid would be readily available in initiating manufacture was put forward as an argument in favor of its selection. The 2-pounder, moreover was giving a good account of itself on British ships. On the other hand, there was the distinct disadvantage that the gun was designed for cordite powder, and no manufacturing facilities for the production of this ammunition were available in the United States. Thorough study revealed that the gun could not be converted to take American powder. Another consideration was muzzle velocity: The pompom had a relatively low velocity, 2350 feet per second as compared with 2830 for the Bofors. The success of the pompom in action was more than offset by the proved qualities of the Bofors in the hands of a number of powers who were using it, and the Bureau decided to join that group. Shortly after the Bureau's selection of the Bofors, British naval officials also decided to adopt the gun"
 
Following the Kamikaze experience, the USN took a new look at AAA. The USN decided to scrap the 20mm, the 40mm, and adopted the 3"/50 in single and twin mounts. The weapon had a power rammer, 20 rpm ROF per tube, 85* max elev, range at 45 deg was 14,500 yds, electric mount. The 3"/50 served through the Cold War. The idea was to get them before they got close-enough to get to you. The 3" has a useful size bursting charge. So it was now possible to get the dive bombers. Alas, jet aircraft and air-launched missiles caused yet another re-look not long after the weapon entered service. Then came the cruise missiles...
 

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


It also has this neat diagram:

And you can visualize how a torpedo bomber or other low level attack could be kept under constant fire even with 40deg elevation guns. 2ndly you can see how, even with 40 deg elevation, that aircraft attacking other ships could be kept under fire, by other than the target ship, even with 40 deg elevation.
 
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The choice between the 40mm Bofors and the 2pd is one example of the UK not getting its act together. The 2pd was in production for many years with the RN starting well before the war and the eight gunned version was by far the most effective AA mount anywhere prewar. The 40mm was a more modern weapon and had been chosen by the British Army just before the war and apart from the other advantages, was lighter a very important consideration in a destroyer.
Why the UK would have argued for the 2pd over the 40mm is beyond me.
 

The quad 2pdr had an on-mount magazine capacity of 114 rounds/gun (456 rounds and 1130 rounds on the octuple) and could fire for about one minute at full rate without reloading. It had a smaller crew than a twin bofors and a much higher effective RoF. The total weight of the quad 2pdr includes the on mount ammo, where the twin bofors weights are just for the mount. The pom-pom was liquid cooled and could fire until ammo exhaustion where the initial bofors mounts were aircooled, and it took the US quite a while to engineer a liquid cooled mount; I expect that they could have mass produced the pom-pom much more quickly. The pom-pom had director control on cruisers and larger ships right from the start, where the bofors had to wait until mid 1942 for the USN to develop a director.
 
Glider said:
The 40mm was a more modern weapon and had been chosen by the British Army just before the war and apart from the other advantages, was lighter a very important consideration in a destroyer.
Click to expand...

I imagine it takes longer to introduce a weapon into naval service than it does land service though later experience showed just bolting the Army Bofors to the deck was a quick way of getting a good weapon to sea. Perhaps the RN thought better to stick with what we have rather than go for a new weapon that needs a new production line. The RN certainly knew the Pom Pom was near the end of its life and had been looking for a replacement for several years but there is a certain inertia in replacing obsolescent but still relatively new weapons, the Treasury probably asked why do you want a new automatic AA gun when we have just spent millions on the last one.
 
It was as much about ammunition supply as anything. The RN had huge stocks of 2pdr ammunition, and the set up to build the guns. It took a long time to get the Bofors into service, for both Navies.....1943 for the USN and 1944 for the RN.....and the RN was at war in 1939. it was very much a case of "making do"
 
the British made their first issue of water cooled guns in Nov 1942 to the HMS Whimbrel (commissioned on the 13 January 1943) It may have take quite a while to actually start replacing existing 2pdrs instead of just fitting to new construction.

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

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


errrrr, you may want to rephrase this.
Technically speaking, If it explodes, it has a blast radius. Maybe not where you want it
 
It was an answer to a previous post which stated :

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

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

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