Dive Bomber Comparison

Ad: This forum contains affiliate links to products on Amazon and eBay. More information in Terms and rules

Hi Nikademus

Yes my comments were in reply to your post 117. We are pretty much aligned in our positions. If we feed that back into this question of AA effectiveness, if one consideres the numbers of aircraft facing the RN, and then the generally poor levels of air cover (compared to that enjoyed in the Pacific) the reasons for the high loss rates in British warships start to make sense. Moreover, the comments about the relative lack of effectiveness of British seaborne flak need to be taken with a bit of salt. There is no doubt that British AA was weak, but in the time frame we are talking about (1940-42) there is not as much difference I think as is being attempted to be argued here. In the Excess convoys, I believe the British task force (there were actually four task forces, but only one engaged FKX), managed to shoot down 13 aircraft (based on Luftwaffe reports). Subsequently the AA defences managed to keep the Germans at bay for 10 days (????) without further serious damage to the carrier. Whether you want to measure flak effectiveness by numbers of aircraft shot down, or in terms of protecting the ship, the efforts by the RN in that operation are not too bad.

By comparison, where flk defence was not maintained, such as over PQ-17, the loss rates for unprotected ships go through the roof. If the problem is looked at from the point of view of operational results, I just dont get the argument that RN AA sucked at what it was supposed to be doing.
 
As one of the people criticising RN AAA defences, I should clarify by acknowledging that it did a job. However, in the early days it was not doing the job as well as it could have done. The installation of low angle mounts for DD main batteries was, IMHO, a mistake, one which the USN avoided in their destroyer designs. The USN clearly had a keen appreciation of the threat posed by aircraft - hardly surprising give Mitchell's experiments off Cape Hatteras. The RN, on the other hand, was still planning to fight another Jutland, evidenced by it's optimisation of armaments for surface engagement and the attitude to CVs I noted above. Had the RN followed the USN philosophy and provided more medium-calibre automatic weapons from day one, coupled with HA mounts for 4 and 4.7in guns, it might have suffered fewer losses to enemy air power in the earlier stages of the war.
 


Yup. I also note alot of attention to detail in the technical specifics of the heavy AA guns. There's no dispute that the 5/38 was a technically superior mount to the 5.25in but early-midwar wartime results were not all that disparate in the end. Even at Santa Cruz the pre-VT heavies accounted for approx only 5% of the losses. USN AA performance at the first three carrier skirmishes were not markedly superior to RN AA returns. Santa Cruz saw the first marked increase in outright AA losses and was mainly driven by the addition in substantial numbers of 20mm and 40mm Bofors.
 
Had the RN followed the USN philosophy and provided more medium-calibre automatic weapons from day one, coupled with HA mounts for 4 and 4.7in guns, it might have suffered fewer losses to enemy air power in the earlier stages of the war.
Click to expand...

It's overly harsh to compare early-war RN ships with late-war USN ones.

The choice of not having dual purpose guns on the destroyers was a fairly simple one of cost. Dual purpose guns cost more and need bigger ships which again cost more. The difference is not insignificant. The actual effectiveness of dual purpose guns before proximity fuzes was pretty much negligible. They served as little more than a distraction. 40deg elevation still gave the capability for barrage fire over mutually supporting ships, which is how they were used. The dual purpose guns in the USN were used in the same way - barrage fire, because the fire control problems at close range was too demanding.

The RN was far ahead in deployment of an effective medium calibre automatic weapon with the 2pdr. At the same time US ships were being armed with small numbers of machine guns and later 1.1" guns. It would have been nice to have more 2pdr guns, but there were production difficulties in producing enough, and then later on with the more effective 40mm Bofors.

Was RN anti-aircraft fire in the early war years poor? Yes it was, but so was everyone else's. The large deployment of the 2pdr actually made it better off than most navies. Later in the war - difficulties in producing enough 2pdrs, 40mm Bofors, and the simply time to refit ships lead to her position declining.
 

The RN actually put a lot more focus on 40mm and smaller automatic weapons, than the USN, or any other navy, prior to Sept 1939, and these turned out to be the most effective AA weapons throughout WW2. Focusing exclusively on medium calibre guns is a bit of a red herring, when they were not particularly efficient at knocking down aircraft. A Tribal or JK class destroyer with a quad pom-pom and 2 quad .5in MG probably has a greater chance of destroying a DB than another destroyer with 85 deg main armament, but only 4 x .5" MG.
 
Hello RCAFson
IMHO RN didn't have any decent DP gun armed DDs early in the war save those couple Ls armed with 4 4" twin mounts instead of with the class normal 3 4.7" twin mounts and half of the Os and Ps which had 4 single 4" guns instead of 4 single 4.7" guns. Later from S Class onwards they got DDs with 55deg max elevation main armament, first with 4.7" guns and then with newer 4.5" guns. And even 55deg elevation wasn't same than 85 deg.

On AAA, quad 2pdr wasn't excellent gun, IIRC RN itself later thought that a twin Bofors was a better weapon and those quad .5 Vickers guns were rather useless. And that quad 2pdr in Tribals was badly wooded before they removed the rear/mizzen mast.

Juha
 
Last edited:
Also, as we have also discussed, direction systems for RN vessels early in the war were substandard, and it took time for them to be replaced. To respond to redadmiral, I'm actually comparing pre-war to pre-war: the USN was fitting HA mounts to the Benson-Gleaves class, which were in widespread service by Pearl Harbour, but first entered service in 1938.

I'm not debating the fact that early war, DP guns were mostly useful for barrage fire; certainly the results from pre-war HACS testing left the RN with little choice. But surely you see that a mount with 85 degree elevation can cover a greater volume of sky than onw with 40 degrees? And that means more chances to break up the enemies attack, increasing your chances of survival...
 

The RN also had about 25 Hunt class destroyers in commission by the end of 1940, and they alll had 2 or 3 twin 4" HA mounts, a quad pom-pom and 2 quad .5" or 2 x 20mm. Another 20 entered service by the end of 1941. A number of WW1 destroyers were also refitted with twin 4" HA guns. to provide coastal escort.

The Bofors was a better gun overall than the Pom-pom, but only the Dutch navy had them in service in 1939, followed by the RN in 1941, albeit in limited numbers. The USN didn't get them in quantity until late 1942. If a quad .5" is useless, then what does that say about single .5" guns? However, I for one, would not want to fly close to a ship that is firing at me with 4 .5" MGs, at a combined rate of 50 rounds per second. The quad pom-pom also had something like a 100 round magazine capacity and could fire for about a minute without reloading, where the bofors must be constantly fed ammo.

Again, we are focusing on RN versus USN, when clearly the RN was far ahead of the Axis navies in AA.
 

The prewar USN Mk33 FC system was not very good, by all accounts, and the Mk37 which was better. really didn't enter service till 1941. The Tribal class had an AA FC system, and they began to enter service in 1938.

In fact prewar HACS testing was quite encouraging, and maybe gave the RN false confidence, after all they did shoot down 6 target drones in one month, in 1936. As for sky coverage it all depends, because if you have, say 10 destroyers around a carrier, for example, and an attack come in against the carrier, most of the destroyers ( except for the ones directly overflown) will be able to continuously engage the targets until they attack, as a destroyer screen was typically 5-6000 yards away from the centre ship. As mentioned previously. LA guns are lighter, so a destroyer can carry more of them, and after 1938 all RN destroyers had a quad pom-pom for close range defence.

Again. no German or Italian destroyers had any DP guns.
 
Hello RCAFson
Yes Hunt had long-range AA capacity, but not even RN counted them as Fleet destroyers, they were too slow for fleet work and the early marks lacked torpedoes. But you are right and I should have use definition Fleet destroyers. And I made another mistake, there were four 4" Ls and Ls and Ms 4.7" mountings had max 50deg elevation, even if they were not well suited for AA work.

on .5", US .5 was much better weapon than RN .5 Vickers, not saing that US .5 was adequate for AA work in 40s but it was clearly better than its British cousin.

Pom-pom was rather prone to stoppages, IIRC mainly because of the belts not because of the gun itself, and even if Bofors was loaded by 4 or 5 rounds clips it could fire continuously if loaders did their job. Early in the war KM was handicapped by the fact that its 37mm was semi-automatic but on the other hand its muzzle velocity was clearly higher than that of Pom-pom and its mounting was stabilized on all tree axles. IMHO quadruple pom-pom was better weapon than KM's twin 37mm, but latter also had its pros. And IMHO KM's 20mm was better than RN's quad .5. And the point was that early in the war RN DDs needed much more AA than KM's DDs. Late in the war, especially those KM DDs which had got Barbara-upgrade had fairly powerful AAA, much more powerful than that of contemporary RN DDs and almost as good as contemporary USN DDs

And lastly, I'm wondering why, while accepting navweaps.comin critics on the AA capabilities of US and IJN 5" guns you seemed to ignore totally their opinion on RN 4.7" , namely "The lack of a DP function for these weapons was keenly felt throughout the war as more British destroyers were sunk by air attack than from any other cause. What little AA capability that these weapons did have was hindered by a lack of a tachymetric (predictive) fire control system and the setting of HE time fuzes by hand. " Britain 4.7"/45 (12 cm) QF Mark IX

Juha
 
Last edited:
Juha said:
Hello RCAFson


Juha
Click to expand...

The RN often used heavy units of the fleet to escort convoys, and during these operations the Hunts could act as "fleet" destroyers. The RN also had a number of older battleships, that were slow enough for the Hunts to act as escorts.

The RN .5" quad did have a larger ammo capacity than the USN .5" ( 200 rounds per gun versus about 100 ) which would increase its effective rate of fire, but the BMG was a pretty good gun.

The RN introduced their version of the Dutch Hazemeyer mount in 1942. It featured twin 40mm bofors, triaxial stabilization, tachymetric fire control and type 282 radar. It was probably the most sophisticated mount used in WW2, but it was also said to be unreliable, so I wonder if it was really better than the old pom-pom?

The pom-pom had a mixed record on stoppages and some guns were nearly flawless, but it does seem to vary. Here's the pom-pom and 4.5in guns in action. Watch the shell bursts chase the Luftwaffe bomber
CONVOY TO RUSSIA - British Pathe
but as you can see, the 4.5" guns are not being fired at high elevation. Obviously, if these were 4.7" guns the rate of fire and effectiveness would be nearly identical.

I don't ignore navweaps opinion on the 4.7" but I don't agree with some of what they say because a 40 deg elevation DP gun will be able to engage a wide variety of aerial targets, and if the RN fire control wasn't perfect, it was certainly better than nothing, and they did use it to shoot down aircraft. It also gained radar before everyone else. Regarding the fuse setting wikipedia states:
but all CP Mk XIX mountings were equipped with Fuze Setting Pedestals or Mk V Fuze Setting Trays...(3)
(3) Hodges and Friedman, Destroyer weapons of WW2, P95-96.
4.7 inch QF Mark XII - Wikipedia, the free encyclopedia
 
My two cents worth on some of the technical discussions occurring…..

i) HACs

Campbell is of the opinion that British HACs was better than barrage fire, but was still not as good as it should have been. Whilst the technical specs are a bit confusing to me, it seems it worked okay against aircraft flying straight, level and not too fast, but became progressively less as other variables were introduced. I think as a general statement US director control was superior, even the earlier pre-war models


ii) the 5/38 was a better AA weapon than the 4.7, and in fact not all the mounts for the 4.7 could be claimed as even remotely DP. In many ways the 4.7 "DP" was similar in performance to the Japanese 5" "DP". The AA ability of both was limited.

However the superior AA performance of the 5/38 came at a rather severe penalty in range and perf0ormance when operating in the surface role. Given that a surprising number of surface engagements occurred, I am not so sure that the 5/38 did in fact represent the best compromise. Its strong points were its high rate of fire, quick traverse, and high elevation.

iii) At the beginning of the war, through to the latter half of 1942, the USN was actually mostly reliant on LAA that was less well developed than that in the RN. Their principal LAA weapon was not the Bofors, it was the 1.1" AA mount. At the beginning of the war the principal AA weapon in the RN was the 40mm Pom Pom, usually in multiple mounts. I have not heard before that it suffered large stoppages, and Campbell does not mention this in the details he provides. Some of the old timers I got to know thought it a satisfactory weapon, if a little heavy and short ranged. But it was superior in effective rate of fire to the 1.1" US gun though I don't know anyone who used this weapon.

I don't think there is any measurable difference between the Vickers and the browning 0.5" at least none likely too make too much difference. But then 0.5" HMGs were very much second string equipment, only effective at keeping attackers some distance from their targets. Similar arguments can be mounted for nearly all weapons 20mm and below. Even the Japanese 25mm AA weapon was borderline in this respect. The old timers had a saying Time to hit the deck if the 20s open up….

With the introduction of the 40mm Bofors, nearly all other LAA armament became virtually obsolete. The US was fitted with this weapon well before the British and on a more lavish scale, so in that period 1943-1945 the USN held the advantage, in no small measure due to the lavish allocation of the Bofors to fleet defence. Once the RN started to receive the Bofors in substantial numbers (ie from '45) the differences between the two navies effectiveness wise narrowed to virtually nothing.

Iv) Individually British light ships were les well equipped , but in the category of light forces (DDs and below) were far greater in numbers than in the USN, at least until the latter part of 1942, when the balance shifted in favour of the USN. US DDs tended to be larger and as a consequence were better equipped but there were less of them (until the end of '42).

Britain did develop reasonably efficient AA guns. The one most easily referred to is the 4.5". This was a true DP gun, and having worked it myself, there were no obvious faults or drawbacks (admittedly when I trained on it in the '70s, it was obsolete, because it lacked an auto loader in the mounts we were using). This gun was fitted to a large proportion of the later war DDs. The Brits also built the LM class destroyers, which I believe had 4.5 in main armament.

v) Both navies found their arrangements for AA inadequate to fully deal with Kamikazes. The ad hoc counter to this was to beef up the AA defences on ships, particularly the 40mm Bofors numbers. This helped to curtail, but did not completely solve the threat posed by the Japanese Kamikazes.
 
Last edited:
Hello RCAFson
On Hazemeyer, yes probably the most advanced and sophisticated AAA mount but rather heavy for its firepower and as you say, maintenance intensive, and often "sick". IMHO US simple 40mm Bofors twin mount was a better option. Just like of RN postwar Bofors mountings the Mk 5 lived longer even if the STAAG mount was theoretically clearly better.

On the film had seen it before, and as it was shot during action against torpedoplanes of KG 26, its not surprising that firing angles were rather low. Even KM and Soviet Navy DDs could use their main armaments, 5" and 5.1" respectively, against torpedo planes.

On fuze setting, not bothering to look Wiki checked from my copy of Hodges and Friedman, according to it the Fuze-setting Machine Mk V was manual.

Of course RN AA arrangements were better than nothing but IMHO not very good, led down especially by the early HACS, which was after all the core of its long range AA defence, and quad .5". Quad pom-pom wasn't bad weapon but not excellent either. And its location on Tribals was rather bad, not being able to shoot to rear sectors and same time being somewhat wooded by the bridge, stacks and foremast in front sectors.

Hello Parsifal
I agree with your analyze on HACS if you are talking on early versions.

Yes, RN 4.7" was optimized for surface use and IMHO 5"/38 was a better compromise for DD main armament. One reason for this was that RN had to halve the torpedo armament of its DDs to get even one proper HA gun onboard and torpedo was seen as a very important element of DD armament on those days.

On .5"s, not bothering check the specks but IMHO the difference was shown in the fact that when RAF found .303 mg inadequate, it never seriously thought adopting .5 Vickers but immediately after Browning .5 became available to it Spitfire wing was adapted to take one, the E Wing., and it began to install gun turrets with twin .5" Brownings.

If there was no big difference between .5" and 20mm why RN rushed to install 20mm guns in place of Quad .5" when 20mm became available? IMHO 20mm was a step forward but as planes came bigger and stronger also its usefulness diminished. As did that of 40mm, USN was moving to 3" when war ended.

Ls and Ms had 4.7" L/50 guns with 50deg max elevation fully covered mounts, one S had 4.5" fore guns as a test ship but first class to have 4.5" was the Z IIRC. Before that 4.52 was reserved to reconstructed BBs and to Renown and especially for carriers, which had 4.5" heavy AA from Ark Royal onwards, 8 twin mounts per ship. Army also used 4.5" AA guns.

And IIRC none of RN DDs had an AA armament of 5-6 real DP guns and 12-16 40mm Bofors plus many 20mm.as late war USN DDs had. But as you wrote many RN DDs were smaller ships that because desperate need for convoy escorts combined with run down capacity because of the Great Depression forced it to accept quantity over quality during early war years, when war ended, Battles and Darings were in pipeline and they had DP main armament backed up with numerous Boforses.

Juha
 
Hello RCAFson
On Hazemeyer, yes probably the most advanced and sophisticated AAA mount but rather heavy for its firepower and as you say, maintenance intensive, and so often "sick". IMHO US simple 40mm Bofors twin mount was a better option. Just like of RN postwar Bofors mountings the Mk 5 lived longer even if the STAAG mount was theoretically clearly better.

On the film had seen it before, and as it was shot during action against torpedoplanes of KG 26, its not surprising that firing angles were rather low. Even KM and Soviet Navy DDs could use their main armaments, 5" and 5.1" respectively, against torpedo planes.

On fuze setting, not bothering to look Wiki checked from my copy of Hodges and Friedman, according to it the Fuze-setting Machine Mk V was manual.

Of course RN AA arrangements were better than nothing but IMHO not very good, let down especially by the early HACS, which was after all the core of its long range AA defence, and quad .5". Quad pom-pom wasn't bad weapon but not excellent either. And its location on Tribals was rather bad, not being able to shoot to rear sectors and same time being somewhat wooded by the bridge, stacks and foremast in front sectors.

Hello Parsifal
I agree with your analyze on HACS if you are talking on early versions.

Yes, RN 4.7" was optimized for surface use and IMHO 5"/38 was a better compromise for DD main armament. One reason for this was that RN had to halve the torpedo armament of its DDs to get even one proper HA gun onboard and torpedo was seen as a very important element of DD armament on those days.

On .5"s, not bothering check the specks but IMHO the difference was shown in the fact that when RAF found .303 mg inadequate, it never seriously thought adopting .5 Vickers but immediately after Browning .5 became available to it Spitfire wing was adapted to take one, the E Wing., and it began to install gun turrets with twin .5" Brownings.

If there was no big difference between .5" and 20mm why RN rushed to install 20mm guns in place of Quad .5" when 20mm became available? IMHO 20mm was a step forward but as planes came bigger and stronger also its usefulness diminished. As did that of 40mm, USN was moving to 3" when war ended.

Ls and Ms had 4.7" L/50 guns with 50deg max elevation fully covered mounts, one S had 4.5" fore guns as a test ship but first class to have 4.5" was the Z IIRC. Before that 4.5" was reserved to reconstructed BBs and to Renown and especially for carriers, which had 4.5" heavy AA from Ark Royal onwards, 8 twin mounts per ship. Army also used 4.5" AA guns.

And IIRC none of RN DDs had an AA armament of 5-6 real DP guns and 12-16 40mm Bofors plus many 20mm as late war USN DDs had. But as you wrote many RN DDs were smaller ships, that because desperate need for convoy escorts combined with run down capacity because of the Great Depression forced it to accept quantity over quality during the early war years, when war ended, Battles and Darings were in pipeline and they had DP main armament backed up with numerous Boforses.

Juha
 
Last edited:
A few words on the pom-pom;

While a powerful weapon, the RN realised early on that the massive smoke and vibration associated with 8 large weapons firing made optical aiming virtually impossible. The Pom-Pom Director was introduced in the late 30's, providing simple, non-tachymetric 'follow-the-pointer' direction to the layer and trainer on the mount.

In 1940 it was superceded by the MkIV director, which included a GRU for tachymetric direction. However, it was not stabilised against the ship and therefore required a highly skilled crew to realise it's potential.

HMS Prince of Wales went to her doom carrying the ultimate version of MkIV, equipped with RPC and linked to Type 282 radar. However, the size and weight of such installations meant that most DDs did NOT carry a Director at all, and relied on the crew aiming from a rolling, pitching, yawing and vibrating platform, through a cloud of their own smoke, right until the end of the war. I think that must be the definition of a weapon system getting in it's own way...
 

AFAIK, the USN Mk 14 gyro sight and Mk51 director for the 40mm quad, was not stabilized either. The RN began to fit small directors on destroyers, but not until late in the war. Even with eye shooting the quad pom-pom would still have put a lot of shells into the air, and all axis destroyers relied on eyeshooting for their close range weapons.
 

For a destroyer to engage aircraft, it has to have a FC system that can predict the aircraft movement and send the correct fuse timing to the guns, and KM and Italian destroyers could not do this.

Here's a fuse setter from HMCS Haida:
http://hmcshaida.ca/4ingun_interior.jpg
HMCS HAIDA - Tour Stop 1

the fuze setter is connected to the FC computer which sends the fuse timing continuoisly until the load lamp lights and the shell is placed into the breech of the gun:
The Gunnery Pocket Book - Part 4

Regarding the .5" Vickers, by late war the BMG was in mass production but the Vickers was quite a bit lighter than the BMG and would have been a better gun than the .303 BMG, IMHO.

The 4.7in twin was a "real" DP gun, but it was limited to 40 deg elevation. If you read accounts of Coral Sea and Midway actions, you will see that 4.7in twin armed destroyers could have engage the attacking aircraft throughout their attacks, either by directly engaging the attacking aircraft or by placing a barrage over the carriers.
 

Putting a lot of shells in the air isn't particularly useful when they're not aimed. I think there is an opinion developing in this thread that RN AA must have been OK because it was better than the Axis equivalent. That is fair enough, but I still contend that it could have been better had more time and money been spent on it. It is clear from my reading though, that the RN did not take air attack seriously enough before the war, and paid a heavy price for this attitude once hostilities commenced. Phillips would not have taken Force Z into an area of Japanese air superiority with no carriers and limited AAA defence if he had had a serious appreciation of Japanese airpower and the threat it posed to capital ships...
 

Using eyesights is not as good as a director, but they are still aimed. AFAIK, USN destroyers didn't begin to get 40mm guns and directors until sometime in 1943, so they weren't that far ahead.

The RN equipped their ships with the best AA weapons available before the war, and they certainly did not give up anything to the USN, in 1939 except in terms of DP weapons for destroyers, and even there they weren't that far behind.

Warspite 1939:
4 x twin 4"
4 x octuple pom-pom
4 x quad .5"

R class Battleships 1939
4 x twin 4"
2 x octuple pom-pom
2 x quad .5"

Colarado 1939
8 x 5" singles
4 - 8 x .5 MGs (hard to find exact info)

Ark Royal 1939
8 x 4.5" twin
4 x octuple pom-pom
8 x quad .5"

Enterprise 1939
8 × single 5 in/38 cal guns
4 × quad 1.1 in/75 cal guns
24 × .50 caliber machine guns

HMS Southhampton
8 × QF 4 in (100 mm) Mark XVI guns (4x2)
8 × QF 2-pounder (40 mm) Mark VIII pom-pom guns (2x4)
8 × .5 in (13 mm) Vickers machine guns (2x4)

USS Brooklyn 1939
8 × 5 inch/38 caliber guns (8x1)
8 × .50 caliber machine guns (8x1)

In 1939 the RN was ahead in terms of AA in every ship class, except, maybe destroyers.

From what I gather, Philips didn't realize the IJN had long range TBs.
 
You've talked straight past my point again. I'm fully aware of the armaments of various USN and RN classes. I'm also aware that the USN didn't fit the 'magic' Bofors until later in the war. My assertion, about fifty posts back, was that the RN used sub-standard equipment early in the war, partly out of cost-saving, partly out of an under-appreciation of the threat posed by air attack. I'm not arguing it was better or worse than anybody else's equipment, just that it wasn't as good as it could have been and that this failure cost the RN dearly throughout the early phases of the war

I'm going to make this my last post in this thread, as it seems you will continue to claim that the RN had good AAA as it was no worse than anyone elses's...
 
You must log in or register to reply here.

Users who are viewing this thread

Total: 1 (members: 0, guests: 1)

Similar threads

S
WW2 aero engine fuel consumption comparison
Replies
19
Views
2K
ThomasP
T
S
Comparison of the Gloster F.5/34 and the Mitsubishi A6M2.
3 4 5
Replies
86
Views
5K
z42
Z
XB-24J prototype bomber
Replies
18
Views
1K
GrauGeist
Whenever I come across a comparison featuring the Zero alongside more advanced aircraft...
Replies
1
Views
855
yulzari
R
SBD dive bombing procedures
2 3
Replies
52
Views
6K
Retattack
R
Menu
Log in
Register