Destroyers.....

[RCAFson]

To bring some reality back into the discusion:

SECRET

CYPHER MESSAGE

CONFIDENTIAL Received S.1 (Tele. 1735 hours – 8/5/40

To: C.in C. Mediterrean 927. C.in C. East Indies 900
C.in C. China 849. C.in C. South Atlantic 933
C.in C. America and West Indies 668. F.O.C. North Atlantic 716
R.A. South America Division 508. F.O. Narvik, R.A. 3 601.
C.in C. Portsmouth 569. C.in C. Nore 971. C.in C. Western Approaches 51.
C.in C. Rosyth 808. V.A. Dover 723. A.C.O.S. 147
N.O. Melbourne 767. N.O. Wellington 361. N.S. H.Q. Ottawa 950

Repeated C.in C. Home Fleet 769.

From: Admiralty

The following is a summary of the experience so far as it can at present be ascertained, against aircraft during three weeks off the Norwegian coast. Technical improvements are in hand, but there is wide recognition of the imperative need to make the best use of the experience of those who had had to conduct operations and meet strong and persistent air attacks, for it is only by this means that our present equipment can be used to the best advantage.

2. It has been necessary to operate ships within easy reach of enemy shore based aircraft working from Stavanger, Oslo, and from Danish aerodromes. Ships have been constantly bombed at sea, also when approaching the Trondheim area with convoys and whilst in the fiords where anti aircraft ships, destroyers and sloops have had to remain for A/A protection of the bases. No base could be established for operating own shore based aircraft in support.

3. It is difficult yet to estimate the scale of attack but it appears that between 9th April and 3rd May well over 1400 shots were made at ships, many of which were sticks of bombs. It is estimated by the Air Ministry that the enemy used 470 Long Range Bombers and 40 Dive Bombers of which approximately 300 long range bombers and all the Dive bombers were used against the Fleet, convoys and ships in the fiords. The initial landings in the Trondheim area were affected without interference from the air and it has to be recalled that enemy did not usually fly over the areas concerned before 0500 or after 2100, apparently because the aerodromes available were unsuitable for night flying.

4. As a result of this air effort the Allied suffered the following casualties:

(a). Sunk, four destroyers and one sloop, of which two destroyers were sunk whilst escorting convoys returning from the evacuation. One of the destroyers was sunk at Narvik. Ten trawlers were also lost, nearly all beached as a result of near misses.

(b). Damaged, two cruisers, three destroyers, two sloops, nearly all in inshore operations.

(c). There has been minor damage to RODNEY by a direct hit and to other ships by near misses.

(d). The F.A.A. lost about 18 aircraft, but fortunately many of the crews are accounted for.

(e). No transports were appreciably damaged at sea or in the Norwegian bases.

5. During the same period the gunfire of the Fleet destroyed at least 30 enemy aircraft at sea or near the bases whilst the F.A.A. show down at least 9 aircraft and destroyed 8 on the ground.

6. Generally speaking when an A/A ship or sloop was able to cover the base the enemy flew high, concentrated on the warship and the intensity of the attack on the base was reduced. The more serious damage to the bases was done in each case when no A/A ship was present.

At sea the enemy has shown marked preference to attack ships with the weaker A.A. armament.

7. As a result of attacks on ships at sea it appears that about 75% of the hits and near misses have been from dive bombers and that about 75% of these were unfired at mainly due to surprise gained by cloud or sun or to attention being directed to other aircraft.

8. Before 3rd May when returning from the evacuation dive bombing was generally shallow and at about 35 degrees and the enemy rarely attempted to synchronize attacks, usually attacking independently using clouds and sun to screen approach. On 3rd May steep dive bombing at 65 degrees by about 30 JU 87 (b) was experienced. AFRIDI and BISON were damaged by these attacks which seem to have developed as soon as Trondheim aerodrome became available for these shorter range aircraft after damage done by the F.A.A. attacks which delayed its use during a vital period. On this day the attacks were greater in strength and consequently appeared more concerted.

9. It appears that enemy aircraft wait about overhead where they are impossible targets for destroyers and difficult for any ship. Steps are being taken to strengthen the short range armament of destroyers who have to operate within the range of dive bombers. It is to be recalled however that except for special aircraft for steep dive bombing and level bombing from considerable heights enemy aircraft must come within the envelope of a 40 degree gun when approaching for an attack.

10. In High Level attacks enemy generally turn away when fired at and may repeat this procedure 10 or 20 times, apparently hoping to gain an unfired at approach. This results in great expenditure of A/A ammunition an the only answer is to place the first salvo so close to him that he dare not repeat the procedure. Experience indicates that if this result can be obtained the enemy takes an early chance to complete his bombing run, or unloads his bombers harmlessly at once, or sheers off to attack a less menacing target. There is general agreement that our material and training can produce such a result, and that it can only be ensured by frequently testing height finders and practicing control personnel against aircraft; careful attention to the ballistic adjustment for wear of guns and other factors being also essential. Accuracy of fire has often been greatly improved by occasional flank marking reports.

11. A four cornered ship like VALIANT, RENOWN, or ARK ROYAL is particularly disliked because of her ability to watch simultaneously the more dangerous directions of approach and the consequent rapidity with which the enemy can be engaged by weapons whose shell burst he can see.

12. Against Dive Bombers, it is essential, with our present equipment, to fire immediately even if only with approximate accuracy, because the enemy is inclined to pull out early and thus reduce his accuracy. When cloud and sun conditions favour dive bombing it is therefore of first importance, that in addition to using short range weapons to the best advantage all ships should try to emulate the four cornered ship and develop the ability to fire rounds bursting ahead of the enemy within, say 5 degrees or 10 degrees, immediately he appears in the dive. Enemy aircraft except the JU 87 (b) have generally tried to attack within about 30 degrees of the fore and aft line in a dive of about 30 degrees.

The above remarks also apply to low level bombing (2 to 3000 feet) in conditions where surprise can be effected.

13. Experience confirms that where practicable the course and speed should be shaped to favour development of gunfire and so that the related wind is high and if possible across the probable direction of the dive. It follows that if a ship is stopped she is a more favourable target for dive bombers.

14. It is a frequent experience that on the first occasion of being bombed, particularly if a heavy attack, excitement causes a loss of accuracy, reduction of fire discipline and wastage of ammunition. If this likely result is widely known its effect may well be reduced.

15. Although some attacks have been well pressed home this has not so far been the case generally, neither have they usually been synchronized. To prevent such development by the enemy particular attention is necessary to the points referred to in paragraphs 10 to 14.

16. R/DF which has already given valuable warning at sea should go far to militate against surprise when fitted generally, and other developments should contribute much to effective long and short range A/A fire. Meanwhile it has to be recalled that on the Norwegian coast ships have been working at great disadvantage, in most arduous conditions where fatigue has been a serious factor and after a period when it has been particularly difficult to afford facilities for practices.

Copies to:
C.A.S.
V.C.A.S.
D.C.A.S.
A.C.A.S. (G)
A.C.O.
D. of Plans
D.H.O.
D.N.O.
D.D. Plans Ops
D.M.C.
D.D.W.O.
F.O. 6 Sigs 1.a.(S/L Weston)
F.O. 7 (Action) A.I.1 (W)
F.O. 2.b (3)

Again, if we place USN destroyers into the same situation - will they do better? We know that they have HA main armament, but we also know that the Mk 33 is a very slow and clumsy FC system, that was generally hopeless against surprise attack, and we know that USN destroyers have a much lighter CIWS than RN Tribal-JKMN destroyers. It is also apparent that the RN was subjected to a scale of attack unlike anything seen in the Pacific in 1942.

 

[RCAFson]

Some comments on USN RPC (automatic gun drives):

Crenshaw of USS Maury:

Our training schedule took on more importance and the tempo picked up. As Assistant Gunnery Officer, I attended the Gunnery Officer's School held on Dixie once a week and heard the Squadron Gunnery Officers expound on the arcane art. One could read all about the technical details of our guns and fire control in the manuals, but hearing how to handle the equipment from the best in the fleet brought it all to reality. Automatic Gun Drives were still new in the Fleet and were plagued with reliability problems. The intricacies of the Mk-10 Rangekeeper were baffling to most officers. I found it all fascinating and listened with relish.

So in the Spring of 1941 USN RPC was still unreliable - I wonder what it was like in April 1940?

Here's some more that backs up Crenshaw:

Mindell, David A.. Between Human and Machine : Feedback, Control, and Computing before Cybernetics:

"...The director and the computer formed what one user manual called a "regenerative group," a feedback loop that eased the job of tracking fast-moving targets. 111 However useful and innovative, this feature exceeded the limits of BuOrd's or its contractors' technical knowledge. The feedback loop on the Mark 37,"a previously untried closed-circuit servo," had a stability problem: the output of the computer moved the director, which in turn affected the input to the computer. Both the computer and the power drives had time lags, so the two could push and pull each other and make the system oscillate. How these loops interacted and fed back on each other was poorly understood and caused severe problems in operations. (112) When radar was added in 1940,the noisy, often erratic signals instigated a complete breakdown. But the equipment was already in production, and the navy was preparing for war. The stability problem in the Mark 37 was the most prominent example of a complication arising throughout naval fire control. Wherever sensitive instruments and intricate computers drove powerful servos on heavy gun mounts the systems could become unstable."It is well known," a 1937 report read, that "the guns, because of their enormous inertia, do not respond instantaneously to a signal from the director...for similar reasons the guns tend to swing too far when coming to alignment with the director after such motion, giving rise to 'hunting' or oscillations." (113) Adjustments could make these systems stable, but only at the cost of unacceptably degraded performance. A series of tests identified an "inherent weakness"in the Ford system of control and in the hydraulic speed gear with which it was used. BuOrd's precious machines suffered from "insufficient 'stiffness' or 'rigidity' or a lack of prompt response to the director system." (114) Naval fire control systems, for all their precision, ruggedness, and sophistication, had run up against a problem the engineering culture could not solve: how to make a feedback loop move a large mass at high speed without making it unstable. Naval fire control systems, for all their precision, ruggedness, and sophistication, had run up against a problem the engineering culture could not solve: how to make a feedback loop move a large mass at high speed without making it unstable..." p65-66

"...While radar easily transformed the comparatively slow (and mature) main-battery fire control, antiaircraft exposed the technology's limits, requiring much higher performance and speed. The first American fire control radars, dubbed FC and FD (later Mark 3 and 4) they were mounted atop the Mark 37 director, the most common antiaircraft system in the fleet and came off of the production line at Western Electric in June 1941. The combination was first tested aboard the USS Roe in September 1941 before an audience of navy brass and scientists, including Rivero and the NDRC's Poitras and Caldwell, but the results were less than spectacular. "The firing was entirely wild," Caldwell recalled. (10) Their troubles notwithstanding, these devices, "the guinea pigs of fire control radar," went into production, began delivery in October 1941,and served the navy through much of the war. Many hundreds were installed, and nearly every ship in the fleet of destroyer size or larger had at least one Western Electric set. They played a part in nearly every American naval action of World War II. (11) As in the army, these early navy systems were separate units not originally designed to work together, and prewar directors were ill suited to radar. The Mark 37 gunfire control system still used the Ford Mark 1 computer, an adaptation of the original Ford Rangekeeper. It was slow to converge on a solution, assumed that its target was flying straight, and had the old problem of increasing errors with decreasing range. The Mark 37's director also suffered from cramped space and restricted vision for the crew. Line officers reported that the Mark 37 worked adequately well, but only because late in the war the proximity fuze provided "a shot in the arm to the basic system that enabled it to stagger through the war, partially concealing its inherent weakness." In general, the navy expressed great dissatisfaction with the existing fire control directors. Even the small, decentralized systems, like the Sperry Mark 14 appeared successful only because of the failings of the devices they replaced. The navy wanted integrated systems of the "ultimate" type. (12)
Antiaircraft fire control radar also had problems and proved "a stepchild slow to win affection." During the war, BuOrd spawned 27 different designs for Antiaircraft fire control radar . Only 10 of these entered production, 7 actually saw action, and 3 became widely available. Yet none of these were microwave, 3 cm systems. (13) They had problems with reliability, maintenance, target discrimination, and especially automatic tracking. Jitter and noise in the radar echoes, such as glint and reflections from the plane's propeller, adversely affected the tracking servos. Only intensive human mediation- the old human servomechanisms- could produce high-quality electronic inputs for rangekeepers. Operators needed to pip match to eliminate noise, and they needed to manually follow targets with the antenna, much as they did with traditional optical rangefinders and telescopes..."p263-64

and another:

The Naval Institute guide to world naval weapons systems, 1997-1998, Friedman, p59:

MK 1 Electromechnical analog computer of the MK37 GFCS (FCS)...MK1 introduced fully automatic rate control to US practice and the MK 37 FCS was the first USN ordnance application of close-loop servo practice (initially experiencing severe problems because its feedback made it unstable) Most US ships used the MK1A version.

{Mk1A was postwar}

Please tell me why these criticisms don't show up on the Navweaps site? Why does it always praise USN systems and criticize RN systems?

Here's some more that comment on the the slowness of the USN Mk 37 FC system:

200,000 Miles aboard the Destroyer Cotten
June 1944:

Finally, a new fire control feature had been added that permitted individual 5inch mounts to be controlled by the closest 40-mm directors. This would allow Sky I to take severalattacking kamikazes under fire at the same time with a 40-mm mount and a 5inch mount, both under the same 40-mm director. It was now inescapably apparent that the main battery director and fire control computer of the typical destroyer were ineffective against diving kamikazes. The director was too slow to track a rapidly moving aircraft, and the computer was too slow to develop an accurate solution whenever changes in elevation, deflection, and range were initially rapid.

U. S. NAVY BUREAU OF ORDNANCE
IN WORLD WAR II by Rowland and Boyd.

The development of the Gun Directors Mark 33 and 37 provided
the United States Fleet with good long range fire control
against attacking planes. But while that had seemed the most
pressing problem at the time the equipments were placed under
development, it was but one part of the total problem of air defense.
At close-in ranges the accuracy of the directors fell off
sharply; even at intermediate ranges they left much to be desired.
The weight and size of the equipments militated against rapid
movement, making them difficult to shift from one target to another.
Their efficiency was thus in inverse proportion to the
proximity of danger. They lessened the danger of horizontal
bombing attacks, but placed too great a premium on early target
acquisition and rapid target designation.

and I've already mentioned this one:

"Although superior to older equipment, the computing mechanisms within the range keeper (Mk10) were too slow, both in reaching initial solutions on first picking up a target and in accommodating frequent changes in solution caused by target maneuvers. The Mk 33 was thus distinctly inadequate, as indicated to some observers in simulated air attack exercises prior to hostilities. However, final recognition of the seriousness of the deficiency and initiation of replacement plans were delayed by the below decks space difficulty, mentioned in connection with the Mk28 replacement. Furthermore, priorities of replacements of older and less effective director systems in the crowded wartime production program were responsible for the fact the Mk 33's service was lengthened to the cessation of hostilities."

{my comment regarding Mk 1A}

 

[Glider]

Very interesting stuff RCAF, many thanks

 

[RCAFson]

Very interesting stuff RCAF, many thanks

This is a very interesting account of AA fire by the light crusier HMS Scylla:
HMS Scylla Story, 1942 - 1943
Note that it claims 16RPM for her 4.5in guns.
Here's Scylla defending PQ18:
CONVOY TO RUSSIA - British Pathé
you can actually watch and time her 4.5in salvos at 5sec intervals. I wouldn't want to fly close to the pom-pom either.

 

[fastmongrel]

Please tell me why these criticisms don't show up on the Navweaps site? Why does it always praise USN systems and criticize RN systems?

Reading some sources you get the impression the RN was so incompetent they should have stayed at anchor. Funny how they seem to have managed to do so well with such archaic equipment.

 

[RCAFson]

Reading some sources you get the impression the RN was so incompetent they should have stayed at anchor. Funny how they seem to have managed to do so well with such archaic equipment.

Exactly. Considering the scale of attack faced by the RN in Norway, Dunkirk and for 3 years in the Med, the RN would have been wiped out several times over if RN AA was a bad as Navweaps would have us believe. Yet the people who knew best, the Luftwaffe and IAF, seemed to have a very healthy respect for RN AA.

 

[vinnye]

Yes they got a bit of practice didn't they! Some of the situations they worked in were suicidal!
Given the advantages in weight and when they were designed, would it not be a fairer comparison to use the Manxman Class to the USN Fletcher?

 

[cherry blossom]

It may be more important to have good ranges than a perfect predictor (off topic, the Germans had better range finders and a less sophisticated director system at Jutland). RN AA probably improved greatly over 1941 as radar started to give accurate ranges. I suspect that USN AA showed a similar improvement approximately a year later.

The British also had an automatic 40 mm AA gun Britain 2-pdr [4 cm/39 (1.575")] Mark VIII afloat in fair numbers in 1939. Even the high velocity version only managed 2,300 fps (701 mps) compared to 2,720 fps (829 mps) for the Bofor, which would have been much better, but only the Dutch, Swedish and Norwegian Navies had decided to buy the Bofor. However, the German 37 mm was not automatic in 1939 and France had only equipped one ship with an automatic 37 mm in 1940 France 37 mm/70 (1.46") Model 1935.

 

[fastmongrel]

Thats a lot of ammo, 140 rounds per barrel.

 

[parsifal]

Why would navweaps and Campbell state max rates for RN guns and practical rates for USN guns - that makes no sense at all! Yet you want to hold Navweaps up as gospel. I am willing to agree with their data but not their editorial comments which are not based upon any scientific basis, except simple hearsay.

Incorrect on two counts

My problem was that in one of your earlier posts you calcuclated the weight of fire on the basis of a rate of fire below the minimum max rof for the 5/38, and at the max rof for the 4.7 mount. It looked as if you were calculating the oputput on the practical rof for the US gun and the max rof for the Brit gun.

Second error is your claim about Navweapons basing their assesment on Hearsay. Wrong. There are some operational results and losses given, and a very solid technical overview of both guns. They provide a pretty good analysis actually, and then draw logical, inbiased (the author is neither American or British I understand) conslusions from that.

The Benson class had Mk 37 and integral hoists, but the 1939 and earlier classes did not, but these were the last USN destroyers built to treaty limits, whereas the UK, because of wartime pressures, had to continue building destroyers with treaty based hulls until the Battle class of 1945

The Z classes onward had similar hull forms to the Battles, so it was from 1942 that the RN started to change its destroyer construction program not 1945. in other words, just behind the USN, but not by much. Bensons incidentally were close to treaty limits, it was from the Fletchers onward that significant departures really began, and they were 1941 designs....

The RN entered the war with it's pre-war main armament and CIWS; what would have happened if the USN did the same? How would USN destroyers have fared in Norway or at Dunkirk

We will never know, but statisitically they should shoot down more enemy, provide better area defence and suffer a lower loss rate, if we are to believe most sources.

The problem is that instead of thinking for yourself, you seem to want to simply repeat Navweaps editorial comments - this makes for a pretty poor discussion, when as, I've stated, repeatedly, that I don't agree with their editorial comments. And you also dispute Navweaps data by asking us to pretend that RN RoFs were only half of what they state.

Im thinking for myself, but I do not misuse or misrepresent the material that is available to achiegve a wanted outcome. If I were to try to get fancy with this, you and others could justificably be baying for blood because what i was stating was just my opinion. Which is exactly what you are doing with this practical rof stuff. i certainly am not disagreeing with Navweapons. They rely on max rofs, which is fine, but if you are going to use figures that are below the max rof for one type, you need to do the same for the other....not pick the highest in the range for one type, and the lowest, or below the range for the other. Thats whats at the heart of this dispiute....colouring the lily with regard to the RN DDs whilst hammering the US type for any litle detail. That makes us no better than the LW Ra Ra boys if we start donig that.....


Moving onto your next envelope, which includes a very si zable (and generally good account of Aa in Norway. Thereas a lot in the material, and i commend you for the contribution, but this does, if anything underline the weaknesses of the 4.7 as an AA mount.

Though I could critique a lot of the material, it all leads back to the inability of the 4.7 to hit high level targets, and fails to realize that in early 1940, the Germans did not have an effective aerial torpedo. Relevantly it states

The above remarks also apply to low level bombing (2 to 3000 feet) in conditions where surprise can be effected.

Problem is, most LW attacks by their level and divebombers adopted an approach altitude considerably higher than that, typically in the region of 5-6000m. At that height, the 4.7 with 40 deg elevation can only engage a target approaching at 6000m. for a few seconds, and not effectively. The gun has a maximum horizontal range of about 17000 yads, which gives it a max vertical range of about 8000m. Again I have to enter the realm of practicality, because max ceiling is not the same as max effective ceiling. normally, the rule of thumb is that max effective ceiling for an AA gun is 20-30% less than its max ceiling. On that basis, the max effective ceiling for the 4.7 will be about 5-6000m. Anything above 7000m is out of the question. Anything above 5000m is just about impossible for it, and then only for a few seconds at extrem range. Nearly useless in other words. Which is exactly what Navweapons say. Not opinion, or editorial when you stop and think about it.

Again, if we place USN destroyers into the same situation - will they do better? We know that they have HA main armament, but we also know that the Mk 33 is a very slow and clumsy FC system, that was generally hopeless against surprise attack, and we know that USN destroyers have a much lighter CIWS than RN Tribal-JKMN destroyers. It is also apparent that the RN was subjected to a scale of attack unlike anything seen in the Pacific in 1942.

we cannot really answer that. Its not valid to say "the US did not upgraqde its CIWs until several year after the war broke out". War for the USN doid not break out until the end of 1941, before that the USN was unready for war because they were still at peace, with elements within the administration dead set against any involvement. If the USN found itself embroiled in the war from 1939, there is no reason to suggest that they would not have taken steps to upgrade their LAA defences in the opening months of their entry into war, as they did historically in 1942. We should draw similar conclusions with regard to their RPC and Director Controls. By way of comparison, the USN also had severe difficulties with the F4F a/c, but these were worked out by the time they went to war. So in response to your question, we dont know, and we cannot draw too many conclusions either. One way of looking at it is certainly to say they would, or could do noting to address the deficiencies, but another is to say they could well have addressed their deficiencies.

One thing I do take issue with hoever, is the elleged effectiveness of British CIWs. The available information is that British CIWs were pretty inneffective.....getting back to the Illustrious experience, there were 30000 rounds expended (according to Wiki) and that, along with the 3000 rounds of 4.5 in expended by the Illustrious and whatever other ammunition expended by her escort, managed to, maybe, shoot down 2 out of 40 aircraft, who in turn hit her with at least 6 bombs. Thats not good. The experiences of the PoW and Repulse are even worse.

And the claim that warfare in the Pacific was somehow easier than in Norway and in the med is highly disputable. numbers maybe, but interms of proficiency, the Japanese in 1942 were able to achieve accuracy levels of around 80% against the British (in the Indian Ocean), and pretty strike rates in other actions

 

[RCAFson]

It may be more important to have good ranges than a perfect predictor (off topic, the Germans had better range finders and a less sophisticated director system at Jutland). RN AA probably improved greatly over 1941 as radar started to give accurate ranges. I suspect that USN AA showed a similar improvement approximately a year later.

The British also had an automatic 40 mm AA gun Britain 2-pdr [4 cm/39 (1.575")] Mark VIII afloat in fair numbers in 1939. Even the high velocity version only managed 2,300 fps (701 mps) compared to 2,720 fps (829 mps) for the Bofor, which would have been much better, but only the Dutch, Swedish and Norwegian Navies had decided to buy the Bofor. However, the German 37 mm was not automatic in 1939 and France had only equipped one ship with an automatic 37 mm in 1940 France 37 mm/70 (1.46") Model 1935.

Actually, the 40mm HV pom-pom had a MV of 2400fps. I afraid you ran afoul of Navweaps dissing RN equipment again.

 

[parsifal]

Actually, the 40mm HV pom-pom had a MV of 2400fps. I afraid you ran afoul of Navweaps dissing RN equipment again.

Oh jeez here we go again, misquoting a highly reputable source for the purposes of an agenda.


The truth is the Mark VIII mount as designed had a muzzle velocity of 2300 as reported by NW. It was increased to 2400 after the introduction of a newly designed round, in 1938, which was not interchangeable (and I suspect one of the reasons behind the notorious unreliability of the 2pdr).

For the record, NW actually says this about the new round, and probably explains why they state the lower figure.....its because the lower figure MV ammunition remained in production and/or use thru-out the war concurrent to the higher velocity round. And whilst they dont say this, it may be that having two incompatible rounds for the same basic gun might explain the reliability issues that plagued the gun during the war.

For the record, the relevant quote from NW is as follows

"A higher velocity projectile was introduced in 1938 and this required a different breech mechanism and other changes to the firing gear. However, guns firing only the older low-velocity projectiles were still manufactured throughout World War II. High velocity and low velocity ammunition was not interchangeable. There were also several other gun variations, as shown in the data tables below".

NW is reporting on the older mechanism and the lower powered round, which is still valid, and not disrespecting the gun or RN equipoment.

Stop trying to put words into the mouth of such a great reference source as NW. It does your otherwise great knowledge on this subject no good at all.

 

[RCAFson]

Incorrect on two counts

a)My problem was that in one of your earlier posts you calcuclated the weight of fire on the basis of a rate of fire below the minimum max rof for the 5/38, and at the max rof for the 4.7 mount. It looked as if you were calculating the oputput on the practical rof for the US gun and the max rof for the Brit gun.

B)Second error is your claim about Navweapons basing their assesment on Hearsay. Wrong. There are some operational results and losses given, and a very solid technical overview of both guns. They provide a pretty good analysis actually, and then draw logical, inbiased (the author is neither American or British I understand) conslusions from that.




c)The Z classes onward had similar hull forms to the Battles, so it was from 1942 that the RN started to change its destroyer construction program not 1945. in other words, just behind the USN, but not by much. Bensons incidentally were close to treaty limits, it was from the Fletchers onward that significant departures really began, and they were 1941 designs....




D) We will never know, but statisitically they should shoot down more enemy, provide better area defence and suffer a lower loss rate, if we are to believe most sources.




E)Im thinking for myself, but I do not misuse or misrepresent the material that is available to achiegve a wanted outcome. If I were to try to get fancy with this, you and others could justificably be baying for blood because what i was stating was just my opinion. Which is exactly what you are doing with this practical rof stuff. i certainly am not disagreeing with Navweapons. They rely on max rofs, which is fine, but if you are going to use figures that are below the max rof for one type, you need to do the same for the other....not pick the highest in the range for one type, and the lowest, or below the range for the other. Thats whats at the heart of this dispiute....colouring the lily with regard to the RN DDs whilst hammering the US type for any litle detail. That makes us no better than the LW Ra Ra boys if we start donig that.....


f)Moving onto your next envelope, which includes a very si zable (and generally good account of Aa in Norway. Thereas a lot in the material, and i commend you for the contribution, but this does, if anything underline the weaknesses of the 4.7 as an AA mount.

g)Though I could critique a lot of the material, it all leads back to the inability of the 4.7 to hit high level targets, and fails to realize that in early 1940, the Germans did not have an effective aerial torpedo. Relevantly it states





h)Problem is, most LW attacks by their level and divebombers adopted an approach altitude considerably higher than that, typically in the region of 5-6000m. At that height, the 4.7 with 40 deg elevation can only engage a target approaching at 6000m. for a few seconds, and not effectively. The gun has a maximum horizontal range of about 17000 yads, which gives it a max vertical range of about 8000m. Again I have to enter the realm of practicality, because max ceiling is not the same as max effective ceiling. normally, the rule of thumb is that max effective ceiling for an AA gun is 20-30% less than its max ceiling. On that basis, the max effective ceiling for the 4.7 will be about 5-6000m. Anything above 7000m is out of the question. Anything above 5000m is just about impossible for it, and then only for a few seconds at extrem range. Nearly useless in other words. Which is exactly what Navweapons say. Not opinion, or editorial when you stop and think about it.




i)we cannot really answer that. Its not valid to say "the US did not upgraqde its CIWs until several year after the war broke out". War for the USN doid not break out until the end of 1941, before that the USN was unready for war because they were still at peace, with elements within the administration dead set against any involvement. If the USN found itself embroiled in the war from 1939, there is no reason to suggest that they would not have taken steps to upgrade their LAA defences in the opening months of their entry into war, as they did historically in 1942. We should draw similar conclusions with regard to their RPC and Director Controls. By way of comparison, the USN also had severe difficulties with the F4F a/c, but these were worked out by the time they went to war. So in response to your question, we dont know, and we cannot draw too many conclusions either. One way of looking at it is certainly to say they would, or could do noting to address the deficiencies, but another is to say they could well have addressed their deficiencies.

j)One thing I do take issue with hoever, is the elleged effectiveness of British CIWs. The available information is that British CIWs were pretty inneffective.....getting back to the Illustrious experience, there were 30000 rounds expended (according to Wiki) and that, along with the 3000 rounds of 4.5 in expended by the Illustrious and whatever other ammunition expended by her escort, managed to, maybe, shoot down 2 out of 40 aircraft, who in turn hit her with at least 6 bombs. Thats not good. The experiences of the PoW and Repulse are even worse.

k)And the claim that warfare in the Pacific was somehow easier than in Norway and in the med is highly disputable. numbers maybe, but interms of proficiency, the Japanese in 1942 were able to achieve accuracy levels of around 80% against the British (in the Indian Ocean), and pretty strike rates in other actions

A)I used the practical rate of fire for both weapons, and actually reduced the 4.7in to 10 rpm from 12 and used 12 rpm for the early mods of the 5in/38. Again, I ask you to produce evidence that RN RoF was 1/2 of what navweaps and Campbell state. The data from HMS Basylisk ( 5 rounds in 17 seconds for a 4.7in single mount) and Scylla (16rpm), suggest that the RN maximum RoF was much higher then 10-12 rpm.

b) Navweaps repeats (anecdotal?) evidence for very high RoF's with the later variants of the 5in/38 but doesn't do the same for RN weapons - clear evidence of bias. This bias extends to the AA FC systems where the USN is praised to high heaven, with no mention of the serious flaws and drawbacks of USN AA FC that have been scientifically documented while the RN system is condemned and every supposed flaw emphasized - another clear example of bias. In actual fact both systems were flawed, as you would expect from 1930s technology, but you'd never know that from the Navweaps site.

D) Here's what Captain Gatch had to say about the relative effectiveness of 5in/38 versus CIWS kill rates:

The first enemy attack was concentrated against the Hornet. South Dakota operated near the Enterprise to provide her protective fire against the attacking aircraft. At 1045 Task Force 16 was attacked by a group of dive bombers. Approximately an hour later the task force was again attacked, this time by some 40 torpedo bombers. A third aerial assault was made with both dive bombers and torpedo bombers, coming in at 1230. South Dakota suffered a 550 lb (250 kg) bomb hit on top of her number one turret. When the action was broken off that evening, the American forces retired toward Nouméa, New Caledonia. The South Dakota was credited with downing 26 enemy planes. She had fired 890 rounds of 5 inch, 4,000 rounds of 40mm, 3,000 rounds of 1.1 inch and 52,000 rounds of 20mm ammunition during the action. Captain Gatch made the following assessment of the relative effectiveness of each weapon type in bringing down enemy aircraft during the action: 5 inch: 5%, 40mm and 1.1 inch: 30% and 20mm: 65%.[3]
[3] United States Navy, AntiAircraft Action Summary, July 1942 to Dec 1942 (Information Bulletin No. 22), p111
USS South Dakota (BB-57) - Wikipedia, the free encyclopedia

Now remember that it was RN Tribal-JKLMN destroyers that had the much heavier CIWS as built, and that is what they went to war with.

e)I'm sorry if I got a bit hot on this one. The problem is that there is clear evidence of bias on the Navweaps site against the RN with an editorial lead-in on virtually every RN weapon telling the reader how bad it was before he/she even gets to the actual data! I used 10rpm for the RN 4.7in (April 1940 twin mount)and 12rpm for the USN 5in/38 (April 1940 single mounts without integral hoists) and these RoFs are supported by actual combat data. If you read Crenshaw's account about USS Maury you will also read about the numerous problems that they had with their 5in FC, guns, and ammunition yet these kinds of cmments don't show up on Navweaps - and I ask you again why not?

f) No one, including me, is saying that 40deg elevation is perfect, but the RN report on Norway states quite clearly that the vast majority of attacks had to come within the envelope of a 40deg gun. Very high level attacks had very little probability of hiting anything anyways - witness Vian's 5knot convoy! and even the Stuka attacks achieved much of what they did beceause they were not engaged at all, not even by the CIWS, and having 5in/38 guns wouldn't change that. Additionally, the RN had a large number of sloops and cruisers that could fire above 70 degs and these were often in company with the 40deg destroyers.

g) Well Torpedo bombers are the one type that we all agree that the 40deg elevation guns would have no problem engaging.

h) The Stuka certainly did not operate at 5-6000m! Typically altitudes were 3000-4000m prior to their dive.



i)

j) Illustrious's AA ammo was fired over many days, and the two Stuka kills were made during the first attack.



Gotta run - more later.

 

[RCAFson]

Oh jeez here we go again, misquoting a highly reputable source for the purposes of an agenda.


The truth is the Mark VIII mount as designed had a muzzle velocity of 2300 as reported by NW. It was increased to 2400 after the introduction of a newly designed round, in 1938, which was not interchangeable (and I suspect one of the reasons behind the notorious unreliability of the 2pdr).

For the record, NW actually says this about the new round, and probably explains why they state the lower figure.....its because the lower figure MV ammunition remained in production and/or use thru-out the war concurrent to the higher velocity round. And whilst they dont say this, it may be that having two incompatible rounds for the same basic gun might explain the reliability issues that plagued the gun during the war.

For the record, the relevant quote from NW is as follows

"A higher velocity projectile was introduced in 1938 and this required a different breech mechanism and other changes to the firing gear. However, guns firing only the older low-velocity projectiles were still manufactured throughout World War II. High velocity and low velocity ammunition was not interchangeable. There were also several other gun variations, as shown in the data tables below".

NW is reporting on the older mechanism and the lower powered round, which is still valid, and not disrespecting the gun or RN equipoment.

Stop trying to put words into the mouth of such a great reference source as NW. It does your otherwise great knowledge on this subject no good at all.

Sorry, but that's not true. The pre 1938 LV 40mm pom-pom = 2040fps not 2300 fps. Campbell states 2400 fps for the HV round.

 

[parsifal]

A)I used the practical rate of fire for both weapons, and actually reduced the 4.7in to 10 rpm from 12 and used 12 rpm for the early mods of the 5in/38. Again, I ask you to produce evidence that RN RoF was 1/2 of what navweaps and Campbell state. The data from HMS Basylisk ( 5 rounds in 17 seconds for a 4.7in single mount) and Scylla (16rpm), suggest that the RN maximum RoF was much higher then 10-12 rpm.

No, you have not. according to Terry Giulan (In an essay dated 2009, entitled "The British High Angle Control System", reproduced in NW, but not where i found it), he provides a clue on the differencews between cyclic rate (or as I call it max rof), and max sustained rof (which I and some others refer to as practical rof). He says:

"Almost all destroyers with 4.7-inch guns had the HE time fuzes set by hand. This affected the firing solution not only by the time setting itself, but also in that the fuze setter became the critical time factor. No matter how fast the guns could fire or how quickly ammunition could be supplied to the mountings, even a well-trained fuze setter needed about 4 to 5 seconds to handle the round and set the fuze properly. Faster speeds invariably resulted in improper fuze settings and loss of effectiveness. These factors encouraged the use of barrage firing as it meant that all fuzes were set the same, thus requiring less time by the manual fuze setters.11 Most larger ships used fuze setting machines, but all of these could only handle one round per barrel at a time, thus slowing the practical rate of fire. An interesting but unfortunate side effect of these fuze setting systems was that the "dead time" between the point that the shell left the fuze setting machine and the point it was fired out the gun needed to be calculated based upon the slowest gun crew on the ship. As the guns were fired by remote control, this effectively meant that all salvos had but a single time setting. Again, this slowed the practical rate of fire".

On top of that, the redesignof the mounting itself wqas not conducive to fast loading. In a static situation, with the gun not moving, I have no problem in accepting 10-12 rpm. But in a real combat situation you have two major constraints that are not present for the 5/38. Firstly you have this manual fuze setting, which at minimum adds 4-5secs to the theoretical max rof. Then you have the poor design of the turret. relative to the gunner, the ammunition supply point was fixed, making it easy to become disoriented. For the single mounts you had a further complication, the hand ramming.

If the theoretical max rof was 12rpm, or 5 secs, you must then add 5 secs for the manual fuze setting and then some unknown time for the turret issues....say 2 secs per round. That reduces the practical rof for the 4.7 down to about 6 rpjm, or more approximately 4-8, which is a better way of describing it, gieven the variable human factors at work.

Now, neither of those constraints affects the Mk 30 5/38 turret. So its practical rof fire is going to be much closer to the max rof. The max rof is not 12rpm for the mk 30, as you are still saying....its 24 rpm. But the practical rof is somewhere between 15-22 rpm. I suspect the director issues you mentioned are the main cause for this downgrading in efficiency. but a more realistic comparison, if we want to use practical rofs, is to estimate the 4.7 at 4-8 rpm, and the 5/38 at 15-22 rpm.

Navweaps repeats (anecdotal?) evidence for very high RoF's with the later variants of the 5in/38 but doesn't do the same for RN weapons - clear evidence of bias.

no. Clear evidence that they have supporting material to inidicate lower standard of efficiency for the 4.7, in comparison to the 5/38. this is not a popularity or political excercise. i think it an excercise in trying to give an accurate assessment of true capabilities of each gun, taking into account various hidden factors. .

This bias extends to the AA FC systems where the USN is praised to high heaven, with no mention of the serious flaws and drawbacks of USN AA FC that have been scientifically documented while the RN system is condemned and every supposed flaw emphasized - another clear example of bias. In actual fact both systems were flawed, as you would expect from 1930s technology, but you'd never know that from the Navweaps site

.

The operational results that we have dont support that claim. US destroyers seem to have been more survivable and achieved overall more efficient standard of fleet and unit protection with their weapons than the RN was able to achieve. There may be good mitigating circumstances for that, but given the FC system is so critical to getting decent results I think it entirely reasonable for NW to take the position they do. Others can perhaps explain the technical side better than I, but the operational results speak to me better than any theoretical technical analysis. the USN destroyers did better than the RN destroyers. Its as simple as that.

Here's what Captain Gatch had to say about the relative effectiveness of 5in/38 versus CIWS kill rates:
Now remember that it was RN Tribal-JKLMN destroyers that had the much heavier CIWS as built, and that is what they went to war with.

The higher standard of CIWs was theoretical rather than actual, but was more or less forced on the RN because of the failure of their 4.7s as a true DP weapon. I say the CIWs were theoretical because really if we are talking British CIWs we are talking 2 pounder guns. these lacked satisfactory performance to be really held up as good or efficient. No tracer, effective range of about 1700m (according to the RN) too many stoppages no relaiable explosive shell. All adds up to an inneffective CIW. So, whereas the USN entered the war with at least a good and true DP main, the RN went to war with neither a good DP main, or a decent CIW either.

I'm sorry if I got a bit hot on this one. The problem is that there is clear evidence of bias on the Navweaps site against the RN with an editorial lead-in on virtually every RN weapon telling the reader how bad it was before he/she even gets to the actual data! I used 10rpm for the RN 4.7in (April 1940 twin mount)and 12rpm for the USN 5in/38 (April 1940 single mounts without integral hoists) and these RoFs are supported by actual combat data. If you read Crenshaw's account about USS Maury you will also read about the numerous problems that they had with their 5in FC, guns, and ammunition yet these kinds of cmments don't show up on Navweaps - and I ask you again why not?

No need to apologise. its allo good. we are still rexchanging information and not insults. Dont agree that NW has much bias, for reasons already given. You are looking at the 5/38 without integral hoists, which makes a huge difference. Its pronbaly no exaggeration to say that more than 80% of 5/38 mounts built were mk 30 hoists with integral hoists. I think it far more relavant to the topic to look at the typical or prevalent type rather than pick an islated or minority failure. and as ive tried to show previously, 10 rpm for the 4.7 is not a realistic estimate of the real rof for this weapon

No one, including me, is saying that 40deg elevation is perfect, but the RN report on Norway states quite clearly that the vast majority of attacks had to come within the envelope of a 40deg gun. Very high level attacks had very little probability of hiting anything anyways - witness Vian's 5knot convoy! and even the Stuka attacks achieved much of what they did beceause they were not engaged at all, not even by the CIWS, and having 5in/38 guns wouldn't change that. Additionally, the RN had a large number of sloops and cruisers that could fire above 70 degs and these were often in company with the 40deg destroyers.

The report you posted does not say what you are claimimg for it. It say, essentially, that those types of attacks that fitted within the envelope they specified, could be countered. It goes on to say, virtually, that in other situations....panic, because you will not be able to hit anything with the equipment we have given you. You cannot make any claims about the 5/38 because it was not engaged in Norway. We need to keep opinion out of the way of known facts.

Well Torpedo bombers are the one type that we all agree that the 40deg elevation guns would have no problem engaging.

Nope, dont agree. Previously posted why, due to slow training rates and rofs, and the short range of the ciws, could not be effectively engaged in many situations. Lucky for the RN, the Germans were even more remiss in not having an effective air launched torp until later in the war.

The Stuka certainly did not operate at 5-6000m! Typically altitudes were 3000-4000m prior to their dive.

I dont know that we can nail a typical approach altide too well. Even at 3-4000 m there would be difficulties for the RN. but even if it was possible, the option was there for the LW simply to fly above the effective ceiling of the gun


j

Illustrious's AA ammo was fired over many days, and the two Stuka kills were made during the first attack.

Regardless, they exopended huge amounts of ammunition for virtually no gain. In any even, wiki suggests thats not the case.....they say that 30000 rounds were expended in the 1st attack. if youve got better, would be great to see it.




Gotta run - more later.[/QUOTE]

 

[fastmongrel]

Jeez will you two give it a break, about 7 pages ago this was an interesting thread.

 

[Glider]

What I find interesting about this thread is how often the volume of the words hide the basic facts and avoid adressing the simple questions.

1) Tribals
RCAF believes that the twin 4.7 was a decent DP gun, so shy did the RN replace a turret with a twin 4in. We know that topweight issues were not the problem. It was done because they needed it.
Generally speaking the RN had the SP 4.7 in destroyers a simple reliable average gun. It put 4in on ships designed to take on aircraft. The RN knew they were taking a chance with the detroyers and designed the DP 4.7 on the LM class. These were heavy, large, expensive and soon dropped.
The JKN and Tribals had 4in installed because they needed it, to pretend otherwise flies in the face of all logic. A comment was made earlier that the RN could have rearmed the Tribals with 8 x 4in, no they couldn't demand far outstripped supply

2 US 5in how good was it.
RCAF believes that it was overated and nothing special. So the question is, why did the RN who first had experience of this weapon on HMS Delhi want to buy as many as they could to install on british Destroyers. It was the awnser to the problem highlighted in question 1

3 Rate of Fire
Much is made about the rof and was it this or that. That isn't the point, the British ships had manual fusing which took approx 4-5 seconds. However it probably had little impact on the rof, but, and this is the real point, it added 4-5 seconds in the cycle between the directions from the director and the gun being fired. An aircraft an go a long way in 4-5 seconds approx 1/3rd of a mile (at 240 mh) and that makes the difference between a hit and a miss.

4) Using a HAA gun to hit a dive bomber before proximity fuzes was almost pontless and it doesn't matter what gun your firing

5) Firing Trials
If anyone believes that what was attained in trials of any weapon in the 1920's to the 1970's has any bearing on real life, needs to have their heads examined. Pick any weapon of any era and you be lucky to find that it does what is says on the tin in trials.

6) AA guns
The first priority of any AA gun Is not to shoot the aircraft down its to stop them hitting you or the target you are defending. An attack where no one was shot down and no one hit is a huge win for the defenders

7) Elevation
The greater the elevation the long you can fire at the target and the better your chance of distrupting the bombers and if you are lucky shoot a couple down. 40 degrees isn't close to sufficient

 

[vinnye]

Glider, I did not know that there was a supply / demand problem with the 4 inch.
Is it possible then that the RN were trying to buy any gun that had some potential as an AA weapon?

 

[parsifal]

Jeez will you two give it a break, about 7 pages ago this was an interesting thread.

Your right. sorry about that. Will ease back a little and give you guys a go. Heated debate, no abuse, and for me some really intersting points. but I can fully understand your frustration. We did hijack things a bit.

 

[RCAFson]

What I find interesting about this thread is how often the volume of the words hide the basic facts and avoid adressing the simple questions.

1) Tribals
RCAF believes that the twin 4.7 was a decent DP gun, so shy did the RN replace a turret with a twin 4in. We know that topweight issues were not the problem. It was done because they needed it.
Generally speaking the RN had the SP 4.7 in destroyers a simple reliable average gun. It put 4in on ships designed to take on aircraft. The RN knew they were taking a chance with the detroyers and designed the DP 4.7 on the LM class. These were heavy, large, expensive and soon dropped.
The JKN and Tribals had 4in installed because they needed it, to pretend otherwise flies in the face of all logic. A comment was made earlier that the RN could have rearmed the Tribals with 8 x 4in, no they couldn't demand far outstripped supply

2 US 5in how good was it.
RCAF believes that it was overated and nothing special. So the question is, why did the RN who first had experience of this weapon on HMS Delhi want to buy as many as they could to install on british Destroyers. It was the awnser to the problem highlighted in question 1

3 Rate of Fire
Much is made about the rof and was it this or that. That isn't the point, the British ships had manual fusing which took approx 4-5 seconds. However it probably had little impact on the rof, but, and this is the real point, it added 4-5 seconds in the cycle between the directions from the director and the gun being fired. An aircraft an go a long way in 4-5 seconds approx 1/3rd of a mile (at 240 mh) and that makes the difference between a hit and a miss.

4) Using a HAA gun to hit a dive bomber before proximity fuzes was almost pontless and it doesn't matter what gun your firing

5) Firing Trials
If anyone believes that what was attained in trials of any weapon in the 1920's to the 1970's has any bearing on real life, needs to have their heads examined. Pick any weapon of any era and you be lucky to find that it does what is says on the tin in trials.

6) AA guns
The first priority of any AA gun Is not to shoot the aircraft down its to stop them hitting you or the target you are defending. An attack where no one was shot down and no one hit is a huge win for the defenders

7) Elevation
The greater the elevation the long you can fire at the target and the better your chance of distrupting the bombers and if you are lucky shoot a couple down. 40 degrees isn't close to sufficient

1) I have answered this several times and even produced and RN document to back up my case:
"9. It appears that enemy aircraft wait about overhead where they are impossible targets for destroyers and difficult for any ship. Steps are being taken to strengthen the short range armament of destroyers who have to operate within the range of dive bombers. It is to be recalled however that except for special aircraft for steep dive bombing and level bombing from considerable heights enemy aircraft must come within the envelope of a 40 degree gun when approaching for an attack."

I think you should, rhetorically, speak to the Admiralty who wrote the above excerpt, and not to me. I have explained why they added a 4in twin - you can choose not to accept my explanation, or the Admiralty's explanation which is summarized above. You keep repeating that the twin 4.7in was a SP gun, even though I have very patiently produced reams of documentation to proof otherwise, including an Admiralty memo, which explicitly states that the 4.7in gun was intended for use against aircraft although the fact that the 4.7in twin had an on mount fuze setter which was directly linked to the AA FC computer should have ended any doubts that you might have had. The 4.7in/50 twin on the LM wasn't dropped, the UK simply couldn't build enough of these complex mounts fast enough to meet demand - heck they were arming some destroyers (OP class) with WW1 vintage 4in MK V single mounts, out of shear desperation and many others with the 40deg 4.7in single.

2) The RN had no intention of buying USN 5in guns or MK37 FC systems - they wanted to acquire them for free under lend-lease, for the simple reason that you yourself have pointed out: "demand outstripped supply" and the UK armaments industry, simply couldn't supply enough UK built guns and FC systems, forcing a request for US supply. Unfortunately, the USA would not build any weapon to UK specs unless it was approved for use by the the US Military (AFAIK only the 6pdr ever met this requirement) which is why Canada built RN spec weapons but not the USA - if the RN wanted to acquire DP naval guns in the USA they had to be USA spec weapons. See North American Supply by Hall for more information on this aspect of lend-lease. For example the RN wanted the USN to adopt the pom-pom so that both navies could have these weapons produced quickly in the USA, but this was turned down and the delay in producing the Bofors 40mm meant that very few USA built Bofors guns were provided to the RN, under lend-lease.


3) All Mk 33 class USN destroyers used a fuze setter (the shell was put in the fuze setter nose first and then had the timing set) which was very similar to that used on RN 4.7in twin mounts. It seems that you don't understand how AA fuze setting works; a shell is placed in the fuse setter, the FC computer predicts the time of flight needed to hit the target and sends this data to the fuze setter and the FC computer predicts far enough in advance to allow to shell to be fused, loaded and then fired according to the salvo interval selected. For an explantion of how RN AA worked, please read: The Gunnery Pocket Book - Part 4

5) Yes, and the practical RoF, as used in combat was 10-12rpm for the RN twin, 12-15 for the USN Mk 33 5in/38 and 15+ for the USN Mk 37. Robert Hughes, an RN gunnery officer gave a real life example of the RN 4.5in twin being fired at 16rpm in predicted fire where each shell had to be fuzed in the fuze setter, and Campbell quotes Illustrious' action report as stating that she fired 3000 4.5in rounds at an average of 12rounds per gun per minute. March reports that HMS Kimberly fired 180 salvos at Narvik, with most having a 5sec firing interval.

6) Vian accomplished just that with his Tribal class destroyers while defending a 5 knot convoy from a day long luftwaffe attack.

7) It all depends on the bomber's elevation. At very high altitudes they couldn't hit ships either.