Destroyers are quite maneuverable and SOP was turn ASAP to present the maximum amount of firepower to attacking aircraft.
Destroyers.....
- Thread starter Lucky13
- Start date
Ad: This forum contains affiliate links to products on Amazon and eBay. More information in Terms and rules
Destroyers are quite maneuverable and SOP was turn ASAP to present the maximum amount of firepower to attacking aircraft.
Glider
Captain
Do you not understand that you need layered defence. Did the example of HMS Tiger whose 6in were deadly against aircraft but still needed 3in and Seact missiles not show this. That the USN with the 40mm and the 5in had the best combination going.
And at the end the 4.7 stops firing and is useless against divebombers whatever you say this is the final fact.
The first changes made were the replacement of the 0.5 with 20mm guns initially 4 then normally increased to 8 with twin mounts replacng singles. The TT were removed for the 4in, then replaced. Later the TT's were removed again and replaced with the 40mm.
On Tribals the 0.5 were replaced with 20mm, then the twin 4in replaced a twin 4.7, then as we have seen 6 x 40mm were added. You cannot make any assumptions about weight unless you know the mounting.
Where on earth did you get the RN saying the 40mm had the same effectve range of 1,700 yards.
Which was nothing compared to other navies
see above re 20mm being added
I admit I don't get this statement can you explain
I have no idea but would assume they had a basic system similar to the US DE's
Well you have failed to convince anyone.
Glider
Captain
In the Med one standard tactic (there were others) against dive bombers was to turn under them to try and make them go past the vertical.
Yes, and the inner layer is the most important of all, and is far more likely to score hits against DBs than HA medium calibre guns. The RN recognized this and developed the quad pom-pom to fill that need.
The simple fact is that topweight compensation was required to fit increased CIWS and the post war Mk VI director.
From the RN:
IJN fleet destroyers used a twin mount that required fixed angle loading above 10 degrees. They could have used the 5"/40 twin mount as on the Matsu's which had loading trays for all angle loading.
The US DEs had no centralized FC until late ~43/44 when the Mk 51 director (similar to the RN Simple Tachymetric Director) was adapted to give some measure of close range AA firecontrol but this was pretty useless against longer range air and surface targets. Most USN DEs used the 3in/50, BTW.
I've never subscribed to "group think" and I doubt you do either.
Last edited:
Glider
Captain
Unfortunately that left them stuck unable to fire anything at a bomber bout to drop its load.
No you are wrong. No changes were made for the addition of 20mm guns and the Tribals were later able take the 40mm without any reductions in weapons. Unless you can support your statement that when the 40mm were added someting was removed from the tribals to compensate.
Good find, but can I ask if you knew the effective range under local non directed control was 1,700 ish yards, why were you claiming 10,000ft?
Good question and I don't know the reason. A guess is that pre war they decided like the UK and USN that fixed one piece shell was unsuitable for a destroyer. By the time 1944 came around they were not in a position to be so fussy.
good info
Also US DDs had rudders and sometimes tactical situation limited the freedom of manoeuvre of individual ships.
Juha
You keep forgetting about the pom-pom.
The 4in twin was added immediately after Norway and the 20mm came after that, and then came the 40mm Bofors - it is pretty easy to see how the topweight progressed.
effective range is synonymous with a reasonable probability of getting hits (IE a well trained crew should hit within that range). It doesn't mean that hits are not possible beyond that range and your average Stuka pilot knew that a single pom-pom hit was likely to ruin his day. Also I provided a quote from March showing that the RN thought it theoretically accurate to 10,000ft.
THE USN's opinion on the Luftwaffe versus the IJNAF:
[/QUOTE]
parsifal
Colonel
We can always find instances where a weapon system has suffered unusual failures or successes. Thats what historical records tend to record....the highs and the lows of something. But that does not mean that an exception makes for the rule.
I have no doubts there were many instances where the 5/38 achieved poor results, including poor rofs in a particular action. i have no doubts that the 4.7 at times achieved outstanding rofs. thats stands to reason. Neither gun was a perfect or complete wepon system.
But the exceptions dont establish the norm for that weapon. The extremes that we can find documentation on will simply show the depths and the highs that a particular weapon system will achieve. Sort of anecdotal snap shots of the statisitcal spread for the weapon.
In my opnion the published max rofs for these weapons are probably the way to start. Ive tried to point out that max rof is different from pracxtical rof, and still believe that to be a factor, but simply to avoid having to go through the pain and suffering of yet another propaganda lecture, lets just agree to use the published max rofs. That puts the 4.7 published figures at 12 rpm for me, and the 5/38 at 15-24 rpm. I do not accept that the British DCT was any faster than the Mk 37 directors, so dont even try to argue that, your just wasting your breath with me. Lets compromise and settle for the middle ground with the 5/38, and say that it had an average rof of 19 rpm. That means on average the 5/38 will be 50% faster than the 4.7, so 4 x 5/38 is the same in terms of output as 6x 4.7.
We also know that the rate of traverse and max elevation rate of the 4.7 twin was slower than the Mk30 turret....roughly half the speed in both planes. Thats been discounted as not being important except at close range, but that is not the case. Even at long range corrections have to be made by both mounts for the changing position of the target, and if that takes longer because of slower traverse rates, thats going to affect the number of times that target can be fired at before the a/c releases its ordinance. Basically, the theory is the same for all directed fire....the course and speed of the target is calculated, the gun moves to a position in the sky where the aircraft is predicted to be be, a shell(s) is/are fused, with time fused shells (either in the turret or in the shell handling areas) , or automatically (in the case of VT), and at the direction of the DCT the gun is fired. If the aircraft position is within the kill radius of the shell, it will be hit, if not, it continues. It should be obvious that AA gunnery is heavily dependant on how many shells can be fired, which is the main reasoining for HAA (the other being it is better suited to providing cover fire for high value targets....the entire screen can be directed to protect critical targets). For the British, one of the disadvantages they suffered was a somewhat lower rof, but also a slower rate of traverse and elevation. There were other issues, that have been argued, but remain unresolved at this point. With a slower rof, and a slower turret, there will be less points that the 4.7 can fire at, and hence less chances for that gun system to hit.
But it is worse than that. Because the 4.7 could only fire at 40 degrees. it could not even fire at targets that approached above a certain altitude and could not fire at targets that remained fairly high and closed the range. If an a/c was at 6000 feet, it cannot be fired on at any closer than 4000m range, whereas a turret with say an 85 deg elevation (what most 5/38 mounts were capable of) can fire until the target is only 500 m horizontal range. Effectively, the 4.7 has a fire opportunity of 4500m, compared to the fire opportunity of 7500, if effective max range is assumed to be 8000m for both weapons. That gives the 5/38 nearly twice the firing time, during which time they will sustain ahigher rate of fire, on the baasis of their quicker training and elevation capabilities. Nothing else can really be argued, because up to now we have been unable to agree on basically anything.
So, in my opinion, its a fiction to argue that the 4.7 was comparable to the 5/38 as a HAA weapon. Moreover, as a fleet scrfeeing unit it was also severely limited. If a Brit destroyer wanted to use its 4.7s to provide cover fire over a high value target, it had to place itself outside the range of its CIWs that could only provide cover fire out to a certain range.
For the USN with its combination of 5/38 and 40mm Bofors, it could provide cover fire from both its main armament and its CIWs as part of a fleet units. I think this was a priceless advantage, and it is relfeceted in the much lower loss rates to air attack for USN Destroyers. British Destroyers had to choose between one or the other. They could move their relative position to the target ship out, so that they could continue to provide 4. 7 fire over the target (and sustaining fire was the issue, even if nothing was hit, disrupting the attack was the important event), or they could forego their 4.7 fire and close right up and rely on their CIWs. But its just not a valid comparison to try and compare the 2 pounder pom pom to the 40mm Bofors, or even the 20mm Oerlikon in my opinion. It was a severely restricted piece of equipment. It suffered from frequent jams, it lack an effective incendiary capability, it certainly did not have an effective celining of 1000feet for all types. It had a max ceiling with the high velocity round (about half the ships in the fleet at a guess) 13000 feet, but max celining is not max effective celing, for the lower powered round, this might be as low as 6000 feet max effective ceiling. But over open sights, the chances of a hit at those ranges.....not good.
These shortcomings in the British Destroyer AA capabilities were painfully brought home throughout the war, and were confirmed in the last campaigns in the pacific, when the British Admirals forced to endure the terrible ordeals of the Kamikaze attacks on their fleet, saw first hand the limitations for the AA screens, and could only compare and lament the relatively poor performance of their own ships to the relatively outstanding performance of the US ships, with their vastly superior combinations of 5/38, 40mm Bofors and Mk 37 directors. They immediately took steps, as best they could to rectify what they could and emulate, as far as they could, the tremdous success that they observed first hand in the US fleet. both Fraser and Rawlings specnt some time on US ships observing for themselves the tremendous effectives of the US systems.
I have no doubts there were many instances where the 5/38 achieved poor results, including poor rofs in a particular action. i have no doubts that the 4.7 at times achieved outstanding rofs. thats stands to reason. Neither gun was a perfect or complete wepon system.
But the exceptions dont establish the norm for that weapon. The extremes that we can find documentation on will simply show the depths and the highs that a particular weapon system will achieve. Sort of anecdotal snap shots of the statisitcal spread for the weapon.
In my opnion the published max rofs for these weapons are probably the way to start. Ive tried to point out that max rof is different from pracxtical rof, and still believe that to be a factor, but simply to avoid having to go through the pain and suffering of yet another propaganda lecture, lets just agree to use the published max rofs. That puts the 4.7 published figures at 12 rpm for me, and the 5/38 at 15-24 rpm. I do not accept that the British DCT was any faster than the Mk 37 directors, so dont even try to argue that, your just wasting your breath with me. Lets compromise and settle for the middle ground with the 5/38, and say that it had an average rof of 19 rpm. That means on average the 5/38 will be 50% faster than the 4.7, so 4 x 5/38 is the same in terms of output as 6x 4.7.
We also know that the rate of traverse and max elevation rate of the 4.7 twin was slower than the Mk30 turret....roughly half the speed in both planes. Thats been discounted as not being important except at close range, but that is not the case. Even at long range corrections have to be made by both mounts for the changing position of the target, and if that takes longer because of slower traverse rates, thats going to affect the number of times that target can be fired at before the a/c releases its ordinance. Basically, the theory is the same for all directed fire....the course and speed of the target is calculated, the gun moves to a position in the sky where the aircraft is predicted to be be, a shell(s) is/are fused, with time fused shells (either in the turret or in the shell handling areas) , or automatically (in the case of VT), and at the direction of the DCT the gun is fired. If the aircraft position is within the kill radius of the shell, it will be hit, if not, it continues. It should be obvious that AA gunnery is heavily dependant on how many shells can be fired, which is the main reasoining for HAA (the other being it is better suited to providing cover fire for high value targets....the entire screen can be directed to protect critical targets). For the British, one of the disadvantages they suffered was a somewhat lower rof, but also a slower rate of traverse and elevation. There were other issues, that have been argued, but remain unresolved at this point. With a slower rof, and a slower turret, there will be less points that the 4.7 can fire at, and hence less chances for that gun system to hit.
But it is worse than that. Because the 4.7 could only fire at 40 degrees. it could not even fire at targets that approached above a certain altitude and could not fire at targets that remained fairly high and closed the range. If an a/c was at 6000 feet, it cannot be fired on at any closer than 4000m range, whereas a turret with say an 85 deg elevation (what most 5/38 mounts were capable of) can fire until the target is only 500 m horizontal range. Effectively, the 4.7 has a fire opportunity of 4500m, compared to the fire opportunity of 7500, if effective max range is assumed to be 8000m for both weapons. That gives the 5/38 nearly twice the firing time, during which time they will sustain ahigher rate of fire, on the baasis of their quicker training and elevation capabilities. Nothing else can really be argued, because up to now we have been unable to agree on basically anything.
So, in my opinion, its a fiction to argue that the 4.7 was comparable to the 5/38 as a HAA weapon. Moreover, as a fleet scrfeeing unit it was also severely limited. If a Brit destroyer wanted to use its 4.7s to provide cover fire over a high value target, it had to place itself outside the range of its CIWs that could only provide cover fire out to a certain range.
For the USN with its combination of 5/38 and 40mm Bofors, it could provide cover fire from both its main armament and its CIWs as part of a fleet units. I think this was a priceless advantage, and it is relfeceted in the much lower loss rates to air attack for USN Destroyers. British Destroyers had to choose between one or the other. They could move their relative position to the target ship out, so that they could continue to provide 4. 7 fire over the target (and sustaining fire was the issue, even if nothing was hit, disrupting the attack was the important event), or they could forego their 4.7 fire and close right up and rely on their CIWs. But its just not a valid comparison to try and compare the 2 pounder pom pom to the 40mm Bofors, or even the 20mm Oerlikon in my opinion. It was a severely restricted piece of equipment. It suffered from frequent jams, it lack an effective incendiary capability, it certainly did not have an effective celining of 1000feet for all types. It had a max ceiling with the high velocity round (about half the ships in the fleet at a guess) 13000 feet, but max celining is not max effective celing, for the lower powered round, this might be as low as 6000 feet max effective ceiling. But over open sights, the chances of a hit at those ranges.....not good.
These shortcomings in the British Destroyer AA capabilities were painfully brought home throughout the war, and were confirmed in the last campaigns in the pacific, when the British Admirals forced to endure the terrible ordeals of the Kamikaze attacks on their fleet, saw first hand the limitations for the AA screens, and could only compare and lament the relatively poor performance of their own ships to the relatively outstanding performance of the US ships, with their vastly superior combinations of 5/38, 40mm Bofors and Mk 37 directors. They immediately took steps, as best they could to rectify what they could and emulate, as far as they could, the tremdous success that they observed first hand in the US fleet. both Fraser and Rawlings specnt some time on US ships observing for themselves the tremendous effectives of the US systems.
Glider
Captain
You mean the pom pom, the weapon wth an effective range of approx 5,100 ft, the pom pom you claim can fire effectively up to 10,000 ft? The pom pom that the RN said was only half as effective as the 40mm against targets apart from suicide aircraft. The pom pom that even the chart you produced showing the arc of fire of an RN destroyer gave a range of approx 7,000ft, that pom pom.
So we agree that the Tribals had the 4in and the 20mm before they received the 40mm guns. Which brings us back to the question you keep avoiding. Of course the toweight increased, the question is, was this a problem for the Tribal class destroyers.
My case is no it wasn't. I support this by the simple fact that the guns were added and no guns were removed to cater for it.
Your case is yes it was a problem but your evidence is -----------? what exactly
Adding a bit of ballast doesn't count as a problem as the ship still functioned in the front line with all her weapons.
There you go again, getting wrapped up in the theory, not the what happened. In Vietnam in theory the F4 didn't need a gun as the Sparrow and Sidewinder were so effective, in the real world they paid a high price for that theory. In WW2 the RN had a theory that their destroyers didn't need a HA gun, in the real world they also paid a price for that theory. In WW2 in theory Enigma was unbreakable, but the germans paid a very high price for that theory. On HMS Tiger in theory we didn't need the Seacat as we had the 3in, in the real world for various reasons we needed the Seacat, at least that was a lesson learnt in peacetime. Do I need to go on, if you wish we could cover the introduction of the M16, the SA80, the decision taken in 1938 that the RN didn't need a single seat fighter, that the Seafire didn't need additional fuel tanks, the list is endless.
I take it you never served in the armed forces. I promise you that what counts at the end of the day is the real world, not the theoretical.
Maybe this had something to do with it
During the 8 months of 1945, when approximately half of the war's kills were made, rounds per bird dropped off. Except for those attacking the fast carrier force, many enemy planes were outmoded types, comparatively slow and operated by unskilled pilots. Gunners had improved in accuracy as a result of increased experience in action and increased training
Last edited:
Shortround6
Major General
If 40 degrees of elevation was considered sufficient for AA work in the late 20s and early 30s why the British spend so much time, money and tonnage getting 8in cruiser guns to elevate to 70 degrees and 6in cruiser guns (twin turrets) to elevate to 60 degrees? Practice fell far short of theory as the loading angle was down around 10 degrees and the elevation and training speeds were too slow to follow any but the slowest of aircraft. Of course at the time of design the standard RAF bomber was the Vickers Virginia.
Top speed 103mph.
As far as strafers go the standard RN fighter in 1930 was the Fairey Flycatcher. The "E" class Destroyers were under construction in 1931 so design and characteristics (armament) had already been decided by 1931.
These were soon replaced by the Hawker Nimrod.
Max speed (not at sea level) under 200mph. Not until 1937 does the RN search for a replacement, well after the Tribal class is in the works.
The Fairey Swordfish doesn't enter service until mid 1936.
What constituted "effective" air defense against such aircraft ( and even that is debatable) was woefully inadequate by 1941/41.
on another point, effective range/altitude is much shorter than max range/altitude. The chances of hitting dropping almost exponentially with range/altitude. When fired straight up the last few hundred ( or even 1000) feet are covered at a comparative crawl. The last 1000ft can take the shell about 8 seconds to cover. That is just due to gravity and not counting air resistance. Even a 200mph airplane is covering about 330ft per second. To have a deterrent effect the pilot needs to know that he is being shot at and that the shells are at least close. This means either tracers or shells that explode close by or in his flight path. Time fuses or shells with self destruct fuses. Self destruct fuses limit the max effective range to the fuse limit regardless of what the theoretical range/altitude is. The Gunner, to be effective needs to know where the shells are going in relation to the plane aimed at. Again tracers or exploding shells provide a reference for the gunner/s. But many shells run out of trace at a distance much shorter than their max range/altitude. at a point a bit longer than the tracer burn out the gunner is no longer aiming at an aircraft but simply filling a portion of the sky with junk and hoping a plane runs into it. Hardly "effective" fire.
Many light AA guns used ring and bead or cartwheel sights that relied on the gunners estimation of both course and speed. Combined with tracer this did work fairly well, tracers (shell bursts) telling you were you should have been aiming several ( or 10-15 seconds for long ranges) seconds ago but they do allow for a correction of fire.
Top speed 103mph.
As far as strafers go the standard RN fighter in 1930 was the Fairey Flycatcher. The "E" class Destroyers were under construction in 1931 so design and characteristics (armament) had already been decided by 1931.
These were soon replaced by the Hawker Nimrod.
Max speed (not at sea level) under 200mph. Not until 1937 does the RN search for a replacement, well after the Tribal class is in the works.
The Fairey Swordfish doesn't enter service until mid 1936.
What constituted "effective" air defense against such aircraft ( and even that is debatable) was woefully inadequate by 1941/41.
on another point, effective range/altitude is much shorter than max range/altitude. The chances of hitting dropping almost exponentially with range/altitude. When fired straight up the last few hundred ( or even 1000) feet are covered at a comparative crawl. The last 1000ft can take the shell about 8 seconds to cover. That is just due to gravity and not counting air resistance. Even a 200mph airplane is covering about 330ft per second. To have a deterrent effect the pilot needs to know that he is being shot at and that the shells are at least close. This means either tracers or shells that explode close by or in his flight path. Time fuses or shells with self destruct fuses. Self destruct fuses limit the max effective range to the fuse limit regardless of what the theoretical range/altitude is. The Gunner, to be effective needs to know where the shells are going in relation to the plane aimed at. Again tracers or exploding shells provide a reference for the gunner/s. But many shells run out of trace at a distance much shorter than their max range/altitude. at a point a bit longer than the tracer burn out the gunner is no longer aiming at an aircraft but simply filling a portion of the sky with junk and hoping a plane runs into it. Hardly "effective" fire.
Many light AA guns used ring and bead or cartwheel sights that relied on the gunners estimation of both course and speed. Combined with tracer this did work fairly well, tracers (shell bursts) telling you were you should have been aiming several ( or 10-15 seconds for long ranges) seconds ago but they do allow for a correction of fire.
From Navweaps:
Coincidentally we know what Edison (for whom Delhi's guns were originally intended) could do in actual combat conditions:
We know that the RN 4.5in twin could fire at 12 RPM per gun for long periods of time in actual combat and on occasion up 16 RPM.
We know that the RN 4.7in twin could fire with a 5sec cyclic rate per gun for long periods of time in actual combat - which is no surprise since the loading tray arrangement of both RN twins was very similar.
We know that the handworked RN 4.7in single could fire at a cyclic rate of 17.6 rpm for at least 5 rounds.
The inescapable conclusion is that the actual combat RoFs were the much the same for the 4.7in twin and the USN 5in/38 single.
It seems very likely that these are the maximum cyclic rates possible under static (ideal) conditions and normally the gun would use the ammunition hoists (use of the hoists was mandatory during predicted AA fire) and so with handpicked guns the max RoF is 15 rpm.
Coincidentally we know what Edison (for whom Delhi's guns were originally intended) could do in actual combat conditions:
We have info from USS Maury:
So 15RPM was the maximum and 12 RPM the actual RoF. Maury also report that two of her 4 guns became unserviceable after this action due to excessive bore enlargement.
We know that the RN 4.5in twin could fire at 12 RPM per gun for long periods of time in actual combat and on occasion up 16 RPM.
We know that the RN 4.7in twin could fire with a 5sec cyclic rate per gun for long periods of time in actual combat - which is no surprise since the loading tray arrangement of both RN twins was very similar.
We know that the handworked RN 4.7in single could fire at a cyclic rate of 17.6 rpm for at least 5 rounds.
The inescapable conclusion is that the actual combat RoFs were the much the same for the 4.7in twin and the USN 5in/38 single.
Last edited:
Shortround6
Major General
No we don't.
you are confusing burst fire with cycle rate.
5 rounds in XX seconds is not equal to the cycle rate because you have left out one loading/ramming cycle. You started the watch with a loaded gun going bang and ended with a loaded gun going bang. The time to load the first round is not counted and time for the gun to recoil and run out from the 5th shot is not counted.
It is an impressive performance but only includes 4 loading cycles.
Using action reports is informative but will always be lower than "theoretical" rates of fire. Guns in action are only fired by director control when on target and when either ALL guns are ready or the majority of guns are. Many directors had "ready lights" showing which guns/turrets were loaded and ready to fire and the director crew would wait for all lights/indicators before firing so the cycle rate for the ship was governed by the slowest crew/mount. Guns were also often fired only at a certain point in the ships roll. So there may be a certain delay in firing until that point is reached. The 5in/38s (and darn few other destroyer main guns) not being stabilized. Trying to fire on the roll means the guns are chasing the target/indicators in elevation constantly making loading a bit slower.
You don't know that the gun was loaded prior to the first round being fired - in fact why would it be, since the gun was undergoing firing trials?
I assume that you mean that the 5in guns were stabilized. RN destroyer guns were fired via stabilzed sights (as per the USN, albeit using a gyro in the director, rather than a below decks gyro) and the firing was continuous except in very heavy seas where firing at some point in the roll might be used instead.
Last edited:
Some of my earlier posts regarding 40 deg elevation:
We know from actual combat that when USN destroyers were singled out by divebombers that they seemed to sink just like RN destroyers - what saved USN destroyers from suffering losses at the same rate as RN destroyers was the generally weaker opposition that they faced and the fact that they most often met IJNAF aircraft while performing escort duties for other higher value targets mainly carriers. I've tried to show the trade-offs made by both the RN and USN in selecting 4.7in/5in gun elevation and how a lower gun elevation creates less topweight, thus allowing for a heavier CIWS.
We know from actual combat that when USN destroyers were singled out by divebombers that they seemed to sink just like RN destroyers - what saved USN destroyers from suffering losses at the same rate as RN destroyers was the generally weaker opposition that they faced and the fact that they most often met IJNAF aircraft while performing escort duties for other higher value targets mainly carriers. I've tried to show the trade-offs made by both the RN and USN in selecting 4.7in/5in gun elevation and how a lower gun elevation creates less topweight, thus allowing for a heavier CIWS.
vinnye
Senior Airman
I agree that any destroyer on its own was in grave danger from air attack.
The RN lost many destroyers that were acting on their own or in loose cooperation with other ships, usually withdrawing troops without air cover.
They were attacked by very professional bomber crews who had a lot of experience and were well motivated.
I do not think that USN destroyers in the same position would have fared any better.
The RN lost many destroyers that were acting on their own or in loose cooperation with other ships, usually withdrawing troops without air cover.
They were attacked by very professional bomber crews who had a lot of experience and were well motivated.
I do not think that USN destroyers in the same position would have fared any better.
Shortround6
Major General
And you don't know the gun was unloaded at the start.
Your quote "During gunnery trials in 1930, HMS Basilisk'' was able to fire "...five rounds in 17 seconds."
If it started loaded that is a cycle of rate of about 4 seconds or 15 round per minute which is quite good. it is also believable considering later performance. A cycle rate of 3.4 seconds or 17.6 rpm is just a bit too good considering the later performance.
The HMS Basilisk also used the 30 degree elevation mount. We also do not know the conditions of the trials. Speed and sea conditions affected the destroyer or type, speed (if any) of the target. Was the destroyer in calm water doing 12-15kts firing at a stationary/moored target at close ( under 3000yds) range that required little or no change in elevation and only minor changes in train? Where was the gun in relation to the ammunition hoist/feed or for 5 rounds was that even a consideration?
The L&Ms with the big 4.7s suffered a drop in rate of fire with the turrets rotated 90 degrees from the center line because the ammunition hoists did not turn with turret calling for a longer, more confused pathway for the ammunition numbers to follow.
With the Ls part of the 1937 Naval estimates ( budget?) and Ms part of the 1939 it can be seen that at least some in the RN were not satisfied with the twin 4.7 as used in the Tribal and J&K classes. The Mark XX twin hada few problems of it's own and shows the problem of trying to combine both good surface gunfire with a DP mount. The Americans sacrificed some surface capability ( muzzle velocity/range) for the DP capability.
You can find "burst fire" ratings for a number of land artillery pieces. Vickers offered a SP 155 gun that could fire 2 rounds in 8 seconds, 3 rounds in 13 seconds or an "intense" rate of 6 rounds per minute. Sustained of 2 rounds per minute for one hour. The last two firing rates may have more to do with barrel cooling and barrel life than the loading arrangements. The last certainly does. There is no way a gun using 100lb shells and bagged charges "cycles" at 4 seconds.
I did not make up "burst fire", it exists and can be found. It is perhaps more useful for advertising or press releases than evaluating combat performance.
The US 5in/38 guns were not stabilized. Heavy seas is subject to interpretation and heavy seas slow the rates of fire by throwing the loading numbers (crew) around slowing the work at the guns. Even before WW I most knowledgeable gunnery officers figured that the rate of fire "in combat" for medium sized guns on cruisers would be 1/2 to 1/3 what was achieved during the summer annual "shoots". Destroyer guns using lighter ammunition ( and cased charges rather than bagged) would show less of a fall off until the weather got really bad.
Shortround6
Major General
It depends on the type of attack. EVERYBODY's destroyers were woefully ill prepared for dive bomber attacks in 1939-42. The Americans could do much better against level bombers attacking at 8-15,000ft but since attacks from that height, even by formations of several squadrons, seldom hit anything anyway it is a bit hard to prove.
Torpedo bombers could be engaged by just about anybodies destroyer guns. Fire control may change from navy to navy.
The 5in/38 may be over rated in the early part of the war but since it was on hand and in wide use when the proximity fuse (VT) showed up it's ability took a sudden leap upward (subject to ammo availability). Navy's with limited ability ( in elevation limits, loading limits, training speed limits) needed now guns/mounts to take full advantage of VT fuses even if they could make them.
vinnye
Senior Airman
Totally agree, everyone was ill prepared upto 1942 - lessons being learned the hard way!
Also agree hitting a moving ship from 8,000 + feet was difficult, even if it was an aircraft carrier - Illustrious dodged a lot!!!
There are some examples of medium level bombing success eg Tirpitz was hit several times by Lancasters, but she was atationary.
Also agree hitting a moving ship from 8,000 + feet was difficult, even if it was an aircraft carrier - Illustrious dodged a lot!!!
There are some examples of medium level bombing success eg Tirpitz was hit several times by Lancasters, but she was atationary.
I don't know that it was unloaded but I doubt the trials were conducted to mislead anyone, but by the same token we don't know the conditions under which Delhi's handpicked guns achieved their stated ROFs either, or for how long.
Actually the LM class guns appear to be optimized for fire on the beams with loading becoming less efficient towards the centreline.
If the director sights are stabilized, the guns are effectively stabilized as well.
Shortround6
Major General
I am not saying the trials were to mislead anyone at the time. If the writer knew what he saying and assumed the reader understood his term or phrase there is no misleading. If someone 70 years later wants to read something more than is stated based on a short excerpt?
The L&M guns, at least according to a drawing in "Destroyer Weapons of World War II" British section by Peter Hodges, show four tubes in the ammunition hoist. The "front" two are the shell hoists and the rear two are the cartridge hoists. Pretty well laid out for firing along the axis of the ship. (no mention of how X turret was laid out but perhaps mirror image? shell hoists towards muzzle with guns pointed aft?) Since the ammunition hoist/trunk does not rotate when the guns are pointed 90 degrees to the broadside, say to starboard, the two shell hoists are next to the left hand gun and the two cartridge hoists are next to the right hand gun. The hoists being between the guns. This requires extra movement (distance) to get the right components to correct loading trays and a bit of interference as the left hand gun cartridge handler in order to place the cartridge in the loading tray has to stand in or very near where the left hand gun shell handler has to stand to get the shell out of the hoist. A similar dance has to be performed by the loaders of the right hand gun with the shell handlers dealing with 62lb shells. How this is "optimized for fire on the beams" is beyond me.
"If the director sights are stabilized, the guns are effectively stabilized as well"
If this was true a lot of navy's spent a lot of money on stabilized gun mounts that they didn't need to. The director sight may be stabilized and stay pointed at fixed point in space as the ship rolls, pitches and yaws beneath it but the gun barrels are going to be waving all over the place. You can rig the firing circuits to fire when the barrels are aligned with the sight and get sort of the effect of a stabilized gun but that plays merry h**l with the rate of fire as it may take a number of seconds for the natural motion of the ship to bring the guns into alignment with the sight.
The L&M guns, at least according to a drawing in "Destroyer Weapons of World War II" British section by Peter Hodges, show four tubes in the ammunition hoist. The "front" two are the shell hoists and the rear two are the cartridge hoists. Pretty well laid out for firing along the axis of the ship. (no mention of how X turret was laid out but perhaps mirror image? shell hoists towards muzzle with guns pointed aft?) Since the ammunition hoist/trunk does not rotate when the guns are pointed 90 degrees to the broadside, say to starboard, the two shell hoists are next to the left hand gun and the two cartridge hoists are next to the right hand gun. The hoists being between the guns. This requires extra movement (distance) to get the right components to correct loading trays and a bit of interference as the left hand gun cartridge handler in order to place the cartridge in the loading tray has to stand in or very near where the left hand gun shell handler has to stand to get the shell out of the hoist. A similar dance has to be performed by the loaders of the right hand gun with the shell handlers dealing with 62lb shells. How this is "optimized for fire on the beams" is beyond me.
"If the director sights are stabilized, the guns are effectively stabilized as well"
If this was true a lot of navy's spent a lot of money on stabilized gun mounts that they didn't need to. The director sight may be stabilized and stay pointed at fixed point in space as the ship rolls, pitches and yaws beneath it but the gun barrels are going to be waving all over the place. You can rig the firing circuits to fire when the barrels are aligned with the sight and get sort of the effect of a stabilized gun but that plays merry h**l with the rate of fire as it may take a number of seconds for the natural motion of the ship to bring the guns into alignment with the sight.
