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RE: Ship Class Design - 10/14/2007 5:39:40 PM   
Curtis Lemay


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quote:

ORIGINAL: ColinWright
You've used this approach before -- arguing from the evidence of games. Simulations can be accurate, but they are not necessarily accurate. I'd be inclined to find supporting statements from some 1940's naval gunnery text before being as certain as you are. For one thing, no doubt 'Task Force 1942' can track shells in the air and distinguish which splash went with which salvo -- but could the actual warships of the era?

Maybe -- but I wouldn't take 'Task Force 1942' as proof that they could.


Thus far, no one has provided a shred of evidence to the contrary about rate of fire. Till then, I've got "Task Force 1942" and WitP on my side. As to whether ships could do it, of course they could, if they've got enough observers. Lots of personel on naval vessels.

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RE: Ship Class Design - 10/15/2007 2:06:29 PM   
rhinobones

 

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quote:

ORIGINAL: Curtis Lemay
Thus far, no one has provided a shred of evidence to the contrary about rate of fire. Till then, I've got "Task Force 1942" and WitP on my side. As to whether ships could do it, of course they could, if they've got enough observers. Lots of personel on naval vessels.


Since you are the one who has made the assertion concerning rate of fire, it is incumbent upon you to provide evidence when the validity is questioned. Your use of a computer toy (WitP) and a simulation that is programmed to support your assertion, is hardly the kind of proof that is compelling.

Regards, RhinoBones

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RE: Ship Class Design - 10/15/2007 7:56:23 PM   
vahauser


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Status: offline 		There is a way to settle this.  Contact the US Naval Academy and find out exactly how warships actually fired their salvos in surface to surface action (shore bombardment and AA were probably handled differently). 

My interpretation of everything I know about naval surface to surface gunnery is as follows:
1. The order to fire is given.
2. The fire-control officer calculates a gunnery solution.
3. The guns are adjusted to the calculated gunnery solution.
4. The guns are fired at the proper moment (usually by turning a key or pressing a button in central fire control, unless the turrets are given independent fire orders, which is uncommon if central fire control is still operational).  What is the proper moment?  The proper moment is that moment during the natural pitch and roll of the ship when not only is the platform most stable, but also as close to the horizontal (relative to the ocean's surface) as possible.  This means that even if a gunnery solution has been plotted and the guns are ready to fire, there is still a waiting period (which can be many seconds in heavy seas) until the proper firing moment (due to the natural pitch and roll of the ship).

What all this means is that there is a big difference between a gun's theoretical rate of fire and a gun's real-life practical rate of fire. 

But the only way to find out for sure is to talk with senior gunnery officers (retired officers are more likely to remember what WW2 naval gunnery protocols were).

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RE: Ship Class Design - 10/15/2007 7:58:59 PM   
ColinWright

 

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quote:

ORIGINAL: Curtis Lemay


quote:

ORIGINAL: ColinWright
You've used this approach before -- arguing from the evidence of games. Simulations can be accurate, but they are not necessarily accurate. I'd be inclined to find supporting statements from some 1940's naval gunnery text before being as certain as you are. For one thing, no doubt 'Task Force 1942' can track shells in the air and distinguish which splash went with which salvo -- but could the actual warships of the era?

Maybe -- but I wouldn't take 'Task Force 1942' as proof that they could.


Thus far, no one has provided a shred of evidence to the contrary about rate of fire. Till then, I've got "Task Force 1942" and WitP on my side. As to whether ships could do it, of course they could, if they've got enough observers. Lots of personel on naval vessels.


It seems technologically unlikely. You appear to look at what a computer does with the data to plot fire -- but this is before computers, remember? You can have one sailor solving multi-variant equations, or a hundred solving them -- the results still won't be forthcoming in two seconds. Add that if I understand what you were asserting correctly, shots would be adjusted based on the trajectories of shells in flight. In 1942, how would that be observed?

You're right that in the country of the blind, the one-eyed man is king, and since no one has presented any solid evidence to the contrary, the model used in your games can be taken to suggest that fire was indeed adjusted as you assert. However, what I said was merely that I don't think you have a foundation for the degree of certainty you've displayed on this point.

I stand by that. After all, I can think of too many computer games and too many scenarios where utterly ahistorical things happen to have a great deal of confidence that the model presented in some other computer games constitutes definitive proof. It's suggestive...but that's about all.

< Message edited by ColinWright -- 10/15/2007 8:02:38 PM >

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RE: Ship Class Design - 10/16/2007 6:03:22 AM   
Curtis Lemay


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quote:

ORIGINAL: rhinobones
Since you are the one who has made the assertion concerning rate of fire, it is incumbent upon you to provide evidence when the validity is questioned. Your use of a computer toy (WitP) and a simulation that is programmed to support your assertion, is hardly the kind of proof that is compelling.


It's a lot more compelling than no evidence at all. WitP definitely uses rate-of-fire in their gun models. Its fan base is chock full of naval specialists. Task Force 1942 was incredibly realistic. They had actually modeled an American Mark 37 gun director.

And, since I'm just using my ship classes in my own scenarios, I'm the only person I have to convince. Anyone else can use what I've compiled, but they aren't forced to. I might also point out that the ships in my scenarios are not going to be doing much if any ship-to-ship combat - just ship-to-shore combat. As such, they're no different than any other artillery.

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RE: Ship Class Design - 10/16/2007 6:11:53 AM   
Curtis Lemay


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quote:

ORIGINAL: ColinWright
It seems technologically unlikely. You appear to look at what a computer does with the data to plot fire -- but this is before computers, remember? You can have one sailor solving multi-variant equations, or a hundred solving them -- the results still won't be forthcoming in two seconds.


Wrong. It's before digital computers, but not analog computers.

quote:

Add that if I understand what you were asserting correctly, shots would be adjusted based on the trajectories of shells in flight. In 1942, how would that be observed?


?? The shots would be adjusted based upon the results of earlier shots. Where they landed relative to the target - not their trajectories.

quote:

You're right that in the country of the blind, the one-eyed man is king, and since no one has presented any solid evidence to the contrary, the model used in your games can be taken to suggest that fire was indeed adjusted as you assert. However, what I said was merely that I don't think you have a foundation for the degree of certainty you've displayed on this point.


No one has presented any evidence to the contrary.

quote:

I stand by that. After all, I can think of too many computer games and too many scenarios where utterly ahistorical things happen to have a great deal of confidence that the model presented in some other computer games constitutes definitive proof. It's suggestive...but that's about all.


I'm going to guess that you've never seen Task Force 1942. That's a lofty vantage point to judge it from.

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RE: Ship Class Design - 10/16/2007 7:19:35 AM   
ColinWright

 

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< Message edited by ColinWright -- 10/16/2007 8:27:05 AM >

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RE: Ship Class Design - 10/16/2007 8:20:25 AM   
ColinWright

 

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quote:

ORIGINAL: Curtis Lemay
I'm going to guess that you've never seen Task Force 1942. That's a lofty vantage point to judge it from.


Yeah. As I say, though, you don't have a very solid basis for being so certain that you're right and your interlocutors wrong. Someday, somebody may actually bestir themselves to go dig up a WW2-era naval gunnery manual. Then we'll know.

I'm actually a tad hazy about what everyone's claiming with such certainty. My own guess -- and it's a guess -- is that the fire control works out a firing solution and then blazes away, correcting as the range changes and as the fall of shot suggests. I doubt if they placidly wait for the results of each salvo before firing off another -- but I also doubt they can know much about the results for shells that are still in flight.




< Message edited by ColinWright -- 10/16/2007 8:23:37 AM >

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RE: Ship Class Design - 10/16/2007 8:27:45 AM   
ColinWright

 

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Status: offline 		It seems to me that one approach would be to look at shell expenditure and length of engagement for some well documented enounters: Bismarck vs Hood and Prince of Wales, Washington vs Kirishima or whatever it was. The ranges and flight times for the shells can be calculated -- and it can be inferred whether the gunners were waiting to see the fall of each salvo before firing another. This will be much more meaningful than claims about the accuracy of Task Force 42 or War in the Pacific.

< Message edited by ColinWright -- 10/16/2007 8:32:23 AM >

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RE: Ship Class Design - 10/16/2007 8:50:52 AM   
ColinWright

 

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Status: offline 		I casually gathered up some data. I cheerfully mixed figures for Britons and Americans, assumed ranges stayed constant, and did various other bad things -- but it's mildly suggestive.

"...Washington soon engaged Kirishima, in the first head-to-head confrontation of battleships in the Pacific war. In seven minutes, tracking by radar, Washington sent 75 rounds of 16-inch and 107 rounds of 5-inch at ranges from 8,400 to 12,650 yards, scoring at least nine hits with her main battery and about 40 with her 5-inchers, silencing the enemy battleship in short order..."

Washington, with nine 16 inch guns, fired 75 sixteen-inch shells. That works out to 8-9 salvos -- or just under one salvo a minute. A bit earlier, blasting away at the Sendai, Washington's main battery seems to have got off five salvos in three minutes.

Assuming that a sixteen-inch shell fired at about 10,000 yards has a flight time of 10-15 seconds, there'd be time to observe the fall of each salvo before the next one was fired. The given rate of fire for a British sixteen inch gun of the era is 1.5 rounds per minute 'as fitted.' That would also work out to about Washington's rate of fire in the engagements with Sendai and Kirishima.

It would appear that the maximum rate of fire is slow enough to permit observation of the fall of each salvo before the next is fired except at extreme ranges. I'd guess that even at 20,000 yards, the flight time for each salvo is around thirty seconds. The theoretical rate of fire would seem to generally be the limiting factor -- which, at TOAW's level of detail, is all that we're interested in.

< Message edited by ColinWright -- 10/16/2007 9:19:14 AM >

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RE: Ship Class Design - 10/16/2007 9:04:32 AM   
vahauser


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Status: offline 		Here is some hard data from the Battle of Surigao Strait.  This battle was perfect for evaluating ideal combat conditions.  The seas were gentle.  The weather was calm.  The Allied Battle Line had been tracking the Japanese for 30 minutes on radar.  The range was short: the Battle Line opened fire at 23,000 yards at 0353 on 24 October 1944. 

The Battle Line fired for 16 minutes until Admiral Oldendorf ordered a cease fire due to reports of friendly fire on Allied destroyers.  In 16 minutes West Virginia fired 93 rounds of 16" shells.  In 14 minutes Tennessee and California fired 69 and 63 rounds of 14" shells, respectively (they opened fire at 0355 and were ordered to fire 6-gun salvoes).  In 10 minutes Maryland fired 48 rounds of 16" shells (opened fire at 0359 and ordered to fire 6-gun salvoes).  Mississippi managed to get off only 1 salvo during the battle and Pennsylvania was unable to obtain a gunnery solution and did not fire at all during the battle.

These were basically perfect conditions for gunnery.  The enemy didn't shoot back at the Allied Battle Line (the Japanese engaged the Allied cruisers instead).  This battle was almost like target practice at short range for the Allied Battle Line.

And yet, what do we find under these nearly ideal conditions?  33% of the Allied Battle Line basically didn't fire at all since they could not even obtain accurate firing solutions.  Of the 4 battleships which did obtain firing solutions we find: 93 rounds for 16 minutes (8-gun salvoes) = approximately 1 salvo per 90 seconds; 69 rounds for 14 minutes (6-gun salvoes) = approximately 1 salvo per 75 seconds; 63 rounds for 14 minutes (6-gun salvoes) = approximately 1 salvo per 85 seconds; and 48 rounds in 10 minutes (6-gun salvoes) = approximately 1 salvo per 75 seconds.

Basically, none of the 4 battleships managed better than 0.8 rounds per minute and the worst was 0.67 rounds per minute.  This is hard data.  Actual combat data.

I've stated it before in this thread and I'll state it again.  There is a big difference between theoretical "proving-ground" rates of fire and practical combat rates of fire.  Practical combat rates of fire are always lower.  Always.  Even under "ideal" combat conditions.

< Message edited by vahauser -- 10/16/2007 9:09:49 AM >

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RE: Ship Class Design - 10/16/2007 9:14:11 AM   
ColinWright

 

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quote:

ORIGINAL: vahauser

Here is some hard data from the Battle of Surigao Strait. This battle was perfect for evaluating ideal combat conditions. The seas were gentle. The weather was calm. The Allied Battle Line had been tracking the Japanese for 30 minutes on radar. The range was short: the Battle Line opened fire at 23,000 yards at 0353 on 24 October 1944.

The Battle Line fired for 16 minutes until Admiral Oldendorf ordered a cease fire due to reports of friendly fire on Allied destroyers. In 16 minutes West Virginia fired 93 rounds of 16" shells. In 14 minutes Tennessee and California fired 69 and 63 rounds of 14" shells, respectively (they opened fire at 0355 and were ordered to fire 6-gun salvoes). In 10 minutes Maryland fired 48 rounds of 16" shells (opened fire at 0359 and ordered to fire 6-gun salvoes). Mississippi managed to get off only 1 salvo during the battle and Pennsylvania was unable to obtain a gunnery solution and did not fire at all during the battle.

These were basically perfect conditions for gunnery. The enemy didn't shoot back at the Allied Battle Line (the Japanese engaged the Allied cruisers instead). This battle was almost like target practice at short range for the Allied Battle Line.

And yet, what do we find under these nearly ideal conditions? 33% of the Allied Battle Line basically didn't fire at all since they could not even obtain accurate firing solutions. Of the 4 battleships which did obtain firing solutions we find: 93 rounds for 16 minutes (8-gun salvoes) = approximately 1 salvo per 90 seconds; 69 rounds for 14 minutes (6-gun salvoes) = approximately 1 salvo per 75 seconds; 63 rounds for 14 minutes (6-gun salvoes) = approximately 1 salvo per 85 seconds; and 48 rounds in 10 minutes (6-gun salvoes) = approximately 1 salvo per 75 seconds.

Basically, none of the 4 battleships managed better than 0.8 rounds per minute and the worst was 0.67 rounds per minute. This is hard data. Actual combat data.

I've stated it before in this thread and I'll state it again. There is a big difference between theoretical "proving-ground" rates of fire and practical combat rates of fire. Practical combat rates of fire are always lower. Always. Even under "ideal" combat conditions.


I look at the salvo rate for the elderly battleships you are discussing -- about one to one and a half minutes per salvo -- and the rates the Washington posted -- forty five seconds to a minute. On the other hand, the older battleships had presumably been fitted with whatever fire control systems the Washington had had two years earlier. It suggests to me that the rate of fire is the critical element. More modern equipment can fire faster and does.


< Message edited by ColinWright -- 10/16/2007 9:17:45 AM >

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RE: Ship Class Design - 10/16/2007 9:29:17 AM   
ColinWright

 

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Status: offline 		Time-in-flight data. One source mentions that the shells of Iowa-class battleships would be in flight for a minute and a half -- but that would be at an extreme range of forty thousand yards.

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RE: Ship Class Design - 10/16/2007 9:44:45 AM   
ColinWright

 

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Status: offline 		Rates of fire. From 'Build a Better Battleship.'

Firepower Table
Year Navy Ship . Rate
1939 Germany Bismarck 3
1942 USA Iowa 2
1936 Germany Scharnhorst 2.5
1923 Britain Nelson 2
1941 USA South Dakota 2
1919 USA Tennessee 1.5
1939 Britain KGV 2
1940 Japan Yamato 1.75
1913 Japan Fuso 1.5
1913 Britain Queen Elizabeth 2
1915 Germany Bayern 2
1919 Britain Hood 2
1935 France Richelieu 2
1935 Italy Vittorio Veneto 1.3
1919 Japan Nagato 1.25

The theoretical rates are conspicuously less than those posted in action. Washington would presumably be about the the same as South Dakota -- but in action she posted at best 3/4's of a minute per salvo rather than the 1/2 a minute per salvo the above would suggest. On the other hand, the rates achieved do seem to be proportional to the theoretical rates. The 1919 Tennessee's fourteen inch guns are 33% slower than the South Dakota's sixteen inch guns -- and sure enough, the fire of her sisters at Leyte was about 33% slower than the Washington's.

Anyway, I couldn't help noticing the Bismarck's listed three salvos per minute. Either we've got a Bismarck propagandist here, or we may be on our way to rehabilitating the Bismarck's reputation against those who like to argue she really wasn't all that good.

...and the poor Japanese and Italians. 1.3 salvos per minute?


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RE: Ship Class Design - 10/16/2007 12:57:20 PM   
vahauser


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Status: offline 		Here is some more hard data.  The cruisers at Surigao Strait fired faster than the battleships.  The Louisville opened fire at 0351 (2 minutes before the battleships) at the short range of 15,600 yards.  Within minutes, the Yamashiro was a burning wreck reduced to 12 knots.  Yamashiro was targeted by 4 battleships and 8 cruisers.  A few minutes later, the Yamashiro was reduced to 10 knots and was burning so brightly that she was a sitting duck target.  The HMAS Shropshire opened fire at 0356 and fired 32 8"-gun salvoes in 13 minutes.  The Phoenix was ordered to fire "rapid and continuous" for a few minutes until being ordered to slow down to conserve ammunition.  While firing "rapid and continuous, the Phoenix was firing 6"-gun salvoes 4 per minute.

Here again, the message seems clear.  Even firing "rapid and continuous" at a sitting-duck target at very short range (the firing range got down to around 13,000 yards before the burning hulk of the Yamashiro drifted away south to sink), the 6" cruiser Phoenix was only capable of 4 rounds per minute.  The 8" cruiser Shropshire was capable of of around 2.5 rounds per minute of rapid fire.  Both 4 rounds per minute for 6" naval guns and 2.5 rounds per minute for 8" naval guns are below the theoretical maximum rates of fire for those guns.  And that is "rapid and continuous" fire.  And also note that only a few minutes of this fire could be managed before orders to slow down to conserve ammunition were given.

Bottom line:  you can basically ignore theoretical rates of fire.  It doesn't matter that the Bismark can theoretically fire 3 rounds per minute and the Yamashiro can only theoretically fire 1.3 rounds per minute because in actual combat both ships will be firing less than 1 round per minute anyway.  And in the rough seas of the North Atlantic in a battle at long range (as opposed to the ideal short-range battle conditions at Surigao Strait), the big guns might only be capable of 0.5 rounds per minute, or even less.

My rough estimate of practical sustained rates of fire in actual combat (at standard combat ranges) based on the above data from Surigao Strait:
Battleships = 0.5 to 1.0 rpm (standard combat range = 25,000 to 30,000 yards)
8" Cruisers = 1.0 to 1.5 rpm (standard combat range = 20,000 to 25,000 yards)
6" cruisers = 1.5 to 2.0 rpm (standard combat range = 15,000 to 20,000 yards)

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RE: Ship Class Design - 10/16/2007 8:34:54 PM   
ColinWright

 

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quote:

ORIGINAL: vahauser


Bottom line: you can basically ignore theoretical rates of fire.


I don't read that as the moral at all. While practical rates of fire do indeed fall below theoretical rates, the practical rates do seem to be proportional to the theoretical rates.

An excellent analogy would be driving my moving van versus driving my car. Now, my moving van has a theoretical top speed of about 70 mph. I can safely drive my car at about 100 mph for an extended period. Can I average 70 mph in my truck when I cross the country? No. Can I average 100 mph in my car when I cross the country? No. However, while I'll usually lay down an average speed of 50 mph over the course of a day in my truck, I'm confident I could average 70 mph in my car without any great effort. (at least, I could if it wasn't for certain noxious government agencies which shall remain nameless).

Showing that practical rates of fire fall below theoretical rates of fire just shows that one damned thing and another keeps popping up in real life. It doesn't show that the theoretical rate of fire isn't proving to be the primary variable governing the eventual outcome. Bob would be incorrect if he calculated AP strengths based on the South Dakota pumping a salvo into the target every thirty seconds. He would not be incorrect if he assigned the South Dakota an AP strength of 33% more than the Yamashiro on the basis of the difference in their rates of fire. Other factors would enter into the picture -- shell weight, fire control, explosive quality, etc, etc -- but I see this as true in principle.




< Message edited by ColinWright -- 10/16/2007 8:46:27 PM >

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RE: Ship Class Design - 10/16/2007 8:48:02 PM   
ColinWright

 

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quote:

ORIGINAL: vahauser


My rough estimate of practical sustained rates of fire in actual combat (at standard combat ranges) based on the above data from Surigao Strait:
Battleships = 0.5 to 1.0 rpm (standard combat range = 25,000 to 30,000 yards)
8" Cruisers = 1.0 to 1.5 rpm (standard combat range = 20,000 to 25,000 yards)
6" cruisers = 1.5 to 2.0 rpm (standard combat range = 15,000 to 20,000 yards)


In this connection, I noticed something. In her encounter with the Bismarck, the Prince of Wales was operating under about as non-ideal conditions as possible. A new crew in a ship that hadn't been fully worked up, continual machinery break downs, getting knocked to **** by return fire...

Yet she averaged almost exactly one salvo a minute. The relationship to the theoretical rate of two salvos per minute seems to hold up. Your old battleships did worse in spite of ideal conditions -- and sure enough, their theoretical rate of fire was considerably slower.


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RE: Ship Class Design - 10/16/2007 11:01:51 PM   
vahauser


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Status: offline 		Colin,

Even "rapid and continuous" fire by modern cruisers at Surigao at short range against a sitting-duck target was less than their maximum theoretical rate of fire.  I don't know if a hard-and-fast correlation exists between theoretical and actual maximum rates of fire.

For example, even if you believe that the Bismark could fire 3.0rpm and the Yamashiro only 1.5rpm as theoretical maximums, I still don't believe that that 2-for-1 ratio would apply in actual combat.  I personally think there are non-linear factors involved that would bring the rates of fire of the two ships much closer together than 2-to-1.  While I believe that in most cases the Bismark would probably, probably, fire a little faster in actual combat than the Yamashiro, I couldn't bet on it.

At this point, I honestly don't know how to quantify actual rates of fire.  And I especially don't know how to quantify actual rates of fire using theoretical rates of fire as a starting point.  I'm not even sure that using theoretical rates of fire is the correct place to start in the first place.  As I said in an earlier post in this thread, theoretical rates of fire might best be applied as a modifier to actual combat rates of fire instead of being the basis of actual combat rates of fire.



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RE: Ship Class Design - 10/17/2007 12:03:50 AM   
ColinWright

 

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quote:

ORIGINAL: vahauser


I personally think there are non-linear factors involved that would bring the rates of fire of the two ships much closer together than 2-to-1. While I believe that in most cases the Bismark would probably, probably, fire a little faster in actual combat than the Yamashiro, I couldn't bet on it.


We don't exactly have a sufficient pool of data, and while I would agree that all sorts of other factors intervene, what we do have suggests that practical rates of fire nevertheless do vary more or less proportionately to theoretical rates of fire. See Washington vs the senior citizens at Surigao Strait. The Washington can fire about 33% faster in theory, and she fired about 33% faster in practice. Add that Prince of Wales -- operating under a mass of adverse circumstances -- nevertheless achieved as fast or faster a rate of fire than the older battleships operating under ideal circumstances.

While at three salvos a minute, shell flight time, time to calculate target solution, etc become more important than at a rate of half that, I'd be prepared to bet the Bismarck could probably get off three salvos for every two the Yamashiro could fire. The difference would be more than a 'little faster.' I can't state so with any authority, but that would be where I would put my money.


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RE: Ship Class Design - 10/17/2007 4:48:38 AM   
vahauser


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Status: offline 		And here is another issue.  According to the Wikipedia, the 15"/47 guns on the Bismark had a theoretical maximum rate of fire of 2.4 rpm.  What this means is that different sources will give different information.  I personally give a lot more credibility to the 2.4rpm number than the 3.0rpm number cited in a different source.  But it is likely that different sources cite different numbers for a variety of different reasons:  wartime propaganda, corporate/govermental disinformation, typographical errors, etc.  My guess is that there are no 100% reliable rate of fire numbers out there.

So, even if we wanted to use theoretical maximum rates of fire as a basis of determining firepower, we are still left to our best guesses as to what exactly those theoretical rates of fire are. 

In any event, the square root of a number provides a very sweet tool to use when trying to quantify non-linear factors:
1.  It compresses numbers.  This is a good thing when you are dealing with educated guesswork since it will produce conservative estimates.  Better to err on the side of caution.  The square root is perfect for this.
2.  Since it is non-linear, it can be used to quantify data that hasn't been (or is not capable of being) identified yet.

Naval ordnance can be classified as heavy (9.4" and above), medium (between 7.2" and 9.4"), light (between 5.5" and 7.2"), and very light (less than 5.5").

Limiting ourselves to heavy ordnance, for now, here is a formula for calculating heavy-gun actual combat rates of fire (ACRoF):
TMx = theoretical maximum rate of fire
ACRoF = SQRT(TMx - 1)

To my mind, this still produces estimated combat rates of fire that are too high, but the numbers are not outrageous.

Bismark TMx = 2.4, ACRof = SQRT(1.4) = 1.183
Yamashiro TMx = 1.5, ACRoF = SQRT(0.75) = 0.866
Iowa TMx = 2.0, ACRof = SQRT(1.0) = 1.0

A different formula would be needed to calculate medium, light, and very light ordnance, but the formulas would all be related in that they would all use SQRT for the reasons cited above.


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Post #: 80
RE: Ship Class Design - 10/17/2007 4:58:38 AM   
Curtis Lemay


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quote:

ORIGINAL: vahauser

Here is some more hard data.  The cruisers at Surigao Strait fired faster than the battleships.  The Louisville opened fire at 0351 (2 minutes before the battleships) at the short range of 15,600 yards.  Within minutes, the Yamashiro was a burning wreck reduced to 12 knots.  Yamashiro was targeted by 4 battleships and 8 cruisers.  A few minutes later, the Yamashiro was reduced to 10 knots and was burning so brightly that she was a sitting duck target.  The HMAS Shropshire opened fire at 0356 and fired 32 8"-gun salvoes in 13 minutes.  The Phoenix was ordered to fire "rapid and continuous" for a few minutes until being ordered to slow down to conserve ammunition.  While firing "rapid and continuous, the Phoenix was firing 6"-gun salvoes 4 per minute.


Note that the crusier data are more telling than the BB data. The BBs just can't get a shell in the air before the last fired reaches the target. But the crusiers can, as the above data show. 4 rounds per minute is a round every 15 seconds; 32 in 13 minutes is one every 24 seconds. The travel time had to be more than a minute at those ranges. Clearly, multiple shells were in the air from each gun.

quote:

Here again, the message seems clear.  Even firing "rapid and continuous" at a sitting-duck target at very short range (the firing range got down to around 13,000 yards before the burning hulk of the Yamashiro drifted away south to sink), the 6" cruiser Phoenix was only capable of 4 rounds per minute.  The 8" cruiser Shropshire was capable of of around 2.5 rounds per minute of rapid fire.  Both 4 rounds per minute for 6" naval guns and 2.5 rounds per minute for 8" naval guns are below the theoretical maximum rates of fire for those guns.  And that is "rapid and continuous" fire.  And also note that only a few minutes of this fire could be managed before orders to slow down to conserve ammunition were given.

Bottom line:  you can basically ignore theoretical rates of fire.  It doesn't matter that the Bismark can theoretically fire 3 rounds per minute and the Yamashiro can only theoretically fire 1.3 rounds per minute because in actual combat both ships will be firing less than 1 round per minute anyway.  And in the rough seas of the North Atlantic in a battle at long range (as opposed to the ideal short-range battle conditions at Surigao Strait), the big guns might only be capable of 0.5 rounds per minute, or even less.

My rough estimate of practical sustained rates of fire in actual combat (at standard combat ranges) based on the above data from Surigao Strait:
Battleships = 0.5 to 1.0 rpm (standard combat range = 25,000 to 30,000 yards)
8" Cruisers = 1.0 to 1.5 rpm (standard combat range = 20,000 to 25,000 yards)
6" cruisers = 1.5 to 2.0 rpm (standard combat range = 15,000 to 20,000 yards)


The WitP rate of fire data were relative values, not theoretical. You're arguing a non-issue.

(in reply to vahauser)
Post #: 81
RE: Ship Class Design - 10/17/2007 5:01:48 AM   
Curtis Lemay


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quote:

ORIGINAL: ColinWright

It seems to me that one approach would be to look at shell expenditure and length of engagement for some well documented enounters: Bismarck vs Hood and Prince of Wales, Washington vs Kirishima or whatever it was. The ranges and flight times for the shells can be calculated -- and it can be inferred whether the gunners were waiting to see the fall of each salvo before firing another. This will be much more meaningful than claims about the accuracy of Task Force 42 or War in the Pacific.


I'll tip my hat to you, Colin. That was quite clever. There could have been pitfalls, of course, since the firing could have been delayed by all sorts of factors, but it appears those pits were missed.

(in reply to ColinWright)
Post #: 82
RE: Ship Class Design - 10/17/2007 5:55:29 AM   
vahauser


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Status: offline 		Curtis,

It's clear from the cruisers at Surigao Strait, that they were firing while previous salvoes were in the air (they were under "rapid and continuous fire" orders [although the fact that there are "rapid and continuous fire" orders in the first place means that this is a special case order and not the standard]).  But that isn't the problem.  The problem is that even under ideal conditions, the cruisers at Surigao Strait were still not capable of achieving their theoretical maximum rates of fire.

You say your ratings are "relative".  Relative to what?  My guess is: relative to theoretical maximum rates of fire.  And how, exactly, are they relative? Are they relative in a direct linear correlation?  Non-linear?  Normalized or otherwise scaled to fit?  All I'm saying is what I stated in an earlier post this thread: your firepower ratings seem "off".  They don't pass my reality checks.  That might not matter because, after all, they are your ratings for you alone.  This is why I'm glad that we finally have an equipment editor with TOAW. 

I quit playing TOAW years ago since there was no equipment editor with which to change ratings that I believed were inaccurate.  But now we have an equipment editor.  Now we can all design scenarios based on our vision of historical reality.

The only reason I entered the discussion in this thread was because I wanted to give you my reasons why I believe your ratings did not pass my reality checks.

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Post #: 83
RE: Ship Class Design - 10/17/2007 9:34:33 AM   
ColinWright

 

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quote:

ORIGINAL: vahauser

4 rounds per minute is a round every 15 seconds; 32 in 13 minutes is one every 24 seconds. The travel time had to be more than a minute at those ranges.


I don't think it does. At a guess, the 8" shells probably had a time in flight of more like fifteen seconds at 15,600 yards -- and the range may well have closed.

At the scale of detail OPART operates at, I would think rate of fire provides a fine yardstick. For one, ships don't seem to have slowed their fire at longer ranges, when the flight time of shells could conceivably become a factor. For another, the actual rates of fire seem to vary pretty much proportionately to the theoretical rates of fire, which they wouldn't if other factors were dominating the equation.

Finally, rates of fire would seem likely to reflect the general quality and modernity of the ship: look at the rates of fire for the older Japanese and American ships and the Italian battleship for evidence of that. I'd be inclined to see ratings based on rates of fire as well as shell weight, etc, as perfectly valid. The more so as in most scenarios we're talking about shore bombardment rather than ship-to-ship combat.

Obviously, the ratings should be relative rather than absolute: I'm not saying we should have ratings based on the Iowa being able to pitch a full salvo into the target every thirty seconds for the entirety of a day-long turn. However, to decide what rating to assign to the Iowa as opposed to the Fuso, it seems just fine. The more so as those ships with high rates of fire seem to have shredded ships with lower rates of fire: Bismarck versus Hood and Prince of Wales, Washington versus Kirishima. It seems to work pretty good as a yardstick.

< Message edited by ColinWright -- 10/17/2007 9:53:35 AM >

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(in reply to Curtis Lemay)
Post #: 84
RE: Ship Class Design - 10/17/2007 10:35:46 AM   
vahauser


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Status: offline 		Colin,

Here is a screenshot taken from a naval gunnery webpage showing the time of flight for a late-war (Baltimore Class) 8" shell. Note the time of flight of 26.07 seconds at 15,600 yards. Note also how quickly the velocity drops off, which partially accounts for the time of flight.

< Message edited by vahauser -- 10/17/2007 10:40:11 AM >

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Post #: 85
RE: Ship Class Design - 10/17/2007 10:38:02 AM   
vahauser


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From: Texas
Status: offline 		Here is the screenshot.






Attachment (1)

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(in reply to vahauser)
Post #: 86
RE: Ship Class Design - 10/17/2007 5:35:05 PM   
Curtis Lemay


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quote:

ORIGINAL: vahauser
You say your ratings are "relative".  Relative to what? 


Relative to each other.

(in reply to vahauser)
Post #: 87
RE: Ship Class Design - 10/17/2007 7:42:59 PM   
ColinWright

 

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quote:

ORIGINAL: vahauser

Colin,

Here is a screenshot taken from a naval gunnery webpage showing the time of flight for a late-war (Baltimore Class) 8" shell. Note the time of flight of 26.07 seconds at 15,600 yards. Note also how quickly the velocity drops off, which partially accounts for the time of flight.


Mmm. And you said flight time at that range 'had' to be more than a minute. I 'guessed' that it was more like fifteen seconds.

In any case, the cruisers at Surigao Strait obviously weren't waiting to see the fall of shot before sending the next salvo on its way -- didn't you say they were firing every fifteen seconds?

Nu? So it would appear the primary limiting factor is theoretical rate of fire. That the practical rate of fire turns out to be less doesn't alter that. It's like my average of fifty miles per hour on the road -- it's basically a function of my top theoretical speed of 70 mph.

< Message edited by ColinWright -- 10/17/2007 7:56:33 PM >

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(in reply to vahauser)
Post #: 88
RE: Ship Class Design - 10/17/2007 9:18:56 PM   
vahauser


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Status: offline 		Colin,

I'm not sure where you got that quote.  I've read every post I've made in this thread, and nowhere did I state that the travel time at 15,600 yards had to be more than a minute.

But that doesn't matter.  What matters is that you and I are largely on the same page.  Whatever quibblings we might have, I've come around to using theoretical maximum rates of fire as the basis for calculating "realistic" combat rates of fire.  Look at my post above where I use TMx to calculate ACRoF (hereby changed to RCRoF, since the word "actual" is misleading so I've changed that word to "realistic").

At this point, my only remaining issue regarding theoretical maximum rates of fire is finding reliable TMx data.  For example, I don't trust that 3.0 TMx for the Bismark's 15" guns i saw in the post above and I trust the Wikipedia TMx of 2.4 more.  But both of those numbers might be incorrect. 

Anyway, once I have reliable TMx data, then I can calculate RCRoF values that pass my reality checks.

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(in reply to ColinWright)
Post #: 89
RE: Ship Class Design - 10/18/2007 6:25:50 PM   
Curtis Lemay


Posts: 12969
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From: Houston, TX
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quote:

ORIGINAL: vahauser

Colin,

I'm not sure where you got that quote.  I've read every post I've made in this thread, and nowhere did I state that the travel time at 15,600 yards had to be more than a minute.


He's more or less quoting me, not you. But I was basing it on the "standard ranges" you listed of 20,000-25,000 yards. Only one of the crusiers had a range given for it. I assumed the rest opened up at max range. At 25,000 yards it probably would have taken more than a minute, or close to it.

(in reply to vahauser)
Post #: 90
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