ROF of AT guns

[Thin Red Line]

I recently played a scenario as Germans and i was amazed by the rate of fire of the 88mm Flak guns : less than 10 seconds beetween two scoring hits (armored targets at 900m closed to each other).

The experience of the crew was elite but i still wonder if such a performance was possible during actual battles.

[rexford]

Originally posted by Thin Red Line:

I recently played a scenario as Germans and i was amazed by the rate of fire of the 88mm Flak guns : less than 10 seconds beetween two scoring hits (armored targets at 900m closed to each other).

The experience of the crew was elite but i still wonder if such a performance was possible during actual battles.

6 shots per minute is reasonable rate of fire for many weapons in combat situation, which is about 10 seconds between shots.

If two targets are at about the same range and the first shot is a hit and a clear knockout punch, then the second shot/target can be taken without having to change the range setting.

Time between shots would be greater for misses since revised range estimate would be needed and gun aim would be changed. Hitting a target without clear sign of knockout might result in continued firing at target.

If 88mm Flak were trying for max rate of fire without caring about anything else, rate of fire would be much higher than 6 per minute. A Tiger tank can probably shoot at 6 per minute.

[Michael Emrys]

Someone correct me if I am mistaken, but in general, towed guns tend to have higher rates of fire than the same gun on a vehicle due to the larger crews and greater freedom of movement compared to the confined space in a vehicle, especially one with an enclosed turret.

Also, I would expect a Flak gun to be designed from the outset to maximize RoF.

Michael

[Redwolf]

Originally posted by Michael emrys:

Someone correct me if I am mistaken, but in general, towed guns tend to have higher rates of fire than the same gun on a vehicle due to the larger crews and greater freedom of movement compared to the confined space in a vehicle, especially one with an enclosed turret.

I don't think the guns have a higher ROF that tanks with the same gun in CMBO.

But your point is very good, and triggers another one: the open-top TDs with two loader crewmen (M10, M18) should have a higher ROF than a tank as well.

[ June 10, 2002, 10:30 AM: Message edited by: redwolf ]

[ParaBellum]

AFAIK trained 8,8 Flak crews could fire 15-20 rounds per minute.

So, in CMBO their ROF seems to be a little low.

And two hits within 10 seconds, especially by an elite crew, seems quite reasonable to me.

[Redwolf]

Originally posted by ParaBellum:

AFAIK trained 8,8 Flak crews could fire 15-20 rounds per minute.

So, in CMBO their ROF seems to be a little low.

Almost all units in CMBO have substancially less ROF than the historical counterparts could reach.

Neither real world nor CMBO units could sustain the highest ROF very long, for reasons around exhaustion and weapon wear, and also for expending too much ammo. CMBO does model running out of ammo and it could easily model crew exhaustion based on shots fired the last minutes.

It would be hard to make a suitable computer model to decide when the unit should switch to "burst" rof.

Imagine BTS tried to do that: you would bet that the TacAI would always blow lots of ammo when you don't want it. And you would always have tired loaders when you actually need high (or even normal) ROF.

So I guess it is not a bad compromise overall, however it nags me a little bacause it contributes to the lack of defensive benefits in CMBO.

[JasonC]

Actually I don't think crew exhaustion would be much of a problem. I've fired much larger cannons than the typical ones aboard CM vehicles and exhaustion of a loader is a long way down the pike. You aren't going to blow out just from a short intense flurry. When 4 batteries of 105s put out 18,000 rounds in 53 hours (a level actually reached in some combat AARs), you get *exhaustion*. Exhaustion takes hours and tons, not minutes and pounds.

I also don't think cramped quarters are much of a problem for ROF, except for very tight vehicles like the Hetzer. In most, you have room to move the shells around. For sustained high ROF, you might encounter problems with round stowage, in the sense of running through everything in the ready racks and needing to fish additional rounds out of the floor, or wherever. After you'd shot off a third to a half of the ammo load, perhaps.

Much higher ROFs are possible, but it is questionable how accurate the rounds will wind up being. The gunner has less time to point the thing in the right direction. If you are just throwing HE at an area target where you've already found the range, then that wouldn't be much of an issue. For any point target, or anything moving, or the first several shots at anything while still finding the range, it can be.

Incidentally, in CM one important issue with ATG rates of fire is rotation to track moving targets. The bigger AT guns rotate slowly, and especially at closer ranges, where the angles something moves through are bigger, that can seriously depress the ROF. The gun is turning instead of firing, even with the round ready to go (no "reloading" in the info window). More than is realistic, in fact, because the Tac AI doesn't lead things properly. You get better ROF out of lighter guns that rotate better. In CM only, mind.

[aka_tom_w]

Originally posted by redwolf:

</font><blockquote>quote:</font><hr />Originally posted by ParaBellum:

AFAIK trained 8,8 Flak crews could fire 15-20 rounds per minute.

So, in CMBO their ROF seems to be a little low.

Almost all units in CMBO have substancially less ROF than the historical counterparts could reach.

Neither real world nor CMBO units could sustain the highest ROF very long, for reasons around exhaustion and weapon wear, and also for expending too much ammo. CMBO does model running out of ammo and it could easily model crew exhaustion based on shots fired the last minutes.

It would be hard to make a suitable computer model to decide when the unit should switch to "burst" rof.

Imagine BTS tried to do that: you would bet that the TacAI would always blow lots of ammo when you don't want it. And you would always have tired loaders when you actually need high (or even normal) ROF.

So I guess it is not a bad compromise overall, however it nags me a little bacause it contributes to the lack of defensive benefits in CMBO.</font>

[Andreas]

Originally posted by aka_tom_w:

[QB(Hint: I play the Allies mostly and the tanks usually die early and they ALWAYS have plenty of ammo left over, I have never run out of AP shot as the Allies in a tank dual because my tanks ALWAYS die before they run out of ammo so I'm a HUGE fan of "burst mode" ! )

[/QB]

I am not quite sure how realistic that would be for AP. While I can see the point for HE (as long as you are remotely near target, you are likely to do damage, or at least suppress), for AP aiming is crucial. You miss even by an inch, you do not achieve anything. Does anyone have historical examples of tanks or guns going all-out when firing AP?

[aka_tom_w]

Originally posted by Andreas:

</font><blockquote>quote:</font><hr />Originally posted by aka_tom_w:

[QB(Hint: I play the Allies mostly and the tanks usually die early and they ALWAYS have plenty of ammo left over, I have never run out of AP shot as the Allies in a tank dual because my tanks ALWAYS die before they run out of ammo so I'm a HUGE fan of "burst mode" ! )

I am not quite sure how realistic that would be for AP. While I can see the point for HE (as long as you are remotely near target, you are likely to do damage, or at least suppress), for AP aiming is crucial. You miss even by an inch, you do not achieve anything. Does anyone have historical examples of tanks or guns going all-out when firing AP?[/QB]</font>

[rexford]

One other issue that retards tank ROF is fumes in the turret, which could become quite thick in some vehicles. ATG crews don't face the same problem, although they must put up with HE shells and fragments flying by their heads while they do their thing.

The fumes issue is what kept the 100mm gun out of the IS-2 turret during late 1944, among other factors.

[StellarRat]

Don't forget that a crew under fire will probably have problems maintaining a high rate of fire and probably won't be aiming as carefully either. There are so many variables!

[aka_tom_w]

Originally posted by StellarRat:

Don't forget that a crew under fire will probably have problems maintaining a high rate of fire and probably won't be aiming as carefully either. There are so many variables!

You might also conclude a crew under fire is peaking on Adrenaline and they may not aim well but I'll bet the loader is loading as fast as he can because if the crew is being fired at upon their lives depend on it.

My limited readings of Allied tank battles in WWII give me the impression that when the TC says "we've got a HIT "pour it on" the ROF roughly doubles as the gunner and loader go into burst mode to destroy the target before it fires back and gets a hit.

Same for HE only its easier because as Andreas pointed out, you don't have to be so accurate. I have read accounts of 75 mm Shermans knocking down small wooden houses (reduced to rubble) in under a minute while firing 7 HE rounds one after another rapidly.

Thats why there is a READY rack with HE and AP available so the loader can switch into "burst mode" when they need a minute or so of sustained rapid ROF IMHO.

-tom w

[ June 10, 2002, 02:23 PM: Message edited by: aka_tom_w ]

[Paul Lakowski]

while ROF in tanks can be slow 3-4 RPM on most russian tanks and ~ 6-8 RPM on other tanks, the rate determining step is the loader. But with most ATG there where 2 or more loaders so I'd expect they would get much higher ROF. This probably explains why Soviet ATG accounted for most german tanks.

Burst fire is every thing in fighting cause most units [tanks or ATG] don't last before there suppressed or destroyed.

[Michael Emrys]

Originally posted by JasonC:

I also don't think cramped quarters are much of a problem for ROF, except for very tight vehicles like the Hetzer. In most, you have room to move the shells around.

My thought was that the larger gun crews with towed guns have more people selecting, preparing (fusing if necessary), and passing ammo. So instead of one guy fishing around in the ready locker trying to find the right round, all he has to do is reach back and somebody puts it in his hands. I would expect that to be a major time saver, but as I have never crewed either type of weapon I am only speculating.

Michael

[JasonC]

If you aren't going to bang your elbows (as in a Hetzer), the round is in the ready racks (not in the floor), the round is self-contained (not seperate loading of powder behind it, as in 122mm and above), the round doesn't have to be hydraulicly rammed (100 lb shells in 150mm and above) - you aren't going to be appreciably faster or slower, one way or the other.

You might be somewhat faster with 40mm and below, because those you can easily "one hand". But anything in the 50mm to 105mm range, with the above factors true, you just aren't going to be appreciably faster or slower due to minor differences in weight of shell alone.

The number of motions you have to make is basically the same. With a heavier shell like a 105mm, they are slightly harder on you, in muscle terms. But you can move just as rapidly for well longer than the length of typical engagements. You are not continually lifting anyway. Your muscles have short periods to rest, as you perform the other "light" motions in the firing process.

Go to a gym, to a military press machine (or pick up a curl bar). Put the weight pin on 30 lbs. Do 10-12 reps, with a full 2 second pause between each. Put the weight pin on 10 lbs, same number of reps with same length of delay between (representing other motions you must perform). Do you do them scads faster? You do not.

Put it on 100 lbs and make yourself walk over to the door and back between each lift, and yes you will be a lot slower. So a 150mm field artillery piece will be slower than a medium tank caliber gun. But there isn't going to be a noticable difference for the smaller ones.

It is not a continuous function of the weight of the shell. It is a threshold effect. If the shell is light enough to lift easily, lighter still doesn't make the motions go any faster.

[StellarRat]

Originally posted by aka_tom_w:

</font><blockquote>quote:</font><hr />Originally posted by StellarRat:

Don't forget that a crew under fire will probably have problems maintaining a high rate of fire and probably won't be aiming as carefully either. There are so many variables!

You might also conclude a crew under fire is peaking on Adrenaline and they may not aim well but I'll bet the loader is loading as fast as he can because if the crew is being fired at upon their lives depend on it.

My limited readings of Allied tank battles in WWII give me the impression that when the TC says "we've got a HIT "pour it on" the ROF roughly doubles as the gunner and loader go into burst mode to destroy the target before it fires back and gets a hit.

Same for HE only its easier because as Andreas pointed out, you don't have to be so accurate. I have read accounts of 75 mm Shermans knocking down small wooden houses (reduced to rubble) in under a minute while firing 7 HE rounds one after another rapidly.

Thats why there is a READY rack with HE and AP available so the loader can switch into "burst mode" when they need a minute or so of sustained rapid ROF IMHO.

-tom w</font>

[Londoner]

Surely Jason with more men and more space, loading is going to be easier and quicker when operating an ATG in contrast to a AFV.

[JasonC]

I'm sorry Londener, I don't see why at all. Can 10 people on a wide field touch the end of their noses faster than I can alone inside an automobile? No. Why not? There are more of them and they have more space to swing their arms. That is true, but it doesn't matter. Because the task is so trivial even inside the auto that those "extras" don't matter a tuppenny darn.

Loading a medium caliber gun is slightly more involved than touching the tip of your nose. But it is not brain surgery. You don't need more room than room to move your arms and swivel your hips while holding the shells. You don't need more men than can pick up and shove the shell into the breach, which for any given shell is precisely one.

With larger crewed field guns, loaders take turns and have more time to do other things like prep additional shells, and carry them around (e.g. from the prime mover to the gun position). In AFVs, prepped shells are kept on the ready rack to avoid having to do this in action, and of course the vehicle carries the ammo without any more ado.

If you have semi-seperate ammunition like US 105s, somebody has to cut the powder charges to the right size for the range of the mission, unscrew the shell case, put in the powder, rescrew it, find the right fuse, put in on with the right wrench, and then haul the prepped shell over next to the gun for the actual loader to pick up. If you are loading 203mm shells that weigh 200 lbs, you need two men to carry the shell in its cradle and hydraulics to get it into the breech.

These are the reasons real world heavy artillery pieces have larger gun crews. But none of them apply, at all, to medium caliber pieces inside AFVs with prepped single-loading ammo on their ready racks. Loading those is comparatively touching the end of your nose.

[Andreas]

ROF for 8,8cm Flak different varieties, quoted from Piekalkiewicz 'Die 8,8cm Flak im Erdeinsatz':

8,8cm Flak 18 and 36: 15-20 rounds/min

8,8cm Flak 37/41: 15-20 rounds/min

8,8cm Flak 41: 22-25 rounds per minute

I guess they changed something about the layout of the Flak 41 that enabled the loaders to touch their noses faster.

What does a Tiger manual say about ROF?

[JasonC]

If you think there is a meaningful difference between a shot every 3 seconds and a shot every 2 1/2 seconds, then you are probably smoking something. The target is dead in 8-9 seconds if you are at all accurate, either way. ROFs that high are surge figures and so close that only minor factors will easily swamp them.

[Andreas]

Thank you for living up to your sig Jason.

I believe there is a meaningful difference - why would they have increased ROF otherwise? Answers on a postcard.

Does this meaningful difference come in at ground-level? Well, probably not. Does it matter for AA use? Don't know, but if your gun is not radar controlled, the more HE you can put in the air in a given time, the greater your chances of taking out that pesky Lancaster. What was the designation of the 8,8cm gun? Oh that's right - 'Flak'.

Having said all that, I am really bad at comparing apples to oranges, so I leave it up to you to draw definitve conclusions.

Now coming back to the real question - what was the theoretical ROF of the 8,8cm guns in:

a) Tiger I

Tiger II

c) Nashorn

d) Elefant

e) Jagdpanther

Was it as high as 22-25 rounds/min? If not, was it not as high because the tank crews spent more time touching up their noses? Inquiring minds want to know.

[Londoner]

I see your arguement Jason, I think. Your saying there is an optium prep' time to firing a medium calibre gun regardless of crew numbers, space etc. However if three men, ie loader, gunner and TC are the "optium", why have 7-8 men on a 88mm PAK 43? Remember we're talking about ATGs here not howitzers or infantry guns.

The 88 is a good example andreas. It would be interesting to know the figures.

[Andreas]

If someone is taken in by the argument 'If you think there is a meaningful difference between a shot every 3 seconds and a shot every 2 1/2 seconds, then you are probably smoking something.':

I just went through the very simple math because I am bored. Assuming a net explosive/shrapnel load of 6.45kg (total weight of shell 9kg, propulsion load 2.55kg, no figure for actual explosive load given) for the 8,8cm Sprenggranate:

Lower end of ROF:

Flak 18 and 36 deliver 97kg on target in a minute

Flak 41 delivers 142kg (~47%+)

Higher end of ROF

Flak 18 and 36 deliver 129kg on target in a minute

Flak 41 delivers 161kg on target (~25%+)

This matters when fighting infantry, or acting as artillery, or fighting planes. It does not matter when fighting tanks. Neither does Jason's experience as a howitzer gunner.

[YankeeDog]

This has been discussed before, but it's quite relevant to what's being discussed here. So I'm going to add it to the soup.

There's already been mention of ready racks and the easy access to ammo stored there.

When and if Battlefront gets around to modeling higher ROF for AFVs after range and bearing have been found (which makes sense to me), the model would also need to reflect the number of rounds available in the ready rack. Some AFV types (for example, the T-34/76) had a rather small ready rack. Preumably, the crew would only be able to maintain the "burst" fire rate as long as their supply of whatever shell type they were firing (HE or AP) on the ready rack held out.

I assume that tank crews would replenish the ready rack at the earliest available opportunity, but I can think of numerous times in my CM games where a tank would have run out of ready-rack rounds because it was firing more or less constantly, or moving between firing.

Anybody have any idea if the ready rack could be easily replenished while the tank was moving? My guess is no unless the tank was moving over a smooth surface like a flat stretch of road. I'm also guessing that another crewmember needed to help the loader move rounds up from the floor lockers and into the ready racks (talking about the sherman here - the only WWII tank I've ever been inside), so the tank should then temporarily "lose" a crewmember while ready rack replenishment is going on. I don't know who would help reload the ready-rack, but who it was would have a direct effect on what the tank could do during the replenishment time - if the gunner was helping, the main gun and coax MG would be temporarily disabled. If the TC, then spotting would be reduced. If the bow MG gunner. . . you get the idea.

The above would also be a factor when an AFV fires steadily for an extended period (for example, area firing into an enemy held town), empties it's ready rack and starts to fire directly from the floor lockers. Once again, my guess is that one crewmember would leave his post to help move ammo up to the loader.

I, for one still think that max. ROF for an AFV vs. an ATG, assuming basically the same gun, no supression on the ATG crew, etc., would be somewhat higher for the ATG. It was really cramped inside that sherman, and it just seems to me that this would slow the AFV loader down a bit compared to the ATG loader. a 76mm round, for example, is pretty long, and while it may not be overbearingly heavy, it's still going to be a bit cumbersome to handle inside that turret.

OTOH, I'm sure the loader in a WWII tank crew was trained pretty carefully on how to load the gun quickly and efficiently, so maybe they got to the point where the cramped quarters didn't effect them much. I don't know. Maybe the US Army had training standards for how fast ATG crews and Tanks crews should be able to fire - that would be a good way of verifying ROF differences between tanks and ATGs.

Another tricky thing to model - ATGs (and, indeed, AFAIK, all guns and mortars) usually do not keep all of their ammo right next to the gun for safety and space reasons (how would you like to share a foxhole with 50 artillery rounds??), so effectively an ATG has a 'ready rack' as well. when the ATG is unsupressed, this wouldn't have much effect, as "extra" crew members would be involved in shuttling ammo forward to the gun, but if the crew is taking fire, then I imagine that this transfer from the ammo storage pit to the gun pit would be much slower, reducing ROF once the ammo in the ATG's "ready rack" was expended.

Interesting subject. Thanks to JasonC and other knowledgable grogs who have posted comments here.

Cheers,

YD