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Mike D
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I know in general that tanks normally stopped to fire their main guns in WWII primarily because they lacked the sophisticated fire control systems of modern day tanks. And even though some of the later US tanks had a gun/turret stabilization system that was supposed to aid in such matters I don't recall that I've heard of tanks thusly equiped firing on the move either.

In any event, I ran across this in my reading as of late and found it to be quite interesting. It's a brief exchange between a Tiger commander and a senior German officer in the officer's mess after a training exercise in Mons Belgium in Apr. 1944.

"The senior officer who had observed the excercises asked one of the tank commander's to explain how it was possible to successfully engage targets while on the move. The seasoned commander this question was directed towards argued that the Tiger's (Tiger I) weight and its high speed made it unnecessary for a good gunner to stop in order to hit his target."

There are a number of things of note here. For one, it sounds like this was successfully demonstrated during the excercises???? It's kind of hard to tell since it doesn't go into any further detail on the matter. But why would the senior officer even ask such a question if something hadn't at least caught his attention during the exercise, if not having been actually demonstrated in full? Whether it was, or not, it is even more interesting to examine the tank commanders response. He primarily notes weight and "high" speed as the attributes that would make this possible. Now higher relative weight is understandable since it would serve to help stabilize the tank from the recoil of the gun and serve as a solid base from which to fire the gun while on the move pretty much just as it would as if it was sitting still even though the dynamics of the two cases are entirely different. The high speed part escapes me though. One would think that the slower the tank was moving the easier it would be for the gunner to hit a target while his tank was moving, not the other way around. In fact one would think w/ increasing speed that the tank would become less stable and start to bounce its occupants and the main gun around more making it more difficult to hit a target on the move w/ increasing speed. There's also the question of "leading" the target (or the reverse thereof in this case) since the firer is moving. If the target were more or less directly in front of the tank it would seem that the detrimental affects of the movement on targeting would be much less than trying to fire at a target off to the side. But again, increased speed would only make this more difficult, not less.

So my questions to the "brain-trust" (I use the term quite loosly smile.gif ) here at the CM board are as follows:

Has anyone else read/heard of accounts of tanks firing on the move and successfully hitting their targets in WWII, especially under actual combat conditions? This is one of the only references to such a thing that I can remember seeing so I'm curious what others know about it. I'm sure it was attempted from time to time depending on a given situation in combat, but I've always been led to believe that it was pretty much ineffective in terms of scoring hits consistently.

Would anyone like to take a stab at the "high" speed issue? I can't figure that one out at all.

Oh, and for those that are wondering the names of the two gentlemen involved in this exchange were none other than GeneralOberst Heinz Guderien and Knight's Cross w/ Oak Leaves holder and company commander Michael Wittman.

Mike D.

Aka Mikester

[This message has been edited by Mike D (edited 09-21-99).]

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And now that I've somewhat purposely led you astray in more ways than one in my first post, I'll share the following report w/ you which at least seems to indicate that firing on the move was achievable to some degree:

"SS Ober sturmfuhrer Wittman was in cover with his Tiger, separated from his company, when suddenly an English armored battalion, followed by an armored troop carrier battalion, was reported. After quickly issuing additional orders to his company, he drove into the English column, firing on the move. From 80m. Wittman first destroyed four Sherman tanks. He then positioned himself beside the column and roared along it, firing in his direction of travel. In this way he destroyed 15 heavy tanks in a very short time. Six were damaged and their crews forced to bail out. Subsequently, the escorting armored troop carrier battalion was almost completely wiped out. Wittman's Tiger was then hit by a heavy AT gun and he and his crew were forced to bail out. They proceeded to march 15km to a neighboring panzer unit (Panzer Lehr) and returned some time later to the scene of the fight w/ 15 PzKw IV tanks. Meanwhile they radioed back to their own unit and another Tiger company also moved in to join the fray…."

When all was said and done that day, June 13, 1944, Wittman had raised is total kills during the war to 138 enemy tanks and 132 enemy AT guns and he and his crew had single handedly stunted a major allied thrust out of Normandy in the area to the west of Caen in a little known village named Villers-Bocage. For his heroic action he received the addition of the Swords to his Knights Cross.

Mike D.

Aka Mikester

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<BLOCKQUOTE>quote:</font><HR>Would anyone like to take a stab at the "high" speed issue? I can't figure that one out at all.<HR></BLOCKQUOTE>

Mike,

Please bear with me Dynamics are not my favorite area. wink.gif I believe there are two major factors to consider to help you understand this statement. These factors are independent of the environment of your example so we can concentrate on these and not any "external" factors that may influence the problem (e.g. soft soil conditions)

The first is how suspension systems work. Without getting into some really technical stuff here let us suffice to say that suspension systems are very effective damping systems. They lessen the intensity of the vertical forces acting upon the vehicle. The slower the vertical force is applied to the vehicle the less the suspension "damps out". The easiest way to explain this is with an example. Warning you must first agree to not sue the author before reading on! Drive your car (SUV, Truck whatever) up to a speed bump slowly, say at crawling speed (preferably in a shopping mall parking lot while no one is there). Note how drastically the hood pitches as you climb and decend the speed bump. Now try it at say 25 mph. (if your vehicle can take it) You will notice that the car pitches up less than at the slower speed. The suspension system is now working and instead of the vehicle riding "up and over" the speed bump it more or less "takes it in stride".

The second factor is hidden in the above example. It is the invisble property of inertia (technically put...the resistance to rate of change of velocity). Inertia is a mass dependent property. Going back to the example above substitute the mass of a 60 ton tank for that of your 1.5 ton car. So a tank with it's MASSIVE amount of inertia is less affected by the bumps of the terrain.

I hope that helps, like I said there are other factors but these two are the most relavent.

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Rhet

[This message has been edited by Rhet (edited 09-22-99).]

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<BLOCKQUOTE>quote:</font><HR>he drove into the English column, firing on the move. From 80m. Wittman first destroyed four Sherman tanks. He then positioned himself beside the column and roared along it, firing in his direction of travel<HR></BLOCKQUOTE>

It's all in there... He drove into the english column , this indicates that a traverse adjustment was a minor adjustment if any at all. From 80m , at this range it is just point and shoot baby. Finally, firing in his direction of travel, they probably had the turret set to a fixed skew angle to the hull and just fired as the targets came into alignment.

Wittman was a tactical genius! He saw that he had the initiative and the element of surprise (along with the better equipment)and used it to legendary effectiveness. smile.gif

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Rhet

[This message has been edited by Rhet (edited 09-22-99).]

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Rhet, great response. I could not agree more. At higher speed the vertical forces of gravity and/or friction will start to be overcome by the inertia and momentum of the tank. To converse your speed bump example, think instead of driving your car across a large pothole. If approached slowly the car will sink into the hole. If approached at high speed the car will tend to sail across the hole with no perceivable dip in the chassis and body.

However, these explanations only address one axis, i.e. the vertical (y) axis. Higher speed would also tend to stabilize the horizontal (x) axis as well. This would be achieved mainly through the gyro motion of the traction system. All of those wheels and the track itself are spinning along an two parallel planes. The laws of physics say that they are reluctant to be moved off of those planes. The faster the spinning, the more reluctant -- that's why you can easily take your hands off the handle bars of a bicycle at high speed.

The tank therefore has angular as well as linear momentum working in its favor at higher speeds. This is important in Mike's second example because, as Rhet points out, Wittman has likely cocked his turret to the side, let's assume 30 degrees. He is traveling along the column and firing as each Sherman comes into the sight.

Just think about how much torque that 88mm gun is going to impart on the whole vehicle when it fires. Torque = force x length of the lever arm. On a Tiger, the gun is long and the force of the muzzle blast is high. So, if no other forces were acting on the tank, the firing of the gun would act to point the tank away from the target.

One of the forces keeping this from happening is friction -- i.e. the grip of the tracks on the ground. But, one liability of moving fast is that this friction is reduced. This happens for 2 reasons. First, kinetic (moving) friction is weaker than static (not moving) friction. This is a basic law of physics. The way you may have experienced this is when your car begins to skid. At any given point in their rotation, your tires are depending on static friction to hold the road. Once your car starts to skid, that static friction coefficient is lost. Consequently, once the car starts to skid, it is very likely to continue to skid because the linear momentum of the car overwhelms the puny force of kinetic friction your tires can provide.

Secondly, because the tank is bounding over at least somewhat unlevel terrain, chances are that the gun will be fired at a point when the tank has just cleared a rise or a dip has just fallen out from under the tank. In either case traction (aka the force of friction) will decrease. That is why the natural gyrostabilizing quality of the traction system becomes more important at high speed. It will tend to keep the tank on line.

I hope some of this helps. smile.gif

Pixman

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The enchanter may confuse the outcome, but the effort remains sublime.

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Having served on a tank I find the above account very believable considering the point blank range. No doubt the tank crew consisted of battle hardened veterans and the terrain, I'd be willing to bet, was smooth as silk. Mikeman

[This message has been edited by Mikeman (edited 09-23-99).]

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Pixman wrote:

"Just think about how much torque that 88mm gun is going to impart on the whole vehicle when it fires. Torque = force x length of the lever arm. On a Tiger, the gun is long and the force of the muzzle blast is high. So, if no other forces were acting on the tank, the firing of the gun would act to point the tank away from the target."

I think there needs to be a slight correction here. From the above you seem to be implying the length of the gun is the moment arm, when in actuality the moment arm would be more like the distance the turrent is offset from the C.G. of the tank. For example if you fire straight ahead no torque is generated (ignoring the verticle offset) since you are firing along the axis of the tank. Now if you rotate your turrent 90 deg in a tank like the T-34 where the turrent is located well ahead of the CG lets say 2 meters(don't have the actual numbers) then the torque=force x 2m. On a tank like the tiger it seems that the turrent is more or less at the CG therefore there isn't much of a moment arm and thus low torque.

All in all it would make for a really cool physics experiment. Maybe we can get Steve to strap a 88 to the weasel and do some high speed firing tests for us. We'll expect a report in the morning complete with quicktimes. On second thought you can do it after CM is out. smile.gif

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Guest Big Time Software

Hey, if anybody wants to give me an 88 I would gladly try. It will tear apart my Weasel for sure, but I can always get another one. The gun, on the other hand, would be a keeper wink.gif

BTW, I just saw a Sherman 75 KO a StugIV while on the move (fast) from about 350m. The turret was turned to about 2 o'clock in relation to its direction of travel. Lucky shot, especially because the 75 can only JUST barely kill the Stug from that distance.

Steve

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Rod, thanks for the clarification. Thinking through what you have said, it makes sense to me. There really is no lateral force being exerted on the gun barrel, so it cannot be part of the arm. The force of the blast is transferred directly along the length of the barrel, so the arm would indeed be defined by the distance from the base of the gun to center of gravity of the tank. Then the angle the gun is cocked to the side would determine how much of the force of the muzzle blast would be exerted along the vector perpendicular to the arm. Your example of pointing 90 degrees to the side would be the maximum torque point because the entire force of the blast would be on the perpendicular vector.

Forgive me guys, it has been 15 years since I opened a physics book in anger. But, as you can tell, I loved the subject! smile.gif

Now, how can we use this information?

With all that in mind, I bet Wittman was smart and experienced enough to figure out that his smoothest possible ride in this fire -on-the-go exercise was with his gun cocked to the side as little as possible. That's why I originally suggested 30 degrees. At 30 degrees roughly only a third of the blast force would contribute to the vector that would torque the vehicle. He may even have gone as low as 20 degrees depending on how close he was to the column. By doing this, the resultant vector of the force of the muzzle blast would fall primarily in line with the long (front to back) axis of his tank. This is by far the most stable direction from which such a vehicle can withstand a shock.

From a fire control standpoint, this approach would also give his gunner more time to sight each target and the crew more time to reload between shots. Fire accuracy would also be improved immensely because the gunner would not have to lead each target so much.

Steve's example of the Sherman firing with its turret at 2:00 chimes in with all of this.

So Steve, based on your example, it looks like "fire on the move" is in?

Pixman

aka Son of Diatribe wink.gif

------------------

The enchanter may confuse the outcome, but the effort remains sublime.

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Guest Big Time Software

Actually, tanks have always been able to fire on the move. They are just less likely to do so than when stopped. If the tank can't get a good bead on the target at 15mph (which is pretty fast on a battlefield) it isn't going to start slamming rounds out. But if it is going, thinks it has a decent chance, it will pop one off.

Steve

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Hey Pixman no problem, Its been about as long for me although I do delve into the world of physics occasionally at work. (When I'm not reading this dang message board smile.gif)

Thinking about it some more I guess the length of the barrel would have an impact but more on the force side of the equation, as an impulse so to speak. A longer barrel might distribute the force over a longer period and thus the maximum torque may be lower where a shorter barrel might just give one sharp whack and be over. So I guess we would need to integrate the equation over the period of.......ouch I hurt my brain. I need CM out NOW!

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Guest KwazyDog

Steve, I should be able to get your an 88 pretty damn soon, hehe wink.gif Will be interesting to see what they can do.

Hmm, the weasel isnt on the Vehicle List, but maybe it should be, Im sure you could find a great texture for it smile.gif

[This message has been edited by KwazyDog (edited 09-23-99).]

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