Accuracy While Firing On the Move (OR FAST) in CMBO

[edgars]

Does Jentz's book mentions over what terrain tests was executed?

(title of the book somehow suggests me that it was a desert )

But seriously, isn't the terrain the key factor in this subject?

[Slapdragon]

Sure, but it is the base from which CM extrapolates the rest of the figures.

[edgars]

So, it would seem only logical that a tank driving on the paved road has a higher chance to hit the target than a tank driving off-road?

[Slapdragon]

Unless the desert data was past a "tipping point" or place were accuracy cannot get better because it was down on the far side of the curve, telescoping terrains into one lump, that would be correct. For example, in a single situation, a tank on a road may get 35% to hit, on open terrain 31%, woods 21% etc. Road and open can be right on top of each othert.

In addition, tanks drive at progressively slower speeds in less level terrain. A Hellcat which moves at 35mph on a road only goes 23 on flat open and 16 in light woods. A Sherman goes 18, 13, and 9 mph (converted to English for the metric impaired and thus approximates). Slower speed means better acuuracy except as stated by Steve that there is a point were faster is better for "smoothing" the ride".

[aka_tom_w]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Big Time Software:

Folks,

Charles got back to me and reported this:

While this is not an exact match to situations we have been describing above, I think it does show that the accuracy for this small calibre gun was better than one would expect.

Steve<HR></BLOCKQUOTE>

WOW!

All I can say is Holy Crap!!

I'm blown away by that degree of accuracy on the move at 650 m!! And on the FAST move at that. (but it was a Small sample)

I would have never believed there were actual real world tests indicating that kind of accuracy while on the move in the Real WWII.

I'm not entirely convinced that the extrapolation from that small Data sample to all the tanks and all the weapons in the game is an apropriate projection, (if in fact that data was extrapolated to all weapons and all vehicels) BUT it is MORE real than all of our collective gut (non-RW tank gunery , ie. no real world experience for some of us) "feelings" put together, so at least we now know it is based on facts and real test fire data.

I'm sort of surprised no one else from this thread who is reading this forum, who has that book, has quoted or commented on that data yet? Any other comments from that book? At least we have a real reference and a verifiable source for the test now.

Thanks Steve! Thanks again Charles!

-tom w

[aka_tom_w]

<BLOCKQUOTE>quote:</font><HR>Originally posted by ciks:

So, it would seem only logical that a tank driving on the paved road has a higher chance to hit the target than a tank driving off-road?<HR></BLOCKQUOTE>

With respect to tanks firing on the move, I would agree that would be logical and so it would seem that a tank attempting to drive fast through scattered trees would be even less accurate, and a paved road would be more accurate than a dirt road and dirt road should be more accurate than open grass.

I imagine that is a heck of ALOT to ask of CMBB though.

-tom w

[edgars]

The Combat Mission doesn't factor in the terrain tank is riding over when calculating hit% of moving tank. Only speed and distance counts.

Take a look at my lilttle test here:

Tank - M4, target - PziV, distance 665-670m. M4 started behind a patch of woods and I checked the % at the start of second turn when M4 had achieved its full speed in the given terrain and came out from behind the woods (hence the distance varies a little).

Terrain Hit%

Road (both) 7%

Open 15%

Wheat 15%

Brush 17%

Scattered tr. 23%

So what can we learn here? If you want to fire on the move, do it from scattered trees! :eek:

(off course test was done under "lab conditions", if PzIV have had any ammo it would be easier to hit a slower moving tank in the treees rather than fast one on the road)

NOTE: When measuring hit% from wheat, brush and trees, M4 was on the very edge of particular terrain.

[ 07-31-2001: Message edited by: ciks ]

[Spook]

Given that Lorrin's (rexford) separate topic on "firing on the move" has slipped off without added discussion, I am posting his comments here:

<BLOCKQUOTE>quote:</font><HR> The ability to hit a target from a moving tank can be explained very simply.

Say a Panther is moving towards a sitting T34 at 500m, the 75L70 is aimed at a 500m range and the gun is set against target center. If the gun elevates 0.15 above the range setting between aim and firing, due to a bump in the ground, a change in slope or a vibration in the running gear, the trajectory goes 1.3m over the aim point, and misses the T34.

500m x tangent (0.15°) = 1.3m higher trajectory for a given distance

Fields generally have some slope changes, roads may have extremely small dips or grade variations, tank suspensions may generate some angular rotation of the front hull

relative to the rear.

It does not take alot of angular change to cause 500m shots to miss. <HR></BLOCKQUOTE>

Considering how physically miniscule that 0.15 degrees are, his comments are an interesting reference. It is therefore reasonable to infer that ANY moving fire at ranges beyond 500 meters would've been extremely improbable for a hit chance.

While the explanation is simple, though, the technical translation isn't necessarily so. If one wants to translate how uneven ground, suspension, etc. may change the gun's ultimate firing angle, one MIGHT have to take to defining "nodal points" between the ground and the gun support, with stiffnesses and dampeners defined for the nodal connections.

For example, take a large, heavy tank like the German Mk V Panther operating over muddy ground. Between the wheelbase, center of gravity, and vehicle weight (45 tons?), the inclination of the Panther might be more to "cut into" the uneven ground instead of being significantly "rocked" by it. The Panther's suspension might also help to "dampen" the ground unevenness even further. But of course, it's all dependent on situation and environment.

On a side note, therein was the main POTENTIAL benefit of the gyrostabilizer; it still depended the most on gunner proficiency for a 1st-hit chance rather than on the stabilizer itself, but the stabilizer's ability to "dampen" external factors to gun angle excursion to a moving vehicle could be measureable. As before, it also depended on situation and environment.

[ 07-31-2001: Message edited by: Spook ]

[Andrew H.]

The .15 degree change between aiming and firing is interesting, but I think that there are a couple of factors that would make it possible to hit beyond 500m.

The first point is that there is a very short time period between aiming and firing: the gunner is aiming and the gunner is firing. So the "bump" would have to occur between when the gunner pulls the trigger and when the trigger causes the shell to fire. This delay will be a fraction of a second, even if we include the additional delay between the gunner's brain and the gunner's trigger finger.

A second factor would the gunner's ability to anticipate terrain and adjust fire accordingly -- the gunner might wait until the tank has reached what appears to be the top of a bump before firing. Or the gunner may not fire until the tank reaches what appears to be a level patch of ground, or an even slope.

Assuming that the driver knows that the tank will be firing on the move (and the driver would know this), the driver may also seek out smoother areas of ground to drive over, to the extent that this is not incompatible with other orders he may have received.

[Spook]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Andrew Hedges:

The .15 degree change between aiming and firing is interesting, but I think that there are a couple of factors that would make it possible to hit beyond 500m.

The first point is that there is a very short time period between aiming and firing: the gunner is aiming and the gunner is firing. So the "bump" would have to occur between when the gunner pulls the trigger and when the trigger causes the shell to fire. This delay will be a fraction of a second, even if we include the additional delay between the gunner's brain and the gunner's trigger finger.<HR></BLOCKQUOTE>

Indeed, for a proficient gunner, the instant between "getting the bead" and pulling the trigger would be minimal. But the bigger issue to allow is that if the ground (or the tank's response to the ground) is uneven, then the ability of the gunner to put the crosshairs on a target is more challenging, especially for a nonstabilized gun. Under such a circumstance of moving fire, gunner proficiency should play its role to hit chance, but even for an experienced gunner, firing rate would've likely been reduced a good deal, given the added time likely needed to get a target into the crosshairs. Is firing rate reduced for a moving vehicle in CM?

<BLOCKQUOTE>quote:</font><HR>A second factor would the gunner's ability to anticipate terrain and adjust fire accordingly -- the gunner might wait until the tank has reached what appears to be the top of a bump before firing. Or the gunner may not fire until the tank reaches what appears to be a level patch of ground, or an even slope.<HR></BLOCKQUOTE>

Possible. But when a gunner starts trying to sight onto a target, it becomes more a case of tunnel vision. He might be able to "anticipate the ground" more if the gun & sight are facing in the direction that the tank is moving in. It would be more difficult to anticipate the ground if firing in the direction of the tank's left, right, or rear.

<BLOCKQUOTE>quote:</font><HR>Assuming that the driver knows that the tank will be firing on the move (and the driver would know this), the driver may also seek out smoother areas of ground to drive over, to the extent that this is not incompatible with other orders he may have received.<HR></BLOCKQUOTE>

Also a possibility. But on some occasions, the ground just may not be accomodating, try as the driver may in finding such ground. (He probably would also pay as much attention, if not more, as to which cover or defilade he can move the tank to if the tank comes under fire.)

[ 07-31-2001: Message edited by: Spook ]

[gredeker]

I was thinking about the physics of a tank firing while moving over uneven ground, and had the following idea, which is at least partially supported by Jentz's data (14% accuracy when moving toward the target from 900 to 600 yards, 33% accuracy when moving perpendicular at 650 yards [albeit at higher speed]): Tanks moving at speed may be more accurate when firing perpendicular to their direction of movement.

Assuming that the majority of a tank's motion while moving at high speed consists of forward/backward rocking, the greatest motion of the gun would occur when firing in the same direction of motion. Conversely, the angular rotation of the gun would be minimized when firing at a right angle to the direction of vehicle motion, thus (theoretically) minimizing the effect of vehicle motion on firing accuracy. Of course this would depend on the suspension and the relationship between the gun's location and the center of vehicle mass, but (at least in my uninformed mind) the motion affecting the gun would be less than firing forward. Thoughts, comments?

[ 07-31-2001: Message edited by: redeker ]

[Spook]

<BLOCKQUOTE>quote:</font><HR>Originally posted by redeker:

Assuming that the majority of a tank's motion while moving at high speed consists of forward/backward rocking, the greatest motion of the gun would occur when firing in the same direction of motion. Conversely, the angular rotation of the gun would be minimized when firing at a right angle to the direction of vehicle motion, thus (theoretically) minimizing the effect of vehicle motion on firing accuracy. Of course this would depend on the suspension and the relationship between the gun's location and the center of vehicle mass, but (at least in my uninformed mind) the motion affecting the gun would be less than firing forward. Thoughts, comments?

<HR></BLOCKQUOTE>

It's as you say, it depends on the location of the "axis of rotation" of a tank, moving over rolling ground, as compared with the gun axis. I anticipate that in most cases, the center of rotation would be lower down within the tank's hull.

[Battlefront.com]

Andrew wrote:

<BLOCKQUOTE>quote:</font><HR> So the "bump" would have to occur between when the gunner pulls the trigger and when the trigger causes the shell to fire.<HR></BLOCKQUOTE>

Not quite. The "bump" would have to occur between when the gunner pulls the trigger and the round leaves the end of the barrel. It is therefore possible that a shorter barreled gun (like the US 37mm) would be less affected by bumping than a longer gun (like a Panther's 75) all else being equal. Obviously muzzle velocity is a key factor here, as that determines the exit speed.

The other factor here with gun length is how far off the barrel is moved from aim point by a particular amount of motion. I am not very good with the actual math, but the concept is rather simple. If two vehicles are tipped at small angle, the one with the shorter barrel will be less off target than the one with the longer barrel.

Does this have a practical difference in real world accuracy when on the move? I think so. Is it modeled in CM? No. But it could explain why the British data appears to fly in the face of conventional wisdom in some ways.

Steve

[Durruti]

Hi Steve,

Your tests seem to have put *most* of the objections about firing on the move to rest but I wondered about your opinion on the earlier posts that included references to crews with gyro-equipped tanks finding them so 'unreliable' that they de-activated them? I'm sure I've read this in a couple of sources myself but I'll have to 'put my hands on them' as they say Does Hunicutt have anything to say about reliability or malfunctions?

Cheers,

Durruti

[Spook]

Repeating an earlier subtle query, Steve, does a vehicle's moving status have an affect on firing rate? If not, do you think it should?

I pose this question on the generalized view that yes, a moving vehicle should have some lowered level of firing rate, regardless of crew proficiency.

[Battlefront.com]

Spook,

I don't believe that it does, but I know it is something we were kicking around the other day. I'll see if there is something that can be done about this.

Durruti,

We have discussed the gyro thing to death in previous posts, which is why you didn't see me talking about it much Basically, there is evidence that some crews turned it off because either they were not trained well enough and/or the device was malfunctioning. How many did this... we have NO idea. However, a complicating factor is that the earlier gyros, prior to CMBO's timeframe, were prone to malfunction and the devices were relatively new to the crews using them. From the little information that is out there we gathered that much of the negative statements made about the gyros were being pointed at the earlier ones, not the models found in CMBO's timeframe. Unfortunately, the way CM is coded we can't "disable" an individual feature on the fly.

Steve

[Slapdragon]

Oddly enough on the subject of Gyros. The biggest direction we hear of gyros from is Ed Greenwood, who based his data for not modeling gryos on:

1) the fact that the game engine he was using did not easily model shooting on the fly.

2) The first Gyros used, expecially in the M3, were buggy. Turns out they were buggy because they were top secret, and only certified and classified techs could open the gyro case, so they got very little preventative mantinence. By 1944 most tank crews were experienced enough with gyros to set them properly and unit work shops had mostly ignored the rules about not opening them up (in the book "Hit Hard" the 761st starting opening and fixing their own gyros in 1943 despite warnings not to do so and went ashore in Europe with all attached and functioning.)

So the saying that no one used gyros was more gamer urban legend caused by Greenwood deciding to throw them out than anything else.

[Username]

I take it the vehicles are moving over flat, sandy conditions? These conditions are almost ideal then. The flat terrain being an obvious benefit and the soft ground acting as a vibration damper. Ive driven tracked vehicles over mud, grass, roads, sand etc. It makes a big difference.

Also:

'These numbers are higher than you might have expected. The 2pdr was fired from the gunner's shoulder (!) and had no gyrostabilizer. So I think the gyro-equipped Stuart, firing at shorter range in your example (about 580 yds on average) compared to this one (about 700 yards on average), ought to be able to do even better.'

Believe it or not, the human being is a servo system. He can see the problem and corrects for it on the fly. The fact that the gun is resting on his shoulder (and some other point of course) does not make it +BAD+. A ~gyrostabilizer~ is an open loop correction device mostly. It will always be 'behind the ball' in correction. I would argue that a fixed gun, gyro or not, would be #worse# than these results under most conditions.

But what do I ?know?

Lewis

[Username]

I hate to break this to you <grogs> but moving on a hard road is [NOT] the best conditions at any speed!! I firmly believe that grogilians are couch commanders.

In WWII there were two practical tank speeds in combat. ~Crawling~ and *full tilt boogying*.

lewis

[Username]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Big Time Software:

Not quite. The "bump" would have to occur between when the gunner pulls the trigger and the round leaves the end of the barrel. It is therefore possible that a shorter barreled gun (like the US 37mm) would be less affected by bumping than a longer gun (like a Panther's 75) all else being equal. Obviously muzzle velocity is a key factor here, as that determines the exit speed.

Steve<HR></BLOCKQUOTE>

Steve

Since I am on double-secret, defcon 4 level, probation, I am going to try to control myself. But you did call a bunch of people here physics ninnys (or something like that) earlier in this same thread. So I am going to read you the riot act a little.

Whats easier to swing? A small baseball bat or a long heavy one? Which has more resistance to a change in motion? Its the long one. Inertia.

But theres something even more basic going on. Related rates. The time between the primer igniting and the round leaving the barrel is very small. Something like 11 or 12 uSecs roughly. The barrel, even if already moving at a fast angular rate, would not move much during such a short period of time! The round moving down the barrel would add mass further down the length of the barrel anyway making the barrel less resistant to a change of position also! Ive felt this when trying to slew an MG while firing. Theres also the spinning round resisting a change like a gyro too!!!

Lewis

[Battlefront.com]

Lewis,

<BLOCKQUOTE>quote:</font><HR>Since I am on double-secret, defcon 4 level, probation, I am going to try to control myself.<HR></BLOCKQUOTE>

See, it wasn't so hard to respond to my post like a rational humanbeing interested in discussion and not flaming, was it?

<BLOCKQUOTE>quote:</font><HR>But you did call a bunch of people here physics ninnys (or something like that) earlier in this same thread.<HR></BLOCKQUOTE>

Obviously I was joking. If physics were so easy we'd all be getting nominated for Nobel Prizes.

<BLOCKQUOTE>quote:</font><HR>The barrel, even if already moving at a fast angular rate, would not move much during such a short period of time!<HR></BLOCKQUOTE>

OK, I was wondering about this. So although there is a technical difference, there is no practical difference? Sounds reasonable.

Well, we have both learned something then, haven't we? I've learned a little bit more about physics, and you have learned that you can engage in a discussion (and prove a point) without being a jerk

BTW, yes... if the British tests were done on flat desert hardpack (this is our assumption), then the test is "ideal". If you note Treeburst's Stuart test "matches" the British test, but at about 150-200m shorter range. Meaning, the British test data was not taken as gospel, but rather an example to learn from.

Steve

[Stephen Smith]

I would guess everybody is getting tired of this discussion, but I would have to say that the book reference quoted by Charles and Steve don't put the argument to rest-in fact, it doesn't even address the argument. I mentioned quite a while ago that modern tanks on firing ranges fire while 'on the move' but 'on the move' really means driving about 15 mph along a gravel road-a unique and unnaturally flat surface. This is not what is intended by firing 'on the move' in CM, and it is not what is modelled (unless the moving tank happens to be moving along a flat section of a road!). The quote in the book simply verifies what I and others have said all along-that you CAN hit when you are going very slowly on unnnaturally flat surfaces (as another comparison, modern M1's moving slightly off-center from the target should expect 90% accuracy at targets 1600 meters away! modern tanker's scores on tests- 'tank tables'- depend on better than 90% accuracy). I still find it hard to believe that anyone could hit while driving much faster than that, on any rough terrain (and by rough, I mean any natural field, ANY alteration in terrain, which would include everything except gravel roads, paved roads, and possibly-only possibly- dry farmer's fields).

I think it would be hard to hit when moving faster for two reasons-one was mentioned above-every little alteration in the ground will cause the gun to move up and down (even as little as 1.5 degrees, I think, from the mentioned example), but also, because the gunner will have a tough time both staying steady enough to look through the site, and will have a tough time keeping oriented with the site while moving (try to run while looking through a toilet paper tube, looking at a car down the street. Once you shake and are no longer 'aimed' at the car, try to figure out what direction to move it to correct back to the car).

So, if the book quote is the 'source' for firing on the move statistics, then I believe that information was misapplied. All the book says (which is what skeptics have been saying all along) is that on an artificially flat surface, on a firing range, at slow speeds, it is possible to hit a target while moving.

One group I would like to hear from are any Bradley gunners? The bradley has a 20mm 'gun' (practically a really big machine gun) that is very light and nimble, and turret mounted with a sight. We have heard from several M1 tank gunners, who are skeptical. But I wonder if the Bradley's smaller, quicker rotating turret IS more 'aimable' on the move-that would suggest that perhaps early war tanks, with small nimble guns and turrets, may be more aimable as well.

steve

[Tero]

The British were big on firing on the move before the war. The gunner acted as the stabilizer in their tanks. But alas that worked only for the professional tankers with years of experience. Once the fresh conscripts started manning the tanks that doctrine was proven less than ideal so they had to revert to stopping to shoot.

I assume the test mentioned was done on a stationary target which is not shooting back at you with a tank that had its gun in a "free swing" mount with the expert gunner standing on the floor and using his body as the shock absorber-cum-aiming apparatus (like they were in the early the cruisers).

Also, while faster moving tank could be more accurate on the test there is nothing said about the reload cycles and ROF and how they are affected by the "less bumpy" speeds. IIRC only the modern Soviet/Russian MBT models have mechanical loaders, the rest use humans. The tanks used humans during WWII. I think the 37mm gun on the M5/Stuarts was a single shot weapon as was the 2 pounder. Reportedly one of the reasons the mechanical stabilizer was disconnected was because it made reloading harder.

How do the British test results correlate to the accuracy of mechanically stabilized guns fired on the move, if the test was done with a mount that was not mechanically stabilized and was not mechanically operated (handwheels used to lay the gun) ?

Furthermore, there is no elements in the CM modelling now that account for breakdowns and/or malfunctions of the mechanical stabilizer. Where they 100% reliable ?

On aiming and shooting on the move:

one thing not being induced into the equation is multi-axis "bumps" that tilt the tank both horizontally and vertically. These kinds of bumps would make reacquisition of a target really hard and time consuming (in the battle field scale).

[ 08-01-2001: Message edited by: tero ]

[Spook]

Responding to a earlier comment from Stephen Smith:

I think it would be hard to hit when moving faster for two reasons-one was mentioned above-every little alteration in the ground will cause the gun to move up and down (even as little as 1.5 degrees, I think, from the mentioned example), but also, because the gunner will have a tough time both staying steady enough to look through the site, and will have a tough time keeping oriented with the site while moving (try to run while looking through a toilet paper tube, looking at a car down the street. Once you shake and are no longer 'aimed' at the car, try to figure out what direction to move it to correct back to the car).

The cited example, from rexford, actually was one-tenth of that (0.15 degrees). But all else of what you are saying above correlates to my earlier point, in that a trying to aim a gun within a moving vehicle in WW2 likely took more time to get the target "lined up."

[aka_tom_w]

I'm still reading this thread with GREAT interest.

Lets all try to focus (just a suggestion here ) on how we can help Steve and Charles model shooting on the move better in CMBB.

What where the important technical considerations on the Eastern Front?

Which vehicles from which Side fired on the move?

How accurate were they?

What was the SOP for firing on the move?

Who?

When?

Where?

I think it is clear that we will not be getting any more updates or patches to CMBO so with that in mind the purpose of this thread was to bring this issue of accuracy while firing on the move to the attention of Steve and Charles so we can research how to make this aspect of the game, ( oops, WWII military combat simulator) MORE realistic on the Eastern Front.

I hope everyone else has found this thread has informative has I have!

Thanks to ALL the experienced gunners who have posted here with their Real Life fire on the move experience.

-tom w