Max Hit Probability

[rexford]

German data on HE "beaten zone", area where 50% of HE shots will land if range to a ground target is perfectly estimated, clearly shows that low velocity HE is more accurate than high velocity HE.

This is not my speculation, it is a fact.

Flat trajectories are impacted more by random scatter than curved trajectories when it comes to landing on the ground.

It is not the easiest thing to grasp but it is so.

This is why low velocity guns are better at putting accurate fire down on a ground point than high velocity.

Make a drawing of a straight-line shot from a tank gun barrel to a given ground point and then the same tank shot with a curved trajectory, and then lift both trajectories the same amount vertically, but a small increase. The straight-line trajectory moves further away than the curved trajectory. Is so?

[rexford]

Please also note that the preceding post did not mention that low speed HE rounds generally pack alot more TNT than higher velocity HE (U.S. 76mm HE vs 75mm HE), so lower velocity is not only more accurate but generates more casualties.

A ground target can be a bunch of infantry standing in the open, crouching, lying, running, sitting against a tree, etc. Or hiding and shooting from narrow slit trenches on level ground.

This is a ground target.

If infantry is behind a 3' high stone fence and you want to blow them away from 750m range, is the higher velocity HE accuracy sufficient to hit the fence or is a nice arching 75L24 shot the answer> Depends.

If it is windy 75L24 HE first shot will be blown astray more than 75L70 HE, but this is easy to correct for on second shot if major gusts are not an issue.

Hitting ground points with HE seems to favor close support guns like 75L24, hitting vertical targets may favor 75L70 HE.

HE beaten zone is calculated by Germans and makes sense, low velocity HE has less scatter on ground (in long direction) than higher velocity. This is why short howitzer like guns used on tanks, and why the very low muzzle velocities with British 3" and 95mm close support guns were okay in field.

[Jeff Duquette]

A figure to kind of compliment Rexford’s above postings. Assuming the same vertical probable error you can see how as angle of fall decreases (high velocity rounds), horizontal probable error increases. As angle of fall increases (low velocity rounds…again assuming same vertical probable error) horizontal probable error decreases.

[Jarmo]

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

Flat trajectories are impacted more by random scatter than curved trajectories when it comes to landing on the ground.

It is not the easiest thing to grasp but it is so.

<HR></BLOCKQUOTE>

Hell I knew it was worth it to follow this thread!

A real eye opener. It's all so simple now.

[ASL Veteran]

I guess we can now surmise that the basic 75mm Sherman may have a greater chance of hitting an infantry target than an armored target?

I also gather that when firing at an armored target, a 75L24 would be less accurate than a 75L70 initially, but that the increase in accuracy from bracketing would be more dramatic? Taking this to the comparison with the 88 Flak, the 88s first shot accuracy would be much higher than the 75L24 at ... say 700 meters, but after three or four bracketing shots, the 75L24 would match the 88s accuracy at that range so that the increase in accuracy between bracketing shots would be higher with the 75L24.

With an infantry target, the lower the velocity the better, so that the 75L24 would have a higher initial accuracy than the 88, and that the 75L24 would remain more accurate throughout. Of course, the 88s HE round would probably be lighter and fired at a lower velocity than its AP round, so how much accuracy would be lost?

This may be a good place to tie in Germanboys comment about the use of fused shells for the 88 Flak. Maybe it would be easier for the crew of the 88 Flak to fire a fused shell that would burst when arriving at the target rather than an HE shell that needs to impact the ground where the infantry were located? If the 88s HE round were of a high enough velocity it may be inaccurate because of it. Just a thought ....unfortunately, I don't believe that there is any way to test the accuracy of HE vs infantry in CM between the various guns because you don't get a 'to hit' percentage with the target line - only exposure.

[:USERNAME:]

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

Please also note that the preceding post did not mention that low speed HE rounds generally pack alot more TNT than higher velocity HE (U.S. 76mm HE vs 75mm HE), so lower velocity is not only more accurate but generates more casualties.

Hitting ground points with HE seems to favor close support guns like 75L24, hitting vertical targets may favor 75L70 HE.

.<HR></BLOCKQUOTE>

More clutter from Rex.

German 75mm tank weapons all fired the same HE with different cartridges crimped on them. look it up. In fact; do a search here. Nice try though. I admire knee jerk arguments.

I think you mentioned a range of 750 meters in your post. Do you really think the shallow angles that a 75mmL24 and a 75mmL70 would have at that range, are that different that your argument is valid? That it could possibly out weigh having a high velocity weapon?

Why not mount mortars in tanks?

[Guest Big Time Software]

Just a few things I want to clarify.

1. CM does model subsequent shots having a higher accuracy than earlier ones (up to a point). However, we model this in a somewhat simplified manner and don't do a strict simulation of bracketing per se (though the results are similar).

2. We do not use a "to-hit probability table" in any way, shape or form. The core basis of our to-hit equations is a Gaussian function. It has a "bell" shape very similar to the accuracy curves that people have posted in this thread.

3. Let's not use M1A1 Abrams gunnery as a yardstick for what we should expect from WW2 gunnery.

Having said that, I'll take a look at the long-range figures and perhaps "up" our Gaussian curve at the long range end.

Our method is fundamentally sound but we could have a weight or a coefficient off by a bit. I'll see if it needs a tweak.

Charles

[aka_tom_w]

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

Just a few things I want to clarify.

1. CM does model subsequent shots having a higher accuracy than earlier ones (up to a point). However, we model this in a somewhat simplified manner and don't do a strict simulation of bracketing per se (though the results are similar).

2. We do not use a "to-hit probability table" in any way, shape or form. The core basis of our to-hit equations is a Gaussian function. It has a "bell" shape very similar to the accuracy curves that people have posted in this thread.

3. Let's not use M1A1 Abrams gunnery as a yardstick for what we should expect from WW2 gunnery.

Having said that, I'll take a look at the long-range figures and perhaps "up" our Gaussian curve at the long range end.

Our method is fundamentally sound but we could have a weight or a coefficient off by a bit. I'll see if it needs a tweak.

Charles

<HR></BLOCKQUOTE>

WOW

I think thats worth repeating

"Having said that, I'll take a look at the long-range figures and perhaps "up" our Gaussian curve at the long range end."

Who said the magic words in this thread that got that reply above from Charles?

Long range accuracy now maybe more accurate?

That's a big deal

The accuracy in the game under 500 meters is now a little higher as well so it would seem.

-tom w

[rexford]

Please note that I compared U.S. 76 HE to 75 HE, and spoke in general terms, did not specifically address German 75L70 and 75L24.

Knee jerk reaction, gross oversimplification?

Can't see any from this angle.

We will try to verify that 75L24 HE was not more potent than 75L70. Any one have any data on this?

If 10% max on Nashorn hit probability at 2000m is true, this should be looked at first.

My system uses range estimation error spread and applies to trajectory, with dispersion, and computes hit probability. If average error is 25%, o% errors occur and 75% errors, too. What is a gaussian bell shaped curve for accuracy?

Range estimation errors follow a bell shaped curve, standard deviation about equal to average range est. error, and this data is then fed into trajectory analysis. But one has to get the trajectory analysis right for the system to work.

Nashorn without range finder should get more than 10% hit probability at 2000m after several shots at same stationary target.

[rexford]

Tanks carrying mortars? Didn't some do this?

The question is valid though easily answered.

Mortars are good against "ground targets" but what about bunker openings, and buildings, and walls, and any number of vertical targets.

We're searching for HE weight in 75L24 and 75L70 HE, and will shortly have answer. Based on what I remember, 75L24 had more TNT than higher velocity HE from other German 75mm guns. Based on what appears to be the fact, higher velocity HE needs thicker walls than lower muzzle speed, so less TNT. This seems to be general rule.

Exceptions to rule may exist. An earlier post stated that miniscule HE shell fired by 17 pounder was beefed up with TNT by lowering the muzzle velocity. Consistent with general rule.

Everything in my posts is thought out and checked against multiple sources, has been reviewed with other members of the group and can be supported if someone wishes to ask for more back-up. Sometimes the statements are a bit short and sound simplistic, but the back-up is there.

Just ask if you are interested, and I'll provide whatever is needed. We don't know everything but what we state has usually been subjected to all sorts of review over the last 20 years. We're always cross-checking our stuff when something new pops up.

I work with Robert Livingston, and we were one of the first, if not the first, to identify the specific manner in which slope effects for steel projectiles are a function of T/D, that U.S. armor was flawed prior to 10/43, that the Panther glacis was flawed alot (but not always, and the front nose was hardly ever bad), we defined shatter gap in terms of specific factors, defined just how better U.S. 75mm HE is than 76mm HE in terms of casualty potential (it's not the total weight of shrapnel, it's the number of pieces and their velocity), etc.

I do the math, mostly statistical studies and curves of best fit, and ballistic/trajectory stuff. When our armor booklet comes out it will be the ultimate in compiled consistent data.

Sound like knee jerk reactions and fuzzy logick?

[Guest Big Time Software]

rexford,

I think it would help people to read your posts if you made it clear what they're in reference to. It can help to "quote" the text of the person you're responding to, if any. You can go that by clicking on the little "reply" icon above the person's post and then editing as necessary. No offense intended by this - just FYI.

Charles

[rexford]

Thanks to Jeff Duquette for the excellent graohic that shows how low speed HE can be more accurate than higher velocity against ground point targets.

That makes Sherman 75 even more lethal compared to 76, slower velocity/mo' accuracy against ground point targets and more TNT, mo' pieces of shrapnel and mo' velocity on the pieces so they go through more and penetrate deeper. It ain't the total weight of shrapnel, it's the fragment total and velocity. A 155mm shell that breaks into two pieces is less of a danger than a 75mm that busts into 500!

[:USERNAME:]

I am going to do an experiment. I am going to shoot at paper vertical targets with a high velocity rifle and then I am going to turn the paper targets 90 degrees so they are flat and try to slice them with the same rifle. then I am going to chuck rocks skyward and when one comes crashing through the paper, I will prove rex right.

Then I will prove that 88L56 Tiger I tank guns arent good anti-aircraft weapons.

lewis

PS Jeffs post shows such an exaggerated angle. The angle difference is minimal between 75mmL70 and 75mmL24 at 750 meters. You seem to be focusing on what you call scatter. Its really the angular error from a weapons line of fire. You just like to disregard the short barreled weapons angle error? Which is more susceptible to this angle error? A long barrel or a short?

[This message has been edited by :USERNAME: (edited 01-21-2001).]

[rexford]

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

I am going to do an experiment. I am going to shoot at paper vertical targets with a high velocity rifle and then I am going to turn the paper targets 90 degrees so they are flat and try to slice them with the same rifle. then I am going to chuck rocks skyward and when one comes crashing through the paper, I will prove rex right.

Then I will prove that 88L56 Tiger I tank guns arent good anti-aircraft weapons.

lewis<HR></BLOCKQUOTE>

Sir,

We are putting forth data that is supported by WW II German ballistic analysis,and our own review. Previous discussion should provide enough for you to understand the concept.

One additional note. At 800m, German data predicts that 50% of 75mm L48 HE will fall within a 61m long distance when range estimation against a ground target is exact. (50% will be more than 30m away from target ground point). This is at 550 m/s muzzle velocity.

88L56 HE at 810 m/s has a much larger ground dispersal.

Descent angles and dispersion for WW II Tank guns at 800m does result in large "errors". We used 800m because 750m data was not available.

We can't argue with these figures, and would welcome analysis that shows them to be incorrect.

(note, BTS fixed the quoting above. Rexford, you need to end the "quote" using "/quote" in brackets)

[This message has been edited by Big Time Software (edited 01-21-2001).]

[rexford]

Lewis,

The concept that low velocity HE may be more accurate than faster rounds against ground point targets may not be an easy thing to accept, and some active tankers who were part of our group left when we pursued the theory ("velocity low is the way to go").

[LuckyStrike]

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

Just a few things I want to clarify.

2. We do not use a "to-hit probability table" in any way, shape or form. The core basis of our to-hit equations is a Gaussian function. It has a "bell" shape very similar to the accuracy curves that people have posted in this thread.

Charles

<HR></BLOCKQUOTE>

I assume when you say you are using a Gaussian bell shape you are just taking the right half of the bell, such that the maximum hit probability, which would be the mean (highest point) of the bell, occurs at the minimum range.

[This message has been edited by LuckyStrike (edited 01-22-2001).]

[aka_tom_w]

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

I assume, when you say you are using a Gaussian bell shape, you are only taking the right half of the bell shape? That is, the maximum hit probability, which would be the mean (highest point) of the bell, occurs at the minimum range.

Otherwise, a (complete) bell-shape accuracy curve makes no sense.

<HR></BLOCKQUOTE>

I hope Charles is refering to this "bell curve" in the lower half of this diagram?

Is that correct?

and like the half bell in this one:

I would be interested to see just one of these diagrams for one main weapon as modeled in cm.

Can we see the bell curve diagram cm uses for chance to hit accuracy to set up the allgorythms for the 88 mm main weapon in the Tiger 1?

just curious

-tom w

[This message has been edited by aka_tom_w (edited 01-22-2001).]

[This message has been edited by aka_tom_w (edited 01-22-2001).]

[:USERNAME:]

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

At 800m, German data predicts that 50% of 75mm L48 HE will fall within a 61m long distance when range estimation against a ground target is exact. (50% will be more than 30m away from target ground point). This is at 550 m/s muzzle velocity.

B]<HR></BLOCKQUOTE>

Now compare that to the velocity of the 75mmL24. I believe its 440M/s for the HE round.

Do you really think the angles are that different at 800 meters? Will you continue to post more apples and oranges data?

I reiterate. Your point is moot. 75mm armed tanks/assault guns arent meant to shoot at these "plastic soldier" target scenarios that manifest your mind. The soldiers would get to cover or just get lost.

Why not titilate us all with scenarios where the lay of the land falls off at exactly the same as the shell drops from guns? Certain terrain would be velocity hostile? Maybe avoiding parabolic valleys is a good tactic?

Did you know that shooting exactly at a monkey as it leaps off a cliff guarantees a hit? Fascinating but true!

By the way. I like the way you avoid answering questions. Its very reminiscent of Steve from BTS.

Lewis

[Guest Big Time Software]

Lewis wrote:

<BLOCKQUOTE>quote:</font><HR>By the way. I like the way you avoid answering questions. Its very reminiscent of Steve from BTS.<HR></BLOCKQUOTE>

By the way. I like the way you insist on being a jerk instead of trying to have a rational and respectfull discussion. Its very reminiscent of Lewis from nowhere.

Why don't you just stick to using your brains for discussion instead of the other bit of you that you show here so very often? People actually have respect for you when you do.

Steve

P.S. Lewis doesn't dodge questions. He just abuses people until everybody forgets what was really being discussed.

P.P.S. Someday Lewis, I will run out of tollerence for your behavior. Nobody understands why this hasn't happened already, and even I don't know why.

[This message has been edited by Big Time Software (edited 01-22-2001).]

[Matthew_Ridgeway]

Well-said BTS. I hope this means this thread will return to a reasonable discussion on accuracy now.

[This message has been edited by Matthew_Ridgeway (edited 01-22-2001).]

[Simon Fox]

Steve, that's because over time Lewis has developed a fine judgement of the limits of that tolerance. hehe

Also from time to time he manages to curb his natural inclination.

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Muddying the waters as usual.

[Bastables]

Bah! When they show clips on the news of our boys over in Timor post May, just be sure to be looking out for a frantic Kiwi soldier holding a sign reading "Username was wrong! He was wrong before and he's still wrong." And "PS CM rocks my world!"

If any Kiwi soldier states that their job in Timor is to sell the purple balloons, (to irritating press questions of "whats your job son") that will also be me.

[This message has been edited by Bastables (edited 01-22-2001).]

[:USERNAME:]

The thread is supposed to be about tank gun accuracy vs other vehicles.

I think that rexford is not only off topic but wrong. He claims to have data but insists I need to make a paradigm shift to his thinking and just accept his gospel.

I disagree and have a very good case with the german 75mm weapons.

Infantry in the open are not point targets. At the range we are discussing, 700-800 meters, they are not point targets for MGs either. I would not equate infantry standing to infantry in slit trenches BTW.

Lets see if rexford comes through. Specifically, whats the difference in angle between a 75mmL24 and 75mml48 and a 75mmL70 9all with HE) at 800 meters? Does it look remotely like the angle posted by Jeff? Do you have evidence that the german 75mm KWK weapons fired different HE shells? Why would the germans have a higher muzzle velocity for the L24 HE than the AP? Seems to contradict your point.

I can live with the typical reactions to my posts. Everyone knows that the real issue here is that the armies developed delayed action fuses to take advantage of the steep impact angles that we are discussing here. Thats right, I am talking skipping HE shells for this situation. An airburst with a 75mm HE, even if twice the distance than a ground burst, is much more desirable.

[Jeff Duquette]

<BLOCKQUOTE>quote:</font><HR>USER:

I think that rexford is not only off topic but wrong. He claims to have data but insists I need to make a paradigm shift to his thinking and just accept his gospel.<HR></BLOCKQUOTE>

I certainly have not come off with the impression that Rexford is presenting anything as gospel. I've seen the data. I have also taken the time to work through several examples of Rexford's trajectory equations and compared them to "real" data. As I had indicated before Rexford has employed regression to describe actual trajectory data. Correlation to actual data is excellent.

I will post a mimeographed copy of German test fire data this evening for say the 88L71 (pzgr. 39/43). His numbers and regression formula have all been presented on this and other threads (I have taken the time to present links on the previous pages of this thread if anyone is interested). The historical testing data is obtainable if you bother to take the time and research the subject. After I present the 88L71 data I would be curious to see you develop a model to predict its trajectory and probability of obtaining a hit on say a 1mx1m target at various ranges. I'll give you the dispersion data as well.

Regarding your reaction to my above posted figure for vertical and horizontal probable error… I'll be sure to let the US ARMY know that the next time they prepare a Field Manual discussing exterior ballistics they should consult with "Usurname" cause he thinks the figures are exaggerated.

[Iron Duke]

Damn California and its power crisis!!! I haven't been able to use my PC all weekend (and part of last week) and look how much I miss out!

<BLOCKQUOTE>quote:</font><HR>Jeff D wrote: The Coalition Army that went into the Gulf was basically an amalgamation of Green Panzer Truppen (some were probably even scientists ).<HR></BLOCKQUOTE>

Aaaah! No!! I would not call the VIIth corps a Green unit in any shape or form! Do you know how much we trained just prior to shipping out? Let me put it to you this way...of my first 2 years in the Army, over 60% of that time was spent in the field! This is about 30% more than normal even for a line unit in Germany.

I would imagine that the British units that deployed could not have been considered Green units either.

Hehe...oh well, it doesn't matter anyway...back to the subject.

<BLOCKQUOTE>quote:</font><HR>Charles wrote:3. Let's not use M1A1 Abrams gunnery as a yardstick for what we should expect from WW2 gunnery.<HR></BLOCKQUOTE>

You are correct of course and I will speak no more on it!

<BLOCKQUOTE>quote:</font><HR>Having said that, I'll take a look at the long-range figures and perhaps "up" our Gaussian curve at the long range end.<HR></BLOCKQUOTE>

Yes. Charles, you won't regret it, you once again prove to all concerned that BTS has an open enough mind to see constructive criticism in a positive light and perhaps improve the game for it. Bravo. I salute you.

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One shot...One Kill