Max Hit Probability

[LuckyStrike]

Given the current CM gunnery/ballistics model appears to be flawed, this thread certainly needs to be kept alive.

bump

[Jeff Duquette]

I can't think of anything else to add at the moment. For the lack of anything better to say here is some stuff From my old soldiers manual for M48A5 crewmen:

<BLOCKQUOTE>quote:</font><HR>Battlesight gunnery. Battlesight is a gunnery technique which can be used in most dangerous surprise situations. Battlesight gunner procedures start from a battlecarry posture. It is normally used when the fire control system is not fully operational or weather conditions (fog, rain) or enemy actions (use of smoke) prevent the TC from using the range finder. Although not as accurate as precision gunnery, battlesight gunnery is a quick technique to use. Battlesight gunnery is only accurate at battlesight ranges +/-200 meters. Battlesight gunnery takes advantage of the relatively flat trajectories of armor-defeating ammunition to ensure a respectable probability of first-round hits. Battlesight gunnery consists of a preloaded round in the gun and either a range preindexed in the range finder, or the gunner using a designated range line on one of the ballistic reticles In the M105D telescope. Point of aim will continue to be center of visible mass, as the gunner applies the rules of lay.

A battlesight fire command is a preplanned technique; the fire command format is standard. Since the system is already preindexed with ammunition and range, the ammunition/weapon or searchlight element is changed to the word "BATTLESIGHT" ("GUNNER—BATTLESIGHT—TANK—FIRE"). This informs the gunner that the target is within battlesight range, the battlesight ammunition will be fired, and there will be no attempt to determine range. The gunner will fire using the gunner's primary sight and preindexed range or a predetermined range line on the telescope reticle. The loader will continue to load the battlesight ammunition until the engagement is terminated.

<LI>Most likely target to be engaged. If the primary Threat is tanks, SABOT is the most appropriate ammunition. If the Threat is other than tanks, use HEAT-T.

<LI>Most likely size of target exposed. If the most likely size of the target to be exposed is 1.5 meters (5 feet) or higher (which is what a Threat tank will expose to engage you), the standard range for battlesight listed will give you a very good chance of a hit. Using the Firing Tables (FT)105-A-3, look at the maximum ordinate listed for the round you are using to make a determination on the range to use.

<LI>Range is a primary consideration when selecting a battlesight setting. The maximum setting a TC is authorized to use without platoon leader approval is 1,200 meters for SABOT and 900 meters for HEAT-T. If visibility is less than the above ranges due to terrain, weather, or smoke, the TC should use a range setting equal to the maximum visibility. For example: If the maximum visibility due to weather is only 820 meters, the TC will use 800 for a battlesight setting until the visibility changes. The key factor for the platoon leader to keep in mind is that as he extends battlesight range, he increases the chance of missing a target that is at a close range.

<HR></BLOCKQUOTE>

========================================

This is from the German Army WWII instruction booklet "Gunnery Training and Firing Exercises" (Schieftanleitung and Schulschiepubungen)

<BLOCKQUOTE>quote:</font><HR>In addition, to maintain a constant state of combat readiness a round must already be loaded in the cannon (with the safety switch on) and a range setting set on the sight that is pre-selected by the tank commander that depends on the situation and terrain. As a rule, an armor-piercing round is loaded and the range setting on the gunners sight is at either 800 or 1000 meters. All of the other weapons — the turret, bow and air-defense machine guns — are also loaded.<HR></BLOCKQUOTE>

You reckon it was merely a coincidence that pre-established range settings were 800 to 1000 meters?

[Vanir]

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

Given the current CM gunnery/ballistics model appears to be flawed, this thread certainly needs to be kept alive.

bump<HR></BLOCKQUOTE>

Of course they're flawed. And no matter how much they tweak and adjust it will never be perfect. Thats the nature of the beast, I'm afraid. Informative threads like these certainly never hurt, though

Heck, I'm surprised its as accurate as it is considering they never intended CM to be a tank sim. Its really more of an infantry sim.

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You've never heard music until you've heard the bleating of a gut-shot cesspooler. -Mark IV

[This message has been edited by Vanir (edited 01-18-2001).]

[This message has been edited by Vanir (edited 01-18-2001).]

[Iron Duke]

John...LOL!

<BLOCKQUOTE>quote:</font><HR>Ahh the imfamous Clancy version. IIRC this was debunked a while back. Their is a report on cause of loss on US units from the Gulf I had it saved till my HD crash. Paul if your lurking could you post it?.<HR></BLOCKQUOTE>

That doesn't surprise me.

Tales like that one spread through a unit like pimples on a teenagers face.

Jeff D...

then to answer your original question: No, I do not know of any M1's that where penetrated by Iraqi main gun hits. And as John has pointed out, of all the tanks in the "Tiger Brigade" that fought at 73 Easting, only 4 of those where hit but I take it no penetrations. Is that correct John? You said damaged...but no penetrations?

Jeff D...I'm getting ready to head out for work so I will answer your training questions once I get there. (Kind of long )

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One shot...One Kill

[Jeff Duquette]

Duke:

Thanks, looking forward to reading your post.

<BLOCKQUOTE>quote:</font><HR>VANIR Said:

Of course they're flawed. And no matter how much they tweak and adjust it will never be perfect. Thats the nature of the beast, I'm afraid. Informative threads like these certainly never hurt, though<HR></BLOCKQUOTE>

Unfortunately there aren't really underlying physics in the game regarding ballistics. Look at Steve's comments on bracketing at:

http://www.battlefront.com/discuss/Forum1/HTML/014401.html

The little tracers you see in the game representing rounds being fired are simply eye candy. There is apparently no real correlation between the tracers and targeting/bracketing etc. Steve had indicated there are some simple functions to make the tracers look like they are arcing, but hitting a target appears to be fairly traditional gaming approach of a simple "to Hit probability" table ala a common table top miniatures game. The engine apparently models bracketing via an added "to-hit" percentage. At least that is my understanding from reading various postings by Steve.

Don't get me wrong, this is fine by me. I still enjoy playing the game, and I agree with you that the intent of threads like these are simply food for thought.

I like the underlying BTS Design philosophy for Combat Mission: CM focuses on realism and attempts to be a simulation rather than a game. So part of the intent of threads like these are - in my mind - to talk about the differences between simulation and gaming. The two can never be mutually exclusive, but you can still try. What is too "gamie" and what is delving to deep into "simulation"?

[ASL Veteran]

better be careful Jeff, Steve roasted and toasted me in the 'big' accuracy thread for stating nearly the same exact same thing you just said. Of course, that was right after the big (and possibly infamous) mega flame war in the German optics thread, so maybe Steve was under a little duress at the time.

[ASL Veteran]

Oops, double post

[This message has been edited by ASL Veteran (edited 01-18-2001).]

[Paul Lakowski]

I know who 'rexford' and 'we' are and I've always deferred to them in the past.

BTW didn't Nashore always use a arty range finder, which is the only reason it boasted such a long range accuracy.

[rexford]

Regarding the original message on accuracy,it appears that 500m hit percentages are limited by tank gun elevation on German heavy tanks and Sherman, guns that have to shoot at targets below the barrel have to use a very curved trajectory which reduces accuracy. High set and slow guns like 75L40 on Sherman suffer even more, trajectory is curved to start with due to low speed and shooting at lower target center of mass introduces even more error.

Our results for shots beyond 1000m probably will hold if target is within 0.7m of gun barrel, otherwise things might change.

Could Nashorn get more than 10% hit probability on a shot at 2000m after repeated tries? Start at 10% range estimate error and range error quickly decreases through bracketting to much more than 10% hits per shot. With range finder 2000m becomes a high % shot after bracketting.

At 3000m Nashorn is limited by random scatter from shot to shot, so 1,000 shots won't improve over 8th shot. Even if range is right on at 3000m, misses will occur on a regular basis (and this does not consider wind gusts or crosswinds).

One response to a post on weapon cant (one side of gun higher than the other) pointed out that defenders usually pick locations where one wheel of gun, or track of track, won't be higher than the other and lead to lateral errors on long range shots. Nashorn crew takes time to set up on level ground, breaks out range finder or scaled map of landmarks, and waits for enemy.

Shermans or IS tanks burst into open, some might stop and fire back from terrain with side slopes, first shot misses that are quickly corrected. So many advantages to defender and the number keeps going up.

There is a story of a single Jagd Tiger that decimated a large number of Shermans. Knock-outs can be more than just a gun and armor, picking the right terrain (no cross slope), long and clear fire lanes and having landmark distances but big advantages. If 128mm gun was lower than Shermans, this would also add slightly to accuracy at long range (though it might not have been known to be a bonus).

Although no wargame can claim highly accurate or even highly realistic figures, there are certain hit % ranges that are reasonable and can be supported. The trick is to present reasonable figures.

[ASL Veteran]

I’ve been lurking on this accuracy thread, and now that we have Rexford here I want to bring up two questions that I got stuck on in the original accuracy thread. There was a lot of talk by Tom and others that seemed to lean towards the equation of high velocity = greater accuracy. This would also seem to be demonstrated with the “TigerFibel” training chart thing. However, I noticed that in Jentz’s book “Tank Battles in North Africa” the accuracy of the 75L24 is almost identical to the 88 Flak out to 1500 meters, beyond which there is no more data for the 75L24. This would seem to indicate that higher velocity does not necessarily = greater accuracy. This lead me to explore the issue a little further. I began to notice that HE shells are lighter than AP shells, but that they always travel at a lower velocity. Heavy shells at high velocity, light shells at low velocity.

I would guess that the HE shells would travel at a lower velocity because they don’t need to penetrate armor .. you just need to get the shell on target. So here is the first question – IF a light shell is traveling at a lower velocity than a heavier shell, THEN does that necessarily mean that the heavier shell at the higher velocity is inherently more accurate than the lighter one at the lower velocity.

To complicate matters, an APCR round is a very light shell at a super fast velocity – if velocity were a direct function of accuracy, then it would follow that an APCR round would be more accurate than either an AP round or an HE round. However, Ian Hogg in “The Encyclopedia of Infantry Weapons of WW 2” says, referring to the PAK 38s APCR round, “due to the light weight of the composit rigid shot, its ballistic coefficient (best visualized as staying power or carrying power) was poor, and at longer ranges the improvement became marginal.” He was referring to penetration in that specific quote, but it can be inferred that accuracy was reduced as well at longer ranges.

Here is the second question: It seems to me that accuracy would not necessarily be strictly a function of velocity, but of the weight of the projectile as well. The ‘Ballistic Coefficient’ seems to be a rather important item towards accuracy and I was curious to know if Rexford has tackled Ballistic Coefficients at all.

[Jeff Duquette]

Interesting that there quite a few weapons seemingly more accurate than the dreaded 88.

From Jentz and a OPerational Research Study on the 6 pdr and 17 pdr. 90% dispersion. 2x3 meter target size.

[rexford]

Accuracy as hit probability % is a function of two factors, velocity to a given range and dispersion.

An 88L71 fires at about 2.6 times the muzzle velocity of 75L24, so the 88 trajectory is much flatter. Flat trajectories mean that the ammo flight path doesn't change as much if the range estimate is in error, so a higher percentage of hits with expected range estimate errors with flat trajectory.

The Jentz figures are for tests where the range is known, and the round to round scatter is measured and compared to a standard target size. Jentz accuracy says that when the 2 pounder and 88L56 have been set to the exact range of the target, the 88 will hit more often.

When range estimation isn't 100% correct, most shots, the 88 will be close to the target more often than 75L24. Having smaller scatter at constant aim (Jentz figures) means that when range estimate puts aim at edge of target, fewer shots will scatter off the target.

Trajectory is primary factor effecting accuracy, scatter plays a secondary but important part.

Although 17 pounder APDS with its' high speed would not have a flat trajectory if scatter was high due to sabot pieces sticking on round, which they did. In 17 pdr APDS case, scatter could totally destroy flat trajectory effect (at Isigny, 7 of 24 17 pdr APDS shots at Panther missed from 200 to 800 yards). In most cases trajectory and velocity rule.

At long range, scatter limits the accuracy one can obtain. Even if aim is right on target a good percentage of shots at 3000m will scatter off the target.

Scatter is due to differences in ammo powder charge and weight, gun recoil and tank reaction to shot, barrel reaction, etc.

[rexford]

We don't mess with ballistic coefficients, we have tables for velocity vs. range.

88 APCBC from Tiger loses a smaller % of velocity with range than Panther 75mm due to two factors:

heavier rounds lose less speed with range for given air resistance (reason why a heavy softball can be thrown further than a near-weightless ping pong ball).

faster rounds lose energy and speed faster, since air resistance proportional to velocity squared.

20mm rounds lose velocity very fast, 152 very slow.

Another factor is shape, which we don't deal with due to velocity vs range tables. Rounds without caps have points but can't be too sharp since they would not penetrate angles very well. Ballistic caps streamline round so it has less air resistance.

Sherman 75mm APCBC (armor piercing cap, APC, with ballistic cap, BC) loses penetration much slower than 75mm AP although both shot at 2030 fps from Sherman. However, 75mm AP penetrates 113mm at 0m, 75 APCBC only 91mm. 75mm AP could hole Tiger front at close range!

Difference is due to two factors:

75mm AP is solid shot, and HE burster costs a round about 8% to 10% of penetration. APCBC caps absorb energy upon impact without adding too much against homogeneous armor, so caps lose about 10% to 12% of penetration.

So why use a cap? 75mm AP shatters alot against thick armor (armor thickness equal to or greater than projectile diameter), and caps may decrease probability. Caps increase penetration against face-hardened armor, so 75 APCBC penetrates more face-hardened armor than 75 AP, and APCBC penetrates more homogeneous at long range due to slower velocity loss.

Note that 75mm AP shattered at impact velocities below 2000 fps. U.S. tests showed that 75 APCBC didn't shatter too often.

Soviets use 100, 122 and 152mm rounds with ballistic caps that carry alot of their penetration to long range, due to heavy weight and cap. One factor that tells if a round is good ballistically is weight over diameter squared, since weight indicates if round has carrying power and diameter squared suggests relative air resistance.

152mm APBC is 108 lbs divided by 6" squared, or about 4.2. 37 APCBC is 1.92 lbs divided by 1.5" squared, or less than 0.90. U.S. 76mm APCBC has 15.44 lbs divided by 3" squared, for 1.75.

Big rounds carry well, like 152mm APBC, but SU 152 could only get out between 1 and 2 shots per minute. Alot less shots per minute than an M10.

Good questions, hope this fills the bill.

[Fred]

very interesting discussion. And it seems as if both sides better had used scientists instaed of soldiers if they are for a win (germany tried, but the V1 and V2 were not very decisive).

Charles stated it. In all the elaborate formulas, charts and tables about ballistics it is the human factor that makes the difference (if it comes down to 1 or 2 meters). Sometimes its just luck (chaos theory anyone), or a perfect hit but the round was a dud.

Implementing some clean "out-of-the-real-world" charts and formulas would not make CM any better, but more predictable.

And there is nothing like "predictable" results, just probabilities, according to current scientific views, especially on a place ruled by chaos, called the battlefield.

Fred

[This message has been edited by Fred (edited 01-19-2001).]

[rexford]

Competent Nashorn crews take advantage of chaos and use it to their advantage. Bracketing takes the human tendency to error and mechanically reduces the errors by small bits until one "zero's in" (although not to 100%).

Cool nerves and bracketing reduce errors and boost hit/kill chances. Should a game deny this, the calm cool kill of the true professional.

[Paul Lakowski]

As I understood it the 75L24 was developed from the 75mm IG which is known for its accuracy.

As to APDS , one of the big problems is seperation of the sabot pelts or pot sabot after it leaves the barrel. If theres even the slightest contact with the subcalibre projectile it will 'kick in' a large amount of error or dispersion.

[:USERNAME:]

http://www.warlinks.com/equipment/tank_research/section_c.html

[Jeff Duquette]

Great stuff Rexford.

[Jeff Duquette]

Especially the bit about professionalism. I'd like to add training to your post.

This all goes beyond combat experience, although combat experience –by most people’s assessment – is a key ingredient to successful combat formations. The Coalition Army that went into the Gulf was basically an amalgamation of Green Panzer Truppen (some were probably even scientists ). Yet we read of 4000 and 5000 meter first round kills. LRF’s or not these are impressive ranges by even modern tank gunnery standards.

[rexford]

One of the odd things about accuracy is that flat trajectory guns are very good at hitting vertical targets but stink when it comes to landing HE near a specific horizontal ground point.

German ballistic data shows vertical dispersion greatly effects the ground fall of high speed HE rounds, and has less effect on low speed HE. So if one wants to land an HE round within 20' of enemy infantry, use 75L24.

If you want to hit a 4' high target at 800m on the fly, use 75L70.

Short guns with low velocities can have superior accuracy against ground point targets. This may be what was meant in the reference to 75L24 accuracy.

[:USERNAME:]

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

One of the odd things about accuracy is that flat trajectory guns are very good at hitting vertical targets but stink when it comes to landing HE near a specific horizontal ground point.

German ballistic data shows vertical dispersion greatly effects the ground fall of high speed HE rounds, and has less effect on low speed HE. So if one wants to land an HE round within 20' of enemy infantry, use 75L24.

If you want to hit a 4' high target at 800m on the fly, use 75L70.

Short guns with low velocities can have superior accuracy against ground point targets. This may be what was meant in the reference to 75L24 accuracy.<HR></BLOCKQUOTE>

This sounds like something you are stating from fact but are really surmising. I completely disagree.

You disregard many factors in this statement. Not the least is flight time (the high velocity weapon gets there quicker), flight path (the longer parabola is under the effects of crosswinds/gusts at different heights), target reaction (maybe the people on the recieving end might not like being shot at and decide to move). You never mention range.

A high velocity gun is more accurate and therefore an initial miss can be corrected and subsequent shots brought onto the target.

Any completely "horizontal" target like infantry dug into a trench is difficult for all weapons to attack. Your point is moot and speculative.

Unless, of course, you use an airburst or ricochet fire.

Lewis

[Matthew_Ridgeway]

"You disregard many factors in this statement. Not the least is flight time (the high velocity weapon gets there quicker), flight path (the longer parabola is under the effects of crosswinds/gusts at different heights), target reaction (maybe the people on the recieving end might not like being shot at and decide to move). You never mention range."

By all means elaborate on this. I’ve read through this thread from start to finish, and I did not come away with the impression that this fellow Rexferd ignores any of your points. Do you have an alternative mathematical approach to explain your arguments?

[This message has been edited by Matthew_Ridgeway (edited 01-20-2001).]

[Theron]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Jeff Duquette:

Interesting that there quite a few weapons seemingly more accurate than the dreaded 88.

From Jentz and a OPerational Research Study on the 6 pdr and 17 pdr. 90% dispersion. 2x3 meter target size.

<HR></BLOCKQUOTE>

I don't have the book, but I'm wondering what this graph really means. There are points on the graph (evey 500m) which appear to be data points, but they could just serve to further differentiate the the various curves. Therefore my first question is are these data points? The second point I would like to make is that I can understand why the 88 and 75L24 are very desirable guns at short ranges. At less than 500m the probability to hit > %100. So if this is not data with a fitted curve and is a model why does it predict a to hit > %100?

Theron

[:USERNAME:]

By all means elaborate on this. I’ve read through this thread from start to finish, and I did not come away with the impression that this fellow Rexferd ignores any of your points. Do you have an alternative mathematical approach to explain your arguments?

[This message has been edited by Matthew_Ridgeway (edited 01-20-2001).]

[:USERNAME:]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Paul Lakowski:

As I understood it the 75L24 was developed from the 75mm IG which is known for its accuracy.

.<HR></BLOCKQUOTE>

I never knew that