Penetration vs. Range

[KillKess]

Since SB "only" provides us with penetration values for muzzle velocity, how can one calculate the penetration at various ranges? How to calculate the velocity drop vs. range for a given round?

[Gibsonm]

I think the bottom line is that unless you work in a suitable institution (like the Royal Ordnance Factory) or already have access to the data and relevant formulae, you can’t.

eSim does have these resources though.

There are resources for such work on the Internet (of various quality) so you are welcome to search and then do all the math to generate your own set.

[Grenny]

...how good are your in fluid-dynamics?

Get the properties of your projectile...the properties of air(densety, temperature etc etc etc)...run a CFD-simulation=> job jobbed ;-)

[GH_Lieste]

Most should be within 85-95% of muzzle at effective range - to all intents and purposes no significant variation with range.

It is only important when the armour is only slightly below the penetration capability of the round - and shot placement is then far more important - the variation between protected and non-protected areas of the frontal array is usually 5-6 times this with-range variation of modern KE rounds.

BM9 is capable of perforating the M1A1 from the front if it strikes a weaker area - even at 3km, while BM32 might fail against the protected front slope of the turret at the muzzle.

[SeanPatrick]

I have a simple program for Texas Instruments Calculators which simulates and graphs projectile velocity over time. I can post the code if anyone's interested.

[Ssnake]

Since SB "only" provides us with penetration values for muzzle velocity, how can one calculate the penetration at various ranges?

Well, there's Willi Odermatt's website on long rod penetrators.

How to calculate the velocity drop vs. range for a given round?

Typically the Vdrop is in the range of 40...80m/s per kilometer flight distance - for large caliber APFSDS rounds. But ultimately you can get these data only from ballistic tables which aren't always in the open.

You may want to inquire in the "Armor Scientific" board of the TankNet.org forum.

[KillKess]

Most should be within 85-95% of muzzle at effective range - to all intents and purposes no significant variation with range.

From my understanding this would also mean that penetration should also be within 85-95% off the penetration value at the muzzle. Am i´m right?

Thx for all awnsers, ill give TankNet a try the next days.

[Eisenschwein]

Check this, Tables are on the Button:

http://www.kotsch88.de/munition.htm

Sorry, it´s in german only.

[Companion]

Please, allow me to digress a bit and saturate you with some questions:

How the 3BM32 and 3BM42 differ in performance? By just looking at muzzle pen. and velocity information available at SB, they are almost identical.

Same question also applies to 115mm KE series and 30mm AP and APDS.

Also in some cases, subsequently developed rounds actually perform marginally worse than its predecessor, why? Why bother producing rounds that are no better than what you already have?

Just one more: Some rounds such as L64A4 and M728 are APDS rounds, right? Then how come they show similar or even better performance than some APFSDS rounds such as M111 and 115mm series?

Seeing much touted 115mm APFSDS (If "The world's first APFSDS" means anything) on the lowest end of the spectrum came as a shock to be honest.

[Captain_Colossus]

Please, allow me to digress a bit and saturate you with some questions:

How the 3BM32 and 3BM42 differ in performance? By just looking at muzzle pen. and velocity information available at SB, they are almost identical.

I've never seen any two sources agree on anything about these rounds; according to Kotsch, 3BM32 is a dU-zinc-nickel alloyed penetrator encased in steel, 3BM42 is a Tungsten alloyed penetrator encased in steel. Kotsch says that 3BM42 outperforms 3BM32 at 2km.However, Vasily Fofanov reverses this scenario and gives wider variation between these two than the Kotsch website, that is to say, the dU penetrator outperforms the Tungsten penetrator by a wider margin at 2km.

[Ssnake]

How the 3BM32 and 3BM42 differ in performance?

Those who know for sure must not talk, everybody else is just speculating. Some are speculating from a comparatively well educated background, others not so much.

BM32 is dU, BM42 is tungsten, and that's about all I'm willing to say here. The values in SB Pro are guesstimates, they can easily be off. We just try to document in the user manual how we arrived at the figures that we are using. But we make no claims that SB Pro presents "the Truth".

Also in some cases, subsequently developed rounds actually perform marginally worse than its predecessor, why? Why bother producing rounds that are no better than what you already have?

Much would depend on the individual situation. Penetration depth is only one of many metrics to rate the quality of a round. For example, to achieve maximum perforation depth a penetrator should be as thin and long as possible, have a high density, and high hardness. Make it too thin, and it fractures in the barrel, or can be defeated with reactive armor arrays. Make it too hard, and it becomes brittle. The thinner a penetrator, the less fragmentation it generates behind the armor.

Therefore, looking at a single metric - admittedly one of the more important data points - can never tell the full story.

Also, some rounds may not be available as easily as another round of similar performance.

Finally, maybe we simply made a mistake. Whatever the reason, the figures that we have represent our best guesses, which sometimes are well educated and sometimes bordering on wild speculation. The data are hard to find, sometimes you need to fill in a lot of blanks and have little to work with.

Just one more: Some rounds such as L64A4 and M728 are APDS rounds, right? Then how come they show similar or even better performance than some APFSDS rounds such as M111 and 115mm series?

The 115mm case is pretty simple to explain - Steel as the penetrator material. also, being the "world's first APFSDS" doesn't mean much. APFSDS simply describes the basic projectile design. As the 115mm gun was a smoothbore barrel, by necessity the subcaliber rounds had to be fin stabilized (the "FS" part of the designation). DS just means that the sabot gets discarded after leaving the barrel in order to reduce the aerodynamic drag characteristics in flight, so except for the very first saboted subcaliber designs all sabots were of the discarding type. And that's it -

AP: Armor Piercing

FS: Fin Stabilized

DS: Discarding Sabot

Big deal.

[Companion]

Those who know for sure must not talk, everybody else is just speculating. Some are speculating from a comparatively well educated background, others not so much.

BM32 is dU, BM42 is tungsten, and that's about all I'm willing to say here. The values in SB Pro are guesstimates, they can easily be off. We just try to document in the user manual how we arrived at the figures that we are using. But we make no claims that SB Pro presents "the Truth".

Ok, I think I heard that enough to automatically remember it in any ammo discussion :debile2:

Now I just want to know which round has better chance of hurting that Leo shooting at me in-game.

[GH_Lieste]

According to the Odermatt system of equations and for the best ratio of energy/penetration, Steel needs very high velocities~ 2km/s, WHA really prefers high velocity ~1.65km/s , and DU is happier at mid velocities ~1.35km/s.

While velocity drop can vary from one round to the other, the difference between material is more significant, except in cases of extraordinarily clean or draggy rounds - so BM32 should be the better long-range round if you can obtain an equal number of hits - ultimately accuracy and consistency is far more important than raw penetration.

[Big Nose Zero-Three]

BM32 is dU, BM42 is tungsten, and that's about all I'm willing to say here. The values in SB Pro are guesstimates, they can easily be off. We just try to document in the user manual how we arrived at the figures that we are using. But we make no claims that SB Pro presents "the Truth".

As I am sure Esim is well aware, various editions of SB have been used by some pretty well respected military organisations to examine weapons performance or when they can't access the classified armour performance data.

"Fit for purpose" were the words used to me.

[Grenny]

SB is a really great simulation software, but using it as source to determine weapon/armour performance IRL, is like citing wikipedia in your masters-thesis :-)

[Big Nose Zero-Three]

SB is a really great simulation software, but using it as source to determine weapon/armour performance IRL, is like citing wikipedia in your masters-thesis :-)

Concur, but you'd be amazed at the academic and military journals now that cite Wikipedia!! .... and as I constantly have to remind folks, citation is not verification!!

As I said, it isn't used to determine anything. It is used as an unclassified data set on which to base discussion and experimentation on wider force development and doctrine issues.

Plus I know for a fact that what SB does do in terms of weapon/armour performance has really surprised some OR scientist types.

.... and, if the weapon/armour performance in SB isn't a useful approximation, then it has no training value. IMO, indeed a great simulation, and SB simply has no competition in this regard.

[Ssnake]

Well, our yardstick in absence of verifiable data is plausibility, which is about as low as it gets without becoming totally hokey. We always and explicitly point out that, despite our attempts to deliver good results, SB Pro is simply not made for quantitative statistical analysis. I devote at least half an hour in my software training to point out the limitations of our model. We have a great spatial resolution, but what happens in post-perforation situations is anyone's guess (well yeah, lots of sharp bits of hot metal will fly around - so much is a given. But should the likelihood of a radio set to be damaged indirectly be 10%? why not 11%? or 40%? Who can say?).

Training value... well, it depends on what your training goals are. If you want to establish the exact range at which your ammo X is able to perforate target Y from some specific aspect, go somewhere else. If your training goal is to point out that it's better to strike from the flank than from the front, be my guest.

I've witnessed hair-raising misinterpretations of Steel Beasts combat results. To give an example, just because you accidentally hit a T-72 at a range of 3500m with a medium caliber APFSDS in the triangular spot between sideskirts and roadwheels and manage to conflagrate the ammo carousel does NOT mean that you should routinely attempt to do that with an IFV, if you have to expend on average between 15 and 20 rounds due to the shot dispersion. Rewriting the doctrine for your IFV because of such a spurious, anecdotal "evidence" is absurd. Yet sometimes it is tried. Therefore I feel compelled to point out over and over again that this is not how you should use SB Pro.

We try to be better than what we advertise, yes, but there are absolutely no guarantees beyond our advertised limits.

[Big Nose Zero-Three]

Rewriting the doctrine for your IFV because of such a spurious, anecdotal "evidence" is absurd. Yet sometimes it is tried. Therefore I feel compelled to point out over and over again that this is not how you should use SB Pro.

Luckily most doctrine writers are not that stupid - though some are!

All simulation tools have to be used wisely, and the example you cite would be an excellent example of showing how not to do it, and exactly the sort of thing force developers and doctrine writers would ignore.

What good simulation does really well (and is proven to do) is showing the limitations or the potential of an idea, before people wander off and spend millions in live trials.

[Ssnake]

Maybe I have read more into the emails that I got, or slightly embellished the description here for dramatic effect. Still, it is somewhat irritating to see how otherwise quite intelligent people who "should" know better sometimes draw wild conclusions simply because "they saw it" in a computer simulation (as if computers were never wrong, and the GIGO principle didn't exist).

We are feeding our simulation with garbage. It may be high quality garbage, but no matter what, the results inevitably must be junk even if the underlying model isn't too bad, so that the overall result still appears somewhat palatable. I suspect that the "seeing is believing" mechanism is also at work in most cases where computer games are re-applied for the training role, with little regard to a didactic analysis or an actual, scientifically rigorous investigation of the methodology of such a computer game.

"The end users think it's great" is often enough the only justification for the employment of a game in training. I may be hurting my own business, but I think that more is needed to separate the wheat from the chaff, especially since I am convinced that SB Pro is more wheat than chaff, and looking at how many millions are thrown at the chaff just because it glitters so nicely in the air. :cul:

[Gibsonm]

We have a far more rigorous approach to using sim to evaluate plans.

Its:

30% use of SB Pro

30% the result of an offering of goat's entrails to the Tk God

30% coin toss (to keep the statisticians happy)

10% "what do you reckon?" over brews at Morning Tea

If a given plan achieves 60% or more from this then we commit.

(Now I'll have the guys from DSTO and DMO on my back).

[Grenny]

In that case, it most clearly the the emperor in the intercom:

Gunner:"identified, tank, front 3500"

Emperor Mong:"Well my subject, go ahead an kill it."

Gunner:" Yes my liege. But that wont kill it! What if he shoots back?"

Emperor Mong:"Dare you question my judgement!!! Have you not seen it work on SB! What can go wrong?"

Gunner:"Of course my lord, he shall get it!"

-bam-

Gunner:"Hmm, that didn't kill him,Oh no now he is point this gun at us...emperor what should I do?" and with a puff, the emperor was gone...

Edited December 16, 2011 by Grenny