Real Armor (mm)

[T-34/85]

Hi, I love this game and I thing this game is very realistic but, ...well...In enciclopedy it says the tanks mm of armor but theres alot of tanks that are not correct...Like for exemple, kingtiger add 180mm of front, T-34/85 add 90mm of front...Other T-34s add 50mm...Panther add 110 (The D only add 100mm) and so on... Its just I dont want any tank be pushed beyand because of a wrong armor.....well come on....can u imagine (I dont know if is possibel in the game...just an exemple) a Panther been killed by a 75mm gun of a sherman or a 76mm gun of a T-34 at a range of 600m, 700m? Its that im talking about, I dont want no tank is over powered or overweak...Because i really like realism so i can use real strategy and relife ww2 tank battles...

Anyways its a great game...I just hope this (MM of armor) as I sayend push a tank beyand because a wrong armor...

Thanks, I just hope a mod or a patch or whatever been done for this...

[Sneaksie]

And what front turret armor values you think will be correct for these tanks?

[danjeje]

As far as I know the thickness of the armors are correct. (for all the tanks I have checked)

But how is evaluated the slope of the armor?

I never found this data in the game and in the files of the game.

[Sneaksie]

All data values in the game are without slope; it's effect calculated during each hit depending on actual angle between shell trajectory and armor.

[T-34/85]

So are you saying that in the book im reading (Jane`s World War II Tanks) Is wrong or it says the armor with shape? I think no because how can the normal T-34 have 50mm and T-34/85 have 90mm of front??? In the game is very equal the t-34s...I none of the armor correspond to my book (I checked other books and his same or very close)

[Sneaksie]

Look closely - these are values for front turret armor, not hull. Late series of T-34-76 had 50-52mm front turret armor and T-34-85 had 90mm of front turret armor, while it's front hull armor was 45mm during entire war.

[T-34/85]

Well, thinking well, you are probaly right, so now im happier because the game isn t wrong...but one thing...wow so, T-34 burn fast......lool Thanks

[danjeje]

Originally posted by Sneaksie:

All data values in the game are without slope; it's effect calculated during each hit depending on actual angle between shell trajectory and armor.

This mean that the angle of the hit are calculated using historical data of the angle of each armors?

[T-34/85]

ye, i think

[ShiftZ]

The game should be using trig to figure out the increase or decrease in armor thickness in relation to trajectory of shell and target.

If the slope of any given target is at 90 degrees the thickness of the armor will be nominal. If however you decrease the slope away from the incoming round the amour rating increases. Lets say target hull is on a 30 degree slope from the horizontal with the front end facing up. The targets turret would then be advanced to 60 degrees from the vertical giving the armor a great increase in thickness if the round fired is approaching the front end. 90mm of turret armor at 90 degrees would double to 180mm at 60 degrees from the vertical.

I’m going to make an assumption that the game is using trigonometry to make these calculations or at least geometry. I could be wrong. Obviously there is a lot of stuff going on here.

[Jeff Duquette]

Ballistic slope effect is different and somewhat more complex than simple line of sight thickness would imply. Line of sight thickness being simply t/cos(theta)-- where(theta) is the compound angle between side angle of the shot and actual slope of the plate.

Slope effect is the actual increase in limit velocity (or apparent thickness if you like) required by a projectile to perforate sloping armor. If one were comparing the limit velocity for a vertical plate with that of the same "line of sight" thickness for an inclined plate, slope effect can result in a much higher limit velocity; or the same; or even a lower limit velocity than what the simple t/cos(theta) relationship will predict.

[ShiftZ]

So Basically it all depends on how the gunner is holding his mouth?

[Jeff Duquette]

Originally posted by ShiftZ:

So Basically it all depends on how the gunner is holding his mouth?

That's part of it. But you also have to consider the phase of the moon as well as local tidal conditions and the height of the pyramids.

[Jeff Duquette]

Not that it matters to the price of butter in Slovenia, or relative to more interesting things to yakk about regarding the recent patch. But to be clear, there really isn’t much in the way of voodoo at work with armor penetration. It’s just that it is often brought up on forums such as this one. In fact, it has come up a number of times on this forum, to include this thread.

The “cosine rule” – while applicable under certain conditions of plate penetration – is really only valid under limited circumstances.

What’s the cosine rule? In the way it is typically put forth – ala this particular thread – is that plate ballistic resistance to armor piercing projectiles that rely predominately upon their kinetic energy to perforate armor is somehow directly proportional to the line of sight thickness of the armor plate. This isn't really true, at least under most conditions.

What is a plate’s Line Of Sight Thickness (LOSt)? Let’s say a plate has no inclination – it doesn’t slope. It’s actual thickness is the same as its LOSt thickness. If the plate is inclined at say 30-degrees, than it’s line of sight thickness (LOSt) is going to be greater than its actual thickness. The LOSt thickness is equal to the actual plate thickness divided by the cosine of the angle at which the plate is inclined. For example:

If a plates actual thickness is say 77.9mm and it is inclined at 30-degrees, than the LOSt is simply:

LOSt = 77.9mm/COS(30-deg)

Cosine(30-deg) = 0.86604

Therefore LOSt = 77.9 / 0.866 = 90mm

If a plates actual thickness is say 51.6mm and it is inclined at 55-degrees, than the LOSt is simply:

LOSt = 51.6mm/COS(55-deg)

Cosine(55-deg) = 0.57363

Therefore LOSt = 51.6 / 0.57363 = 90mm

IMAGE-1 Actual Plate Thickness vs. LOSt

As I was saying, folks often want to try and explain the superiority of an inclined plates ballistic protection capability by the plates line of sight thickness. The plate is thicker along the diagonal. Therefore it resists more. But there is more to inclined plate ballistic limit than simply the apparent thickness along the diagonal.

Now let’s consider how much umph it takes for a projectile to penetrate a given plate of roll hardened armor. The following example is for circa-WWII, US-Army 90mm M82 Armor Piercing capped projectile. This is a pretty common shell that was employed by the T-26 Pershing Tank and the M-36 Jackson Tank Destroyer.

The following figure is how much impact velocity the projectile requires to completely pass through a armor plate of various thicknesses and at various inclinations.

IMAGE-2: 90mm M82 APC Limit velocity vs. RHA as a function of t/d

How to read the above graph: The X-Axis or horizontal axis is presented in terms of t/d. t/d is simply a common means of presenting penetration data in terms of the projectile diameter or projectile caliber, divided by the thickness of the plate being attacked. For example:

At t/d = 1 the thickness of the plate is simply:

Projectile Diameter, d = 90mm

Plate Thickness, t = 90mm x 1 = 90mm.

The plate thickness at t/d = 1 is therefore 90mm.

At t/d = 1.5 the plate thickness is simply 1.5 x 90mm = 135mm

At t/d = 0.5 the plate thickness is simply 0.5 x 90mm = 45mm

As I am talking about the validity (or lack of validity) of the often quoted cosine-rule, the t/d values for the penetration data represents the line of sight thickness of the plate rather than the actual plate thickness. For example:

For 30-degrees and t/d=1 the LOSt – like that of the plate with zero inclination -- is also 90mm. However the actual plate thickness is only:

90mm x cosine(30) = 77.9mm.

The vertical axis of the graph is the amount of velocity the projectile requires at impact to completely pass through the plate. For example

At t/d = 1 and inclination = 0-degrees, the impact velocity required for the projectile to pass through the plate is about 1900-feet per second.

At t/d = 1 and inclination = 30-degrees, the impact velocity required for the projectile to pass through the plate is also about 1900-feet per second.

At t/d = 1 and inclination = 55-degrees, the impact velocity required for the projectile to pass through the plate is a smidge over 2200-feet per second.

Why the cosine-rule is not always wrong, but why it is not very accurate the vast majority of the time.

The following figure (Image-3) compares the ratios of velocity required for the 90mm M82 APC projectile to perforate a plate inclined at 0-degrees to that of a plate with the same line of sight thickness (LOSt) when the plate is inclined. So LOSt is being held constant between the zero degrees inclined plate and the plate inclined at either 30-degrees or 55-degrees. When this ratio of limit velocities is equal to 1 for a specific t/d value, than it can be said that the cosine rule accurately predicts the level of ballistic protection the plate provides against 90mm M82 APC. When the ratio is less than 1, or more than 1, than it can be said that the cosine rule does not accurately predict the level of protection provided by the plate at the given inclination.

As the figure shows, except for a couple of very discreate points, the cosine rule doesn’t accurately portray the level of ballistic protection provided by an inclined plate in the majority of situations considered. For all the t/d values considered for the plate inclined at 55-degrees, the plate is providing much more resistance than the simple cosine rule would imply. For 55-degrees inclination, you’re always better off with the inclined plate.

For the 30-degree inclination, when the LOSt t/d ratio is near 1, the cosine rule is pretty accurate. But for t/d less than 1, and 30-degrees inclination, you’re better off going with vertical armor. For t/d greater than 1, and 30-degrees inclination, you’re better off going with the inclined plate.

The cosine rule can be used as a sort of ballpark figure for plate inclinations of about 30-degrees or less (depending upon the projectile type). But for greater inclination – such as 55-degrees – it can be said that the plate is providing a much greater level of ballistic protection than the simple cosine rule would predict.

IMAGE-3: Ratio of Limit Velocity Required to Perforate LOSt at Inclination vs. Same Thickness of Plate at Zero Degrees Inclination. 90mm M82 APC vs. RHA.

And finally – just for grins – below is a sequence of images of a projectile perforating an inclined plate. As you can see the projectile does not follow a straight line path through the plate. The projectile is subjected to several direction changes as it passes through the plate. Each direction change is resulting in rather large amount of stress developing within the projectile. But as you can see, the projectile does not follow the straight LOSt path through the plate.

IMAGE-4: Projectile passage through inclined plate.

Best Regards

JD

[ May 28, 2008, 09:23 AM: Message edited by: Jeff Duquette ]

[Sneaksie]

Whoa...

Well, in addition i must confirm that every angle of hit in the game is calculated in 3D space, but it's only the beginning. If shell caliber is much more than armor thickness, it will just crush through it. It may ricochet, shatter, pentetrate. It may normalize on armor. After penetration it may detonate (APHE and such) or go further and detonate on next plate or component or after it. Each penetration or near penetration causes internal armor fragmentation. Blast wave, fragments and other factors are calculated independently.

All these 'it may' is not some randomize function, it happens due to angle, type of shell, type of detonator, caliber, armor thickness, etc.

[ShiftZ]

Hey Jeff that LOSt rule of thumb is nice, easy to remember. Nice post BTW. I may just borrow a few lines for another fourm someday.

[danjeje]

Good work JD.

I knew some of this things but not in a so great way!!!

how could I do something like that for other shell?

There is a mathematical way to do so knowing some simple data of the shell (weight, diameter) or not?

I'm very interesting in this.

And let me say that a tank whit a sloped armor of the same relative thickness of a tank whit vertical plate have at least the same weight but much greater dimension.

thus if there weren't other bonus for the use of the sloped armor there weren't any real advantage.

[ShiftZ]

Ok Jeff I have a question;

Whats your take on modern armor and the effect teflon coatings have on KE rounds?

[Jeff Duquette]

Are you talking about armor coated in Teflon, or projectiles coated in Teflon – ala Teflon coated bullets and body armor?

As an aside Teflon is employed in multilayer EFP liners. The Teflon portion of the liner enhances secondary, or behind armor effect. The penetrator portion of the liner – be it tantalum or whatever – wraps around the Teflon during projectile formation. That’s right; the Teflon is in the interior of the EFP. Aluminum can also be employed as the “inner” layer in EFP penetrators. But the use of aluminum appears to be for its pyrophoric characteristics. Conversely the Teflon is described only as being an “energetic material” when functioning as a behind armor effects enhancement. I do not know whether this implies a pseudo-PELE behind armor effect; or whether this implies the Teflon spontaneously ignites during very high energy impacts (ala aluminum powder). I’d guess the former.

I also recall reading something on another discussion forum about shaped charge liners that employ Teflon. It was indicated by whoever posted this bit, that Teflon liners provide enhanced penetration capability against ERA. But I have never come across any research papers that disscuss the use of Teflon liners and their efficiency against ERA. Even after passage of the ERA flyers, the Teflon jet would still have to perforate the primary armor shell of a tank. So I guess I’m skeptical – at least until I can find a bit more solid information on Teflon liners and ERA.

Regards

JD

[ February 03, 2008, 07:00 AM: Message edited by: Jeff Duquette ]

[Jeff Duquette]

I see you’re a Steel Beasts fan. Great game. Although I have been unable to get Steel Beasts PRO PE to play on my super-uber gaming computer I just had built. Something to do with Vista as well as the dongle. Pretty irritating considering I paid $100 for the game. From what I've read from Nils, it sounds like compatibility with Vista isn't going to happen. So I guess I bought a $100 mini-frisbee + dongel.

[Jeff Duquette]

Originally posted by Sneaksie:

Whoa...

Well, in addition i must confirm that every angle of hit in the game is calculated in 3D space, but it's only the beginning.

Presumably this would also imply that if one of my tanks is in a hull-down position, I won't be seeing very many hull penetrations or track hits or the like.

Originally posted by Sneaksie:

If shell caliber is much more than armor thickness, it will just crush through it.

This is the reason for normalizing penetration data into the form of t/d.

An under-matching event will result in a different plate failure mode than an over-matching event. For example, blunt projectiles are very efficient when perforating under-matching plates (a low t/d event). They are much more efficient than an ogival shaped armor piercing projectile nose in low t/d events. However this advantage progressively declines as t/d increases until at a certain point the ogival nosed AP projectile becomes the more efficient penetrator.

Things such as slope effects plate hardness, armor quality or armor types perform differently under differing t/d ratios. If they did not, than those graphs I posted above would be simple horizontal lines rather than curves -- i.e. a horizontal line would indicate slope effect and the like are independent of t/d (which they are not).

Originally posted by Sneaksie:

All these 'it may' is not some randomize function, it happens due to angle, type of shell, type of detonator, caliber, armor thickness, etc.

Yes. A limit velocity -- regardless of who was conducting the trials: German, USSR, USA, UK -- is always equated with a probability of penetration or perforation. But an in depth discussion of penetration\perforation probabilities combined with a long discussion on the merits (or lake thereof) of the often cited "cosine rule" would have only succeeded in confusing the issue.

Best Regards

JD

[flamingknives]

On a side note, it was my understanding that teflon coating on bullets was just a way to prevent damage to the barrel from the hard penetrator.

[ShiftZ]

Originally posted by Jeff Duquette:

I see you’re a Steel Beasts fan. Great game. Although I have been unable to get Steel Beasts PRO PE to play on my super-uber gaming computer I just had built. Something to do with Vista as well as the dongle. Pretty irritating considering I paid $100 for the game. From what I've read from Nils, it sounds like compatibility with Vista isn't going to happen. So I guess I bought a $100 mini-frisbee + dongel.

Jeff here is a link to the forums over at SB. Your vista problems and many others who run that OS have been looked at in great detail.

http://www.steelbeasts.com/sbforums/showthread.php?t=11502

Nice information on the Teflon thing btw. I ask because a friend of mine -who used to be in the Canadian Militia- told me about Israeli tanks knocking out Syrian tanks. It would appear that one T-62 was taken out with a Teflon round. The penetrator caught the side of the gun but instead of deflecting off of the target it “stuck” to the gun tube and continued on down slightly boring into the tube before penetrating the mantlet. One naturally assumes Teflon to provide a slippery heat resistant surface but it would seem that at high velocities these same qualities are to be reversed

[ShiftZ]

This link may also be of some assistance:

http://www.steelbeasts.com/sbforums/showthread.php?t=11416

[Jeff Duquette]

...looks rather painful. It appears like I will need to monkey with the dongel configuration, direct-x, and my anti-virus software settings. I suppose the direct-x bit has me a tad worried in how this will affect play for other games on my system. I don't seem to have any issues with other games and Vista -- to include ToW.

On the Israeli teflon coating...I assume this was an LRP you are talking about?