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Release: ArmoredBeasts 2.08

jeffduquette

FNG / Fresh Meat
Feb 19, 2008
339
1
0
Of course effective plate thickness is not 140mm -- 140mm is the LOS thickness of the plate (Line of Sight Thickness -- simple cosine relationship). Effective thickness is much more complex than a simple cosine relationship and is a function of t/d. It can also be a function of projectile bending strength, projectile nose shape, plate hardness, plate quality...blah blah blah.

Projectile effectiveness within the game is very often driven (as it should be) by side angle or aspect of the target relative to the firer. So unless the shot is straight on, invariably obliquity will be compounded as a function of side angle. When you are talking about a base plate slope of 55-degrees, effective thickness will increase rather dramatically as the true attack angle is compounded as a result of vehicle cant, side angle, etc.. Moreover the difference between plate effectiveness at say 60-degrees is rather dramatic relative to say 55-degrees.

Invariably people keenly interested in this sort of thing want to discuss firing trials and how these should be interpreted -- such as those carried out at Kubinka or the like. But this presumably has been kicked about on other threads on this forum.

Best Regards
Jeff
This was something I posted on Battlefront.com sometime ago. while not directly related to the topic at hand, it is related to Ha$h's comments above, and why the simple cosine rule is not a very good way to estimate armors "effective" thickness....

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. These discreate points are indicated by the two arrows on the graph. 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
 
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XAN

FNG / Fresh Meat
Nov 23, 2007
12
0
0
30
Ukraine, Kiev
BTW, AB brokes balance on many default maps.... So I have an idea:
Is it posible to split T34-76 m41 into T34-76 m41 and T34-76 m43; split T60 into t60 and T70? For many maps that will be historical accurate, and would be some try to rebalance back many stock maps.
 

jeffduquette

FNG / Fresh Meat
Feb 19, 2008
339
1
0
BTW, AB brokes balance on many default maps.... So I have an idea:
Is it posible to split T34-76 m41 into T34-76 m41 and T34-76 m43; split T60 into t60 and T70? For many maps that will be historical accurate, and would be some try to rebalance back many stock maps.

There isn
 

ha$h

FNG / Fresh Meat
Sep 10, 2007
17
0
0
У меня сложилось мнение, что этот мод делает человек, который никогда не читал ни мемуаров ни военных документов. Он начитался всякого рода сайтов (типа tarrif.net) и тупо перенес данные в игру. Болванка весом 25кг, выстреленная из ИС2, которая рикошетит от лба пантеры с 80мм брони, хоть и наклонной, вызывает иногда смех, а иногда жесткие маты.

But at the start of the scenario, the forces are pretty well balanced – The rear most spawn for the Germans has only two panthers and one tiger (the rest are MkIVs or Stugs) -- the Russians rear spawn has only two T34/85s and one IS2 (the rest are T34/76s and SU76s).
Спасибо, посмеялся хорошо. Это ты на т34\85 будешь с пантерами боротся, или на су76? Ах даа, на ИС2... Читай написанное выше.
 
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7-CLOWN-7

Active member
Jan 20, 2007
743
64
28
52
Pittsburgh
www.cellar-dweller.com
Issue with Armored Beasts 2.08. For whatever reason no matter what you do, the armoredbeasts2_Welts_Tex.utx even when converted and put in Quick Downloads will NEVER download via Quick HTTP, it always gets it from the server which causes the download time for this file to be like 5 minutes or so and it's only like 900k as a uz2 file?

This happens regardless of whether I compress it myself or download it from all the proper places that house it.

Has anyone got this working with Quick Downloads? Every other custom files work perfectly fine, ONLY this file will not work properly and I have practically every custom on our server without issue with the Quick Downloads.
 
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Hans Sachs

FNG / Fresh Meat
Apr 21, 2006
91
2
0
44
JAPAN
seikouudoku.info
Issue with Armored Beasts 2.08. For whatever reason no matter what you do, the armoredbeasts2_Welts_Tex.utx even when converted and put in Quick Downloads will NEVER download via Quick HTTP, it always gets it from the server which causes the download time for this file to be like 5 minutes or so and it's only like 900k as a uz2 file?

This happens regardless of whether I compress it myself or download it from all the proper places that house it.

Has anyone got this working with Quick Downloads? Every other custom files work perfectly fine, ONLY this file will not work properly and I have practically every custom on our server without issue with the Quick Downloads.
The same problem occurred also with our server. Download of utx_uz2 file is very slow.:(

A next version is expected. I want to use this Mut with our server very much.:)
 

Shurek

FNG / Fresh Meat
May 21, 2006
857
13
0
www.darkesthourgame.com
As far as I know, Amizaur has moved on to other projects and has no plans to modify A/B any further, at least not for this version of RO.

However, I do invite all serious tankers to come visit Darkest Hour after our official release. We will not be running on A/B anymore...but something far better....very soon;)

EDIT: I shouldn't say "better" necessarily...I think "more advanced" is more apt.
 
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Foo'bar

FNG / Fresh Meat
Nov 12, 2007
275
0
0
Alte Ziegelei
fooblog.mexxoft.com
However, I do invite all serious tankers to come visit Darkest Hour after our official release. We will not be running on A/B anymore...but something far better....very soon;)
That does sound interesting :) Do I need to convert the AZ map to DH then? ;)
BTW: Shurek please check email, I have questions concerning VW 82.
 
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