Hull damage?

[Larry Holt]

There has been some frustration in this forum over the issue of penetration without damage on tanks. I understand the conditions that this may occur without damage to one of they systems modeled in the game but I wonder why there is no "hull damage" at least. I often see "thru and thru" hits where penetration is in excess of twice the armor thickness but no damage message. I interpert this to mean the round went in one side and out the other but why no damage? Clearly having holes in your hull is "damage" in the dictionary sense of the word so does hull damage in the game have some special meaning? In particular I know that accumulated damage increases the chance that a crew will involuntarily bail out so penetrations without damage don't seem to add to this risk but I think that they should.

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An old soldier but not yet a faded one.
OK, maybe just a bit faded.

[Paul Vebber]

IF a tree falls on tank in the forest...?!?


The game uses a rather abstract "effects-based" damage model. The game models two types of impacts, one that only has the potential to damage exterior systems (and rattle the crew) and ones that have the potential to damage both exterior systems and interior systems. Based on the Vehicle size and survivability, and the warhead size and "excess penetration" a percentage is determined, and each system is "diced for" based on this percentage. If its a big shell with lots of ommph vs a small target, the percentag is high, and after rolling against 5 or 6 systems, something generally happens.
IF a round hits a large survivable target, then the percentages are smaller and probability of "no effect" is higher.

IF a system modeled in the game isn't damaged, then there is "no damage". We tried to get more complicated, but it was very buggy...

IF a "Penetrating hit" does nothing, it could be for a number of reasons beside going "through and through". The armor could have simply "cracked through" (particularly if it only "just penetrated". It could have penetrated into an "edge" or a location where its damage would be longer term (say holing a lube oil tank that may cause the engine to seize up later...) or caused damage to a system the game doesn't model, OR it "coulda,shoulda" penetrated, but due the vagueries of ballistics, it didn't...maybe shattered or just deflected funky in the midst of penetrating...

But the bottom line is, the target "made" all its rolls for each system... Generally in the 20-40% range for 4-6 systems depending on the location hit. (the odds of "making" 4 20% rolls is about 40%, while the odds of "making" 6 40% rolls is about 5% so that is teh general range of likelihood of "nothing happens" results based on teh factors).

The enterpretation of how that happened is left to the player

So a penetrating hit is not necesarily a round bouncing around inside, and 'damage' is purely damage to systems the game represents. Tracking "accumulated damage points" is something we looked at, but would take too long to implement for the amount of improvement it provided.

[gdpsnake]

In reality, if a round passed through a tank the crew would be 'jellied' by the shock of the passage. The shell shock wave is incredible. I remember a story of a King Tiger getting hit by a 90mm allied AT shell. When they looked inside, the crew was just black smears with rags on.
I also got a trip in a British centurion and the tankers told me the same thing. A penetrating shot is a kill even if it doesn't explode. If the shell has enough power to punch through a vehicle you're dead!
I think of the rounds in the game as exploding on the outside maybe even make a hole but don't quite get through because of angle and blast effects. Stuff happens. A helo jock in 'Nam got shot in the side of the helmet on the right temple. The bullet exited the left side of his helmet by his left temple and went out the windscreen. The guy thought he was shot straight through his head but when he got home and they managed to talk him into taking off his helmet, the bullet had hit his right temple bone and deflected to the back of the helmet where it left a crease all the way around the back of the helmet to where it hit him in the left temple and deflected out the left side of the helmet! Talk about luck!
Anybody else have actual data/stories on tankers surviving a shell that passed through?

[Larry Holt]

Originally posted by Paul Vebber:
...Tracking "accumulated damage points" is something we looked at, but would take too long to implement for the amount of improvement it provided.

I thought that the damage points in the unit screen did reflect accumulated damage? Isn't there some accumulated damage statistic that increases the crew's chances of bailing out?
I've read the ordnance reports on ballistics and I realize that while AP rounds may have the energy to penetrate, they may break up and not do so however the screen reports penetration in excess of armor thickness. It seems to me that if the target survives its rolls and avoids hull damage then the penetration message should say "no penetration" or "no effect". Alternately if there is complete penetration then perhaps that should overrule any hull damage roll.
The current messages (penetration but no damage) conflict. Either way it could be resolved (suppress penetration messages when no damage roll is made or overrule damage roll when penetration is calculated).

Then again I could just thank you for a great game and drop the subject as being too much to put in the game.

Thanks.

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An old soldier but not yet a faded one.
OK, maybe just a bit faded.

[BA Evans]

Originally posted by gdpsnake:
In reality, if a round passed through a tank the crew would be 'jellied' by the shock of the passage...

Would this be true if the penetration occurred in the engine compartment? The crew compartment would still be intact.

If the shell penetrated the engine compartment but didn't have enough power left to penetrate the engine block, it is possible that all you would have is a hole in the tank and a few marks on the side of the engine. The engine might start running rough two days after the battle and need to be repaired.

It is also possible that you could penetrate the engine compartment, miss the engine completely, and then go out the other side of the armor. Here you would have a very powerful shell penetrate with lots of power, but not damage anything.

Also judging from battlefield reports, it took many hits to destroy a tank. When you look at only penetrations you needed to average more than one penetration to destroy a tank.

The tanks in SPWAW might be a little more survivable than real life, but they are not that far off. The only problem I have found is when you fire at a tank within 3 hexes that is higher than you are. I seem to get tons of bounces and/or massive armor values. Thus, they become almost unkillable.

BA Evans

[gdpsnake]

I've had the same thing happen only downhill as well. I was higher than the enemy shooting while he was downhill! You think with the top exposed a kill would be easy BUT I hit him dozens of times at 99% with 88mm AP and APCR shells (T-34 target) and never got ANY result but bounce or ricochet. I think the 'hull down' code is not working right or the routine that offers protection to a target at different elevations is in error.

[Paul Vebber]

Sorry - I thought you meant accumulating damage from hits in general. Damage "stars" - representing failed "damage rolls" - do accmulate. This is what the "damage" number in the unit status screen represents.

Penetration is a stochastic event. If you take a round that "penetrates" 50mm, then depending on the definition of penetration used, if you fire it at a 50mm plate 100 times 50% (ballilistic limit velocity definition) to 80% (reliable velocity definition) will actually penetrate.

And depending on the methodology, "Penetration" can range from a through crack, to deformation of a soft backing plate, to complete projectile passage. "Book values" typically don't tell which of these criteria they are talking about.

Now teh averaging that we do maeans the penetration in the game is something in between - about a 70% chance of backing plate deformation. THough this varies with target size and survivabilty and warhead size and "energy".

Think about "penetration" as an energy and "armor" as the resistance to that energy and the difference being effectively a probability that the energy will overcome the resistance. A low differnetial means a "base chance" while an increasing difference means a greater and greater probability (though the max is capped at 95%)

The message "penetrates" means the energy is such that the "penetrating round" damage routine is used, if non-penetrating then the other damage routine is used.

We originally intended to remove those messages (as they were meant for debugging purposes only) but the playtesters liked it so we leaft them in. They are not meant to be taken literally. THe front 10mm of a shell tip is not sticking through the armor if the pen-armor = 10mm

[Scipio Africanus]

Hi BA, I don't think that getting lots of bounces or high armor values when firing at short ranges at a target which is above you is a problem.

First of all the target is hull down so you can only consider the turret armor.

Second, the angle of firing is added to the armor angle of the turret- so if you're firing up a 20 degree slope at something with 30 degrees of turret/superstructure armor you've suddenly got 50 degrees of slope.

Slope does a lot of nutty things to the ballistic equation. For example: 120mm of armor has a real thickness of ~168mm at 45 degrees aspect,and the effect increases geometrically (not in a strictly mathematical sense, but it is a useful analogy) with the increase of angle; thus 120mm of steel has a real thickness of ~315mm at 67 degrees.

But this isn't the whole story of course. For while the velocity of a shell is a constant that decreases only with a loss of energy (such as the friction of air, earth, or steel), this velocity is only at its maximum in relation to a plane perpendicular to its line of travel. Thus, the velocity of a shell moving 1000 meters per second projected onto a perpendicular line extended from a plane (the armor) canted away from the line of travel of the shell by 45 degrees is only a little over 700 meters per second along the projected perpendicular line- nearly a 30% loss in energy just from angle- at 67 degrees the velocity of our shell along the perpendicular is only ~350 meters per second.

So angles both make the armor thicker and reduce the energy of a shell in relation to the perpendicular line drawn extending from the plane of the armor. So, excluding turret edge hits, which at decent angles should result in several meters of armor, I would suggest that ultra high armor ratings are taking into account both the added geometrical thickness of the armor at angle, and the loss of efficient shell energy- and since they don't tell us shell velocities on hits, it's likely that this factor is included in the high armor ratings.

I don't know for sure how SPWAW works in this regard, mine is simply the physics explanation which works in the real world.

Cheers,

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Publius Cornelius Scipio Africanus

[Scipio Africanus]

Just to clarify- a shell moving 1000 meters a second is still moving 1000 meters a second- just not at the plane of armor that is tilted away from it. Directly at such a plane of armor (perpendicular to it), relative velocity is reduced by angle -if you like, envision the line perpendicular to the plane of armor as the base of a triangle and the line of the shell path as the hypoteneuse. Since the hypoteneuse of a triangle is always longer than its base (unless it's equilateral or isoceles, but ours necessarily isn't), if both base and hypoteneuse are drawn in the same amount of time, the base is necessarily moving more slowly than the hyp. Since the base of the triangle is the line perpendicular to the plane of our armor, the relative shell velocity is reduced- it's still moving 1000 meters per second, just not directly at the armor.

Ah well, I use Rangers to blow up tanks anyway



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Publius Cornelius Scipio Africanus

[fdlu]

Just to ask:
can somebody list the different damage
events(track hit, optics, tool box etc.)
and discribe their effects ??
I haven´t found it explained anywhere.
track hit is mobility kill,
radio mast is no radio ??
..... ?
is it possible to access the kind of damage on a specific vehicle afterwards ??
there are "damage: 4 ", but i do not now
the specific damage if i hadn´t noted it on
paper.

[Paul Vebber]

An interesting way of looking at it SA!

A couple points though. Its the component of the force exerted by the armor on the projectile in the plane of the armor, not the velocity component of the projectile that is important. I that force is sufficient to change the direction of the projctile before it displaces sufficient mass of material, the round richochets.

Now that force is applied to one side of the projectile, so the projectile begins to rotate. If the projectile rotates sufficiently that the curved path it follows exits the armor, a "glancing strike" that only partially penetrates (and in game terms is the same as a richochet) results and teh projectile fails to defeat teh armor.

Now the diameter of that curved path is a function of several variables, and there is also a "critical velocity" based on shell characteristics and armor hardness that can cause the shell to shatter instead of do either of the above.

So the "ballistic effective thickness" or the length not of the "geometric line" through the armor, but the length of the curved path through the armor material is the REAL distance teh projectile must travel to penetrate. This diameter is a function of "T/D ratio" or the thickness of the armor divided by the Diameter of the shell (among other things).

So a 120mm plate at 45 degrees is effectively not 168mm thick but 120/cos(45)^1.6 (using Ogorkeiwicz's approximation form Jane's "Tank Design") or 209 mm. 120 @ 67 is actually ~540mm. But at again the efect of T/D means that there is a high probability that such a round will ricochet or 'glance off" scouring the armor as if someone drew and ice cream scoop through the plate (such strikes can be seen on vehicles at Aberdeen proving grounds Tank Museum)

I think using a decomposition by force vectors, rather than velocity vectors is a better way of looking at the problem.

The point is valid, though that "effective" armor thicknes is a very complex thing and even the fairly sophisticated model we use only scratches the surface of the problem.

Firing up or down at close ranges exacerbates teh problem by increasesing what are already high slope values. That is why we added teh "bottom" hit as a way to account for unique exposures of shot traps and vulnerable areas when firing up at close range. Firning down typpically devrease armor slope seen and decreases protection, though the "die rolls' can still get you.

Version 3 improves this modelling somewhat by adjusting penetration, and T/D ratio modifiers a bit.

BT -- new subject -- damage

The manual describes the teh damage types, teh way to know they have occurred is to look at teh change in stats. If you FC is suddenly 0 you took an "optics hit" if your speed is halved or quartered you took one or more suspension or engine damage hits. IF it suddenly gopes to 0 then your engine ior suspension is disabled. Guns will "go away" based on damage or malfunction, and in version 3 can be repaired sometimes. Crew casualties will show by a reduciton in men and a loss of ROF. etc.

[Larry Holt]

See: http://www.wargamer.org/GvA/index.html for a good tutorial on the subject or projectile vs. armor.

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An old soldier but not yet a faded one.
OK, maybe just a bit faded.

[Paul Vebber]

Yes, I am patiently awaiting Livingston and Bird's book on the subject whic I think some of that materiel is a preview of!

[Scipio Africanus]

Now that is very cool Paul. I guessed you would chime in if I started throwing some math around

I had not considered the deflection of the shell path on impact with the armor plane- my geometry is nice linear/planar Euclid and Archimedes, your geometry is post-Newton/Descartes- I lose -of course the path deflection results in a nice funky curve projected through the plane of armor- that makes sense. Very sophisticated and very cool that it's in the game. SPWAW and its design team continue to impress...

Also, I liked the preliminary posting of unit values for ver 3 that was up the other day- looks good.

Cheers,

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Publius Cornelius Scipio Africanus

[Dave R]

I've got to say Paul, this is one system that just doesn't hang true for me. I'm regularly seeing tanks survive anything upto half a dozen penatrating shots with little effect! I could live with the odd 'pass through' lucky shot for the crew, but not on the scale that it seems to be happening. I feel that this is something that should be the exception rather then the rule, and more common in the earleir days when there was usually penatration shots from smaller calibur weapons, and certainly not from an 88 shell! I've just had a Russian BT something or other survive 4 hits from an 88 and all apearing to be pass through shots!I just feel this is the one poor, unrealistic system in the whole barrel of wonderful systems that make up the game

[Paul Vebber]

The problem is the message boxes use of "penetration" and armor that invites a direct comparison of values that imply a "penetration" occurs when it may not.

100 pen vs 99 armor implies that the round "penetrates" when this is not necessarily the case. The pen being greater than the armor means the round HAS A CHANCE to penetrate, and the chance gets bigger with the "energy" differential. Rember that "book values" of penetration are typically based on "ballistic limit velocity" that mean that the round has a 50% chance to penetrate. Gamers tend to think in terms of absolutes and that a round with 100 penetration "always" will penetrate a slab 99mm thick.

This is not the case.

Now as to 88s vs BTs - there was a problem with the T/D table not going down low enough to give the right answer - this has been fixed in version 3 and is a pronblem with the penetration routine - not the damage routine.

The other problem is that the survivability numbers of many vehicles was not correct so they were much more prone to shrug off penetrating hits than they should.

That we will still be working on improving after version 3 (with a partial fix) is out.

The whole armor penetration problem is a very complex one that even the system we have only scratches the surface of.

The most important thing to remember is that you have to think of penetration not in absolute terms but as probabilities. If you have a penetration of 200 vs an armor of 50 then there could still be "extenuating circumstance" a supporting beam, a tow point, a hatch coaming etc that can cause a round to fail to "penetrate".

Gamers are used to "absolutes" in penetration issues and while there are rough edges" to the present system, it tends to be more right than wrong.

(And if anyone noticed CM recently increased the front turret armor of its Tigers in ver 1.05



[This message has been edited by Paul Vebber (edited August 26, 2000).]