Calculating Armor Penetration

[Purple]

I am looking for a way to calculate the penetration of bullets and small scale direct fire artillery weapons (tank cannons, Gatling guns and the like).

I tried searching for it and came up with this thread: link. But after reading it I determined that it contains no data that I can viably use (baring some interesting points on materials used).

Saying this, I am new and did not know the exact policy on posting on 3 weeks old threads so I thought it best to post a new one.

In essence, I am looking for a formula that would help me determine the penetration of a direct fire kinetic projectile made from materials with known properties into armor made of materials with known properties flying at speeds between high subsonic (Mach 0.7-0.8) to moderate supersonic (Mach 5-7, comparable to 2-3 times the speed of a 7.62mm39 AK round).

The formula would do ideally to abstract the angle of impact (assumed to be 90 degrees into a flat armor plate) and require no external value tables.


Thank you in advance for all your replies.

[Darth Wong]

There's lots of information on navweaps.com, at least pertaining to naval guns and armour. As a general principle, something like this is going to be determined based on empirical data tables and correlations drawn from them, rather than deriving it from first principles.

[Purple]

Thank you, I am aware of that. However, I am sadly unable to acquire a gun and test fire it to determine the data I need.

I will look up the web site however I really need a way of calculating the data my self.
I am working on a text RPG in another forum (limited to todays technology) and I am doing some experimentation with different projectile types (material/shape/etc.) as well as mass vs velocity. In particular, how would different types of penetrators fare against tank armor.

I did not want to post this into the SF forum since, even thou it is essentially drawn toward fiction I do not want to be drawn into speculations about SF materials and weapons (rail guns, diamond bullets, durasteal plates and what not).
I hope I did not make a mistake there.

[Darth Wong]

That's OK. Perhaps this link will be more to your liking:

http://www.battlefield.ru/en/articles/3 ... armor.html

[Purple]

Thank you. That seems to be what I am looking for.

The only thing is that the formula in question refers to something called "weighted coefficient of the durability (AP resistance)".
To quote the full line:

K -is the weighted coefficient of the durability (AP resistance) of the armor and the construction of the projectile. Before the war K values ranged from 1900 to 2300.

However, I can find no link to said table.

I tried checking it on wikipedia and the closest thing I found was durability/impact resistant => Toughness. But the units (J/m^3) do not match those that would be required based on the penetration formula (m/s * Kg). I did not expect they would but had to try.

Can you give any advice as to what values I should use? Should I just go for the maximum 2300 as a safety? Since google is not providing me with any meaningful output either.

[Marcus Aurelius]

I am looking for a way to calculate the penetration of bullets and small scale direct fire artillery weapons (tank cannons, Gatling guns and the like).

I am not trying to belittle this site or Mike's considerable engineering knowledge, but you might have more success asking this at the Tank-net.org Armor Scientific Forum. They have specialists like Willi Odermatt. You might also find his calculator useful; you can find it on the pages linked to his name. (I will not write his username here, but it's easy enough to find on the forum itself; he's not really trying to hide his real name.)

Just remember that most of the people there care primarily about the science or using the things for real and not so much about gaming, although they do have a Gamer's Forum as well.

[Darth Wong]

Don't worry, I wouldn't take any offense. I never specialized in weapons and armour; I did study fracture mechanics, but in the context of normal structural loading. Armour penetration is a particular specialization which is not relevant to most mundane mechanical engineering.

[Purple]

With the second page I completed the part on Tank cannons.
Thank you.

However I still need to calculate the values for solid bullets.

Using the formula given by DW I got an idea and I need someone knowledgeable to tell me if my logic is valid.

Here it goes:
Since the K is a factor taken for the material of the armor and round in question. I assume that the material in question for the armor is steel. I also assume that since the numbers presented there are for large rounds (artillery shells) I could use known penetration values for objects like AK47 rounds and work out the K factor in reverse. (I would use several values and take the average)

Than I could apply said factors to the calculation to get a fairly approximate value for penetration. With a slight safety (say 20%-100%) I could use this calculated value when calculating bullet penetration.

Note that for bullets I do not need particularly precise values and that as much as 10-20% off in any direction is fine.


Is my logic any good?

[RRoan]

To be honest, RHAe penetration values aren't a ton of use these days as anything beyond a general idea, considering the wide variety of different ways that various tank armor components and armoring schemes work.

[The Duchess of Zeon]

The Nathan Okun section of Warships1 is somewhat hidden, so if you didn't see it before this is what you want to look at

With his other separately held articles of: Notes on modern armour, and Defeating face-hardened armour, also being very useful. I would have never studied engineering without nerding out over this stuff while growing up, so if you have any questions... But the answers are strictly from the standpoint of a hobbyist still working on an engineering degree.