I was considering the shaped charge, as it is used in armor-piercing munitions (ATGM, bazooka, panzerfaust, what have you), and thought of something. I have been led to believe that the shaped charge defeats armor primarily by melting/burning/cutting a hole in it using a jet of molten metal. However, what happens if something like asbestos, or other very high melting-point insulator, is put on the tank? Is this enough to reduce the effectiveness of the shaped charge?
IANAGunner, but I used to know a few. IIRC, anti-tank rounds were not only hot, but heavy and fast. That is, they were depleted uranium or some other high-density material, and they were going in excess of Mach 5. I seem to recall some hypersonic rounds, but that may be drawing board stuff.
A mundane thermal insulator like aesbestos might help with the thermal component, but it’s not going to stand up to the physical attack. The round would punch right through that layer regardless of its temperature. Some advanced ceramics might work if they provided both the structural and thermal properties required of armor.
I have not doubt that some armor is being designed, if not already deployed, to counter the rounds I was familiar with. The whole game is tit-for-tat: design a better penetrator, design an armor to counter it, design a penetrator for that, repeat until all possible funding is consumed.
Check this out:
Reactive armor is used against shaped charge weapons. It combines an angled plate with an explosive charge to dissipate the molten jet.
Here’s a decent description with good graphical representations.
http://thor.prohosting.com/~normkay/noframes/no_reactive.html
GRRR that was supposed to be Preview not damn submit. I cut off the following.
The site states that ceramics are of little value and I offer a WAG that even a several inch thick layer of woven asbestos fiber would stop a 50,000psi jet of molten copper.
IIRC, there are several types of tank munitions:
An APFSDS (Armor Piercing Fin Stabalized Discarding Sabot) or ‘Sabot’ round has no explosive charge. When the round is fired, the shell breaks away leaving a smaller depleted uranium core. That core goes something like a mile per second and smashes through armor. Anything (or anyone) on the other side of that armor is then sprayed with fragments and metal vaporized by the energy of the impact.
A shaped charge round travels much slower because it is larger than the sabot core and it doesn’t use kinetic energy to pierce the tanks armor. I think they are also used more on missles than gun shells.
To counter shaped charges, tanks are sometimes covered with explosive charges called ‘reactive armor’ that blast outward on impact. The charge disrupts the shaped charge or causes it to prematurly detonate before it reaches the tank.
http://www.aipac.org/documents/TILES.html
A mundane thermal insulator like aesbestos might help with the thermal component, but it’s not going to stand up to the physical attack. The round would punch right through that layer regardless of its temperature. Some advanced ceramics might work if they provided both the structural and thermal properties required of armor.
I have not doubt that some armor is being designed, if not already deployed, to counter the rounds I was familiar with. The whole game is tit-for-tat: design a better penetrator, design an armor to counter it, design a penetrator for that, repeat until all possible funding is consumed. **
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I’m not really talking about rounds fired from tank guns. I’m concerned only with the small shaped charge warheads used in weapons like the LAW and RPG-7. I didn’t expect any thermal insulator to stop the kinetic energy of the shell. I’m not expecting armor to be made entirely of the insulator either
I guess a better way to phrase it would be this: Is the jet of hot metal from a shoulder-fired anti-tank rocket sufficent to melt a one-inch thick layer of the best thermal insulator currently available? Assume said insulator to be over a thick steel plate or similarly sturdy backing.
It really doesn’t matter what the delivery mechanism is, the effectivenes of a shaped (or Monroe Effect) charge is determined mostly by the angle at which it strikes, the amount of explosive in the charge, and the material lining the cone (usually copper, but may be other materials).
Thermal insulators are inefficient as armor, simply because the charge doesn’t so much ‘burn’ through the target like a blowtorch, it punches it’s way through. The effect is a that of a hypersonic jet of molten copper and hot gas. It wouldn’t really matter if the charge was made out of Maxwell Smart’s Control Special[sup]tm[/sup] Cold Explosive, It’d still punch a hole in the armor, it just wouldn’t start secondary fires. It’s the mass and velocity of the jet that counts more than anything else (although secondary incindiary effects are nice, from a weapons designer’s point of view).
Various attempts at defeating shaped charges have been tried, and up to weapons of about 90mm, it’s not too tough. Beyond that, the weapon can carry more chemical or kinetic energy than can be easily defeated by conventional armor, which is where the exotic composite armors start coming into use. Stand-off armor was tried by the Germans in WWII, which was a fairly light-weight belt of armor held about 6"-10" away from the main armor. The shaped charge would hit the stand-off armor and detonate, wasting it’s jet on the air gap before the main armor. Stand-off armor was defeated by “shoulder fusing”, the practice of placing the intitiating fuse on the curve or “shoulder” of the ogive of the shell, allowing the shell to penetrate the stand-off armor mechanically before initiating the shaped charge. Reactive armor defeats shaped charges by breaking up the forming jet with a counteracting explosion. Tandem warheads defeat reactive armor by placing a small bursting charge ahead of the main charge, prematurely setting off the reactive armor before the shaped charge initiates.
The war between offense and defense continues, and it’s getting so essoteric that only the most wealthy nations can afford a large force with up-to-date armor. Everyone else has to make do with other (often ingenious) solutions.