RPG?

[-dEpRaVe-]

Not sure of where to post the question, and I tried searching but couldn't find what I wanted.

My question about military tech is about shaped-charge warheads, specifically weapons like the RPG. I know how they work and get the mechanics that operate on them, but I'm confused about how they actually destroy their targets, or if that's even their purpose.

I know that when the warhead detonates, the copper/magnesium/whatever lining is concentrated into a jet of liquid in a state of superplasticity, and that is supposed to penetrate the armor of the vehicle your firing at. My question I guess is how does that destroy/damage the vehicle? Or is the purpose to kill the crew? Because unless full-frontal penetration occured (unlikely), the jet of metal would likely only kill/injure one crew member at most, or perhaps even miss altogether. And unless it hit the magazine, that would be the end of that; a little hole in the armor with 1 casualty (more if frontal penetration is actually achieved I guess). The vehicle could still very much operate, could it not? Does the superplastic metal heat up and burn the inside of the armored vehicle like the APFSDS round does? Does it expand upon penetration? I guess I've watched too many Hollywood movies that show a tank (or even a car for that matter) go up in flames and massive explosion when it hits, but I'm wondering how tanks (or even soft vehicles like cars) start burning after being hit with a shaped-charge warhead.

Soooo, I guess my question really is: what the heck does the superplastic metal do upon penetrating armor? Thanks!

[Expendable Grunt]

Well if you hit it in the magazine it will explode, and if you piece the armour where there is a crewman, he's dead. Hit the engine and it stops moving. When you pierce the armour the shrapnel flys around inside the tank too.

[DOAW]

The actual cause of catastrophic kills, the ones you see where the whole tank explodes and turrets fly into the air, is the warhead detonating the fuel and ammunition in the tank.

[RittWitt]

The easiest answer to this is what has already been stated. A shaped-charge does not destroy a vehicle outright. The "jet" is simply designed to penetrate the armor in a small place, and is one of the most effecient ways to do short of a super-velocity kinetic energy round like the sabot from another tank. The damage to the vehicle is largely dependant on the type of round versus the type of vehicle. A PG-7 grenade versus an Abrams (or other modern tank utilizing reactive armor) is neglible as it will almost certainly not penetrate into the interior of the vehicle. However, a PG-7 versus a light-skinned vehicle like a HMMWV or BMP will cause catastrophic damage to the crew of the vehicle. When the jet itself penetrates the interior wall, it essentially stops. What does the damage is a "spalling" of material on the interior side of the wall that is a flying cloud of sheared metal from the vehicle itself and the rapidly solidifing molten mateiral from the "jet." This shreds crewmen in the event of a crew hit, and will literally detonate HE type rounds in a magazine hit. The same effect can be acheived against a heavily armored vehicle by using a larger sized warhead, such as a HEAT round fired from another tank. The weight of the charge is directly proportional to the penetration of the jet. More HE=more penetration. Hope this answers some of your questions.

RittWitt

[ZephyrDraevyn]

As the saying goes, "There's more than one way to skin a cat." Well, there's more than one way to kill a tank/armoured vehicle with an RPG.

It all depends on how we consider the vehicle's state after the RPG has hit it.

• Can it still move ?
• Can it still fire it's weaponry ?
• Is it still inhabitable by the troops ?

If the answer is 'no' to any of these, it's effectively a 'kill' of the tank/armoured vehicle.
Can it move? : If not, it can't evade the next shell that's probably already incoming.
Can it shoot? : If not, it's not much use to the troops, although it could run for friendly lines and hope for a repair.
Can troops get in it : If the crew compartment of an APC is shredded / on fire / has sharp pointy bits of metal sticking out from every surface / sealed off coz the rear doors are jammed solid by damage, it's useless as a transport.

A 1/2" hyperaccellerated jet of superplastic copper can cause any one of these effects if placed in the correct area... and could conceivably cause multiple effects at the same time :

RPG @ APC from the rear. It penetrates the rear crew compartment doors, jamming them solid. Heat from the superplastic metal causes fire in the crew compartment, with the kinetic element of the shaped projectile travelling the length of the APC, killing the driver and cooking off some of the ammo for the 30mm cannon. The ammo detonations kills all of the crew.

The hull of the APC holds, but to all intents and purposes, it's dead. It has ceased to be of any use on all accounts - you cant get in/out of it, it can't move, it can't shoot, and nobody inside it is still breathing. About the only thing you -can- do is hide behind it from the outside, and even then, with a fire inside, it's going to get hot, quick, acting like a beacon to anyone with FLIR / Heat sensing equipment.

It doesn't even have to utterly destroy, say, the engine block to kill the vehicle either. Sever electronics, cut throttle/clutch cables, rupture fuel lines, crack the block, shear off the overhead cam.... all of these will effectively stop a vehicle moving.

A RPG detonating off the end of a tank barrel has a high chance of it stopping the tank from firing... the last thing a tanker would want is for the shell he's just fired to cause more damage to the barrel by jamming / overpressure ballooning etc.

It's all relative

An RPG is also useful against other targets with the effect of halting / impeding vehicles :
RPGs -v- Trees, laying them across roads.
RPGs -v- Runways, making them useless for landing fast jets (true, you'd need a lot of em to do this, but it'd work)
RPGs -v- Bunkers, and hope that the shaped charge has enough energy to defeat the 12-18" thick walls of concrete/sand/whatever.

And finally, the sick one

RPG -v- human : Chances are, unless it hits hard armour (ceramic/steel/kevlar plate) the shaped charge isn't going to detonate. However, the projectile does weigh about a kilo, it's pointy, and it's doing a fairly respectable speed. If it does detonate, well, results will be messy, as there's no way a human body could resist the force of 3/4 kilo of explosives detonating against his/her chest, with a molten superplastic copper dart punching a 1" diameter hole clean through.

[Hardtman]

I thinks you got one bit wrong,the Copper(or Uranium,hell,even Gold would work) is in no point of the detonation actually molten, the deformation os a cold one,meaning only archieved by force used onto the solid metal.

So,everything has been said about how it works, don't forget,it punches to many,many layers of usual tank-steel-plating:



So it will probably hit something vital inside,be it spare ammunition,the engine or simply a crew member.

But I wonder about one thing: You shoot at an APc movin perpendicular to you. And you are an a**hole(),because you shoot at the back area, where the transported people are located. Assuming it does not hit anybody inside because they are only sitting close to the front or w/e, could the dart actually pass through the whole cabin,leaving only a 5cm diameter hole and doing no further damage?

[mrmong]

the pressure would blow the inside up and make it very nasty inside

[Lampshade111]

What sort of ammo are you talking about there?

[ZephyrDraevyn]

Originally Posted by Hardtman

I thinks you got one bit wrong,the Copper(or Uranium,hell,even Gold would work) is in no point of the detonation actually molten, the deformation os a cold one,meaning only archieved by force used onto the solid metal.

Take a strip of alumininium and flex it back and forth - it'll heat up. Using a quantity of explosives to forge a long thin dart from a disc will temporarily melt it, but it will quickly cool back down to create a cone-shaped projectile.

Originally Posted by Hardtman

But I wonder about one thing: You shoot at an APc movin perpendicular to you. And you are an a**hole(),because you shoot at the back area, where the transported people are located. Assuming it does not hit anybody inside because they are only sitting close to the front or w/e, could the dart actually pass through the whole cabin,leaving only a 5cm diameter hole and doing no further damage?

In theory, yes and no. Assuming that the explosive spalling (http://en.wikipedia.org/wiki/Spall of the self-forging projectile / armour plate as it passes through misses anything inside, there's still the several hundred cubic feet of rapidly expanding hot gas from the explosive detonation, so that's going to cause all manner of injuries to the folk inside the APC, including ruptured eardrums, shockwave-based damage, burns etc etc etc. There's also the appropriately named 'chunky salsa' effect due to the rebounding of the explosive shockwave within the confines of the APC (assuming that it holds)...

What sort of ammo are you talking about there?

Whilst not being entirely sure of the internal composition of an RPG, we're talking about a rocket-projected shaped charge with an explosively formed penetrator. These links are helpful.

http://en.wikipedia.org/wiki/Shaped_charge

http://en.wikipedia.org/wiki/Explosi...med_Penetrator

[RittWitt]

I just want to clarify something here:

Whilst not being entirely sure of the internal composition of an RPG, we're talking about a rocket-projected shaped charge with an explosively formed penetrator. These links are helpful.

http://en.wikipedia.org/wiki/Shaped_charge

http://en.wikipedia.org/wiki/Explosi...med_Penetrator[/quote]


This statement is incorrect. A RPG (Rocket Propelled Grenade) does not use an explosively formed penetrator. I'm not making a blanket statement to the effect that there are *no* RPG type weapons that use one, just that most do not. The generally pictured RPG is the PG7, a Soviet weapon that utilizes one shaped charge. A shaped charge penetrates the armor of its target with a super-plastic jet. An EFP, on the other hand is entirely different in that it utilizes a physical projectile traveling at hypervelocity to do its work. This effect can be most easily equated to the penetration one sees from a sabot round fired from a tank. There is no explosive reaction involved once the penetrator is launced. All the pentration is done via kinetic energy delivered to the target, and the EPF will sometimes continue to travel inside the vehicle, whereas a shaped charge will dissapate immediately upon breaking through the armor of its target.

To give the layman an idea of what I mean when I say hyper-velocity, I will give the following example. The wikipedia article on EFP's quoted above states that the liner formed travels in excess of 1km/sec. That's faster than the speed of sound. Even at a very close range of 5-10m, that effectively means that by the time the blast wave (sonic energy) reaches you, the liner will have already penetrated your vehicle, spalled massive amounts of material from the entry area around the cabin, torn through (and generally apart) any crewman in touches or comes in close proximity to, and continued out the other side of the vehicle if it has remaining energy left. Basically, you'll never know what hit you.

I hope I didn't offend you by correcting your post, Zephyr, but I just wanted to make this difference clear. It's a common mistake because the effects seem to be generated from similar circumstances, but are in fact, quite different. Both are extremely deadly.