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Metal foam obliterates bullets

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Re: Metal foam obliterates bullets

#51

Post by InclinedPlane »

PhantomGremlin wrote: post #18
patio11 wrote: post #11

Earlier quoted context omitted.

It's going to be expensive, may not meaningfully improve survival in actual combat situations, and may not actually be successfully deployed. How could this be extraordinarily effective at stopping bullets but not meaningfully improve survival? Fairly few American soldiers are killed by gunfire which directly strikes them; even fewer of these soldiers are killed by gunfire which directly strikes them on their armor.…

What about vehicle armor? Something like this would be a great improvement over the very heavy homebrew plating that our guys in Iraq and Afghanistan were forced to improvise on their Humvees? I.e. before MRAP type vehicles made it into the field. Lighter and better armor isn't just for people, it's also for vehicles.

It's actually very similar in a lot of ways to chobham armor, which is layers of ceramic and high strength metal in a composite structure. This seems to work similarly but with a more consistent mixture of both materials throughout a material, which might make it easier to manufacture and to work with, and possibly lighter as well.

Re: Metal foam obliterates bullets

#52

Post by refurb »

spatulan wrote: post #49
refurb wrote: post #20

Earlier quoted context omitted.

I thought the slats were to provide stand off distance for explosively formed projectiles. If the explosively formed jet forms more than a few inches from the armor, it's way less effective.

That's backwards. Explosively formed jets need space to form, so work better if they detonate a little distance from the target.

No, you're right. Explosively formed projectiles work best when formed a few inches from the armor. However, they have a sweet spot and if the distance is too far, they don't work. I figured that's what the cages were for.

Re: Metal foam obliterates bullets

#53

Post by zardo »

spatulan wrote: post #50
SEJeff wrote: post #19

Earlier quoted context omitted.

This is exactly how a Soviet style RPG works. Ironically, it is also why the "bird cage armor" works so well against the RPG. Here is a picture of a Stryker combat vehicle from when I was in Mosul Iraq circa 2004ish: http://www.digitalprognosis.com/album/images/iraqpics/the-st... The slats are smaller than the height of the outer explosive and prematurely detonate it. As a result, the penetrator simply bounces off th…

I though slat armour worked because RPGs only had a detonator in the nose, so unless you were very unlucky and the tip of the RPG hit a slat, the RPG would just jam itself between two of the slats.

Then they make the new guy get them out with a pry bar.

Re: Metal foam obliterates bullets

#54

Post by hga »

PhasmaFelis wrote: post #32
kibwen wrote: post #3

Neat, though of course this raises the question: what would it take to engineer a foam-piercing bullet?

I'm not an expert, but after some Googling, I think the bullet they're using there consists of a steel core inside a lead envelope inside a copper or copper-nickel jacket. So, at a guess, you'd want to replace the steel with something much harder and/or denser. Tungsten, maybe? I dunno. Depleted uranium would probably do it; I've never heard of it being used in anti-personnel rounds, but in cannon sizes it pokes hole…

Indeed. The AP M2 round is the standard for National Institute of Justice (NIJ) Level IV rifle plate armor, but to the best I've been able to determine it's not a "serious" AP round, rather, it has a pill of relatively soft steel inside the normal lead and was developed in the run up to our involvement in WWII as much for the lower cost as the increased penetration. The latter of which was appreciated towards the end of WWII when I've read it became ubiquitous, and for example in city fighting one or more 20 round BAR magazines of this were used to knock holes in masonry walls between buildings.

It was probably made the NIJ standard because it's the only somewhat common AP ammo a US cop is likely to go against on the street, as noted by extrapickles the serious AP ammo is a lot more expensive, and I'll add not really legal any more since there are some pistols that'll fire it.

Notably, ESAPI military equivalent plates also aren't certified to stop anything more serious than AP M2, and I assume again for the same reason, there is or was a lot of surplus AP M2 ammo out there at one time. In the US civilian marketplace it's pretty much dried up as I understand it, e.g. see the few hits this GunBroker.com search finds and the prices: http://www.gunbroker.com/Ammunition/BI.aspx?Keywords=ap+m2 and I can't find any demilled bullets there or with a couple of minutes of Google time, whereas they were commonly available not too many years ago, certainly within the last decade.

Re: Metal foam obliterates bullets

#55

Post by redacted »

I did modelling work for a group researching metal foams in my past academic life. Very interesting stuff with a lot of applications if the manufacturing processes can be nailed down.

Our funding was a mixture of European Space Agency and a car conglomerate: light armour for space vehicles and crumple zones / reinforcement respectively (less acceptable to research military applications in EU in my experience).

Re: Metal foam obliterates bullets

#56

Post by chillydawg »

dkbrk wrote: post #29

This doesn't have much in the way of interesting details, you need to go to the paper for that. The armour is a composite sandwich, with boron carbide on the front face (a hard ceramic), followed by the metal foam, and either aluminium or kevlar on the rear face. The boron carbide layer blunts the bullet and distributes the compressive stress over a large area of the metal foam. The metal foam is made of 2mm-diameter…

Presumably very expensive and one-time usable. I guess that's true of most types of armour anyway.

Re: Metal foam obliterates bullets

#58

Post by awalton »

blisterpeanuts wrote: post #14
kibwen wrote: post #3

Neat, though of course this raises the question: what would it take to engineer a foam-piercing bullet?

Two projectiles. First one explodes on impact and compromises the target. Second one penetrates the target.

...which is already defeated by reactive armor, which you'd presumably layer underneath this ablative mesh armor layer to prevent this kind of attack.

So, three projectiles in the same spot?

Re: Metal foam obliterates bullets

#59

Post by dexterdog »

awalton wrote: post #58
blisterpeanuts wrote: post #14

Earlier quoted context omitted.

Two projectiles. First one explodes on impact and compromises the target. Second one penetrates the target.

...which is already defeated by reactive armor, which you'd presumably layer underneath this ablative mesh armor layer to prevent this kind of attack. So, three projectiles in the same spot?

Better start with four so you're ready for the next shielding upgrade.

Re: Metal foam obliterates bullets

#60

Post by coldtea »

chillydawg wrote: post #56
dkbrk wrote: post #29

This doesn't have much in the way of interesting details, you need to go to the paper for that. The armour is a composite sandwich, with boron carbide on the front face (a hard ceramic), followed by the metal foam, and either aluminium or kevlar on the rear face. The boron carbide layer blunts the bullet and distributes the compressive stress over a large area of the metal foam. The metal foam is made of 2mm-diameter…

Presumably very expensive and one-time usable. I guess that's true of most types of armour anyway.

>and one-time usable

It's not like you want it to save your life more than once...

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