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Metal foam obliterates bullets

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Re: Metal foam obliterates bullets

#41

Post by PhasmaFelis »

dredmorbius wrote: post #35
PhasmaFelis wrote: post #33

Earlier quoted context omitted.

If you can reliably hit a target that small, you could just shoot the other fellow in the eye and not worry about armor.

No. You're confusing consistency with accuracy . To hit someone in the eye, you've got to aim at their eye and land a round there. That is, accuracy at hitting a pre-specified target. To hit armour in the same location twice, you need either two (or more rounds) delivered consistently on whatever happens to be where the first round lands . It's a case where being a Texas Sharpshooter actually works (painting bullseye…

At that point, wouldn't it be easier and just as effective to use a single, larger round? .50-cal rifles already exist; no need to invent a big bullet that turns into two smaller bullets.

(Unless you mean something that starts out the same size as the one in the video, in which case I can't imagine that two halves of a .30-06 would penetrate any better than one whole .30-06.)

Re: Metal foam obliterates bullets

#43

Post by dredmorbius »

PhasmaFelis wrote: post #41
dredmorbius wrote: post #35

Earlier quoted context omitted.

No. You're confusing consistency with accuracy . To hit someone in the eye, you've got to aim at their eye and land a round there. That is, accuracy at hitting a pre-specified target. To hit armour in the same location twice, you need either two (or more rounds) delivered consistently on whatever happens to be where the first round lands . It's a case where being a Texas Sharpshooter actually works (painting bullseye…

At that point, wouldn't it be easier and just as effective to use a single, larger round? .50-cal rifles already exist; no need to invent a big bullet that turns into two smaller bullets. (Unless you mean something that starts out the same size as the one in the video, in which case I can't imagine that two halves of a .30-06 would penetrate any better than one whole .30-06.)

There's often an advantage do a dual-mode strike. That's how many existing armour-piercing weapons operate. E.g., tungsten-alloy armor piercing rounds:

http://www.tungsten-alloy.com/armor-piercing.htm

Another alternative, depleted uranium, relies on the exceptionally dense, and self-sharpening DU penetrator to defeat armour. Rather effectively.

Re: Metal foam obliterates bullets

#44

Post by M2Ys4U »

hyperion2010 wrote: post #9
ceejayoz wrote: post #5

> Last year, with support from the Department of Energy's Office of Nuclear Energy, Rabiei showed that CMFs are very effective at shielding X-rays, gamma rays and neutron radiation. Designers of spacecraft and lunar/Mars bases are likely pretty happy about this development.

Here's the doi for that paper: doi:10.1016/j.radphyschem.2015.07.003 Unfortunately I could only find the paywalled version here: http://www.sciencedirect.com/science/article/pii/S0969806X15...

Try putting the DOI into sci-hub.io

Re: Metal foam obliterates bullets

#45

Post by venomsnake »

colordrops wrote: post #7

Would this be effective against micrometeoroids and orbital debris?

The current designs already use dual hull - the first makes the projectile explode to dust, the second stops the debris. The critical problem is weight. That construction that is shown looks to be quite heavy relatively.

Re: Metal foam obliterates bullets

#46

Post by matheweis »

paulsutter wrote: post #34
colordrops wrote: post #7

Would this be effective against micrometeoroids and orbital debris?

I asked Dr Rabiei that very question by email yesterday, and she is working on it: "Let me start by saying that it is not a crazy idea and is actually what I have been working on recently. I even have a proposal in DARPA on testing the performance of the material at supersonic speeds. At this time, our data covers up to a speed close to 1Km/s as you mentioned. We have not tested the performance at higher speed and th…

That would be outstanding if it could ... talk about the perfect material for shielding supercritical spacecraft components. Radiation resistance, projectile resistance, lighter than normal metal, temperature resistant... What's not to like?

Re: Metal foam obliterates bullets

#47

Post by AaronFriel »

matheweis wrote: post #46
paulsutter wrote: post #34

Earlier quoted context omitted.

I asked Dr Rabiei that very question by email yesterday, and she is working on it: "Let me start by saying that it is not a crazy idea and is actually what I have been working on recently. I even have a proposal in DARPA on testing the performance of the material at supersonic speeds. At this time, our data covers up to a speed close to 1Km/s as you mentioned. We have not tested the performance at higher speed and th…

That would be outstanding if it could ... talk about the perfect material for shielding supercritical spacecraft components. Radiation resistance, projectile resistance, lighter than normal metal, temperature resistant... What's not to like?

You still need to make it fit, and this shielding may require more volume and more mass than a Whipple shield.

Re: Metal foam obliterates bullets

#48

Post by Jommi »

refurb wrote: post #20
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 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.

The Vampir uses a tandem charge -- Two successive charges. The point of this is to counter reactive armor, which is designed to counter explosively formed projectiles.

The "cage" slats can be effective against both.

Re: Metal foam obliterates bullets

#49

Post by spatulan »

refurb wrote: post #20
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 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.

Re: Metal foam obliterates bullets

#50

Post by spatulan »

SEJeff wrote: post #19
blisterpeanuts wrote: post #14

Earlier quoted context omitted.

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

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.
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