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(Wired)   Bulletproof snow fort for a post-apocalyptic winter wonderland   (wired.com) divider line 23
    More: Cool, snow fort, cellulose, short supply, pure water, forts, composite materials, winter, snow  
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5969 clicks; posted to Geek » on 06 Jan 2013 at 10:03 PM (1 year ago)   |  Favorite    |   share:  Share on Twitter share via Email Share on Facebook   more»



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2013-01-06 08:37:10 PM
that article made me think of this:

images3.wikia.nocookie.net
 
2013-01-06 09:17:40 PM
Pykrete? That's not *snow,* that's frozen paper.

\and obviously, the whole "Mythbusters did it years ago" thing.
 
2013-01-06 09:27:34 PM
Mmmmmm, py.
 
2013-01-06 09:29:52 PM
How does your average person go about making pykrete?  Generally, we don;t have huge supplies of pure water and unadulterated cellulose.  But if it works with sawdust and regular water... well, I think my library in Northern Alberta is going to have a HELLUVA cool program with the kids.
 
2013-01-06 09:35:18 PM

Benevolent Misanthrope: How does your average person go about making pykrete?  Generally, we don;t have huge supplies of pure water and unadulterated cellulose.  But if it works with sawdust and regular water... well, I think my library in Northern Alberta is going to have a HELLUVA cool program with the kids.


As I pointed out, Mythbusters did it before.  They used thatched newspaper paper, which worked very well (in the episode, well enough to literally make a temporarily viable boat out of it).  Hit up recyclers and the local newspapers, see what you can procure....
 
2013-01-06 10:00:36 PM

Benevolent Misanthrope: How does your average person go about making pykrete?  Generally, we don;t have huge supplies of pure water and unadulterated cellulose.  But if it works with sawdust and regular water... well, I think my library in Northern Alberta is going to have a HELLUVA cool program with the kids.


One of the links had recipes. They just used sawdust.
 
2013-01-06 10:18:29 PM
Dear lord their mobile site is horrid
 
2013-01-06 10:28:34 PM
Bulletproof is a bold claim. Strong is a much better adjective.
 
2013-01-06 10:40:37 PM

doglover: Bulletproof* is a bold claim. Strong is a much better adjective.


*For certain values of "bullet".
 
2013-01-06 10:55:08 PM

Cthulhu_is_my_homeboy: doglover: Bulletproof* is a bold claim. Strong is a much better adjective.

*For certain values of "bullet".


A .22 can go through a board.

A 50-cal can go through a whole house.
 
2013-01-06 11:42:43 PM

doglover: Cthulhu_is_my_homeboy: doglover: Bulletproof* is a bold claim. Strong is a much better adjective.

*For certain values of "bullet".

A .22 can go through a board.

A 50-cal can go through a whole house.


Either a .38 Enfield or a .455 Webley at point blank range, according to the (possibly apocryphal) account by Churchill and British service revolver types.
 
2013-01-07 12:16:02 AM

doglover: Cthulhu_is_my_homeboy: doglover: Bulletproof* is a bold claim. Strong is a much better adjective.

*For certain values of "bullet".

A .22 can go through a board.

A 50-cal can go through a whole house.


assets.diylol.com
 
2013-01-07 12:55:24 AM

doglover: Bulletproof is a bold claim. Strong is a much better adjective.


From the linked article: Both were shot with a .243 rifle at 100 meters.  A .243 bullet fired from 300 meters can push a 1 lb object for a distance of 1000 feet.

So, with a .243, it only sustains minimal damage.  However, I'm stuck on the 1lb object flies 1000 feet when shot with a .243. How is that even possible?
 
2013-01-07 12:55:56 AM

fusillade762: doglover: Cthulhu_is_my_homeboy: doglover: Bulletproof* is a bold claim. Strong is a much better adjective.

*For certain values of "bullet".

A .22 can go through a board.

A 50-cal can go through a whole house.

[assets.diylol.com image 510x395]


I'm serious. I saw a video where the navy was testing bullets against a 4 room residential house target built to code with some armored maniquins inside.

The normal rifle rounds went through the walls and some went through the armor. The .50 cal went through the front wall, the maniquin, the middle wall, the back wall, and as far as I know kept on going deep into the earthworks backstop on the range.

The final stage of the video they tested a hand grenade. Moral of the story: don't bring yourself to a hand grenade fight.

Here's some more .50 cal going through things. Link
 
2013-01-07 01:17:30 AM

timujin: So, with a .243, it only sustains minimal damage. However, I'm stuck on the 1lb object flies 1000 feet when shot with a .243. How is that even possible?


ke= 1/2m v2

Kinetic energy is a lot more about speed than mass. A large weight at rest has much less energy than a small bullet traveling very fast. The energy of the bullet probably can't launch a 1lb object 1000 feet, though. That would require a totally inelastic collision and an inclined plane to launch the 1 lb object from and at least 1000 ft of empty space to fly though.

However, it's possible that the person writing the article misread something and farked it up. 300 m/s is about 1,000 ft/s, so maybe they got that discombobulated and thought it meant the target got moved 1000 ft, which is unlikely.
 
2013-01-07 02:16:52 AM

Weaver95: that article made me think of this:

[images3.wikia.nocookie.net image 850x478]


What is that?
 
2013-01-07 02:20:00 AM

doglover: Cthulhu_is_my_homeboy: doglover: Bulletproof* is a bold claim. Strong is a much better adjective.

*For certain values of "bullet".

A .22 can go through a board.

A 50-cal can go through a whole house.


images.sodahead.com
 
2013-01-07 04:32:58 AM
Still no defense against a Chuck Norris snowball
 
2013-01-07 07:23:37 AM
Actually, plain old snow, especially wet snow, is a pretty good bullet stopper. My father builds a snowbank to shoot into every winter. Then, come spring after the snow melts, he just picks the bullets up off the ground and melts them down and molds new bullets.
 
2013-01-07 08:38:05 AM

doglover: However, it's possible that the person writing the article misread something and farked it up


Yeah. It's not so much the kinetic energy but the transfer of momentum. Let's say the bullet is 6g (reasonable for a .243 round), traveling at 1000m/s, that's a momentum of 6,000gm/s. If it strikes a 450g target and completely transfers all of its momentum, At the end of the transaction, the target has a velocity of 13m/s.

For it to travel 333m, that's approximately 25 seconds. With a 13m/s initial velocity, and Earth gravity, I don't think there's a ballistic trajectory that gets you 25 seconds of hangtime (and even if there were, all you're really doing is increasing the distance the object has to travel).

That said, pykrete is incredibly strong, and even a high-velocity .50cal round seems likely to ricochet. They almost built an aircraft carrier out of pykrete because it was very bomb-resistant.
 
2013-01-07 05:27:22 PM

t3knomanser: That said, pykrete is incredibly strong, and even a high-velocity .50cal round seems likely to ricochet.


Uh, no. Bullets in real life don't ricochet like they do in the movies. A 50 BMG hitting really thick pykrete would make a big ass crater in the pykrete and the round, assuming plain ol' FMJ, would be deformed to hell and back and stick in. OK, it might actually fall out onto the ground in front of the pykrete but it wouldhardly be what anyone would call a ricochet.

it's almost like I know what I'm talking about

i3.photobucket.com
/That ain't no Airsoft gun, sonny
 
2013-01-07 05:50:44 PM

KidneyStone: Bullets in real life don't ricochet like they do in the movies


Funny thing, I originally wrote "almost entirely spall", which would have been more accurate, but less comprehensible to folks.

The important part is that pykrete combines the hardness of ice with the resiliency of fiber. While it's never correct to call something "bulletproof", pykrete of a thickness similar to most building materials would be highly bullet resistant.

And while I cannot claim to have fired anything quite so ambitious, I have chucked my fair share of lead downrange.
 
2013-01-07 07:43:05 PM

timujin: doglover: Bulletproof is a bold claim. Strong is a much better adjective.

From the linked article: Both were shot with a .243 rifle at 100 meters.  A .243 bullet fired from 300 meters can push a 1 lb object for a distance of 1000 feet.

So, with a .243, it only sustains minimal damage.  However, I'm stuck on the 1lb object flies 1000 feet when shot with a .243. How is that even possible?


It's actually not. The bullet might have that much kinetic energy, but the impact would never, ever transfer even close to 100% of that to the target. Most of it would go into noise and heat, most of what was left would go into deforming the target/bullet, and a tiny remaining fraction would actually move the target a little ways.
 
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