MythBusters Episode 34: “Bulletproof Water”
Air Date: July 13, 2005
Hiding underwater can stop bullets from hitting you.
partly confirmed
All supersonic bullets (up to .50-caliber) disintegrated in less than 3 feet (90 cm) of water, but slower velocity bullets, like pistol rounds, need up to 8 feet (2.4 metres) of water to slow to non-lethal speeds. Shotgun slugs require even more depth (the exact depth couldn’t be determined because their one test broke the rig). However, as most water-bound shots are fired from an angle, less actual depth is needed to create the necessary separation.
It is possible to do a chain-straight 360° loop on a swingset.
busted
Under one’s own power it is impossible to do a chain-straight 360° loop on a school yard swingset. With help of other pushers, it is possible, although highly difficult, to do a full circle without the chain being straight. A person would need a rocket strapped to himself to do it. A dummy was set up in such a manner; the rocket was able to propel it in a chain-straight 360° loop, but the setup would be too dangerous with a real person.
It is possible to do a 360° loop on a rigid-arm swingset.
confirmed
A seventh generation circus performer confirmed the myth by doing a 360° loop while Tory, Kari and Grant observed. The others were not able to do the loop, as it consumes a lot of energy.
Newer: Special 8: "JAWS Special"
Thank goodness for that!!! I had been trying that as a kid, only to get a bumpy chain. Heres one. When I was about 5, curiosity made me look under the merry-go-round as it was spinning around. Yep, there was a shallow bit, and I had my head painfully stuck underneath it with my mum pulling me out. All in the interests of science. I wonder if the myth about me having no brain can be busted???
June 26, 2007 at 9:47 AMWas there ever a comparison to arrow/crossbow penetration in water?
June 27, 2007 at 2:07 PMFiring a bullet at the water at the wrong agle and it would break up or bounce off. Ever slap the surface of a pool with your bare hand? I wonder though, if you were to fire a gun while it was completly submerged IN the water and the barrel flooded with water, if the bullet would go futher than 3-8 feet. There would be no impact of the bullet and the water to slow it down. Though the friction of the water would certainly slow it down. And what about shooting a bullet from under the water at a target out of it?
July 9, 2007 at 12:32 PMIt is possible to do a chain-straight 360° loop on a swingset.
- I was a bit disappointed when you busted this myth, because it´s not a myth.
July 10, 2007 at 1:53 PMI have actually done this several times in my childhood. And so has many of my friends back then.
The difference lies in the swing. We had rubbertires as seats, fastened with stiff ironbars to the chains holding it. The swing hung from a long log in a timberrack. The friction in therack might just be the helping hand in my case, but I think you should revisit this one.. We had no rockets helping us.
Despite small details like this one; we sincerely love your show!
About the 360.. Don`t know about the swing with chains. But here in Estonia, there are swings built to do a 360. No circus needed :) Check it out: http://www.kiiking.ee/?id=75
July 15, 2007 at 4:20 AM…should have tested ‘armor-piercing’ bullets into water (…especially .50 caliber). These bullets are primarily steel, and much less likely to shatter on impact.
Only lead bullets were used on Mythbusters.
August 8, 2007 at 2:00 PMLead is obviously a soft metal, much more likely to break up when impacting water or hard sufraces.
Ken
Firng a weapon underwater with the barrel full of water will do one of two things, split the barrel or the chamber. It would not result in improved penetration of the water, just maybe the firer. As far as i know this is the only firearm that can be safely fired underwater and the projectile is actually touching what you are shooting at in the first place. http://en.wikipedia.org/wiki/Bangstick
Many spearfisher men in teh early 60’s and 70’s in Australia carried one of these usually using either a .303 FMJ or 12 shotgun cartrige. Deadly against sharks.
August 11, 2007 at 12:48 AMThere are a couple of factors that were left out in the discussion of whether a swing can do a 360. The most important one is the LENGTH of the swing. If you look at the physics (and math) for having a chain-based swing do a 360, it needs to be taught at the top, with an centripetal force equal to gravity (mg = mv^2/r), or Energy E=1/2 mv^2 = 1/2 (mgr). The difference in potential energy from the top to bottom is mgh or 2mgr. so the total energy at the bottom to make a full loop is 5/2 mgr = 1/2 mv^2, or v = sqrt(5gr). The shorter the chain, the easier it is to make it do a 360.
I have personally made an empty toddler swing (about 5 feet long) do a 360. The method used by the MythBusters was less than optimal though – rockets apply a lot of force, but don’t transfer much MOMENTUM. What’s needed is a rapid transfer of momentum to the swing (like pulling it way up and throwing it down hard – called “impetus”.
I’ll have to give it a try with my 5-year-old next… ;-)
August 28, 2007 at 11:46 AMI think the phrase that describes the result of firing a gun underwater is “breech velocity exceeds muzzle velocity.”
September 11, 2007 at 10:36 PMOops – just read on Episode 51 that a gun can be fired underwater. Learn something new every day…
September 11, 2007 at 11:31 PMI saw a guy fire a .22 pistol completly underwater, doing something highly illegal, (shooting trout). It stunned them to the point he just picked them up.
September 25, 2007 at 8:56 PMdid u try fmj s on tha water myth? iv found that the best way to shoot sumthing under water is with a 22 using sub sonic solid nose/fmjs
October 22, 2007 at 8:37 PMI am a big time hunter i do it every week end and have killed many deer. there is no way those were solid metal jackets you were shoting i actually went out and tried it and it worked with my 243. wen i first bought them i shot a deer but the bullet just went straight through causin minamal damage. A bullet that mushrooms peels back like a orange from the tip if shot a close ranges there is to much energy causin the bullet to peel all the way down leaving strips of metal just like you had
Definatly a re-visit
October 29, 2007 at 11:44 AMJames asks:
“Was there ever a comparison to arrow/crossbow penetration in water?”
The range ought to be somewhat less than a speargun, because the spear has a comparable cross-sectional area ( drag ), but nore mass and therefore more momentum. The rate of slowdown is proportional to projectile drag divided by mass,
Speargun spears are designed differently from crossbow bolts — spears have narrower, more streamlined tips to cut through the water. Crossbow bolts typically have wider tips to do more cutting damage on impact — the problem being that if you fire a stubby, wide-tipped projectile into water, there’s too much drag on the front end, which tries to decelerate faster than the back end, and the projectile tumbles end over end, slowing down when it’s broadside to the water. Crossbow bolts have no spin stabilization to keep them going straight. Nor do speargun bolts, which don’t leave the barrel fast enough to be spin-stabilized by rifling — but since speargun bolts only travel about 2.5 spear-lengths to target, it doesn’t matter.
Early shock-hunters and whale-hunters did at one time use beefed up bow-mounted crossbows with a line attached, but these were superceded by gas-powered spearguns. The target whale or shark was always either on the surface or very close to the surface, in very close proximity to the chase boat.
You probably wouldn’t want to fire a modern hunting bow or crossbow from underwater, because the bowstring would be impeded by the water, slowing it down and throwing your aim off. That’s why elastic-powered spearguns keep the elastic band edge-on to the direction of motion, to minimize drag.
Firing a crossbow down into the water woult likely have mixed results, depending on whether the flat of the arrowhead slapped the water like a skipping stone.
The main question I’m guessing would be how crossbow-fishing or speargun fishing qualifies as a myth. Obviously you can spear a target underwater without letting go of the spear. Obviously you can shoot fish from a boat with a crossbow, as Burt Reynolds was shown doing in the movie Deliverence. The only question is effective range. You won’t get much more range by speeding up the projectile, because water is nearly incompressible — plowing into water at high speed is like hitting concrete, so a carbon-fiber crossbow bolt will simply bend and deflect. A crossbow bolt isn’t going to be much geacuer than the .50 cal. round that disintegrated on striking water. A tungsten elephant-gun round wouldn’t have traveled much farther without slowing down — the general rule is that a projectile loses most of its muzzle energy after oushing aside a total mass of water equal to its own mass, which generally happens after 10-15 projectile-lengths, which for a crossbow would be the heavy metal tip on the bolt, not the lightweight shaft which is only there to stabilize and facilitate launching and extraction.
If you were to take the heaviest crossbow-bolt tip you could find, and accelerate it to elephant-gun-round velocity ( the two rounds having roughly the same mass ), the recoil would would be equally wicked. Elephant guns are large and heavy for a reason — to help absorb the recoil.
Another fact not mentioned is that if a super-spy were to fire a Dirty Harry type magnum from underwater (a) the recoil would be much greater assuming the gun didn’t burst, and (2) the stunned super-spy would float to the surface along with stunned trout, probably bleeding from the eardrums and eyeballs. When a heavy-caliber round broke open the large and heavy Mythbusters tank, imagine what the concussive damage would have been to a person IN the tank.
The easiest way to assauge your curiosity might be to rig an ‘aquatic wind tunnel’ powered by a pressure washer, and measure the drag forces on crossbow bolts and whatnot.
Still, the question of crossbows DOES have special effects appeal — we’d get to watch Janmie stumping around on a wooden leg in Captain Bligh regalia in heavy spray. Aye matey, but it’s bad luck to have a woman on board unless she be ship’s blacksmith — and what DID early whalers use for lightweight line — or did they use steel chains?
–
December 3, 2007 at 2:15 PMJames asks:
“Was there ever a comparison to arrow/crossbow penetration in water?”
The range ought to be somewhat less than a speargun, because the spear has a comparable cross-sectional area ( drag ), but nore mass and therefore more momentum. The rate of slowdown is proportional to projectile drag duvided by mass,
Speargun spears are designed differently from crossbow bolts — spears have narrower, more streamlined tips to cut through the water. Crossbow bolts typically have wider tips to do more cutting damage on impact — the problem being that if you fire a stubby, wide-tipped projectile into water, there’s too much drag on the front end, which tries to decelerate faster than the back end, and the projectile tumbles end over end, slowing down when it’s broadside to the water. Crossbow bolts have no spin stabilization to keep them going straight ( nor do speargun spears, but they travel at most a few spear lengths ).
Early shock-hunters and whale-hunters did at one time use beefed up bow-mounted crossbows with a line attached, but these were superceded by gas-powered spearguns. The target whale or shark was always either on the surface or very close to the surface, in very close proximity to the chase boat.
You probably wouldn’t want to fire a modern hunting bow or crossbow from underwater, because the bowstring would be impeded by the water, slowing it down and throwing your aim off. That’s why elastic-powered spearguns keep the elastic band edge-on to the direction of motion, to minimize drag.
Firing a crossbow down into the water woult likely have mixed results, depending on whether the flat of the arrowhead slapped the water like a skipping stone.
The main question I’m guessing would be how crossbow-fishing or speargun fishing qualifies as a myth. Obviously you can spear a target underwater without letting go of the spear. Obviously you can shoot fish from a boat with a crossbow, as Burt Reynolds was shown doing in the movie Deliverence. The only question is effective range. You won’t get much more range by speeding up the projectile, because water is nearly incompressible — plowing into water at high speed is like hitting concrete, so a carbon-fiber crossbow bolt will simply bend and deflect. A crossbow bolt isn’t going to be much geacuer than the .50 cal. round that disintegrated on striking water. A tungsten elephant-gun round wouldn’t have traveled much farther without slowing down — the general rule is that a projectile koses most of its muzzle energy after oushing aside a total mass of water equal to its own mass, which generally happens after 10-15 projectile-lengths, whixh for a crossbow would be the heavy metal tip on the bolt, not the lightweight shaft which is only there to stabilize and facilitate launching and extraction.
If you were to take the heaviest crossbow-bolt tip you could find, and accelerate it to elephant-gun-round velocity ( the two rounds having roughly the same mass ), the recoil would would be equally wicked. Elephant guns are large and heavy for a reason — to help absorb the recoil.
Another fact not mentioned is that if a super-spy were to fire a Dirty Harry type magnum from underweater (a) the recoil would be much greater assuming the gun didn’t burst, and (2) the stunned super-spy would float to the surface along with stunned trout, probably bleeding from the eardrums and eyeballs. When a heavy-caliber round broke open the large and heavy Mythbusters tank, imagine what the concussive damage would have been to a person IN the tank.
Still, the question of crossbows DOES have special effects appeal — we’d get to watch Janmie stumping around on a wooden leg in Captain Bligh regalia in heavy spray. Aye matey, but it’s bad luck to have a woman on board unless she be ships’ blacksmith — and what DID early whalers use for lightweight line that could hold a whale ?
December 3, 2007 at 2:36 PMHi,I liked that show,but seen some things that would effect results. First of all you are right shooting straight down into water increased the bullets effectiveness.
December 15, 2007 at 3:51 AMExcept the high powered rifles,that’s because the bullets aren’t designed for impact at point blank range.So a slower rifle round would be better.Best rifle rounds would be solids made for elephants and dangerous game.Like big solid 500 grain
45,50,cal and up nitro express rounds. Like you said 9mm can go up to 8ft down so that would be over the dept of a regular pool.Also guns like the 1911 .45 can be shot effectively.But barrel must be tiltedup before firing to remove a air bubble.Use waterproof ammo that like miltart varnishes primer and aroung bullet/casing meeting point.Danger one word of caution,fire guns remotely,with a rope or any design you choose.Because the guns can explode!!!!!!!!!!!!!!! Great show thanks!!!!!!!!!!!!
i forget to add the 1911 can be shot underwateri
December 15, 2007 at 3:53 AMgood idea
January 31, 2008 at 2:02 PMFor maximum penetration of high velocity projectiles into water use cavitation projectiles.FMJ rounds go further into water than sporting projectiles.Hand guns(note that – handguns) can be fired underwater – I’ve seen it done(also from underwater to an air target).There are a couple of underwater fire arms – HK make one (electricity fired pistol)-Soviets have two,an AK47 derivative and a pistol.
April 20, 2008 at 1:28 AMDon’t believe everything on TV.
Good gun myth,but wouldn’t the shock wave from the bullet hitting the water kill the shootie.
May 2, 2008 at 9:12 PMA glock is designed to be fired underwater. Glock sells a spring cup to protect the firing pin.
June 16, 2008 at 3:55 AMHello,
We are in the Middle East at an undisclosed air base and watch your show everyday at noon. Today we watched the episode above and might add you need to try using only solid, hardened, lead bullets with no copper jacket that starts the frag process.
Try it and we will be watching. I think you will find better results.
“Takin it to THEM before THEY bring it to US AGAIN!!!!
Keep em coming guys we love it,
September 25, 2008 at 4:38 AMBen
It is possible to do a chain-straight 360° loop on a swingset!! I did it when I was little on my backyard (standard) swingset. I shortened the chain until my head was very close to the cross bar. I did a 360° once, and I thought it was so awesome I had to try it again. The second time, I got to the top and fell straight down, nearly hitting the bar. Needless to say, I never tried it again. But, the myth should definitely not be busted!
January 19, 2009 at 1:40 AMGlock 19 (and others) will shoot under water. Check out the youtube video. That is one of the reasons they are the best handguns made.
February 9, 2009 at 9:03 AMFalling from a great height over water usually is fatal, but if someone had a “surface penetrating cone” under one’s feet, could one survive?
April 18, 2009 at 4:42 PM