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Guy Creates Handheld Railgun With a 3D-Printer (engadget.com)
turkeydance writes: Using a combination of 3D printing and widely available components, David Wirth built a functioning handheld railgun that houses six capacitors and delivers more than 1,800 joules of energy per shot. So far he has tested the gun using metal rods made of graphite, aluminum and copper-coated tungsten. David has shot projectiles at over 250 meters per second in tests.
AK-47: 715 m/s
.44 Magnum: 360 - 450 m/s
Black powder musket: 120 - 370 m/s
Yes - though not at the level of the one in TFA and probably, for the foreseeable future, only in the realm of large naval guns (and possibly - slightly further down the line - guns mounted on tanks or large aircraft).
With a traditional naval or tank shell, much of the damage comes from the explosive contents of the shell (which tend to be quite sophisticated in their design these days). The downside of this is that the ship or tank ends up carrying a substantial quantity of explosive material, just waiting to be set off. Magazine explosion is a particular danger for ships.
Railguns, by contrast, fire inert slugs. The damage comes from the (much) higher velocity at which the slug is fired, which translates into much higher kinetic energy transfer on impact. This means that the ammunition tends to be smaller (so you can carry more of it) and safer. The higher velocity also has significant potential benefits in terms of accuracy.
The US Navy is currently conducting real-world tests of railguns on ships and there has been a lot of progress over the last few years. The challenges include the high power requirement and the need to replace rails regularly (due to the extreme stresses associated with each firing), which can substantially harm rate of fire.
Practical handheld railguns which offer significant benefits over existing firearms are still a long way off (if, indeed, they ever happen). The one in TFA has a muzzle velocity which is at the low end of the range for a "traditional" firearm, with significantly lower convenience (and some quite worrying looking safety issues).
Unfortunately, the "Mach 8" version is ridiculously long and only works once. It needs rebuilding between shots, and is ridiculously expensive. It's easier, and more aimable, to fire an ICBM. The allegedly more practical versions can be safer on a nuclear vessel, which has a prodigious and stable and well well armored power supply, as opposed to having an armory filled with chemical propellant powered munitions that have to actually be loaded, full of chemicals, into the weapons on deck.
They've also really not perfected projectiles without electrical contact with leads on the railgun's launching rail. Those leads tend to wear out *really fast*, much faster than the rail gun builders like to admit: it's been a limiting factor since the first designs, once that keeps being "solved" with a lot of handwaving that has never worked well. Kind of like garbage collecting in Java, actually....
Umm, the primary round shot from a tank gun is APFSDS (Armor Piercing Fin Stabilized Discarding Sabot). It's a big dart. No explosive at all.
"I do not agree with what you say, but I will defend to the death your right to say it"
That's not a bad guess, but not really true, for four reasons.
First, there is no "moment of detonation", powder doesn't detonate*, it burns quickly, producing gas. It's a lot of gas in a small space, so it's under pressure and that pressure pushes the bullet out. The powder continues to burn as the bullet moves down the barrel and even -after- the bullet leaves the barrel, producing muzzle flash. In pictures you may have seen the "fire" coming out of the muzzle. That fire is burning powder, meaning it's still burning after the bullet is gone.
To look at it from another perspective, imagine a firecracker on a stick. When the cracker blows, the stick doesn't get shot "backward" toward whoever lit it. The recoil exists because (and while) the bullet and gas is being propelled down the barrel. So the duration of recoil force to the slide is the same as the duration of pushing the bullet down the barrel, equal and opposite at any given instant.
Third, slide -momentum-. The mass of the slide means that the recoil force increases the momentum of the slide, and the hand feels the force as you resist the slide's recoil - meaning the hand or other mount feels the recoil until the slide stops, after the bullet has hit the target.
Lastly, the slide -move- relative to the frame (and hand or other mounts) against a spring. Since the slide is pushing on the spring, and the spring pushing on the frame, it's actually the pressure of the -spring- that pushes on the frame. Therefore the mount experiences only as much recoil as the resitance of the spring at that portion of its travel.
* Some powders contain ingredients that -could- detonate if they were pure, but they are mixed with much slower burning components in order to slow them to a conflagration.
This is 100% fake.
http://o.aolcdn.com/hss/storag...
1: That's not handheld.
2: That's a CO2 tank.
He's built a paintball gun and put a bunch of shit on it, then added sparks at the end of it.
1800 Joules is way over a fucking 44 magnum (1300-1500). Yet if you look at the videos posted, you can see that when he fires at some particle boards nothing fucking happens. The "article" original claimed it was 3,000,000 Joules. LOL!
If you read the video descriptions on Youtube, he claims:
WXPR Test 3 - 1" long 0.25" aluminum sabot (1.1g total mass). 1.6kJ caps, 500 psi injector. 36" distance to target: angled 3/4" plywood board with 1/4" mild steel backplate. Made a 1/2" deep indent in target and bounced off. Speed was above 250m/s.
Successful proof of concept for repeatable shots on the same set of rails.
So, 1600 J, not 1800. And that tank at 500 PSI is an "injector"? LOL! It's an air gun with some capacitors for no reason!!
His latest video involves shooting a cantaloupe, because everyone laughed when he couldn't penetrate plywood. He claimed they were "steel backed" plywood boards, but he still barely put a dent in them.
Here's the cantaloupe: https://youtu.be/t0vCiafjUy8 He allegedly fires at around 1300 J according to his own LCD display. There's an odd cut at 1:51 in the video as well, so I have no idea what he's actually doing. (Watch from 1:49 to 1:52 at 0.25 speed to see the cut). You can watch the shot in slow mo too.
Here's a 44 magnum shooting a watermelon: https://youtu.be/dYtfq8KdlnE A 44 magnums runs at 1300 J to 1500 J. Do they seem at all comparable?