elementcollector1 - 4-9-2014 at 20:59
Is there any way to even go about this?
My guess would be to find a material that allows electrons to pass through it (in the effect of the plasma railgun) but stops larger particles. All
around this would be sorbothane lining (best material I know of for soundproofing), and inside this chamber would be housed two inert gas tanks and a
high-voltage converter. The whole thing would hopefully run off of something like a car battery. Thoughts?
I know this sounds an awful lot like a pipe dream, but hey, it's always good to ask.
Metacelsus - 5-9-2014 at 08:48
What do you mean by colored?
elementcollector1 - 5-9-2014 at 10:47
As in, the discharge would be colored...
But I've decided I can do without that (unless one of you has a good idea for it).
My main concern is making it silent.
violet sin - 5-9-2014 at 11:16
high speed projectiles hitting relatively(by comparison) still air will make noise.
hyfalcon - 5-9-2014 at 11:28
High voltage contacters closing make one hell of a racket also.
elementcollector1 - 5-9-2014 at 11:30
And I'm guessing that won't be damped at all by any kind of solid insulation?
hyfalcon - 5-9-2014 at 12:41
You be the judge.
https://www.youtube.com/watch?v=OqeMGkyei1Q
elementcollector1 - 5-9-2014 at 12:45
Those guys are testing in the millions of amps, whereas mine would be barely enough to sustain the arc.
violet sin - 5-9-2014 at 13:30
if the projectile goes faster than the speed of sound, 340.29 m/s @ sea level, it will make a racket on exiting the barrel. a standard .22 cal rifle
fires between 175 to 533 m/s (wiki .22 long rifle) depending on the brand. so it(can) breaks the sound barrier making a fair amount of noise even if
there was no sound from the powder.
I'm assuming you would want at least the performance of a .22 cal rifle if you were going to all the trouble of building it and lugging around a car
battery. also wouldn't make much sense to build a 50-70 lb BB-gun equivelant or mount something that heavy on a car/platform, if you could just pump
up a BB-gun with the same success. though the coolness factor would be much less 
so assuming you managed to solve the issue of noisy contacts, ya still get sound.
elementcollector1 - 5-9-2014 at 13:44
Nope. Just want it to make a bright, repeatable flash. No actual force needed, just the light and arc.
violet sin - 5-9-2014 at 15:32
well, ok then 
not actually after a weapon would be better. deff safer. ya
never know how a home made device would hold up to that kind of stress. in the face of catastrophic failure, inherent in many home builds on a
repeated run test, a low force would be much better.
Pyro - 5-9-2014 at 16:28
bit off-topic but cool nonetheless. The US navy is developing a magnetic rail gun that propels a projectile at supersonic speed. they intend to deploy
it on a ship within the next 1-2 years to intercept incoming missiles at low cost. (only 25 000$ per round as opposed to the millions they would
otherwise need)
elementcollector1 - 5-9-2014 at 17:34
Yeah, I heard about that. I'd like mine to *not* set the atmosphere on fire, if at all possible.
smaerd - 5-9-2014 at 20:03
@elementcollector - Coil gun design is pretty intense. Might be best to start with working out a functional design to move whatever size projectile at
the velocity you want first. Then move on to the sound damping.
@hyfalcon - 2.5 million amps, yep, I'd be behind a cinder-block wall as well.
@pyro - I think that I saw a video of that thing being tested. If I recall correctly some of the preliminary tests literally spot welded the
(titanium?) projectile they were using to the gun. Absolutely absurd.
elementcollector1 - 7-9-2014 at 06:34
@smaerd: There is effectively no projectile - just an electrical discharge.
dontasker - 7-9-2014 at 11:58
Some stills of the Navy railgun and info from BAE Systems
If you want to make a silent device with a colored flash, I would think a discharge tube would be your best bet. Something like a xenon flash tube but
with a gas that creates the color you want. Something like this. Here's a video of different gasses and pressures and the effects.
I think anything you do to create an atmospheric plasma shooting out into the air will be loud. If you're only after the look you could use a fine
spray of alcohol with different chemicals added to change the flame color. Boric acid and methanol gives a beautiful green.
-edit: BAE not BEA-
[Edited on 7-9-2014 by dontasker]
elementcollector1 - 7-9-2014 at 12:53
In the first video, it seemed rather... not silent, but the effect was interesting.
The second one was also cool, but it wasn't what I was looking for.
Problem with doped alcohol is you eventually run out...