SpudFiles

This should be within the rules... and I think some of our members such as DYI would enjoy this

http://www.foxnews.com/scitech/2010/12/ ... tromagnet/

Already linked to in the XM25 thread

dangit.........

I have built a lot of rail guns and coil guns The only good thing about it it's completely silence, but less powerful and heavy

My question here is whether the energies they're throwing around are bank energies or muzzle energies. A railgun of this size may be 50% efficient, but that's still a big difference.

Either way, assuming they can solve the barrel life issue, this could be a fairly effective naval weapon.

I have built a lot of rail guns and coil guns. The only good thing about it it's completely silence, but less powerful and heavy

I'll agree that coilguns are quiet (at least the anemic, subsonic reluctance designs that people tend to build for some reason... ), but railguns? Assuming that you're talking about the inherent firing noise, and not bringing silencers and such into the mix, how the hell would you build a silent railgun?

DYI wrote: I'll agree that coilguns are quiet (at least the anemic, subsonic reluctance designs that people tend to build for some reason... ), but railguns? Assuming that you're talking about the inherent firing noise, and not bringing silencers and such into the mix, how the hell would you build a silent railgun?

Ops my bad, i meant principally to coil guns. But rail guns aren't very noisy either. But the way do you have any good electromagnetic weapons? Would like to learn more about them

wyz2285 wrote:But rail guns aren't very noisy either.

The point of electromagnetic weapons is that you can throw projectiles really fast, far beyond what can be achieved with conventional explosive propellant, so even if the launch system was silent, the noise from the projectile ripping through the air would be significant.

jackssmirkingrevenge wrote:

wyz2285 wrote:But rail guns aren't very noisy either.

The point of electromagnetic weapons is that you can throw projectiles really fast, far beyond what can be achieved with conventional explosive propellant, so even if the launch system was silent, the noise from the projectile ripping through the air would be significant.

Railguns are noisy. Boosting in amateur railguns is often done by pressurized gas. In professional guns, it's done with high end conventional propellants, often HE. It's loud.

DYI wrote:My question here is whether the energies they're throwing around are bank energies or muzzle energies. A railgun of this size may be 50% efficient, but that's still a big difference.

That's muzzle energy.

There was the question about this last time of whether the "10 Megajoule" figure was muzzle or bank energy - it was found to be muzzle energy.
And if their over three times statement is correct - well, this'd be muzzle energy too. (The general wording implies that anyway, but the relationship between the K.E. values pretty much confirms it).

jackssmirkingrevenge wrote:

wyz2285 wrote:But rail guns aren't very noisy either.

The point of electromagnetic weapons is that you can throw projectiles really fast, far beyond what can be achieved with conventional explosive propellant, so even if the launch system was silent, the noise from the projectile ripping through the air would be significant.

Well I agree with that, they do accelerate projectiles to a very high speed, but I haven't reach super sonic yet lol

Im late here,but:

Navy railgun's have a quite long rail life. A smaller 12MJ navy railgun I saw regularly fired 10+ shots in one set of rails, they used steel liners. I don't know technical specs, but the targets were 6 1" thick steel plates spaced about half a inch in a vacuum chamber. It would pierce the first 5 and the projectile would be stopped. Projectile was a typical Aluminum U with a Lexan front end.

In regards to the sound of objectes traveling over Mach1, here is a HS clip of a window as the Navy Blue Angles passed by. The myth was can a sonic boom break windows?

http://dsc.discovery.com/videos/mythbus ... gle-4.html
I'm old enough to remeber booms before they were outlawed over the US. They can and did break windows.

That was from a F-18 at very low altitude, the pressure wave generated by its motion is far superior to what a considerably smaller projectile can do! The intensity of the "boom" report in a sonic bang in proportional to the volume of the object travelling ≥ S.O.S. . A navy projectile is much much smaller!
http://ftp.rta.nato.int/public/PubFullt ... 004-06.pdf

A navy projectile is much much smaller!

At several kilometres per second, it's also much, much faster

Speed has a very significant effect on the "sonic boom", just as volume and geometry do. In all likelihood though, the majority of the firing noise of one of these big railguns would be, just as it is with more conventional weapons, the muzzle blast. Unless they've managed to get the current waveform passing through zero right as the round leaves the muzzle (which would not, so far as I can tell, be good for efficiency), there's going to be a huge, MA range arc appearing when the slug leaves the rails. As loud as the muzzle blast from a 155mm gun using a few kilos of solid propellant? Probably not, but very loud nonetheless.

My wife works on the railgun project at Dahlgren and up until a month ago I worked at Dahlgren myself.

I can tell you they do not "boost" the projectile from a static start the projectile accelerates to mach7 at max power. As for noise, that thing ROCKS!!!

If you want to see lots of cool videos go to youtube and search Dahlgren railgun.

Sorry to bring up an old post, I just think this is a cool topic.