General Atomics electromagnetic rail cannon

[Old Man]

Re: General Atomics electromagnetic rail cannon

 

Yes, but the acceleration is assumed if you're going from zero to Mach 31 in one gunbarrel length. I think.

[Cancer]

Re: General Atomics electromagnetic rail cannon

 

That, and Mach 31 at the bottom of Earth's atmosphere brings drastic aerodynamic forces and air-friction heating that no passenger vehicle is likely to survive.

[Kraven Kor]

Re: General Atomics electromagnetic rail cannon

 

Jules Verne begs to differ

[Tom Carman]

Re: General Atomics electromagnetic rail cannon

 

That' date=' and Mach 31 at the bottom of Earth's atmosphere brings drastic aerodynamic forces and air-friction heating that no passenger vehicle is likely to survive.[/quote']

 

I believe that this is why any serious proponent of orbital launching railguns wants to mount them on the sides of pretty tall mountains. The acceleration required to achieve orbit in one shot is too high for passengers, but using the railgun as a fixed first stage for a ship is another matter.

[Old Man]

Re: General Atomics electromagnetic rail cannon

 

Once we build the space elevator, we can hang the railgun above the atmosphere and... wait a minute...

[gewing]

Re: General Atomics electromagnetic rail cannon

 

Yes' date=' but the acceleration is assumed if you're going from zero to Mach 31 in one gunbarrel length. I think.[/quote']

 

But the space shuttle would not have been launched through a Railgun...

yes I am being pedantic. Sorry.

Well, not really sorry this time. For that I am sorry.

 

[gewing]

Re: General Atomics electromagnetic rail cannon

 

I believe that this is why any serious proponent of orbital launching railguns wants to mount them on the sides of pretty tall mountains. The acceleration required to achieve orbit in one shot is too high for passengers' date=' but using the railgun as a fixed first stage for a ship is another matter.[/quote']

 

well, that and the fact that if the railgun is several miles long, the acceleration can be reduced dramatically.

[TSandman]

Re: General Atomics electromagnetic rail cannon

 

Just seeing what has been done decades ago by a thinkerer...

 

http://en.wikipedia.org/wiki/Gerald_Bull

[tkdguy]

Re: General Atomics electromagnetic rail cannon

 

They delivered a prototype "proof of concept" back in 2006, though it wasn't supposed to reach live test firing status until 2008, due to lack of capacitors powerful enough to drive it.

 

That's this guy:

 

Here's what it actually looks like:

 

It's a 16 ton weapon mounted on a railway car, powered by a nearby building full of capapcitors - total weapon weight, an estimated 20-30 tons. Still if it works, it will be ..... almost as powerful as ordinary, much smaller, much lighter, faster-firing guns currently available. An AT round from an Abrams generates (so I'm told) around 7 MJ, so this behemoth will be almost twice as powerful as a tank mounted weapon - if they can stop it blowing up.

 

Here's a nifty picture of a similar weapon being fired:

You may note the giant cloud of superheated gas and molten metal, which is mostly coming from what used to be the gun. You better hope you hit what you shooting at - and that you only have one target - because you only get one shot per gun.

 

But here's the kicker - that photo above is of a low power version, with a muzzle velocity of 430 meters-per-second - slightly faster than a standard infantry 120 mm mortar. Not exactly a tank-killing weapon. Hell, not even an APC-killing weapon. And at 200 times the weight, 1/50th the rate of fire and 300x the cost, it doesn't even make a good mortar.

 

Where we are right now is basic research. DoD has several scales for funding projects - proof of concept, test-bed, prototype and pre-production.

Proof of concept is for wacky stuff - killing goats by staring at them, for example. Relatively small budget, just "can we even make this work" kind of stuff.

Then there's test-bed, which is bigger-budget "We think this will work - let's try and build something that resembles a workable version"

Then there's prototype, which is much bigger budget "Let's try and make a version that could actually be used outside a lab"

Then there's pre-production, at which point you are trying to make the actual thing that could be given to the military.

 

Railguns at the moment are proof of principle, being conducted by open-bid, non-classified research groups. In short, they are looking for someone - anyone - who can come up with an idea on how to build one that that , you know, won't blow a huge hole in the side of your ship the first time it's used.

 

cheers, Mark

 

Here are a couple of videos that go along with your photos:

 

 

[Markdoc]

Re: General Atomics electromagnetic rail cannon

 

Cool! I had seen the first one before (that's where the still I posted comes from) but I hadn't seen the second one.

 

cheers, Mark

[megaplayboy]

Re: General Atomics electromagnetic rail cannon

 

well' date=' that and the fact that if the railgun is several miles long, the acceleration can be reduced dramatically.[/quote']

 

In order to be safe for even the hardiest of passengers, you'd need a railgun around 200 miles long, just to accelerate at a "mere" 10g--if accelerating to 8000m/sec. For 3000m/sec, it'd still take about 45km of rail(about 28 miles).

[Lawnmower Boy]

Re: General Atomics electromagnetic rail cannon

 

Much better then to separate the crew compartment from the rail gun. Hook spaceship plus pusher plate to a big old crane, suspend it above the railgun muzzle, and ping the thing into orbit with hypervelocity solid shot! Nothing could possiblly go wring.

[Cancer]

Re: General Atomics electromagnetic rail cannon

 

Much better then to separate the crew compartment from the rail gun. Hook spaceship plus pusher plate to a big old crane' date=' suspend it above the railgun muzzle, and ping the thing into orbit with hypervelocity solid shot! Nothing could possiblly go [b']wring[/b].

 

[boldface added for emphasis]

Except, of course, the passengers' necks.

 

Great typo, BTW, and I have to wait til tomorrow to rep you.

[SSgt Baloo]

Re: General Atomics electromagnetic rail cannon

 

Much better then to separate the crew compartment from the rail gun. Hook spaceship plus pusher plate to a big old crane' date=' suspend it above the railgun muzzle, and ping the thing into orbit with hypervelocity solid shot! Nothing could possiblly go wring.[/quote']

 

Now my ears are wringing.

 

Got 'im for ya Cancer!

[LordGhee]

Re: General Atomics electromagnetic rail cannon

 

The new catapult on the new carriers are electromagnetic.

 

I woder how far they could throw a bowling ball?

 

Lord Ghee

[tkdguy]

Re: General Atomics electromagnetic rail cannon

 

Latest news about the Navy project

[Old Man]

Re: General Atomics electromagnetic rail cannon

 

The new catapult on the new carriers are electromagnetic.

 

I wonder how far they could throw a careless crewman?

 

Fixed.

[IndianaJoe3]

Re: General Atomics electromagnetic rail cannon

 

The new catapult on the new carriers are electromagnetic.

 

I woder how far they could throw a bowling ball?

 

Probably about the same distance the steam-powered ones can.

[tkdguy]

Re: General Atomics electromagnetic rail cannon

 

Senate cancels superlaser, railgun programs

 

Looking at the comments, though, nothing has changed for the engineers yet, according to a worker in General Atomics.

[Cancer]

Re: General Atomics electromagnetic rail cannon

 

Navy railgun zeroed out in Senate committee last month

[tkdguy]

Re: General Atomics electromagnetic rail cannon

 

Boo!

[Markdoc]

Re: General Atomics electromagnetic rail cannon

 

While I feel your geek sadness, just imagine the response when one of the senators on the approval board asks if they have managed to keep the railgun from exploding every time it's used and the answer is "Yessir! Now the cannon only explodes two shots in three!"

 

It's cool technology, but there isn't any indication that they can turn it into a workable prototype any time soon. Remember the original development plan was to deploy a prototype .... last year. You may have noticed that didn't happen. They got a bunch of extra money with the promise to provide a deployable prototype in 2012. It's very, very clear that ain't gonna happen either - and it's been clear for at least a couple of years that it wasn't going to happen. In fact, they're not even close.

 

At what point do you stop pouring money into a hole?

 

cheers, Mark

[tkdguy]

Re: General Atomics electromagnetic rail cannon

 

Yes, I know it wasn't anywhere near to completion. Yes, I know the project was likely to be discontinued given the current economy; I'm surprised it lasted as long as it did. Still, it would have been cool.

 

And between this and the cancellation of Project Orion, I have to do some serious revisions on my hard sci-fi campaign.

[L. Marcus]

Re: General Atomics electromagnetic rail cannon

 

...An Alternate Future, perhaps?

[tkdguy]

Re: General Atomics electromagnetic rail cannon

 

Possibly, or just move things forward in time. My original timeline was way too optimistic to begin with, although I hit close to the mark on the estimated dates on railguns and manned expeditions to Mars. Of course, I originally came up with the idea in 2006, before the economy collapsed.