My point was that such guns might therefore be confined to nuclear powered ships. But I’m not sure I understand yours.
The goal is to make a barrel that can withstand 100 shots, but as I understand it, there’s a lot of trade space here. Not every shot of an operational system needs 64kJ of boom to travel 200 miles, so dialing back the power to what is needed to attack a particular target has the benefit of preserving barrel life.
No, they are not destined for nuclear powered ships. The only nuclear powered ships in the Navy are carriers and submarines, but those don’t carry guns. Instead, gas turbine generators on surface combatants (primarily destroyers, but cruisers are also a possibility) will feed pulsed power energy storage systems on the ship, which will then deliver the juice to the weapon. Scroll to the bottom of the page.
I think you are overestimating a little bit, 32 MJ is only 9 kWh. That would only take about 5 hours maxing out a 15 A circuit. Though I suppose 5 hours or a week to reload would be effectively equivalent in combat.
I like this from that page;
“GA is contracted and has currently partially delivered 81 megajoules (MJ) of capacitor banks for this facility. The capacitors store energy from an AC power source and release it using solid state switching technology in pulses of up to 5.5 mega-amps in 10 milliseconds to power various rail gun launcher experiments and demonstrations.”
The US Navy used to have nuclear powered Destroyers and Cruisers and there’s nothing stopping them building them again.
Looks like the Arleigh Burke runs four 20mw gas turbines, so assuming they had one doing nothing but full time capacitor charging for the rail guns, that would be…
A mere 1.6 seconds each.
Therefore not an issue of any kind at all.
Yes, there is. They are very expensive. There was considerable debate about 5 years ago whether to build a new nuclear powered cruiser, and the decision was made to not only not build a such a ship, but also not to build a new cruiser at all. And that decision was made before the current budget troubles.
That would be one humdinger of a home defense weapon.
A good long thread similar to this one (but never as good!) on technology and design of railguns is here:
http://www.strategypage.com/militaryforums/8-16454/page1.aspx
There’s nothing magical about nuclear powered ships, other than they need to refuel less frequently. If the turbines have enough power to push a large cruiser, I think they have enough power to hurl a metal rod a hundred miles.
That does look pretty freakin awesome though. According to the article I read, the Navy wants to start replacing their 5inch guns on destroyers and cruisers by 2020.
In other recent headlines, North Korea agrees to U. S. demands regarding their nuclear program, and re-starting inspections thereof, in return for U. S. food shipments. (Sorry, can’t find the article today, that was yesterday’s news, but I know y’all saw it.)
They must have seen that railgun demo video.
I don’t even know what a railgun is, or why it’s called that. Does it really accelerate a projectile along rails or something? I saw one article that explained it, but poorly. Can someone here explain, or point to a cite with a better explanation? I’m trying to fight some personal ignorance here, but so far, ignorance is winning . . .
ETA: Oh, and one of the railgun articles I saw explained the smoke and fire by saying that the projectile goes so fast, it ignites the very atmosphere itself. With no further explanation than that. Yes, I too found that unsatisfyingly vague. What stuff in the atmosphere, exactly, is burning?
People have any thoughts on the curiously shaped projectile? It seems to be very odd, certainly not aerodynamic, I assume it has to do with the working of the device.
From the article:
Which makes sense. They don’t have a 100 mile long test range.
Don’t they have a hill?
ETA: On reading, that’s not very clear. I meant to say that they could point the thing at a hill and let it impact. But I guess they’re doing this indoors or something.
Yes, it does. Two rails. Basically, you take two long conductive rails, and plug them into voltage. One of them is positive (+) and the other is negative (-). Keep the rails far enough apart that current can’t flow from one to the other.
Now you add the projectile, which is also conductive material. It bridges the gap between the two rails, so that now electricity can flow in a loop up one rail, across the projectile, and down the other rail.
The current flowing through this loop creates a magnetic field. Any conductor with current flowing through it that is in a magnetic field will experience a force. The shape of the railgun means that the projectile experiences a force pushing it outwards.
From here, it’s just a matter of getting your numbers big enough that the projectile goes Very Fast, while keeping it from welding itself to the rails.
I think I read that some designs put the projectile on a sled that is vaporised and becomes plasma. Anyone heard of this before?
They should attach a huge 10K mega decibel Ghetto Blaster on it to make the KABOOM sound.
How are they proposing to introduce the necessary stabilising spin? Or are the projectiles to be guided in some fashion?
You don’t necessarily need a spin to get an accurate projectile. The M829 sabot round used by the M1 Abrams tank is fin stabilized, not spin stabilized, and it’s very accurate.
If you look at my previous link, there’s a graphic of the flight path of the projectile. That graphic shows the projectile in a ballistic trajectory to 500,000 feet, and then is guided down to the target.
That was my first question after watching the video too. The projectile almost looks like a squared off piston from an internal combustion engine. Seems like a very strange shape for a ballistic projectile. . .
Still, it was obviously carefully machined, so there has to be a reason for the shape. Whatever the reason though, it isn’t obvious to my eye!