Nuclear and Antimatter weapons - finding blast radius etc.?

[Phantasm]

Originally Posted by Nereidalbel

Concussive force of explosions gets weaker and fragments fly further in thinner atmospheres; stronger concussive forces and lower fragmentation range in denser atmospheres. Not sure on the exact formula, but math was never my strongest point, anyway.

I think (but don't fully take my word for it) the working rule of thumb is to multiply the concussive force and divide the fragmentation range by the atmospheric pressure, but I have no idea if this is RAW or even realistic.

[Nereidalbel]

Originally Posted by tbrock1031

I think (but don't fully take my word for it) the working rule of thumb is to multiply the concussive force and divide the fragmentation range by the atmospheric pressure, but I have no idea if this is RAW or even realistic.

If you ignore the "divide by 0" problem of a vacuum and just say fragmentation is slowed only by gravity, it's probably as close as you can get.

[lexington]

Originally Posted by Nereidalbel

If you ignore the "divide by 0" problem of a vacuum and just say fragmentation is slowed only by gravity, it's probably as close as you can get.

In a vacuum fragmentation simply has unlimited range, simple. Once the effective skill drops to 3 (around 200 yards) don't bother to roll at all.

[Nereidalbel]

Originally Posted by lexington

In a vacuum fragmentation simply has unlimited range, simple. Once the effective skill drops to 3 (around 200 yards) don't bother to roll at all.

Sure, *people* are effectively safe at 200 yards, but most things that will have to worry about fragmentation will have higher SM, increasing the likelihood of being hit.

[Phantasm]

Originally Posted by Nereidalbel

If you ignore the "divide by 0" problem of a vacuum and just say fragmentation is slowed only by gravity, it's probably as close as you can get.

Even outer space isn't a true vacuum, as the Pioneer and Voyager probes - among others - have attested to. An atmospheric pressure of 0.001 or less would work for most off-the-cuff equations, I think, if you absolutely have to figure out the distance of shrapnel on the surface of Luna.

[lexington]

Originally Posted by Nereidalbel

Sure, *people* are effectively safe at 200 yards, but most things that will have to worry about fragmentation will have higher SM, increasing the likelihood of being hit.

If they're SM +1 stop rolling at 300 yards.
If they're SM +2 stop rolling at 500 yards.
If they're SM +3 stop rolling at 700 yards.
If they're SM +4 stop rolling at 1000 yards.
If they're SM +5 stop rolling at 1500 yards.
If they're SM +6 stop rolling at 2000 yards.
If they're SM +7 stop rolling at 3000 yards.
If they're SM +8 stop rolling at 5000 yards.
If they're SM +9 stop rolling at 7000 yards.

It's a simple table to work with.

[Jonas]

Is this of any use to you? http://forums.sjgames.com/showthread.php?t=8659

[vicky_molokh]

Originally Posted by Jonas

Is this of any use to you? http://forums.sjgames.com/showthread.php?t=8659

Yeah, the calculation/falloff for thermal radiation was just what I was looking for. Thanks.

[Jonas]

Welcome. :)

[acrosome]

Unless you are damned close to a nuclear detonation in space there shouldn't be much blast effect. And the only "fragments" are vaporized bomb material, so probably not enough atoms flying about to worry about. Essentially, you have the Ridiculously Bright Flashbulb Of God in play. Radiation is the issue (of various wavelengths, but mostly xrays) and it will propagate much better than in an atmosphere.

But to really complicate things, if the radiation energy (or whatever it is called) is high enough (about 1e11 W/cm^2 for a microsecond) it can vaporize enough of your ship's hull to provide a concussive effect. The space wargame AV:T covers this in detail, and here is a bit of a writeup on nukes in space on Winchell Chung's website:

/spacegunconvent.php"]http://www.projectrho.com/public_html/rocket/spacegunconvent.php[/URL]

There shouldn't be much EMP at all, either. IIRC that's an effect of nuclear detonations within certain high-altitude regions of the Earth's (or any planet's) magnetosphere.