Solar System Organization of Standardization [2017-01-31]

Can you tune the 14.4 Mt U-233 bomb down to 10 Mt and see if it's worth it then?

For some reason I can't get more than around 10 Km\s out of my railguns. Can someone post that 1g @ 50 Km\s design?

I can't access my screenshots right now (I'll try to upload one when I get home), but I recall being getting around 40 km/s with something like the following setup:
Zirconium copper rails 
1 gram amorphous carbon armature
330MW (so I could mount three on a ship with a 1GW reactor)
Rail length ~13-16 meters
Rail width ~1.5 meters (This dimension might be a bit off). 

It weighs around 200 tons and gimbals really slowly, but it's so far been quite effective.

If you change the payload to a >1 gram needle-shaped radiation shield, you can probably get more speed out of it, though I try to avoid this since it makes the game lag like crazy.

Edit: Here's a screenshot of the gun with an amorphous carbon needle:

From basic game knowledge, I can tell you that the speed of the projectiles has far less impact on lag than the number of projectiles. And seeing as rate of fire can essentially be chosen freely in this game, you could probably optimize the speed of the projectile at a lower RoF, then just push it back up afterwards.



Moving on though, I have some pressing questions about quite a few things in this thread.

First, why aren't the dense materials like osmium the best for reaction wheels? From both my understanding of how they work and my experience in the game, the densest materials would always make for faster turning than lighter materials at the same rotation speed right? My memory of it is that they work through changes in angular momentum, so a heavier wheel will have more angular momentum for the same mass, and thus be more effective, but I could be wrong.

My biggest concern is with this next section though. First, I want to note that the exact meanings of shuttle and projectile materials should probably be made more clear, because that definitely confused me for a bit at first. It didn't help that the materials presented there made absolutely no sense to me: Why are Osmium and Amorphous Carbon considered good Armature materials? The most important thing for a material being used to generate an electromagnetic force is conductivity, and those two are hardly conductive at all! They would cause immense energy losses from inefficiency. Which is why I was even more confused when Osmium was recommended as a shuttle material too. At least the rest of Osmium's properties make it good as a projectile in general, with it's magnetic properties being the only real weak point, so I could stretch my imagination enough to see it maybe being used in railguns on it's own, but using it as a shuttle is completely counterintuitive; why would you ever use something dense to accelerate something that's lighter (or in other words a worse penetrator), especially if there's no benefit to using that material for acceleration? It makes no sense, and all of my preliminary testing so far completely supports me, as does my extensive experience working on them: Railguns are my area of focus and expertise after all. There are also some other problems with the railgun section, mostly just the information about warnings. The first one, for projectiles shattering, is vague and technically not *exactly* true, but in practice it tends to be pretty reliable so other than being incomplete it's not a massive problem, but part on rupturing barrels is completely wrong. First and foremost, increasing the projectile mass will ALWAYS reduce speed, even if by an insignificant amount (Unless it's compensated for somewhere else, but that's besides the point). Also, increasing projectile mass comes with it's own problems, including causing the projectile to shatter, and iirc it can actually do the opposite and cause the barrels to break even harder.

I'm sorry if I seemed overly rude or angry in that last part, it wasn't my intention to do so, though I was slightly frustrated.
There are other things here I may want to talk about eventually but this should be fine for now. Thanks for the help

Denser materials have *less* moment of intertia for the same mass, because that means a smaller wheel with its mass concentrated closer to the axis of rotation.

The reason osmium and amorphous carbon work well, I think, is because they have good ultimate strength and high melting points. Ultimate strength lets you use a smaller diameter projectile without shattering, which increases velocity and sectional density (better against armor).  High melting point keeps your armature from melting.

Also, the railgun and coil gun modules are currently somewhat unrealistic, and power is not usually much of a limiting factor.  Power usage is mostly independent of rate of fire.  The only affect it has is on the power consumption of the mechanism that loads the armatures into the rails.  So amorphous carbon lets you build the least efficient possible railgun that doesn't turn itself into slag.  That way you can crank up the rate of fire without violating conservation of energy.  (In CoaDE, the laws of physics operate on the honor system.)

I don't know what's up with shuttles.  Somehow, adding a small lithium toothpick (minimum radius radiation shield, 100 mg or so) as a payload allows a substantial increase in muzzle velocity without exceeding material limits.  Also, even though the lithium is less dense than the shuttle, it's smaller radius increases sectional density.  This is of course horribly unrealistic, because if you had to increase the bore radius to prevent the osmium shuttle from shattering, the thin lithium rod is going to crumple up like an accordion.

Scientific realism is kind of an explicit goal of this game, so if you know anything about modeling railguns, qswitched would probably appreciate it if you made a post in the suggestions subforum about how to make them obey the laws of physics.

Edit: I think I figured out another reason why amorphous carbon works well.  The low density means that the projectile is long, so the resistance is low.  Beryllium would work well too, if it's ultimate strength were greater.

Oh, so they wouldn't scale as well with mass because the smaller radius leads to a lower moment than less dense materials when at equal masses, but it does scale well with area because it will have a greater moment at the same size as other materials, correct?

Eh, it still just doesn't make sense for railguns. At least for coilguns it requires you to use magnetic projectiles so you know it's based closer to reality, but even just the simplest equations for calculating the output of a railgun show that the output scales inversely with resistance, so these materials should just almost never be outperform real conductors, and at the very least they should be FAR less efficient. But ultimately you're right on the power usage thing, and I think that comes down to this game's systems, in particular how rate of fire works, but I've already written a whole other thread about that so there's no need to get too deep into that here. On one last note, another problem with payloads is that it allows you to choose the mass of the shuttle regardless of the area of the projectile, so it can cause weird volumes, often ones that should be far too tiny to work.