10-21-2013, 09:27 AM | #1 |
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Join Date: Mar 2006
Location: Kyïv, Ukraine
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[Spaceships] Conventional and EM Gun ranges in atmosphere?
Greetings, all!
Spaceships guns are normally treated as having infinite range (but minuscule chance of hitting stuff) because in vacuum there's nothing to stop the shells. However, when used in atmosphere, things change. So, how do I figure the ½D and Max ranges for the various ballistic Weapon Batteries? Thanks in advance! |
10-21-2013, 09:41 AM | #2 |
Join Date: Jun 2013
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Re: [Spaceships] Conventional and EM Gun ranges in atmosphere?
While they're a bit large, you might be able to use Douglas Cole's spreadsheet (if you have it; the Google doc for it appears to be down) for the calculations. Caliber and muzzle velocity (1 mps for conventional, 2 mps for EM) are easy enough. Rounds designed for use in space might not be very aerodynamic, but it's probably best to assume they have the same general shape as typical artillery shells.
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10-21-2013, 11:09 AM | #3 | |
Join Date: Mar 2013
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Re: [Spaceships] Conventional and EM Gun ranges in atmosphere?
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10-21-2013, 11:28 AM | #4 |
Join Date: Feb 2005
Location: Berkeley, CA
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Re: [Spaceships] Conventional and EM Gun ranges in atmosphere?
As a horribly crude approximation, figure that atmospheric half damage range is about 50,000x projectile diameter (so 100m per mm of size). This assumes fairly long streamlined projectiles, and is probably overly generous, but GURPS tends to be rather generous with its 1/2d ranges.
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10-21-2013, 11:51 AM | #5 |
Join Date: Aug 2008
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Re: [Spaceships] Conventional and EM Gun ranges in atmosphere?
Using DouglasCole's formulas, I get a 2cm shell with a 1 mps muzzle velocity having the following stats:
Damage: 69d+2 pi++ Range: 3,800/26,000 yd This assumes an aspect ratio of 3:1, and DU slug. Increasing the aspect ratio to the upper end of modern 20mm shells (6:1), you get: Damage: 99d+2 pi++ Range: 9,700/48,000 yd Running with a muzzle velocity of 2mps, you get the following: 3:1 Aspect Ratio Damage: 142d+3 pi++ Range: 3,800/35,000 yd 6:1 Aspect Ratio Damage: 205d pi++ Range: 9,700/64,000 yd
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10-21-2013, 11:56 AM | #6 | |
Join Date: Jun 2013
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Re: [Spaceships] Conventional and EM Gun ranges in atmosphere?
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According to Wikipedia, the M198 Howitzer is going to be right around 16cm, and the RAP (rocket assisted projectile) configuration is probably about right for Spaceships. That has a maximum range of around 33,000 yards, which is about 1/3 what we'd get using the above... so 1000n/2000n might give us a better approximation. |
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10-22-2013, 01:51 AM | #7 | ||
GURPS FAQ Keeper
Join Date: Mar 2006
Location: Kyïv, Ukraine
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Re: [Spaceships] Conventional and EM Gun ranges in atmosphere?
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Just saying. |
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10-22-2013, 01:55 AM | #8 | |
GURPS FAQ Keeper
Join Date: Mar 2006
Location: Kyïv, Ukraine
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Re: [Spaceships] Conventional and EM Gun ranges in atmosphere?
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Edit: that's half, not twice. That is, the Pyramid autocannon has less ½D. Last edited by vicky_molokh; 10-22-2013 at 02:04 AM. |
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10-22-2013, 01:58 AM | #9 | |
Join Date: Feb 2005
Location: Berkeley, CA
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Re: [Spaceships] Conventional and EM Gun ranges in atmosphere?
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10-22-2013, 02:06 AM | #10 |
GURPS FAQ Keeper
Join Date: Mar 2006
Location: Kyïv, Ukraine
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Re: [Spaceships] Conventional and EM Gun ranges in atmosphere?
I'm not sure, that would imply that an object will drop its kinetic energy to zero at the same distance regardless of the kinetic energy it had. How would that happen?
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Tags |
ballistics, guns, spaceships, weapon batteries, weapon battery |
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