Making EM Guns Viable in Space Combat (3e)

[GURPS Fox]

Originally Posted by Fred Brackin

2 km/second is a speed for guns used in atmosphere where ammo terminal ballistic characteristics are important. If you go radically faster your projectiles start burning up like meteors as they fly through atmosphere and then exploding like meteors when they hit.

Early railgun research did produce higher velocities but it used experimental rigs that had to be re-built after every firing and that's where they also discovered that they had limitations on useful projectiles.

Velocities higher than 2km/second can probably be produced (by unknown future tech) for combat in vacuum where it's okay if the projectile explodes on impact making shallow craters.

From my research, unless you're talking about things like Mass Effect's 'grain of sand' projectiles, you need to hit velocities up to 15km/s before the atmosphere causes problems. Though, thanks for the 'more than 2km/s units were tried, but they were completely useless after every firing' bit.

2. is a rule in Gurps Spaceships and is part of its' efforts to make projectile guns more useful.

I would say that the "best" way to make EM guns more useful is to use the ^ rules of the setting to play around with engagement distances. For example you have a setting where ships "pop" out of FTL at specific Jump points and almost all fights occur at such places at very short ranges by space standards.

If you have a hard science setting based on our solar system the the defenders of Earth will see when the enemy fleet leaves Mars and will plan their intercept at the maximum practical distance. It won't matter what EM guns "could" do. Lasers (and maybe missiles) will have finished the combat before EM guns come into even extended ranges.

For one, it depends on the setting.

For example, one setting -the lovechild between the Sci-Fi Annos and Transhuman Space- only has HePlaR rockets and would have space EM guns with velocities of 10-15km/s, given that ships can't achieve more than 5Gs of acceleration and a general tech level of TL10 with things like TL11 computers and biotech. Most combat takes place in the orbitals of a planet or asteroid.

Another setting -which is a lovechild between Transhuman Space and Traveller- has a general space EM gun velocity of 100km/s or 200km/s being the norm. Quite a few ships use a combination of HePlaR and inertialess drives (in the case of the equivalent of the Third Imperium, their warships have both, so when they get into combat, they can rocket around without paying through the nose in energy requirements) for STL movement. However, the upper limit of this is planned to be around 12Gs.