Goblins in Space!
by veilwar
Okay, not really. But in the interest of providing quality content and getting you ready for tomorrow’s really big idea post, here’s a link to an interesting and long discussion on war in space over at perfidy.
Orion Drive
The exception to much of the mass considerations discussed above is the nuclear pulse, or Orion drive. This concept involves building a very large ship with a heavy base plate attached to the back of the ship by some very serious shock absorbers. Then, you light off a small nuke behind the ship. Repeat as necessary. This is an over-the-top propulsion scheme. With this, you could accelerate very large masses very quickly. Ships using an Orion drive would simply have to be big just to make the acceleration survivable. Since you need a big ship; adding armor, huge power plants, or anything else you want is not such a big deal. An Orion powered warship would be a huge hulking brute. It would not be subtle, and stealth would be a lost cause.
No other type of spaceship (based on current technology) could match the Orion for speed and payload. It will be in a class by itself until and unless someone invents fusion or antimatter drives. Meanwhile, the inherent limitations of the other propulsion types will limit the kinds of warships that can be built around them. (As will the existence of Orion powered warships.)
The Veil War 
An Orion drive is what was a central plot piece used in one of my favorite scifi stories of all time (after Veil war of course ! ):
Footfall by Jerry Pournell & Larry Niven
Great novel. The Archangel Michael was a great concept, and well-used in the novel.
The Orion drive has appeared in lots of sf novels, but oddly, whenever someone imagines a future war scenario in solar system space, they disappear. It’s usually about getting off Earth in a dire emergency.
So that’s on my list of things to write – either future, or an alternate 1960s cold war where they actually got built by the US and then the Soviets. Or maybe the other way around? Fun either way.
If you haven’t read it, Freeman Dyson’s son wrote a history of the Orion program that is truly fascinating: Project Orion
The Orion Drive in conjuction with ion drives would do a lot to make powered flght for intrasystem travel very fast and not the months/years long gravity well slingshot trips they are now. Of course the “Nuclear Free” space treaty pretty much puts and end to the use of nukes as propulsion systems, just using thermal decay for onboard system power.
The other aspects of interplanetary war weapons talked about at perfidy are pretty much the tech that David Weber uses in his Honor Harrington series – other than the as yet to be discovered gravitic drives and all that.
I think you’d have a problem with using ion drives and Orion on the same ship. For maximal effectiveness, an Orion needs to be big – and that mass will make the small thrust of an ion drive less useful.
Back in the fifties, the guys who dreamed up the Orion thought that they could get to Saturn by 1970 if they’d been allowed to build it. Nuclear pulse drive is sufficient for pretty much all propulsion needs. If you didn’t care about freaking out the anti-radiation crowd, you could take off from Nevada and cruise straight to the outer system and back on one tank.
A very bright person had this to say elsewhere:
Until FTL communication/movement become possible the “over the horizon” effect of the speed of light lag would probably result in most capital ships being carriers of much smaller vehicles whose sole purpose is to close within the space of that data lag.
They may not be “fighters” per se since drive efficiency and fuel loads would still create fairly large combat craft so multiple crew with multiple weapon stations will probably still remain.
Mass drivers of any kind – cannon, rail guns, giant rubber band sling shots – would have significant effect on vehicle dynamics. Advanced navigation and targeting systems would enable the crew to use the resultant force vector to move the ship into position for the next firing solution and minimize fuel burn. Along the same logic it could be similar to the Age of Sail where ships pass one another exchanging broadsides since the fuel cost to alter trajectory quickly is far too great.
I do not think there would be much of an implementation of the shotgun “shoot a lot and hope you hit something” firing solutions simply because mass is far to valuable to waste that way.