First off, lets ‘s start out with the proposition that this is about Space Warfare in Space Opera and Military Science Fiction. Not everything is going to obey every law of physics as we know it now. It is assumed that methods of generating enormous amounts of power and getting rid of excess heat will be found. And that processes that generate huge amounts of waste heat will become much more efficient over time. And example could be the laser. Modern lasers generate large amounts of waste heat, one thing that makes laser pistols impractical at this time. if 99.9% of the energy could be put into the beam this would no longer be a problem. And if we don’t solve those problems in the future? Then none of this stuff will happen, but it still makes entertaining reading today.
So, what about weapons in space combat? Almost anything goes if it’s well thought out. That said, there are some fallacies perpetrated in books and movies (mostly movies). As said earlier, I grew up watching Star Trek. In the original Trek the weapons carried by the Enterprise were not only really powerful, they were also fast. As in faster than light. Starships battled at hyperlight velocities and shot with weapons that didn’t miss. If you want to use such weapons then the model still works. You need something other than a normal light beam though, because those only travel at the speed of light, which, while it’s still fast, has its limitations. Let’s look at this from a historical perspective. Watch some movies about battles between ships in World War 2. They’re moving while firing. The ships turn this way and that, vary their speed, anything so they won’t be hit. If a torpedo is coming in they point the ship at the weapon and hope it misses the reduced target. The reason for this is they are dealing with unguided weapons that take time to get from gun to target. Study some of the weapons profiles and you will find guns firing at targets on high arcs that take a half minute or more to reach the target. Said target is trying to avoid being hit, and has time to do so. Most times the shooter will try to bring rounds in to bracket the target, hoping for a hit or two.
Now let’s bring this out to space. One ship fires a particle beam traveling at point nine five light. The other ship is probably going to see it coming on its sensors and tyry to move out of the way, but do they have enough time? At really close range, no, they don’t have enough time to do anything about it. From particle beam to ship in a fraction of a second is not enough reaction time. Same with rail guns firing high kinetic energy projectiles. Even worse with light beams, because you can’t even see them until they hit. You can try random maneuvers to make them miss, but unless you can move your entire enormous ship a half kilometer of more in less than a second this really isn’t going to accomplish much more than a hit to another part of the ship than what was aimed for. Now let’s move the action out to a light minute, eighteen million kilometers. You still can’t see that light beam coming, though you can maneuver at random, making your ship harder to hit, since they are actually firing at the ship they saw a minute ago. The particle beam can be seen a little sooner, about three seconds before it hits, but again, the ship could be maneuvering randomly. The rail gun projectile might be seen a half minute or more before it hits. None of these weapons can be guided onto a target that moves after the shot, with the possible exception of the rail gun projectile if it happens to have some kind of terminal guidance and propulsion system. Firing at random location might generate a hit, but enough?
Now move the ships out to a light hour from each other and you have a problem an order of magnitude greater. The chance of a hit is just about nonexistent. Add to this the spread of the beam weapons, which go from points of ravening energy to spots kilometers in diameter. This may generate more chances for a hit, but the damage will be attenuated at best. As Larry Niven pointed out in his Known Space series, shine a spread beam on a target long enough and you will heat it up. Enough? And with the ship trying to get out of the beam? So at long ranges beam weapons are not really a viable weapon. This goes for plasma weapons, shotgun blasts of ball bearings, you name it.
These leave guided weapons, whether called missiles, torpedoes or whatever. At first these don’t seem like viable weapons either. Play Star Fleet Academy, in which some of the ships have missiles, and you can see how useless fragile slow moving guided projectiles can be. Beam weapons take them out with one shot. Give a beam weapon thirty seconds and they can take out thirty weapons. Again, Weber got this right. His missiles are large, robust weapons that use advance jamming technology to hide their true position, while using the gravity fields generated by his propulsion tech to protect themselves. They are fired in waves because not all will make it through. And he uses a bomb pumped x-ray laser (or possibly gamma ray) at the end to achieve the hit to the ships protected by the same gravitation field.
I decided to use this model, with variations, for my naval combat in Exodus. Missiles are fired at long range and build up acceleration to relativistic velocities. They can correct their targeting on the way, while juking, bobbing and basically jamming the hell out of enemy sensors, making them essentially unhittable by long range beam weapons. As they get closer, into engagement range by the weapons of the vessel they are attacking they drop decoys travelling at the same velocity, and maybe employ their own beam and projectile weapons to knock out counter missiles. Now in my novels I make the direct hit the optimal attack. If you do the math you will see why. A hundred ton missile traveling at point nine five light will generate enough kinetic energy to make a gigaton warhead seem redundant. A hit would be catastrophic. So why even include that gigaton antimatter warhead? Because if a missile misses it flies off into space, unable to turn around and reacquire. So the next best thing is a hocking big explosion as close to the ship as possible.
Once you decide on your basic weaponry comes the fun part, figuring out the tactics of naval engagement. I figure that the best attack profile with missiles was at the longest range possible, allowing the missiles to build up to the greatest possible velocity before impact. Also, the faster they are going the harder they are to hit with defensive weaponry. Missiles fired at close range, unless we’re talking extreme close range, will be fairly easy to take out, and this would be the realm of the beam weapons. Missiles fired at a closing enemy would have the advantage of the closing speed, up to the limits of relativity. Firing at a receding enemy would be more of a problem, as the missiles must get up to and past the speed of the enemy, and would be easier to target with a reduced closing speed. Also the speed of the firing warship must be taken into account. Firing missiles the same direction the ship is traveling is good, as the missiles already have the velocity of the shooting vessel in their favor. Firing missiles behind the ship is bad, as the weapons must first decelerate to change directions. But sometimes a bad choice is the only one. In my books I also go into the other advantages and disadvantages of taking different shots, including the use of the hyperspace I have formulated for interstellar travel. I won’t go into those here.
The last thing I want to touch on is stealth, used so often in military scifi and space opera. Everyone has seen the cloaking devices on Star Trek. The enemy ship disappears from sight, with no way of being found, except a slight visual distortion. I really have never understood how the Enterprise computers couldn’t look for that distortion and find the ship. Now this technology seems completely possible even in the near future, with light bending fields that I really don’t understand. And other techniques can be used to absorb active sensors like radar. But what about the heat? Big ships using big engines and big weapons produce a lot of heat. Even if ways are found to offload that heat that are much more efficient than today, that heat still radiates out and can be seen. The engines could be throttled down to almost nothing, same with the weapons. But there would still be heat, unless a way in found to offload it into some kind of heat sink. Not impossible, and you just have to find a way to make it work in your story, something I have already done, with limitations.
That all I have on this topic for now, not that it’s all I have thought of on the subject. I guess if you want to see how I handle space combat in its entirety you’re going to have to read my books. I don’t claim to be the ultimate thinker in this area. I just come up with ideas that seem to work in my Universe. To me, the most important part of all of it is consistency. If it works one way it should always work that way, unless you can introduce other elements that change the equation.