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Pearls of Weber

A collection of posts by David Weber containing background information for his stories, collected and generously made available Joe Buckley.

Heavy spinal-armed units

There's been a fair amount of back-and-forth about the possibility of really powerful spinal mount energy weapons. The term "Hellbore" is being used. Basically, people are proposing a light-speed weapon with a range measured in light-minutes. There are questions about whether or not it would be possible to target something as small as a warship at those ranges in the first place. Assuming that's possible, and that it's possible to put sufficient energy on the target to make it worthwhile, there's also the question of evasive maneuvers. Care to comment?

 

It's not going to happen. The primary restriction in the range of current-generation energy weapons is the inherent "pointing" sensitivity of such high-powered emitters, coupled with the difficulty in "seeing" the target. I've commented before on the fact that unless a ship is configured for maximum possible acceleration, and unless you have exact figures on its compensator efficiency, it's literally impossible to predict exactly where within the internal volume of its wedge it might be located at any given moment. When people in the Honorverse speak of "burn-through" range against a sidewall, they are actually talking about two separate but related problems:

(a) actually getting through the sidewall with sufficient energy (and energy density) to inflict damage, but also

(b) the ability to "see" through the sidewall well enough to accurately target the ship on the other side of it in the first place. Even when the target isn't obstructed by a sidewall, lining up on it well enough to hit it is a far from trivial task, even for Honorverse technology.

The limiting factor against a target not protected by a sidewall is the maximum effective pointing ability of a very, very "hot" emitter. However, even if it were theoretically possible to hit a target at a range of a light-minute or two, the weapon would be effectively useless against anything other than a unit which had already been crippled, since evasive maneuvers for impeller-drive ships are easily come by. If it takes 60 seconds for the energy weapon to reach its target, and if the target in question decides to alter course 30 seconds after the weapon has fired and does so at an acceleration rate of 400 gravities, it will change its predicted location by over seventeen hundred kilometers. A much smaller acceleration would produce sufficient displacement -- without materially changing the evading ship's base factor -- to make it literally impossible for the firing ship to hit it. And, yes, I know that we're talking about a light-speed weapon. So what? If the other side had the capability to target you with energy weapons at such enormous ranges (which it doesn't), you would routinely adopt an evasive movement pattern. It would be child's play for the entire fleet to load a preprogrammed set of helm orders before they ever left port. Using a random number generator, they could quite easily come up with a series of helm changes which would keep them moving along their selected base course while zigzagging back and forth across it in three dimensions. It would be nothing more than the direct descendent of the anti-torpedo zigzag maneuvers routinely used by wet navies. You didn't suddenly begin zigzagging when you detected an incoming torpedo; you did it continually, to make it impossible -- or at least very difficult -- for a submarine to get into firing position in the first place. And it's worth noting, that despite their relatively huge size, Honorverse starships are actually much more maneuverable than wet navy ships, not to mention having the ability to maneuver in three dimensions. Of course, they don't have to do that in the first place, since targeting even a non-evading starship at the sorts of ranges you seem to be talking about is effectively impossible. (Of course, all of this assumes that the "non-evading starship" has an active wedge and is at least capable of maneuvering; if you want to shoot at a drifting hulk which no longer has the capability to alter its trajectory at all, your targeting systems might be up to the task. Of course, in that case the question becomes why you're bothering to shoot at the target in the first place.)