Space Fleet Combat - Background

Earlier I posted in response to a post by Steven den Beste on some theoretical and practical aspects of space fleet combat, detailing some aspects of laser weapons. So I'll just continue mining this vein.

What we're doing is trying to imagine what fleet combat might look like, given what we know or might predict about the realities of physics and engineering. This is an iterative thought process, looking at what forms weapons might take, what properties we're stuck with, how they would function, and then how these weapons can best be used and countered. Once you understand how the new weapons work, you can engage in some mental war games or mathematical calculations and perceive winning strategies, and thus future war tactics appear as a result of the thought exercise.

At no point are we allowed to just toss in some totally fantastic or imaginary property that we can't crunch numbers on, because if we do that everything devolves into spouting off about Romulan cloaking devices, Martian heat rays, and hyperspace windows opening up from Zignor VII. After all, if you're not going to apply what you know about physical reality, why did you bother coming to grips with it in the first place? Rolling the imaginary combat around in our heads reveals flaws and potential improvements or innovations in ships, weapons, and tactics, and so we integrate these into our mental model and think through the problem again.

Since we're now all connected together on the web, "peer review" is easier to get, and extremely useful, because it's very, very easy to make mistakes and overlook things when were dealing in theoreticals. "You missed a step in part B," or "You're hypothetical stealth missile would vaporize itself due to heat loads," is going to be par for the course. You just have to say "Damn. Missed that," and move on. Sometimes you may spend weeks heading down a blind alley, or think you've found the ultimate solution, only to get tripped up on one little detail. And once you think you've reached a pretty stable view of combat, someone else might point out how your agile ship can actually always be hit by something you didn't think of, and the model of Future Fleet changes yet again. And what's the real point of the exercise? To get a feel about the likely or potential future, while giving an excuse not to write up yet another post on why John Kerry sucks.

Background

In reasoning about what future space battle might look like, assuming no violations of physics as currently understood, it's helpful to first go over why fleet or air battles take the forms they do. There are clear reasons why navy ships are long, fighter planes are agile, and sailing ships fired broadsides. There are also reasons why we keep innovating in ways that force changes in our tactics and weapons, since actual weapon designers go through the same thought process that we'll apply to our space fleet exercise. They cogitate on what it's technically possible to do, and then on what advantages their potential innovation might bring. Ideally these innovations change the mathematics of winning and losing, and sometimes they even change the game itself. So let me touch on some basic concepts that will come into play.

When aerial combat was envisioned prior to WW-I many people imagined it would entail two large warplanes flying side-by-side exchanging broadsides, just like the warships of the day. The prognosticators were completely wrong because they didn't carefully consider the dynamics involved. They just assumed the new craft, armed with the same basic weapons as the old, would end up fighting in forms that were similar to the old. Along came WW-I and aerial combat quickly turned out wildly different. So we learned that ships fire broadsides and planes dogfight. Unless of course you again change the weapon dynamics and get a U-boat madly dogfighting with a destroyer, circling, pivoting, and dodging, or end up with modern fighter planes sometimes taking long range missile shots before clearing the area, as if they were PT boats. Some of the key questions that determine how you'll utilize a warship are the simple dynamics of the system of weapons and warships, taken as a whole.

Some Examples

For example if you have two sides with 4 ships, each of which simultaneously fire four missiles, the outcome is drastically different depending on the kill probability of each missile. If a missile always kills its opponent, yet flight times are long, then the ideal tactic would be to sacrifice one of your own ships by having it launch four missiles just before it's hit with four enemy missiles, yet killing each of those four enemies with a single hit of its own, for a four to one exchange ratio. However, if each ship can intercept or absorb just one missile then this strategy guarantees a loss, as the four grouped enemy ships defeat the single missile fired at each of them while combining massed return fire for a victory. They then repeat this tactic three more times to win 4 to 0. Simple stuff, but it shows how fleet tactics can be radically altered by a simple change in the physical capabilities of the weapons and ships. How single ships behave in one-on-one encounters is likewise determined by the physics, or what you might think of as the rules to a war-game that's reflective of real weapons.

For example, if aircraft carriers protect each other better when tightly grouped together, through combined defenses, while absorbing the small amount of damage from attacks that do get through, then it's best to group them in a major fleet action. But if you slightly increase the odds that an attacking plane can succeed in sinking its target then grouping your carriers just makes for one-stop shopping. The Japanese decision to group carriers at Midway was a mistake, since the combination of dive bombers and their thin decks with aviation fuel stored right underneath made single hits catastrophic. The US had separated our carriers but the Japanese kept theirs bunched, and we came away with a four to one exchange ratio in our favor. Yet with slightly less effective US aircraft or slightly tougher Japanese ships and the Japanese decision may have been correct.

Fleet combat theory prior to WW-I was extremely sound, and fleet engagements in that war almost exactly confirmed the predictions of the earlier naval thinkers. You may recall from history the naval race caused by the HMS Dreadnought. That was caused by two interesting things. Alfred Thayer Mahan's book on sea power's importance to a nation's success, and then some sound technical thoughts on how the capabilities of the day could allow a fleet to control the seas.

Gaming fleet combat mathematically showed that if a side had an advantage in total guns and throw weight, with longer ranges than the enemy, they would almost always win at fleet combat. A battle would be completely decided before smaller secondary guns could even be used. Given advances in gunnery and armor, they correctly perceived that a fleet engagement was a game of using large guns to knock out enemy guns.

The math also showed an interesting trend, in which a very slight initial advantage translated into total obliteration of the weaker side, sort of a cascade effect. Mathematically it works this way. If in each broadside exchange each of your fleet's guns has a 10% chance of knocking out an enemy's gun, and vice versa, then the side with the most guns is knocking out enemy guns faster than it is losing them. Its initial gun advantage keeps on growing till at the end of a combat it's still got half its guns left and the enemy has none. Such an analysis is also the world's easiest spreadsheet to write, and this math was reinforced by another bit of gunnery physics to drive the battleship race. In calculating the odds of making a fatal hit on an enemy gun, the way to increase the odds of a kill is to use an every larger, heavier, longer-range, more accurate gun from a more stable firing platform, i.e. a larger ship, and the way to decrease the odds of having your own gun knocked out was to make it armored more heavily, indicating the need for a larger ship. One simple piece of math and physics, a mental exercise, was pursued to its conclusion in the Yamato and Iowa class battleships.

We could possibly have our exercise end up in a similar race, regarding beam weapons, based on a simple bit of physics. A mirror big enough to resolve an image of an enemy mirror is big enough to target it with a laser. The tightness, or focus, of a laser beam follows the same optical laws of diffraction limited performance as a telescope. If we imagine a fight with beam weapons with a finite amount of energy, the side with the tightest and most intense beam can destroy the enemy's own beam weapons. This puts an upward pressure on mirror size and light frequency, and is one of the reasons lower frequency energies, like microwaves, might not be as effective, since to focus their energy they require a much larger mirror or antenna. On the other hand, microwave antennas are infinitely easier to upsize than optically perfect optical mirrors, so this might not actually work out in favor of lasers.

We also already run laser power levels to the absolute limits of our best optically reflective materials, and if you slightly exceed these levels you destroy their reflective properties, the beam's energy is absorbed by the mirror instead of reflected, and you blow the optical surface off your own weapon. This might be analogous to flawed cannon barrels that explode when you fire them. But note that a mirror twice as large as another can in general resolve or focus its beam to half the diameter of the other, while also having a reflector with four times the area, and thus potentially four times the power. Its beam can focus in one forth the area of it's half-size cousin, with four times the energy, so if this turns out to be critical to combat effectiveness then you might have a fourth power law pushing up mirror diameters. The point is that if you can put more energy onto an enemy mirror than the enemies own laser source does, you damage its reflector and render it useless. The same math and design pressures of WW-I gun on gun battleship fleet combat would apply in this case. However, we quit using battleships because we found a way to hit them without getting hit in return, and this might figure into our own design exercise. For example, after I make a long and detailed post on laser on laser combat that indicates one giant laser cannon dominates all, somebody will comment "I hit your laser cannon with a handful of sand traveling at a velocity of 0.02c. There is no counter, its surface is pitted, it's now optically flawed, you cannot fire it without it self-destructing, and "all your base belong to us." That's just how it goes.

Anyway, things like this are why did battleships died out. However, it's still very interesting that fleet commanders in WW-II would sometimes misdeploy their fleets, such as the Japanese at Midway, and this occurred because new weapons and innovations were altering the optimal tactics and strategies prior to and during the war. In essence, the rules of the game were changing under their feet. Fleet combat theory prior to WW-I was extremely sound, and the fleets in that war almost exactly confirmed the predictions of the earlier naval thinkers. But airplanes and submarines changed the game, because they can hit without getting hit in return, at least by the giant guns that were the whole basis of battleships in the first place. As technology continued to advance the elegant mathematics and tactics of battleship theory went right out the window, as did many aspects of fleet theory.

During WW-II aircraft carriers became the center of the fleet, while battleships and cruisers where used to pound shorelines instead of being the centerpiece of fleet combat or serving as armed fleet reconnaissance, respectively. Destroyers were used to hunt subs and serve as AA platforms instead of delivering torpedo attacks on the enemy's fleet, except for one incident off Guadalcanal. "Fleet" submarines were used as lone hunter killers or in wolf packs instead of as adjuncts to the main battle fleet. Just about the only warship that got used in accordance with prior theory was the minesweeper, which was indeed still used to sweep mines. But instead of being a theoretical failure, the war was actually an outstanding success for new thinking, in which advanced mathematics were brought to bear on things like searching and screening, where our college professors produced differential equations to calculate the optimal method for combat air patrols to spot and intercept enemy planes, ships, and submarines.

Just as the history of fleet combat shows major changes and innovations, so will any exploration of future space fleets. There's not just the one correct answer, but an array of them depending on which weapons are dominant at any given time. The combat can take remarkably different shapes depending on which type of weapon happens to hold an innovative advantage against some previously dominant weapon, and just as WW-II showed the optimization of tactics for ships that were designed for very different roles, so too might thoughts on space fleet combat let you explore how you would conduct your fleet actions when you've just found out you've got the wrong kind of ships, just because some guy in a lab somewhere thought up something new.

Depending on what we can build, space fleets could end up being made up of giant, unmaneuverable behemoths or small, stealthy, and agile craft. The attacks might be with extremely high velocity projectiles, guided missiles, tightly focused laser beams, or even something as odd as millions of mirrors that focus solar energy into concentrated areas of space, frying cubic mile after cubic mile in a walking barrage. But what you might end up with is just part of a continuum of thoughts on what we can build and what we can use, but as with all such tactical and technical questions the answers can get quite interesting. So I'll first be posting some thoughts on the various basic aspects that will come into play, such as dodging, spoofing, maneuver, counterfire, and ballistics. I just hope I don't put everyone to sleep.