system
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human
[Star Trek] Why doesn't any faction have spacefighter craft to accompany the larger battleships?

When in WWII airplanes became widely used in naval warfare it changed the face of how battles on sea were fought completely. Suddenly battleships were vulnerable pieces of machinery constantly having to be on the lookout for torpedoes/bombs/50cals/30mm/etc.

Why doesn't anyone use fighter spacecraft to aid their larger ships?
gpt
Because the role fighters play is irrelevant in space. Fighters provide high-altitude support to their bases, be those bases stationary or mobile. A fighter can "see" farther than a carrier by simple virtue of its altitude, which reduces the horizon line caused by the curvature of the planet itself. On a hypothetical, completely flat "world," fighters would have no specific advantage over vessels locked to ground/sea-level, other than speed and having a closer view of a target prior to attack.

Let's talk about speed a bit. Fighters are substantially faster than naval vessels, to be sure. Why? They're smaller and consequently weigh less. It's not a question of powerplant; a nuclear-powered aircraft carrier produces substantially more power than any fighter, by a large margin. It simply has to apply that power to doing a lot more; pushing a multi-thousand-ton craft through as viscous a medium as water is a lot harder than pushing a several-ton craft through a less-viscous medium like air. For their speed, though, fighters sacrifice the tremendous range that naval vessels have. A nuclear naval craft can go for long tours of duty without needing to refuel. A fighter has a range measured in, at best, several hundred miles.

Now, take all of the advantages of a fighter over a naval ship and transport the two into space. Every single advantage the fighter had *disappears*. In space, you can see *infinitely* (provided you have sufficient imaging equipment), completely obviating the line-of-sight range advantage provided by terrestrial fighters to their naval counterparts. There is no air or water resistance to overcome, meaning the only factor in your speed (or, more relevant in space, acceleration) is your mass vs. your thrust.

Sublight thrust comes from impulse engines, which are glorified plasma rockets wrapped in a mass-reduction field that allows the ship to achieve greater acceleration with **less thrust/greater mass**. There goes the mass advantage space fighters would have in acceleration. But it goes even further than that. Ship size dictates maximum size of ship power plant (usually, the much-lauded Matter/Antimatter Reactor) and fuel reserves (both slush deuterium and magnetically-confined antideuterium, typically). Again, you're going to have big ships with much greater range than small ships -- just as in a terrestrial theater -- but you're *also* going to have more places to devote that power...like *shields* and *energy weapons*. 

In *Trek* space combat, shields are a defining factor. Without them, ships quickly succumb to the devastating attacks of their enemies. Because of its smaller power plant, a fighter is going to have substantially less enduring shields than a larger ship. Again, it compensates somewhat by needing to project those shields in a smaller volume, but not sufficiently to make up the orders-of-magnitude differences in protection. Its energy weapons are similarly going to suffer; it can't mount the huge, high-output battleship phaser arrays (or disruptors or whatever else) that a larger vessel can, so its effectiveness against a larger target is already reduced. While a fighter could certainly function as a torpedo platform, it's going to have a much lower torpedo capacity than a larger ship, and because of its weaker shields, will be much less likely to *survive* to fire those torpedoes.

In summary:

* The line-of-sight altitude advantage of terrestrial fighters over naval ships is irrelevant in space.
* The limited range of terrestrial fighters becomes a major liability in space.
* The speed/acceleration advantage of terrestrial fighters over naval ships is negated by the relative size of power plants and thrusters, as well as the mass-lightening properties of impulse engines.
* The smaller powerplant output of terrestrial fighters becomes a severe limiting factor in space, since it puts constraints on shield and energy weapon output that make fighters less durable and less potent than larger ships.
* The ability to deliver guided projectile weaponry is performed more ably by larger ships than fighters due to their endurance and higher magazine capacity.