The economics of carriers seem way out of whack.

Please skip past the images below if you are already aware of the fighter balance discussion to see my suggestion/code.

I was just checking out the differences between the various Fighter types, having unlocked them fairly late in the game, and noticed that the higher tech 'guardian' and 'interceptor' fighter types are vastly outclassed by the standard AssaultFighter:

(note, this is a save from 1.01, so carrier modules still carried 3 fighters rather than 2 that 1.02 gives, that doesn't affect the rest of this post much though) 

As you can see, the standard Assault Fighter is.. well, it's a bit better. Mostly it's better because it is on a Small hull, compared to a Tiny hull. 

In the ShipClassDefs code it looks like the assault fighter should be Tiny:

The Terran_Knight_01T is a tiny hull, after all. 

But it refers to the BlueprintDef AssaultFighterBlueprint, which tells the game to use a small hull:

And indeed, as you can see in combat, the TerranKnight tiny hull is stretched out to be a Small:

Small TerranKnights above, vs the Tiny TerranGuardians below. This works the same for all races, not just Terran.

Of course, the modules which carry these ships have different costs:

In my current game, an AssaultFighter module costs 49 capacity, 68 manufacturing cost, and 0.8 maintenance.

By conparison, the high-tech GuardianFighter module costs 31.5 mass, 48 manufacturing, and 0.6 maintenance. 

(note: I took +15% maintenance as a handicap trait, normal values are 0.75 and 0.5)

So the GuardianFighters save you about 1/3 of the capacity requirement and cost.

Still, that isn't a whole lot... this is an approximation of the the Guardian drone's value:

So, each Guardian module provides a decent bit of gunnery firepower (4-24 dependent on tech level) on two 25-35hp Tiny hulls, which would cost ~150 build capacity to produce from shipyards; it would cost 3.8/turn to maintain these two fighters as independently built ships. At max tech, these vessels would be worth 180 build capacity each.

(Note, with the lower-mass kinetics coming in 1.02, this Guardian will be able to field point defense and shields)

Here's my recreation of the SuperKnight AssaultFighter:

Vastly more firepower than the guardian or interceptor (dependent on tech, this one will always have one 'good' weapon you've researched; you might have neglected guns or beams), with room for all defenses to shield its 50-75HP hull. Building two of these would cost me more than 750 manufacturing, and require 9 credits/turn maintenance.

Not pictured, an Interceptor module creates the DroneFighter blueprint which gives 6-96 firepower on a tiny hull... not bad tbh. An Interceptor can outdamage an Assaultfighter if you have a lot of beam tech, but still only has half the hitpoints and 1 anti-beam defense component.

In any event, this is what I pay for the vessel that delivers these wonderful little killers:

Let's say I switch out some stuff to get the 2 assault carrier modules in, I'm paying ~250 manufacturing and ticking away 2 credits per turn to field 1500 manufacturing (4x375) worth of ships. Rather than pay 17 upkeep, it's 2.

So what if this ship gets blown up in the first fight it's in? Then it's paid for itself 6x over.

But what if those Assault ships manage to stop all the enemies, at the cost of their own lives? Then next turn the carrier will have generated another 1500 manufacturing capacity to replace its charges.

Not to mention, the cargo hull costs 5 fleet logistics; the 4 small fighters it fields would cost 12.

Summary:

Carrier modules destabilise the economy and research progression in a few ways

• AssaultFighters are stronger than their higher-tech counterparts - ranging from 'considerably' to 'wtfbbq' levels of stronger
• Fighters being recreated for free each turn produces a huge amount of manufacturing capacity out of thin air
• Carrier modules save lots of maintenance cost.

• Fighters are considerably more potent in battle than regular ships of equal size due to not needing to carry life support or drive modules. 

I believe the point of carriers is to A) project power beyond the range of the small craft being fielded, and bringing more ships to the fight beyond the logistical capacity of your fleet to field independent vessels.

None of these are game-breaking, but they certainly incentivise me to use fighters whenever possible over, say, using Huge hulls filled with actual weapons. 

Suggestions:

Ordered from easy/quick to fix to harder/requires-balancing-thought 

1. Carrier module maintenance should be raised to ~2.5/turn. 
2. Perhaps carrier modules should be more expensive in manufacturing cost - right now building a carrier module costs less than 1/2 the manufacturing of 1 of the fighters it fields. This should be weighed against other possible balance remedies.
3. There should be a 'bomber' fighter type, which uses missile tech.
4. Fighters should not instantly replenish after battle; either require a cooldown (say, 5 turns?) to re-build, or perhaps more interestingly: require the carrier visit a shipyard or military starbase for re-supply.
5. Assault fighters should be tiny. In addition, there should be a Small fighter, perhaps in the place of the currently defunct EscortFighter, coming in at higher tech.

While carrier modules to manufacture 'free' meatshields (hullshields?) in the form of fighters, I don't think replenishing them should cost manufacturing. A) it would be impractical to implement, and it would be annoying for players. I don't want to make fighters less fun, just a little less economically alluring. 

Code required for suggestions above: