I like where you’re going with this. The idea of an anti-fighter weapon has been passed around a lot. There seems to be a general consensus that something like a flak cannon (very low damage (and DPS), but good accuracy against fighters, whether through tracking speed or AoE) would do wonders. I think your multiple gun turret would also work: a single turret that could shoot multiple ships at once would stand a better chance against a swarm of fighters. I don’t think tracking speeds and weight would even be the issue, you basically just want to make it good against fighters and not much else. Give it a really short range (the uber-dangerous laser fighters have a max range of 300 and less than that is needed to get under shields) and make armor and shield penetration negligible and it should be useless against anything but a fighter.
I think an alternative is to revisit the hit calculation. Hit chance is (1-(ship speed / tracking speed))*(0.5 + (ship size / 256)*0.5). (I hope that’s legible; that’s a lot of brackets.) Even against the fastest turret (cruiser defense laser), an average fighter (2.4 speed, 12m long) will only (theoretically) be hit 27.3% of the time. I just did a test with a 2.38 speed Federation Leopard build against a cruiser with 7 defense lasers and the actual hit rate was more like 13%. I’m also not sure what units the fire interval are in, but the 550 interval cruiser defense lasers took about 1.4s between shots. At that rate, it took 51s to take out half of the 16 ship swarm (20 HP each). A quick calculation puts that at 90 seconds to kill them all (some of the remaining fighters were probably partially damaged). I’ve seen fighters rip a cruiser to shreds in half that time.
Maybe we should change the hit calculation so that size or ship speed doesn’t have as much of an effect. It seems silly that tracking speed should have to be several times larger than ship speed just to get near guaranteeing a hit. It also seems strange that anti-fighter weapons would still be capped at about a 52% chance of hitting, just because of the size of the ship.
Still, there are lots of options for weapons. We could make a weapon like like an EMP blast that would trigger when the fighters get close to the cruiser. This would disable them temporarily, preventing them from doing damage and leaving them mostly immobile. If the timing is balanced well (maybe only fire once every 30 seconds?), this could give the cruisers a chance to decimate the fighters while still giving the fighters a chance to do some serious damage. Perhaps, as a repercussion, the cruiser is left without shields for the same time that the fighters are down. Lowering your shields to avoid being demolished by fighters would be quite a trade off, don’t you think?
Stupidly-fast tracking weapons (like the new and improved anti-fighter missiles), shorter fire intervals, multiple shots – there are lots of things we could do to tweak the numbers within the existing formula. The hardest part is making sure it doesn’t make a weapon that’s also superior against other ships. Again, range, armor and shield penetration, and overall damage are things that could balance this.
Frankly, I’d love to see powerful weapons with little to no armor penetration. That would make armored fighters a viable option.