I agree with a lot of the comments here. I rarely, if ever, use Frigates or Destroyers because they’re just not effective at all.
I think their original design intent was to be point guards (with anti-missile defenses) and/or screen against fighters. They fail at the point guard role because they’re so squishy that a few shots, even at a relatively low target priority, will knock them out and leave the thing they’re supposed to be “guarding” open to missile attacks. They also fail at the anti-fighter role because all of their weapons have such low DPS values that even a squad or two of fighters can crank out damage faster than the Frigates/Destroyers can neutralize them.
After doing some historical reading, I think I see where these roles came from, in terms of wet-navy ships in the last century. Frigates and Destroyers (there’s a bit of crossover in those labels at times) were supposed to be anti-submarine (and later, anti-aircraft and anti-missile) defenses, floating around on the outer edges of a fleet or convoy. They were generally faster than most other ships, and usually carried small- to medium-strength weapons. Some examples carried a few bigger weapons - Germany liked building heavily-armed destroyers with guns comparable to some cruisers (albeit usually just one gun of that type, compared to cruisers mounting multiple batteries of large guns).
On the other hand, frigates in GSB 2 have woefully ineffective anti-fighter weapons, and virtually no viable choices for hurting heavier ships. As others have pointed out, the only weapons a frigate can mount that will penetrate cruiser shields are a paltry selection of missiles, all of which are flat-out horrible compared to existing missile launchers for cruisers and dreadnoughts.
Frigate anti-fighter weaponry suffers from such low DPS and short ranges that a squad of fighters with rockets or torpedos can usually wipe whole clusters of frigates out in seconds, with the frigates shooting down only a few fighters in return. It’s truly sad when a ship is handicapped out of the gate at the ONLY ROLE IT’S SUPPOSED TO EXIST FOR.
Destroyers are an even worse selection. They have literally HALF the available weapons modules of a frigate, and substantial speed penalties. On top of that speed penalty, they don’t have access to the top-tier engine module that frigates can mount, making them even more cripplingly slow. The only thing destroyers have going for them is their array of anti-missile defenses, but those are only moderately effective to begin with, and if your opponent has built a missile-free fleet, your destroyers and up being a complete waste of money. Even against a missile fleet, a few missile-heavy cruisers can overwhelm even a group of anti-missile destroyers and take them out one at a time. Once again, the ship is failing at the role that it seems to be designed for.
One of my most memorable experiences in GSB 1 was playing the campaign, and getting my rear end handed to me by a fleet of fast Nomad frigates with Ion Cannons. Now, Ion cannons were one of the highest DPS weapons in GSB 1, and could penetrate heavy cruiser shields. Normally, that still wasn’t an issue, because those were offset but a short range, and a pretty low Armor Penetration.
This fleet, however, was fast enough to close range (and evade my weapons) quickly, and the way the orders were structured made the ships keep dancing around and tearing my cruisers apart. It was a beautiful combination of playing to the strengths of the race (speed boosts on most Nomad ships), the strengths of the ship class (Ion Cannons were a frigate-only weapon), and using specific orders to make the ship design even more effective (Keep Moving, and having a short firing range, meant that most of my cruiser weapons couldn’t hit back effectively).
Those frigates completely obliterated a cruiser fleet 6 times its cost - one, I might add, that had experienced almost no major problems in any previous battles. I retook the planet a few turns later, but I had to design a new fleet, with at least one new cruiser design, specifically to counter that fleet and that fleet alone.
Doing something like that in GSB 2 isn’t even possible. Frigates, even frigates with missiles, can pound on a cruiser all day long and barely make a dent in it, while the cruiser just picks them apart at its leisure. Forget closing to short range - Pulse Cannons, especially of the Sledgehammer variety, make that a losing proposition for any ship (even another cruiser). That, to me, is the core problem with frigates and destroyers. They’ve been shoehorned into having only one specific role in a fleet, lack the flexibility to support innovative designs or clever use of orders, and even when you use them for the specific role they’re supposed to fill, they still suck at it.
Having some longer-range anti-fighter weaponry would help - something that can swat fighters down before the fighters get in range of torpedo barrages, for instance. Why not have a fighter-killer missile that has long range (800+), high tracking speed, high turn speed, and low shield and armor penetration? That would make them better at their intended role.
Or, while you’re at it, why not add a heavy shield-penetrating weapon for destroyers? Tribe frigates in GSB 1 could mount autocannons, which could penetrate anything but Reflective shields, did a moderate amount of damage (for a frigate weapon), and had a good tracking speed. Since all the beam lasers have low shield penetration and high armor penetration, why not bring back projectile weapons? Having a railgun-type weapon that’s specific to destroyers, has long range, and high shield penetration (but slow rate of fire and mediocre tracking speed) would give them a viable option against capital ships. If it takes gobs of power or crew, you can limit how many are on a single ship (one if you want a destroyer that can still maneuver, two or three if you’re ok with having a gun platform).
I’d also like to see destroyers have somewhat better engines. Historically (from what I’ve read, at least), wet-navy destroyers were usually more maneuverable than frigates. They weren’t always faster in a straight line, but typically mounted two screws (propellers), which let them make sharper turns and respond to threats better. Frigates might mount a single screw with larger engines, but typically had problems with turning. Why not add a new engine module for destroyers that has decent thrust but high maneuverability? Maybe a 50 thrust, 100 maneuverability engine? That gives them better turning ability, which means that modules with narrow firing arcs can be brought to bear more effectively.
I’d like to play around with more designs, but there just don’t seem to be any viable ones they way things are right now. This needs to be fixed. Right now, anything a frigate or destroyer can do, a cruiser can do 10x better - and with better chance of surviving the battle, too.