What do we have on the launch date of the Gilgamesh? Could it be an older design?
We do not, but they show up as early as just before Wing Commander I. Blair served for 48 hours on the original TCS Gilgamesh before being assigned to the Tiger's Claw.
Good thought. And consistent with historical uses of "destroyers". During WWII, even though many large warships other than carriers carried torpedoes, destroyers were actually used to make torpedo attacks against other capital ships. The Japanese destroyers were particularly effective in this role.
More importantly, consistent with the various novels written in the wake of Wing Commander II, which have destroyers performing torpedo runs. Although it doesn't specify, Fleet Action's climactic torpedo run sequence must have been crafted with either a Gilgamesh or an Exeter in mind.
One related thought...perhaps they are capship missile tubes? WC2 doesn't mention capship missiles, but we see Kilrathi destroyers launching them (along with bioweapon missiles) in WC3, and we know the concept of a capship missile predates WC1 (because of the skipper that appears in the WC movie). Capship missiles are bulkier than torpedoes, so it would explain the entire pod sticking out from a pretty large ship better than torpedoes would. (After all, didn't a Venture corvette carry something like 6 torpedoes? Also, a Sabre. And a Longbow and Broadsword both carried four. All of these ships did so without the need for big, external pods).
That's possible, too - it couldn't have been the *intention*, since CapShip Missiles are a retcon... but it would fit with the continuity.
I don't think Ventures ever get a stated torpedo complement - and they don't show up in Milk Run, which gives us an incredibly detailed look at the innards of one of those corvettes.
There are different sizes of torpedoes, too - we see models in Fleet Action which are ten meters long (a Sabre carries one of them). The torpedoes in the Wing Commander movie are also enormous, patterned after those used on World War II submarines (and those would be contemporary to the Gilgamesh).
(Aside from Blair's magic strike Sabre, we also see Gothri with six torpedoes... and Paktahn with eight. And that's all before Arena!)
According to the Origin FX manual, the Paradigm was "one of the Confederation's most advanced" destroyers. Owing to the vagaries of the Privateer manual, we know nothing about its tonnage or length... but its armor certainly seems to be much lower than that of the Gilgamesh.