Just a quick post, and takes a bit of assumed knowledge.
Given
The Engines Cannae Take It - Starship Weapons Overview and
STOked - How Torpedos Work plus my own testing, the following is my analysis of HYT I and HYT II. I don't have HYT III but wish I did, as I'm building as if I'm going to get it.
Firstly, the correct MkVI multipluer is 1.5918, STOked's is rounded, and was giving me slight errors. That number gives me exact screen-matching numbers. I also get 1.387 for Mk IV, but I'm less sure of that off hand, I don't have that much Mk IV gear to compare.
Also, I've only checked this carefull with a Quantum Torpedo Launcher Mk VI. The only other Torpedo Launcher I have at hand is Plasma, which I presume has a different mechanic... But the numbers held as I bumped my skill from 48.3 to 78.3.
Firstly, torpedo firing speed:
Quantum Torpedos take .5s to fire and have an 8 second cool down. Photon Torpedos take .5s to fire and have a 6 second cool down.
Under HYTI, you get two torps, .45s each, and then the same cooldown. HYTII gives you three torps, .4 seconds apart, and again the same cooldown.
This is why Quantum Torpedo DPS = damage / 8.5, HYTI is damage/8.9 and HYTII is damage/9.2. Also you'll see the cooldown marker on your torpedo button restart once in a HYTI salvo, and twice in a HYTII salvo, before the 6 or 8 second cooldown counter starts. I haven't tested with multiple launchers, but I expect that's when the 3 second launcher cooldown starts as well.
Anyway, the math for HYTI and HYTII is quite easy.
HYTI fires two torpedos at
1.1831 base damage. All the rest of the calculations hold as per the assumed knowledge, so your final damage for the salvo is
2.3662 of a normal torpedo launch, but as two hits spread across .45 of a second.
HYTII fires three torpedos at
0.9157 base damage. Again, all calculations hold as normal, so your final damage for the salvo is
2.7471 of a normal torpedo launch, but as three hits spread across .8 of a second.
A quick check shows 12% more DPS but 16% more damage for HYTI vs HYTII.
I hope that's useful for someone.