Starting on the math for a Space Opera RPG universe

[BlissAuthority]

Hello, all. First off, let me say that I found Star Destroyer.net to be a very helpful and informative resource in space-opera worldbuilding. This website and Winchell Chung's site Project Rho actually inspired me to do some math for a skiffy game universe I've been working on, Armored Wing. Would the collective wisdom of the SD.net forums mind helping me work through the math and implications?

I fully expect this to be a painful and embarrassing process for me, by the way, since this project was originally inspired by mecha shows, especially Martian Successor Nadesico (to be fair, it's put some thought into its imaginary science but it's STILL a comedy anime) and the tabletop RPG Mekton Zeta. I've thought about the logical ramifications and justifications of fighty walking tanks and space fighters in this universe, both of which I now realize are tactically dubious in the real world at best. With that kind of auspicious SCIENCE!!1! starting this project, seeing you rip through my assumptions is going to hurt.

My basic starting point for the math on weapons and armor in this universe is based on a figure from this website: the listed yield of a ST:NG photon torpedo as 64.3 megatons at best. This is very useful as a starting point, because I actually (in my foolish youth) outfitted some of the Armored Wing bombers and starships with the dreaded Antimatter Torpedo.

In this universe, "Torpedo" specifically refers to an area effect weapon - a mine or missile that deals damage through a near-miss explosion rather than a collision (Kinetic or shaped-charge seeking weapons would be 'Missiles' in universe). This means that SD.net's further observation that we need to halve the listed yield in terms of actual damage done on impact goes into effect.

I also want most starships to run mostly on fusion, only using precious antimatter when they really need to haul ass and use their relatively modest FTL drives (where interstellar travel is usually 2-4 days to the lightyear, so something like 150-200c, as an aside). To this end, I'm assuming that antimatter reactions are around 35% efficient - not cost effective outside of military operations, but still pretty damn nice. (I'm assuming that if creating antimatter is more than 50% efficient, it becomes cost-effective because hydrogen is free, and the cost of hydrogen isn't even factored in.)

So, 64.3MT(0.35 efficency)= 22.505MT explosive force, and in practice 12.25MT because half of the explosion is going the other way.

This is useful because I know how many torpedo shots I want it to take to destroy a frigate in this setting! Call a frigate any starship between 2,500 and 5,000 displacement tons (making them about the size of a modern day wet naval frigate.) For our purposes, take an Armored Wing unit called the Valiant-class, a commerce-raiding "strike carrier" with 24 fighters, a missile rack/torpedo tube, some point defense ion cannons, and about nothing else.

For in-universe reasons (specifically, "OH SHIT BOMBERS scramble all interceptors this is not a drill"), I want the Valiant, the Honorable, the Audacious and other ships of the class to be basically fucked if they're attacked by torpedo bombers or patrol torpedo boats in any numbers. I figure that four to five torps should do it - three to down its shielding (which I was thinking of making a magnetically shaped wall of cold plasma - incinerates kinetics and diffracts and reflects lasers), one to disable it, and one more if you're really mean to scuttle it.

Meaning that the shields on a frigate should probably be rated to deal with 30-36 megatons of force, and the hull about 10 or so (maybe more, since most of the damage is caused by bramstellung melting components? Or am I misinterpreting something?). And this also means that capital ships, about 6000-8000 DTons, should be be about three to five times as strong - so to blow a big old hole in the Hope of Sol, you're going to need to hit it with about 4-5 torpedoes after it's shields drop, and those preferably about the shield generators and drive coils. That implies that a battleship's armor should be rated to deal with about 40-MT resistance armor, possibly less in vulnerable areas.

This also gives me a starting point for other weapons - kinetic and shaped-charge missiles, the ubiquitious ion cannon (basically Star Wars blasters: they shoot, well, ions at a nice fraction of c), laser cannon, coilguns, plasma lances (read 'Lightsabers') and plasma bolt cannons (which, for the record, are COMPLETELY USELESS against shielded targets; shields use basically the same field-jacketing technology that plasma guns do, and make the plasma bolt's containment 'crack' and seep out harmlessly).

So, it's a start. Would you terribly mind ripping this start a new one and suggesting alternatives to tech that flat out Will Not Work?