So, I sometimes get the idea that fighter craft really aren't important in 40K, especially in space battle; while I can see some use flying over a land-based army, or structures, pelting them with hits, a miles-long voidship doesn't seem like it would particularly care. The main book left them out, partly for space, I suppose, and partly because they are not always seen as critical by the military minds of the Imperium who, like another Emperor, seem to favor bigger ships over little ping-fighters. Some IN ships use them, and Rogue Traders are in a good position to get them, and be able to afford the upkeep, but what's a good use for them? Other than flying out to absorb torpedoes with their face, another expensive prospect, why carry them on your ship? Everything BFK mentions is vague mechanics from the point of view of the bridge, where someone aboard the voidship is making a roll, and the fate of the attack craft is moot, beyond the cost to replace them, with Follow My Lead! trying to do what I want, but still...

I ask this because in my story, one of my main characters is Arin Trenn, an ace pilot and Flight Marshall (a career the seemingly negative view of fighters makes me question the existence of) aboard the Passage of Judgment, a ship I haven't determined the class of, yet, but does carry fighter/bomber craft. He has the unique position of not being in an active RPG, so he's not competing with other Player Characters for the spotlight, and I want a bit more of what he does to be important in the story. Arin is away from the Passage for a few months, on personal business, and I want there to be a reason for the ship's Captain to want him to get back, rather than stay on the Rogue Trader's station, dealing with his personal business. What sort of "spectacular" stuff, that could happen in the RP, could he do, as an ace fighter pilot, in order to be missed, or are they really just relegated to crap status? Of the three, Nova Cannons, Torpedoes, and Attack Craft, the last seems to be the one hardest to justify the use of, as so much might blow one to bits; not the best place for a non-mook to be sitting.

Any in-game examples would also be cool. Thanks.

I find that my players who do the 'Ace Pilot' style of character usually fly lots of different craft, not the least of which are the humble fighters. In my experience small fighters are not unlike they were in BFG - useful as defensive screens or a last ditch response to enemy torpedoes/bombers/assault craft/etc, but not something you would actively send far afield. As you said, they will simply ping off of all but the lightest of vessels. So in my past games (my current game has no one who even remotely fits the pilot mold) I have tried to stage dramatic enemy attack runs which were not unlike large scale battles in that sure the various goobers and mooks employed by the players could maybe handle things on their own but what they really need is a daring and capable Explorer leading them dramatically into the fray to tip the balance.

So I guess my suggestion is to increase the amount of ordnance that your villains use which is more than turrets may be able to reliably handle and could be countered by fighter craft swarms. This way the continued survival of the ship is reliant on the skilled fighter pilot, ala Space Battleship Yamato, Macross, Battlestar Galactica, and so on.

It also depends on where the IN ship is posted. If it's post is a world, space station, important area of commerce, then that ace pilot would be useful on hunting down smugglers, small pirate vessels doing hit and run attacks, escort duties, scout missions, high profile secret missions (take so and so, item a, etc to x location) etc etc.

Or if the area was an important area, like a up and coming Forge World, Agri World, Hive World, area rich in rare resources, etc, and there was a high presence of attacks, ace pilots would be useful.

Example: In Quadrant ZD138YL is a gas giant and volcano world rich in resources. Orks attacked it recently, but were driven off. Even though the 4 ork ships were destroyed, some of their shuttles, savior pods, and fighter bombers escape the hulked ships and have found a home in the asteroid field. What remains of them in the adjacent asteroid fields are remnants that use hit and run attacks. While not numerous, they are determined and stubborn enough for the IN to be forced to leave a ship to guard the area. The orks have modified there shuttles for long void operations.

Note: The attack craft listed in BFK can be modified to have less Maneuverability and numbers, but have increased range. This represents advanced long range craft, instead the more versatile and common void vessels.

True Fighters in the game would best be used in a "flashpoint" type scenario where the player plays out a dogfight (Approx 2-3 rds worth) or strike mission on a ground target. Remember, An entire dogfight can easily fit into a single RT space combat turn! (Which is 30 min.) Fighters, like their modern equivalent are not generally intended to take down voidships. That is the specific job of bombers! (Which any Voidship should DEFINITELY care about!) Fighters are designed to engage other small craft in deep space! While they can operate in the atmosphere the Lightning and Thunderbolt fighters are actually more maneuverable (At least in the fluff! There are no Stats yet) and thus would have an advantage there. Additionally the Tbolt and lightning are quite a bit cheaper so that's also a factor. Fighters could also do a passable job of precision ground attack since their Lascannons are certainly NOT lightweight in a standard air to ground engagement!

On Bombers:

If the ship has 2 Launch Bays at Str 2 each, and this is an actual carrier that wants to deal damage during voidship fights... I would focus 9 of the 12 slots for bombers and the rest for fighters.

9 Bomber Squads attacking at the same time is the equivalent to a Str11, Crit 4, +40 to hit (+craft rating), 1d10+4 damage macrobattery - that ignores voidshields.

They are hard to use, yes you will take time to launch all the bombers and prepare them before doing the massive attack run. But once they are prepared they can also hit quite far away.

And if you got a nice command score, you will one-hit-kill almost anything at a decent range.

The upkeep however is an issue, so I would recommend aligning with the GM the uses for a Manufactorum together with a Small Craft Repair bay which in my games could be focused on re-building fighters that usually would be too damaged to be repaired.

On Fighters:

Not used so many times as carriers are quite rare I understand but can also help a lot with torps.

On both:

What if you are orbiting Vaporius and want to take some cities for yourself? Wouldn't it be much easier to make precision strikes with attack craft instead of using Orbital Bombardment that would reduce everything to ruble?

Once melta bomb exploding exactly over the chamber where a Priest-King usually resides could break the city's morale in one (quick) shot.

In addition to my previous post, think of how interesting classic endeavors like Into The Maw or Lure of the Expanse would be with the addition of attack craft.

You could just tell your fighters to scramble and intercept Lady Ash's arvus when she leaves the combat in Magoros.

Or get your guncutter/aquila-lander an escort in case you fear Eldar attack craft nearby.

There was this time once in Naduesh when I wanted to keep the PCs away from a specific area and I added some Rak Gol fighter-bomber-dropship craft there, they then proceeded with a plan to drag them out of their cover using a Guncutter and ambushing them with Fury Interceptors suddenly raining down from orbit.

With no practical experience whatsoever, I was thinking of using 1 Fighter / 1 Bomber squadron. Unless there's been an errata, and there seems to be a lot of those, the first bomber squadron can hit up to 3 times. I don't care so much about the critical hits when I'll be dealing 3 x 1d10+4 twice.

Is my attempt at mathhammer correct?

Also, does it make more sense to use the Archeotech Bridge instead of the Flight deck?

It's an Ordinary +10 Command test to ready all your squadrons and you just need one hit. With the Bridge of Antiquity you get +10 to Command, so it's even easier to pass, and it'll help with the bombing run too and other things you need Command tests for.

Versus the Flight Command Bridge's +5 to Command (for attack craft) and auto-passing ready squadron checks.

For carriers, I'm really fond of the Flight Bridge, because you can prepare the next wave of small craft as a crew-action (auto-succes) and thus don't have to waste a PC-action on this.

I don't use mathhammer, I just use the core mechanics currently.

And since I want to get all of the shots through the same region of the enemy's armor so I only count it once, I'd put together all squads into a single, massive, hammer blow.

they have several uses. counter ordinance, ground support, escort duty, "bug hunt", scouting, ect.

or you could go with something like the young RT scion duke starwalker in his fury fighter flying along the chaos planetkiller commanded by a death crater chaos space marine, having to send a missile into a warp drive vent the size of a shoe box.

or has that been done before?

they have several uses. counter ordinance, ground support, escort duty, "bug hunt", scouting, ect.

or you could go with something like the young RT scion duke starwalker in his fury fighter flying along the chaos planetkiller commanded by a death crater chaos space marine, having to send a missile into a warp drive vent the size of a shoe box.

or has that been done before?

they have several uses. counter ordinance, ground support, escort duty, "bug hunt", scouting, ect.

or you could go with something like the young RT scion duke starwalker in his fury fighter flying along the chaos planetkiller commanded by a death crater chaos space marine, having to send a missile into a warp drive vent the size of a shoe box.

or has that been done before?

No, I don't remember that although it might be because it was a long time ago, in a benighted sector far, far away.

My only gripe with your analogy there is the scale of RT fighters, as I've whined before. "Duke Starkiller" loses some of his cred when there's half a dozen guys in the same FIGHTER with him, so "Rogue" Squadron isn't 6-12 of the Imperium's best, but 36+ dudes, striding up the hall, after shooting down several missile volleys. When average 40K ships are longer than "current" Star Destroyers (I remember pre-Lucas-retcon, when SDs were only a kilometer long, and the Supers were only 5 km; now, after enough other nerds griped about scale, due to 70's filming and model use, the "official" size of the Executor is like 19-20 km long, argh!), even fighters need to be multi-seater affairs, and that's just to shoot down missiles. That's also part of why I'm contemplating having one of the "cool things" Korvallus has found over the years being a design for attack craft with slaved servitors in some of the stations; that let's my ace pilot feel a little more like HE did something cool, rather than only being one of a big horde of guys, only to one squadron of fighters.

One of the nice things about Korvallus is he's a nice guy, for real, a rarity in the grimdark future. This lets me skip some of the regular threats a Rogue Trader might trifle with, unless they do something dumb, first, of course. Orks, however, are always in the bad, and I can imagine even they know of his famed reputation, making them like to target ships flying under the Silver Ravens banner. Since one of the Ork rules is "hey, we neva run outta rokkits!", I could make a good case that Korvallus's fighter craft fetish aboard his ships is somewhat more justified, as Orks will always have another torpedo to fire.

I imagine a true carrier by itself is overspecialized and probably fairly squishy on it's own but your first ship probably isn't going to be a carrier anyway. It's been awhile since I read any of the rules but as others have said I remember mass bomber squadrons being absolutely brutal at least in theory and when I did read it I remember immediately thinking about trying the one fighter squadron for every two bomber squadrons methodology you see Yorke talking about.

I don't remember what the rules are on the matter exactly but I have to imagine that a group of ships with a fighter screen is probably going to thwart all but the most well equipped and determined hit and run attacks during combat. That and you need the fighters in case your enemy has their own fighters or shoots torpedos at the carrier. I would think a carrier would work very well as a second ship especially if your first ship is really macrocannon focused. Get a light cruiser hull and just fill every weapon slot with launch bays, carry mostly bombers and have it hang back a bit.

Also like others have said fighters probably have a great deal of benefits outside true starship combat especially in terms of curtailing the movement of hostile NPCs. Get a really good pilot in the seat of a small craft and it's usually extremely difficult to stop them from going wherever they want, but throw a fighter squadron in front of them and suddenly that changes. That ******* NPC you spent all that time capturing who broke out of the brig and comandeered an Arvus suddenly isn't going to get very far. That and I can see serious patrol benefits, crawling through some asteroid field in a pirate infested region? Send the fighters out ahead to scout the area and peek behind the big ones before you get there.

It's also mentioned on lexicanum that in some cases there may be an astropath added to fighter crew. IMO it can easly change dynamics of all small-craft usage - especially if one can get NPC astropaths.