Someone should talk about the actual post topic. 
As a bit of preamble, when it comes to tonnages in Aurora it is worth keeping in mind that the figures are somewhat hazy and ill-defined when converting from other universes to Aurora tonnage (so-called "Walmsley tonnage"). In Aurora, the closest we have to a canonical measurement is that 1 ton = 14 m3 which is the volume of 1 ton of liquid hydrogen, a value Steve has borrowed from the Traveler canon. Thus the tonnage marks in Aurora need not match the tonnage marks in other universes, for example rainyday in his Honorverse AAR finds a conversion factor of about 7 Weber tons = 1 Walmsley ton, taking a nominal value of density for Honorverse vessels of 2 m3 per ton*.
*Which, for what it's worth, I don't entirely agree with as I have found that using closer representation of armaments can approach the canonical value of 4 m3 per ton, but I digress.
Another useful benchmark is that 1 ton of steel will take up a volume of around 1/8 m3 (of course varying somewhat depending on what kind of steel you use). In this case we would have a nominal conversion factor of 1 Walmsley ton = 112 steel tons, which is clearly an extreme value (spaceships are not solid chunks of steel) but places one possible upper bound on conversion factors - to exceed this value would require using materials of extreme densities particularly once allowing space for crew quarters, amenities, and access.
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Turning to Warhammer, I would note as a preliminary statement that based on the above discussion, the 1/10 conversion factor is probably in the right ballpark, though given the difference in design aesthetic between WH40K and most sci-fi with big ships which lean towards a sleeker, "modern" appearance, we might guess that a factor of 1/20 or even 1/25 is still in the ballpark, since at least the Imperium ships are more like giant chunks of heavy metal than, say, the starship Enterprise.
I find those calculations fascinating, because I didn't know yet about the hydrogen-ton standard. If we can assume some *7 or *7/2 factor, then indeed the x10 disparity between crew and mass in Aurora vanishes, and a division by 10 would sound very original for Warhammer ships.
Regarding considering an even stronger factor, it is true that the Warhammer ships are not really known for using intelligent lightweight material, so a higher conversion might be plausible. I have already thought about rationalizing a 1/20th before, since that would still maintain my goal of "all capitals 1mt+"(due to recreation facility feasibility) while all escorts would be in a at least somewhat more achievable 300kt range.
However, I resist any uneven conversion factor so far simply on the basis that "the numbers don't look right". Shifting a zero still has me looking at: Cobra Destroyer, 5700... . But as soon as I change these first few numbers, it feels like my simulation detaches from the original lore.
..I don't know, but I am still open to the idea; just thinking it through.
In general, when designing WH40K ships, I have found that trying to match weapons at a 1:1 rate does not give good results, especially since the change to particle beams that has made them a fixed size of 300 t (600 t for lances) at all 'calibers' (I am in the camp that prefers particle beams over lasers for the lance weapons). What I have generally found effective is to count "batteries" of weapons instead, which allows flexibility to ensure that we can swap loadouts between different classes in a modular fashion and still achieve the same nominal tonnage in each case. I will admit that in some cases this could offend certain sensibilities because the art assets (both in the source books and in the video game adaptations) tend to imply a rigid " 1 Strength = 1 weapon" equivalence*, however at some point we have to make concessions to feasibility and Warhammer has always been a setting governed by the principle that everything is canon "from a certain point of view" (to recklessly mix universes), so we are not bound to consider prior artistic representations as reality.
That is no issue for me, because as you can see in the ancient topic or the Cobra above, I already broke the 1 Strength = 1 Weapon rigidity. I have no problem just grouping many guns together and then naming the fire control the gun (e.g. "Weapon Batteries" could be one FC, or "Dorsal Lances"), which I have done routinely for ships in just about every game I run. It feels natural and legal to me.
This time however, I don't even want to use lasers for weapon batteries and lances for, well, lances anymore. As Aurora goes, missile combat is the real combat, and so, unless you out-tech your enemies by about 3 engine levels, you'd really never get to deploy your mainstay Warhammer weaponry if keeping to Aurora beam weapons, especially in the more slowly moving hulks I want to make to get the feeling right.
It was no issue in that other game due to high tech level from turteling (I wanted to get back to previous game's state that was lost to a bug window). But now I will be slow, and so all the main arms should be missiles to prevent me from only engaging with "fighters" or torpedoes, which would kill immersion.
That means that weapon batteries will fire "shells" (=missiles) once more, and the lances will probably end up dispensing high EW laser warhead "charges" or something. I think that works, but the details will iron out once I actually design.
Lasers will only be there to get the point defense rating represented, and of course for the twin-linked las-guns on "fighters".
*But not universally. Note that the Cobra-class art shows two prow torpedo launchers on the side profile view, thus symmetry implies a total of four launchers, yet the BFG table for the class states a torpedo firepower of 2 - clearly this is not a case where 1 Strength = 1 Weapon in the artistic depiction. So we have some justified grounds for flexibility, and we could find other inconsistencies very easily by looking closely over the BFG ship listings.
I noticed that too yesterday, but as you said it again, I checked in the RT lore. ...It appears past me was smarter on this, because the Cobra Destroyers apparently don't equip the Voss-pattern Torpedo Tubes, which offer only 2 launchers. Those are used for some light cruisers canonically, but the Cobra instead equips the Gryphonne-pattern, which offers 4 launchers AND a 24(+4) supply of torpedoes.
So while I don't know why they yet still only fire 2 (maybe you could derive some reasoning, because there is frequent mentioning of the Cobra being an undercrewed design), I guess I saw this back then and that is why I decided to go with 50MSP ammunition for a 24 torpedo magazine on 2 launchers instead.
On all other designs, it seems to be one on one with strength to launchers though.
Given this, I think the working solution is to determine the approximate tonnages appropriate or desired for each hull type, then work out some rough rules about how many weapons or other items of a given type should make up a "battery". If you plan to work with hangars extensively, it probably makes the most sense to design your strike wings first based on whatever principles you deem appropriate. If one "battery" of hangar bays (forgive the silly terminology) is 10 kt plus whatever is needed for supporting modules (fuel, magazine, etc.) then a "battery" of weapons of any type should reach a similar mark.
Wait, you are now literally just describing what I said I did for that old post 10 years ago.
That is what I meant with "filling out the Sodoku puzzle". If I find my strike wing is 20x500t by lore, then I can check in Battlefleet Gothic on ships that replace, say a hangar bay for a short-range lance battery, and so I know a short-range lance must also be 10kt. Now knowing that, perhaps there is another spot where I can see a short-range lance be replaced by 3 short-range weapon batteries, so one of those is 3333t then.
That is how I worked that out previously, and it mostly made a consistent circle. (I also tried that two times with Tau ships, but those actually contain logical inconsistencies that lead to inequalities, so you have to wave things there)
Since all these deductions hinge on the assumption of the size of the fighters as a smallest measurement unit, it is there that I try to move the lever to get my x10 size ships in comparison to before. As said, I previously omitted that a hangar bay actually houses 3 squadrons, not one, and I guess you could also add some fuel and ammunition reserves into the assumed size. So perhaps one hangar point is actually more like 50kt already, and given how the Fury interceptors are already described as 60-70meters, (which more closely resembles modern 500t-3kt corvettes,) I could reach the needed x10 factor by just making them 1kt fighters I guess?
I was fearing they would need to be even heavier, but now that I thought about factoring their supplies in, it seems I can actually come up with a very reasonable number for a 100kt hangar per point standard.
I would also personally lean towards semi-reasonable torpedo sizes - perhaps in the range of 8 to 12 rather than size 99 - as a concession to the game mechanics, since the torpedoes should still have some use as weapons and not be purely ornamental. This may not fit the Warhammer philosophy that everything should be huge, but it will offer more verisimilitude to actual accounts of WH40K space combat where torpedo fire is actually, well, effective sometimes.
The issue with smaller torpedo sizes however is that they'd be too small to fill the larger ships again.
I will do it properly once I start designing, but ad-hoc looking at Battlefleet Gothic data, I can deduce that:
- 1 Hangar bay = 1 short-range mono-direction lance batteries (comparing CR Dictator to CR Lunar)
- 1 short-range mono-direction lance batteries = 2 torpedo tubes with 12+2 magazine (CL Dauntless special prow lance replacement rule)
- Therefore, 1 torpedo tube + magazine = 1/2 hangar bay mass
...Which means we are looking at 50kt capacity to represent one single launcher and a mere 6 missile magazine. Again, even with a 100MSP munition, one could at most get 6.5kt.
Concerning the practical use, yes, the only reason these worked well back in the VB6 game was I think thanks to large EW advantage. I used them very successfully there, simply because the enemy could not shoot these tiny 6-missile salvos down.
Of course, I'd have to ponder how to overcome this low density weakness now, but I don't think making the torpedoes smaller and then accepting lore breaking huge salvos is the solution.
Well, kind of, since I have my 2 ideas how to do it, and the first tricks around bigger salvos as well:
1) As said, I could just have a fire control be one "torpedo tube" and list a couple of warheads below in launchers. This is not as elegant as I'd want it to be, since that would allow the enemy to partially shoot down torpedoes, which makes ..some sense, but still, ehhh. It would however also allow me to organically expand the "torpedo size", so no measurement would be off the table. A mobile solution.
Even here I would however opt for at least the largest missile size possible per warhead. Steve introduced new EW rules for missiles, which in his own words could work to make 'one big high tech missile more viable than large swarms of small missiles'. Heh, that sounds like my situation exactly!
I could put lots of decoys and the like into a 99MSP body after all, and still maintain a breaching
Krawamm.
2) Well, the "torpedo" = 2.5kt ship solution. I remain unconvinced due to the whole firing procedure then probably feeling very pretentious. I guess I would feel lighter about it, if player ships could actually legally ram.
One side note is that, if we insist that our smallest true naval vessels are in the range of even "just" 500,000 tons, there is a concern that immersion may be broken when running into NPR fleets that top out at 30,000 tons for capital ships. Even with the changes to allow some NPRs to use larger base sizes we are still fighting enemy "capital ships" no more than 1/4 of our "escort" class displacements. It may be possible to adjust this by DB modding but I have not looked at the relevant tables to know if this is possible. This may be an argument for preferring ship sizes which hew more closely to "traditional" Aurora numbers - Steve's typical marks of 9,375 tons for an escort, 18,750 tons for a light cruiser, and 37,500 tons for a cruiser are reasonable here, my personal WH40K designs tend to run a mite larger but in the same ballpark, and you can certainly tack on an extra 20-30% if you include warp/jump drives on every ship. Sometime I shall investigate the DB and see if there is some possibility to configure the game to be more Warhammer than it already is, in the meantime there is always the possibility of controlling every race yourself.
Yes, I already accepted that point however. This was already a thing in VB6 Aurora, where my 300kt battlecruisers would only find 7-14kt enemy ships.
One welcome exception was a 200kt swarm mothership that almost sank my Armageddon battlecruiser.It really doesn't matter to me, for I can just rationalize to fight against the numerous lesser alien races or offshoot human colonies who could not make it past some corvette picket technology age.
I do not plan to have a great scenery where I will fight the classical enemies of humanity of 40k, so I can afford not to care here.
Concerning the jump engines: Sadly the highest jump tonnage is only just below 1mt, which is even somewhat less than before the newest changes I think.
Since they are so cheap to research and build now, I really wanted to try a jump engine game, but I guess it was not meant for me.
Anyway, thank you for the answers. The mass conversion thing changes so much for my whole playstyle, not just in this upcoming game.
Here are some WH40k designs from a recent unpublished campaign. Its looser with the BFG background than other campaigns, but I was trying out the new jump drive rules.
I found some of those designs (or similar ones?) when I peeked in your 40k game about a year ago.
I saw however, that you deviated from the official numbers a lot and took great liberty in the equipment and cross-class size factors as well. (e.g. a light cruiser is more than 3 times the size of a frigate in Warhammer)
Your game preference was evidently more in having practical use out of the ships in an actually working simulation of the Empire itself, to which cause you'd of course address that last problem nuclearslurpee mentioned: Synchronizing your fleet sizes to what you find in your enemies.
I don't want to create the whole Empire however, and just roleplay some minuscule side-pocket of it. That means I can afford to put my simulation focus on the ships itself and wave all other resulting inaccuracies and janks that it produces. It is the difference between a 'WH40k table top' and a 'WH40k epic' approach. My ships should not be legions. My ships should be characters.
