Posted by: Vandermeer
« on: February 21, 2024, 02:34:14 PM »For those who are interested, I have run some numbers over the last week and progressed in my attempt to project a replica conversion of official Warhammer ships into Aurora. I translated all available official data into an excel sheet to have a better overview, which I attached, but the concluding reasoning came later.
WH40k Ship Builder.xlsx
Hangar/Launch Bay logical basis
I've finally settled on the 1/10 conversion factor after rummaging through the Rogue Trader and Battlefleet Gothic statistics to see if I could make it round. Remember that the fall and feasible here relies entirely on the hangar bay sizes, since that is the one tonnage that can be expressed in clear numbers in Aurora. From there you just look up conversion ratios of Launch Bays to other armaments.
There has been some change however that came from me forgetting a crucial thing about Warhammer ships: While Launch Bays can "fire" from wherever they are on the ship, the broadsides they replace on the models can only ever show one side to the enemy.
Previously I was thinking that a set of 3 squadrons of either 20x1kt size fighters and 10x2kt size bombers would combined with some magazines and fuel make for a good 100kt per Launch Bay modeling basis.
Well, since I can now however only legally count one side of weapon broadsides for engagement, and it is reasonable to assume hangars to be somewhat more empty, I have a good deduction for why I can come back to completely normal fighter and FAC sizes with 20x500t and 10x1kt for fighters and bombers.
One launch bay under this reasoning basis would be 50kt.
Hangar to Weapon conversion factor finalization
Though I did find consistent conversion patterns to batteries or lances, and even had a scipy regression algorithm confirming the same ballpark region, it eventually dawned on me that the few outstanding contradictions (e.g. the Defiant Light Cruiser) could be resolved by a simplification that should have been obvious from the beginning:
Instead of making a set of equations like
- 3 short range monodirectional weapon batteries (WBSRM) = 1 Launch Bay (=2 on broadsides aka 100kt)
- 1 short range monodirectional lance battery (LASRM) = 1 Launch Bay (=2 on broadsides aka 100kt)
...I could just acknowledge that the launch bays take up the same space on the models as one of those sets of weaponries every time, and thus should roughly just take up as much tonnage. Also, although I found the pattern where lower range weaponry converts to higher range with the factor 2/3rd (e.g. 3 WBSRM = 2 WBMRM), that merely relates to salvo density, not tonnage. It will be considered for modelling the munition size and launcher-to-magazine ratios later, but has nothing to do with the correct mass factor deliberation. Under those two assumptions, all inconsistencies to official data are settled for broadsides.
That is different the switch from mono-directional weaponry to omni-directional one. Evidenced by the Sword and Firestorm Frigate designs, which switch 2WBSRO to 1 LASRM while maintaining all other stats the same (pt cost, mass, turrets, etcetc), there also is a 2/3rd conversion factor here, since weapon batteries convert to lances 3:1 otherwise with perfect consistency. So 2 WBSRO = 3 WBSRM = 2 Launch Bays, which is the reasoning path that now confirms the tonnages for dorsal weaponries that don't have hangars for direct comparison.
Applying all deduction above and also considering 1:2 conversion cases between LASRM and Torpedoes, as well as 6:1 Torpedoes to Nova Cannons, the final weapon tonnage rules are:
- 100kt per broadside module on cruisers (whether weapon batteries or lances)
- 100kt per 2 omni-directional weapon battery turrets
- 100kt per omni-directional lance turret (breaking conversion rule, but reasoning later, or perhaps 150kt later)
- 50kt per Torpedo
- 300kt for a Nova Cannon
- 133kt for the Dauntless 33% longer broadside module
Solving for turret sizes
On that omni-directionality point though, I now had another thing to think about. As mentioned previously, I want all the classic Warhammer weaponry to be perfectly usable in Aurora, which of course means they must all appear as some sort of renamed missile weapon. However, since all Warhammer ships also come with a certain turret value that upon closer inspection seemed to be tied to the actual armament of the ship as well, I was now considering a hybrid approach, where a certain amount of the weapon tonnage would be spent for the artillery representation, and and a smaller amount could stand in as the 'short range engagement gunfire mode' of the same weapon. (After all, it would be a shame to have literal "lances" in Aurora and not use them for the Warhammer ships they were meant for, right?)
In that representation, I could easily dual-use these short range weapon tonnages to stand in for the ship's turret rating, since these will all be area defense weapons as the BFG escort rule lore demands.
If you run through the exact numbers, you can find that any x6 macrocannon or x2 lance broadside modules on two sides of a cruiser will also provide 1 turret value.
When you do the same for the escorts however, I found that the provided turret value doubles, as for example the Sword frigate provides 2 turrets with its x4 omni-macrocannons (worth x6 normal macrocannons, which should be worth 1 turret). I am quite happy about this however, as I think it makes perfect sense that the -you know- actual 'turreted' weapons would perform better for point defense purposes. It also fits well with the clear BFG intention of positioning frigates as short range combat and PD escort supports.
Now, to work that relationship in, you just have to acknowledge that whatever percentage of the original 100kt broadsides I set to go to short range / area defense weaponry, must be able to potentially double for the turreted cannon variants.
I found it a neat solution that normal 100kt of broadside should commit 25kt for short range, while 100kt omni-turrets should commit 50kt. Under this setting, one turret rating is 50kt of mission tonnage.
There are some special cases to this, like the Firestorm frigate having to commit 50kt of its mono-directional forward lance to turrets, but it is all within lore assumption of the classes/combat-roles they are supposed to be in.
One last difficulty on the turret point however was that very noticeably every ship with hangars in Battlefleet Gothic had one more turret rating than usual. ...And that is always 1 more, no matter if possessing 2 launch bays or 8 launch bays.
However, ships with carrier capacity seemed to at the same time also be heavier than other ships in their class. For example, the Dictator is 100kt heavier than the Lunar Cruiser, which would roughly be enough to cram another half turret in, considering all the other overhead.
From Defiant Light Cruiser to Emperor Battleship/Carrier, the way to work in turret rating for Launch Bays is never consistent. There is no way to make a rule to use for example 10kt of every 50kt launch bay for defense fire or so, even if the tonnage was constant between the classes, which it isn't.
For now I decided to calculate turret rating as an extra whenever launch bays are involved, and thus just inflate the ship size, which the higher pt cost of all BFG carriers seems to support.
So summarizing the rules here:
- 1 lore Turret rating = 50kt of Aurora beam weapons
- 1x100kt broadside = 1/2 turret rating, which means 75kt to 25kt artillery vs beam weapon split
- 1x100kt turret weapons = 1 turret rating, giving 50kt to 50kt artillery vs beam weapon split
- Agile frigates also treat their lances as omni-directional for this
- Launch bays require extra turret mass above their own weight numbering 50kt + 25kt per broadside they occupy
Engine modeling
There is great freedom on how exactly I want to set the engines up. There are only two setting restrictions that I can see.
1) I must maintain the speed ratios between the capital ships, so for example most battleships will have 15cm (= Speed 3), cruisers and battlecruisers 20cm (=4), frigates 25cm (=5) and the cobra destroyer and possibly some space marine craft 30cm (=6)
2) A very specific exemption places the Dauntless Light Cruiser at frigate speed with 25cm, but at the same time describes it in lore as "having extended supplies and range". That means that -in contrast to frigates- I can't just turn up the burn rate of the same engines, since that would greatly reduce range. Instead I will have to increase the engine mass ratio on this one, while possibly also granting more space for fuel and engineering. Tricky to find a ratio and power factor combination that can exactly generate x1.25 speed with both methods.
Since all Warhammer ships are considered baseline slower, and -as described above- they will all be long-range artillery ships anyway, I settled for a base engine ratio of only 0.3.
Under this ratio I looked at the possible power factors of P0.6, P0.8 and P1.0 and found sets for all that could satisfy the two rules above:
0.6|
Since the P0.8 basis offers an acceptable engine percentage solution for the Dauntless class, seems to strike a balance between fuel economics and speed, and also allows me to design civil craft that can somewhat hope to catch up, I have decided that the engine basis for imperial ships shall be:
0.3 engine ratio with x0.8 power factor
Armor and Shields
The exact sizing here is the most up to debate, simply because it is utterly arbitrary considering there is no clear numerical reference. For armor I only saw one modeling restriction that builds like this:
- 5+ armor models survive 50% longer than 4+ armor models, so they must have approximately x1.5 as much armor percentage.
- 6+ armor models survive 200% longer than 4+ armor models, so they must have x3 as much.
- 5+ armor models with a 6+ prow have 50%x3/4 + 200%x1/4 = ~100% more durability, so twice as much armor percentage as a destroyer or merchant ship.
Battlefleet Gothic and Rogue Trader then will have you believe that shields only come in full values independent of ship sizes, which I find difficult to model. Going strictly it could mean that for example a frigate would have 5% shield tonnage ratio if I set a 30kt basis as "1 Shield" per lore. But under this a x5 sized cruiser would only have 2x1=2%, which seems too little and wasted potential. Running the numbers so far shows that a frigate is much more starved for space than a large cruiser to begin with, but I will see.
For now I have thus opted to have 'hull percentage per shield' rule. Since that doesn't sit well with the lore, I might still change it however. Final decision comes down to how well I can make destroyers and frigates perform using one rule or the other.
For now the shield and armor rules are:
- 4% tonnage base armor, multiplied by 1.5, 2 or 3 depending on model lore armor strength
- 2.5% tonnage shields per lore shield
Last one might change to
- 30kt shield tonnage per 1 lore shield value
-----
I have already calculated through most of the classes I want to use up to battlecruisers with these rules, and they seem to fit. I am running out of time for today though, so either later, or maybe if I document the actual game.
WH40k Ship Builder.xlsx
Hangar/Launch Bay logical basis
I've finally settled on the 1/10 conversion factor after rummaging through the Rogue Trader and Battlefleet Gothic statistics to see if I could make it round. Remember that the fall and feasible here relies entirely on the hangar bay sizes, since that is the one tonnage that can be expressed in clear numbers in Aurora. From there you just look up conversion ratios of Launch Bays to other armaments.
There has been some change however that came from me forgetting a crucial thing about Warhammer ships: While Launch Bays can "fire" from wherever they are on the ship, the broadsides they replace on the models can only ever show one side to the enemy.
Previously I was thinking that a set of 3 squadrons of either 20x1kt size fighters and 10x2kt size bombers would combined with some magazines and fuel make for a good 100kt per Launch Bay modeling basis.
Well, since I can now however only legally count one side of weapon broadsides for engagement, and it is reasonable to assume hangars to be somewhat more empty, I have a good deduction for why I can come back to completely normal fighter and FAC sizes with 20x500t and 10x1kt for fighters and bombers.
One launch bay under this reasoning basis would be 50kt.
Hangar to Weapon conversion factor finalization
Though I did find consistent conversion patterns to batteries or lances, and even had a scipy regression algorithm confirming the same ballpark region, it eventually dawned on me that the few outstanding contradictions (e.g. the Defiant Light Cruiser) could be resolved by a simplification that should have been obvious from the beginning:
Instead of making a set of equations like
- 3 short range monodirectional weapon batteries (WBSRM) = 1 Launch Bay (=2 on broadsides aka 100kt)
- 1 short range monodirectional lance battery (LASRM) = 1 Launch Bay (=2 on broadsides aka 100kt)
...I could just acknowledge that the launch bays take up the same space on the models as one of those sets of weaponries every time, and thus should roughly just take up as much tonnage. Also, although I found the pattern where lower range weaponry converts to higher range with the factor 2/3rd (e.g. 3 WBSRM = 2 WBMRM), that merely relates to salvo density, not tonnage. It will be considered for modelling the munition size and launcher-to-magazine ratios later, but has nothing to do with the correct mass factor deliberation. Under those two assumptions, all inconsistencies to official data are settled for broadsides.
That is different the switch from mono-directional weaponry to omni-directional one. Evidenced by the Sword and Firestorm Frigate designs, which switch 2WBSRO to 1 LASRM while maintaining all other stats the same (pt cost, mass, turrets, etcetc), there also is a 2/3rd conversion factor here, since weapon batteries convert to lances 3:1 otherwise with perfect consistency. So 2 WBSRO = 3 WBSRM = 2 Launch Bays, which is the reasoning path that now confirms the tonnages for dorsal weaponries that don't have hangars for direct comparison.
Applying all deduction above and also considering 1:2 conversion cases between LASRM and Torpedoes, as well as 6:1 Torpedoes to Nova Cannons, the final weapon tonnage rules are:
- 100kt per broadside module on cruisers (whether weapon batteries or lances)
- 100kt per 2 omni-directional weapon battery turrets
- 100kt per omni-directional lance turret (breaking conversion rule, but reasoning later, or perhaps 150kt later)
- 50kt per Torpedo
- 300kt for a Nova Cannon
- 133kt for the Dauntless 33% longer broadside module
Solving for turret sizes
On that omni-directionality point though, I now had another thing to think about. As mentioned previously, I want all the classic Warhammer weaponry to be perfectly usable in Aurora, which of course means they must all appear as some sort of renamed missile weapon. However, since all Warhammer ships also come with a certain turret value that upon closer inspection seemed to be tied to the actual armament of the ship as well, I was now considering a hybrid approach, where a certain amount of the weapon tonnage would be spent for the artillery representation, and and a smaller amount could stand in as the 'short range engagement gunfire mode' of the same weapon. (After all, it would be a shame to have literal "lances" in Aurora and not use them for the Warhammer ships they were meant for, right?)
In that representation, I could easily dual-use these short range weapon tonnages to stand in for the ship's turret rating, since these will all be area defense weapons as the BFG escort rule lore demands.
If you run through the exact numbers, you can find that any x6 macrocannon or x2 lance broadside modules on two sides of a cruiser will also provide 1 turret value.
When you do the same for the escorts however, I found that the provided turret value doubles, as for example the Sword frigate provides 2 turrets with its x4 omni-macrocannons (worth x6 normal macrocannons, which should be worth 1 turret). I am quite happy about this however, as I think it makes perfect sense that the -you know- actual 'turreted' weapons would perform better for point defense purposes. It also fits well with the clear BFG intention of positioning frigates as short range combat and PD escort supports.
Now, to work that relationship in, you just have to acknowledge that whatever percentage of the original 100kt broadsides I set to go to short range / area defense weaponry, must be able to potentially double for the turreted cannon variants.
I found it a neat solution that normal 100kt of broadside should commit 25kt for short range, while 100kt omni-turrets should commit 50kt. Under this setting, one turret rating is 50kt of mission tonnage.
There are some special cases to this, like the Firestorm frigate having to commit 50kt of its mono-directional forward lance to turrets, but it is all within lore assumption of the classes/combat-roles they are supposed to be in.
One last difficulty on the turret point however was that very noticeably every ship with hangars in Battlefleet Gothic had one more turret rating than usual. ...And that is always 1 more, no matter if possessing 2 launch bays or 8 launch bays.
However, ships with carrier capacity seemed to at the same time also be heavier than other ships in their class. For example, the Dictator is 100kt heavier than the Lunar Cruiser, which would roughly be enough to cram another half turret in, considering all the other overhead.
From Defiant Light Cruiser to Emperor Battleship/Carrier, the way to work in turret rating for Launch Bays is never consistent. There is no way to make a rule to use for example 10kt of every 50kt launch bay for defense fire or so, even if the tonnage was constant between the classes, which it isn't.
For now I decided to calculate turret rating as an extra whenever launch bays are involved, and thus just inflate the ship size, which the higher pt cost of all BFG carriers seems to support.
So summarizing the rules here:
- 1 lore Turret rating = 50kt of Aurora beam weapons
- 1x100kt broadside = 1/2 turret rating, which means 75kt to 25kt artillery vs beam weapon split
- 1x100kt turret weapons = 1 turret rating, giving 50kt to 50kt artillery vs beam weapon split
- Agile frigates also treat their lances as omni-directional for this
- Launch bays require extra turret mass above their own weight numbering 50kt + 25kt per broadside they occupy
Engine modeling
There is great freedom on how exactly I want to set the engines up. There are only two setting restrictions that I can see.
1) I must maintain the speed ratios between the capital ships, so for example most battleships will have 15cm (= Speed 3), cruisers and battlecruisers 20cm (=4), frigates 25cm (=5) and the cobra destroyer and possibly some space marine craft 30cm (=6)
2) A very specific exemption places the Dauntless Light Cruiser at frigate speed with 25cm, but at the same time describes it in lore as "having extended supplies and range". That means that -in contrast to frigates- I can't just turn up the burn rate of the same engines, since that would greatly reduce range. Instead I will have to increase the engine mass ratio on this one, while possibly also granting more space for fuel and engineering. Tricky to find a ratio and power factor combination that can exactly generate x1.25 speed with both methods.
Since all Warhammer ships are considered baseline slower, and -as described above- they will all be long-range artillery ships anyway, I settled for a base engine ratio of only 0.3.
Under this ratio I looked at the possible power factors of P0.6, P0.8 and P1.0 and found sets for all that could satisfy the two rules above:
0.6|
Code: [Select]
EN3 - 0.3 with P0.45
EN4 - 0.3 with P0.6
EN5 - 0.3 with P0.75 or 0.45 with P0.5
EN6 - 0.3 with P0.9
0.8|Code: [Select]
EN3 - 0.3 with P0.6 or 0.2 with P0.9
EN4 - 0.3 with P0.8 or 0.4 with P0.6 or 0.2 with P1.2
EN5 - 0.3 with P1.0 or 0.4 with P0.75 or 0.5 with P0.6
EN6 - 0.3 with P1.2 or 0.4 with P0.9 or 0.45 with P0.8
1.0|Code: [Select]
EN3 - 0.3 with P0.75 or 0.25 with P0.9
EN4 - 0.3 with P1.0 or 0.4 with P0.75
EN5 - 0.3 with P1.25 or 0.5 with P0.75
EN6 - 0.3 with P1.5 or 0.45 with P1.0
Since the P0.8 basis offers an acceptable engine percentage solution for the Dauntless class, seems to strike a balance between fuel economics and speed, and also allows me to design civil craft that can somewhat hope to catch up, I have decided that the engine basis for imperial ships shall be:
0.3 engine ratio with x0.8 power factor
Armor and Shields
The exact sizing here is the most up to debate, simply because it is utterly arbitrary considering there is no clear numerical reference. For armor I only saw one modeling restriction that builds like this:
- 5+ armor models survive 50% longer than 4+ armor models, so they must have approximately x1.5 as much armor percentage.
- 6+ armor models survive 200% longer than 4+ armor models, so they must have x3 as much.
- 5+ armor models with a 6+ prow have 50%x3/4 + 200%x1/4 = ~100% more durability, so twice as much armor percentage as a destroyer or merchant ship.
Battlefleet Gothic and Rogue Trader then will have you believe that shields only come in full values independent of ship sizes, which I find difficult to model. Going strictly it could mean that for example a frigate would have 5% shield tonnage ratio if I set a 30kt basis as "1 Shield" per lore. But under this a x5 sized cruiser would only have 2x1=2%, which seems too little and wasted potential. Running the numbers so far shows that a frigate is much more starved for space than a large cruiser to begin with, but I will see.
For now I have thus opted to have 'hull percentage per shield' rule. Since that doesn't sit well with the lore, I might still change it however. Final decision comes down to how well I can make destroyers and frigates perform using one rule or the other.
For now the shield and armor rules are:
- 4% tonnage base armor, multiplied by 1.5, 2 or 3 depending on model lore armor strength
- 2.5% tonnage shields per lore shield
Last one might change to
- 30kt shield tonnage per 1 lore shield value
-----
I have already calculated through most of the classes I want to use up to battlecruisers with these rules, and they seem to fit. I am running out of time for today though, so either later, or maybe if I document the actual game.