this seems to look only at fuel use. otherwise you could use stronger smaller engines.
maybe you should read my post. i'm looking mostly at speed. the saved fuel is just a convenient side effect.
maybe a huge slow ship can haul more over time, but you want to wait so long for a haul.
not it can't. never. it's alwas better to make it faster the way i described it. i wish it was different because i like the idea of huge slow ships. but it makes no sense in aurora. give me an example (tonnage/carge space, engines used) and i show you how to improve it.
letsdance, first you are ignoring size restrictions. Shipyards are not free, getting my 25% 1x engine designs to 50% 0.5x engines would require to expand my shipyards by 50%
i only see a 25 % expansion here, not 50. and you can also take advantage if you increase your engine % by only 10. but yes, you need either a bigger shipyard, or build a larger number of smaller designs (which is quite often a valid option without losing anything). it's worth it. for smaller ships (for example 3,000 tons) a 25 % increase in shipyard requirements doesn't really matter.
Each engine has a limiting speed of a 100% engine design, which is directly proportional to the engine multiplier. Your ships pull 6kkm/s, what if I want 12kkm/s? You won't be able to reach it with these designs
yes, using lower power engines makes only sense as long as your ship is less than 50 % engines. but that was exactly my point: every ship should be 50 % engines. that's boring.
Second the fact that you use high tech engines for your example is relevant.
no it's not. the effect is weaker, but it's still there. to end the discussion if it's relevant, i give you examples with an earlier tech warship. i will also consider maximum range this time.
the technology used is ion drives, fuel consumption 1 litre per power hour. in the ship designer i design a ship that has 8,000 tons, but so far without engine or fuel tanks. the tonnage can be anything, pick your favorite weapons. i consider 2 different engines (both HS 30):
#1 engine power x0.80 (power 480) - cost 1,920 to research and 192 to build
#2 engine power x1.25 (power 750) - cost 3,750 to research and 375 to build
two engines #1 + 100,000 litres fuel tank cost about the same to build as one engine #2 + 250,000 litres fuel tank. now lets compare the ships speed and range (which tells us how much fuel it uses) using either 2 engines #1 or one engine #2:
#1: speed 3,622 kms, range 4.7b km, total ship size 13,250 tons
#2: speed 3,456 kms, range 4.7b km, total ship size 10,850 tons
again, #2 is faster, cheaper to research and needs only 40 % fuel. yes, the speed gain is not much... but it shouldn't be there at all! the size increased by about 20 % which means you need a larger shipyard. but if we consider infrastructure you also need less fuel refineries, sorium and tankers (which also need shipyard capacity to build). it's also notable that this is a short range ship. if you need a higher range the advantage of the more efficient engines increases:
#1: speed 3,542 kms, range 18.6b km, total ship size 13,550 tons (fuel tanks 400,000)
#2: speed 3,218 kms, range 17.7b km, total ship size 11,650 tons (fuel tanks 1,000,000)