On the Economics of Fuel Economy

[skoormit (OP)]

Did you come to this conclusion by analysis, or by intuition and experience?

...It is a balance of different factors which defies general analysis and often defies specific analysis as well, at least if you want to spend more time playing the game than doing math.

I literally started this thread with a specific analysis, or at least an attempt, taking into consideration the different factors in play at a single point in time in my specific game.

Sometimes doing the math is just an extension of playing the game.
For me, anyways.

I would love to know *why* a tug size of 1/3 is ideal (or if it really is).
I understand it's a tradeoff.
Speed vs fuel use vs build cost.

I'm not asking anyone to do more math.
I'm just asking if they have done more math, and if so, will they share.

[Jorgen_CAB]

Well... 1/3 engine is not always optimal... it depends on the engine technology or rather the engine cost. If you look at a standard transport for example...

Nuclear thermal engine transports. The below ships are 100kt cargo, 50 billion range with different total engine (50% power) size.

NT 20% engine size, speed 486km/s cost 896BP (312 Gallicite), 1.84 BP per speed (0.64 Gallicite per speed)
NT 30% engine size, speed 753km/s cost 1241BP (562 Gallicite), 1.65 BP per speed (0.74 Gallicite per speed)
NT 40% engine size, speed 999km/s cost 1659BP (875 Gallicite), 1.66 BP per speed (0.87 Gallicite per speed)
NT 50% engine size, speed 1271km/s cost 2325BP (1375 Gallicite), 1.83 BP per speed (1.08 Gallicite per speed)

The NT ships above should be more expensive as the armour technology was too high so the engine portion cost is too high in general, but still it is a relatively good comparison. So the TN ship above should in general favour slightly bigger engine portion for efficiency.


 Below are the same ship just swapped out the NT engine with an ION version.

ION 20% engine size, speed 1217km/s cost 1369BP (781 Gallicite), 1.12 BP per speed (0.64 Gallicite per speed)
ION 30% engine size, speed 1888km/s cost 2079BP (1406 Gallicite), 1.10 BP per speed (0.74 Gallicite per speed)
ION 40% engine size, speed 2498km/s cost 2977BP (2187 Gallicite), 1.19 BP per speed (0.87 Gallicite per speed)
ION 50% engine size, speed 3177km/s cost 4387BP (3437 Gallicite), 1.38 BP per speed (1.08 Gallicite per speed)

The trend is... the more expensive the engine the less efficient it is to have a larger engine in the Transport ship.. obviously there is still the benefit of getting things faster to the point of interest so speed still have some advantage, especially in very long travels. The longer the trip the more benefit fast ships will become. I also included the Gallicite cost per speed as well as that can be quite important at times as well, at least as much as the total build cost.

If you then swap out the 50% powered ION engine for a 30% power ION engine you can have a slightly higher engine portion for the more efficient ship and better fuel economy and much cheaper ships so way more efficient in BP per speed, thus more transport ship. The 30% ION engine actually is just a tad bit cheaper than the 50% NT engine but 50% more powerful (56 BP versus 62 BP). The best BP per speed for the 30% engine gets down to about 0.95 BP per speed at around 35% engine and speed around 1500km/s. More importantly the Gallicite cost for the 30% powered engine is only about 0.48 Gallicite per speed, so substantially cheaper than the more powerful engine.

 This is obviously not the same as a TUG as that have different priorities.