better engine efficiency vs power & fuel considerations

[letsdance (OP)]

i'll explain my problem with an example. in the ship designer i design a ship that has 25,500 tons without engine. i picked an empty ship with one terraforming module, and 1 fuel storage (50,000 litres). but it doesn't matter how the ship looks like (instead of the terraforming module you can use total 500 HS of war tonnage if you prefer). total ship size does not matter for this either, but for ships below 5,000 tons it can be even more efficient to use one larger (higher HS) engine to also take advantage of the fuel modifier (see my other thread concerning engine efficiency for that).

then i have to decide on the engine. my technology is solid-core anti-matter drives and fuel consumption 0.25 litres per power hour. the relative results will be the same if you have different technologies. i consider 2 different engine designs, both HS 50 (the relative results are the same if you use smaller engines):
#1 engine power x0.25 (power 500) - cost 625 to research and 62.5 to build - using 2 of them
#2 engine power x0.35 (power 700) - cost 1225 to research and 122.5 to build

note: you can use ANY technologies for test designs, i just happen to have these right now - the relative result is the same

two engines #1 cost about the same to build as one engine #2. 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 1,633 kms, range 75b km, total ship size 30,600 tons
#2: speed 1,245 kms, range 35b km, total ship size 28,100 tons

surprise! #1 is cheaper to research and costs the same to build. but the ship is faster and needs less than half the fuel (more than double range). shouldn't the more powerful engine make the ship faster? (or at least, give any advantage)

well if we want a faster ship, lets try doubling the engine number, now we're either using 4 engines #1 or 2 engines #2:
#1: 2,805 kms, range 65b km, total ship size 35,650 tons
#2: 2,287 kms, range 32b km, total ship size 30,600 tons

still the same... double the number of engines again to 8 for #1 and 4 for #2:
#1: 4,366 kms, range 50b km, total ship size 45,800 tons
#2: 3,921 kms, range 27b km, total ship size 35,650 tons

that's pretty fast already and still the only advantages of the faster engine is a lower total ship size and less termal signature(2,800 compared to 4,000). the difference in ship size hardly matters compared to the obvious advantages.

lets double the number of engines again to 16 for #1 and 8 for #2:
#1: 6,060 kms, range 35b km, total ship size 66,000 tons
#2: 6,106 kms, range 22b km, total ship size 45,800 tons

finally!! by now the #1 ship is over 60% just engines, but it is no more faster than #2. though it still needs 30% less fuel, and the research cost was half as much.

the result is pretty much the same for any ship size and power multiplier. a higher power multiplier makes the ship only faster, if engines are at least 50 % of the whole ship.

to sum it up: i would like to see more reason for using more powerful engines. a simple solution would be to make all engines of same size have the same build costs, independent from the power multiplier.  this way, engine stacking at least makes your ships more expensive.

there is another problem: comparing examples 1 and 2 doubling the amount of engines, i only need 10% more fuel to travel the same distance with 75% higher speed. if we compare examples 1 and 4, the speed is about 4 (5) times higher and the fuel needed increased by about 100% (50%) for engine #1 (#2). now that's an efficient power vs fuel usage ratio! there's hardly a reason to build slow ships if we can make them twice as fast by only needing 10 % more fuel.

the problem comes from aurora putting very different weight on speed vs fuel considerations. while in the case of using multiple engines you get higher speed for very little fuel, it's extremely expensive in the case of using more powerful engines.

i suggest to reduce the impact of the engine power multiplier on fuel usage. currently, every 100% increase in power increases the fuel per EPH by 566%. that means you need 11 times as much fuel to travel the same distance in half the time. i suggest to increase the fuel per EPH only by 200% for each 100% increase in power. that still means, to travel the same distance in half the time you need 4 times as much fuel. or you can save 75% fuel by using engines of half the power.

this would make engine stacking much less efficient and give higher power engines more use. it would also need some testing to find out if my suggested values are good and how it influences total fuel needed. i am willing to help if possible.

i also suggest remove the fuel consumption tech line, or make it much more expensive (in the way that you get the lower multipliers much later). better engines already help you save fuel because they increase ship size less for the same engine power. and you also have the advantage of getting fuel more easily at higher tech levels. keeping a big fleet supplied with fuel should be a real challenge!

finally, fuel weight should be increased. i guess the weight for the fuel is included in the HS of fuel tanks (that's exactly 1kg per litre). currently, it's not much of a problem to give all ships the range that you want them to have. even with my suggestions above, fuel tanks just don't need enough hull size to really matter. trippling or quadrupling the HS of fuel storage components would make range considerations more important. it seems reasonable that such powerful fuel as used in trans-newtonian engines have higher density than our modern fuels. this suggestion is independent from the rest.

[letsdance (OP)]

JacenHan pointed out that more engines mean higher chance for engine explosions.

i'm undecided, or rather, i'm lacking the knowledge to judge this. but more engines also mean more total HTK and it doesn't matter as much if you lose one of them. higher speed means better evasion and more tactical options. besides this, the advantages of using a higher number of lower power engines are so big, that you can put more armor (or shields) on your ship and still be faster. but then it also becomes more expensive.

if larger ships were easier to hit it would also solve or mitigate the problem.

[alex_brunius]

my technology is solid-core anti-matter drives and fuel consumption 0.25 litres per power hour. the relative results will be the same if you have different technologies.

So in short you are using extremely low powered engines and extremely advanced technology levels that pretty much never is an actual choice.
No one would design a warship with that tech level and speeds of only 1000-6000 km/s, so your entire example is one of theory and fantasy only that never really will be relevant to warship design in the game.

lets double the number of engines again to 16 for #1 and 8 for #2:
#1: 6,060 kms, range 35b km, total ship size 66,000 tons
#2: 6,106 kms, range 22b km, total ship size 45,800 tons

finally!! by now the #1 ship is over 60% just engines, but it is no more faster than #2. though it still needs 30% less fuel, and the research cost was half as much.

You also kind of forgot that option 1 requires a 44% larger military shipyard... And should be more expensive + time consuming to build.
Also research cost of components is negligible at the tech levels when you have 0.25 litres per power hour and solid core AM drives...

[Haji]

to sum it up: i would like to see more reason for using more powerful engines.

I don't know how your games usually progress, by in my case I always have problems with the shipyard capacity and I always design commercial ships to the maximum size allowed by my shipyards (bar some very special circumstances). Since the space is limited, more powerful engines are usually the only way for me to increase the speed of my vessels (at the price of slightly larger production costs, much larger fuel consumption and more limited range). As speed in incredibly important for the growth of your empire, especially early game, there are plenty of reasons to build more powerful engines, even if this increases the costs of the ships. This is especially true since for practically anything other than freighters the engine costs are quite low compered to the total cost of the ship, usually being in the vicinity of 5%-12% of the total ship cost. (For commercial vessels; for military ones it's a somewhat different story.)

[letsdance (OP)]

So in short you are using extremely low powered engines and extremely advanced technology levels

its the same for all tech levels. it's the same for all engines power and fuel usage multipliers. and there's not only military ships in the game.

you can just half all ranges (adjusted to fuel consumption 0.5) or quarter them (adjusted to fuel consumption 1.0). then half all speeds (adjusted to internal confined fusion drive) or set them to 30 % (adjusted to ion drives). double all speed values while reducing range to 9 % (adjusted to engine powers 0.5 and 0.7); or quadruple them and reduce range to 0.8 % (adjusted to engine powers 1.0 and 1.4). you can also half the ships size and use only half the number of engines, or quarter both. it's all the same.

[alex_brunius]

and there's not only military ships in the game.

For balancing issues only military ships are important.
Civilian shipping lines can handle all your colony and building lifting without costing a single drop of fuel or industry to build. I promise you zero fuel and industry cost is vastly more efficient then any design you can dream up

half all ranges.... half all speeds... half the ships size... it's all the same.

Huh? Changing the ranges, speeds and size of ships is not the same example anymore, it's a different example with different values.

Especially when you take everything else into account like armor which is a bigger penalty for big ships if your level is bad and so on. Or mandatory components like the bridge that will add x tons instead of x% regardless of how small or big you make the ship.

[letsdance (OP)]

I always have problems with the shipyard capacity and I always design commercial ships to the maximum size allowed by my shipyards (bar some very special circumstances). Since the space is limited, more powerful engines are usually the only way for me to increase the speed of my vessels.

give me an example and i'll give you the solution. what tech level (engines, fuel consumption, minimum engine power modifier) are you talking about, what's the total tonnage of your commercial ship (what ship are we talking about anyways?) and what engines are you using?

[letsdance (OP)]

For balancing issues only military ships are important.

i don't agree, but it's the same for military ships anyways.

[Haji]

give me an example and i'll give you the solution. what tech level (engines, fuel consumption, minimum engine power modifier) are you talking about, what's the total tonnage of your commercial ship (what ship are we talking about anyways?) and what engines are you using?

You know I was thinking about providing you one, but... what for? I mean, my whole point what that your making an argument made purely on production and research costs. And as far as it goes you're right, you can make ships cheaper and faster using lower powered engines. But you're not taking into the account the situation in which the ships are being designed. I'm talking here about economy, politics, time constrains, shipyard and mineral availability, fluff, role-playing, fuel availability, distances and other things. To put it simply, I never play Aurora as a single player game, I'm always role-playing multiple nations and in such situation shaving 5% construction costs of my ship is usually poor second (or third) to all the other considerations like a need to get my ship to that cool planet sooner than the other power can do so, so I can claim it. And that's just one example. To be honest, as soon as my fuel shortages are solved, I always use 0.5 power commercial engines, simply because whoever has faster ships has advantage in establishing his or her empire, which is very important when you're playing six power blocks starting in the same system all competing for the same resources and all being afraid of being attacked if they cannot build a big enough navy fast enough, which requires them to quickly tap the needed mineral deposits and build as much as possible as soon as possible, without waiting for larger yards to build cheaper ships.

But that's how I play my game and why I use more powerful engines. If you're playing your game differently then yes, you may find low powered engines much more useful and compelling - which is the beauty of Aurora, as it allows all of us to play the game the way we like.

[letsdance (OP)]

I'm talking here about economy, politics, time constrains, shipyard and mineral availability, fluff, role-playing, fuel availability, distances and other things.

economy, politics, fluff, role-playing... this thread is about improving game mechanics.
shipyard availability... yes thats an issue, but a small one, especially for commercial ships that can often be designed smaller without losing anything
mineral availability... less powerful engines need exactly the same minerals (amount and type)
fuel availability, distances... if that's bad it's one more reason to use less powerful engines

a need to get my ship to that cool planet sooner than the other power can do so, so I can claim it.

sounds like a faster design, that uses an engine which is quicker to research would support this. one more reason to optimize designs the way i described it.

as soon as my fuel shortages are solved, I always use 0.5 power commercial engines, simply because whoever has faster ships has advantage in establishing his or her empire

isn't it a bit boring, that you're using only one choice of the huge amount that the engine design offers? my suggestion is all about making more options interesting. it seems that might be an improvement also for your play style.

[Whitecold]

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%, which is nowhere near free, requiring a lot of population and resources. In fact, tonnage is the first thing that get fixed for any of my designs.

Second the fact that you use high tech engines for your example is relevant. 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, and being faster than your opponent is a massive advantage in battle.

[crys]

you make some mistakes here.

this seems to look only at fuel use. otherwise you could use stronger smaller engines.

you have one fixed statt which is youre shipyard size, sure you can make it bigger but that has advantages as well as disadvantages.

so lets say you have a 300k shipyard.

just with one engine type you have now a function between engines and gain.

you could see the gain like speed * cargo - and max this function.
however costs and fuel use are interesting too. you might want to max thouse too.

now you could use different engines in this function too, smaller more powerfull engines, which make you faster.
they might even make the ship cheaper, but use more fuel.

maybe a huge slow ship can haul more over time, but you want to wait so long for a haul.


now there is something compleatly different military ships. thouse ships need armor, and the shipyard is much more expancive.
youre huge engines would add alot of armor-mass which might make them less effective.
im not sure about repairs with thouse huge engine, and how they work with engeneering spaces.
huge ships make youless difficult to hit and scann too.

so this is a very difficult question.


but i have to agree, the fuel consumption advantages of huge engines are a bit too strong.

[letsdance (OP)]

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)

[alex_brunius]

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.

22% Larger shipyard to be exact, and this is for a gain in speed of 4.8%...

So lets compensate for this effect as you say by instead building 22% more ships of same tonnage. But that doesn't really help us because adding slipways is equally time and resource consuming as expanding the shipyard is ( if not more ).

but if we consider infrastructure you also need less fuel refineries, sorium and tankers (which also need shipyard capacity to build).

Tankers and sorium refiners are civilian designs, which is mostly irrelevant for how much Military shipyards you need for your military designs.



So if we are to summarize we can say that using more engine tonnage and lower powered engines instead is a valid choice that makes sense if you are not restricted by buildtime or shipyard/slipway size, but instead are having problems with range or fuel consumtion. Especially for civilian designs where it's cheap to expand the shipyard and fuel consumption is normally an important metric.

It is however not always an option. Especially for many smaller military designs ( fighters, FAC, offensive destroyers/scouts or beam warships ) that need so high speed that a low powered engine would leave them with zero mission tonnage.

[letsdance (OP)]

yes we can agree to that. but i would still like to see senseful ship designs that consist to a lesser percentage of engines.