Fuel consumption suggestion

[alex_brunius]

Yes, it's embarrassing when you find out that one of your survey ships does not have enough fuel to return home. I doesn't matters how fast or slow it will go, it will only reach one point in space.
Each ship has an optimal cruising speed in reality, so we only need a chart to define that.

Acutally a formula is what's needed since the game needs an answer for any manually input speed % of max.

I would suggest the simple one that range is increased by the same factor that speed is cut.

So at 50% speed a ship get twice the range (consumes 25% fuel)

If the ship instead had an engine tuned for that speed it would have a fuel efficiency much greater.

This solution would also allow your ships to almost always slowly hobble home at significantly reduced speeds paying in time (and maintaincence failures if military) for their lack of fuel.

[bean]

Looking through some stuff I have on naval architecture, it appears that scaling with the square of speed is correct, except that there are some confounding factors which go down at higher speeds.  The best relationship I can work out based on the explanation Steve gave (ships operating in parallel-dimension fluid medium) is that drag will scale with velocity to the 1.5 power.  This actually appears quite reasonable, as doubling speed will require a thrust increase of a factor of 2.828.  Theoretically, power required is going to equal thrust (which must equal drag) times velocity.  This in turn means that doubling speed will require that power increase by a factor of 5.657.  A better option is simply to replace power with thrust in the documentation, and have fuel usage be proportional to thrust.  This is basically how a jet engine works.

[SteelChicken]

While I think the new fuel model is a bit...over the top when it comes to fuel consumption, you already have the ability to build ships and engines with fuel efficiency in mind.  Just don't expect your highly overpowered military engine to get great gas mileage.  Research the appropriate tech and design engines accordingly.  I use commercial engines in my survey ships so I can keep them out there for 3-4 years 200-300 billion km's of range.  Also, you can't just send your massive battle fleet 4 sectors away, fight a battle, and return without refueling anymore.  Bring fuel with you or setup a depot nearby.   No big deal.

[Falcon]

Actually there is a way to move military ship in a fairly cheap manner - tugs. Create uber efficient engines, put them in a big civilian hull with a tractor beam. That ship will then be able to slowly tow your ships wherever you want. The only problem is that it's going to drive you mad with micro management.

 

[alex_brunius]

Looking through some stuff I have on naval architecture, it appears that scaling with the square of speed is correct, except that there are some confounding factors which go down at higher speeds.  The best relationship I can work out based on the explanation Steve gave (ships operating in parallel-dimension fluid medium) is that drag will scale with velocity to the 1.5 power.  This actually appears quite reasonable, as doubling speed will require a thrust increase of a factor of 2.828.  Theoretically, power required is going to equal thrust (which must equal drag) times velocity.  This in turn means that doubling speed will require that power increase by a factor of 5.657.  A better option is simply to replace power with thrust in the documentation, and have fuel usage be proportional to thrust.  This is basically how a jet engine works.

You don't want to have lower speeds reduce fuel consumption by the same factor a more efficient engine would do.

That would make engine design mostly irrelevant since an engine with maximum power can throttle down to be identically efficient with any other engine possible to design of the same size (and tech)!!!

[bean]

You don't want to have lower speeds reduce fuel consumption by the same factor a more efficient engine would do.

That would make engine design mostly irrelevant since an engine with maximum power can throttle down to be identically efficient with any other engine possible to design of the same size (and tech)!!!

Under my proposed model, the actual fuel efficiency (total range) goes up by a factor of two if you cut speed by a factor of four.  This is because you're using half the power (thrust) per unit speed at 1/4 speed as you are at full speed.  A ship designed for the 1/4th speed would need 1/8th the power/thrust of the faster ship.  Assuming the engines are the same size, the slower vessel will have a fuel efficiency that is 181 times that of the faster vessel. 
In other words, it's not even remotely like what you propose.  An interesting side-effect is that speeds will tend to bunch closer together, as the marginal cost of speed goes up.  This is not at all unrealistic when looking at real ships.  One possible idea to implement alongside this is a "natural speed" technology which defines the point at which the new model crosses the old.  Any ship below that speed will see its speed go up under the new model, while any above it will see a drop.  The technology (something like "Trans-Newtonian Streamlining") would increase the natural speed, and allow higher-tech ships to go faster for the same power.  This is mostly to counter the exponent in the formula, which would impose a serious limit on higher speeds otherwise.

[alex_brunius]

Ah okay then I just got confused when you started writing stuff about the fuel efficiency already in the game, especially this part:

"better option is simply to replace power with thrust in the documentation, and have fuel usage be proportional to thrust."


Why didn't you just write that you suggest the same thing I did one post above yours?

[bean]

Ah okay then I just got confused when you started writing stuff about the fuel efficiency already in the game, especially this part:

"better option is simply to replace power with thrust in the documentation, and have fuel usage be proportional to thrust."

I'm an engineer.  I was working it out as if we were dealing with real physics. 

Why didn't you just write that you suggest the same thing I did one post above yours?

Because I didn't.  I suggested that we implement a specific formula, which is significantly different from "have fuel use scale with thrust fraction."

I'm now going to look a little more at my proposed model.  All calculations are made on the basis that all ships have the same engine sizes and fractions, and the same fuel fraction.
One thing that would significantly enhance the model is to have fuel economy scale with (power modifier)^(5/3).  This means that, for any ships traveling at the same speed, the relative ranges will be the same as they are in the current version of Aurora.  Right now, a ship designed for a speed x will have 32 times the range of a ship designed for 4x.  If we keep the same fuel model and implement my proposal, the relative ranges for both ships at speed x will be different by a factor of 181.  If we alter the fuel model, the difference goes back to 32.  On the other hand, under my model, the 4x ship at maximum speed will have a range that is 1/64th that of the x ship. 
Alternatively, an exponent of 5/4 would give the x ship 32 times the range of the 4x ship at maximum speed for both, and 16 times the range at speed x.  That actually sounds like a better plan, extending the range of faster ships at lower speeds instead of penalizing them at higher speeds relative to the current model.
There would probably need to be greater variance in the power modifiers to achieve similar results to the current system.  The maximum a vessel can do is 3x what a non-modified vessel could do.  To preserve this, the maximum power modifier would have to increase to 5.196, which can safely be rounded to 5.2.
The overall impact with these changes would be minimal, except for allowing cruising at lower speeds.

[TheDeadlyShoe]

I don't really see the point.  You're always going to throttle up for combat and throttle down for cruising.  And combat doesn't typically last long enough to make a difference to fuel levels.   If  the math is adjusted so that it doesn't make a difference to overall range (-->cruising speed range) than all you're doing is adding some additional micro to combat and slowing ships down overall.   It's already hard enough to expand to other systems without cutting ship speeds.  The first time a battlegroup gets stranded because I left it on combat speed, I'm going to be pissed. ^_^

[bean]

I don't really see the point.  You're always going to throttle up for combat and throttle down for cruising.  And combat doesn't typically last long enough to make a difference to fuel levels.   If  the math is adjusted so that it doesn't make a difference to overall range (-->cruising speed range) than all you're doing is adding some additional micro to combat and slowing ships down overall.   It's already hard enough to expand to other systems without cutting ship speeds.  The first time a battlegroup gets stranded because I left it on combat speed, I'm going to be pissed. ^_^

That's why I'm in favor of 5/4 as opposed to 5/3.  Your combat speed range is the same and you gain in cruising speed range.
Of course, it gets more complicated when you go to different engine fractions.  Then, the benefits are less dramatic.