[discussion] We need to talk about fuel

[Uncle-Ulty]

We need to talk about fuel

Hi Tsuna! Me and Servo were talking about fuel and energy balance in starship EVO.

6 way pipe

First, the 6way pipe connector doesn’t seem to been working properly. Some already said that this is a fuel tank reskin. I don’t know how is it supposed to work in starship evo, so I ran some experiments.

In the current experiment I use a ship (classified) with two identical power systems. One of them is supplied by a tank and straight pipes (the right one in the picture), and the second system is supplied by a tank connected to the reactor with a 6way pipe and pipes (the left one in the picture). If the 6way pipe is trully a reskin tank, so this reactor is using the fuel inside the 6way pipe, and ignoring the upper tank, since the fuel doesn’t flow between adjacent tanks. The bellow figure illustrates what happened after some time.

Fuel consumption

The current fuel consumption is insanely high! I’m using in this example a car-size hovercraft. It’s a 8x3x2 size and 3,8t hovercraft. The current energy balance is 99%, and its fuel consumption is 4,2l/s… We must consider that this is a game, a “futurist” one, but lets compare the number to the reality with some equivalent interpretations. Imagine a car consuming 4,2l liters per second. It means that in one minute this car would consume 252 liters, and this is a lot of fuel! We would consume 252 liters parking our car… these numbers don’t make sense, right? Let’s go further. If the Stevo fuel was gasoline (energy density 34,6 MJ/l), this hovercraft would require to produce 107,3 MW (143.489 hp) to keep running. As a comparison measure, the Itaipu Dam (the second largest dam in the world) has 20x turbines, and each one of them produces 700MW. We could say that this Dam, that supplies all Paraguay and 10% of Brazil’s energy, produces equivalent power of 130 of this starship evo hovercraft.

After these considerations, I think the fuel consumption rate should be reduced by a 5~20 factor to make it more playable. If the reactor uses all its internal fuel in one minute, maybe a 10 factor would make it run for 10 minutes with the same amount of fuel, a decent time. Or you can reduce the fuel rate consumption and also reduce the reactor internal tank.

Fuel in different scales

The 1m reactor brick, forming a 1m³ reactor, has 250l of fuel in its internal tank. Meanwhile the ¼ reactor, forming the same 1m³ reactor, has 1000 l [1m³], that is, the ¼ reactor has its entire volume filled with fuel, as it was a 1m³ fuel tank. it’s a little absurd.

¼ m [1m³] reactor stats

1m [1m³] reactor stats

The ¼ m [1m³] reactor has the same amount of fuel as a 1m³ fuel tank.

These are my considerations. I have a lot to talk about the fuel mechanic, but I think these 3 points are enough for now. Let's see what the player base has to talk about

[tsunamayo]

Thanks for the examples, keep them coming! To be honest those ship looks very specific shape wise, they inner-hull sections are on small size I would say as they are rather sleek. But yes I will reduce consumption by a lot...

[Kaiser-Indrasil]

@tsunamayo Is there an easy way to check the ship's fuel statistics like consumption rate, tank capacity, estimated "battery" time etc.?

Here's my Agni-class fighter with a representation of its reactors and a 4x1x1m fuel tank.

However, the tank is twice the size of what I wanted for it in the end. And it still only lasts about 2 minutes of regular flight. So with smaller tanks it would only last about 1 minute.

And here's a 24 minute-lasting version with 15 times bigger fuel tank (5x4x3m). To be perfectly honest, I would like my fighter to last half an hour with 2000L tank capacity. That means, I think fuel consumption should be reduced 30-40 times.

[TIKIRobo]

naming things is hard (2).zip VanSha - Repair Ship.zip unfortunately i dont have time to check the stats on these two, sorry. they are both smaller ships, the repair ship is meant for short range and so its fuel tanks are intentionally tiny (and maybe a bit too small)

[tsunamayo]

@Kaiser-Indrasil Hi, so I will add more stats for sure, but the fuel economy will always be tough because I cant know how much power you will draw during gameplay. Doing a bit of exploring or doing full-on combat will results in very different consumption. As I can only easily compute 100% of power being drawn any indication would be very low and could scare players...

Here what I would like to do for calibrating fuel:

=> Having a fuel the size of your reactor (built at 1m) will give you average / acceptable range.

So some remarks on this:

• I think having tank of the same size of the reactor is visually okay, and definitely more on the small side and not on the large. It is not like your ship is only made of reactors...
• Now there will be a lot of tweaking of what means acceptable range. I think having to refuel after 30m is a solid basis. Of course as you progress you will build larger ship with larger interior and a larger autonomy so I guess this is a good starting point.
  • I use 1m tank as a unit. First I always needs to use the 1m in my computations. I think it is a good starting base to calibrate as your are not going to build a mini-fighters for survival. Your first ship might be on the small side but as you progress and warp I think player will have 30M+ ships, so I expect the 1m to be a good scale.
  • Right now I just calibrated the stuff so that a 1m reactor can operate 1m on its own 250L internal tank. Yep that is high ^^, but I figured that you are never using 100% of your power all the time, so that 1m could be maybe 5m-10m of gameplay... So a tank of the same size (a 1m = 1T of fuel, 4x more than on the reactor internal) will give you 5X time more, so 25-50 minute of gameplay... (if you think I messed up my computation in-game tell me)

=> Now regarding your (amazing looking) Agni, my problem is you use a very big stack of mini-reactors, and just like I said in my previous comment you will always issues with that.

• your 6400e/s 2mx2mx2m stack of 0.25m is yielding x4 more power than an equivalent size made of 1m reactor.
• Which means you need 4x bigger fuel than the 8T the standard one would need following my 1-to-1 balance rule, which is 32T.
• So according to my calculations, in your case, I need to increase efficiency only by 2x (caveheat it was only range during travel)
• But it depends on how much of the total % power your ship is using on lightcruise thruster. The big thing is that I will have lightcruise use fuel and not (or not much) power. And of course they will only draw fuel when in lightcruise! Which you wont always be... So the way forward is not simply increasing efficiency but also fixing lightcruise engine.
• Also this is why I am considering getting rid of the non-linear rules, I expect people to get frustrated by that. You of course wants more power density but got trapped by that on the fuel side.

I hope the in and out of the fuel / reactor size issues are more clear now... I think I am gonna have to open a discussion on non-linearity and bundle this with the next big fuel update if I have to... Cheers

[ProPeach]

Big thanks for taking the time to explain your thought process, it really focusses the discussion down. Also a nice reminder that the power values we see at the moment aren't always what we'll see in the future as everything is demanding 100% power right now, I guess this will also link into throttle during flight too?

Regarding the non-linearity of systems and how it affects fuel, it's gonna be tough to rule on either side before we can see the impact things like Lightcruise thrusters/warp and fuel scoops have on smaller ships I think. Maybe smaller ships don't necessarily need the larger tanks to keep up with smaller scale systems if they don't need to warp around much, or can refuel reasonably easily at stars? Before those things come into play the discussion might be a lot more theoretical which is not ideal hehe

[tsunamayo]

@Uncle-Ulty Hi, regarding the 250L thing I would need to see the blueprint. The only thing I know is that you used a 1m large reactor (and hence should have 1T tank). I would like to know how the power is spent, it might be about the hover-pod consumption too. Power consumption seems high out of the box.

[tsunamayo]

@ProPeach Yeah exactly... So indeed I want fuel to be easily available at stars. But I my plan was to have the red star give the red low tier red fuel, the blue star would give the blue fuel (and maybe throw a super rare green star in there too ...). Then the blue fuel would be more rare, but more efficient for thrusters. That means that the newcomer dont really care at first, but the advance guy could create two tanks, one red for reactor and a blue for thruster. Then if one get empty, you can have a link between them so you can still operate. I dont want fuel to depend on throttle for non-lightcruise, that would be a bit too cumbersome for the player to manage I guess, what is your take on that? I was just going to have a flat rate for thrusters, but a pretty low one so you do not bother.

Also, as people dont like weapon addons at all and it is honestly not really adding much, I am very much considering putting fuel in the balance for weapons too. That would be quite different to standard fuel, more about the fun of having different fuel yield different damage type, and doing a bit of chemistry to get various bonus combination. I dont want ship to require large amount of fuel for weapon as great fuel will be harder to find (I wanted those to be nebulae based). It would also allow advanced player to build system able to hot-swap fuel for weapons during combat depending on the tactical situation, like first the anti-shield, then corrosive or anti-system, ect. Those could needs to be ionized first, so we could talk about plasma weapons.

I can open another discussion on that one too lol...

[ProPeach]

On the fuel scoop front that sounds good as a basis, it'd be nice if one of the higher tier fuels required some infrastructure in the form of a processor/factory element. For throttle I'd prefer if the energy/heat and therefore fuel consumption scaled with the thruster throttle, so you've got a bit more nuance in how you fly affecting your fuel level. In basis thrusters I guess there are a lot of levels too it, if a thrusters throttle affects its power requirement, that also affects its draw on the reactors which will affect your fuel consumption... Plus you also have the effect on heat, ie with all those systems working harder your ship will run a lot hotter as you go faster. That sounds like a logical progression that I don't think players will have an issue with.

For addons, I actually love the idea of them just not their current iteration ;) I think it's worth it to try changing them a little to be more satisfying before they get removed for a different system all together, especially as addons and fuel could have some really great synergy together. Definitely looking forward to that Dev Asks thread and your thoughts on that.

[Uncle-Ulty]

Hi Tsuna.

this hovercraft is old, from 2020, so I had to update the bp

The situation is worse... Since it's a noncombatant vehicle, it only has a reactor and thrusters. No shields or anything. Its power balance is 96%, and it's consuming 8,3 l/s. This hovercraft requires 14940 liters to work for 30 min, and it means a fuel tank of this size:

VW Gol - racing hovercraft v02.zip

[Kaiser-Indrasil]

@tsunamayo

your 6400e/s 2mx2mx2m stack of 0.25m is yielding x4 more power than an equivalent size made of 1m reactor.

For military craft I always give about 30-40% of power output headroom compared to the max power draw (including the gun recharge), so this kind of power is necessary for me for redundancy. It makes the fighter fully operational even if some of its reactors get destroyed in a fight.

Also, I can't realistically cram more than 2-3 1m reactors into such a lean frame without compromising armour plating. So I need my reactors to be as dense as possible. That's why I used 1/4m reactors exclusively.

With that in mind, I've noticed that the fuel draw is much higher for fuel tanks compared to reactors having the same fuel capacity of 4000L.

https://user-images.githubusercontent.com/63756057/149502913-7c688513-9730-45b1-a082-85aca936cb9a.mp4

I got to the bottom of this, and it seems that, for some weird reason, fuel draw is proportional to... pipe flow rate. Even though the power draw and pretty much everything else is constant. The only thing that pipe flow rate should change, is the rate at which the fuel coming from fuel tanks replenish the fuel in the reactor's tanks. The fuel draw should absolutely remain constant in such case.

https://user-images.githubusercontent.com/63756057/149505212-36bce365-630e-4abe-9c58-32cc8ebf0e68.mp4

Also, I've noticed even more broken thing. The power balance is nearly 1400% and despite this, I can use the fighter and even shoot the guns. Seems like the only limiting factor here is, if the reactors have fuel. Here's the blueprint for the ship I used in the above video.

https://user-images.githubusercontent.com/63756057/149511195-cae9ed02-a7dd-47b9-aaf3-841ca66e15bf.mp4

[Regnion]

This ship would need 90,000L to operate for 30 minutes, because it burns 50L per second. It currently holds 15,210L, giving it like a 5 minute flight time.

As a note, an F-22 Raptor carries about 10,000L internally and can fly for a couple of hours (external fuel tanks are added in peace time for longer duration flight). This ship is about the same length and height as a Raptor (but it is significantly wider). So our gas tanks don't even hold as much fuel as they could.

The four big tank cubes hold, for comparison, 91,128

Also I added a small tank into the ship before taking the pictures, and it caused a sudden power drain. Fuel tanks shouldn't really require much power, if any at all. IRL they're gravity fed, and while we don't have gravity in space, I think the power consumption for tanks should be so negligible as to be not worth calculating in the first place.

[tsunamayo]

This ship would need 90,000L to operate for 30 minutes, because it burns 50L per second. It currently holds 15,210L, giving it like a 5 minute flight time.

As a note, an F-22 Raptor carries about 10,000L internally and can fly for a couple of hours (external fuel tanks are added in peace time for longer duration flight). This ship is about the same length and height as a Raptor (but it is significantly wider). So our gas tanks don't even hold as much fuel as they could.

The four big tank cubes hold, for comparison, 91,128

Also I added a small tank into the ship before taking the pictures, and it caused a sudden power drain. Fuel tanks shouldn't really require much power, if any at all. IRL they're gravity fed, and while we don't have gravity in space, I think the power consumption for tanks should be so negligible as to be not worth calculating in the first place.

Hi, thanks for the see-through screenshots. If you can send me the bp I could use it to get a sense of what I need as it seems to be sensible in term of internal packaging. Now tanks should not consume power, their stats is at 0, so it seems like a bug (I could also try to reproduce the issue on the blueprint). Thanks

[Regnion]

As the @tsunamayo commands, it will be done. See attached.

Regnion Heavy Starfighter Blueprint.zip

Please ignore the trap door inside, it was placed when doors were busted. I wasn't able to replicate the sudden powerdraw issue when placing fuel tanks.