KSP fuel glitch? And guess I have a new Mun base.

[Elfmaze]

Five identical tanks, Five identical engines. no thrust limiters, Full tanks on liftoff, and no means of transferring fuel. And yet when going to land I kept having a nasty spin start up near the Mun surface. Upon research I found that All the tanks were burning at different rates and one nacelle runs out of fuel about 2000m up.

SO after some re-balancing and shuffling engines on and off during the de-orbit burn I was able to get it on the ground at least.

I went to review my fuel situation as far as returning to Kerbin..... Yeah, probably not going to happen. One tank is not even reporting, and another tank is 100% full still?

I have a ton of science on this one. As I understand if I transmit the data i get a portion and then I get the rest if I ever recover the craft?

- - - Updated - - -

I will try blasting off with just the two outer engines and a little push from the center. I'm thinking eva and gather the data(might be tough as they are tucked into service bays). and hopefully bring the pods and two pilots home

[Elfmaze]

there was something wrong for sure. I even checked the thrust limiters and all were 100% but as I tried to blast off it spun more even with the three engines. (weight difference between sides?) and the engine with 100% fuel read ~10% on the stage fuel gauge..... RIP Bill and Matt

[LordFerret]

I have just run into a similar problem, starting right at the launch pad. I'll be posting about it after writing this. :/

[PlonioFludrasco]

Girders are fuel crossfeed capable. Probably fuel is drained through them.

[Elfmaze]

Girders are fuel crossfeed capable. Probably fuel is drained through them.

Is crossfeed fueling an upgrade? I though I might be able to transfer but didn't figure a way to do it.... I'll check out some you tubes on it.

[Vectura]

I think they meant more along the lines of that 1 tank was being drained by all 4 engines because they could all draw fuel from it.

[Snark]

By the way, about recovering the science:

It's true that you get a fraction if you transmit... but then the science is gone from that craft and you'll get nothing for recovering the craft afterwards (unless the craft can take the measurements again).

So don't transmit unless you are OK with that.

Another option for recovering the science is to land another craft next to it, use a kerbal to manually transfer the science across, and then retrieve that other craft. Gets you 100% of the science.

[Old Foxboy]

I have this BUG too, once in a while. Fuel is drained asymmetrically from twin stacks of attached fuel tanks or constructions on lateral separators or things like that. In a weird way, the program prioritizes some fuel tanks over others, draining some and leaving the rest. This might lead to a premature shutdown of engines that are attached to the drained tanks, because they obviously can't get fuel from the rest of the ship while the other engines can drain this tank. Not fuel pipes attached, but there are some one-way fuel flowing mechanisms that definitely shouldn't be there.

[bakanando]

Although I don't know what could have affected the fuel this way, there's a way to fix the fuel levels. You will need to upgrade your R&D building for fuel transfer capabilities though.

You seem to have just enough fuel for two full tanks plus a bit in another, thus:

1. Fill both tanks below the pods.

2. Transfer the remaining fuel to the center tank.

3. From both full tanks, transfer fuel to one of the empty radial tanks until it fills completely. You'll now have two tanks half full, one full, and one empty. Plus the central one.

4. From the full one, transfer half the fuel to the empty radial one. This might not be perfect, but at least you'll have just a slight fuel unbalance in one direction.

5. Transfer fuel from all the radial ones into the central one until all are level or the central has as much fuel as you want. You can even fill it if you want.

There are better ways, but this was the easiest I found that could be made quickly.

And for you problem, try disabling any and all mods that you are using before lifting off again. One of them might be causing the problem.

For further troubleshooting a craft file or more pictures can help.

[Rhomphaia]

From the numbers, the two tanks with material bays are draining the samewhile the tanks with the command pods are draining differently.

Assuming that the root part of this vessel is on the center stack, then Raidial fuel flow rules Should mean that all of outer tanks can drain from the central tank which should burn out first. before each engine starts to drain its own tank because of the girders.

However if this vessel was decoupled from something else then then One of the command pods may have become the root, and something odd may have happened to the parent child relationships between the tanks causing the wiedness

Just my guess anyway

[Geschosskopf]

However if this vessel was decoupled from something else then then One of the command pods may have become the root, and something odd may have happened to the parent child relationships between the tanks causing the wiedness

Just my guess anyway

That would be my guess as well. Having multiple command pods off-center can make all sorts of weird things happen, so is best avoided.

[MarvinKitFox]

You don't have five tanks there,

you only have one 5-part tank.

Using girders between two fuel holders does not separate them, it is just one fuel holder in two blobs.

Add a decoupler on the center mounting, even if you never plan to decouple it. That will isolate the fuel.

[Elfmaze]

craft file, first time I've loaded one so apologies if i did it wrong

https://www.dropbox.com/s/ucrbtesktooz8hd/MUN%20LANDER%20%202_3.craft?dl=0

I had to build it off-center to accommodate the Launch escape system for a contract. (weight balance and all) I think building it off center is what screwes with the game. When I test fire the four outer lander engines at the pad it still burns oddly.

[Alshain]

The issue is that when using rocket engines, it starts at the engine and moves in reverse through the connected parts until it finds the first part in the tree with fuel and drains that first. Just because your rocket isn't built straight up and down, doesn't mean that isn't how it is in the save file. It will still progress through the tree of parts and find the first one with fuel and proceed to drain from there.

It is a bit complicated, but in the craft file/persistence file, everything starts from the root and moves linearly in a tree fashion. When you build outward, the tree may get harder to follow. DasValdez explains this concept very well.

Edited May 19, 2015 by Alshain