Fuel cross feed hell

[Guest]

Hi guys I am having a problem. I am restricting myself to no mods at the moment. I worked on a medium sized SSTO for over two days off and on, and was finally happy with it. But it took all that time. Tonight in 20 minutes I slapped together a good looking and good performing fighter like SSTO which is a revision of a previous design. I cut the engine count from 4 to three, but in that process the fuel simply will not feed evenly from the left and right, to the rocket. Jet feed is fine, they're burning from the three tanks evenly. Good to know: If I remove all the yellow fuel lines, no engines get fuel, even though those two to one adapters the engines are mounted with claim to be crossfeed capable. At the moment I have given up and may use TAC fuel balancer.

The pictures depict the three tank statuses while idling the rocket engine only.

[Giggleplex777]

Have you tried putting a structural panel before the bi-couplers? That stops the cross-feed.

[Guest]

My small brain cannot figure out what you're saying.

I have made a discovery. Bi-couplers will only feed fuel one way. They will feed from the one side to the two side. They will not feed from the two side to the one side. I just did a simple test. This is a big part of the answer to my problem I believe. Investigating.

[Giggleplex777]

That's because the center engine is only connected to one of the tanks.

[Guest]

It's acting totally unpredictably. Just now I have removed the inverted bi-coupler - the one I place first, to attach the rocket to the two tube sections. Using parts clipping ON, I have placed two bi-couplers on the two tube assemblies, to get two places for the engines, plus a third in the center, where the couplers overlap, for the rocket. I placed a 1 x 1 metal panel there, and as you said, all fuel flow is indeed blocked. I tried with and without and the plate IS blocking fuel. I thought I was on my way to a workaround. I placed two fuel lines directly from both the left and right 'main' tanks, to the rocket itself. Now, its burning fuel AND oxidizer from the right 'main' tank, oxidizer ONLY from the left tank, and fuel from the adapter up front.

I think parts clipping and the bi-couplers are going crazy - I think there's something in the code that is malfunctioning.

I am going to try to disconnect the front tank and see what happens.

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After disconnecting the front tank, the rocket will burn fuel and oxidizer evenly from the left and right tanks!

Edited September 6, 2013 by Guest

[Guest]

The left tank somehow out of my control, thinks the front tank is a part of it, no matter how the front tank is connected to any engine. I just triied ducting fuel directly from the front tank directly and only to the jet engines, and the rocket still burns from it.

[Guest]

I have an inverted bicoupler up front, right behind the Mark I to Mark II adapter which is the front tank. The fact that it is inverted could be a part of the problem, and allowing fuel flow in unexpected ways.

[Guest]

Nope. It's mocking me. Done for the night.

[KerbMav]

Can you take a screenshot in the SPH of the parts you used at the back of the plane? Just pull them of the craft and let them "float" behind it.

What is that part (left side of your pics) behind your cockpit with the first fuel lines?

But I see two possible problems:

1. Why are you cross-/x-feeding fuel from left to right and then right to left again?

2. the 2-to-2 adapter is - fur sure - only connected to one fuel tank, you cannot build a "loop" in KSP (while in the construction buildings at least).

Honestly I am not even sure I understand how you magicked that part onto your craft ... *tilts head*crosses eyes* ... no, cannot tell ... is it even a part I know??

[Guest]

I fixed the problem - I can still show pix if you want. I still do not fully understand how fuel was flowing and how it was not flowing. The solution was to isolate the rocket by placing a 1 x 1 steel plate between it and it's mounting surface. Then I have two fuel lines feeding it one from each tank.

The ship uses a mess of 2-1 adapters and they seem to be real quirky with regard to fuel flow.. "Fuel loop" - extremely interesting and likely part of the problem.

I am real close to uploading to Spaceport may happen tonight.

The ship is 100% stock, you might be looking at three 2-1 adapters one being flipped upside down.

Edited September 6, 2013 by Guest

[Guest]

I am gonna cut the words to a minimum. This is where I am at, and I think I am done. I like it. The problems I was creating with backwards overlapping 2 to 1 bi-couplers was quite amazing.