Does CoM matter in vacuum?

[FrontierProject]

in context, I launched the KWRocketry [iforgetwhichrocket] W/ NTR Stage, I'm planning on a Duna or Eve mission with it, but I noticed the side-straddled tanks don't have fuel lines, so the only way to use them would be inflight transfer. Now although it would be possible, it would be annoying and time consuming to try and balance 2 different fuel types (liquid and oxy) in 4 different tanks, so I'm wondering if there would be balancing issues if I simply emptied one tank at a time into the engines' tank.

I considered adding the fuel lines myself, but iirc if u have 4 tanks emptying into a single main tank the game will just empty them one at a time anyway.

Edited June 26, 2013 by FrontierProject

[maackey]

Yes, CoM does matter in vacuum. Manually balancing fuel is only for the insane and masochistic; I would suggest adding the fuel lines yourself.

Fuel lines going radially in to a main stack will drain evenly. Fuel lines going radially out from the main stack also drain evenly. This is assuming your radial tanks/stacks are all the same size, I haven't really tried it with uneven sized tanks. Its also good to put them on the lowest tanks as fuel is drained from the highest tanks first.

[FrontierProject]

Kk thanx.

*random garbage to get character count over 10: 8908(&*(^&

[falofonos]

You only need to keep the center of mass inline with the thrust vector, so if your main tank can take the contents of 2 of the side tanks then there's no need to balance really, just move 2 opposing tanks worth into the main tank once it is empty.

It is so much easier to use fuel pipes though.

[Eric S]

I considered adding the fuel lines myself, but iirc if u have 4 tanks emptying into a single main tank the game will just empty them one at a time anyway.

That may be true in some specific case, but it's not generally true. If you have four tanks that are in separate radially mounted stacks and connect a fuel line from each of them to one central fuel tank, the game's fuel flow logic will take fuel equally from all four tanks.

If, on the other hand, you have four tanks arranged in two stacks (two tanks per stack), then even with all four tanks having fuel lines, it will drain two of the tanks first, then the other two. In fact, if you have tanks stacked on top of each other, there's no reason that I'm aware of to run individual fuel lines for each tank.

[FrontierProject]

I checked and the tanks are radial, so my updated version with a human command pod will be carrying fuel lines.