Fuel flow order

[rpayne88]

Here is my best attempt so far at an SSTO.

I am trying to get it to drain the two drop tanks underneath first (guess it doesn't technically qualify as an SSTO, but it is reusable,) then drain the two tanks in the nose, then the pair of FTL-800s hidden by the vertical stabilizer, then the front most FTL-800s, then the ones in the middle. Finally, I want it to drain the Mk. 3 rocket fuel tank in the fuselage for all three engines to burn out at the same time. I have TAC fuel balancer; is there any way I could do this other than manually disabling the fuel flow from each tank and re-enabling it in-flight?

[Cashen]

Not sure if this answers your question, but fuel flow using the stock fuel lines always flows from the tank furthest away, as in, the most number of fuel lines away. So a good way to do it is to start running fuel lines from the first tank you want to drain, backwards in order towards the last tanks you want to drain, which should be connected directly to your engines (or the engines themselves if they aren't connected directly to fuel tanks). It's therefore best to design the layout of your fuel tanks to make this path as simple as possible.

That's a friggin' huge SSTO by the way. You can make an SSTO spaceplane much smaller and simpler than that (of course it will have less of a payload, so it depends on what you want to use it for). Your TWR numbers are all below 1 so that worries me as well.

Edited July 17, 2013 by Cashen

[K^2]

I wrote a tutorial before the big crash. It has now gone the way of the dodo.

Basically, think of fuel drain order as fulfilling a request. Here is the loose algorithm.

1) Part is asked for fuel.

2) Are there any fuel lines to the part? If so, ask the connected parts for fuel. If more than one respond, fuel is split equally.

3) If no fuel came in from fuel lines (or no fuel lines) ask any parts directly connected to this one for fuel. If more than one is connected, same drill, split the fuel.

4) If no fuel came from connected parts either, fulfill request from this part.

5) If you got to this point and there is no fuel in the part either, then the request is not fulfilled.

Naturally, you start this chain of requests from the engine and any part that's been already requested fuel from will not be requested a second time. So naturally, requests are fulfilled from furthest tank from the engine, with fuel lines given priority over direct connections.

So in order for drop tanks to deplete first, you need a fuel line that runs from drop tanks to the tanks that currently deplete first.

P.S. Your TWR is a bit low. Even with a space plane you generally want something over 1.0. Preferably, something closer to 2.0.

Edited July 17, 2013 by K^2