Fuel flow problem

[kBob]

I found some help about the rules of fuel flow but I don't think that's my problem.

Here's a diagram of my fuel engine stack:

| --t800 #0

| --t800 #1

| --t800 #2

|=| --t800 #3 radially connected to t800 # 4 and has a pipe flowing from 3 to 4

^ ^ --the two engine connected at the bottom of the stack.

Some of these work fine fuel is used from them all.

But some do this: fuel in #4 and #3 is used up and then flame out while tanks 0, 1 and 2 stay full.

Any ideas?

[I_Killed_Jeb]

Are you sure the ship didn't undergo a breakage when the fuel flow doesn't work? Use F3 to bring up the flight log and verify that isn't the case

[Taki117]

I think a picture would really help here, but it sounds like you are running your line from your center stack to your radial stack, try running it the other way around. This will result in Onion Staging.

[kBob]

No breakage (will not until the ship runs out of power too soon).

The stacks are independent.

The one on the left works the one on the right...with winglet doesn't. Hmmm. now that I think about it the other two that don't work also have winglets maybe it's interfering with the fuel scan process?

I'll try removing them (need 'em though).

Edited February 2, 2014 by kBob

[kBob]

Wasn't the winglets. Still the same problem most of the stacks work fine but three of them only drain fuel from the two bottom tanks.

If I ran the line the other way I'd only have one tank's worth of fuel (the lines are unidirectional according to the info).

Funny this thing was rotating around the horizontal axis a bit so I added the winglets which stopped it, but now with them gone it's still stable (though I haven't tried to turn it). What you see here is just the second stage once I get it working right (and even on bad fuel it goes to 7km) I'll add the third stage.

[Claw]

Assuming you've already checked the pipes for proper placement and direction...

Sometimes I've had parts connect in the wrong locations or not register. I would be especially suspicious of this if your three tanks that do this happen to be all placed simultaneously with the symmetry tool. Pull them off and put them back on to see if that fixes it.

The other thing you can check is that you didn't inadvertently turn off fuel feed via tweakables. Right click on the tanks that don't feed and check that you have two little green arrows, instead of red "no" icons.

[Taki117]

What exactly are you trying to do with this? It looks way over engineered.

[kBob]

Alas they are all green. I thought about the symmetry thing pretty sure those are ones placed using it. I have things so tight not to mention all those struts to replace (I like rigid structures) that I'm having a hard time placing things (I'm new at this I'm sure I haven't found all the tricks yet) so I was hoping to avoid having to redo a bunch of stuff...hope it works.

First thing is a trip to the sun (it will pick up the science there) then I was wondering if I could do a sort of grand tour of the inner system, mostly I want to carry enough fuel to go places and do things...it's really a learning tool. I know all those struts look like over kill, but I got tired of things breaking apart and all those triangles make for very rigid reliable ships...it's an overgrown version of my last ship which held up on my Mun trip quite nicely with no problems despite the abuse I gave it, I plan to add a lander to this once (if) the design is proven (biggest problem no is ejection trying to figure out best placement for sepratrons). Besides, bigger is funner that's why I learned to fly 747's in flight simulator back in the day.

What I guess I need is docking ports so I can assemble things in orbit but for now it all goes up at once (pun intended).

[Claw]

Instead of pulling things off to see if that's the problem, try connecting a fuel line from the unfeeding tank to the tank it should be going to. (Connect tank 2 to tank 3, I think by your schematic.) That might tell you where the problem is, but you can still use your design.

[Pecan]

Look carefully at the tank at the bottom of your stack-with-winglet. It does not align properly with the one above it. Symmetry - or whatever - has not attached those tanks to each other, which is why the fuel doesn't flow. As Claw says, you can correct it by adding a fuel line yourself.

[kBob]

Well I seem to have hit some kind of bug. I was able to connect fuel lines between tanks 2 and 3 and this allowed tank 2 to drain but tanks 0 and 1 remain full. So I rebuild the stacks, this worked for two of them they drained properly top down...without any extra fuel lines. But the third stack well I tried three times but tanks 0 and 1 would never drain and on the third time the other two stacks started doing this too even though I hadn't touched them! This is with symmetry off. So I said to heck with it I'll just connect fuel lines between all the tanks...but it won't let me I can connect a fuel line between tanks 2 and 3 but not between 1 and 2 or 0 and 1.

One good think I've got the hang of connecting things, but even though they look connected and solid something is not registering. My part count is in 300 range maybe that's too much? But really I'm thinking it's some kind of parsing error in how fuel flow between parts is calculated.

I'm going to try rebuilding the stack one more time this time with 3 way symmetry. Otherwise maybe I'll try the support forum or give up for a version or two see if it gets better with new releases.

[kBob]

Well I give up. The stacks rebuilt with symmetry worked fine, but stacks that had been working and weren't touched started failing and when I reverted to the assembly they disappeared, rebuilt them back to launch and their engines fell off (I made no changes just replaced them including same struts) replaced them and the fuel problem was still there and they again fell off at launch didn't happen before something is screwy with the connection system. Maybe they are too close together, but I look at other designs and people don't seem to have this problem.

[kBob]

I made a much smaller version with stacks of 3 fuel canisters that works fine though I didn't feed two engines off any of them (but some of the 4 stacks that had one engine stopped working) maybe I reached some limit on the total number of fuel tanks one ship can handle? Probably become moot as I work my way up the tech tree and get more efficient engines (and well non-liquid engines).

Anyway thanks for the ideas.

[MarvinKitFox]

One simple rule when building and joining tall rocket stacks to tall side stacks.

Build your extra stack vertically below your craft centerline to ensure the assembly puts all the parts in the right sequence, *then* detach it and place it on the side mount where you want it.

Never build a side expansion off a decoupler, and then add more bits to it. That is asking the program to break your design.

[Kasuha]

One simple rule when building and joining tall rocket stacks to tall side stacks.

Build your extra stack vertically below your craft centerline to ensure the assembly puts all the parts in the right sequence, *then* detach it and place it on the side mount where you want it.

Never build a side expansion off a decoupler, and then add more bits to it. That is asking the program to break your design.

Strange, I do that all the time and I stil did not meet this kind of error. Instead, I am getting some nasty errors if I build the stack in the middle, apply something in symmetry to it, and then attach the stack itself in symmetry somewhere.

My rule is: when the ship structure breaks it can't be fixed and you need to rebuild it from scratch or from last unbroken save. Sometimes saving and reloading the ship in the middle of construction helps build correctly what'd break otherwise.

[kBob]

I think you're both on to what was happening. I'm still a bit new to this and sometimes I miss-click and pick a wrong part and have to put it back and maybe that's when the problems were introduced. Somehow I didn't think the order in which it was assembled was all that important seems like the ship parts should be parsed after leaving the hanger or during a save, but I guess not.

In my latest design if I goof a stack or something I go back and start it over. I also suspect the symmetry tool is complicating the issue. At least I'm getting better at connection the parts though it is still stubborn at times. Now I've got a good trainer that lets me practice changing orbits and should be land on Mun and Minmass multiple times and still return and pick up lots of science. Instead of those tall four stacks I've been doing three stacks and radially attaching a fourth tank which can be decoupled once empty.

Thanks for the help...I'm learning.

Kasuha--I have your thread about fuel flow rules bookmarked very interesting.

Edited February 3, 2014 by kBob

[Kasuha]

sometimes I miss-click and pick a wrong part and have to put it back

That IMO happens to everyone. If your ship is reasonably sized (i.e. it's not made of thousands of parts), the safest way to get it back is to hit the Delete key to get rid of the part you just picked up, then press Ctrl+Z and wait till the ship returns to previous state.

[kBob]

Sounds good, I've been using del and crtl-z more often but I'll make it policy, just got to convince my fingers to go along. I have to use a very small mouse due to arthritis and so I suspect I may be mis-clicking more often than average...or maybe not . Just when I think I'm getting the hang of building things something weird happens and I end up going backwards instead. I've also learned to test very frequently and save several versions as I'm building. These forums have been invaluable too thanks for the tips.