Spaceplane Fuel Flow issues

[lyndonguitar]

Hi, I recently been trying to make a spaceplane. The fuel consumption starts with the front tanks, then going to the back.

My problem is that when the front tanks get depleted, My plane would topple and will lose control. So I need to make the fuel flow reverse. the back tanks must get depleted first then the last one to get depleted will be the frontmost one. Basically reversing the whole fuel flow.

I tried fuel lines but It still uses the front tank first.

I tried disabling them one by one manually during flight, it worked, but It's a hassle

Edited May 25, 2013 by lyndonguitar

[HoY]

Fuel lines are your answer. Do you have tanks beside the center fuselage? Or just the one stack of tanks?

[lyndonguitar]

Fuel lines are your answer. Do you have tanks beside the center fuselage? Or just the one stack of tanks?

One stack of tanks only. here's a layout of the plane horizontally(sorry to lazy to screenshot)

(Cockpit)(Tank1)(Tank2)(Tank3)(Tank4)(Engine)

It uses Tank1 first, after depleting it, my design will make it topple, however i'm 100% sure that my design won't topple if Tank4 would be used first. I tried using the yellow thing fuel lines, it still doesn't work. probably the built-in fuel crossfeed between the tanks are messing them up.

[Dictator Dan]

Try cockpit, tank 1, tank 2, tank 3, tank 4, something with no fuel cross feed, engine.

Run a fuel line from tank 4 to tank 3; tank 3 to tank 2; tank 2 to tank 1; then tank 1 to the engine.

[lyndonguitar]

Try cockpit, tank 1, tank 2, tank 3, tank 4, something with no fuel cross feed, engine.

Run a fuel line from tank 4 to tank 3; tank 3 to tank 2; tank 2 to tank 1; then tank 1 to the engine.

I did what you said, It still uses the first tank.

[Dictator Dan]

(10 characters to post)

[Melfice]

Download the TAC Fuel Balancer mod.

That'll sort you out, no worries.

I'd link you to Spaceport, but it's down. It should be in the Plug-in add-on section though.

[rodion_herrera]

I have the exact same problem that lyndonguitar has...but I want to do it without mods. Any other suggestions?

-RODION

[lyndonguitar]

Download the TAC Fuel Balancer mod.

That'll sort you out, no worries.

I'd link you to Spaceport, but it's down. It should be in the Plug-in add-on section though.

Thanks, unfortunately, the thread also links to the spaceport page, lmao, I guess I have to wait for the maintenance then

EDIT: anyone here kind enough to upload the mod for me?

@rodion_herrera

It's nice to see another countryman here

Edited May 22, 2013 by lyndonguitar

[rodion_herrera]

@rodion_herrera

It's nice to see another countryman here

Likewise

-RODION

[georgTF]

If the problem is the front of the plane getting lighter as fuel is burned, the solution may be to use structural parts to extend the rear of the plane and add some wings there. Usually the heaviest section of a plane that is low on fuel (and this is the case when returning/landing) is the engines, esp. if you use many engines. The solution is to redistribute the lift surfaces to cope with the weight of a "dry" plane. It's better to have a plane that can land easily but struggles to achieve orbit, than to have a plane that orbits easily but is hopeless when flying "dry".

A possibility is using tanks arranged side by side rather than in-line. That way the CoM shift is less pronounced because most of the mass stays in the same place. Here are the only two succesfull designs (out of 40+) that i can consistently orbit and land. They both have most of the weight towards the rear and the smaller one has wings behind the engines. That made the biggest difference for me.

In general there should be just enough lift to take off even if you have to fly off the runway to do it, otherwise the plane will kick like a mule once it's empty. Again, i'm happier once i can actually land the plane easily and only need to figure out how (much to airhog) to achieve orbit. Spaceplanes are very frustrating, and very hit-and-miss. Good luck. They're worth it though.

[HoY]

It's doable stock. Behind your rear tank install a single flat steel plate, and install your engine on the back of that. Now run a fuel line (or two for symmetry) down the length of the fuse from the front tank to the engine.

That's the way to do it with the least amount of extra parts. You can install fuel lines between each tank tucked inside with the fuel flowing forward then have the foremost tank piped to the engine directly as well but that's slightly more complicated.

[rodion_herrera]

It's doable stock. Behind your rear tank install a single flat steel plate, and install your engine on the back of that. Now run a fuel line (or two for symmetry) down the length of the fuse from the front tank to the engine.

That's the way to do it with the least amount of extra parts. You can install fuel lines between each tank tucked inside with the fuel flowing forward then have the foremost tank piped to the engine directly as well but that's slightly more complicated.

Oh so the point is not to allow direct feed? The flat plate acts as barrier?

-RODION

[rodion_herrera]

Spaceplanes are very frustrating, and very hit-and-miss.

Well right now, with ANY SSTO spaceplane (of SOUND design), I can guarantee that I can reach orbit--my notes on the how-to remove any "misses" that might be an issue. The re-entry and re-introduction to atmospheric flight is what's really messing my efforts at the moment, and it's mainly due to CoG+lift issues re design. If I can get that down pat, all aspects of SSTO spaceplane is now doable and easy from my PoV.

-RODION

[HoY]

Yep it's not cross feed enabled. It's how I run the center jet on my Firebat VTOL ssto

Not a great shot, but see the center engine mounted under the FLT800 tank? Didn't want it to use fuel from that so it's isolated by a plate and fed fuel from the 4 jet fuel tanks.

As I mentioned with the second method, if you use fuel lines between every single tank directing the fuel forward then from the foremost tank to the engine, you can achieve the same effect. It DOES create a fuel loop however because the tanks are in line it doesn't unbalance the craft. Method one is more reliable.

[rodion_herrera]

Thanks, will give it a try.

-RODION

[lyndonguitar]

Anyone here has a copy of the plugin TAC fuel rebalancer? can someone share to me please?

[Melfice]

I have the exact same problem that lyndonguitar has...but I want to do it without mods. Any other suggestions?

-RODION

While that's an admirable attitude, I do suggest you try out some mods. There are some amazing, well-balanced mods out there.

If you really don't want to, fair enough.

Anyone here has a copy of the plugin TAC fuel rebalancer? can someone share to me please?

I have no idea how TaranisElsu feels about other people uploading their mod, so I think the best bet is to wait for Spaceport to come back online. I doubt it'll take very long.

[HoY]

I doubt it'll take very long.

Famous last words.....

[Melfice]

Relatively speaking then.

[rodion_herrera]

While that's an admirable attitude, I do suggest you try out some mods. There are some amazing, well-balanced mods out there.

If you really don't want to, fair enough.

I have about seven folders of KSPs installed on my system. Each has its own KSP.EXE and folder structure and has a specific purpose, i.e. one folder is named KSP_aero, which basically contains mods that have anything to do with aerodynamics and in-atmosphere operations, another folder is named KSP_robotics, which of course contains mods that have anything to do with robots, and so on and so forth, also a KSP_purestock, and KSP_backup...etc. etc. So yes, I do like mods--I just don't like the fact that the game loads excruciatingly long if you have them all in one directory. Which is why for a simple test (stock is good for tests--it creates a benchmark) like an SSTO Spaceplane, I like to use my KSP_purestock folder for it. And thus my question.

-RODION

[Innuce]

Try running a fuel line from tank 1 to tank 2; tank 2 to tank 3; tank 3 to tank 4; then tank 4 back to tank 1.

Effectively, all the tanks should drain evenly, so your craft's overall balance isn't affected.

[Melfice]

Ah, well.

With the "I DON'T USE MODS BECAUSE IT'S CHEATING" folks that like to run around occasionally (mind you, it's been rather quiet on that front for a while now, I think?), that would have been info useful to know.

Still, I should have worded that differently, and maybe not jump to that particular conclusion.

Are we still friends?

And with friends, I obviously mean "two people who don't even know each other, aside from a brief interaction on forums".

[MR4Y]

Try cockpit, tank 1, tank 2, tank 3, tank 4, something with no fuel cross feed, engine.

Run a fuel line from tank 4 to tank 3; tank 3 to tank 2; tank 2 to tank 1; then tank 1 to the engine.

Something with no fuel crossfeed... Does it exist? Pretty much every single stock part of KSP, including even structural parts, can do fuel crossfeed.

[Payload]

Something with no fuel crossfeed... Does it exist? Pretty much every single stock part of KSP, including even structural parts, can do fuel crossfeed.

Decouplers and the grey flat plank things don't cross-feed fuel. FWI. I tend to use a decouplers to isolate engines from tanks so that I can route the fuel how I see fit.