RC Gas engine plumbing systems

[shad]

Made an account just for this question. I've been searching online for gasoline compatible fuel bladder solutions. I've come across builders using plastic bags with the proper brass fuel tank fittings, but I have no clue of the container being used. Examples:

 

[fstnd]

RC planes use fuel tanks which are essentially bottles with holes in their cap where fuel lines can flow through

 

[shad]

Someone replied to me on another forum recommending the Zippkits brand:

https://zippkits.com/index.php?main_page=index&cPath=93

Which is a cheap fuel bag solution (though I haven't tested their product myself).

example product:

 

[HPIguy]

Why do you want a bag/bladder specifically, rather than a fuel tank?

 

[shad]

For a variety of reasons. Personally, I feel it simplifies RC plumbing systems:



- No vent line is needed as the volume of the container changes as it's emptied. Which also prevents leaking as the fuel system can now be fully enclosed.



- Consistent fuel mixture: Ideally, with little to no air in the fuel bladder (vacuum impossible), there is very little sloshing, mixing the air and fuel. This makes the flight performance more consistent when compared to rigid tank systems.



- Form: The bladder can fill irregular volumes (more important for aircraft).

I could be wrong.

 

[tudordewolf]

The issue with fuel cells is longevity - from the website linked by @fstnd

"These top quality bags have a useful life of about 1 year.
After that, they start getting hard."

You'd have to re-do your fuel system annually. There's not many plastics that are both flexible and fuel resistant, not for long anyway.

Other options are a header tank, nitro helicopters use them and that's just about the most stress you can put on a fuel system.

It's a smaller tank between the main tank and the carb with the opposite of a clunk, the pickup is stiffly held in the center of the tank and you purge it before flight, so it traps any air bubble that make it through from the main tank. By the time it starts burping air through, the main tank will be empty.