fabricating your own fuel bladder?

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Will Aldridge

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I'm working on the design of the fuel system for my plane and have been told several times that fuel bladders are the way to go and the one site that keeps coming up is this one: http://http://www.atlinc.com/uavbladder.html
And I keep wondering about the possibility of fabricating my own? I have tried the search function here but haven't come up with anything useful. So is it doable? Are the raw materials available for sale? Are the fabrication techniques within the reach of the average Joe with a minimum outlay of cash for tooling? Any other major gotchas to be aware of?
 

TFF

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I dont think you can make them at home. Not for talent. I dont think you can source the materials and buy the equipment in any reasonable homebuilders way. You probably have to start at the MIL spec and get materials made. Proprietary is going to be what you would be fighting. I cant see you doing it for less than getting it done at ATL or some other place; probably on the factor of five.
 

Hot Wings

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I remember watching a video a few years ago where one of the big name fuel cell manufacturers built a custom bladder for a college teams fuel mileage project car for one of those engineering type competitions. I couldn't find it last time this subject came up or I'd post a link.

From what they showed in the video this is most definitely something that we home builders could probably do with not too much trouble. It would take some experimenting and testing, but isn't that part of what we already do?

Short version of the process:

Lay out the material, kevlar/glass.
Work in by hand the binder which looked like nothing more than ProSeal. This was done with a process very similar to the way we make sheets of homemade prepeg.
Let cure.
Cut out the needed parts using cardboard templates.
Glue the bits together with what looked like some more Proseal.
Attach fittings and stuff in container.

McMaster Carr last I looked, was a source of some ready made materials. Another source might be the urethane material used to make inflatable boats.
 

Eagle

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Personally I would try to avoid the use of any kind of rubber anywhere in a fuel system. For all the trouble making
a bladder, why do you feel it would be any better than a trouble free stainless tank. You never have to worry about
the rubber deteriorating. I helped install a bladder in a Cessna several years back. Lot of work and expense. The
biggest concern I have is that you never know what may be mixed with your fuel today or in the future.

I'm getting ready to order some fittings and fuel line and while looking through the catalog of a major manufacturer
for these items, I read a warning that they could not guarantee that even their best rubber lined hose would not
succumb to unknown additives that petroleum companies may place in their fuel.
 

Jay Kempf

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Why wouldn't you be able to cut and heat seal material? I just don't see the massive tooling required. I suppose you could also bond. The fabrics are available completely finished from several industries. Match the fabric to the fuel and cut and seal the bag. Then design a fuel in and vent flange/cap and you have a bladder. This is something that I always wanted to do for my own purposes. I looked into bag storage for solar water over the last few years. I had this idea to do a dual bladder for inverted fuel where you have one bladder with air pressure that collapses the inner bladder with fuel in it. Sort of like an accumulator in a water system.
 

Jay Kempf

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Personally I would try to avoid the use of any kind of rubber anywhere in a fuel system. For all the trouble making
a bladder, why do you feel it would be any better than a trouble free stainless tank. You never have to worry about
the rubber deteriorating. I helped install a bladder in a Cessna several years back. Lot of work and expense. The
biggest concern I have is that you never know what may be mixed with your fuel today or in the future.

I'm getting ready to order some fittings and fuel line and while looking through the catalog of a major manufacturer
for these items, I read a warning that they could not guarantee that even their best rubber lined hose would not
succumb to unknown additives that petroleum companies may place in their fuel.
Aren't all Cessnas fueled with bladders in the wings?
 

TFF

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Most aviation cells seem to be vulcanized nitrile rubber internally with a abrasion resistant outside bonded to it. Essentially sheets of o-ring material.
 
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