Balsa Fuel Tank?

Levent Suberk Thu Dec 03, 2020 12:02 pm

I want to make a one ounce two line operation fuel tank from balsa sheet, fuel proofed with epoxy. Have you any recommendations about this?

davidll1984 Thu Dec 03, 2020 12:44 pm

Not sur wit long terme storage tink its posible option y just use baloon if impossible To use tank seal internal wil be hard To use exact layer of epoxy on complète surfaces it can crack after hard landing leak on rest of the plane is may be a way of saving weight wit balsa Not sur Huh...

fredvon4 Thu Dec 03, 2020 1:08 pm

Roll or carve the wood...any wood to the volume you expect yields what you desire. I personally would use fast cure epoxy as it seems to be most pliable after cured and it certainly is fuel proof

Find and use Copper tubing...brass cracks and corrodes to green crap over time

there are dozens of ways to skin the small fuel tank need..I have become very fond of the simple non pressurized balloon versions

KariFS Thu Dec 03, 2020 2:40 pm

Very novel idea! You will need to get the balsa impregnated with epoxy, and that might be easiest to do while the tank is not assembled yet. Slow epoxy, thinned with ethanol and/or heated, maybe some vacuum assist... After that, cut and glue the sheets to make the tank. And then, re-seal from inside and out.

Or are you going to carve the tank from a block?

If you need an odd or complex shape, 3D print might be the way?

sosam117 Thu Dec 03, 2020 2:54 pm

I miss the old 35mm film canisters.

1st when they were made of aluminum.

Then out of plastic.

They made great (cheap) fuel tanks for 1/2A (Cox) engines.

dirk gently Thu Dec 03, 2020 3:15 pm

I still use them today. I have several vintage cameras to use the film, but if you've switched to digital photography completely, I bet you can get the canisters fir free anywhere film is developed.

Levent Suberk Thu Dec 03, 2020 3:37 pm

KariFS wrote:Very novel idea! You will need to get the balsa impregnated with epoxy, and that might be easiest to do while the tank is not assembled yet. Slow epoxy, thinned with ethanol and/or heated, maybe some vacuum assist... After that, cut and glue the sheets to make the tank. And then, re-seal from inside and out.

Or are you going to carve the tank from a block?

If you need an odd or complex shape, 3D print might be the way?

Exactly in that way. I want to build it from balsa sheets. First I cut all balsa parts of fuel tank. I place a strip of double sided tape on opening of a nylon bag. Then I place a silicone fuel tubing inside of bag and I fill the nylon bag with thinned epoxy. I close the bag and vacuum with a large syringe. The parts absorb the thinned epoxy. Then assembly with epoxy and aluminum tubing is easy.

I simply want to build a balsa tank as a novelty. Very Happy

Levent Suberk Thu Dec 03, 2020 3:41 pm

sosam117 wrote:I miss the old 35mm film canisters.

1st when they were made of aluminum.

Then out of plastic.

They made great (cheap) fuel tanks for 1/2A (Cox) engines.

Thanks for this, but I can't epoxy aluminum fuel tubings on lid of plastic canisters. Those lids don't hold epoxy, as like as most plastics. But metal canister is allright for the job. I had one metal film canister, Kodak brand, but lose it.

Levent Suberk Thu Dec 03, 2020 3:45 pm

fredvon4 wrote:Roll or carve the wood...any wood to the volume you expect yields what you desire. I personally would use fast cure epoxy as it seems to be most pliable after cured and it certainly is fuel proof

Find and use Copper tubing...brass cracks and corrodes to green crap over time

there are dozens of ways to skin the small fuel tank need..I have become very fond of the simple non pressurized balloon versions

Thanks Fred, I didn't know that brass tubing corrodes within time in fuel.

NEW222 Thu Dec 03, 2020 6:36 pm

Wow, those early 35mm camera film holders are quite neat. I had never known they came like that.

germanbuddy Thu Dec 03, 2020 9:19 pm

....I didn't know that brass tubing corrodes within time in fuel..

Same for metal glowfuel tanks made of brass sheet.
5 years ago watched this at my CL buddy Peter P. .
After month break he fueled his OS FP.40 Profile Stunter´s brass fuel tank.
Seconds later , black muddy goo blocked his fuel filter after
the tank cracked open along 90 degrees sidewall bend.
The tank was black coroded badly from inside with black slime.
Brass and Glowfuel is not the best combo ,never was .
Brass may work with Diesel fuel but not for Nitro-Glow in the loooogrun.

Buddy

dirk gently Fri Dec 04, 2020 3:17 am

Levent Suberk wrote:
Thanks for this, but I can't epoxy aluminum fuel tubings on lid of plastic canisters. Those lids don't hold epoxy, as like as most plastics. But metal canister is allright for the job. I had one metal film canister, Kodak brand, but lose it.

Yes, epoxy doesn't hold it, but you can screw in a cheap fuel filter and attach a piece of fuel line on each side of the filter - the inner one will be the pickup tube, the outer one goes to the engine as usual.

getback Fri Dec 04, 2020 4:45 am

Sounds interesting hope to see the finally product , If you build it first how will you get the thinned epoxy to the inside ? Smile

Levent Suberk Fri Dec 04, 2020 5:41 am

dirk gently wrote:
Levent Suberk wrote:
Thanks for this, but I can't epoxy aluminum fuel tubings on lid of plastic canisters. Those lids don't hold epoxy, as like as most plastics. But metal canister is allright for the job. I had one metal film canister, Kodak brand, but lose it.

Yes, epoxy doesn't hold it, but you can screw in a cheap fuel filter and attach a piece of fuel line on each side of the filter - the inner one will be the pickup tube, the outer one goes to the engine as usual.

Very good idea, thanks.

Levent Suberk Fri Dec 04, 2020 5:47 am

getback wrote:Sounds interesting hope to see the finally product , If you build it first how will you get the thinned epoxy to the inside ?

I build an open box first, then brush thinned epoxy. I also brush thinned epoxy on lid of that box -I mean one side of fuel tank-, then assembly it. After assembling with epoxy then I brush thinned epoxy on outside of completed fuel tank.

Levent Suberk Fri Dec 04, 2020 5:54 am

I have no aluminum or copper tubing, need to order some. Can I use carbon fiber tubing? Carbon fiber material is nitro fuel proof? I don't want to wait carbon fiber tubing immersed in raw fuel for months to see whether it's fuel proof or not.

germanbuddy Fri Dec 04, 2020 6:20 am

...... Can I use carbon fiber tubing?

You better not do so because it will block your NVA .
Tiny parts of fiber etc. etc. .
Inside tube surface is not shiny like outside and will not be fuelproof in the looongrun.
Tiny cracks + Methanol find its way.

Stay with copper 3mm OD - 2mm ID tubes.
Accessible Aluminum tube is just to prone the size we need.
Brass dont work either , mentioned this earlier.

sosam117 Fri Dec 04, 2020 8:17 am

Here is how I make a 35mm film canister fuel tank.
( I also use old medicine bottles as well -- same way).

I do like the transparent canisters to see inside it.

Photo #1 is the things you will need:

1.) drill a 3/32" diameter hole in the top of the cap (lid)

2.) drill a vent hole 1/32" diameter ( or so - just to let air escape)

3.) angle the one end of the copper tubing

4.) cut the surgical tubing (1/4" o.d. x 1/16"i.d.) to 3/8" length

5.) slip the surgical tubing over the copper tubing

6.) insert the copper tubing into the drilled hole in the cap (lid)

7.) slip the next length of surgical tubing over the copper tubing (topside of the cap (lid)

8.) slide the top surgical tubing all the way down to the cap (lid) to make a good seal

9.) snap cap to bottom of film canister

10.) finished photos of the 35mm fuel tank canister.

Levent Suberk Fri Dec 04, 2020 10:16 am

germanbuddy wrote:...... Can I use carbon fiber tubing?

You better not do so because it will block your NVA .
Tiny parts of fiber etc. etc. .
Inside tube surface is not shiny like outside and will not be fuelproof in the looongrun.
Tiny cracks + Methanol find its way.

Stay with copper 3mm OD - 2mm ID tubes.
Accessible Aluminum tube is just to prone the size we need.
Brass dont work either , mentioned this earlier.

Right. I thought to smear epoxy inside of tube, but gave up.

Levent Suberk Fri Dec 04, 2020 10:18 am

Very good idea for canister fuel tank. Thank you Very Happy

Perhaps a servo grommet also works for this. Huh...

sosam117 Fri Dec 04, 2020 10:41 am

Levent Suberk wrote:Very good idea for canister fuel tank. Thank you Perhaps a servo grommet also works for this.

The servo grommet may work?
It was just easier to use the two surgical tubing on either side of the copper tubing.
You just need a tight enough seal to keep the fuel from dripping out.

I may try the servo grommet on the lid of my old (empty/used) medicine bottles next time I make a fuel tank. Old Bugger

andrew Fri Dec 04, 2020 3:08 pm

Here's a link into another forum that I made some 16 years ago on how to deal with leaks and stress splitting in the Fuji cans. It is a pretty simple fix and gives a fuel tight seal.

https://www.rcuniverse.com/forum/1-2-1-8-airplanes-70/1847112-fuji-film-tank-revisited.html

Empty Fuji film canisters can be purchased online through Amazon or eBay.

Levent Suberk Mon Dec 07, 2020 1:24 pm

I cut parts from 2 mm sheet balsa. Fuel tank capacity is 25 cc / .85 oz. Size is 50 mm x 50 mm x 10 mm inside and 54 mm x 54 mm x 14 mm outside. I couldn't find copper or aluminum tubing, so I'll use a 3 mm telescopic antenna tubing. Total weight before applying epoxy is 5.0 grams / .177 oz.

Now I'll make a vacuum bag for applying %50 alcohol thinned 24 hr epoxy on parts.

roddie Mon Dec 07, 2020 5:09 pm

Hi Levent, I've been intrigued for days about this thread.. and tonight I started reading. There's some very interesting conversation. I thought that I'd add my Two Cents

(inflation)

Keep in mind, that this is not a proven idea.. but rather how "I" might go about it.

What if.. you assembled the tank (your panels..) with Copper tubing tacked in-place with CA glue. You could use CA on everything.. to tack it together.

Then maybe mix a 1/2oz. batch of thinned epoxy and inject it into the tank through the feed-tube with a syringe. Cap all tubes.. shake "vigorously".. then evacuate using a low-pressure air pump (aquarium pump?) again; connected to the feed-tube, with the vent at the lowest point. The excess epoxy will flow out the vent.. while the tank walls should be sufficiently coated. Constant pressure with an pump should insure no blockages in the tubes.

I would personally use slo-cure epoxy.. unless you can work fast.

Levent Suberk Mon Dec 07, 2020 5:33 pm

Very interesting idea Rod, thanks for this. If I add more than 50% alcohol with 24 hr epoxy, does it fully cure or stay rubbery? I experimented that 50% alcohol thinned 24 hr epoxy fully cured after a week. For full coating inside of tank it need to be near water consistency, at least glycerine like, so I think that I need to add alcohol more than 50%. What is your opinion?

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