Just getting back into CL - built a pair of 1/2a Flite Streaks from scratch. On one, I installed a Perfect fuel tank to service a Cox reed valve engine (don't know the version of the engine - has the needle / intake in a plastic plate attached directly to the crank case.

Anyhow, this Perfect tank is about 1 1/8" long, 3/4 inch wide wedge type with two vents (one on each top and bottom). I only get about 60 seconds of run time, whereas my other plane of the pair has a Golden Bee that runs for just under three minutes.

Does anyone know what the relative fuel capacity of the Perfect and Golden Bee tanks are?

Oh, and why would the Brodak butyrate dope under the firewall soften and dissolve away within minutes of getting fuel on it? It cured for nearly three weeks!

Thanks in advance.

Keefer,

First, which tube are you feeding from?

Second, Brodak dope, like any other butyrate dope, is only resistant to Nitro Methane. The higher nitro content in 1/2A fuel attacks it quickly.

I'm drawing from the front pickup (leading down the crown of the wedge to the rear). I've made sure the tank was full.

If Brodak is resistant to nitro-methane, why would a high-nitro content fuel attack it so quickly?

Only Urethane and Epoxy are actually fuelproof. Butyrate can stand the alcohol, but not the nitro. Most CL guys use 10% nitro or less, but the 1/2As are happiest on 25% or more.

That is how it is.

You can put a coat of clear epoxy over the dope in the critical areas to solve the problem.

I think the Golden Bee is 11 ccs, and the Babe Bee 8ccs. Also, I think you may be blowing fuel out your vents. Cap one vent with a piece of fuel hose with a b-b or screw jammed in it.

I estimate that the wedge tank you have is 1/4 oz, or 8cc.

Actually the larger Cox tank is 8cc and the smaller Baby Bee type is 5cc. The SAM Texaco guys went through all this a while back for the rule change.

That tank sounds pretty small. I'm guessing but at 1 1/8 x 3/4 it's probably only about 1/2 inch thick. That being said this is less than 1/2 oz I would suspect. A minute still sounds short but with the higher nitro fuel it may be right.

I tried to watch the vents closely for fuel being drawn out in the air stream and saw none. BMatthews, you're right - it's about 1/2" thick.

DesignMan - I'll plug one vent and see what happens.

Can I put Lusterkote clear over the butyrate dope?

Can I put Lusterkote clear over the butyrate dope?

Test first. Lustercoat eats up lots of other paints.

jess

I don't think Lusterkote is all that fuelproof to high nitro either. Clear Epoxy (30 minute or laminating, not 5-minute) or Oil base (not the new water base) clear Urethathane as an overcoat. Epoxy will be OK in 24 hours, Urethane should set up for a week!!!

I have been using the Epoxy that they have at craft stores for "deep" finishes. It seems to be very fuel proof, very clear, and can be thinned with a variety of solvents.

Always, ALWAYS!! do test panels when using an unfamiliar finish combo. Trust me, you will live a longer, happier life. I have a beautiful "hangar queen" brand new model I never dare try to fly because the urethane top coat will peel off the color NOW!

FYI, it was epoxy over Rustoleum Metallic Blue. No problem of bubbling, the finish is fabulous, it will just peel up at a touch.[:@]