1) I guess I drill holes through the firewall for the fuel lines??

2) What is the ratio of alcohol to epoxy for fuelproofing?? 30 minute or 6 minute??


Thanx!!

Yes, drill a hole in the firewall. It helps to countersink the hole a bit on both sides so there isn't a hard corner for the fuel line to rub against. For more info on setting up a fuel tank and the plumbing see this excellent How-to: [link]http://www.airfieldmodels.com/information_source/model_aircraft_engines/install_a_fuel_tank.htm[/link]

I prefer to not thin epoxy with alcohol for fuel-proofing. The reason is because epoxy curing is a chemical reaction, and when you add alcohol you change the chemical composition of the epoxy which changes the final properties. Yes, a little bit usually won't cause many problems, but it's too easy to get too much alcohol and and totally screw up the epoxy. It's possible to add too much alcohol so that the epoxy will never quite set up.

Instead use heat to thin it for spreading. First off, you will have to use 30 minute epoxy. The heat is going to accelerate the curing process, so if you use 5 minute epoxy you'll never have enough time to spread it. You'll need the epoxy, a disposable epoxy brush (also called acid brushes), and a heat gun. Put a "blob" of epoxy on the area you want to fuel proof and apply heat the area with the heat gun, this will cause the epoxy to thin out. As it thins out use the brush to spread it out. Keep doing this until you have your area covered. A huge advantage to this is the heat opens up the grain of the wood and allows the thinned epoxy to "flow" into the grain, giving you even more protection from fuel.

I know the heat may sound complicated, but it's a really easy step. You can do the standard engine and fuel compartments in just a couple of minutes. When the epoxy cures it will be rock hard and protect your plane.

Hope this helps

Ken