Time Pilot

After what seems an eternity and a few years of flying electrics first, I am close to the covering stage on my Tower 40 and need to consider fuel proofing.

I intended on fuel proofing the tank compartment but I need some opinions on the engine area and where the covering's seams will be.

First, the engine area: Is epoxy the best here? Will plastic coverings adhere to the epoxy well?

Also wondering about areas where I'll have covering seams: Is it a good idea to pretreat these areas with clear fuel proof dope or polyurethane first?

Thanks.

kdheath

Many builders use 20-30 minute epoxy, brushed into the tank (in case the tank should leak) and engine compartments, then heated gently with a covering gun. The heat thins the epoxy and you roll the fuselage around to coat everything and pour the excess out. You only need a minimum amount to cover the wood. Any extra is just unneeded weight. I paint the engine compartment with matching or contrasting paint. There are some other ways to do this, but this is the most common, I think.

If you do a good covering job, you really don't need to seal the seams. Over lap the seams about a quarter inch or so. Cover everything from the bottom up, so all the laps go down. Some of the low temp films do peel up easier than Mylar films like Monokote. If it bothers you, use an artist's bruch to paint a thin bead of clear urethane over the seams around the nose. That's where the most abuse occurs.

oscar2005

you can use any of the following to fuel proof tank and engine compartment,clear dope,finishing resin,polyurtane oil based.epoxy works but is heavy and expensive compared to other alternatives.

Newc

15 or 30 minute epoxy thinned with rubbing alcohol is a fine fuel proofing coating for engine and fuel tank compartments. Never heard of the technique of using epoxy full strength and then rolling the fuselage around and then pouring out the remainder, but it seems to me that this results in way too thick a coating that is not necessary. I thin the epoxy just enough to allow it to be easily brushed and to flow on with an epoxy brush. By thinning it this way it allows the epoxy to better get absorbed into the balsa and plywood than using it full strength.

Gringo Flyer

My Feedback: (18)

You can also fuelproof with thin CA. Just put a few drops on the surface and move it around you will be able to see the CA wicking into the wood. Super light and fast!

I have a friend who fuelproofs with monokote. He just monokotes the firewall and then installs the mount on top. I dont think this method is as good as the thin CA but he hasnt had any problems with it.

kdheath

You heat it gently with a heat gun, pour off the excess, and you get the thinnest possible coat that soaks in and seals beautifully. I bashed a plane that had been treated this way and found that the epoxy had soaked visibly into the plywood. The weight gain was minimal.

Deadeye

CA is fuel proof? Not the CA I've been using.

Gringo Flyer

My Feedback: (18)

As far as I have heard and seen I am almost positive it is fuelproof. I have seen several other folks recomend thin CA here on RCU for fuelproofing as well.

It would seem strange to use a type of glue on a RC model if it wasnt fuelproof.

Anybody tested thin CA with glow fuel and know for sure?

air mail rcu

I've use thin CA to fuelproof. Works good.

Deadeye

I have seen fuel soaked CA joints fail is all. Maybe if it is soaked for a period of time it will let go? If the model is glued together with CA, then why bother fuel proofing? Alphatic resins will let go if exposed to glow for any length of time, but those joints are usually covered up.

Newc

I would bet that the failure was at the junction of the CyA and the wood, where the fuel-soaked wood failed, not the CyA joint.

kdheath

CA debonder is supposedly nothing but nitro. As long as you don't regularly slosh raw fuel on it, it should be fine. I just can't stand the CA fumes any more. Plus I've always had trouble controlling where all it goes....

air mail rcu

After 20 odd years of using CA without problems. One night I thought I was having a heart attack. Turned out it was from the flumes. Use good ventilation.