I am building a 12 foot Telemaster. This is my first ever RC plane build. I need to use the plane as a tow vehicle for a special project.

My biggest question is do I NEED to use Epoxy where they call for it in the instructions? Can I use CA instead and get the same strength?

Any light you folks can shed on the subject would be helpful.

Yes

No

Besides what ptmac3 said about CA and Epoxy, you may want to consider using aliphatic resin for the construction. Due to the size of the airframe you will go through a lot of glue and TiteBond II, Elmers Carpenter or similar high quality carpenters glue will be a lot cheaper. IMO, I feel that over time it may be better as it has a bit of fexability that CA doesn't have and will absorbe the vibrations better over a longer perior of time. I have had CA fail on a plane after 6 years of use, but has a couple of planes nearing 30 years old that the aliphatic resin is holding together just fine.

Hogflyer

Over time you will develop a feel for when to use CA, when to use epoxy, and when to use wood glue. Unfortunately this will not help you with your first build. For now, I would say follow the instructions.

CA works well with balsa, not so well with hard wood, and poorly with plywood. Something to do with the chemistry of the wood I suppose. Epoxy is needed when the pieces are a poor fit and there are gaps to be filled. Epoxy tends to be heavy as you typically use a lot of it compared to CA or wood glue. Wood glue has advantages and disadvantages too. You will get the idea after building several models.

Emphasis on "a lot"

I've found that CA is actually a bit brittle compared to aliphatic (sp?). I've found that if you put the right stress on a CA joint it'll snap apart, where aliphatic doesn't. I don't have any scientic proof, or precise examples to cite. But that's my "take."

Epoxy also tends to NOT flow into the wood grain, creating a "surface strong" joint that will pull apart under load. I built a giant Stinger that was powered by a G-62. I used only thin and thick CA and it's still flying after 15 years.

I only use epoxy for metal and glass joints, or for fuel-proofing.

CA is stronger, lighter, and easier to work with.
Epoxy is heavier, hard to mix properly, messy, and not as strong on wood joints.

Dr.1

Thanks for the input everyone.

This will likely be my last build as well. I am only building it to use a tow plane for something totally different that will likely be an all Carbon Fiber glider.

I have to dissagree with DR1Driver.
Epoxy, if used right, is stronger than CA in certain applications. Epoxy can flex where CA is rigid and a bit brittle.
I started off using epoxy and CA in high power rockets. I am talking about rockets over 3lbs and personally up to 11lbs than are capable of supersonic flight.
I have seen beginners in that sport use CA for their fins and watched the rockets turn into confetti.
I would never consider CA for any high stress application, that includes high power rocket construction (fins and engine mounting) and firewall, landing gear blocks and wing joints in airplanes to name a few.