Hinge Points with Foam-Core Wings?
 

Hello,

I am in the process of trying to finish a Kyosho AT-6 ARF, and repair a little error I made. I made the mistake of using regular CA to glue the ailerons, and now on one side the glue apparently ate away some of the foam in the wing.
Im thinking of taking the CA hinges out, filling the spaces in the wing in, and using hinge points instead.

Do hinge points work OK in foam core wings? Or does anyone have any other ideas on how to repair the wings and get the hinges to glue in nicely?

Thanks
Dave

RE: Hinge Points with Foam-Core Wings?
 

I've had good results with drilling a 1/4" hole through the TE down to the foam core. Then using a 1/4" brass tube to cut about and 1" to 1.5" into the foam core. Then epoxy in a piece of 1/4" hardwood dowel and trim flush. Now you have a good solid place to drill into and secure the hinge points to.

RE: Hinge Points with Foam-Core Wings?
 

Most guys I know, just poly glue the hinge point in the styrofoam, no dowels are used. The barbs on the hinge point, and the poly glue would be stronger than a smooth dowel IMHO.

RE: Hinge Points with Foam-Core Wings?
 

Depending on how much ca you used, you can have from a small to a very large void inside the wing. It's best to fill this void back up if at all possible. A good material to do this with is expanding insualtion foam that you can get in a spray can at the hardware store.

Test a small piece of foam for compatability, and if it's ok, squirt in a very small amount of the foam and let it expand and set up. Trim off any excess and install your hinge.

RE: Hinge Points with Foam-Core Wings?
 

Someone at the RC field suggested I fill the voids in with a mixture of epoxy and microbaloons, then install the hinge points. They thought the foam might not have enough density and strength for this application.

RE: Hinge Points with Foam-Core Wings?
 

I agree with Deadeye. Thats the way I do it. The poly glue, I use Gorilla, expands a bunch. This fills the voids. I put the glue directly into the hole and let it expand to fill the void. As the glue creaps out of the hole I use a cotton swab to take up the extra glue. The hinge point has some grease on the hinge so it will never have a problem with the poly glue.

This will be stronger and lighter then any thing else you can do using hinge points.

hope this helps

tonyc

RE: Hinge Points with Foam-Core Wings?
 

The generally accepted way of installing hinge points in a foam wing is by adding "hard points" such as hard wooden blocks where the hinges will be mounted. I'm not saying that it's required, or that the poly glue method isn't fine, just stating what I've seen and heard.

(And there IS a good chance that the CA dissolved a lot of foam in the wing.)

Good luck with the repair.
Dennis-