Hello all,
I'm working on my first 2m + plane. It is the Quality Fiberglass Pulsar XL. It has white foam core for the wings and will be sheeted with balsa. The instructions are very vague and when they do call for a particular type of glue, I've found that that glue is either not made any more or very hard to get. I will be using weights to keep the sheets firm against the core, cause I don't have bagging capabilities.

I haven't found much in the way of info on what type of glue to use for the sheeting process and everyone I've talked to has an opinion on what may or may not work initially or hold up.

Question #1
Will thick Zap-a Gap CA work with gluing the sheets together or is something else better?
I'm trying to keep the glue from wicking to the exterior face thus creating hard spots when sanding

Question #2
Can I use Elmers wood glue to adhere the balsa sheets to the white foam and will it hold up in the long run regarding heat, cold, stress?

Question #3
I do have to glue in a strip of 4 oz Fiberglass cloth to the TE of the wing. Does regular 2 part epoxy work, or should I look for some special lighter type of laminating epoxy.

Thanks for any help

1. Use Elmer's Wood glue; it is much more sandable.

2. Yes.

3. Two part will work well as long as you don't pourit on.

This is my preferred method.

I use polyurethane glue, either Pro Bond, or Gorilla available at just about any home building supply store.

There is no need to edge glue the balsa sheets together. Make sure there are no large gaps when you place the sheets edges together. Place the sheets together and tape them so that they will not separate The taped side of the sheets will be the outer surface of the sheeting.

With the polyurethane glue, smear a thin film on the wing cores with either a playing card, or a foam brush. In a low humidity environment it may be beneficial to apply a very light mist of water to the side of the sheeting that will be contacting the foam. In southeast Texas this is not needed. With the core in it's associated shuck, place the wing sheeting on the core that you just applied the glue to. If you get some practice you can do both sides at once, but for your first time I would just do one side at a time. The core and shuck must be on a flat surface and the core must be placed squarely in the shuck. I usually place a cut piece of 3/4" ply on top of the shuck and weigh it down with bricks. Let it sit overnight. When you remove it the next day you will find that some of the glue has foamed into the joints of the wing sheeting. The excess glue will sand off easily and the joint will be almost invisible.

Repeat for the other side. Trim the sheeting off, add leading, trailing edges, and tips.

You will find that the polyurethane glue is much like epoxy to work with, but is lots cheaper and IMO gives a superior bond as it foams into the foam structure.

Vince

That solves it then, and I have a lot of elmers.

Thanks

Another good tip, Thanks alot

The older Sig kits such as the Kougar and Kommander include very good instructions on how to sheet foam wings. They recommend Core Bond - their own brand of latex contact cement which is probably just relabeled LePages or similar. I found using the contact cement pretty easy, and got excellent results on 3 Kommanders, a Kougar, a Komet and a Tri Star. Does their method stand up?? Definitely! Some of my jobs are well over a decade old and are standing up very well.

Regards,
Kelly

3M formula 77. It's been the best for me

I think 3m super 77 (at least newer stuff) will melt foam if applied wet. 3m does make spray adhesive that wont but i dont recall the number.

I like probond also, It kind of drives itself down into the crevices between the foam balls as it expands.

I use ProBond for almost everything.

-It adds time to building but pays for itself in repairs down the road.
-It ends up weighting less than epoxy for gaps and corners.
-And since it is a polyurethane it resists fuel.

I have seen a test on a broken wing that had the foam rotted out and left the penetration of ProBond. It was amazing!! This stuff really gets in there.

Check this link for more interesting info on choices.
http://www.scaleaero.com/probondwingskin.htm

I always use SIG core bond with excelent results