flybyjohn

My Feedback: (2)

I am in the process of building a seamaster from plans. I have looked at the tail and some comments from this plane is that the tail can have a little flex in it. I was considering making a foam core vertical stabilizer sheeted with 1/16" balsa. Will Polyurethane glue cure in a vacuum bag? What other types of glue should I use?

Rodney

For that type of construction (vacuum bag) I'd stick with a slow epoxy. Any glue that requires either moisture or evaporation is not apt to cure properly that situation.

All Day Dan

My Feedback: (5)

John, use Z-poxy Finishing Resin and weights. Dan.

fulload

The poly gule works great when you can weigh the wing sleeves down over it. Use a credit card or something to scrape as much glue off as possible. Put the balsa skin in place and weigh it down over night. I believe the poly in this case will make a stronger wing than epoxy because it will make contact with 100% of the skin and foam due to the expanding properties. Epoxy can not contact as much of the skin and probably only makes contact with about 60% of the wing.

flybyjohn

My Feedback: (2)

Thanks for the info guys. I will have to see if the foam core vertical stabilizer or a built up sheeted one would be lighter or easier to build.

Tony Hallo

Poly glue will cure in a vacuum bag for those looking for this information. Attached are photos of an eight foot wing done in one piece.

speedracerntrixie

My Feedback: (29)

I too have used poly glue to sheet wings via vacuum bag. Worked just fine but it does not foam nearly as much. The poly verses epoxy debate as been going strong for quite a while now. IMO you will get good results with either but thinking that you get only 60% of the surface area bonded with epoxy just tells me you are not prepping the cores correctly. Personally I use epoxy simply because I like to add glass or CF reinforcements at the time of sheeting.

sensei

I too have vacuum bagged both G/G, foam, and balsa sheeted wings as well as epoxy and sheeted foam wings, both cures completely but I prefer going the slow cure epoxy route.


Bob

BMatthews

John, just to muddy the waters a bit I'm going to suggest another option. If you go with built up instead of balsa sheeting use thin plywood. I've done two T tail 2 meter gliders that I wanted to be stiff yet light and in both cases I opted for built up with 1/64 ply skins. The slick thing is that lower edge tails of the plywood extended down over the carbon boom I used on one version and into the hard balsa used for the sides of the other to provide a really solid lower joint to the T tail.

The slick thing is that the 1/64 ply weighs about the same as medium density 1/16 balsa. So there is no real weight penalty but the fin ends up much more stiff than if I had used balsa.

On a bigger and heavier model I'd bump the skins for the fin up to 1/32. But there's no need to use anything thicker at all.

sensei

For those of us that build very large models with foam core wings 1/16 medium balsa sheeting is a superior way to go because there is enough material to perform a good needed spline sanding on the wings truing the surface and further reducing weight as we balance the weight between the two wing halves as we sand.

Bob