ORIGINAL: maktec
Hello all,
I am building a 1/4 scale Cessna 182, has bulsa covering, Just wondering what you think, or anyone has done this?
"Paint" the entire surface with fiberglass rosin, with thin coating only, no fiberglass masking, just the rosin>>>>> making the surface smooth after sanding, Or would it add undue weight or other problems I am not aware of?
Any ideas?
George
Happy Flying
If done properly it will make a very smooth, very tough surface, but you can't do it it in one, or even two coats. Adding fiberglass cloth will add puncture strength, but will add more weight because it will allow a thicker coat of resin in order to fill the weave of the material. One thing you could consider if you really want to do this is to use thinner balsa to sheet the fuse and wings, or use 1/64 ply (weighs the same, per square inch, as 3/32 balsa). You should be very careful if you opt for the ply, it will buckle if not applied just right and surface will be wavy, but it can make a very smooth surface.
Fill any voids and cracks with Balsarite filler, and then sand with 160 grit. Use a thin resin, "paint" the plane and let it dry, and sand with 220 grit dry paper, and repeat a second coat and sand with 260 grit. Whatever grain is left will fill in with a 3rd coat, sand with 300 grit, then a 400 wet sand. tack it well and see how smooth it is. Add your panel detail and whatever else (such as the control surface corrugations, sand again with 600, tack and paint.
This type finish WILL be heavier than a film covering, but you'll never worry with it wrinkling. I used to build high-power model rockets and used this technique on the body and fins; the fins took a good beating from rough landings and they always came out in good shape .