maktec

My Feedback: (29)

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 resin, 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

EdwardB

My Feedback: (6)

Depends on what you're trying the finish product to look like. Since balsa has a very open grain, generally, bare balsa that's painted (whether with resin or some other paint product) is hard to fill and sand, and over time will open back up and look cracked or checked. The fiberglass cloth, along with the resin, makes a much more stable surface, will stay looking good over time, and is more durable. Lightweight fiberglass cloth is available, some as light as 1/5 - 1/4 oz per yard, and add very little weight. If your goal is to save weight be leaving out the cloth, and it's not going to save much.

khodges

My Feedback: (1)

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 .

CafeenMan

First, I strongly disagree with a fiberglass finish being heavier than a standard weight film such as Monokote. If you do it right, the finished weight is comparable.

The main reason to use a covering on solid surfaces is to put a layer over the grain which results in a lighter finish than if you try to fill the balsa. Balsa has very deep grain that takes a lot of filler if you want to get a glass-smooth finish. By covering, I'm talking about coverings applied with a liquid finish such as fiberglass cloth, silk, tissue, etc.

The way to keep the weight down is to sand off all the filler except the part that is actually filling. Anything sitting on top of the cloth is excess and should be sanded off.

Spray paint in light coats and sand between coats. The reason some paint jobs end up heavy is because people try to get good coverage in a single coat which instructions always say not to do but people do anyway.

The bottom line is that if you want a scale, painted finish, then film won't work. It will always look like plastic. If you want to paint, then always use a covering to save time and weight.

Here's how to apply fiberglass cloth

maktec

My Feedback: (29)

THANK YOU VERY MUCH,
that is lots of help. looks like I am going to fiberglas the plane.
George

Ron Kinsey

Hello Maktec,
I used this process on my scratch built OV-10 Bronco. (pictured) I wanted to paint the entire plane, but didn't want to use the cloth because of the weight factor. I encountered no adverse affects, and it left me with a hard, smooth surface I wanted, Although there was a lot of sanding involved. But isn't there always...Good Luck!

Spicoli

I have found if you dont use the glass cloth the grain of the wood will start to show through eventually.
The fiberglass is the lightest part of the finish.
I agree with Caffeenman,a properly done a glass finsh is comparable to a plastic finsh

Sense963

My Feedback: (10)

[8D]
Cafeenman, GREAT website on fiberglassing. I am going to glass my AstroHog fuse in the near future. Never done it before on MY plane, just got tutored once by a master craftsman. He was glassing the wing on his 1/4 scale designer Cessna 172. Your website is a great resource, and has lots of great 411. Thanks!

CafeenMan

Thanks for the compliment. I don't think you can glass a Hog without modifying it. Isn't it open construction? Open structures can't be glassed so you'd have to sheet the fuselage.