Does anyone have an approximation on how much "weight" fiberglass and painting adds to an aircraft? For example, does a typical 9lb model come out at 11 lbs after glassing and finishing?

ak,

That's a loaded question... you'll get lot's of different answers. Mostly depends on "how good you are" at doing it. The key is applyling it in very light coats, both glassing resin and paint.

The painting process might increase your weight more than anything, depending on what you use. Automotive paints give the best finish but are much heavier. Two-part epoxy paints are extremely heavy too. I've not used Nelson Hobby color paints, just the clear, but it's very hard/durable and extremely light. Personally, as a warbird builder, I like latex house paints with a clearcoat of Nelson Hobby clear.

I'm building a warbird now and will be using Minwax waterbased polyurethane to glass with, latex paints to color, and Nelson Hobby to clearcoat. I just wrote an article describing the process and gave test results on weight gain. Using my process, in theory, I'll gain less than 2 lbs on a 23 pound, 85" warbird. With different resins, techniques and paints, that could easily have been 4 pounds or more. You can read the results of my weight tests at:

http://www.renderwurx.com/rc/glasstest/index.htm

Good luck,

Neo

I agree with Neo. If you do it right, glass can weigh so little that it's negligible compared to other coverings. I built a plane about 6 months ago that is glassed and then painted with clear polyurethane. I used about 1/2 ounce of resin in total and less than an ounce of paint.

Only the fuselage and fin were glassed though.

This is the plane:

http://www.airfieldmodels.com/my_stik_30.htm