Hatz Biplane Association

I'm looking for information from you guys that have knowledge and experience working with fiberglass. I'm familiar with the moldless method which seems to be the best idea. I would like to find out what kind of foam to use and weight of cloth and a good supplier. Firewall forward I want the look of a J-3 Cub with exposed cylinders. I'm considering laying up a nose bowl then completing the cowl with sheet metal or the building the entire cowl from glass. Aircraft Spruce has a few how-to DVD'S which I think will help a lot. I want to keep it light and hopefully be successful on my first attempt. By the way thanks for the input on the covering and finishing post. Leaning toward the Airtech system.


Kevin Conner

Hi Kevin,
I did the moldless way for the nosebowl on my last project. It was kind of a no brainer. I mounted a piece of plywood to the engine inside of the finished cowl position. I glued 3" Styrofoam insulation board to that and carved away to get my finished shape. At that point you can use some drywall compound to make it smooth if you want the inside to look nice. I glassed the outside with three layers of cloth (don't remember what weight) using epoxy resin, although polyester or vinylester will also work. Once cured, trim the aft edge to where you want it, remove from plane and dissolve out the foam being careful not to use a solvent that will attack the resin you used. The cooling openings were in the pattern before glassing but the intake was added later using a coffee can as a mold it. Finishing starts with sanding and then a filler (microbaloons+resin), primer and paint.
Good luck,
Al

I remember seeing a cowl built up on a Hatz just like you're talking about doing, Kevin. It's in one of the earlier Hatz newsletters from way back. It was pretty neat looking with a profile that blended from the spinner back to the cowl and on back to the firewall. Very slick. It had exposed cylinders, too. Kinda reminded me of that WW1 German fighter that was all plywood.

Al, it looks and soumds like your cowl build was a fun project! Turned out nice!