Hatz Biplane Association

I'm working on the cockpit openings. In my only significant departure from traditional materials and methods (so far), I am using unidirectional carbon fiber to stiffen the rim of the cockpit openings.

I've always felt that every open cockpit I've been around is too fragile and flexible around the combing. A passenger could easily damage most of the cockpits I've seen.

I just can not imagine bending a steel tube precisely enough to fit the cockpit opening shape well. So I decided to mold in place a unidirectional carbon fiber rim on the cockpit opening. I made a dam from tooling wax that kept the fibers where I wanted. There is a 1/2" x 1/4" build-up of carbon on the inside and outside, resulting in a 1/2" x 1/2" square bow around the opening. Because epoxy bonds rather poorly to aluminum, I followed up with a #2-56 flat head screw every 2 1/4 inches or so, through the carbon with a nut on the inside. Of course all this will get covered with a padding tube and wrapped with leather.

The cockpit rim is really stiff. Coupled with the aluminum bulkhead braces on the inside, I think you could sit on the rim of the cockpit with no harm.

Then, it was time to cut out the door! Gulp. Turned out well, I am jazzed. Now I have to do all this again on the front.