Moved this over from Composites and Fabrication as noone seemed to be able to respond......Starting soon, so all thoughts are appreciated:

Fiberglass Cowl Construction (post # 1)

I am about to undertake a project to construct a fiberglass cowl using the "lost foam" method for a kit that comes without a cowl. While I have researched most of the threads that contain this subject, I did not reach any conclusions on weight of cloth, best type of foam for plug material or layers recommended. So, without beating a dead horse, I would like input on the following:

1. Should I concentrate on one weight cloth with multiple layers or vary to lighter cloth with the last layer or two? This will be a 40 size sport plane, so I want to keep the cowl light but sturdy.

2. What type of foam is the best plug material? I have heard of people using blue or pink foam found at alot of homecenters to guys who take an old ice chest or packing styrofoam and layer it into a big cube and start sanding to shape.

3. Resin is according to everyone's preference I'm sure, but what about micro balloons to fill the weave and help with the smooth finish?

4. Foam removal. Everything from gasoline to acetone has been suggested. My plan is to use dremel tool and pick to get as much as possible then clean it up with some sort of solvent. Thoughts?

5. Finally, just looking for thoughts on this process. I saw it somewhere....I plan to bolt my cube of plug material to the firewall. After trimming and sanding to desired shape, will remove the plug and begin the glassing process. My plan is to determine the depth by trial fitting the engine to find length from firewall to prop hub. That will give me the minimum critical length to the prop hub. Adding to that length will give me what I need for overlap onto the fuselage. Does all of that sound right?

Thoughts, comments and suggestions are welcomed from all.

John