First Mark thank you for learned insights, points that I will remember too.
Orma a thought came to mind: on the Piper Aztec the spinner had a small hole drilled in the tip, maybe 1/8" in diameter that was supposed to increase flow into the cooling ports that Piper said they found was actually being diverted around the cowling due to the stack up of air pressure in front of the spinner. By drilling the hole in the tip of the spinner and then having slightly oversized clearance cutouts for the blades, which were constant speed so they have larger openings than fixed pitch anyway. They said this caused a suction through the tip enough to promote more airflow through the cooling ports. They also added louvers to one side to balance cooling since the venturi effect was drawing air away from the inboard side of the cowling. Maybe some louvers in the slipstream would promote more airflow through the side with # 3 cyl. Just some non-expert thoughts... Colin & Bev Rainey KR2(td) N96TA Sanford, FL crain...@cfl.rr.com http://kr-builder.org/Colin/index.html
