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 Sailplane Construction Project Session #67

Comet Sailplane Project
I spent most of the day fussing with the fit of the cowl and making cut outs for the cylinder head, exhaust, and needle valve. When I installed the McCoy 60 in the motor mounts, they were spread oh so slightly. However, this did caused the cowl interface with the firewall to be slightly askew. So I worked for several hours determining what and where the interference problems were and one by one relieving them until the interface was again restored.
The cut out in the top of the cowl for cylinder head is shown below. The gap between the cowl and cylinder head is actually even all the way around. However it does not appear to be because the picture was not taken squarely over the cowl opening.
This view of the right side of the cowl shows the initial exhaust opening I made today. I realize it may have to be larger to keep the hot exhaust gases from burning the edges of the opening. I lined the hole in the cowl where the needle valve goes through with a short piece of aluminum tubing as you can see below. 
Tomorrow I will glue two 3/16" balsa sheets onto the front flat face of the cowl, rotating each grain 90 degrees to the other, to form the rounded front end of the cowl. I still have not decided on the number and size of exit cooling air openings in the cowl, except that there will be on the rear bottom to let the oil drain out............................Tandy

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