Sailplane Construction Project Session #67
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
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