Sailplane Construction Project Session #63
The Sailplane cowl is quite long and open as
evidenced by the 4-1/2" distance between the front and rear cowl bulkheads
as shown from the left side below. Therefore, it was felt that some internal
support structure was needed to (1) to provide both torsional as well as
bending rigidity, and (2) to keep the external "barrel" planking from trying
to bow or draw in over the long distance with no other intermediate
bulkheads. It should be noted that contour balsa will be added along
the diagonal so as to also support the external planking.
This view of the structure shows the vertical
location of the McCoy's exhaust on the right side. An exhaust extension will
not work in this application because of interfering with the attachment and
removal of the cowl. Therefore, a clear opening on the right side of the
cowl must be provided to permit the hot exhaust gasses to exit out the cowl
into the free stream air.
This view of the structure shows the location of
the McCoy's exhaust from the top. The distance from the engine's exhaust
exit plane out to the outside of the cowl is approximately 3/4". The real
question here is how big to make the opening so the hot exhaust gasses won't
char or burn the edges of the cowl opening.
If you have any experience with cowl exhaust
openings, I sure could use some advice right about now before I start
planking the cowl..........................Tandy
Click Here to go to the
next page (64)....