3D Hobby Shop YAK55, Assembly Manual, Page: 35 / 46

Cowl Installation
If you are setting your Yak up for gasoline power, the cowl must be cut to allow clearance for the cylinder,
spark plug, and muffler (if canister is not used) of the engine. We recommend the use of a dremel rotary
tool for this step. Use eye protection and work in a well-ventilated area. Use a piece of stiff paper or card
stock for a pattern as shown below
Attach the cowl to the fuselage using three 3mm bolts from the back of the fuselage former and 2 wood
screws from the bottom through the alignment tabs. It is advised to harden the wood of the lower
mounting tabs with thin CA for strength. A slice of glow fuel tubing behind the washers will prevent the
screws from loosening during flight without requiring the use of thread locking compound on these
screws.
The easiest way to cut a cowl for gasoline engine installations is to use cardstock to make a cutting
template for marking the cowl. In the photos below, you see that we have taped a piece of cardstock to
the bottom of the plane and we have carefully traced around the sparkplug and muffler. Locating marks
are made on the cardstock so we can remove it from the plane to cut these openings in our template and
then replace it on the airframe in the same location. We carefully cut holes into the template and check
the fit of our template onto the fuselage and engine. Then we use our newly created template to mark
the location for cuts on the cowl.
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