Before gluing the firewall permanently to the fuselage, I needed to figure out where and how to mount the electric components. Placing the motor over the plan, I noted that there should be a little over 2 inches between the firewall and the motor back plate. Normally, in an electric conversion, I fabricate an aircraft ply box that bolts to the firewall and onto which the motor is fastened. However, with this short an offset, I decided to use standoffs. Rustling around in a “leftovers” bin, I found four 2 ½” long, ½” diameter aluminum tubes.
Now, the downthrust for the Cub is built into the fuse, but the side thrust has to be created by trimming the tubes to different lengths. Consequently, the left standoffs ended up about 1/16” longer than the right producing about 2 degrees of right thrust. Using 10-24 hardware, I made up a mounting “kit,” shown below, for permanent installation after the firewall got glued in.
The ESC fit snugly beneath the motor and will be fastened to the firewall with #4 self-tapping screws. With everything mounted, I test fit the cowl and the motor shaft poked out where it should and everything else tucked neatly inside.
Time to glue the rest of the fuselage together.
First standoff temporarily installed to check motor position against the plans.
Shorter, right standoffs up top; longer, left ones below.
The motor mount "kit."
Motor mounted, firewall vertical. Well, almost: it was off by -0.1 degrees.
There's supposed to be a photo here that I cannot get to upload despite multiple attempts. It would have shown the motor pointing 1.7 degrees upward (right when viewed from the top) resulting in a total of 1.8 degrees of right thrust.
Everything fits!
Motor shaft dead center, nothing else sticks out.