Mounting the Radial Cowl

Setting up the mounting scenario for the radial cowl is a real excersize in patience and creativity. I wanted something that was very strong and reliable, functional, easy to access, yet not obtrusive when viewing the plane on the flight line. I started out by mounting the engine back onto the firewall, then building a small box over it that would eventually be used to mount the electronic ignition and battery to.

Anticipating airflow/cooling, throttle linkage, wiring, switches, choke linkage, and other issues... I planned out my attack. My final approach was to have 5 hard points that would be used to secure the cowl to the firewall, only 2 of which would involve any external screws. It works by having a steel L-bracket at the top that is used to align the cowl and support it from the top. You just slide the bracket into a wooden channel that's glued inside the top of the cowl.

Once the cowl is slid onto this bracket, you align the other 4 hardpoints with their respective screw holes. The ones on the sides have L-brackets glued to the inside of the cowl which screw to wooden blocks that are glued to the firewall ring. The mounts at the bottom are L-brackets glued to the firewall ring wich align to screw holes in the bottom sides of the cowl.

This allows for a mounting procedure whereby you slide the cowl onto the top bracket, run two 4-40 screws through the cowl into the bottom brackets, and then two more 4-40 screws are threaded into the interior top-side brackets. These last two screws are accessed through the now open cowl louvers, so that the screws are not visible on the outside of the cowl.

This process, along with the big "gaping hole" on the bottom of the cowl, allow me to slide the cowl straight on from the front without tiliting... something that I'll need to be able to do in order to mount the cowl with a dummy radial on it. Otherwise the prop shaft would not clear the dummy radial if I had to tilt the cowl when mounting it.


"Adding a Dummy Radial"