The firewall is next. First step is to mount the motor. I am using a Plettenberg Evo. The firewall has a hole near center but offset to one side. I took a chance and thought that this should be the center of the motor axis, shifted to the left a bit to make up for the right thrust. The mount for the Evo has 3 threaded holes (4mm) on a 20 mm radius from the center of the motor. I used a ruler and protractor to mark all three holes. After I realized that the rear mount comes off the motor and could have been used as a template to mark the holes. The 4mm screws have to be short or cut so that they do not interfere with the motor spinning.

The first time I inserted the firewall motor combination into the plane it came about 1/2" short of where it needed to be. In addition I realized that the motor could only go in and out through the nose ring once the firewall was in place. The wooden nose ring would have to be cut back to allow this. Get ready to make a lot of sawdust. See the before and after picture of the nosering.

Next is to size the firewall to fit a bit more foward. I use a spinner back plate to keep centering the motor and sand down edges that are coming in contact with the fuse. There will be a space around much of the firewall, I just sand the areas that hit and eventually it fits better. Again get ready to make some dust and take some time gettting this to fit properly. Each trial fit should bring it a little closer to where you want it. I use a 1/16" spacer between the spinner back plate and nose ring. I like the firewall to go just a little further than I need it and push it back slightly. This way I am usually not deforming any part of the fuse. Again 30 min epoxy and microballoons were used to glue the firewall in place. Spinner taped tight to the fuse. This is drying right now. After it dries I will add glue/microballon filets tot he front and back of the firewall where needed.

Between cutting down the firewall to fit and opening up the air flow holes a bit the final weight of the firewall before gluing it in was 34 gms. It started at 41 gms.