While the pit crew was napping, I started working on the dummy radial.
First I cut a 7-sided polygon from 3/8" balsa to form the backside of the crankcase. Then hollowed out the center to clear the Wolf engine.
I cut a second 3/8" polygon for the front side and again cut clearence for the wolf engine. Then cut 3/8" x 1-1/2" balsa pieces to fit between the two polygons to form the flat sides of the crankcase. I then test-fit it on the airframe and made sure there was proper clearance for the Wolf engine. I also tossed one of the Williams Brothers cylinders on it to check the overall size.
Then I started working on mounting it. A piece of 1/16" ply was cut to be 1/2" bigger all the way around than the engine mount. I then cut out the center to clear the Wolf engine.I screwed this ply plate to a couple pieces of 1/2" x 7/8" MDF and sanded them smooth around the perimeter.
While still screwed to the ply mount, I glued these MDF pieces to the firewall.
A dremel with router attachment made quick work of cutting recessed rings for the cylinder heads to glue into.They are a bit rough but will get filled with glue.
The crankcase was then slid over the Wolf engine and glued to the plywood mounting plate. I was excited to see what the finished engine would look like, so I set the dummy cylinders in place. For the cylinders, I am using (5) Williams Brothers 1/5 scale Wasp cylinders.
The final piece was the front of the crankcase. I cut two rings, one from 3/8" balsa the other from 3/4" balsa, that had a 3-1/2" outer diameter and 1-3/4" inner diameter. The 3/8" balsa ring was cut to clear the last bit of the Wolf engine then was glued to the 3/4" balsa ring. The two together were sanded to shape to creat the front of the crankcase then glued to the existing assembly.
I'm happy with the finished product so I removed the radial and the cylinders to finish the crankcase with fiberglass. Unfortunately I was out of lacquer, so I figured some extra Stits Poly-Brush would do the trick this time. Tomorrow I will sanding and priming and filling to get it ready for paint. Meanwhile, the firewall area of the fuse can now be sealed off.