The propeller hubs as designed were to have been installed before the wing is assembled. I didn't like that method because it prevents
proper filling and painting in the area so the large end of part 39 was ground off, as following photos will show. To keep proper
spacing so the propellers will turn, the hub (40) and part 37 were assembled first and then the large end of 39 was ground off.
Washers made from plastic card using a hole punch and the screw shown will be used to install 40 after parts 37/39 have
been fitted during wing assembly.