My RV8 work has been on hold the last few weeks; needed to finish up a propeller project and get the sawdust cleared from the shop so I can start painting. Thought ya'll might enjoy a look.
This is a prop for a 315 hp fixed pitch M14 radial. It is going on a custom biplane, a half-done project I'll jump back into after the RV-8 is flying. The prop is seven feet long with a chord over 8 inches.
Design is by Don Bates, via his Prop Optimizer Pro software. The code needed a modification to adjust for the reduced free-stream velocity in front of the radial cowl, which got Don interested, and one thing led to another.....nice fellow. Software output is (among other things) a set of airfoil coordinates for 20 or so blade stations. I plotted them in AutoCad and printed them full size, then made hard Formica templates.
Material is sugar maple, in 1/4" laminations. The glued blanks were the size of a railroad tie and about 100 lbs each. I made careful cuts with a circular saw and knocked out a lot of the excess wood with a chisel:
Since I needed to make
two props (have a buddy with an identical engine), I decided to do them with a propeller duplicator rather than entirely by hand. First step was carving a master blade; my own craftsmanship guru, 84 year-old Raymond Griffin attacked that project while I built the duplicator. Here's the master in the machine with a prop in process. Yes, that is a knee-deep pile of wood chips against the wall:
The duplicator gets the profile within a 1/16" or so. The rest is done by hand on a template table. Each template includes a reference mark that matches with a line on the table; just keep sanding as necessary:
I know it would look good varnished, but I may do a flox insert in the leading edge and glass the whole thing. For now I'm just gonna store it away and get back to RV work.
Building a Prop
and sold 
Linear Mode
