In particular, making a wooden propeller for the five cylinder rotary engine.
I made a simple propeller using 5 different layers, 3 layers of walnut and 2 layers of plywood. So actually more than 5 layers.
The propeller was drawn out very simply in form and then I copied the outline 5 times and on each sketched a simple outline for each of the 5 layers. This minimised the amount of wood that was needed and at the same time allowed me to create the rough form of the airfoil. I clamped all of the pieces together with titebond between them. I left the layers clamped for 24 hours before I started the next stage of sanding.
When sanding the propeller to shape it is important to approach this in stages and continuously rotate from one blade to the next. Swapping from one side to the other will allow you to get consistency between the blades.
The first propeller that I made was just slightly thin on material on the roots of the blades and this resulted in some steps in the layers – I must admit to using a wood filler at this point as I had put in so much time that I just did not want to start from scratch. As this is a decorative propeller I was not so worried, but will make some more to develop the plans and prove a point.
To get the hub true and circular in form I made two large washers from mild steel and clamped these either side of the propeller with a 6mm bolt. I then filed the wooden hub back to the steel washers.
Plans for the 5 Cylinder Rotary Engine
This is a tiny five cylinder rotary engine designed to run on compressed air/steam/CO2. This engine runs fabulously on around 10psi of compressed air and happily swings an 8.5 inch propeller.
- 9mm bore
- 9mm stroke
- 85mm overall engine diameter