The Prop

The propeller is in!  We have decided on a NG-D 3-blade pusher, ground adjustable pitch propeller from E-Props.  The blades are full carbon as is the hub.  The diameter is 125 cm.  It’s rated for a max rotational speed of 3200 RPM when driven by electric motors.  In this blog we describe the process of making an adapter plate and installing the prop.

Rear view of the fully assembled and mounted propeller.
The prop kit included the blades, 2-part hub with flange plate, bolts and washers, digital protractor for adjusting pitch, and an instruction manual.
The full up weight of the prop assembly, including the adapter plate. The only parts missing from this weigh-in are the are 6 M6x24mm socket head cap screws.
This is the CAD model of the adapter plate. It allows us to attach the hub which has a 6M8d75 bolt pattern (common on Rotax 2-strokes) to our electric motor which has a 6M6d50 pattern.
Screenshot of the CNC path required for machining the prop adapter.
We used our X-Carve CNC router to machine the adapter plate from 1/2" 6061 aluminum stock.
Aft view of the adapter after some polishing.
Forward view of the adapter. The M6 holes are counterbored so that the hub can lie flush to the plate.
All of the components, less the blades, are assembled prior to fastening to motor.
The first step is to insert the M8 bolts from the front and then mount the adapter to the motor using the M6 socket head cap screws.
The pitch of the blades is set and the propeller is mounted with all fasteners torqued per spec.
Carbon fiber goodness.
A view looking aft. Next step is a prop run-up.

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