V-Prop

The main spinner is fixed to the output shaft in the normal fashion; but the vaned spinner is free to contra-rotate, and in doing so both generates its own power and derives rpm data that it uses to determine the ideal blade angle.

On the ground, the electronic control system can be tailored to suit each aircraft by varying some soldered connections, which give some 16 options.

Hoffman Propeller plans to develop the V-Prop for fitment to certified aircraft as well as to kit planes.

Although the original 5kg two-bladed propeller was effective and was fitted to several European ultralights, Hoffman have suspended any further development.

Instead, Hoffmann are focusing on the more lucrative certified aircraft market, and their current prototype is a five-fold heavier (25kg) three-bladed propeller for engines such as the Lycoming O-360.

The V-Prop is an automatic self-powering electronic variable-pitch propeller developed by Silence Aircraft. A contra-rotating vaned spinner ahead of the main spinner both powers a microprocessor and delivers data to instruct the blades to be adjusted automatically.