As mentioned in the post related to the Moki 250 gear reducer (RG250), I'll briefly describe you here our second project, a quarter scale Hamilton type propeller equiped with an electrical stepper motor (or equivalent) moving a mechanism to adjust in flight the pitch.
Electrical supply of the motor will be in the form of an electrical rotational contact located right behind the hub.
It's a subject which was thought since a long time.
The 3D printing is almost on the way.
The blades (38" diameter for the prototype) will consist in a modified wood propeller from a standard 3 blades propeller (FIALA).
Of course we have a big work on the regulation system but in a first step it will probably be a kind of a "3 flight modes" system by the use of a 3 positions switch on the transmitter.
1) Fine pitch (take-off/landing)
2) Medium pitch (normal flight)
3) Coarse pitch (high speed)
The mecanism will not allow unwanted blades positions such as 0 pitch (feathered - something that could be modified for a twin engine aircraft...) or very high pitch (nice airbrake !).
Later on, we could think about a regulation depending of the aircarft speed and the engine rotational speed which approach this system to a constant speed prop...
A two blades and four blades prop system is conceivable but let's build and test the three blades first...
Here is the first rendering:
This prop could be mounted on any engine but the power (and more the torque) has to be adapted.
Link to the french forum:
http://www.modelisme.com/forum/aero-pti ... n-vol.html
Note: Maximum rotational speed has still to be determined as the centrifugal force increases with the square of the engine rotational speed.
Regards,
Sebastien