Testing my rapid prototyped propeller
470 views · Published 23 July 2010 · 0:30 · Indexed 11 October 2026
Channel: Paul Nathan · 2010 · Science & Technology
Here is a quick video showing the first test of a rapid protoptyped (SLA method at 50micron resolution, done by IDC modelling in Datchet, UK - great little company and staff) propeller designed using an algorithm I wrote. This video is more eye and ear candy than anything technical! The background is not my house!! The propeller was designed based on the inputs of design point shaft power, RPM, tip and root diameter, forward travelling speed and single aerofoil section with associated lift / drag polars. The propeller is optimised for maximum efficiency, and also for having a constant spanwise circulation distribution. I did not use the Goldstein circulation function. If you want to know more about how to design a propeller blade, feel free to ask. This is the most basic propeller, tip / hub losses were not accounted for (but compressibilty effects were). The tips travel at Mach 0.31 and the air flowing over the tips travels at Mach 0.7 - not supersonic (and I didn't want that either!). Equipment: Motor: Brushless DC E-flite Park 400 740Kv Speed controller: Etronix 25A Receiver: Planetside R6M Battery: 11.1V 2700mAh Li-Po Propeller spec: Power: 80W RPM: 8200 Torque: 0.093Nm Rhub: 0.03m Rtip: 0.13m Advance speed: 0m/s (static lift application) Propeller predicted performance: Thrust: 7.91N Power loss to drag: 14.08W (17.6% - bah!) mass flow rate: 0.49kg/s Tip Mach No.: 0.319 Pressure ratio: 1.072 Centrifugal force on blade-hub connection: 97.76N (if only that was the thrust!!) Aerofoil cross section used: NACA 4410 Root chord: 0.04m Root twist: 26.56deg Tip chord: 0.0074m Tip twist: 10.92deg Reynolds number (avg.): 55400 (rather low, so natural transition via laminar bubble, however the external disturbance by sound pressure waves probably induces bypass transition). The lift / drag polars were computed using X-foil 6.96 by Prof. Mark Drela from MIT
