Motor and Propeller
Based on the required power on the propeller shaft, several iterations have been made in order to select the best motor for our application. Both the DC and DC Brushless (BLDC) technologies were considered. There are two criteria in our case; the motor has to be able to give a high power for the take-off, but more important it needs to have a very high efficiency at low power, when the airplane is achieving level flight what is the major part of the time.
Finally, a MAXON DC, RE-MAX 29 (161g) was selected. The motor is well suited for long-term operation thanks to its graphite brushes and the selected optimal operating point, far from the short-term operation. A gear with a reduction ratio of 8,1:1 is connected to the motor.The propeller is composed of two 60 [cm] diameter blades with a Goe795 profile.
So far, the wasn't any commercial brushless motor suitable for our application, because they are all optimized for high thrust, but not necessarily for high efficiency at low power. But we are currently working with brushless manufacturers in order to improve this.