From a commenter under the video:
Summarized the measurements, with rough timestamps:
Stock blades (6:43): 1 m/s, 64.3 W,
simple airfoil (7:55): 0.8 m/s, 66 W
modern airfoil (9:12): 1.2 m/s, 64.5 W
stock motor no blades (13:49): 53.8 W
BLDC motor no blades (16:24): 8 W
BLDC stock blades (18:27): 1.8 m/s, 59 W
BLDC stock blades at reduced speed (19:35): 1.0 m/s, 27.3 W
Thanks for the summary, wish he would have had that during the vid
Interesting video, thanks for tabulating the data
I’m surprised he is measuring with the fan so close to the ground, with the electronics obstructing the fan downwash, with the anemometer so close to the fan, with the anemometer so close to the edge of the fan, and with the anemometer so irrepeatably placed…
I don’t think he has accurately measured the efficiency of the induction motor (no load -> stock blades @ 1 m/s is a power change of 10.5 induction and 19.3 for bldc). He is pretty casual in his dismissal of the cost premium of bldc motors too.
I love the intro explaining that sweet spot between something you are interested in and something everyone is talking about. Great video!
BLDC motors, also called brushless, is the silent geeky revolution that brought us lighter, cheaper and more efficient robotics. It also allowed to make battery-powered electric version of many gardening equipment. More precisely, it is the design of cheap lighter controllers that made all of this possible (a good controller will require a fast-ish microcontroller on board)
Kind of a niche subject but happy to see it here!
the video fails to consider the effects of angle of attack on efficiency. Ideally, they would isolate the motor from the fan and measure the power in the shaft, using a torque sensor and some angular velocity data. That way, they can find an efficient fan blade and its optimal speeds separately from motor efficiency.
