[Mike Betts]

Originally Posted by colin340

after looking at the graphs for the thousand time I sort of understand how to read them I see that maximum efficiency at 88 RPMs

I had the idea about Max torque at zero RPMs from electric dragsters
But I guess that doesn't translate maybe brushless motors?
Anyhow I'll gear it to hopefully bog to 88 RPMs
Thanks for all help folks just goes to show 20 years of school rarely matches up to simply asking a question and accepting that you are clueless in the subject.

ps Wankel's are awesome i Have a snowmobile with one

Colin,

You are confusing power and torque. Your statement about maximum torque at zero speed is absolutely correct. However, power is equal to torque multiplied by angular speed. Since the speed is zero at max torque, the power is zero hence the efficiency is zero.

This is why you will read about these motors burning out is you stall them at full voltage.

At the other end of the curve, the torque is zero at "free speed" and, once again, the power is zero.

For DC brushed motors, the max mechanical power is always very near 50% torque and speed (exactly 50% in a perfect, theoretical world). The max efficiency will always be at a lower torque (higher speed). Exactly how mush lower is the question...

20 years was not wasted. The laws of physics still hold and all is good...

Regards,

Mike