calculating RPM at max torque

[michael503]

I have a Trex 450 with a Hacker motor and wish to adapt a variant to this motor. Most of the specs I understand, but where does one get the figure for Engine RPM at max torque?

[seaky]

Hi,
If you know efficiency and Kv of your motor you can calculate approx. rpm
http://dhrc.rchomepage.com/calc.htm

or just use this formula: NominalLiPoVoltage * Kv * Eff
example: 11.1 * 3800 * 0,9 = 37962 RPM

Accurate engine RPM at max troque might be on specification of your motor.

Regards,
seaky

[Pinecone]

Electric motors don't work that way. Max torque for an electric is normally 0 RPM.

Electric make torque based on load up to the limiting current. And actually roque goes down as RPM raises.

This is why trains are deisel electric, the electric motors actually drive the train so they can deliver massive torque at 0 - low RPM to get a 100+ car freight train moving.

One current magazine has an article on this. Fly R/C maybe.