No need for RPM, this is going on an electric plane. I already have telemetry on my 600N and it works quite well. I'm just wanting another backup for pack voltage so I don't crash the plane when it runs out of juice. I have timers, but I would like to fly until the pack reaches a certain voltage, not just by time. Sometimes I fly hard, sometimes I fly pattern and when you fly pattern, you will not use up the battery as fast. AND, it will warn me if I have a brown out for some reason. And on this plane, the motor is so over powered that it doesn't even get warm, even with the limited airflow it gets in the cowl.