by Jon Emigh, BME
At first glance, when somebody claims a big leap in the efficiency of an electric motor, it is always suspect - as we all know you do not get something for nothing. When I first considered the CR Flight™ counter rotating prop UAV motor and the claims of huge efficiency leaps, I was skeptical at best. We set up the test bed, ran the tests and I realized that I was not looking at an increase in motor efficiency, but
"Theoretically you could get twice the work out of the motor."
rather an increase in process efficiency. Most motors are judged on efficiencyon what usable horsepower they put out for the number of watts that they are using. You bolt a motor to a test bench, place a load on it and verify the wattage used.
Unfortunately this does not go far enough in the process. When you load the motor down, the force of the reaction is absorbed by the bench. We are all familiar with the term, for every action there is an opposite and equal reaction. Since the motor has to be mounted in order to pull work out of it, the evaluation stops there. What would happen if you could use the energy being absorbed by the bench fully? Theoretically you could get twice the work out of the motor.
Instead of designing the motor with a rigid mount, the CR motor™ is connected to the multi-rotor with a rigid slip ring that allows the motor to fully use the energy generated by both the active and reactive force in the motor. The propeller spins in the direction of the motor, while the opposite propeller spins with the motor housing utilizing the reactive force. This drops the speed of the front propeller to half speed and engages the back propeller to half.
"The innovative design can drastically increase range, life, payload and duration of a UAV platform"
When looking at the CR motors™, don’t think motor efficiency gain, but instead look at process efficiency gain. The innovative design can drastically increase range, life, payload and duration of a UAV platform, while eliminating almost all reactive forces sustained by the drone structure. This will allow for a much lighter frame required for mounting the motors as you have no reactive torque to deal with. Their process efficiency cuts the power drain drastically for equal thrust or increases the usable thrust drastically for the same power usage, depending on the requirements of the application.
There is a jump in process performance efficiency. CR motors™ run up to 49% cooler compared to a standard motor
Reduction in Operating Temperature
The value added for a drone manufacturer and their customers is both significant and quantifiable as well as making a significant technological boost to the unmanned aircraft themselves.