I've been a fan of first person view drone Racing for years now and, in thinking of building a new quadcopter, I have a question I'm unable to resolve myself.
Please correct me if I'm wrong:
As i understand, a brushless motor has a maximum torque and power (Watts), if you push it beyond its limits it will start heating and eventually burn.
A brushless motor will always try to match the speed required drawing as much amps as is needed so increasing the power used.
Any brushless motor has a Kv value related to the coils windings that determines the rpm it will get without load per volt applied.
Then, can I say, for example, 1000 Kv at 1 volt will be equivalent to 500 Kv at 2 volts in terms of power, rpm and torque? So could I say it will generate the same lift?
Of course more voltage will reduce the amps but that's not related to the question, I think.
If this is true, I can't understand why actual drones do not run on bigger Kv and fewer cells since cells add weight and Kv not.
As a example of my question the DRL RacerX has broke the speed world record using T-motor f80 wich is a 2408 at 2500kv the manufacturer says it should be run at 16V achieving 680W but the 1900kv says 22V around 1000W.
The DRL used it at 42V (the 2500kv version) still with a 5 inch prop (Sure the motor will not survive for a long time), they just seemed to increase the amp rating of the controllers and just hope the motor will last long enought.
Why did they use such a high voltaje (2 x 5s) since that will not only increase the total weight but that will also increase the amps needed (as its increasing the load).
Im sure they had done their research and made the best they could but i want to understand why is that the best way of achieving it, the main question that comes to my mind is why not a larger prop? it should be much more efficient right? and still that drone is for a max speed record maneuverability is not needed