Originally Posted by RONALDO_UK
Great explanation DennyV and thank you.
But HOW did you know I had a Piper Cub??! Several in fact and I'm counting my Champ as one too. They're mainly off the shelf but one, which I believe was built by an experienced modeller, is tissue and balsa, about 36" wingspan. It's fitted with a 1700kv 55W brushless motor, a 10A ESC and a GWS 8x6 hyper drive prop. He recommended a 2S 500mah lipo - I've yet to fly it (inexperience and cowardice!).
By the way, I presume I was at least right in saying the ESC controls the current (amps) delivered to the motor (must do, it certainly doesn't control the voltage)?
I dread to think how much time you spend on this site? - you've certainly helped me on a few occasions and I'm sure many others. That's what I call passion for your hobby!
LOL, as for the Piper Cub, I didn't
And, the maximum current and maximum watts that can be pulled by the motor is controlled by the motor specifications, the propeller size, and the battery and its voltage. That is the power output you will get when the ESC gets a "Full throttle" command from the receiver.
The receiver sends a train of voltage pulses to the ESC (and all servos for that matter) where the pulse width varies from one millisecond at low throttle to two milliseconds at full throttle. The ESC takes that one millisecond pulse, and translates it to zero power to the motor, and takes that two ms, and translates it to full power.
At pulse widths between the one and two millisecond wide pulses, the ESC "Chops" the power to the motor at a very high rate, like 10 or 20 thousand times a second. If you've got good hearing, you might be able to hear this switching take place from the motor noise. This is what is called PWM, or pulse width modulation. The ESC controls all this stuff with a little computer chip microcontroller. Those microcontrollers are found everywhere, like a bunch of them in your automobile, digital control for the microwave, digital watches and clocks, cell phones, dishwashers, you name it. You can buy those little chips nowdays for under a dollar.
Times have really changed over the years.