Hi:

I am trying to understand how exactly a brushless motor works with apropeller gearbox and battery packs. I have never done this before.

I have a Hacker B50 S13, I know the kv, kt, and Rm.
I have 16 battery cells GP 1100 (1.1 Ah, 1.2 V)

1. I need to know the equation to find the current (Iin) to the motor,so I can find the torque.

2. I need to understand how the gearbox works, and how it affects the pitch speed, etc. What equation do I use for that?
the Hacker B50 motor is equipped with a 6.7:1 gear ratio.

3. How do I calculate static thrust and in-flight thrust? I now that Power output = thrust * pitch speed = torque * RPM, but what thrust is that?

In short, i need to know the mathematics of electric motors.

Please, any help would be greatly appreciated.

carpediem85.

The simplest approach is to play around with the numbers using this on-line motor calculator:

[link=http://brantuas.com/ezcalc/dma1.asp]http://brantuas.com/ezcalc/dma1.asp[/link]

/Red B.

Yeah I have been playing with it. hehehe

Basically, I need to write my own motor calculator, so I need to know the necessary equations. I have tried to find them online, and I have found some, but not all of them. It's getting frustrating, because I must have those equations asap...dateline approaching..

Measure the current with a multimeter. Most have a place to connect the leads to do this.
All you do is put the meter in series with one of the battery leads supplying the power to the motor.
You'll have a startup current and a run current. Use the run current for your calculations.

You may want to post this question in the electrics forum, they're are some real Gurus over there.