[Mister-T]

The brushless have more torque than brushed for 2 reasons :
- Even you have smaller permanent magnet (with theoricaly less magnetic field), the rotor is mush more lighter than a brushed rotor (iron and copper are heavy)
- In RC car the brushless has the autorization to use Neodymium Magnet when brushed simply use Ferrite magnet (the rules are dicted by two manufacturer for ROAR and EFRA... There was a time where dragsters used brushed motor with Neodymium magnet)

The other interest about brushless is the reliability, no comutator, no brush. Less maintenance time = more time to fun.

Sensor or not Sensor ?
The Sensored have better startup (I don't speak about torque) but in high end RPM the Sensorless is faster (because of control loop feedback that take time in sensored case)


For concluding Brushless motor Let summarize :
- Theorical like the brushed
- Linear relation between RPM and voltage
- There are no speed limit due to Foucault currents but speed limit due to the controller and battery ability to drive/generate high current drain.
- They have more torque due to their Neodymium Magnet
- The torque is given at low RPM (Y-wound) or high RPM (Delta wound)
- The sensor will give a bonus when you start a round (the best way I think is to not use sensor when the motor reach 2000 RPM)

IV)timming
I put this in other chapter because it's aviable on every motor (even sensorless).
In the motor (brushed or brushless) the magnetic field of one coil is changed (its current goes through 0) when the coil is perpendicular to North-South line of the permanent magnet (either stator or rotor)
The main Idea is to apply the change of the magnetic field of coil before this event, by this technique you delay the Foucault current in a little high RPM.
The Timing angle can vary from -45° (useless) to 45° but it's pratical impossible to put so much timing angle. When you put timing angle keep in mind that your coil will switch when it's in a field of permanent magnet. A coil became a generator a send current in normaly input that will heat up either controller (brushed or brushless) and the motor.
To my mind there are a stock class in US (around mid 90's) that work with 36° timing stock motor.
With current stock motor it's not a really good idea to do that (17T in France).


V)Future
Just one word about a kind of brushless called outrunner, the rotor (with permanent magnet) is outside and rotate aroud the stator.
The idea behind is to give more torque due to the bigger moment the permanent magnet give (permanent magnet is one key of torque)
Already used in Air model, not in car model (you can even find some for your car but not legal ROAR or EFRA) They are probably also too dangerous for marshal turn (they don't have "encapsuled" rotor).

To our future engineer, the R/D on electrical motor are not finish there are a lot of dark part that no one can explain.

I hope you enjoy this explain, I try to not put equation, because I'm not good to resolve mathematics, but I bet the main electrical motor concept are here.[/QUOTE]