What is the meaning and kV value of the model brushless motor for model aircraft

With the increasing number of friends who love model airplanes, model airplane knowledge has become a hot topic of discussion for many friends, such as the meaning of model airplane brushless motor models and what the KV value is. Let's analyze it below!
 

Taking model aircraft motors as an example, brushless motors for model aircraft can be roughly divided into three series:

1. A series, internal rotor slot brushless motor, stator winding slot type silicon steel sheet, rotor magnet rotates inside the motor.

2. B series, internal rotor brushless motor, stator winding silicon steel sheet without slot, rotor magnet rotates inside the motor.

3. C series, brushless motor with outer rotor. The stator is a frame composed of windings and silicon steel sheets, and the rotor magnet rotates outside the motor.

The motor manual generally indicates the shaft diameter of the motor spindle, which can be 2.13mm, 3.17mm, 5mm, etc. Before purchasing a model aircraft motor, the appropriate model aircraft motor should be selected based on the requirements of the motor shaft diameter and external dimensions.

In general, the manual of B-series motors will have some special markings added by the manufacturer, such as bl3674/8. The outer diameter of the motor is 36mm, and the length of the magnet or housing is 74mm. 8 indicates that the coil winding consists of 8 turns. BL indicates that the inner rotor is an extended brushless motor. If it is BH, there are two meanings, one is high-voltage brushless internal rotor motor, and the other is extended internal rotor brushless motor.

Model aircraft brushless motor type KV value:

The KV value of a brushless motor is defined as speed/V, which means that when the input voltage increases by 1V, the idle speed (R/min) of the brushless motor increases. According to this definition, the voltage and idle speed of the motor follow a strict linear proportional relationship and are constant. Regardless of where the motor operates, the relationship between voltage and speed follows this value.