So, kv relates to motor speed, or as commonly known in scientific terms ‘motor velocity constant.’ In simpler terms, it is a way to measure the speed of a motor in relation to the voltage you supply it with. The K in kv represents revolutions per minute (rpm), while the V stands for volts, which tells us how any times per minute the motor will spin when you apply 1 volt with no load. This is theoretical, especially because in the real world factors such as load of simply turning the motor however gives a pretty reasonable representation of how the motor will behave, thereby allowing you to select the right motor to do the right job, which enables you to choose an appropriate matching gear or propeller.
So, what gives a motor its kv value?
Basically, a motor is just coils and magnets aligned in a way that when the current is applied to the coils, they are repelled away from the magnet thus causing the motor to turn. The KV value of a motor is usually defined by the number of turns made on the coils – the fewer the turns, the faster the motor will spin.
How does Kv affect me a human?
The fact is, motors of differing Kv values have different properties that are applicable to different applications. Generally speaking, a high Kv motor is normally used to turn a tiny load very quickly, whereas a low Kv motor turns a larger load mor slowly. What’s more, low Kv/big prop combination produces more torque, which in turn helps in moving heavy craft, whereas the high Kv/small prop combination is the exact opposite: meaning that it’s best suited for overcoming the air-speed differences once the craft is moving.
Due to these different properties, you will find that low kv motors are mostly the ones used for heavy wing craft and multi-rotors, since they don’t have any glinding ability. On the other hand, high Kv motors are best suited to EDF’s, pusher models with smaller props. Now, the normal flight battery voltage plays a big part when choosing a motor that has the right Kv rating; for instance, a 2s setup running o 2000 Kv motor will be approximately equivalent to running 1 motor with 1000 Kv on a 4s setup.