Question regarding KV Values

[Chris0509]

Hallo from Germany,

i need help. The Freewing 80mm EDF what does the KV Range mean 3658 - 1857kv ?

thx

[Twowingtj]

Chris0509 Welcome to Hobby Squawk!
The numbers that you posted, refer to two separate things. The 3658 are the motor dimensions, 36=motor diameter in mm, 58=motor length in mm. The 1857kv refers to the tested rpm per volt of input power from the battery. For example, the 1857kv motor powered by a 6S lipo(22.2v) should turn at 41,225 rpm at full throttle. Item of note, the rated kv of a motor is without the load of an EDF fan or a prop. Hope this helps.

[Chris0509]

Great Thanks, does this mean that higher kv on a 12blade impeller improves thrust? Or other factors driving Performance? Thx 🙏🏼

[Twowingtj]

There are a lot of factors that come into play besides blade count. Like fan pitch near the hub in relation to the pitch near the outer end, stator blade count and angle, and the total rotational mass. Also the shape of the fan shroud, intake and exit ducting size and shape can have an affect on the efficiency in producing thrust. There really is a whole science behind it, if done properly.

[xviper]

Also, the motor being an outrunner or inrunner makes a difference. Given the same kv rating, an inrunner has a better chance of achieving a higher rpm (with the same fan) than an outrunner, hence the inrunner may perform better. We see a lot of the newer re-releases of EDF jets coming with inrunners when they first were introduced with outrunners. The new inrunner versions are called "high performance" versions.