Pi*r^2
calculate 1, then 2, then subtract.
Now you have the volume of air moved. Of course there are myriad other factors from magnet efficiency to rigidity to.....
But if all you're asking about is diameter, there you go.
calculate 1, then 2, then subtract.
Now you have the volume of air moved. Of course there are myriad other factors from magnet efficiency to rigidity to.....
But if all you're asking about is diameter, there you go.