I've given my KFm4 f22 a fly about.. This model no problem..
I was trying to do some speed runs to record the doppler effect and check it on my android phone.. rcspeedo is the app..
phone app measured speed at 22-25 1/2power and 30-40 full power..my guesstimate was about the same, its not my fastest model
runs measurement seem to go up and down, is this due to flying with and then against the wind on the runs, I wonder..