I measured (with a multi-meter) 9 volts at 13.7 m/s then 3 amperes at 14.4 m/s, by using a Master Airscrew GF 9x4 on a motor Mabuchi RS-380PH used as generator, at about 7100 rpm, so 85 m/s tip speed and TSR of 6 for an apparent wind of 14 m/s. I extrapolated the 7100 rpm value from the voltage (3.8 volts) obtained with a drill running at 3000 rpm, which is of course very approximate. The apparent wind speed by car was measured with an anemometer.
So about an average of 27 W at 14 m/s, for a swept area of 0.041 m² (diameter of the propeller 0.23 m). At Betz limit the power would be 39.8 W. So 27 W is more than 67% Betz limit, and was obtained with the loaded generator: not too bad for a propeller as wind turbine. I have had slightly or much worse results using other combinations. Of course in all cases the propeller was turned upside down.
In flight on the FlygenKite things are very different because of variations of power according to the place of the kite in the wind window, leading to various significant losses by cosine ³.