I was probably wrong as the Induction factor is very important for secondary rotors for fly-gen AWES.
A current wind turbine has a thrust coefficient (table 8) of 0.9 at Betz limit. For my initial estimates, I rounded to 1.
So the wing area is 1 m², the lift coefficient (CL) is 1, the drag coefficient (CD) is 0.25, L/D ratio = 4, coefficient cosine³ = 0.65, air density = 1.2, wind speed = 10 m/s. Power: 924 W. The secondary rotor had a CD value of 1, with an “optimal” swept area of 0.125 m², the rotor thrust adding 50% drag to the kite-tether drag as usual.
But I remarked that the rotors of Makani M600 and other fly-gen AWES looked (for me) largely oversized. A main reason is to lower induction factor in order to obtain a better efficiency in regard to the kite potential.
To keep the proportions my initial rotor of 0.125 m² should be about 6 times larger, so 0.75 m², in order to maximize efficiency by lower induction factor.
Note that a static turbine of 0.75 m² with a CP of 0.5 would produce 225 W, so only 4 times less, compared to about 100 times less when used with well sized rigid wings.