This ring is not round but elongated. Is it to favor gravity allowing the ball bearing falling during each (half) rotation of the kite, a little like on the video below (0:45) but for another use (although for a generator, the mass could be replaced with ball bearings, the tube comprising the coils)?
If yes, a simple tube between the blades could be sufficient. Or even the blades could form the tubes with ball bearings falling by gravity during rotation, passing in front of the coils wound around the tube (s), in a similar way as on the video below.
A large system would work better.
