From the abstract:
The aircraft have wingspans of approximately 60 m and fly large loops of approximately 200 m diameter centred at 200 m altitude.
A simple calculator taking account of velocity and bank angle:
At first glance this seems to fit. But if we consider the wing span (60 m), the inner tip would make a loop of only 80 m diameter. Perhaps also take account of the required minimal speed of a heavy rigid 60 m span wing, knowing that the inner tip will fly slower. So it seems to be a very (too?) tight loop.
Makani indicates a roughly doubled diameter for a similar wing : http://www.energykitesystems.net/FAA/FAAfromMakani.pdf : the circling radius is 265 m, the 5 MW wing span is 65 m, its mass is 9,900 kg.
Apart from that this topic is related to New preprint on large-eddy simulation of airborne wind energy farms.