An Engineering Model for Power Generation Estimation of Crosswind Airborne Wind Energy Systems

[PierreB]

@Rodread

The power losses related to the aforementioned phenomena are caused by the roll of the aircraft and its speed variation during motion. The effects of elevation and gravity are relevant and their coupling results to be very penalizing.

I had already mentioned the weight issue of the Makani M600, nullifying a positive production average for a wind speed below about 11-12 m/s (see other videos on https://www.youtube.com/playlist?list=PL7og_3Jqea4VRCZmMNK4LDH64sYgkLZzv):

20190501 CW-08 - Onboard View of Makani M600 During Night Flight [Excerpt]

And also I experienced power losses and speed variation with my old FlygenKite:

- YouTube

I tested the same propellers by car at a similar speed than that of the FlygenKite: the difference looked huge. In the video above you can listen the variation of the sound of the rotor. By car the rotor roars without undergoing any variation, without undergoing any loss by cosine, by gravity, etc. I measured the efficiency of several propellers in the car, some of which had an efficiency close to the Betz limit. Under the wing the same propeller could be transported even more quickly but with very important variations crumbling its output.

Perhaps the AWE field should shift to higher altitude winds as originally, developing stationary AWES aimed at a high elevation angle (impossible in crosswind flight), also allowing more of power density on a farm, using large lifter kite-blimp carrying non-inclined turbine(s) like @Kitewinder.