2 m/s on the upstroke and 6 m/s on the downstroke.
If you simulate this you see the difference in speed would be higher in light winds and less in stronger winds.
Also using «anti-gravity» ensures a more constant flying speed in spite of gravity forces, which again may have positive consequences on the difficulty of properly controlling the kite.
OK thanks for that explanation. One thing I notice is it seems that the relative windspeed increases on the upstroke, although it is due to the kite traveling partially upwind on the upstroke due to the angle of travel. It seems like the pulling force would be highest in the upswing too, although power would still be proportional to reel-out speed x this force. If the aircraft weighed nothing, how might that affect this approach?
If the kite is flying at constant speed then the tether tension is fairly constant. So there is less power to the winch in the ground in the upstroke because the reel out speed is less while tension is the same.
You can imagine smoothing of operations by investing power in the upstroke that will be returned seconds later in the downstroke in a ratio more or less 1:1.
The prop/turbine thrust comes into play because you can only play so much with the winch speed. But it adds cost and mass to the kite. So there is probably a sweet spot if you should try this maybe 30-50% thrust from props [makani] and 30-50 % by the winch, and then accepting thay full anti gravity compensation is a matter of diminishing returns.
The patent is not written to be easy [or hard for that matter] to digest. There are conventions to be followed, and more focus on covering options than providing a clear explanation. I may present this in a youtube video or a conference later. Its still a bit soon. In such a presentation the concept would hopefully be more digestable for outsiders
Thanks for explaining, Tallak. I agree that, given the limitations of the kite-reeling concept as currently pursued, that is a reasonable, and, as you say, almost necessary or even obvious band-aid, for those who have experienced this gravity and direction-of-flight issue. The problem, as I see it, is we’re now up to two (2) major sources of unsteady output (besides the intermittency of the wind itself, which adds a third source of unsteady output) with each source of intermittency requiring an energy storage band-aid. Regular wind energy requires only one (1) band-aid - the intermittency of the wind itself requires either a large, forgiving grid, or storage. It all adds a lot of “All ya gotta do is…” complication.
Meanwhile, I would say, it would be easily possible to explain the basic concept in one or two sentences placed in the patent;s front-page summary section. That is what the front page summary section is for - to save people from having to wade through page after page of descriptions of the problem to be solved, until the reader gives up and moves on. 