Crosswind paths allowing to use a larger powerkite for a same tether length

[PierreB]

In figure-eight or circular path the kite uses only a small part of the frontal airspace wind. This topic is intended to study trajectories that optimize the space by sweeping the largest possible wind area. Below is a thought about U-turn with zero radius allowing using a larger kite for the same tether length.

Reversible kite

As a reversible kite likely leads to a loss of power, perhaps using a classical power kite could allow using not more space by making U-turn with zero radius, like on 0:31 of the video below: [Kite flying backwards] If U-turn with zero radius can be executed with huge power kites, this can allow them to scale up more. In yo-yo configuration the reel-in phases occur during U-turn when the power is low because of slow motion in the edges of the flight window.

Some other topics were about a specific path such like

Low radius loop

Today I remade the experiment of autorotation with only one other wing then I obtained the same result as on the following video I put again: 4-5 kg regular traction measured with a steelyard on the line taut with 4 m/s wind speed while I obtained 3 kg surge traction in crosswind larger figure-eight and for one of the two lines, the other line giving a lower value in the same time, and the total value being irregular and probably lesser. So it looks like an autorotation with low radius loop …

or

Vertical trajectory for yo-yo AWES?

It is true and may be ute ultimate expression of super short tether AWE. You could probably make a kite to fly up and down well (without resorting to making the kite a «bag»). Going down should make less/no power. There is a slight issue with flying up/down, and I would rather go right/left. This is to deal with gravity. When going up, you can’t easily point the lift force upwards to compensate for gravity. Doing this will change the angle of attack. If you are flying left/right, this is just …

The present topic is about all possible ways to achieve its purpose.

I put again some elements for a first approximation of the kite area/swept frontal airspace wind, so something equivalent to the solidity in current wind turbines.
The Power Harvesting Factor ζ is described on the pages 15 and 16 on:

Diehl2013a.pdf

The solidity can be roughly deduced from the Power Harvesting Factor ζ.
Solidity = 1/(Power Harvesting Factor ζ x 27/16). Some examples:
ζ = 5.5 for a wind turbine, solidity = 1/9.28);
ζ = 8 for Makani, L/D ratio = 7.35 with tether, solidity = 1/13.5;
ζ = 30 for a rigid kite with L/D ratio = 14.2, solidity = 1/51.
ζ = 4 for a flexible kite with L/D ratio = 5.2, solidity = 1/6.75;
ζ = 2.37 for a flexible kite with L/D ratio = 4, solidity = 1/4;

So a flexible (possibly networked) huge kite of ζ = 2.37 and solidity = 1/4 would be a reasonable start. The flight window could be maximized for different sorts of single kites.