Because they can’t be inflated by fan, require more bridle lines (presumably), design window is a lot smaller as a single skin kite will easily buckle, etc.
Like I say, single skins are very interesting, but they are at a more advanced level, construction and handling wise. Also to this date I am not aware of really large single skins with higher lift to drag, big wind range, gust handling etc.
The closest we have are probably Flysurfer Peak and similar kites, which actually have many other design elements compared to a normal twin skin paraglider style design.
The comparison is really gross if you compare single skin kites to LEI. LEI’s are produced at much lower cost to foil kites, simpler design, more precise control of performance etc. It should be clear single skin kite is kind of a non-starter these days for any project wanting to produce electricity, because the single skin technology would have to be developed first, and many talented people have struggled their whole life doing only that.
To be very specific, I don’t think Afrokite is a huge step in the direction of developing a single skin kite at huge scale, with handling and higher aerodynamical efficiency.
Parachutes causing drag is of course a different matter, but I am still thinking about more mainstream AWE concepts here (hovering/bounding with crosswind flight)
However a NPW like Windsled 2:18 is until 150 m². The lift to drag ratio is not high (about 2.5-3), leading to half the efficiency of good double-skin foil kites. But this can be compensated by the ability to turn tighter. Finally, if we can make an NPW kite of 150 m², perhaps much larger dimensions are possible: it will be seen. NPW are cheap.
The flight window is small, which can be an advantage for a denser kite farm whose flight spaces are limited before the intervention of the control systems. Combined with tight turns, the small flight window in the most efficient center part, could allow to better maximize the space compared to more efficient foil kites using more space for their figures, not to mention the very efficient rigid wings but which must use even more space, always in relation to the useful space for wind power really harnessed compared to the area of the figure.
Im not sure. The goodness factor is a property of the system. You could choose to say kite choice is a parameter to the design and then also this number, but in reality you cant choose many different options. The «goodness» number is just pseudoscience I would say, but it’s a nice indicator for a kite, in the kind of systems one normally associates with AWE (crosswind flight systems)