“The result, as can be seen from the picture below has the dimensions of the wing of a large airliner but is lightweight and semi-rigid. The wing is formed by 9 ashlars hinged together by flexible joints, thanks to which it can easily change configuration in order to vary the wing lift factor.” http://www.kitegen.com/en/2014/09/12/kitegen-power-wing/
A scientific publication is on
“We observed a slight deterioration of the over-all aerodynamic performances of the curved wing (non-tethered kite) with respect to the flat configuration.”
The expected advantage is eliminating the cantilever effect of a flat wing, allowing saving mass, keeping a still high L/D ratio.
From kitesurfing we know that anything more than 20 sq meter size flies very slowly, and is increasingly difficult to keep airborne in low winds.
A C kite has its origin of roll rotation far below the CG, and thus is quite opposite to a rigid wing’s origin of roll directly beneath (or ideally at) CG (center of gravity). Being anhedral, when it turns, there will be lifting forces generated on the outer side of the wing causing roll away from the centerline (the line around which you are looping). This causes drag and also an undesired force in centrifugal direction. So the wing is bound to sidelip through the air causing excess forces on the inner tip.
Its not a showstopper, but not a good starting point for AWE imho.
Anyways, it might still be a viable option for AWE. The C kite is super lightweight and easily built, so a design accounting for above effects could well work. With the low weight, perhaps sentrifugal forces are not so important?
Just for the record: I’m not just being negative about anhedral with no other option, you can have a dihedral wing if you have a supporting bridle, or some other way…
Another link and @Massimo’s comment (of which an extract below) on
“All 5000 wings weight just 1000 tons and cost approximately 300M€/year as consumable.”,
so 200 kg per wing, compared to 2 or 3 tons for a flat wing for a similar MW-range power.
