SSSL  Sled

From 2014, various attempts were made at developing SSSLs with no bridles to the body, all bridles being to the sides.  Some are pure sleds (one an Arc sled with just 4 bridles), but most have bridle supported leading edges.

An inherent problem is that side keels of the constant depth required to support the centre tend to cause a tapered or toe in shape (wider at the TE) which 'hand claps' in stronger winds, and when the keel depth is reduced towards the rear to address this, the disposition of lateral area is still too rearward and causes hanging over in light winds.

Nevertheless, prototypes show some promise, especially for light wind flying and are the open TE SSSLs which require the least bridles so far.   

Stability wise, upper wind limits- their main deficiency, are all caused by buckling which can be addressed by careful panel shaping and adding bridles.  As for SSSL Pilots, buckling causes more problems when to the sides and towards the LE. 

Does scooping of the keels between the bridles reduce buckling or just provide creases that initiate more buckling? 

As for all SSSLs , chordwise and spanwise camber is useful (necessary?) for buckling resistance, but chordwise buckling needs to be minimised to avoid the kite's C of P getting too close to its C of G, reducing the correcting moment.  Having greater camber near the LE pulls the C of P forward.

Various outer TE drag buckets were tried.  They did reduce buckling a lot but seemed to always cause other stability problems (various of the 3 nasties)  Similar experience with SSPs also

Sled 4, Jan '21 10 bridle flies better than  Sled 9, Nov '21 18 bridles, especially after reducing the depth of its centre LE.

Possibly, eventually, LE bridles may be eliminated- they don't stop the LE from folding back anyway, but may have a role in pulling it back out again?