Just an update. IMHO high flying kites are generally more useful than downwind kites. So I am interested in L/D and such. I measured this the other day.
I added a hollow tail to calm down left-right motion.
67 degrees should mean a L/D ratio of 2.4. I believe this is quite good for a Pilot type kite, in particular one that flies in very little wind and pulls like nothing else.
High wind needs to be solved for this kite though