Luffing is not a bad thing you know. A kite, like any wing is a foil shape for aerodynamics. The fuller the foil & the less sheeted(depowered) the more it is prone to luffing. The alternative to luffing is backwinding, resulting in the kite tumbling out of the sky. The Slingshot Link was the classic example. 9 struts, a stable & rigid foil, as well as being heavy it was prone to tumbling, no matter what the wind strength.
Col

Angle of Attack = 0 ...?

^ ^ ^ + 1 Kamikuza & Eppo

From a sailing perspective.... it is a supported sail becoming back winded, going to close to the wind direction UPWIND. i.e. tacking through the direction of the wind.

"Luffing" or back winding is when the trimmed structure (main/jib or other sail) points with the vessel to close to the wind. Simple example tacking from port to starboard "bow through the wind".

For kiting, fold the bit of the canopy closest to the inflated leading edge towards you, making like an "S-shape" of the wing, then lose pull on the lines and kite falls out of the sky.

It could be created by accelerating the kite across the power zone in the wind window to the edge then to "go to far' and the wind gets on the other side and it falls out of the sky & towards you on the other tack. As a kites' leading edge would rarely if ever act like a forestay on a sailing boat with a mast, the luffing effect is rare, undesired and seen perhaps as poor flying (poor AoA for flight, no Lift, no control = fall of kite & Oh S**t, care of power zone).

Before u bring out ur own brand eppo, throw this page some thought

www.aerospaceweb.org/question/aerodynamics/q0228.shtml

Cheers Gorgo.