Probably because "stiffness" to you means how far the LE can be deflected/bent before it buckles ( inner edge wrinkles or folds over ).
Right, I can definitely see how the amount of elasticity of the material especially on the back side of the bend would allow more or less bending especially considering the whole length of an le.GregK wrote: ↑Mon Oct 18, 2021 4:19 amProbably because "stiffness" to you means how far the LE can be deflected/bent before it buckles ( inner edge wrinkles or folds over ).
To an engineer, stiffness is the load/force required to deflect a solid object a unit distance, and it's a function of the object's :
- cross-sectional ( perpendicular to the bending direction ) geometry
- object's material's modulus of elasticity , which is a measures of the material's resistance to being deformed elastically ( and the material property that's improved with Aluula, SLS, or now Airush's Hookipa fabric ).
So where does the kite's inflation pressure enter into it you ask ? If the object is an internally pressurized woven fabric tube, then it's made up of this network of pretty finely woven filaments or threads. Think of them as tiny ropes, and bear in mind that a rope can only support tension - you can pull on it, but you can't push or compress it. When you bend an object, let's say downward at the ends, about the top half of the object is in tension, and the lower half is in compression. And it's the internal pressure that is keeping the lower half in tension.
When a kite's LE buckles or folds, the compression from bending exceeds the tension from the inflation pressure, and like trying to push a rope, it folds up.
Clear as mud now, right ? Don't be discouraged, kite LE stiffness is complex. There's also an additional stiffening effect of the internal pressure I've omitted. Or if you are liking the above, just ask for more, and we'll go another round.
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