foilholio wrote: ↑Thu Apr 26, 2018 2:48 pm
Matteo V wrote: ↑Wed Apr 25, 2018 5:56 pm
And foils have a more rigid structure than inflatables.
Well hmm ok, what can I say? Maybe if your are comparing the non inflated parts of an inflatable to the thicker parts of a foil kite? Honestly though I am dumb founded how you can make that observation. Maybe you can argue it with PMU, or I can quote you to troll him lol.
I claim no authority other than the validity of my argument. I also use both inflatables and foils, though I have no strong bias toward one or the other, outside of their actual strengths. Let me see if I can help you so you can find a weak point in my argument to make a case against. I am happiest when I am shown evidence that I am wrong, as that is how human beings learn. Everything else is "feels", and I am interest in "feels" mostly for how they are counterproductive with respect to understanding reality.
Foil kite:
With the ENTIRE underside of the kite supported by bridal attachment points, from leading edge to trailing edge, a FOIL KITE has more rigidity. Or rather, the bridals that are lightly loaded given their total number, take up all the stretch in the canopy (top and bottom, with connection via the vertical cell walls). This is because the load is taken where it is made at each part of the kite, and transferred vertically to the bridals in close proximity, NOT transferred horizontally a long distance to the leading edge or tips, and then to the bridals. Thus the air foil shape of a foil kite is prevented from warping by those bridals, via the reduction in horizontal forces over the entire canopy. Cord line, camber line, and thickness are all rigidly held in place by having so many bridal lines nearly in line with the forces generated by the foil section. Again, this is likely the reason for the difference in feel of a foil vs an inflatable.
Inflatable kite:
ONLY the leading edge has multiple connection points to the kite in line with the forces generated by the foil section of an INFLATABLE. Steering connection points number only 2 (1 each side, with few exceptions) on most inflatable kites. Thus the canopy behind the leading edge, ALL THE WAY to the trailing edge, is free to warp and stretch according to load limits of the material over the entire span of the kite. The load generated at the center point of the foil section of the kite must be transferred to the leading edge bridals, or the steering lines via the canopy. And the trailing edge is only supported horizontally, not vertically as you approach the horizontal center section (lift producing) part of the trailing edge. Thus forces on the leech line in the trailing edge, that result in pull on the steering lines, are 90° to the resultant load at that particular section.
Think of two garbage bags filled with water:
One rounds out because the water filling it takes the shape of the bag is because the bag is only supported with its outside skin.
The other is an impossible flat bottomed bag, because you have a bunch precise length lines connected to the bottom to support it against "bagging out". Thus you could make a rigidly held (against outward forces, would not stand upright) flat bottom garbage bag with lots of little bridals holding that shape.
Which shape is more rigidly held in place? - Push on the bag without the lines and it will bulge in one direction, then the other, changing it's shape until the wave energy dissipates. But the flat bottomed trash bag will see much less distortion where supported by the lines because those lines limit the movement of the skin.
Many things in kiteboarding, physics, and even life are counter-intuitive. Heck, my view is that most of kiteboarding is learning how to stop yourself from doing what you
think you should be doing.
And thanks for mentioning "Pumpy" - that's all we need here right now.