Amazed the merry band has yet to pick this up
merl wrote:
Interesting. Foilholio's suggestion was intended to cure the "other problem",
I suggest you reread what he wrote. Let me help.
foilholio wrote:
My mod has been used by me. I have used it to fix asymmetric flying, but it also affects clapping
merl wrote:which he suggested would flatten the profile.
More reading. More help?
foilholio wrote:
you are individually altering the camber shape of cells.
merl wrote:
A general question: what is the effect of the flysurfer PMS (?) adjusters? Is it s vertical tension adjuster too?
These alter the shape, or more specifically the camber of the cells, in the same way pleats across the width or span of the cells do.
These may help
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merl wrote:
was intended to cure the "other problem", but it seems it makes it worse.
Rein de Vries wrote:
As the wind was rather gusty today, the other problem, was even more pronounced however.
Rein de Vries wrote:
Some words about the aerodynamics about the solution is also highly appreciated, I would really like to understand why a specific shape change could resolve it.
So I am gathering the whole kite is collapsing? So collapsing is AoA turning negative. So when the tips collapse they increase drag and so the kite will sit deeper in the window. This increases the AoA of the kite and makes the rest less likely to collapse. The primary way a kite changes AoA is position in the window. So by fixing the clapping you have made the kite move more to the edge of the window and so it all can then collapse.
You can also change the AoA by altering the airfoil or the tow point on a kite. By reducing the camber of the airfoil, making the airfoil curve more up, you are causing the airfoil to rotate backwards. This increases the AoA of the airfoil or kite. Think airplane with elevator pointed up, it pitches up. Moving the tow point, or the point where the lines met actually or through combination of multiple lines(bridles) at the kite, changes the AoA. This is because the center of lift, or the point where the pull from the kite acts, is forced to balance against the tow point. If it is not balanced you will see the kite trying to change position in the window.
So to fix any collapsing problem you can alter the airfoil shape, alter the tow point, or alter the drag. To alter the airfoil shape you have already learnt this. By using pleats or other methods like PMAs in or near the top of the airfoil/skin, you can reduce the camber. Think elevator up.
To alter the tow point, you primarily have your 4 lines through the bar. Otherwise you need to move the front line position back. Sometimes you can retension part of the bridles, or there is settings to move some of them. I would think on ARCs maybe the straps can do this, tilting the tip back or forward it will change the tow point.
Drag well you can have part of the kite collapse or flap or even change camber. A simple way to increase drag is to add a streamer. Remember tails on kites as kids?
Another thing is the porosity of a kite. A kite is usually more likely to collapse when the fabric becomes more porous. Arcs are no exception to this and are in fact more dependent on air tightness than highly bridled foils. Likely because they have no bridles. Kites are likely more likely to collapse because their airfoil changes when it is more porous but also because they are less rigid.
Don't despair because you can recoat a kites fabric, to make it airtight again. Shoegoo dissolved in toluene or xylene sprayed onto an inflated kite.
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