Test it
Getting the angle of attack (AoA) right is critical. Too low AoA and the kite will have a very small window of flight (wont go high in the sky and if buggying you wont be able to make any way tacking into the wind).
Too high AoA and the kite will go very fast with little power right up above your hear and collapse at the apex and probably flutter down on your head...
The correct angle is hard to calculate for a new design since it depends lots of factors (drag of bridle, airfoil shape and lift, number of bridle lines and their thickness etc.
My 2m high wind kite is bridled with sheathed dyneema on every cell and is set at about 12% (ie primary birdles join at 12% back from the leading edge) where as the 8m kite is bridled on alternate cells and is set at 25%. Foilmaker sets the default to 18% which is a good starting point in the absence of any other information.
I took to marking 12%, 18% and 24% in 3 different colours to make it easy to adjust the bride if necessary. Depending on the geometry of the design
generally it is only the first (A) and third (C) bridle lines that need
adjusting. Just get foilmaker to print the bridle line page for the angles you think might be useful.
Notice that the difference between 12% and 24% is only a few cm at most. -and the kite probably will be unflyable at the wrong end of the range ! However it is very satisfying once you get it right and it flies right up to almost 90 degrees above the gound and stays there !
The result
So this is the important bit - how does it fly ? These pictures were taken on a day with virtually no wind at all (my thanks to the unsuspecting passer-by who had a camera thrust into his hand...) In a light breeze (5-10Mph) this kite has proven to VERY powerful. It is also reasonably fast also. Bridled as it is, it is possible to make it overfly the edge of the window if the wind veers suddenly, but it collapses slowly and a sharp tug will have it inflated again.
Of course an advantage of foilmaker is the ability to simply change the area and scale the whole kite down. I have a 4.5m version under construction... Doubtless the bridle angles will be slightly different though.
Loads of power in 4mph light air
right: I need a digital camera with zoom lens !
right: virtually no wind here causes slight distortion in the turn. I was trying to avoid hitting the camera person...
almost directly overhead - and very stable.
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Last updated 28 April 2002 by
nns@aber.ac.uk