Parafoil kite out of control... what to do?

Hello,

I have a parafoil kite that is pretty close to this one:
http://www.intothewind.com/cgi-bin/detail.cgi? itemnum=5195&sql=air

Almost every time I have flown it, it seems to want to go in circles rather than fly straight. In a good breeze it will sometimes do a circle. I can get control of it a bit if I let out line or run towards the kite... but, I would rather it just fly straight. I have a drogue chute on it, but wonder if I need something more serious to keep it stable? Perhaps a longer line with bigger drogue chute? Any ideas?

BTW drogues add stability by increasing total drag and making it harder for the kite to pinwheel. A drogue on a single line could contribute to the problem if it flies back and forth or twists.

The drogue also tends to lift the bottom of the kite, lowering the angle of attack as the wind increases. This also contributes to stability, but would work better if the tow point were movable - not the case in that kite.

Use two lines on the drogue for maximum stability and use a swivel.

The kite behaves when you reduce the power on it by letting out line. By the sounds of things its pretty close to stable but just needs tuning a bit. Try flying on less windy days? Try a bigger drogue or more tail. Next option is to move the tow point back a little bit. Is there any option ot adjust the tow point on the flares? Unlikely, so the drogue tail solution may be the only one available to you.

Assuming it is made symmetrically it should fly reasonably straight. All cells look the same and inflate equally . . .

The bridal lines have to be the same lengths (of course).

How is the drogue connected to the kite? They mention three attachment points - a drogue is best when flying from two lines ~2-4 times longer (experiment a little there) than the kite is wide and with a swivel.

One assumes you aren't trying to fly it in a gale . . . How windy is a 'good breeze?' Above ~20 kts it would probably be a little touchy, if that's the case add more (balanced) drag to the tail (larger or multiple drogues) If your drogue is open at the end, you'd have to add some attachment points (3-4) for the next drogue, if it has a mesh bottom, a fishing snap swivel is a quick and easy way to connect. The second drogue has to fill with air so it needs to be far enough back from the first to encounter some clean air.

Imbalance in the bridle?

Best, Stephen

Remove footfrommouth to reply

Small parafoils are often unstable. The one in the picture was a 15 to 17 sq ft. That is 'sorta' small (but at least it is not a 10 or even a 5 sq ft!)

The first think I would do is add a long tail. Often 'drogue' tails that come with some kites are not up to providing enough drag to stabilize the kite. It will be easier to add a long tail then mess around adjusting the bridle (and you can make things worse doing that) Also, any kite has a wind range that it will fly in. Below the 'wind range' and (of course) the kite will not fly (not enough wind), but *above* the wind range the kite will not fly because it will be unstable. If you are trying to fly at the top end of the range it may exibit the symptoms you see.