I have a Premier 7.5 parafoil that I use in my Greenland II. This is a standard parafoil, costs around $40, and pulls hard in a strong breeze (up to 20 lbs. of pull) but is lackadaisical in light airs (8 mph). For a pic, see: http://www.gwtw-kites.com/Parafoils.html I was about to get a Premier 15 (around $90), which is said to be capable of lifting small children in the air, when I came across a posting elsewhere from a kayaker who raved about the Sutton Flowform 16. For a description of these kites, see: http://home.snafu.de/thomiru/ff_devel_eng.htm Seda appears to sell the Sutton 8 as their kayaking kite. This sounded good to me, so I ordered up a Sutton 16, also around $90. I flew it in a strong breeze on land (whitecaps on the water). It flew high (higher than the Premier) but was "light on the line, " as predicted by the Sutton web page above. It was in fact about 1/2 of what my 7.5 was pulling in the same wind. The seems to confirm the claim that the Sutton has low drag and high lift and explains why it is a favorite for aerial photography. Note that the Sutton has no up-down bridle lines, so it cannot be adjusted to fly lower and pull harder, as you can do with the Premiers. The Sutton people claim that it will fly in lighter airs than a standard parafoil, which is a distinct plus in a light-air kite. First question: Why use a kite with low drag that flies high and is light on the line for pulling a kayak? Second question: Can you do something simple to the Sutton to get it low and increase horizontal pull (i.e. drag), without sacrificing light air performance? Something like using balloons as tails, or attaching balloons to the flight line below the kite? I have made inquiry of persons who ought to know, but no one has experience, can explain or predict. A word on kite theory (as I understand it) might help. Single line kites at steady state are not actualy "flying." They are stalled. They rise to a point at which lift is balanced by weight. The pull you feel is not lift, but drag. A stunt kite, however, generates much pull on the line as the kite moves around in its flight envelope; this pull is mostly lift. Ken Cooperstein *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
> Note that the Sutton has no up-down bridle lines, so it cannot be > adjusted to fly lower and pull harder, as you can do with the Premiers. > > The Sutton people claim that it will fly in lighter airs than a standard > parafoil, which is a distinct plus in a light-air kite. > > First question: Why use a kite with low drag that flies high and is > light on the line for pulling a kayak? Ken, That does not describe my idea of a kayak kite. > > Second question: Can you do something simple to the Sutton to get it > low and increase horizontal pull (i.e. drag), without sacrificing light > air performance? Something like using balloons as tails, or attaching > balloons to the flight line below the kite? Light air performance for sailing downwind with a kite will be elusive. Kites not specifically designed for pulling a moving boat are not necessarily best for your application. As you kayak accelerates downwind in light air the apparrent wind over the kite will quickly drop below what it will take to hold the kite aloft. Although kites are thought of as downwind rigs, they are at their worst dead downwind and difficult at best in light winds. With a multiline kite you can sometimes steer the kite increasing the apparent wind over the foil allowing sailing nearly dead downwind in relatively light conditions but with a single line broad reaching is the only way to increase the apparent wind a little. > > I have made inquiry of persons who ought to know, but no one has > experience, can explain or predict. > > A word on kite theory (as I understand it) might help. Single line > kites at steady state are not actualy "flying." They are stalled. They > rise to a point at which lift is balanced by weight. The pull you feel > is not lift, but drag. A stunt kite, however, generates much pull on > the line as the kite moves around in its flight envelope; this pull is > mostly lift. > > Ken Cooperstein I'm not sure that the emphasis of lift and drag is helpful in describing downwind kite sailing. Lift and drag may be considered abstract constructs to aid in the description and calculations of directional forces. They simplify a complex system into forces in two directions. The force is a continuous curve that might be expressed graphically as vectors. The only real practical difference between the lift and drag components is whether they are in a favorable direction. When sailing to windward lift and drag and the ratios between them are helpful in understanding the dynamics but for downwind, lift and drag are all in a favorable direction and might not be so easily seperated. For downwind kite sailing a kite that is said to have high drag might be desirable and one described to be light on the line will not be as powerful. It seems that some of the high flying single line foils will drop lower when the apparent wind drops and enter a higher drag or more stalled configuration. I have had more luck with single line kites when they had the adjustable bridles and I kept them flying lower in what might be called a high drag angle. It seems to me that the resultant vectors are essentially resolved for practical purposes into line angle. If the kite is pulling up it is lifting you up if it is pulling more horizontal it is pulling you in the more horizontal direction. The Sutton may be good for lifting cameras but may not be as good for pulling a kayak. There are some nice inexpensive two line foil kites that look like they might sail well but you would have to work out a reel system for launching them from the deck. I have been thinking about trying the "PARASTUNTER TRAINER" at about 9 square feet and only $49.95. Being about 2' by 4.5' it is a better aspect ratio than most parafoils and could possibly reach a little. Might be more difficult to launch than a single line foil but once flying should be more powerful and controllable and maybe more useful over a wider wind angle and velocity range. Good sailing Mark Mark *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
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