OTHER AVAILABLE TRACTION KITES Flexifoils The "original" and most popular traction Kite. At present, users report that Flexifoil powered buggy/kitesailers do not have good upwind performance. I have tried buggying/kitesailing using Flexifoils, there is no theoretical reason why they shouldn't be excellent for the job, and they are, especially in stronger winds and when you have plenty of space to build up useful apparent wind. Even though the Flexifoil airfoil profile is not a "conventional" high L.D.R. form its L.D.R. is at least up with what is currently available from its rivals in the traction kite stakes. In terms of M.M.R. it seems to me that by using more flexible front spars there is available a simple mechanism to reduce their maximum pull without sacrificing pull at the edge. A third consideration, that larger Flexifoils require too much arm movement to effect adequate control is easily resolved by using a pulley system or by using a stack of small Flexifoils. Rigid Frame Stunt Kites Before developing the "Peel" range of soft stunters I used rigid frame delta style stunt kites extensively for kite traction. They have considerable natural advantages: control is good, kites can be made in almost any desirable size (I built a series of 5.5m wing span stunters) or smaller stunters can be stacked to get sufficient pull. They have a built in mechanism to improve M.M.R.. By utilising spar flex and skin stretch, delta style stunters automatically "twist off" at their wingtips as pull increases giving very good M.M.R. This desirable characteristic can be enhanced by building stunters with extra windtip area, held out by battens, which only generates lift when the kite's apparent wind is low. Although the recent trend has been for delta form stunters to tend towards long tapered wingtips the reason for this has particularly to do with the rules and requirements for "precision" stunt kite competitions. Kites for traction don't need to follow this trend. One kite style that should have considerable potential as a traction kite, for the reasons outlined above, is the Volkensturmer 101 from Germany. Another design which should also have very good inherent M.M.R. is the speedwing from Vlieger Op in Holland. Lacking a spine, it contrives "twist off" in the middle of the skin again by spar flex and skin stretch. Four Line Kites Four line kites have almost total control of M.M.R. and would, theoretically, seem to have all the advantages for kite traction use. Indeed "Revolution" and "Quadraflex" kites are commonly used for buggying. That four line kites have not yet demonstrated competitiveness in buggy racing and do not yet appear to have made any significant impact on kitesailing could be because of a number of reasons. Maybe I have not yet, met adequate four line buggyers! Maybe current four line kites are not big enough or, no matter that a kite has good M.M.R. it still must have good L.D.R. to be suitable for kite traction or, another possible reason is that the ability to "sweep lots of sky" a supreme characteristic of two line kites is an overwhelming racing advantage even though this technique can only be used on non-upwind legs of racing courses. But, why cannot four line kites also be used to "sweep the sky"? It's just a matter of having greater flier skills. During 1990 I built and raced with four line versions of the Peel (set up for angle of attack control rather than full reversing ability). At that time these kites were definitely not as fast around the buggy course as standard Peels. Why was this? I note, analogously, that in International "A" class catamaran racing, sails that are constructed with good built in gust responsiveness are consistent winners against probably superior sails that require continual operator adjustment for optimum performance. A year ago I said I would still not be totally surprised if four line kites eventually prove superior for kite traction. Now I will be surprised if they don't eventually become the traction kites to beat. Thinking this through, to balance against the advantages of self launching capability (even off water to some extent) and superior control, the only necessary disadvantage of 4 lines is the extra drag of two more lines. However, I'm not sure that any of the current crop of 4 line kites have the necessary characteristics. Perhaps the new Legaignoux kites will have, but it seems to me that an essential characteristic is high lift/drag ratio (L.D.R.) for which a higher aspect ratio is require (roughly span/chord) than either of these kites or the Quadrafoil have. The Peel does have adequate aspect ratio and can be easily rigged for 4 line flying - See Peel Bridling Data. For the purposes of kite traction 4 line kites need to be divided into two types. The first type, like the Quadrafoil and Peels rigged as per the method described later use the 3rd and 4th lines to operate trailing edge brakes which provide for very rapid turns, stalling (great to prevent luffing including A.W. luffing) and even upside down relaunching. The second type, like the revolution, give full control of angle of attack and can therefore be used also for de-powering the kite. This is a major advantage.