On 2002-09-06 13:15, Royce wrote:
Again, fair enough comments. I have done my fair share of parragliding and the reason that there are no lei's is because you don't have to relaunch your wing. Once you hit the water Bummer Your flight is over. The reason that there won't be any major developments in Foil kites...more lift = more drag...less lift = more speed but less flight time. That is the formular that everyone is working with. On a foil you either make the shape of the wing more efficient...maybee small changes or you reduce the drag. Only way to do that is by making a thinner aerofoil. LEI's will have more major development. Look for a kite that adjusts the angle of attack radically in the air. Pull the bar instead of increasing it 3 or 4 degrees it'll be 15..right to the edge of a stall. Change is a commin. As for RnD on foil kites...there are no more calculations to be done. Go get a parraglider formula program and voila theres you kite.
May i point at the fact that both the "LEI" and "FOIL" are airfoils ? both have a certain profile[airfoil] that gives a great deal of the aerodynamic properties to the kite, and the aerodynamic laws don't change. This means that it's also treu for LEI's that more lift=more drag
The difference is the construction, a LEI is far stiffer than a ram airfoil design, so its likely that it can withstand a bigger AoA variation than a ram airfoil. In that point it's easyer to design and build a LEI with enough depower...
BUT a ram airfoil design is theoretical more efficient than a LEI, because it doesn't create turbulent airflow after the tube.
It takes a lot more R&D to make an ram airfoil design suitable for kitesurfing. (mainly depower and stability)
Just the last 2 years or so the foils become suitable for k-surf, and it takes a LOT of R&D to make it so.
It's ridiculous to think that foildesign has come to a stilstand and that everything that can be done with foils is done, the same is true for LEI's.
By the way, programs that calculate LEI's do also exist so designing a good LEI is also just a simple calculation on the computer ? Don't think so...
So please, choose the kite that fits your best, just don't ignore new devolepment at both the LEI and the Ram airfoil
Imho, the best properties of ram airfoils and LEI's combined will be the better kites in the future...
Have fun, Henry
(Who don't want to flame)