taiguy wrote:UKSurf wrote:Why does a 10m kite have 4x the power of a 5m in your first chart? I would think it would have 2x approx. also the power seems to be increasing with the power of 4 not power of 2 for wind speed. We need Bill Hanson to confirm these figures before they are used to purchase a quiver
I haven't seen any information that would corroborate edt's claim.
Power increases with respect with the square of the area and cube of the windspeed. But please have Bill come and give us all a short course
taiguy think about it for a second, it is ridiculous to go with cubed.
If you go with v^3, then if you fly a 12 meter kite in 20 knots, in 30 knots you need a 3.5 meter kite.
If you go with v^2, then if you fly a 12 meter kite in 20 knots, in 30 knots you need a 5 meter kite.
You can't just look at wikipedia without noting that when they give these figures of v^3 is it not for a kite it is for a turbine. The turbine spins faster the higher the wind. This means it extracts one additional factor of v. If instead of a turbine you are measuring the amount of force pushed back against a car it's 1/2 p v^2 Cd A go look it up, that's because unlike a wind turbine the car doesn't spin around in circles it just sits there in the air.
Anyway, just crank out a few numbers and example kite sizes it's pretty easy to see right away v^3 makes absolutely no sense.
Also kite size and rider weight scales linearly. Only wind speed scales as square for figuring kite size.
So a 20 meter kite pulls twice as hard as a 10 meter kite, and a 200 pound rider needs twice the kite size as a 100 pound rider.