Re: [ksurfschool] Lofting danger!
- Hi George
Thanks for posting that calculation, it should be part of every instructor
course, should also be part of every kiteboarding lesson, and should be
tattooed on every experienced riders forehead.
Especially people from a non power kiting background like wakeboarding,
windsurfing, etc, they have no idea about this LAW of physics.
----- Original Message -----
From: "George Sarris" <jakefarley2000@...>
Sent: Wednesday, June 23, 2004 5:03 AM
Subject: Re: [ksurfschool] Lofting danger!
> In my opinion 10kts with gusts to 30kts is too
> extreme. We must remember that the lift on an airfoil
> increases exponentially to the wind speed.
> The formula for Lift is:
> Lift = ½ ( 1.2 * Area * Coeff of lift * Wind
> Speed(squared) ).
> Assuming a coeff of lift of 1.0, using 9m projected
> for a 12m flat area kite, the lift would increase from
> 143 newtons (or 15kg force) at 10kts wind speed to
> 1,286 newtons(or 131kg force) at 30kts wind speed.
> This is almost a factor of 10 times the lift or force
> on the kite.
> --- Hung Vu <hungvu2000@...> wrote:
> > I got my first serious lofting experience today and
> > fortunately in the
> > water so I was very calm and observed all the facts
> > to report it here.
> > 1- The wind was very gusty probably from 10 to 30
> > knots.
> > 2- I was struggling to trying to come back to the
> > beach (a very narrow
> > section of the beach around 200' or so)
> > 3- The gust came unexpectly and lift me 20' in the
> > air and probably 50'
> > down wind
> > My observation:
> > Forget about trying to unhook or "pulling on
> > something", lofting happens
> > so fast that I AM NOW VERY SURE that only "dropping
> > the bar" MAY
> > (probably 40% to 50% "MAY") work.
> > P.S., I was using a GlobeRider 12m and a small
> > custom board.
> > P.P.S., This is not tea-bagging as tea-bagging only
> > on lift 5' or so.
> > P.P.P.S., It was fun in the water but I bet it would
> > not be so fun on
> > land...
> > Hung.
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