this is an amusing discussion. however the original poster asked about big boosting kites!,,,,, its a 4 page thread hijack.

I think I covered it adequately as an undergrad. I do not dispute the theory that has been applied. I am just pointing out that it fails to tell tell the whole story. More energy is added to the system AFTER launch...

I started paragliding in 1993. Localised air currents (apparent wind) and their impact on the kite are exactly what I am talking about. Do you seriously mean to tell me that you have never experienced any sort of pull on your lines after launching? Am I defying the laws of physics when I do a standing start by jumping off the beach?

I appreciate the science which I can - partially - follow ... but ...
... when I jump and I'm hit by a wind gust, I suddenly - and while being airborne and expecting to drop - feel so much upward pull that I can't resist shouting with joy for the extra height. I hope that conservation of energy does not exclude this phenomenon or else I and all my kite buddies are in need of an urgent MRI scan to exclude hallucinogenic brain illness. Could it be localized vertical current or the horizontal air flow creates lift because of the foil shape of the kite? (I really don't care a lot but I would like to know for next time )

I think that's the point edt & js are making, jimovo - in a simple, perfect system conservation of energy determines the maximum theoretical height of a jump ... all other factors equal. Gusts on the way up are outside the described model ...

I should have intuitively understood this - since I started kiting, I've been basing my kite-selection on what the locals are using plus 5m2 just to ride upwind as well as they can.

Thanks! I learned something

I understand that wind gusts are not welcome in a simple perfect model. I suspected that all the argument here is between theory and real life and so it is. I also learned something on this thread. Now, can we give it back to the OP - as Plummet pointed out - and propose a high boosting kite? North Rebel for example? Any suitable size ( + 5 sq meters for Kami)

This is obviously a factor but not necessarily my point. Even if the wind does not change in direction or strength through out the entire jump, the kite can contribute lift after the rider has left the water. It can not do it indefinitely due to the 'pendulum' effect however it is still a significant contribution to max height.
I can tell you straight off that my kite 'pulls' me up. If you can't tell from your own experience then take a look at any video you please showing a kiter jumping. If the kite is above the kiter and the lines are tight then it is contributing lift....

Gusts are welcome (although I wouldn't characterize fundamental aerodynamics and the law of energy conservation a 'model').


Regarding both of the quotes above:
In case you didn't read this (posted early in this thread), here again is a detailed article about relevant dynamics, followed by detailed discussion about some of the factors that inevitably arise intuitively, albeit erroneously:
http://kiteboardbc.com/phpBB3/viewtopic.php?f=1&t=175


Quite right. Sorry.

Best regards,
James

from the conversation held should i conclude a big boosting kite would need to:
1) be fast (for max horizontal speed)
2) turn quick (for the ability to instantaneously convert horizontal speed into height with mininal loss)
?

what are the kite design caractheristics that would lead to 1) + 2) ?

You think I'm joking? Last Saturday, everyone was riding 9 or 10m kites (7m for the real lightweights - approx 50kg ) and I launched my S3 15 and had a blast! I might have been ok on the Xbow 16 but probably would have gone with the 13 for safeties sake - it was pretty gusty ... and the water was mad choppy so it was tough holding an edge for long enough to load up for a big boost.

I'm surprised nobody has put this spoon in the pot to stir ... kite loops

Hoho, I am still reluctant to try my Speed3 15 in >13 knots, I did it unvoluntarily in the past (the wind picked up mid-session) but it was a time that I did not know how to get anything else out of this kite other than going back and forth... Now everytime it is windy I change to my Vegas 9 to try things which need a kite that moves to be performed. But I have to try it in stronger winds, I expect it to be a heaven of hangtime, considering its hangtime in light wind... !

And, yes, we don't need kiteloops in this discussion, it can only make it more complicated. Let's not discuss loops, let's just do them!