I believe the discussion was whether weight had anything to do with jump height. Same kite size, same conditions, lighter will jump higher. Right?

Change kite size to accommodate different weight riders and it seems that is an acknowledgement that weight is an issue.

I'm impressed with the scientific justifications forwarded in this thread, but weight makes a difference, IMHO...

IF the height to which a kiter can jump only came only from the kinetic energy due to the riders momentum then the riders weight would have little bearing on the height to which they could jump. In this case the maximum achievable horizontal speed would be converted to the maximum height vertically. A larger rider will have more kinetic energy for a given speed but it takes more energy to raise them to a given height, conversely, a lighter rider has less energy for a given speed but it takes less energy to loft them up.

However... the reason that this is not matching up with peoples experience is that this is only part of the story. The contribution of the kite to lifting the rider AFTER the launch is entirely missed in this model. It is this part of the equation that IS dependant on the mass of the rider. A kite is perfectly capable of continuing to provide lift while the rider is airborne and the kite is directed correctly. The effect of the lifting force on height very much depends on the mass of the rider....

It's not the kite....it's the kiter

I think fatty can also hold more power and that might cancel out the inertia. So where skinny goes on a 9 fatty takes the 12. Now lets also discriminate between fatty fat and fatty heavy on the muscle. The muscle fatty will hold more power given equal level technique.

OK, I think some of us were missing each other in the discussion. If the big guy has a bigger kite to compensate for weight, then yes, he may well jump higher. Look at speed records in kiting and windsurfing. They're not being set by small people.

And yes, the kiteR has the biggest effect of all!

Peter

Ah, now I see - we're talking ideal systems where such thing as appropriate kite sizes cancels out between Fatty and Skinny.
"You're ignoring ..." No, I'm just ignorant of been many years since my high school physics classes ...
So maximum theoretical jump height is the same based on conservation of energy ...

TT - lets not forget fatty Fatty with bigger balls than Skinny

i'll explain again. This particular model does not depend on the mass of the kiter.

there are two vectors.

1) kiter in relation to water

2) kiter in relation to wind

1) For the kiter in relation to the water, he pops. His vector is directed upward. It does not depend on his mass any more than a BMX biker doing a jump depends on his mass.

2) At the same time the kiter redirects the kite to boost.

The model in this case says that the kite has the same mechanical properties as a tack stuck in the wall with a lead weight swung from it. If the tack is big enough (if the kite is big enough), then the lead weight's direction will change from one direction to the other. It does not matter how big your lead weight is, unless you decide to put in a tiny little tack (under power the kite).

Think of it as sticking your kite in the air. You have already popped out of the water, and all of your horizontal motion relative to the water has been converted upwards. But the kite (and yourself) still have a lot of speed relative to the speed of the air, and you want to convert this to vertical height too. You use your kite in the air as a pivot to change your horizontal motion into potential energy. Then both you and the kite rise up in the air.


Now I'm not saying this model is perfect. But it does say, if you have enough kite, it doesn't matter how much more kite you won't boost higher.

So for instance suppose you go out and it's 25 knots and you are lit on your 10 meter.

Then you switch to your 20 meter, and you get worked up and down. You go to jump anyway.

Do you go twice as high on your 20 meter as you did your 10 meter?

Or did the 20 meter just let you drift down a lot slower?

Anyway, I'm not defending this model, just trying to explain it properly so you understand why your objections are not proper objections, they stem from a misunderstanding of this particular model. Even though vectors 1 and 2 come from different places you can just add them together for 1/2mv^2 = gmh, where v is velocity relative to wind, that's how vectors work. Notice the 'm's the mass cancels out here.

You needn't bother - If you read my previous posts then you will see that I have agreed that in a model such as you describe, the riders mass is irrelevant. Your equations are indeed correct. The reason that you are encountering resistance from kiters trying to relate what you are saying to their real world experience is because the model itself is not an adequate description of what you are applying it to. Why keep attempting to explain it when it obviously misses a large part of what really goes on? As I have said previously, your model is the equivalent of detaching from the kite the instant you are moving vertically - it completely ignores any contribution of the kite in gaining height due to lift generated while you are in the air. Is there anyone here at all that believes that their kite can not continue to pull them in an upwards direction while they are in the air?

I think you're right. I described the kite's contribution a couple of times, should have quit after the first time.

Yes.

Learn about conservation of energy.

Also, ask hang gliders, paragliders and glider pilots why their craft don't glide upwards (barring localized vertical air currents).