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 Post subject: Re: So.... whats the formula for glide?Posted: Thu Jun 07, 2012 8:42 am
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Joined: Wed Oct 16, 2002 1:00 am
Posts: 4790
Location: Denmark
plummet wrote:
That was a good read pf. my pratical experience emulated your theory..... so the theory must be correct!.

With my speed 3 there is a magical point of letting the bar out... about 1/3 when jumping. When i find that magical spot i glide A LOT longer!.

On the inflatables that point is far less obvious.

Exactly, your "feel" is absolutely correct - especially because I did not mention, that when you fly with either headwinds, or diagonal headwinds as we most often do in a "kiteglide" - you have to fly at an even lower AOA for max glide (because you need more speed to get the furthest forward, eventhough you decrease L/D), meaning you have to sheet out even further precisely as you say.

So the reason one sheets out is because max L/D happens at a lower AOA than max hangtime, but also because if you have partly headwinds, you need to decrease the AOA even further and under max L/D to get max glide

Peter

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 Post subject: Re: So.... whats the formula for glide?Posted: Thu Jun 07, 2012 11:06 am
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Joined: Sat Aug 29, 2009 11:25 pm
Posts: 1558
Location: The Naki
ok so heres a question.

If we do a jump for max glide we take off as fast as possible, send the kite to the zenith...not past and send into a lower but faster jump. We then sheet out to retain a better AOA abd L/D ration. We also turn the kite in the direction of flight to retain forward airspeed. Thats the best method for longest distance... that i've come across (lets assume normal jumping in 20 knots and not insane kite loop maniacs in 40 knots).

But the best method for max height is to send the kite past 12, turn all your foward speed into height. but at the apex of the jump we stall our foward speed and drop faster....

the question is this.

Which technique gives the longest air time? faster and lower or higher and stalling?

or given that the same potential energy do both techniques yeild the same time in the air all other factors being equal.

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 Post subject: Re: So.... whats the formula for glide?Posted: Fri Jun 08, 2012 7:23 pm
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Joined: Tue Jul 19, 2011 5:26 pm
Posts: 110
Location: South Africa
Best hang time- good question. I've also wondered about whether it would be from height, or glide, but I think both are similar.

The most important factors for hang time I'd think are gaining minimum downwind speed, while at the same time getting enough lift all the time. Going downwind decreases relative wind speed. Not getting enough lift obviously decreases hang time. But you all know this (sorry if I missed in if its in the posts already)

What I think works best is to go for a max height, but move the kite around. Since the kite alone has less drag than your body+kite, the glide technique has more drag than the height technique with sweeping the kite around. But then again, the glide technique allows you to sweep the same amount of area (thus get more energy out of the wind) while still keeping all this force vectors straight upwards instead of wasting energy by pulling you slightly left/right as is the case when throwing the kite around. My first assumption might be wrong.

What I also find is that it's best to sheet the kite in gradually as you gain height/ slow down on the upwards motion of the jump. This I think maximizes L/D, since L/D is better sheeted out when you are fast, and maximum sheeted in when you are slow.

To increase the length of time you are in the are before the downwind speed gets too much it is probably best to get maximum upwind momentum by edging upwind with perfect timing before the jump.

Quite technical if you try to think about everything. I didn't expect so many factors that need to be considered.

I think the glide vs height techniques are so similar in terms of hang time, that other factors probably override any noticeable differences. Most likely one's timing is better suited for one, or the other, and then your hang time is best when you stick to your better method.

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 Post subject: Re: So.... whats the formula for glide?Posted: Sun Jun 10, 2012 1:16 am
 Very Frequent Poster

Joined: Sun Jan 04, 2004 6:56 am
Posts: 3733
Location: Kailua, Hawaii, currently riding EH and OR kites (2013 Razor rocks!)
Well, first you got to quit flapping.... glide, by definition, means that you quit flapping and let the air carry you smoothly...

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