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Pulleys on kites

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Bille
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Re: Pulleys on kites

Postby Bille » Thu Jan 04, 2018 2:22 am

OzBungy wrote:
Thu Jan 04, 2018 12:54 am
Prototype paragliders are made with multiple attachment points and lines with knots and loops.
..

Paraglider line sets are vastly more complex than a kite bridle.
...
The designers of Kites for kiteboarding ; their more than 10- 15 years behind the shit
they got for a PG. Guys like Rob Whittall from Ozone , who was world champ for both
hang gliding and paragliding... ; you don't think he's got brains and talent, to stay ahead
of the curve ? Then think of how Ya tune your ram-airs with the different bridals from
A to D's & breaks for AOA changing in the airfoil CL-Max on a water-kite ; well the PG's
thought of a way, that's WAY more complex to tune a kite , with infinite selection for change
over each segment of cord , with this thing called , "La Cage" pictured below.

HELLO !!!!!!

But seriously a PG doesn't need any tricks like La-cage , to technologically stay out in front
of a fricken water-kite ;
--- They already got that covered !! -------Sorry ,not Really :lol:

Bille
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OzBungy
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Re: Pulleys on kites

Postby OzBungy » Thu Jan 04, 2018 6:05 am

I know that the technical design of many kitesurfing kites is done by paraglider guys.

As far as I know the tuning process would be similar. Test pilot rides. Identifies an issue. Designer and rider work out a modification. Implement it. Test it. Repeat.

A kite has a semi-rigid structure, a tiny bridle, and a small number of attachment points. A paraglider is soft and flexible, much more critical in it's safety and performance, 40-80 attachment points. They do it easy for a smaller market.

Why is there this "good designers don't use pulleys, but it's really hard" vs "lazy designers use pulleys because it's easy"? It doesn't look that hard to me if you're a professional designer with lots of practice and the required tools.

That still doesn't let the armchair experts off the hook. Us guys still know shit.

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sflinux
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Re: Pulleys on kites

Postby sflinux » Thu Jan 04, 2018 9:24 pm

IMO pulleys on kites are a comprimise. Why? A kite without a pulley on the leading edge bridle may not be able to do a traditional water relaunch. A kite without a pulley on the steering lines, may not be able to do a reverse relaunch. I prefer kites without pulleys, especially on the leading edge, as they have a more direct feel to them. Bar pressure is more related to bridle attachment location.
For e.x.: the first generation Cloud kites had pulleys because Greg thought they were necessary. He later learned that they are not and the kites perform better without them.

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Re: Pulleys on kites

Postby mr_daruman » Fri Jan 05, 2018 2:54 am

I have no experience in paragliding but these seem to have a long history in briddle design, are pulleys necessary/used in the bridles?
Ozone can achieve with no pulleys super light bar pressure (like it or not) great depower, mixed with good bar response so whats the deal in adding more mechanical parts. I think its just good kite+briddle design.
The same is true that you can make a great designed pulley kite...But I feel this can be designed and tested "faster" and for cheaper. And...sometimes shortcuts can be taken. Good or bad.

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Re: Pulleys on kites

Postby Ianw » Fri Jan 05, 2018 7:00 pm

TheKiteDesigner wrote:
Tue Jan 02, 2018 7:08 am
With a pullyless kite every bridal line has to be accurate to half a centimetre with a kite with pulleys there is a lot more forgiveness if you get a measurement not quite right in my experience it's much harder to make a good kite without pulleys. A kite without pulleys can outperform any other kite with pulleys it's just much much harder to design.
So for pullyless kites I guess it's critical to check for bridle line stretch:- https://ozonekites.com/images/uploads/p ... -Check.pdf

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Re: Pulleys on kites

Postby OzBungy » Mon Jan 08, 2018 1:42 am

mr_daruman wrote:
Fri Jan 05, 2018 2:54 am
I have no experience in paragliding but these seem to have a long history in briddle design, are pulleys necessary/used in the bridles?
...
Paragliders have mostly no pulleys in the bridle at the wing end. At the bottom end (near the equivalent of the bar) they all have pulleys and some are getting more pulleys.

They have one or two pulleys to give a mechanical advantage when you push the bar out. There is a lot more pressure on the bar and you push it with your feet. It can be physically quite tiring, especially on long glides, even more so in turbulent air. :o

They almost all have a pulley so that when the bar is pushed out, the second row of lines is pushed half way to keep the camber of the wing constant. It is a very bad thing to introduce more camber by bending down the front of the wing when you're trying to go faster (the wing collapses violently). This is somewhat equivalent to the role of the pulleys in a kite bridle, to keep the designed profile constant.

High performance wings might have pulleys so that the tips are not pulled down as much as the rest of the leading edge. This makes the tips more solid at high speed.

Newer wings are adding a pair of pulleys so you can pull down the trailing edge to counter the effect of the speed bar, but avoid a wrinkle in the back half of the wing.

A lot of paragliders have a trailing edge gathering system to increase the steering efficiency. That is usually a ring, or a Y-shaped line that pulls the trailing edge in slightly. Very new wings have left this out in favour of having a longer brake fan with less connections that naturally pulls the trailing edge in.


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