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 Post subject: Why is 'no pulleys' now good?
PostPosted: Wed Aug 14, 2013 3:21 pm 
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A couple of large manufacturers have removed most or all pulleys from certain models of 2014 kites, claiming things like "more direct feel", "improved flying and acceleration" and other good things.

Of course, none of the manufacturers say anything negative about removing the pulleys. I was not in tune back in the mid 2000's when pulleys were added to bridles, so what was the point of adding the pulleys? And why has it taken until 2014 models to remove them?

Pulleys have been a point of failure, and obviously cost. Some say they add a "mushy feeling" to kites, so why did they even add them in the first place? Surely manufacturers weren't anxious to add cost to bridles for no reason.

If I buy a new model that now comes with no pulleys, what can I expect to lose in terms of performance? The manufacturers tell me what I gain with no pulleys, but not what I will lose.


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 Post subject: Re: Why is 'no pulleys' now good?
PostPosted: Wed Aug 14, 2013 3:36 pm 
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Kite designer back in the day used pulleys to increase speed and depower, I have actually taken pulleys off and modified the bridle with a pigtail to slow down kite I thought was to fast. With newer design cuts they are really a weak link.


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 Post subject: Re: Why is 'no pulleys' now good?
PostPosted: Wed Aug 14, 2013 3:43 pm 
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Last edited by Peter_Frank on Thu Aug 15, 2013 11:05 am, edited 2 times in total.

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 Post subject: Re: Why is 'no pulleys' now good?
PostPosted: Wed Aug 14, 2013 4:04 pm 
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If you are a kite designer and your kite don't fly right, a easy fix is just add a pulley, the kite will then self balance on the pulley, if for some reason there isn't enough depower in your kite you can lengthen the bridle and add a pulley. If you do not use pulleys at all and use direct attachments, then what happens as the kite rotates and decreases aspect (depowers / pulls more upwind) is that the tension of the bridle moves from the outer edge of the bridle towards the inward attachment points. If you aren't careful with your design and use a fixed bridle the kite will simply taco. One fix for preventing the taco is to increase the leading edge size, but this decreases performance. Or you can add a pulley. Another problem is how to flag out your kite. If you use a fixed bridle you need to design a sort of system where the kite line can pass through the bar, that nothing catches and it doesn't wear too fast. If you use a pulley you don't have to do any of this, you can just clip onto the depower rope, or just let the throw go for a meter or two and the pulleys will tilt the kite back.

So pulleys are a way to fix any number of design problems -- BUT .. . .

one problem. pulleys give the kite a slow soggy feel. It is not the direct responsive feel that a C kite has.

So what to do? What you want to do is decrease the size of the bridle. If you make your bridle small enough you can either not use pulleys at all, or use a slider, since the kite won't be sliding as much in a short bridle you don't need the pulley as much. The price you pay here is decreased depower. But it's worth it as you have a more responsive kite. A kite that has massive depower throw (except for 5 line kites) will always have a soggy feel because of of the length of the bridle needed and the pulleys. 5 line kites like the rebel do this all differently, the 5th line is under tension so you have the crisp feel of a C kite and the massive depower of a pulley kite. The drawback here is you have a 5 line kite, one more extra line to set up and the kite can bow tie on the 5th line.

One last thing that sucks about the long bridled pulley kites is getting a bridle tip wrap that can death loop your kite.

It's all about tradeoffs. I think my favorite kite is the ozone catalyst no pulleys very direct feel agile in the air, I also like the wainman boss, very short bridle so even tho it has a pulley it has a very direct responsive feel.

It's not actually the pulley by itself that makes a kite feel soggy in the air it's the combination of a long bridle and a pulley. Just putting a slider instead of a pulley in your kite I don't think makes it any better, you want to shorten the bridle and go with sliders instead of pulleys. I think the soggy feeling is caused by the pulley racing along that long bridle line until it finally gets into place, and that will still be there if it's a slider that has to move along the bridle or a pulley. With a shorter bridle the pulley doesn't have as long to go, so it doesn't wear the bridle so much and a slider seems more appropriate.


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 Post subject: Re: Why is 'no pulleys' now good?
PostPosted: Wed Aug 14, 2013 4:31 pm 
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southflorida wrote:
A couple of large manufacturers have removed most or all pulleys from certain models of 2014 kites, claiming things like "more direct feel", "improved flying and acceleration" and other good things.

Of course, none of the manufacturers say anything negative about removing the pulleys. I was not in tune back in the mid 2000's when pulleys were added to bridles, so what was the point of adding the pulleys? And why has it taken until 2014 models to remove them?
...

Pulleys were added when LEIs went from typically 4 direct connected lines to SLEs and bow kites which all had some sort of a bridle.

Now that the kites had bridles, they had to solve the problem where the actual geometry of the bridle changes based on the angle of the kite to the rider. (changes based on bar input, position of kite and wind). Putting a pulley where a line attaches to the bridle took care of this. It gave the designers a "slop" factor so that all the bridle lines could remain taught and the load was evenly spread.

There's likely a more confusing and more accurate description than that, but there is a layman's explanation. :)

Since then, some designers have found ways to make mini bridles that do not require pulleys. There are pros and cons of pulleys. They are not all bad, but they do jam up with sand and then the wear on the bridle line is greatly increased.


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 Post subject: Re: Why is 'no pulleys' now good?
PostPosted: Wed Aug 14, 2013 5:04 pm 
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as a mater of fact I asked Blade for a way to increase the feel of a kite I own (with pulleys) even at the expense of de-power, etc. and got the reply that I could try to take out the pulleys and see out it goes..

thing is I like to ride way more than I like to play Momi...still in to-do list

does anybody has any experience in such a mod?


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 Post subject: Re: Why is 'no pulleys' now good?
PostPosted: Wed Aug 14, 2013 5:45 pm 
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southflorida wrote:
...If I buy a new model that now comes with no pulleys, what can I expect to lose in terms of performance? The manufacturers tell me what I gain with no pulleys, but not what I will lose.

only thing which 4 line kite with pulleys do better is flagging on two front lines. you can not fully flag fixed bridled kite without making bridles very long.

all the rest functions are better with fixed short bridles. short i mean a bridles that can not let the wing tip through them during kite being fallen in water.

but sadly manufacturers often make big changes in designs only for the sake of them, and not for real necessity to change anything. like with the super thin LE bladder, too low wing profile or even numbers of struts on kites. some of the brands got really obsessed with it.
but most demonstrative example was naish sigma zig-zag leading edge, now ingloriously vanished...


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 Post subject: Re: Why is 'no pulleys' now good?
PostPosted: Wed Aug 14, 2013 10:04 pm 
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I like pulleys in kite for medium-strong wind. I think increase stability and windrange.


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 Post subject: Re: Why is 'no pulleys' now good?
PostPosted: Thu Aug 15, 2013 12:47 am 
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It's mechanics. Pullies give more options in power/depower / steering/ drifting.

But they can break, wear, jam and contribute to deathloop likelihood.

Fast turning kites can be dangerous in deathloop modes as they keep on spinning.. and suck for wakestyle (too fast), but make for easy kiteloops and less chance tendon problems in u have those kind of problems..


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 Post subject: Re: Why is 'no pulleys' now good?
PostPosted: Thu Aug 15, 2013 2:11 am 
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edt gave a very good explanation with good examples like the five line set up. Pretty hard to top but I get a feeling nobody understood. I will work with another example. The 2006/2009 Ozones used five line set up with dynamic self adjusting fifth line. In five line setup the two fronts and the fifth are the bridle and that was the perfect bridle you could adjust it (power/depower) by changing relationship between front lines and the fifth and then set it solid. The equivalent to that would be a pulley bridle where you could stop the pulleys from moving after adjusting depower. So Ozone to get away from the dynamic fifth which was complicated came to the conclusion that a short set bridle would be the next best thing. The other companies would still be in the dark today if Ozone wasn't winning all races and speed contests.


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