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Explain bar pressure please

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Giorgio
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Explain bar pressure please

Postby Giorgio » Mon Nov 06, 2017 6:59 am

:?: :?: :?: :?:

Hi all,

can anyone explain bar pressure?

I know that more bar pressure is often good for unhooking. I moved from a Envy to a GTS 4 and find that my unhooking has worsened, i often get less air than i did with the Envy.
I think it has to do with position of the kite and possibly with bar pressure - i think i can't keep the edge very well until when it is needed.

The GTS 4 comes with setting to increase/decrease bar pressure. So far i use the mid-setting, should i try to change for another setting? do they make a difference?

Mostly i would like to understand well what bar pressure means, is it something linked to how much powered you are? when you ride unhook normally you would depower to a point where you can conformably ride with the bar fully sheet-in (right?)... so how does bar pressure help unhook riding?

Lots of questions...

thanks :D

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Mitaka
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Re: Explain bar pressure please

Postby Mitaka » Mon Nov 06, 2017 9:33 am

This question comes again and again. :D

Bar pressure is:
1 The force needed to keep the kite and certain angle of attack when kiting.
2.The force needed to turn the kite.

Light bar pressure means less force needed. Changing the bar pressure with different wingtip attachment points has the following simple explanation:
Imagine the kite is a simple leverage system where the front line attachment point is the fulcrum and the rear line attachment point is the place where force is applied (for simplicity no bridles are used and the from lines are also connected directly to the leading edge).
lever figure 1.gif
lever figure 1.gif (4.2 KiB) Viewed 618 times
When the rear line is attached closer to the wingtip (setting A on Cabrinha kites), which means further away from the front line attachment (fulcrum), you need less force to keep the kite at certain angle of attack. You also need less force to turn the kite (change angle) BUT you need more travel! Simple physics! :D
On the other setting B (away from the wingtip, closer to the fulcrum) you need more force BUT when turning the kite you also need less bar travel to achieve the same change of angle!
IMG_6251.jpg
Same bar travel has more effect on setting B then setting A.
Since the travel is fixed bar fully sheeted out will allow a little bit more "De-Power" on setting B.

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Re: Explain bar pressure please

Postby Toby » Mon Nov 06, 2017 10:05 am

With higher bar pressure you can feel the kite more.

Imagine cars: power steering is convenient, but direct steering makes you feel your car way more and you can do better turns.

Also important for hooked tricks to exactly know where your kite is and heading to.

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Re: Explain bar pressure please

Postby jeromeL » Mon Nov 06, 2017 1:20 pm

My last unhooked session I tried higher bar pressure but was too high, I was too tired after 4 days of kiting, put it back on low and was a lot easier.
As far as getting less air unhooking I don't know what you mean and never tried GTS I personally don't get that much air, maybe you need more speed and power... often C shape run a bit smaller.

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Re: Explain bar pressure please

Postby edt » Mon Nov 06, 2017 2:27 pm

When you ride hooked in you are free to move the depower rope around however you like. When you ride unhooked, you don't have much choice. You have to give the kite about 1 inch or so of depower (so it doesn't backstall) and that's it. If you give it 2 or 3 inches it hurts the pop of the kite too much. Unhooked, if your kite is too big and you find yourself reaching for the depower trim to depower the kite you need to switch to a smaller kite. The pop depends on the kite being powered properly, and if the kite isn't properly powered there's no way you'll get enough pop to do any tricks. As for how much bar pressure there is, that's kite dependent. Kites like the RPM have settings you can increase the bar pressure on, but it won't necessarily make the kite better for unhooking. It's not the bar pressure that makes a kite great for unhooked tricks, it's the pop and slack. Also, when people talk about "bar pressure" they only mean how much pressure the kite has when you are riding around hooked in. Once you unhook, 100% of the kite's power is transmitted through your arms, so there's no such thing as bar pressure there, you are just holding the entire pull of the kite so it doesn't count as "bar pressure". As for greater bar pressure allowing you to "know where the kite is" I think that doesn't matter. You get used to your kite and even with low bar pressure if you know your kite, you will feel where it is without having to look at it. The real advantage to greater bar pressure is that the kites which have the highest bar pressure (C kites) also happen to be the best unhooked. But if you find a great C shaped kite that has a bridle with lower bar pressure and it has great pop and slack, there's no real disadvantage to having a lower bar pressure it just means you can ride longer without getting tired out. If you ride C kites all the time your arms get strong enough that you don't worry about the higher bar pressure after a while.
Last edited by edt on Mon Nov 06, 2017 2:32 pm, edited 1 time in total.

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Re: Explain bar pressure please

Postby pj sofine » Mon Nov 06, 2017 2:29 pm

I always thought bar pressure was the amount of force it took to sheet in and hold bar in and keep powered up.Never thought bar pressure applied to an unhooked bar or hooked in turning of the kite.hmmm :duh:

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Re: Explain bar pressure please

Postby edt » Mon Nov 06, 2017 2:32 pm

pj sofine wrote:
Mon Nov 06, 2017 2:29 pm
I always thought bar pressure was the amount of force it took to sheet in and hold bar in and keep powered up.Never thought bar pressure applied to an unhooked bar or hooked in turning of the kite.hmmm :duh:
that's exactly right pj. It's how much pressure it takes to hold the bar sheeted in. It just so happens that the physics works out so that when you change the attachment points so that the kite turns slower, that also gives you more bar pressure.

Oh and Giorgio for the settings for your GTS try all the settings!! You never know the kite might give you better pop on the "less bar pressure" setting.

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Re: Explain bar pressure please

Postby pj sofine » Mon Nov 06, 2017 2:46 pm

edt wrote:
Mon Nov 06, 2017 2:32 pm
pj sofine wrote:
Mon Nov 06, 2017 2:29 pm
I always thought bar pressure was the amount of force it took to sheet in and hold bar in and keep powered up.Never thought bar pressure applied to an unhooked bar or hooked in turning of the kite.hmmm :duh:
that's exactly right pj. It's how much pressure it takes to hold the bar sheeted in. It just so happens that the physics works out so that when you change the attachment points so that the kite turns slower, that also gives you more bar pressure.
Any of the old crowd can remember what real bar pressure was! Ran a windsurfing harness line to hook into. Stuck in a non releasing chicken loop and harness line Now that was pressure! And no easy way out as you got potentially dragged to your death.Those were the "old days",not the "good old days" :thumb:

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Re: Explain bar pressure please

Postby kitexpert » Mon Nov 06, 2017 4:09 pm

edt wrote:
Mon Nov 06, 2017 2:32 pm
It just so happens that the physics works out so that when you change the attachment points so that the kite turns slower, that also gives you more bar pressure.
Higher bar pressure due to shorter leverage (backline attachment closer to frontlines) should not give slower turns. Same amount of sheeting (or turning input) makes then bigger reaction in kite, so turning should be faster :wink:

If you had an extension, like some rigid stick at the wingtips and you could move backlines far back your steering input would be very weak and turning very slow. This setting would give of course less bar pressure, not more.

Which physics is correct :?: :)

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Re: Explain bar pressure please

Postby knotwindy » Mon Nov 06, 2017 4:11 pm

Depends if you pull to the same distance or with the same pressure.


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