WA
192 posts
Need some advice from the gurus here: In principle, is it possible to tune a traditional C-kite for more or less bar pressure?
Somebody I spoke to said that by I could reduce the effort it takes to turn the kite by attaching the front lines to the inner leading edge attachments. Is this correct? Is there anything else I could do?
TIA,
Bo
VIC
428 posts
In my experience with C kites, longer back lines = less bar pressure.
What you are proposing is shortening the front lines which is equivalent the lengthening the back lines.
Usually the back lines are adjustable at the leader lines coming off of the bar. I set my back lines longer than my front by about 2 inches as I prefer less bar pressure and flying with the bar against the depower knot.
WA
27 posts
I personally believe that it is minimally possible to tune a kite for more or less bar pressure. The bar pressure that a kite generates is a property of:
Aspect ratio.
Wing tip length.
Wind strength.
Kite size.
Presence of pulleys.
Bow style kite.
Lengthening the steering lines would produce less bar pressure because you are depowering the kite. But in order for the kite to be useable - that is to have steering control as well as little bar pressure there is a given length of steering lines that is essential for correct function. So even if you lengthen the steering lines once you sheet in for control you will experience the same bar pressure as ever. However, in theory if you move the front lines to the inward position there will be less pressure required to cause the kite to pivot in the air (moment=distance from pivot X force applied) thereby theoretically reducing the bar pressure. I also recon that if you were to do this the steering speed of the kite will be reduced as the furthest back position for the steering lines is the fastest turning (for different reasons).
I stand ready to be corrected. This is in my experience and basic physics only.
WA
1802 posts
i don't think your going to change the bar pressure by doing that, the bar pressure is there because your kite is making the power it makes by you flaring the kite ( via the bar pressure) and it pulling against you. some kites will flare more aerodynamically than others and hence require less force , ie, if you have a bow style kite or flat foil, or eliptical tip style kite most of the pull is up or towards the kite and the sides that are not lifting the kite up are small and make little drag and lift , even when you flare the kite, if you have a conventional or deep shaped c-kite, when you flare, all the sides of the c are making pull but not away from you, the pull that they make is just wasted energy or drag so to get a lighter bar pressure from the same sized kites in stronger winds... i recon the only realistic think you may try to do is add a 5th line to help flatten the kite out so in stronger winds, when bar pressure is highest, the kite doesn't tube into a u shape, and loose more energy by haveing longer sides and less middle.
VIC
42 posts
There is something in the 'tune for less bar pressure' theory.
Some kites (for example, I think, the Fuel) have 2 sets of knots for the back lines. The knots that are closer to the trailing edge will require less force to power up the kite than those closer to the leading edge. The trade off will be slower turning response.
Otherwise, kite design can give more or less bar pressure, but there's not much you can do about it.
Cheers
Andrew
1338 posts
It is possible to rig a traditional C shaped LEI with a bridle, using a pulley per side, to reduce bar pressure.
Wipika did this with their original AirBlast range of kites. It is not neccessary to also rig the reverse launch lines but this becomes an option if you sew on two attachment points.
The trade-off, of course, is more bare travel.
There is also a commercialy available bar, from Europe, that neutralises static bar pressure using pulleys at the bar.
Just use it as it is and get some muscle ;-)
