Line Lenghts, especially pertaining to 5th line systems

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Line Lenghts, especially pertaining to 5th line systems

Postby cedralpass » Mon Aug 08, 2005 7:05 pm

I have the 2004 spitfire 14m and the 5th line conversion kit. The arc line looks right, and extends a little longer than the wing tips, for trimming. the line lenght is 27m.

I have been flying it for a while now, however, a few experienced people on alameda beach have said the kite doesn't seem to fly right. They think it looks flat, like my center line is too tight, and the outer back lines seem to tight as well.

I decided to measure the 3 front lines last night. I put the outer two front lines onto nails. They matched up. The, "5th line",center line could not reach the nails. I then got out some rope, and made an extension. I measured the distance of the gap, and I have found a 32 inch gap. My questions are:

Should all 5 lines be equal from the bar when sheeted all the way out? Should my center line be extended to the length of the other 2 front lines?
Shout the Front and Back Lines be the same length when sheeted out? ( I think the back lines are a little longer. 3-5 inches than the front when sheeted out)


I put up a picture: http://www.300kbps.com/geoff/photos/kitelines.gif

Thanks in advance,

Geoff
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Postby kitekarl » Mon Aug 08, 2005 9:54 pm

Your 5th should have a couple inches of slack in normal flying and should be taut in the gusts. Rig it a bit over slack and re-rig an inch or 2 in every time you fly it until it feels taut and responsive. You'll know you've gone too far when it's always taut and doesn't hold consistent power.
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Postby sflinux » Wed Aug 10, 2005 12:02 pm

Geoff,
The first thing I would do is tune your 4 line bar. Normally, when the sheeting system is fully let out, and the chicken loop is free (not hooked in) at this point you would want all four lines to be the same length. To do this, tie a sling (with a knot) to a tree, post, etc and larkshead all four lines to to the knot on the sling and pull your lines taunt. Your bar should be 90 degrees and all lines should have identical slack (or lack of) I like to test my front lines first and make sure they are the same length. Then I test my rear lines and make sure they are the same length. Then I test all four lines to make sure the front and rears and the same length. Once this is all cool, then throw a 5th line into the equation.
For the 5th line, ideally you want the 5th line to be the same length as your front lines. This makes it nice if you want to use one bar with multiple 5 line kites. So I would use the sling on the post and tie your front lines and the 5th line and tune the 5th line so it is the same length as your front lines. You definately don't want it any shorter than your front lines. Better for it to be the same length or slightly longer (little less droop for the 5th line when taunt (when pulling on the bar while tied to post, tree, etc)).
Now that your line lengths are all the right length, now look at your shift line (arc line, 5th line pigtail, whatever you want to call it). Ideally you want to have a shift line with multiple knots (like 5). You would want the middle knot (this is your kite's arc length) to be the same length as your front pigtails (when kite is inflated and shift line is pulled to middle of kite). Having multiple knots make it nice to fine tune the 5th line. For gusty days, you want to use a knot closer to the leading edge. For light days, you want to use a knot closer to the bar. You want to experiment with your knots to see which one works the best (it's hard to precisely measure the shift line length). And it also gets complicated if you are one to use different knots on your leading edge (front) pigtails.
I personally am not impressed with commercial retrofit kits. I've seen a lot that have the 5th line too short like you've observed.
You can find an excellent tutorial on making a 5th line at www.herchers.com
I also recommend keeping your existing 4 line leash and just have the 5th line there to pull for assisting relaunches.
You mentioned that your rear lines are 5 inches longer when sheeted in. They should be the same length when sheeted out. I define sheeted out so that your sheeting system is let all the way out. Do all your measurements not being hooked into the chicken loop. Understand how your sheeting system works. Pulling in on your sheeting system effectively shortens your front lines (or lengthens your rear lines depending on how you look at it). Hooking in to the chicken loop and pushing out on the bar also shortens your front lines (or lenthens your rear lines depending on how you look at it.)
-bric
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Postby sflinux » Wed Aug 10, 2005 12:03 pm

Geoff,
The first thing I would do is tune your 4 line bar. Normally, when the sheeting system is fully let out, and the chicken loop is free (not hooked in) at this point you would want all four lines to be the same length. To do this, tie a sling (with a knot) to a tree, post, etc and larkshead all four lines to to the knot on the sling and pull your lines taunt. Your bar should be 90 degrees and all lines should have identical slack (or lack of) I like to test my front lines first and make sure they are the same length. Then I test my rear lines and make sure they are the same length. Then I test all four lines to make sure the front and rears and the same length. Once this is all cool, then throw a 5th line into the equation.
For the 5th line, ideally you want the 5th line to be the same length as your front lines. This makes it nice if you want to use one bar with multiple 5 line kites. So I would use the sling on the post and tie your front lines and the 5th line and tune the 5th line so it is the same length as your front lines. You definately don't want it any shorter than your front lines. Better for it to be the same length or slightly longer (little less droop for the 5th line when taunt (when pulling on the bar while tied to post, tree, etc)).
Now that your line lengths are all the right length, now look at your shift line (arc line, 5th line pigtail, whatever you want to call it). Ideally you want to have a shift line with multiple knots (like 5). You would want the middle knot (this is your kite's arc length) to be the same length as your front pigtails (when kite is inflated and shift line is pulled to middle of kite). Having multiple knots make it nice to fine tune the 5th line. For gusty days, you want to use a knot closer to the leading edge. For light days, you want to use a knot closer to the bar. You want to experiment with your knots to see which one works the best (it's hard to precisely measure the shift line length). And it also gets complicated if you are one to use different knots on your leading edge (front) pigtails.
I personally am not impressed with commercial retrofit kits. I've seen a lot that have the 5th line too short like you've observed.
You can find an excellent tutorial on making a 5th line at www.herschers.com
I also recommend keeping your existing 4 line leash and just have the 5th line there to pull for assisting relaunches.
You mentioned that your rear lines are 5 inches longer when sheeted in. They should be the same length when sheeted out. I define sheeted out so that your sheeting system is let all the way out. Do all your measurements not being hooked into the chicken loop. Understand how your sheeting system works. Pulling in on your sheeting system effectively shortens your front lines (or lengthens your rear lines depending on how you look at it). Hooking in to the chicken loop and pushing out on the bar also shortens your front lines (or lenthens your rear lines depending on how you look at it.)
-bric
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Postby cedralpass » Wed Aug 10, 2005 12:49 pm

Thanks Bric,

This is great. I'll definatly check the lines this way.

I made a mistake in my diagram and text above. I meant to say the back lines are 5 inches longer when sheeted OUT. So, ill definately tune to make them even.

Thanks again.

g
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