Lines - stuck in the 1980s

[ryoder 1,382]

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The example set of line lengths you give is certainly the system used by PD. I have one question though. How do you know the point at which the lines should cascade? For example, see my attached drawing. Both configurations would give the correct line lengths, with cascades at different points. Seems to me that the lengths given are sufficient to check whether your current lineset is still in trim, but not to manufacture a new lineset. Or am I missing something?

You are absolutely correct. This is a personal pet peeve of mine.

"There are only three things of value: younger women, faster airplanes, and bigger crocodiles" - Arthur Jones.

[mjosparky 3]

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The example set of line lengths you give is certainly the system used by PD. I have one question though. How do you know the point at which the lines should cascade? For example, see my attached drawing. Both configurations would give the correct line lengths, with cascades at different points. Seems to me that the lengths given are sufficient to check whether your current lineset is still in trim, but not to manufacture a new lineset. Or am I missing something?

You are absolutely correct. This is a personal pet peeve of mine.

If you have the old line set, use a steel tape and measure where the cascade is located.
Now you know at which point the lines should cascade.

Look in PPM Vol. I, Page 401 if you don't believe me.

Or you could always contact the manufacture.

Sparky

My idea of a fair fight is clubbing baby seals

[JumpHog 0]

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HMA - Low drag but lasts only 200 jumps

I have over 1200 jumps on the HMA lineset on one of my Xaos-27's and over 600 on the other! Both are still in great shape. I'm having the one with 1200+ jumps relined, not because it needs it, just because winter is a convenient time to have it done.

[billvon 2,396]

>You measure with all the lines anchored to the same point.

I agree with everything in your post. But Sundevil was asking about how to replace a cascaded lineset with a non-cascaded lineset, and you can't just use the dimensions for a cascaded lineset to build a non-cascaded one. You have to make the lines on the non-cascaded set shorter due to the lack of a cascade (which effectively shortens lines on a normal lineset when the canopy is inflated.)

Useless fact of the day - many paragliders use spanwise cascades instead of chordwise cascades.

[mjosparky 3]

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>You measure with all the lines anchored to the same point.

I agree with everything in your post. But Sundevil was asking about how to replace a cascaded lineset with a non-cascaded lineset, and you can't just use the dimensions for a cascaded lineset to build a non-cascaded one. You have to make the lines on the non-cascaded set shorter due to the lack of a cascade (which effectively shortens lines on a normal lineset when the canopy is inflated.)

Useless fact of the day - many paragliders use spanwise cascades instead of chordwise cascades.

OK, now I see your point. What I would do is stake the canopy out on a layout table with the lines under light tension and the "A"s and "B"s stacked in proper relationship to each other and the links on a common anchor. Then measure from the anchor point directly to the "B" attachment point.

Sparky

My idea of a fair fight is clubbing baby seals

[PhreeZone 15]

A's need to be shorter too as well as the C's since under tension they are currently being pulled back a little bit by the tension on the B/D's.

Yesterday is history
And tomorrow is a mystery

Parachutemanuals.com

[mjosparky 3]

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A's need to be shorter too as well as the C's since under tension they are currently being pulled back a little bit by the tension on the B/D's.

Place an awl at the junction of the "A" & "B" after you get the "As" tight and before you tighten the "B"s.

Come on guys this is not rocket science. You are measuring from point A to point B.

Sparky

My idea of a fair fight is clubbing baby seals

[ph8068 0]

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If you have the old line set, use a steel tape and measure where the cascade is located.
Now you know at which point the lines should cascade.

Yeh, it makes sense, it's just not that accurate. For example, the old lines have shrunk and you don't know how much of the shrinkage has occured above the cascade and how much below the cascade.

I can see by this method you'd end up with a couple of inches error here and there. While not much, this kind of defeats the point of putting a new line set on in the first place.

Yes, you are right, I will contact the manufacturer. I was just concerned I was missing something obvious, which is why I didn't do this before.

Thanks,

Paul.

[mjosparky 3]

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If you have the old line set, use a steel tape and measure where the cascade is located.
Now you know at which point the lines should cascade.

Yeh, it makes sense, it's just not that accurate. For example, the old lines have shrunk and you don't know how much of the shrinkage has occured above the cascade and how much below the cascade.

I can see by this method you'd end up with a couple of inches error here and there. While not much, this kind of defeats the point of putting a new line set on in the first place.

Yes, you are right, I will contact the manufacturer. I was just concerned I was missing something obvious, which is why I didn't do this before.

Thanks,

Paul.

You are not missing anything obvious, people are just trying to make it more complicated then it is. Trim spec. are usually given with a + - 1" which gives you some lee way.

Most people do not have the equipment to make a line set so it is always better to get them from the manufacture. They are best made with one continuous line placed under say 10 pounds of tension, marked and then cut after tension is released. This is tough to do without a line table. With the proper equimpment/tools and knowledge most things are fairly simple.

Sparky

My idea of a fair fight is clubbing baby seals