Non-cascading lines

[Harksaw 0]

I have been wondering if there are any benefits to non-cascading lines. I would think that they would cause more drag. Is it because you can't cascade HMA lines? I also noticed that my reserve has four noncascaded lines (inner most D lines) Maybe they are stronger?

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I started skydiving for the money and the chicks. Oh, wait.

[FreeFlyFridge 0]

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Technora-Leinen
Die Technora-Leine (früher HMA) ist sehr längenbeständig. D. h. die Kappe fliegt, innerhalb der von uns vorgegebenen Lebensdauer, in der richtigen Trimmung. Auch die Abriebs- und Knickfestigkeit wurde durch die Technora-Leine im Vergleich zur reinen Aramid- oder Kevlarleine deutlich verbessert. Unsere Leinen werden direkt (ohne Kaskadierung) an den Attachement Points befestigt, was zum einen eine höhere Profiltreue, aber auch eine einfache und kostengünstige Wartung gewährt. Jede Leine kann einzeln, ohne Nähmaschine gewechselt werden.

That´s what I´ve found on the german web site of HighPerformance Canopies (manufacturer of the Nitro) who used the line as the first company, as far as I know.

Ok I´ll try to translate that, lets see how that works. It´s roughly, so if anyone who can translate it better, feel free to do so. here we go:

Technora Lines (formally HMA) do not shrink, so the canopy will fly in the the correct trim for the lifespan given by us. Also they withstand abrasion and folding significantly better than Aramid- or Kevlarlines. Our lines end directly (without cascades) at the attachment points resulting in a better profile of the canopy, as well as for an easy replacement and less maintenance costs. Each single line can be changed without using a sewing-machine.

And here´s something from the Precision Aerodynamics web page they manufacture the Nitro in license of High Performance Canopies for the US market it´s called the Nitron.

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The HMA line is very thin, and the reduction in parasite drag is clearly evident to anybody who jumps the canopy. Line drag is a significant factor in several elements of flight, and any reduction to drag in any wing is beneficial to higher efficiency flight. The HMA line wears better than Vectran, has the strength of Spectra, retains its original trim like Kevlar, and has all of the good qualities of Dacron without the bulk. HMA line is available in 352, 440, and 946-pound tensile strengths, and the braided diameter is smaller than either Spectra or Vectran. Our experience during the past two years indicates that HMA line not only packs smaller, it also tolerates the slider's friction quite remarkably, while at the same time retains its linear stability as well as Vectran.

C-ya
Jens

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ROCK ON,.....HARD!
Proud European!!

[diablopilot 2]

Cascade Pros: Less bulk packing, less parasitic drag in flight.

Cascade cons: More load per line, harder to build, more pronounced changes as the line goes out of trim.

HMA is very small and finger traping it is a pain in the ass, so it is usualy not cascaded on canopys. It can be done however.

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You're not as good as you think you are. Seriously.

[mollusc 0]

Do anyone know if it is possible to change to non-cascading lines on a canopy that originally has cascaded lines?

[rigging65 0]

If it's a main, you can re-line it yourself...but don't expect any help from the mfg...they will most likely tell you not to do it in any manner other than the way they designed the lineset.

It's really not all that big of a deal to build a line set at home, but it does take time.

Of course, if the mfg. recommends against it, you might want to ask "why"...they may actually have a reason other than "because we haven't done it, so you shouldn't".

my $.02

"...and once you had tasted flight, you will walk the earth with your eyes turned skyward.
For there you have been, and there you long to return..."

[riggerrob 613]

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I also noticed that my reserve has four noncascaded lines (inner most D lines) Maybe they are stronger?

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Yes, since the bottom skin of the center cell takes the first jolt of inflation, it is the most heavily-stressed part of the canopy.
Not cascading the A and B lines on the center cell effectively doubles the strength of those lines.
Incidentally, this concept was invented by canopy formation jumpers, then back-loaded to reserve design. Oh, wait a minute, most of the reserves designed during the 1980s (Raven, Fury, etc.) were just slightly modified CF canopies.

[ZigZag 0]

line-sets that are non-cascaded, probably around
+/- 80 jumps! But for competition swooping, it is clear that PD is able to milk every advantage. I doubt that we will see cascaded Technora line-sets in the near future. Bartacking Technora also requires a
modern electronic bartacker, as conventional mechanical bartackers are not precise enough. In addition, the bartack most likely weakens the material somewhat.
As to the underlying principle of suspension lines, there should be no reason why any modern canopy could not be converted to a non-cascaded system using Technora. I've seen it done on a Stiletto, with positive comments from the pilot. But once again, mfg's might not like people changing their configurations and specs.

[diablopilot 2]

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To my knowledge, and someone please correct me, P.D. is the only mfg to bartack and cascade Technora(HMA), and only on canopies that are being used for competition swooping.

I believe that Precision has done it for TJ Lungren (forgive me if I spelled his name wrong) for the excat same purpose. The life is reduced, and only relly showes any benifit to the top pilots.

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You're not as good as you think you are. Seriously.

[alan 1]

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Yes, since the bottom skin of the center cell takes the first jolt of inflation, it is the most heavily-stressed part of the canopy.

Derek has done some testing with canopies and reports that a canopy with the ribs and top skin removed does not inflate. That would seem to suggest that the bottom skin does not take much of the load at all, but rather it is transferred through the loading tapes to the top skin. My limited experience tends to support that notion, since the canopy damage I have observed due to hard openings has been heavily in favor of tears/rips in the top skin or broken lines, even tears in the ribs, not tears in the bottom skin. What am I missing here?

alan