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freefaller76

Spectra/dacron lines

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Anyone who doubts that suspension line stretch is a factor in reducing the opening shock felt by a jumper, should make a bungee jump...only replace the normal stretchy bungee cord with a stainless steel cable. What's going to happen when you hit the end of that steel cable? Your leg is going to be torn off, that's what. Now remember, Spectra line stretches about as much a steel cable.

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Anyone who doubts that suspension line stretch is a factor in reducing the opening shock felt by a jumper, should make a bungee jump...only replace the normal stretchy bungee cord with a stainless steel cable. What's going to happen when you hit the end of that steel cable? Your leg is going to be torn off, that's what. Now remember, Spectra line stretches about as much a steel cable.



I completely agree with that.

How much does Dacron line stretch? How much of an impact does that make on opening with 10-15 feet times 12 lines (not counting B and D lines)?

Along the same lines (pun inteneded), I wouldn't bungee jump with Dacron line either.

Derek

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My tests show up to a 300% increase in opening shock felt by the jumper using Spectra vs. Dacron suspension lines. It is not always that much different. It depends on how quickly the force is applied...and canopy makers have done a good job of designing canopies that open slowly enough to allow the routine use of Spectra. However, when a rare hard (quick) opening happens, Spectra lines will definitely make it hurt more.

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My tests show up to a 300% increase in opening shock felt by the jumper using Spectra vs. Dacron suspension lines. It is not always that much different. It depends on how quickly the force is applied...and canopy makers have done a good job of designing canopies that open slowly enough to allow the routine use of Spectra. However, when a rare hard (quick) opening happens, Spectra lines will definitely make it hurt more.



Ah, Bill, what do _you_ know? ;)

Seriously, though, 4x pain on a slammer sounds really icky. But Dacron lines doesn't impress the girliez. Easier to stow IMO, though.

-=-=-=-=-
Pull.

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My tests show up to a 300% increase in opening shock felt by the jumper using Spectra vs. Dacron suspension lines. It is not always that much different. It depends on how quickly the force is applied...and canopy makers have done a good job of designing canopies that open slowly enough to allow the routine use of Spectra. However, when a rare hard (quick) opening happens, Spectra lines will definitely make it hurt more.



Braided nylon has a minimum elongation, stretch, of 20% which can be 100% greater than dacron. But braided nylon is not cool.:P
My idea of a fair fight is clubbing baby seals

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...only replace the normal stretchy bungee cord with a stainless steel cable. ...



The point about Spectra's modulus being the same as a steel cable is well taken, but bungee jumping and parachute deployment are apples and oranges. Replace the bungee cord with Dacron in the example and the same thing will happen.

Bob

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