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chrisat13000ft

Hard v soft links?

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I recall PD saying that their Reserve Slinks can tak 70G load. :o



Sure they can :)
70 G's on 1 kg is 70 kg, right?! Try to put 70 G's on 100 kilos and see if it will hold :S
"My belief is that once the doctor whacks you on the butt, all guarantees are off" Jerry Baumchen

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I recall PD saying that their Reserve Slinks can tak 70G load. :o



Sure they can :)
70 G's on 1 kg is 70 kg, right?! Try to put 70 G's on 100 kilos and see if it will hold :S


Deyan:

"The tests:

Performance Designs was not satisfied with releasing our new soft links unless we were absolutely confident in their reliability. We therefore put them through a grueling series of tests including:

- Destruction testing where we pulled the riser/slink/suspension line systems to failure.
- Destruction testing where we subjected the system to rapid onset, high "g force" loadings, up to and beyond the system failure point. This included shock loadings of over 75 g's (12,000 lbs. 4 riser system), utilizing both sport and tandem risers and suspension lines.
- High speed, heavy load, drop tests from a B-25 bomber. These tests are the same tests that are performed on Performance Designs' reserves, in order to meet TSO approval requirements.
- Long term wear testing, on canopies jumped in the field, over an extended time period. This included frequent removal and re-installation of the links tested.

In the tests performed, the Performance Design's Slink survived at loadings beyond the suspension lines and/or riser!

In our testing, the failure point of the system was repeatedly the suspension lines or the webbing attaching the three rings to the riser. In comparison tests, the PD reserve soft link survived tests that caused failures and/or severe damage to #4 and #5 stainless steel links! The PD Soft links not only survived these tests, but showed no signs of damage.

Based upon the results of these extensive tests, Performance Designs is the first manufacturer ever to receive FAA 'TSO' approval for a soft link for use on reserve parachutes!

The Performance Designs Slink is available in two configurations:
- One for main canopies
- One for sport reserves and/or tandem main canopies.

The PD Slink is now available as an option on all new Performance Designs canopies at no additional charge. They may also be purchased in sets of 4 (with installation instructions)."

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Aerodyne was the third or fourth company to certify their re-usable soft links for reserves. FAA TSO paperwork lists their MBS at 3,000 pounds - similar to Maillon Rapide #5 hard links.

I believe that Parachutes de France was the first to certify re-usable soft links under the French EQ system.
Performance Designs was the first American company to TSO their "slinks" under FAA TSO C-23d(?).
Precision Aerodynamics was probably the second American company to TSO "Wrap-It" soft links, while Aerodyne was probably the third.

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This included shock loadings of over 75 g's (12,000 lbs. 4 riser system)



This is the key....12000 lbs divided by 4 risers gives 3000 lbs per Slink.
3000 divided by 75 is only 40 lbs or about 18 kg at 75 G's

It's useless to argue about how much G's you can put on them since the human body in a harness will take no more than 20 before body parts start flying around.
Only Chuck Norris can take 75 G's, but he doesn't need a parachute at first :P
"My belief is that once the doctor whacks you on the butt, all guarantees are off" Jerry Baumchen

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This is the key....12000 lbs divided by 4 risers gives 3000 lbs per Slink.
3000 divided by 75 is only 40 lbs or about 18 kg at 75 G's

It's useless to argue about how much G's you can put on them since the human body in a harness will take no more than 20 before body parts start flying around.:P



The above is obvious, I was just making a point that Slinks are stronger then metal links.

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This is the key....12000 lbs divided by 4 risers gives 3000 lbs per Slink.
3000 divided by 75 is only 40 lbs or about 18 kg at 75 G's

It's useless to argue about how much G's you can put on them since the human body in a harness will take no more than 20 before body parts start flying around.:P



The above is obvious, I was just making a point that Slinks are stronger then metal links.


I wonder...

If they are so strong at the top end of the riser, do we really need all those metal rings and stuff at the bottom end?

Get rig of your three ring ~ get the new & improved Slinky....saves yer life AND walks down stairs! B|










~ If you choke a Smurf, what color does it turn? ~

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The above is obvious, I was just making a point that Slinks are stronger then metal links.



I don't dispute that point, when they are new...
But I don't remember ever being advised to change hard links with every line set, nor do I recall of any Rapide Links failing when properly torqued and maintained. (Soft links loose their strength over time and have failed when left in service too long.)

Not saying I wouldn't use soft links (I do) and not saying hard links are fool proof (we've proven otherwise).

Each have their advantages and limits. Which ever you choose, know your gear.

JW
Always remember that some clouds are harder than others...

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I wonder...

If they are so strong at the top end of the riser, do we really need all those metal rings and stuff at the bottom end?

Get rig of your three ring ~ get the new & improved Slinky....saves yer life AND walks down stairs! B|



Ever seen a 'Harness, Single Point Release' on a military static line rig for dropping your ruck? ;)
"I may be a dirty pirate hooker...but I'm not about to go stand on the corner." iluvtofly
DPH -7, TDS 578, Muff 5153, SCR 14890
I'm an asshole, and I approve this message

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I wonder...

If they are so strong at the top end of the riser, do we really need all those metal rings and stuff at the bottom end?

Get rig of your three ring ~ get the new & improved Slinky....saves yer life AND walks down stairs! B|



Ever seen a 'Harness, Single Point Release' on a military static line rig for dropping your ruck? ;)


No...but I did see a one-legged monkey fall over flinging shit once...does that count? :)










~ If you choke a Smurf, what color does it turn? ~

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That sounds about right. 70 *200 is only 14,000. Our slinks were breaking at 4,000 lb. So in theory 16,000 but remember the load will not be evenly destributed across the risers. And the break lines transfer directly down to the riser.

We've had oppenings where we broke all the lines off a riser... so we broke 9? 1000 lb lines with out breaking the slink. Go figure. Then again on the last flight we broke 3 PD reserve slinks and snapped all the lines on the fourth.

Confuses the fuck out of me. I've simpley resolved to not open at mach 2.

Lee
Lee
lee@velocitysportswear.com
www.velocitysportswear.com

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That sounds about right. 70 *200 is only 14,000. Our slinks were breaking at 4,000 lb. So in theory 16,000 but remember the load will not be evenly destributed across the risers. And the break lines transfer directly down to the riser.

We've had oppenings where we broke all the lines off a riser... so we broke 9? 1000 lb lines with out breaking the slink. Go figure. Then again on the last flight we broke 3 PD reserve slinks and snapped all the lines on the fourth.

Confuses the fuck out of me. I've simpley resolved to not open at mach 2.

Lee



Bolding mine.

I don't think most jumpers have to worry about Mach2. Maybe some of the Anvil Bros :P

And yes, I've read your posts about the rocket recovery systems and understand why you said it that way.
"There are NO situations which do not call for a French Maid outfit." Lucky McSwervy

"~ya don't GET old by being weak & stupid!" - Airtwardo

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