Basejumper.com - archive

I did a quick( because a;my computer time at work is limited, and b;I'm a lazy bastard.) search and didn't find anything so I'll throw this out there. What kind of usual or unusual signs of wear and tear do you guys/girls see on your canopies from frequent static lining? I check the usual stuff; bridal, bridal attatchment point, top skin, bottom skin, ribs, line attatchments.......am I missing anything?
Kinda thinking the center b's and c's are taking the bulk of the force needed to break the sl. ??

In a S/L set up the break cord breaks at around 80LB so usually there should not be more than 80LB of force that is applied to any component of the rig.

In constrast a 28" Z-po PC will pull with a force of 160 LB at terminal. I assure you that BASE canopies are built much stronger than Skydiving mains...

Bottom line: no sweat unless you are doing something very wrong with your S/L set up.

 

Nice reading.

Funny thing is that when my Viper blew up due to a 200kts deployment no line broke but the bridle attachment point ripped off the canopy and three cells ripped at the bottom skin fabric. None of the stitching ripped.

You probably just did it wrong.

 

Also remember that a BASE canopy and a skydiving canopy like Nick's Viper may have variances in construction and deployment.

I'm not sure how to explain this in a way that will convince all the skeptics, so next time I see you, please ask me to demonstrate:

-break cord is rated at 80lbs break strength
-standard static line set up uses 80lb break cord tied into a loop with a surgeon's knot
-this loop requires a breaking force of 2 times the breaking strength, reduced by a factor for the greatest stress concentration in the system (the knot you use, the link you use, etc.), which generally works out to just under 160lbs on the bridle

and no, this doesn't mean that this method will suspend you if you weigh less than 160 lb

cya
sam

I just want to confirm this as well, having tested this using a tensile tester. We averaged 158 lbs.


Unless you were to carefully lower yourself and very slowly increase the force on the break cord. You know this of course, I just felt like pointing it out...

Didn't someone in this thread do some real testing that shows that the breaking strength of a standard static line set up is around 100 lbs? (Or did I read it wrong?)

You start with 80 lbs, loop the cord giving you 160, then subtract that 40 percent loss from tieing a knot in the loop to get 97 lbs give or take.

Lou

Yeah I follow the math but as Lou said there is a reduction in strength due to the knot.

Even if the overall strength is 160LB, it is about the same as a 28" PC at terminal so again I would not sweat over it.

As for my mishap with my Viper I guess skydiving main canopies are not supposed to be deployed at 200Kits! The canopy had no more than 150 jumps total and it was in great shape. Remember that BASE canopies are much more overbuilt than SD mains yet I would not delpoy them at 200Knts

i replaced a bridel so far but that were on a hang up whith the carry on sl,before i started to ude the "cut away cord" he he
did i ever tell i love that set up..

Thanks guys. Hadn't called any manufacturers to see what people were telling them. Just curious to know if anyone had expierienced any failures due to frequent sl'ing. I'll give Todd or Jimmy a call.

Or Martin Tilly at Asylum Designs. 530-823-5222
He knows a little about BASE jumping too.

that were werry humble.. he knows sh!it loads of stuff,only bad thing about him is that he didnt make a jump whith me this summer