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Anyone every use break cord other than the 80 lbs tape that paragear sells?

I recently cut a piece off and tied it around something to show a freind (that doesn't trust static lines) that it doesn't break easy, but that it breaks, and I couldn't get it to break. I was giving it atleast 100 lbs of force and it wasn't breaking. I ended up tying another peice around a table and sitting down bracing the table with my foot and then pulling on it. I'd say it broke around 150 lbs.

I'm also wondering what type of knot most people use to secure it. Regular overhand or figure eight or what?

P.S. I did some weight tests on cotton twine right after this, and a single strand could hold 20lbs in the air, but if you jerked it around it would break. Two strands held 50 lbs and broke when I jerked it around.

I'm considerring instead of using a big loop little loop 80 lbs break cord, maybe testing 5 ascending loops of double strand cotton twine at TF on video to see what happens.

Shock force or constant pull force? big difference

All the tests I did with my breakcord showed it not breaking when 100lbs was suspended with it, but if you raised the weight about 2 inches and dropped it, it'd break on every attempt. It makes me believe that inertia is a nontrivial factor and I'm not worried since we have just a tiny bit of momentum on static lines.

I have a "question" and would appreciate a response by anyone with experience.

When you do a solo static line, you use breakcord amirite? But this seems kinda dangerous for the following reason: the cord has to be strong enough to pull out PC (and canopy). But if it is too strong, doesn't it damage the point where the bridle is connected with the canopy?

Also, why would you do a SL without a pilot chute? Can't you use the PC in case somehing goes wrong? For instance if the static line doesn't get the canopy out, you're pretty much screwed right?

thx in advance.

from the teeny tiny bit i know... you ALWAYS use your PC when doing SL for the exact reason you mentioned. If it breaks early you still have something pulling your canopy out.

same as droquette:
I would never ever do a static line jump without a pc as a back up.

And you don't use the static line to pull out the pc. You use the brake cord to tye the pc on it's connection point with the bridal (or closer to the pins if it is an ultra low jump) to the object. But you never dismount the pc (or at least I would not...) from the bridal.

dude

your posts are starting to get annoying - do some research before asking the same question that has been discussed to death here before....

80lb break cord is fine

small primary loop with a big backup loop is the way to go

one night after a jump me and 3 other jumpers were having a cofffee at the local Tim Hortons and talking about static line technique and break cord

one of them did not see how a loop of 80lb breakcord will take 160lbs to break because it's a loop

so we got the strongest one of us (a firefighter who is something like 6'2" and 200lb+ all muscle) to try and pull a normal static-line setup till it breaks

we achored it to the table (one of those fixed to the floor jobbies) and he gave it hell

he couldn't break it, so we all agreed that it takes more than 80lbs to break the loop and probably more like 160lbs

so then some of us started getting paranoid about this being too much

so I (at 6'0" and 165lbs, certainly not the strongest person there) stepped up, took the 550 cord tie-off loop, moved it one side of the tie-off point and yanked it as fast and as I could past the tie-off point, the total travel was about one foot

the break cord snapped easily

this is a very informative little test you can do at home too

there is a VERY big difference between what kind of static load and what kind of dynamic load will break the cord


there is no need to re-invent the wheel here

80lb break cord is the bomb, just learn to use it properly

cya

PS - re-reading your post, it seems you tried to break a loop of break cord and expected it to happen at 80lbs, it happens at 160lbs, because a loop is two strands together! If you cannot get yourself to understand this, consider sticking to sports that do not require as much understanding as BASE does.

Dave: As 980 pointed out, there are two sides to the loop, so it breaks at about 160 lb. My understanding is thus: If you put 80 lb of tension on the cord, that's 80 lb per side, which means the total force between the anchor and the bridle is 160 lb.

For the knot, use a surgeon's knot. Back it up with as many overhand knots as you like.

Vincent: The bridle attachment point is much stronger than a loop of break cord. It's a good idea to check the attachment point regularly regardless of what kind of jumping you do, but unless something unusual is happening, there should be no problems.

I have done one static line jump with no pilot chute. We were jumping a 111-foot span and the canopy barely had time to fly. I thought if I removed the PC, it might help, and also thought it couldn't really be much of a backup from that height. There was no measurable difference in canopy flight between jumps with/without the pilot chute. DW later pointed out that the most likely time to get a premature break is actually fairly late in the deployment sequence, and there is a good chance that a 48" pilot chute would help even on very low jumps. So I don't think there's any reason to jump without one.

Michael

I don't think it will damage the bridle attachment point of your canopy. The forces just aren't there unless you've misrigged something.

However, if it did, it still wouldn't be dangerous. By the time that part of the system could take a big load, you'd already be at line stretch. Even if your attachment point was damaged then, you'd still have a functioning parachute over your head.

Gear maintenance issue? Maybe, but I doubt it. Safety issue? I don't think so.

hey you know more about sl than i thourght.. brig your gear end of feb as you visit Nikolaj
Ill take "a dance" whith you show you arround,ask nikolaj i have some nice fun arround here

looking forward but first another trip on pain and drugs..

if your attachment point on your bridel is going to break on a BASEjump there can be 2 faults..

#1 bad gear maintain,which means you jumped equipment that has been dammeged already

#2 your loops are so tight that you cant open your harness,if its that tigh you will die anyway(i dont know how that should happen,but i guess someone gonna prove it one day..)

I think its more likely that you gonna rip your topskin than ruin your bridel..

ALWAYS USE PC AT SL`S

A friend of mine had a bridle hang up on a static line jump. The opening and canopy flight were normal except in hindsight he said the line stretch shock was a little more than he was used to. He didn't even know it happened until the next day when he looked at his canopy and there was no bridle attachment point. Instead there was a very neat rectangular hole in the top skin of his BlackJack.

I've seen a canopy have the entire center cell topskin ripped out. It was a Lightning with a modified lineset on it, so non-reinforced BASE-style attachment point. Exit was a 120' bridge pylon. I had a solid 5 seconds under canopy with my vented Fox. The other guy had about the same amount of canopy time but flew 1/2 as far as I did and the canopy stalled and partially collapsed when he flared.

Wow. That's stunning.

Did he ever figure out what happened? Was there some kind of misrigging on the static line? Maybe the bridle snagged on the object?

He went to the object the next day and couldn't find the bridle or pilot chute, so there's no way of knowing exactly what happened, but it's almost certain that the bridle and/or pilot chute snagged on the object. The tie off point was a rail recessed about 5 feet from the exit point. Between the tie off point and the exit point there is metal grating. Our best guess is the pilot chute got dragged along the grating and snagged something. The same exit point and tie off point had been used successfully in the past.

Marty said the bridle attachment point was designed to fail at 400 lbs and leave a small rectangular hole like that.

I'd be pretty sure that the bridle snagged the object. I had a PC snag on my last SL jump and resulted in torn PC but the topskin and bridle attachment point were fine. I'd guess that in case of PC snag the PC will be ripped to pieces but it will not affect the canopy.

http://sunmutsi.ufufreefly.com/tattivaurio.jpg

i had assumed something along those lines... nice

Why not tie a runner of 900 Dacron or climbing rope or something to seperate the bridle from the object?

This also leads me to believe the breakcord/bridle attachment point was directly below the PC instead of down a couple feet...I've been taught (by Todd @ Apex)to attach the break cord to the bridle as close to the canopy as possible without the risking canopy hitting the object on extraction.

I was passing along what I heard from my friend. Correction from someone who would know:

"The Bridle attachemt is held on to a BlackJack with four bartacks, each one is in excess of 400 lbs."

That's because I static line stuff you would probably freefall... :-)

unless i misunderstand what you mean, that would work, but you'd have to climb back up and get it to not "leave a trace".

that dosnt mean we cant have fun

pm in a min or two

would a direct bag be better in this case at 111'.

I like the surgeon's knot. Thanks Michael.

I just realized that since it's a double loop the force applied to it is divided between the two strands. And the knot reduces the stength a bit. Anyone know the average percentage of strength lost on a surgeon's knot?

Has anyone ever used anything other than 80lbs break tape?

Yes, the knot should in theory be the weakest link. Don't know about a surgeons knot for strength but on a climbing rope the figure eight knot is one of the strongest at 80% of the rope's weight/shockload rating.

So, would you not then expect break-cord to break at the knot!??! All the times I have found or seen the break-cord after a jump, it never seems to come apart near the knot. Any thoughts?

Also, I have heard as someone mentioned earlier about tying in lower down the bridle. I have always used the the PC loop with an extra piece of static 5or6 mm climbing cord to actually attach the break cord to. IN my thoughts, there shouldn't really be anymore shock load to the canopy/system even with an extra 3-4 feet of bridle because the break-cord will still break at the same amount of force. Any thoughts/explanations on this or really good reasons to tie into the bridle lower!!?

Thanks

I have used fishing line, electrical tape and cotton twine. I know people who've also used condoms, plastic shopping bags and various other kinds of line.

Honestly, I think I'll stick to break cord until someone demonstrates that one of the alternatives is clearly better, which hasn't happened yet.

When they were doing the demo jump at the Superbowl, Apex had to do a bunch of drop tests to satisfy the various powers that were involved in the event. They found that tying break cord at the end of the bridle had a noticeable rate of premature breakage (if I recall correctly, Jimmy told me it was 1 in 20 or something), but that tying the cord halfway down the bridle reduced the premature breakages to the point that they were unable to create any with repeated test drops. They created bridles with sewn in loops to static line from, about halfway down, just for that demo.

An easy way to tie in partway down is to put an overhand loop in your bridle and tie to that.

Probably because the jerk force increases due to the greater distance of the drop before tension.

Good to know. I mean, I heard different things from different people as you always will in this activity. I do always use the double break-cord method since premature breakage was obviously a concern at S/L heights. I must say one of the main reasons I have not done it that way is management of the bridle/ PC. Having seen others do it this way and lots of videos and some horror stories I didn't like the looks of it soo much. I liked having the PC right up at the S/L, bridle s-folded in my hand so the PC can't catch wind, dance around swinging 4 feet of bridle with it etc... I will however try it next time. I like the idea of having a bridle with sewn in point on it.

the knot is not the only stress concentration the cord sees

it also sees stress concentrations at both ends where it is attached to your bridle and the object


how you choose to attach it to the object and your bridle will determine how high those stress concentrations are and most likely it will break at the point of the highest stress concentration

unless of course there is some material defect in teh cord, in which case it might break there instead

which is why not only do I always use the double loop method, I always use different colours for each loop, to ensure I don't get both loops from the same batch of breakcord, or even worse, from the same area on the same batch of breakcord...

I have found that using 550 cord to tie to the object and a small rapide link to attach to my bridle, that even with an overhand knot the breakcord doesn't break at the knot.

in addition I have seen a really smart carry-with you set-up that carries EVERYTHING you brought, away with you...

One of Nick's carry with you does exactly that, it carries even the broken cord that broke. However chances are the cord won't stay on the object anyway and if you are a tree hugger, cotton is biodegradable so you should go and find the TG rubber band!

The surgeon knot strength reduction is about 20-30% for those interested so the overall strength of a break cord loop is between 112-128 LBS. Also the 80 LBS rated strength is the minimum strength not the maximum. Also cotton is hydrophilic so its strength will vary according the humidity.

And d_goldsmith, you really seem to love posting mindless threads on topic that have been beaten to death. The I is not the place to learn BASE!

A S/L jump is the most mindless thing to do however people still kill themselves due to miss-rigging. Before you go and kill yourself seek advice from real experienced BASE jumpers not virtual ones. And if you want to keep the saga of mindless posts please learn from Maggot, at least his threads are funny as shit and he does not try to learn anything in here.

I just got some great advise from "real experienced base jumpers" right here on "the I". Isn't that one of the greatest points of this forum?

sure, except that someone advises you, and then you receive advice.

That is some very interesting piece of information there. One thing popped up my mind though, if you tie the breakcord halfway down the bridle, how do you control the rest of the bridle (the upper part) and the PC ? Do you just let them hang below the exit ? Doesen't that have very high risk of bridle entanglement with the object since bridle is making a "loop" at the exit point ? That of course is no consern if exit point is "clean" and overhung (like the one in superbowl) but if you are SL'ning from cranes, A's ect it could be an issue. Any thoughts about that ?

The chances of the bridle and/or PC entangling the object are much, much higher using this method. I really do not like it regardless who and where it was used. I know of at lest two incidents where this method could have resulted in two fatalities. TowerTopper can chime in hopefully sharing his view on this (one of the two incident).

You could stow the remaining bridel with a rubber band to keep it together.

edit:
when I say stow I mean to just s-fold the remaining bridel and keep it together with a rubber band...

You could of course but wouldn't it be better to make a custom length (shorter) bridle for SL-purposes (and possibly ultra low FF) ? Then you wouldn't need to worry about the excess bridle.

Would it? Wouldn't that put the tail of the canopy even closer to the object and for what benefit? The purpose of the bungee isn't to short-line the bridle, it's to manage it until it is time to pay out in the deployment sequence. Also, what happens if the static-line breaks prematurely and you are towing the pilot-chute in your burble with a really short-bridle at very low airspeeds?

I was referring to a case where you tie the breakcord halfway of the bridle, for example the Superbowl jump that Tom A commented on earlier. I don't see how normal length bridle in that case is paying out on deployment sequence if the breakcord is suppose to hold (almost) as long as you have bottom skin inflation.


The subject of the existence of burble on low airspeeds has been discussed pretty thoroughly here and I agree that there are different views about it.

I use normal lenght bridle, also on SL but the idea of a shorther bridle came up to me when Tom told the details of Jimmys tests for preparing the superbowl jump. I could think that shorter bridle would have the benefits of "breakcord halfway down the normal bridle" -setup but the jumper would not have to worry about "stowing" the excess bridle and getting it possibly entangled with the exit point. I agree that using a shorter bridle would have the downside of the PC being caught in the burble in case of breakcord premature break but then again if the breakcord (which is halfway down the bridle) breaks prematurely and the "excess" bridle is stowed away with bungee wouldn't there still be a risk of PC getting caught in burble since the bridle is actually shortened by the bungee ?

Yah, but it takes a lot less force to pull the bridle out of a bungee than it does to get you to line stretch. cpoxon must not have read the whole thread, but I was going to write the bungee idea until I read that he had coverred it.

When I static line I like to attach the SL as close to the shrivel flap/pins as possible while still allowing me to stand-up at the exit point. In fact, I'll bring several different lengths of static line to still allow me to attach close to the pins and still stand up. (ie - If I'm standing on a platform and tying off to the platform the SL needs to be longer than if I'm tying off to a rail that's right behind my back.)

What to do with the extra bridle? The same thing I do on a handheld jump. I s-fold the bridle up to the pilot chute in my hand and execute a throw-and-go on exit. I pitch up and out to keep the bridle and PC away from the object yet ready to inflate if the break cord breaks prematurely.

Why do this? The shorter the static line, the lower the shock-loading applied to it at SL stretch. It probably means more with a shrivel flap than pins, but at heights lower than 150 ft, anything I can do to avoid a premature breakage of the break cord, I'll do. Also, pitching the PC up and out puts it above and away from the object.

I have video of this technique and the PC is inflated VERY quickly after the break cord breaks. Of course, canopy is inflating at the same time, but it sure looks like that PC is ready to do its job. (This was a 143 ft B with a 50 ft palm tree directly below and a 90 right required for landing.)

you wont have a burble at werry low airspeeds..(my belive)

I can see serval places were i could/might would use a shorter bridel,i however hasnt done it yet,as you stated above what bennefit should it give(besides perhaps ULTRALOW FF-another dissusion)on a SL jump..
IF the object is so LOW that you need the extra few feets as safe magen,your in the wrong spot and shouldnt do the jump..

How low do people think of low as they speak SL?

Personaly im below 130ft or so if i really want to change my config on my gear as of right now..
doing a regular SL off 140ft will give you "plenty"(enough if you know the envioment) time to pop toogles and even do a slight turn and still land safely on hard ground..(my last jump off 140ft in strong headwind-sl off a S gave us 4-5 secs in the air(inkluding falling),we poped toogles and landed at grass just below exit point,off the same object in more ideale winds i had even more time..

IF you want to jump in the low end you better be thinking fast and feel good about your timeline from exit to landing,and be ready to hold on to your arse if somthing goes wrong,things happens really fast in that envioment, i still think my 0.78 loaded Vented Flik flyes as fast as my old xfire 99,when im flying down there,i have the same amount of time if not less to correct if i need to..

Craig,the above aint stated to you or respond to you personaly its just my humble oppinion,take it whith a grain of salt

It depends. A direct bag will get you open higher, but there are a couple of things I really like about s/l:

First, it is consistent. There's no chance of the bag being held a bit cockeyed. If something does go wrong, it's very likely a mechanical failure of some sort. Certainly, I won't leave behind a bag holder who will always wonder if he did something wrong.

Second, it's quick. If I tie the break cord onto a karabiner which is attached to a short leash beforehand, I can quickly get out of the vehicle, throw the leash around the railing, climb and jump.

If I was going sub-100, I would consider a direct bag, but obviously I'd need to have done a lot of practice with the bag holder beforehand.

Michael

Absolutely 980… Thank you for your post…

Dave Goldsmith – You have numerous resources up here to answer your questions… If you would have asked me, I would have told you about dynamic force… If you drop a 5lbs weight at desk high level, it will break 80lbs cord.

Again, as 980 said, do your research before asking such basic questions…

Michael

My bad... The actual experiment that I was taught is below:

“ Conduct a simple experiment to demonstrate this dynamic force. Attach a 9 foot bridle to a fixed point (the ceiling). At the bottom, attach a 5lb packing weight. The two are attached by a 80lb break cord. The 5lb weight is dropped from the ceiling and allow to freefall 9ft. The 5lb weight will generate enough dynamic force to break the 80lb break cord.”

Again… Dave – these are basic principles you should know before BASE jumping…

Michael

Not to mention, here are the 612 search results that talk about BASE static line jumps on this site:

http://www.dropzone.com/...p;sb=score&mh=25

It took me 5 seconds to pull these via the built in search on this site...

Michael

  Yea, that would have to be a very tall desk..

From 9 ft it should take about 0.75 sec to fall, reaching 24 ft/s velocity with a momentum of 120 lb ft/s. Because it's deccelerated quickly(over a very short amount of time) it generates more force on the cord (more than 160 lbs) than just it's momentum.

Or something like that...

Exactly the point... This is where the knot comes into play, because you can prematurely break the cord with the wrong/poorly done knot.

i dono if it has been covered yet,

but any nylon woven or twisted rope or cord will lose 10-40% of its strength when knotted.
the loss goes up with the diameter of the rope being used, and it will go down with the amount the rope or cord stretches.

break cord is very low stretch relative to its similar diameter OR similar strengh nylon. so a the same knot would weaken the break cord more than say, a suspension line.

sigh... i need to sleep. or cut my cast off.

People who SL shouldnt have a tight harness,that requires more than 80lbs to open i thing its half is like 40kg? am i right?
try do a pull test on your bridel whith a simple fishing weight.. my spectra loops aint loaded more than 3,5kg(at most)(if above is correct= 7lbs)to pop open the harness...

I however ALWAYS use a backupcord in case of premature break..

My harness is trimmed to be used at low frefeefalls thats why its so easy to pop open

NOTE: by using spectraloops and easy to pop harness,your in dangerzone if you take the same rig on a terminal(dunno why any would..).

> re-reading your post, it seems you tried to break a loop of break cord and expected it to happen at 80lbs, it happens at 160lbs, because a loop is two strands together!
——————————————————————————————
Let's make it clear once for all.
A 80 lb - 36 kg break cord will break at 80 lb - 36 kg when "deployed" in a "perfect" environment such a laboratory with one single strand of break cord in the "jaws" of a dynamometer.
When we use break cord we are NOT in a laboratory and so we use it in a loop configuration, which loop configuration is going to break at 160 lb - 72 kg, again when measured in a laboratory environment, i.e., with a long loop with terminal ends sewn together in a long seam and same loop placed in the proper fitting of same dynamometer.
When we SL BASE jump, we do NOT have such a proper fitting, moreover we don't have up there a sewing machine, so, in the end, we do a surgeon knot in order to be able to close the loop and "surgeon knot" in order to minimize the "knot degradation factor".
Any cord/rope/whatever is going to have its own BL (Break Load) diminished every time a knot is done on it.
According to various books/text (Dan Poynter manual included), we can expect to have the BL diminished of 40% when a knot is done (or, new BL is 60% of thoretical BL).
So, given for granted the theoretical break load of our break cord is 160 lb - 72 kg (we are using it only in a loop configuration), in the end we come up with an actual BL of 0.6 x (160lb-72kg) = 96 lb - 43 kg.
To make short a long story: when we use a 80 lb - 36 kg of break cord in our SL BAS Ejump, we can expect that we break the loop of same break cord at 96 lb - 43 kg.
Or, said in another way, closing the loop with a knot "deteriorates" the break cord BL in a way that in the end we have a real BL which is nearly the same as the theoretical single strand BL (it should be double but returns to the "original" value because of the knot).

I ran a test of paragear's 80lb break cord last night, and I'm still here. I will continue testing it until I find myself dead or hanging from an antenna by my bridle.

P.S. If you don't solve the mystery of the break cord, you could always resort to go-and-throws and/or higher objects

P.P.S. I agree with 980.