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Hey,
i m juming a ultralite canopy, with dacron400 lines, i heard one of the manufacturer of a specific ultralite canopy is not selling anymore those 400dacron because of a fatality due to broken lines.
Heard also about an incident (it will appear soon here) without injury, with broken lines at opening....
What s your point of view? Will appreciate a professional rigger point of view.
pierre

Thats 2 in just under a few days...

i have two lite weight rigs and my trusty troll after hearing of issues with lines and lite weight rigs, i have a huge decision...

hopefully no one else has issues with lines snaping

Be safe

hi pierre ,

why did you buy originally an ultralite canopy ?

what kind of jumps do you do with this specific equipment ?

does your rig come with badass hardware and 3 ring system ?

Great thread starting!

is ultralite a need for hikers( i dont want to hear anything about aerodynamics and low profile) or
just fashion in basejumping ? i am very concerned since i m not experienced at all .

I choose light weight canopy cause:
Jumping in france, some exit are a bit long access, ok not all of them... and it s easier when you have 2kg less in the backpack, even when it s a 20min access.
Also that s my 2nd rig, first one is a regular one.
no i don t ask for 3rings.
And also because basejump market offer it...

I witnesses these 400 lb lines break a few days ago, they broke just below the cascade of the center A and B lines. Just from seeing that I would be cautious of these lines if the center A and B lines are cascaded instead of being continuos.
*not a rigger but seems like too much stress on the center lines when cascaded*

Hey all.

I'm writing this note because there's recently been big flaws in recent BASE canopies design, and I notice that not everyone of us seem to take it into consideration - so I will try to resume facts in a simple way. Your feedback is important and only a good synergy in our small community will ensure to positive evolution of the sport!

If you don't want to read further : Dacron 400 is NOT suitable for basejumping.
If you have such lines, send your canopy back to the manufacturer and ask for a new lineset.

---

The new trend of Lightweight Canopies

With the newest materials and technologies, there is an increasing demand from the customers to have lightweight canopies on the market. However, the structural needs inherent to the sport are still the same!

In rockclimbing and mountaineering, when it gets to gear developement, the motto is to "have the bones breaking before the gear". Equipement manufacturers and enthusiasts of such sports have been dealing with the structural problems of life-saving gear for falling human bodies for more than a century now.
Hence, using either the UIAA or the EN standards as a basis for designing basejumping gear is a good idea.

Long story short, if the gear is strong enough to withstand a pull force of 22kN, it's okay. If, for whatever reason, it goes under this limit, there's going to be accidents that could have been easily avoided. Moreover, the responsibility of the gear manufacturers and resellers in our sport will sooner or later be questioned so we really should ask ourselves about all that early enough...

Facts :

1) Dacron 400 is used for ultralight canopies lines (around 1999)
2) From what I know it's been used in some of these models : Feather - Flik Ultralite - Trango
3) Jeremy Graczyk dies on the Eiger (2011) because of multiple line failure on his canopy (the same Dacron 400)
4) Summer 2012 , I notice that :
- One manufacturer have grounded and recalled all the canopies to have this issue solved by using stronger materials.
- Another continues to sell lightweight canopies using Dacron 400 to medium weighted jumpers (85 kg)
- Another one continues to sell ligthweight canopies using Dacron 400 stating "it's okay for light jumpers"...

5) Two days ago, a french jumper informed me just after his jump that he had lines broken on his 150-jumps-old light canopy on a wingsuit jump. Guess what kind of lines..
Hopefully, there was huge flat grassy landings on this area and he managed get back to the ground without too much damage.


Conclusion? Dacron 400 sucks !



Evaluation of minimal structural needs for BASE jumping gear :

- Documented cases of 12g acceleration peaks have been measured in skydiving on "hard openings". Well, I don't know anything about skydiving but I guess that it's going to be at least as high in basejumping - or probably higher...And since more jumpers are complaining about being slammed in basejumping - I also assume it's going to happen more often as well..
- The human body can withstand a vertical negative acceleration of 18g during 0.6 seconds whithout being harmed (NASA values - ideal case not in a base harness..)
- This correspond to an applied force of ~18kN to a human body of 100kg during 0.6s (which is quite the same order of magnitude as the UIAA and EN standards for climbing equipment - around 20kN)

Note : following numbers comes from video analysis unless stated otherwise - there might be some bias - but I feel it represents in a realistic way the mechanical efforts exerced on base gear

Normal opening :
A "normal opening" (fast but not painful) in base is something like going from 45(m/s) to 5(m/s) in about 0.75s, ideally following a linear decceleration. This gives us an acceleration around (5.5+1) = 6.5g.

Extreme case :
Let's try to evaluate what is "getting slammed to the max" in BASE. The "extreme case we want to survive" is more or less like a terminal-velocity slider down opening (that has been successfully survived at least 2 times!). From my point of view, BASE gear in good state should be strong enough for that - but your mileage may vary ..

.The "high stress" phase of deceleration lasts something around 0.25s
.The jumper is going from something around 45(m/s) to 5(m/s) during that time lapse over a distance of about a line-length or 5m..
.It's painful, requires the jumper to stop (jumping) for a while, might break a few ribs and hurt in a recoverable way the spinal bones /junctions.
.The resulting acceleration is around 16g. (plus gravity -> 17g)
*I'm assuming a linear acceleration, in real life there will very likely be a peak between 20-30g for a few milliseconds

We know that the central lines are exposed to more stress than the other ones, especially the front ones. Add to that that a canopy will sometimes withstand most of the load peak on just a few lines because perfectly homogenous opening and line loading are by far not the absolute truth..

If my life depends on it, I would assume that ~ 10 lines can be potentially getting 80% of the total load whithout material failure (and that's some very personal margins!)

Other factors :
We usually change the lines when they are "visually worn out". Polyester (Dacron) is not really subject to fatigue in our case (small amount of load cycles), neither subject to UV or chemical alteration of any kind. Abrasion is the main factor, being it because of the slider or combined with the presence of small particles inside the braid.

Typically, a professionnal rigger will tell you to change the lines when they have lost 30% of their strength - this is when they are "visually getting to the end of their life". We expect the lines to be still strong enough to meet our needs at the end of their lifespan.

Then we have to add the weak point induced by line junction. Even if a state-of-the-art perfectly manufactured glued fingertrap can weaken the line by only 5% of it's tensile strength, the real case of a good quality commercial stitched fingertrap will likely reduce it by 15% at least.


So What ?

So a very quick approximation for a jumper of 100kg give us a minimal required strength of :
80% x 17(g) x 9.81(m/s2) x 100(kg) / 10(lines) = 133daN / line

Now let's try to determine what a Dacron 400 line gives ...
400lbs = 181kg or 177daN
minus 15% (junction / stitched fingertraps)
minus 30% after 2-4 years / 300 jumps for dacron (and note that some of the lines can get damaged way more than that!)

Ending in a breaking strength of..105daN


Now, let's imagine our hypothetical 100kg jumper with shoes, clothes, helmet, and a pair of sunglasses. That makes 107kg or something.
And he's hanging on a tree. By a single line that he just removed of his canopy. Just to test it.

Do you expect the line to break?

...because it will..



What should we keep in mind? ... dacron 400 will probably break before we expect it to break. Given our visual appreciation and our expected lifespan.

Dacron 575? ...154kN/line in the same scenario...that's just enough.

Spectra 725? it's even lighter than Dacron 400!
Why would you slider-down a ligthweight canopy anyway? To benefit from the improved aerodynamics of smaller packing volume?

Oh yeah, I guess the new wingsuits are flying so slow that the slider has become obsolete...

BASE canopies used to all be massively overbuilt tanks.

For the last 10 years or so, most manufacturers have been moving toward lighter and lighter canopies. I think they've mostly done this to respond to market demand.

We've seen lighter weight lines, cascaded A/B centerlines, less reinforcement and lighter fabric.

I think that we all knew at some point we'd hit the limit of what was feasible for BASE gear. There had to come a point at which the gear was lightened to the point that it was no longer suitable for day-to-day BASE jumping.

I think we've gotten to that point. It's time to back off a bit and make things a little heavier.

Is saving a few pounds on the hike really worth this?

But you have mentioned before that you have a Flik Lite in service as a student rig. Both the Flik lite and the Flick Ultralite use 400 dacron. Did you reline the Flik lite or is it suitable for slider off delays?

Also, I'd like to see how Todd and the rest of the Apex crew respond to this thread. I now jump a Flik lite and have been really happy with it. No sign of wear thus far, but I am mainly jumping it SD in the 1-4 second range (90%).

Hmmm...More info please.

would direct lines on the center cell A+B's help a bit ? it seems that these lines are the ones who take most abuse on opening.

that or stronger Dacron there ?

Definitely.

Basically, the center A+B lines are way more stressed. Either you keep the cascade and user stronger material - either you use 4 continuous lines of the same material that is used for all other lines.

This ensure a more homogeneous wear of the lineset.

Not reinforcing this part of the gear makes absolutely no sense when you try to make the best compromise between weight and strength.

Yet even with a good design, you need appropriate material.

I'll still be more confident jumping my collector-750-jump-old mojo. Okay, it's a little overbuilt and begins to open slowly ... but it's not desintegrating over my head!

Respectfully, what is your background? And what testing have you done or witnessed to prove these theories? I'm questioning because I have actual physical interest in this thread.

Started paragliding a dozen of years ago or something. Worked into mountaineering gear mechanical engineering. Discovered fibers, worked on development of ultralight webbing for climbing harnesses and various other needs. Switched to paragliding designing and manufacturing. Learned stitching, tried to understand aerodynamics, improvised myself base-rigger-hobbyist, built a base harness, went jumping of cliffs, there i am. Hooked.

What I know about lines is widely derived from past experience and what i found in the literature. I've Been doing paragliders yearly checks to learn how material is changing with age and use in real environment - mostly in terms of porosity / strength / shrinkage - we test-break a few chosen lines to evaluate the residual strength of the lineset here because visual aspect is not representative. Obviously I felt the need to try with different kind of lines as well: ) Having a stress/strain test bench available helped me to validate the best ideas found in Dan Poynters book for general stitching / fingertrapping or in general for fibers assembly.

In the particular case of the parachute center cell A/B reinforcement, it's just a general engineering concept coming from the industrial need of effort/cost optimization. You want ideally the whole stuff to get homogeneously to the end of it's lifespan, so you can throw away everyting altogether when it's worn out. Or, for a sub-set of a system, ie. a lineset, the optimal case is to change the whole lineset rather that changing the center lines each 100 jumps, then the whole set each 400 jumps.

And this is the reason why you can choose the color of the center cell and stabs of a light canopy!
The NCV PN9 light fabric is new. Any fabric type is only cost effective if you produce a minimal quantity (for nylon ripstop usually something like 5000m of one kind (weaving/coating/color)). Basically the first color produced was gray. But it's not as durable as F-111, and since the center cell is going to be more stressed, and earlier worn out - it makes sense to build it with classic fabric instead of light one.
The classic F-111 being available in any possible color even in small quantity - because the skydiving industry is ordering enough for the productions to run constantly at an predictable yearly volume - it's possible to propose to the customer to choose the color of that part of the canopy.

There's quite a bunch of articles and studies of material characteristics specific to parachutes / paragliders or synthetic fibers in general available, you can pm me if you're interested in something specific I can have a look in what i have.

Despite this anonymous post, I would like to comment on some points:

- All TRANGO canopies are offered and built with 725 spectra lines, since their introduction (2007).
- few canopies were built with Dacron lines 400, on special request, and taking the following precautions: small canopy size, lightweight jumper, and especially direct lines for central A / B (very important)
- the trango, paragliding rescue version (Sup'air Base System) is certified EN. This version has 400 Dacron lines, direct lines fo central A / B. For information, to get this certification: 255 square feet canopy, suspended mass of 120 kg, drop speed 40m / s (so almost terminal), no slider!
the Trango didn't suffer any damage, the trim was still ok, and the canopy flew perfectly after that.

These information are valid for Trango canopies only.

Sorry JeanNoel for my lack of geekitude, didnt take time to fill my profile. Im simon living in geneva, we know eachothers, neighbour!

I'm totally in line with you for the restriction of the use of weaker lines, and I am by no means accusing or judging anyone.

I just tried to present facts and a possible coherent explanation on why the lines failed whithout warning.

I made an hypothetical scenario with an imaginary jumper getting to the point where his lines are not strong enough anymore. At the same point, with the same hypothesis, a 50kg jumper will still have a security factor of 2. And it's not my goal to say if it's enough or not. Neither is my business to say if and how much the manufacturer has to charge the client asking for a lineset change, whatever the reason!

We are all responsible of our choices, however i feel that most of the people will see the lines stronger than they really are, in some specific conditions, especially with Dacron 400 after 300 jumps, when it still "looks okay".

Our referencial is based on "massively overbuilt tanks" as Tom says, meaning 800-900 lbs Dacron lines - so the apparent wear we are used to evaluate amongst the time can be misleading when we project that on newer, weaker materials.

Now saying that Dacron 400 is a poor choice and that cascaded AB central lines is a poor design is only a personal point of view based on personal needs and priorities.

If I wanted a canopy to decorate my living room, a "good design" would only be based on the color scheme! again, it's an opinion and there's no absolute truth.

Thank you for your additional information - this is the only way to solve a problematic that is concerning many jumpers.

Yet I (and probably many others) would be very interested in hearing your (personal) opinion on choosing Dacron 400 as lineset material for a light canopy, given the difference in weigth/volume compared to heavier polyester lines, and as well in comparison to Spectra and the drawback of less elasticity on openings..


best regards,
simon

*Edited to add:
The EN certification for paragliding rescues is not stating anything in case of a repeated use...

I talked to a well known, and highly regarded rigger in our area, and if I remember correctly, he stated the same thing about the cascaded AB lines being a bad idea, and there is a weak spot in the cascade line as pictured in one of the above comments. Direct A and B lines are stronger.

The feather recall replaced the inner a/b lines with continuos 600 lbs Dacron.

Simon,

I don't know if we have met, but thank you for sharing your observations, collected data, and conclusions.

I just received this service bulletin from Apex BASE, regarding 400 pound dacron cascaded A/B centerlines on Flik and FOX Lite and UltraLite canopies.

The service bulletin, has certain dates on it, has APEX changed the design post September 2011?

hey tom, can you for matter of completeness add what "Replace the center A lines in accordance with PMP-0712" exactly means?
continous 400lb center A and B lines?
500lb dacron center A and B lines?
whats apex approach to fix this?

thanks

There is a sticky thread on this going on in General...

They are offering replacement lines with 525 for the inside As, and new B cascades in 400 to make it easier to replace the lines.

From an email I received earlier today:

In reply to:Dear Customer,

You are receiving this email because you purchased (invoice date) a Lite or Ultralite model of the FLiK or FOX BASE parachute between September 2008 and September 2011.

There have been two non-fatal incidents, both occurring the weekend of June 29th, where 400lb center A lines failed just below the B line cascade. One jumper reported 80 jumps on the lines and the other reported over 100 jumps.

We will be emailing you our Product Modification Procedure (PMP-0712) as soon as it is available. If you own a canopy covered by this Service Bulletin and you would like to receive your manufacturer covered replacement center cell (#4) A and B lines, please contact us at perris@apexbase.com. In your email, please include your canopy serial number and current shipping information. Senior and Master Parachute Riggers or the foreign equivalent have been authorized to perform the modification.

We apologize for the inconvenience, appreciate your business, and look forward to serving you in the future.

Best Regards,

The Apex BASE Team

I assume that they have. Otherwise they wouldn't have an end date to the service bulletin.

I don't think they have released PMP-0712 yet.

It's my understanding that the fix is something like cascaded 600 pound center lines.



They are planning to ship new lines to all owners who they can find (so you should contact them if you own one of these canopies). They will pay the shipping to get the lines to you.

They will also perform the repair free of charge at their facility in Perris Valley, if you can get the canopy to them.

It's not clear if they will cover shipping costs to return the canopy to them (and then back to you). I think that the shipping costs to get canopies back from all over the world could be quite high.

If you own one of the canopies effected by this service bulletin, you should definitely contact Apex directly.

Is the Base with Trango? Acording to supair and from what we saw during packing.. it is a Troll 2-255 R (EN 12491 : EP 062.2012) maybe he made a typo..

What about the Dacron 400/525 mix?

Dacron 525/400 mix is just as good as 525/525.

The main problem with the 400lbs is when it's used on a low line separating in two high lines. Then you have the load of two attachment points on a single low line. If this line is 400lbs it's too weak.

Actually the mix of diameter is even better than a cascade made with only one type of line. If the inserted line is smaller, it make a smoother bump at the bottom of the fingertrap. This point is the weak point where it generally breaks, and the slider will wear out this part much more if the change of diameter is abrupt.

As long as the higher line is at least 50% of the strength of the low one, it's just as good.

But this is only a structural point of view as there might be other problems with very different diameters in terms of dimensional stability or propension to generate knots or entanglements.