Riser Breaking Strength

[p3h 0]

Type17 is 2500# rated and Type8 is 4000# and let say they will definitely break with more load than that. Does their breaking strength refers to the each tape or both together?

So assuming the load will be distributed 50/50 to each tape, can I theoretically suspend 5000# on the Type17 and 8000# on the Type8?

[theonlyski 8]

Quote

Type17 is 2500# rated and Type8 is 4000# and let say they will definitely break with more load than that. Does their breaking strength refers to the each tape or both together?

So assuming the load will be distributed 50/50 to each tape, can I theoretically suspend 5000# on the Type17 and 8000# on the Type8?

The rated strengths for the webbing are per single length.

What are you trying to do?

"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

[Anvilbrother 0]

That weight rating assumes no compromises of the material, and will always fail at the weakest point. Grommet holes, excessive stitching, heat, uv, being bent or folded around an object, contaminants all play a part into how and where it will fail.

There are people here that have been involved in extensive gear testing and will chime in for sure. I would be interested to know if new and used risers tend to break at the same points historically.

Postes r made from an iPad or iPhone. Spelling and gramhair mistakes guaranteed move along,

[mark 107]

Quote

The rated strengths for the webbing are per single length.

Additionally, that's before you install a grommet.

Also, webbings (and tapes and lines) stretch under load. Depending on your application that may not matter. Or it may matter a lot.

Mark

[JohnSherman 1]

You might find some useful information here:
http://www.jumpshack.com/default.asp?CategoryID=TECH&PageID=RISERANALYSIS&SortBy=DATE_D
There are additional papers about risers and 3 rings at the same location

[NovaTTT 2]

Wilcox Webbing Strength Tests

"Even in a world where perfection is unattainable, there's still a difference between excellence and mediocrity." Gary73

[riggerrob 643]

Assuming that the load is evenly distributed?
Hah!
Hah!
Hah!
LMAO!
Opening shock is rarely evenly distributed left-to-right, much less fore-and-aft.

First, most people open right shoulder low, because they have not reurned to "shoulders level" after tossing their pilot-chutes.

Secondly, rear risers usually absorb more of the opening shock ... because of the brakes, etc.

[riggerrob 643]

If you are using this forum to justify over-loading sport risers ... forget about it!

You would be far wiser to buy a pair of tandem risers made of Type 7 webbing (5,500 to 6,000 pound minimum breaking strength).

Keep in mind that tandem risers raise a few compatibility questions.
Does your rig have RW-10 harness rings?
Are your cutaway housings long enough?
Are your cutaway cables low enough?
Will your riser covers still conceal the additional bulk?

All the above questions are best answered by a tandem manufacturer (Jump Shack, Parachutes de France, Strong Enterprises, United Parachute Technologies, etc.) or a Master Rigger who has a lot of experience with repairing tandems.

[JerryBaumchen 1,363]

Hi Rob,

Quote

Opening shock is rarely evenly distributed left-to-right, much less fore-and-aft.

I would probably make that 'is never evenly distibuted.'

It has been many years ago but I seem to remember some info from some testing that Para-Flite did that the center two front lines take the largest portion of the opening shock.

The webbings, tapes, etc have strength ratings. In their raw form they will 'almost' always be stronger than the rated strengths. But then we start cutting, punching holes, adding 'whatevers' and everything changes.

I would be curious as to the reasoning for the original question as that might help some of us to offer some better information.

JerryBaumchen

PS) On 21 Apr 10 I tested three samples of Type 8 webbing that was sewn with a 3-point stitch pattern, sewn with #5 cord, that was 50 mm ( ~ 2" ) long. These were tested in a calibrated testing machine and the results were:

#1 - failed at 6,720 lbs
#2 - failed at 5,780 lbs
#3 - failed at 6,300 lbs

[billvon 2,991]

>Type17 is 2500# rated and Type8 is 4000# and let say they will definitely break with
>more load than that. Does their breaking strength refers to the each tape or both
>together?

It refers to the webbing itself, not both together.

>So assuming the load will be distributed 50/50 to each tape, can I theoretically
>suspend 5000# on the Type17 and 8000# on the Type8?

IF you doubled them up and had an arrangement to evenly distribute the loads without puncturing or redirecting their loads, then yes.

However, once you start sewing them together and then have loads that pull in different directions all bets are off. Also if you're using a riser you are going to have more points of failure than just the raw material - the material near the grommet hole, the stitching right at the confluence, the 3-ring system, the edges of the links etc etc.

[p3h 0]

For those who asked why I'm asking about the riser strength - I just want to better understand and calculate which riser configuration would be more appropriate for any particular use - RW1 / RW7 rings in a standard riser configuration or RW1 / RW7 rings in a reversed riser with no grommet hole.

There is lots of interesting info about this topic elsewhere and the conclusion I got are very interesting also. For example that the difference in the leverage between RW1 and RW7 rings is so huge, than especially for heavier jumpers it really can make a difference either in hard cutaway pull during high G forces experienced or a hard opening where the yellow cutaway cable would be pulled through the riser grommet.

For example 200# guy experiencing 10G hard opening (and probably it could be even harder) receiving 90% of this force on one riser could get his yellow cable pulled through the grommet with RW7 mini rings. For skydiving it's not that of a big problem, but let say for base jumping it would be huge.

So in the end especially with the RW7 mini rings the most common failure mode would be not a riser break as I would assume before, but rather yellow cable pull due to more than 60# force transferred to the yellow cable.

[Hellis 0]

The yellow cable takes very little load of the risers.
You can try it next time you are under canopy, just try to move the loop the cable is going trough.
You will notice there is very little tension on it.

And normally in BASE you have the "french" style risers, with no grommet.
Generally people don't like them in skydiving because they can hang up while cutting away, but in BASE you generally don't cut away while still in the air.

[Beatnik 2]

Quote

The yellow cable takes very little load of the risers.
You can try it next time you are under canopy, just try to move the loop the cable is going trough.
You will notice there is very little tension on it.

During the parachute descent there is not much load on it. But P3H mentioned during opening where there can be a load put on it depending on how high the forces are, There have been cases of the cutaway cable being pulled through the grommet or kinked, which would later result in a hard cutaway.

Quote

And normally in BASE you have the "french" style risers, with no grommet.
Generally people don't like them in skydiving because they can hang up while cutting away, but in BASE you generally don't cut away while still in the air.

With reverse risers you should have a rig designed to use them. That is why they can hang up. Typically your main rings in your cutaway system should be around your collar bone. WIth reverse risers they are a little higher because the rings flip towards you when releasing. Putting them on a standard harness can result in hangups. The main reason that reverse risers aren't seen as much is because there is no standards for them. Everyone makes them slightly different. Where there are a set of construction standards for standard risers.

Additionally to my understanding why they are used in BASE is because of the large amount of container dragging during packing. Having reverse risers for a system that is traditionally not cutaway unless you are on the ground protects the locking loop from damage. That was what was explained to me.

[skydiverek 63]

Bill Booth on reverse risers:

"Reversed risers are 3 ring risers where the riser rings face the jumpers body, instead of facing away as they do on normal risers.

In a misguided attempt to make type 17 (mini) 3 ring risers stronger, the French eliminated the grommet that passes through the riser, thinking this was a weak point. They then put the "0" grommet for the closing loop to go through on a floppy 1" tab. Then, so that the 3-ring housings wouldn't have to come around to the front, flipped the riser over so that the riser rings faced the jumper's shoulders

There are three problems with this approach. 1. Risers don't break at the grommet. They break where they go around the harness ring. 2. The closing loop on reversed risers does not make the 180 degree direction change it does on properly built risers, so the release force is doubled, and the "suck through" or "jamming" force is cut in half. 3. For a 3 rings to release, they must flip through each other. Since a bag lock might not stand you up enough to pull the risers away from your body, reversed risers might not release in that situation, because your body blocks the flip through motion.

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I don't know about you, but I want my 3-rings to work EVERY time, in ANY malfunction situation. "Most of the time" just doesn't cut it. Reversed risers, soft housings, and all other "improvements" to the 3-ring lower reliability. Emergency systems are simply no place to cut corners. I cry every time I see a poorly made 3-ring, but there is nothing I can do about it, but tell you again, "There is one best way to make a 3-ring release system, and it doesn't cost a dime more to do it right. The plans are available from the Relative Workshop." How much is your life worth?

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On reversed (Integrity) risers...The scariest stories I've heard about them happen in two canopy out situations. Often, the main risers are held back across the shoulders, preventing the unfortunate jumper from cutting the main away in a "personal downplane" situation.

Reversed risers offer no advantages, have lower mechanical advantage, have no published construction or inspection specifications (so you can't tell if they are going to work in a high "G" situation), and can kill you in the above situation (and others). They should be replaced, and you should get very mad at anyone who sold them to you. The same is true for most "soft housing" 3-ring release systems."

[JohnSherman 1]

For what it is worth I will add my $0.02.
Reversed risers and risers without the traditional grommet arrangement are exactly what Bill said they are. Dangerous. I feel so strongly that about it that I think they should be band from the sport. If I ran a DZ and someone showed up with that kind of set up I would not allow it to be used.
The tab grommet looses half of it's mechanical advantage and on mini rings that makes it 15 to 1. Therefore if you weigh 150 pounds it will have a 10 pound loop load. Anything over 10 pounds loop load gets very difficult to pull if not impossible.
The "Suck through" goes from 60 pounds to 30 pounds. Easy to get on a hard opening.

Now for those of you who would disagree I suggest to you that the 2 men who have tested the 3 ring the most are both saying the same thing. Dump those type of risers for the traditional ones.

John Sherman

[riggerrob 643]

"

Quote

For those who asked why I'm asking about the riser strength - I just want to better understand and calculate which riser configuration would be more appropriate for any particular use - RW1 ... or RW7 rings ...

"

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Why are we even discussing RW-7 mini-rings? Those skinny rings have been out of production for more than a decade now! RW-7 rings fell out of fashion some time during the early 1990s!
Heck!
My Talon 2 was sewn in 1996 with the thicker RW-8 mini-rings. Parachutes de France only ever built mini harness rings with a "thick" cross-section similar to RW-8 rings.
The advantage of RW-8 rings is that their cross-section matches that of standard RW-0, RW-1 and RW-10 harness rings. That thicker cross-section vastly reduces the risk of the harness ring cutting through the bottom of the riser.