How much does it cost to failure test something

[BlindBrick 0]

I am seriously thinking about getting a new harness for my Mirage this winter. There's nothing wrong with mine now, other than the fact that I bought a stock rig(which is what I could afford then as a college student) and would now like a fitted harness.

As a big jumper I've gotten a lot of grief from my fellow jumpers who fear that I'm pushing the harness/container past its structural limits. I've pointed out to them that I've discussed this with both the Mirage guys and Bill Booth and that this is not a real issue, but they don't listen.

I was thinking that when I have the harness changed, I could have samples from the old harness destruction tested. Won't do much for me, but if I had solid proof from a real life example to disseminate, it might make life easier for other heavy jumpers who might be getting grief.

So I was wondeirng, how much does that type of testing run?

-Blind

"If you end up in an alligator's jaws, naked, you probably did something to deserve it."

[Cloggy 1]

I guess it shouldn't be expensive at all... Engineers love destructive testing

Try to find a tech college. They might have a test rig for pull testing? Make it into a student project.

Otherwise, steel cables and slings etc. basically anything used for lifting or hoisting needs to be pull tested and certified every year or so (At least on this side of the world). So a company doing that kind of work should have a test rig. Maybe if you walk in there on a friday a'noon with a case of beer??
Note that static testing might not be equivalent to the dynamic loading that you subject the rig to during parachute opening. And proper clamping of the webbing could be a challenge too.

[pilotdave 0]

RWS tests a sample of every roll of webbing they buy. I dunno if Mirage does the same, but I'd assume they do. RWS was happy to demonstrate their destruct-o-webbing (tensile test) machine when I went for a tour. Took a few seconds to set up and a couple minutes to run the test. I'm not sure what good it would do for ya, but I bet mirage could run the test for you easily.

Dave

[JerryBaumchen 1,048]

Contact Bill Coe at Performance Designs. He & I have been talking and emailing about this very thing on the harnesses that I build.
Apparently, they do it somewhat 'routine' and have all of the equipment to do it.

[BlindBrick 0]

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I'm not sure what good it would do for ya, but I bet mirage could run the test for you easily.

Won't do a whole lot for me. This is more for other heavy jumpers who incorrectly have lighter jumpers telling them that they are pushing their gear to the failure point. Gear fear sucks, and needless gear fear sucks even more. I'm just trying to prevent that for some future heavy jumpers by obtaining data that even if it will not silence the critics will reaasure the heavier jumpers.

-Blind

-blind

"If you end up in an alligator's jaws, naked, you probably did something to deserve it."

[LawnDart21 0]

Do manufacturers like Mirage or RS currently have a maximum suspended weight for their harnesses?

I can imagine a scenario with a sport rig with B-12s on the leg straps. Lets say the manufacturer says "400 lbs max load" on a harness. That would mean each leg strap webbing is capable/rated to safely handle 200 lb loads each. Now lets say we have a 300 lb jumper jumping a container with B-12s, that is appropriately under the 400 lb limit. If a B-12 comes undone in freefall and the jumper deploys, there is now a force of 300lbs being bore by one remaining leg strap/webbing. Could that scenario cause an otherwise "under the weight limit jumper" harness failure at the other leg strap?

--
My other ride is a RESERVE.

[mjosparky 3]

I have never seen or even heard of a B-12 coming undone in free fall. Do you have any first hand knowledge of this happening? They have the same rating as the friction adapters used in a step in and they were designed for leg straps.

Sparky

My idea of a fair fight is clubbing baby seals

[Mostly_Harmless 0]

There has to be some sort of safety factor involved when designing stuff. As an engineering student I would believe that the max rated weight is still under what the actually rig can withstand. A test would be interesting, let us know how it goes.

_________________________________________
www.myspace.com/termvelocity

[BIGUN 1,053]

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This is more for other heavy jumpers who incorrectly have lighter jumpers telling them that they are pushing their gear to the failure point.

Tell the lighter guys to hush?

Nobody has time to listen; because they're desperately chasing the need of being heard.

[pilotdave 0]

But without knowing how much force you put on your harness during a hard opening, I don't know what you'd do with any numbers you're given for the strength of your harness. If you get it tested and it breaks at 2000 lbs, how will you know if that's good or bad? What parts would you have tested? Just a section of main lift web or would you include some hardware/stitching?

Dave

[BlindBrick 0]

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I have never seen or even heard of a B-12 coming undone in free fall. Do you have any first hand knowledge of this happening?

About a year ago we had a bit of a discussion in the forum about why I felt quick release hardware on legstraps was not safe for sport jumping. In that thread I mentioned the fact that a B12 was accidently released in FF at my DZ. That was a case where on a hybrid, the low guy took an inside grip on a legstrap. When he did, he accidently opened the other jumper's b12 and caused the strap to release when he floated on the formation.

-Blind

"If you end up in an alligator's jaws, naked, you probably did something to deserve it."

[JerryBaumchen 1,048]

Hi there Mostly Harmless,

First, welcome to the world of engineering; I are one.

I think (and I'm too lazy to get up and go look) that the current TSO standard requires that a component be tested at 1.2 times the placarded speed & at 1.2 times the placarded weight.

That would be a safety factor of 20%; right?

[mjosparky 3]

You got it.

SAE AS8015 Revision B

4.3.4 (Continued):
a. Test weight = Maximum operating weight limit x 1.2
b. Test speed = Maximim operating speed limit x 1.2

Sparky

My idea of a fair fight is clubbing baby seals

[MikeForsythe 0]

Their concern as far as the harness/container is probably unfounded. I pulled some test that were done a while back and sport rigs were failing at around 8,000lbs and tandems at 14,000lbs. Reserves canopies are running around 3,500lbs. The week link is usually the main risers and that is what you want to fail if something has to.

Now lets put the above into perspective. Say that you are 275lbs., that would mean you would have to pull around 30G’s symmetrically to get to harness failure. At that point you are soup.

As to the B-12s, they are different than quick releases. B-12s are rated at 2,500lbs. which would give you a 5,000lb. symmetrical failure. They are not a problem and are on about every military rig. There is also a big difference between rated and failure limits. I don’t know of a system out there that fails at 1.2 times the rated capacity.

And David is right. We test every lot of material to destruction. That way we not only know if it passed the rated test but what it will go to. And when we test systems, we put load cells on so that we can say that it was an 9.5G opening and not that technical term “that it knocked the crap out of me!”

But in the end I will say that you should not exceed the rated limits. There are enough manufactures out that can make a rated TSO system for your weight.

Edited thanks to JB

Time and pressure will always show you who a person really is!

[BlindBrick 0]

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Their concern as far as the harness/container is probably unfounded.


I know this because I've talked with Bill Booth and Mirage a bit about it and I have a lot of experience with deploying at what people consider freefly speeds. It's convincing everyone else that I've had trouble with. I've really got hasseled about this to the point of temporary groundings and special jumpsuit requirements.

I am hoping that if my old harness fails at the levels the theory says. It will finally be enough to silence those critics who didn't buy the theory. And maybe that can help some heavy jumper form having to jump through the hoops I've had to.

-Blind

"If you end up in an alligator's jaws, naked, you probably did something to deserve it."

• Quote

[70sdiver 0]

what do you weight.im 295 out the door should qualify as an avil eh lol.

[JerryBaumchen 1,048]

Hi Mike,

I think you might be in error. The B-12 snap (MS22044), the B-4 snap (48B7884), and the quick ejector snap (MS22017) are all rated at 2,500 lbs. They were all used on the leg straps/leg junction of military harnesses; and some sport rigs.

You may be thinking of a military-type chest pack snap (MS22042 and/or MS70119) which are rated at 5,000 lbs. These were to attach a chest pack to a military-type D-Ring which is also rated at 5,000 lbs.

These were rated & used at the 5,000 lb value because if one side of the chest pack were to become unsnapped, the assembly could still take the full design load (anyway, that's how it was explained to me back in the 60's).

Also, in the late 60's when the MiniSystem & the StyleMaster rigs came on the market with B4 & B-12 snaps for attaching the chest reserve to the harness, some folks asked for and got their chest reserves with the 5,000 lb snaps. Being cautious, I suppose.

Now, if I am wrong on this I will gladly stand corrected.

Of course, you are absolutely correct on everything else. I cannot imagine enduring an opening shock that would cause a catastrophic harness failure. I was talking with Bill Coe about this recently and he says that his testing leads him to the same 8,000 lb number for most modern sport harnesses.

[MikeForsythe 0]

Yes, you are correct. I was sitting here looking at a tandem butterfly snap while I was typing. It failed at 5,460lbs.

Time and pressure will always show you who a person really is!

[BlindBrick 0]

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what do you weight.im 295 out the door should qualify as an avil eh lol.

Used to be about 330 OTD. Nowadays it's a little closer to 310.

-Blind

"If you end up in an alligator's jaws, naked, you probably did something to deserve it."

[riggermick 6]

I am hoping that if my old harness fails at the levels the theory says. It will finally be enough to silence those critics who didn't buy the theory.



Why do you care? Trying to educate the people who wan't to educated, who love to subscribe to their own theories of how things are is nearly always futile. Let it go! Trust the science and the engineering, it's worked for decades and no amount "classic skydiver ignorance/know it all" will change these facts.
Tell them to pick up Poynters and read it, you never know they may actually learn something!

Mick.

[masterrig 1]

Quote

I am seriously thinking about getting a new harness for my Mirage this winter. There's nothing wrong with mine now, other than the fact that I bought a stock rig(which is what I could afford then as a college student) and would now like a fitted harness.

As a big jumper I've gotten a lot of grief from my fellow jumpers who fear that I'm pushing the harness/container past its structural limits. I've pointed out to them that I've discussed this with both the Mirage guys and Bill Booth and that this is not a real issue, but they don't listen.

I was thinking that when I have the harness changed, I could have samples from the old harness destruction tested. Won't do much for me, but if I had solid proof from a real life example to disseminate, it might make life easier for other heavy jumpers who might be getting grief.

So I was wondeirng, how much does that type of testing run?

-Blind

______________________________________

Years ago, a harness that I had sent to SSK, to replace the leg-straps, was forwarded to RWS. The leg-straps had been (previously) repaired by a local Master Rigger, who used 'FF' thread! I was never charged for the 'destructive test'.
I would say, contact RWS.


Chuck

[Mostly_Harmless 0]

I believe you are right Jerry. I would tend to think that in such a risky sport the SF would be slightly higher then 20%.

_________________________________________
www.myspace.com/termvelocity