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Higher reserve pull force on dirty rig (& reserve loop)?

 

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pchapman  (D 1014)

Jan 24, 2014, 10:29 AM
Post #1 of 29 (3115 views)
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Higher reserve pull force on dirty rig (& reserve loop)? Can't Post

I had a customer's rig come in that had a quite high reserve pull force when I opened it for repack, over 35 lbs. The jumper had been to Perris Valley and the rig was covered in fine grit/dust. The reserve loop was dry & gritty to the feel, like a fine sandpaper. Just opening a flap on the rig would create a little cloud of dust. (Dust of a mineral origin, not at all like household dust.)

It was a rig with a really tight loop to begin with, I think one of those "22 lbs of pull force... after leaving it overnight" deals. The loop had been well lubricated at the previous repack. (While that is normally good, if the silicone's effect is subsequently neutralized, that won't be good for pull force.)

So have riggers out there seen unusual increases in pull force, due to dirty rigs?

Just curious. Usually the rigs I pack aren't used in the desert, and when I have come across one that was, it was never as dust coated as this one rig.

(The rig got washed before the repack!)


DocPop  (C License)

Jan 24, 2014, 11:14 AM
Post #2 of 29 (3021 views)
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Re: [pchapman] Higher reserve pull force on dirty rig (& reserve loop)? [In reply to] Can't Post

It's possible that the hard pull was due to grit/dirt in the reserve rip-cord housing.

Was it a regular steel rip-cord cable?

ETA: "Well-lubricated" adds credence to my theory. More lube on the cable = more dirt stuck to it.


(This post was edited by DocPop on Jan 24, 2014, 11:15 AM)


JerryBaumchen  (D 1543)

Jan 24, 2014, 11:28 AM
Post #3 of 29 (2987 views)
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Re: [pchapman] Higher reserve pull force on dirty rig (& reserve loop)? [In reply to] Can't Post

Hi Peter,

I have also noticed this over the years. The first time in Australia back in '91 with a rig that I had built for a friend. He lived somewhat in the 'outback' where it was dry & dusty.

I have not taken any data other than the old 'calibrated arm' method.

However, if one merely gives it some thought, I do believe that your concept is valid.

This should get some discussion going; and that is a good thing.

JerryBaumchen

PS) Re: 'The loop had been well lubricated'

I have long felt that this can contribute to this situation; but I have no testing/data to verify.


Southern_Man  (C License)

Jan 24, 2014, 12:16 PM
Post #4 of 29 (2936 views)
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Re: [DocPop] Higher reserve pull force on dirty rig (& reserve loop)? [In reply to] Can't Post

DocPop wrote:
It's possible that the hard pull was due to grit/dirt in the reserve rip-cord housing.

Was it a regular steel rip-cord cable?

ETA: "Well-lubricated" adds credence to my theory. More lube on the cable = more dirt stuck to it.

I believe the lubricated in this instance refers to the reserve closing loop, not the reserve cable.


chuckakers  (D 10855)

Jan 24, 2014, 2:59 PM
Post #5 of 29 (2823 views)
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Re: [pchapman] Higher reserve pull force on dirty rig (& reserve loop)? [In reply to] Can't Post

pchapman wrote:
I had a customer's rig come in that had a quite high reserve pull force when I opened it for repack, over 35 lbs. The jumper had been to Perris Valley and the rig was covered in fine grit/dust. The reserve loop was dry & gritty to the feel, like a fine sandpaper. Just opening a flap on the rig would create a little cloud of dust. (Dust of a mineral origin, not at all like household dust.)

It was a rig with a really tight loop to begin with, I think one of those "22 lbs of pull force... after leaving it overnight" deals. The loop had been well lubricated at the previous repack. (While that is normally good, if the silicone's effect is subsequently neutralized, that won't be good for pull force.)

So have riggers out there seen unusual increases in pull force, due to dirty rigs?

Just curious. Usually the rigs I pack aren't used in the desert, and when I have come across one that was, it was never as dust coated as this one rig.

(The rig got washed before the repack!)

I have trouble believing someone would jump a rig so dirty that dust flies off of it when a pin cover is opened.


artard  (B License)

Jan 24, 2014, 3:16 PM
Post #6 of 29 (2797 views)
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Re: [chuckakers] Higher reserve pull force on dirty rig (& reserve loop)? [In reply to] Can't Post

chuckakers wrote:
I have trouble believing someone would jump a rig so dirty that dust flies off of it when a pin cover is opened.

I take it you've never jumped at burning man? Smile


Liemberg  (Student)

Jan 24, 2014, 3:26 PM
Post #7 of 29 (2784 views)
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Re: [chuckakers] Higher reserve pull force on dirty rig (& reserve loop)? [In reply to] Can't Post

Quote:
I have trouble believing someone would jump a rig so dirty that dust flies off of it when a pin cover is opened.

Truman Sparks would jump a rig like that! Smile


chuckakers  (D 10855)

Jan 24, 2014, 3:32 PM
Post #8 of 29 (2776 views)
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Re: [artard] Higher reserve pull force on dirty rig (& reserve loop)? [In reply to] Can't Post

artard wrote:
chuckakers wrote:
I have trouble believing someone would jump a rig so dirty that dust flies off of it when a pin cover is opened.

I take it you've never jumped at burning man? Smile

No I haven't. Nor have I jumped at Perris or Eloy, but if I did I would be cleaning my rig before it creates a dust cloud just from opening a flap.


chuckakers  (D 10855)

Jan 24, 2014, 3:32 PM
Post #9 of 29 (2771 views)
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Re: [Liemberg] Higher reserve pull force on dirty rig (& reserve loop)? [In reply to] Can't Post

Liemberg wrote:
Quote:
I have trouble believing someone would jump a rig so dirty that dust flies off of it when a pin cover is opened.

Truman Sparks would jump a rig like that! Smile

That scene is the first thing I thought of when I read the original post!


pchapman  (D 1014)

Jan 24, 2014, 3:48 PM
Post #10 of 29 (2739 views)
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Re: [chuckakers] Higher reserve pull force on dirty rig (& reserve loop)? [In reply to] Can't Post

chuckakers wrote:
I have trouble believing someone would jump a rig so dirty that dust flies off of it when a pin cover is opened.

Newer jumper, vacation trip to the US. Yeah, there was a dust cloud when I opened the main pin cover flap.

It wasn't like the rig was muddy or anything. It looked relatively normal, just that the mostly black rig was slightly faded.

But if you vacuumed it, you would create a distinct stripe of more intense black between two areas of 'faded' black...


@ docpop: Yes it was the loop, not the ripcord cable, that was siliconed. Still, grit in the housing might increase the pull force a little bit in any case.


johnmatrix  (D 9999)

Jan 24, 2014, 4:02 PM
Post #11 of 29 (2724 views)
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Re: [pchapman] Higher reserve pull force on dirty rig (& reserve loop)? [In reply to] Can't Post

What do you think might have caused it?
Particle build up on the loop where the pin passes through? Maybe also on the grommet where the pin touches?


pchapman  (D 1014)

Jan 24, 2014, 5:30 PM
Post #12 of 29 (2660 views)
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Re: [johnmatrix] Higher reserve pull force on dirty rig (& reserve loop)? [In reply to] Can't Post

johnmatrix wrote:
What do you think might have caused it?
Particle build up on the loop where the pin passes through? Maybe also on the grommet where the pin touches?

Admittedly I didn't research it closely. Ideally I would have made a new loop and reclosed it right away to test the difference.

Maybe it was a bit of everything, grit increasing friction where ever the pin and ripcord pressed against other structures. But it would be the loop where grit could get right into the material the most.


dpreguy  (D 835)

Jan 25, 2014, 11:49 PM
Post #13 of 29 (2330 views)
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Re: [pchapman] Higher reserve pull force on dirty rig (& reserve loop)? [In reply to] Can't Post

Opinons about dust affecting pull force are just that. Opinions. Only testing could credibly answer that question.

I'm not at all in agreement that you can blame gritty desert dust for the hard pull. If it pulls hard, (greater than 22 lbs) it is most likely that the loop was simply too short to begin with.

If someone does test the gritty dust's effect, then we will abide with those results. Until then, look for the usual cause of any hard pull = loop too short to allow a legal pull.


gowlerk  (C 3196)

Jan 26, 2014, 8:01 AM
Post #14 of 29 (2178 views)
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Re: [dpreguy] Higher reserve pull force on dirty rig (& reserve loop)? [In reply to] Can't Post

I recently had a customer bring me a Wings for a repack. I looked at it and admired the nicest, cleanest looking pack job I'd ever seen on a Wings. It was a larger one and and the cap was nicely sunk into the pack job. I was very impressed and wondering if would be able to do as well.

Until I measured the pull force needed to open it. You guessed it....35lbs. The loop was too short, but it sure looked nice. Of course this doesn't really have anything to do with dust, and I also doubt that dust had much to do with the rig in question here.

Ken


Boogers

Jan 27, 2014, 9:35 AM
Post #15 of 29 (2042 views)
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Re: [pchapman] Higher reserve pull force on dirty rig (& reserve loop)? [In reply to] Can't Post

pchapman wrote:
grit in the housing might increase the pull force a little bit in any case.

How does one clean that? Do you run a shotgun cleaning patch through it attached to the end of a flexible cable? Blow high pressure air through it? Run water through it?


(This post was edited by Boogers on Jan 27, 2014, 9:38 AM)


RedundantRigger  (D License)

Jan 27, 2014, 10:42 AM
Post #16 of 29 (1997 views)
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Re: [Boogers] Higher reserve pull force on dirty rig (& reserve loop)? [In reply to] Can't Post

I know a guy who cleans them on every repack he does.
He feeds flexible metal wire through the housing, then he bends the wire around a small piece of cloth. The cloth is then soaked in some kind of solvent. I believe a clean form of gasoline( he gets it at the pharmacy), it all evaporates away after. He then pulls the assembly back through the housings.


Premier skydiverek  (C 41769)

Jan 27, 2014, 3:11 PM
Post #17 of 29 (1887 views)
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Re: [RedundantRigger] Higher reserve pull force on dirty rig (& reserve loop)? [In reply to] Can't Post

...could it make the situation worse?:

http://www.dropzone.com/...ish%20clean;#4224289


RedundantRigger  (D License)

Jan 27, 2014, 3:51 PM
Post #18 of 29 (1858 views)
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Re: [skydiverek] Higher reserve pull force on dirty rig (& reserve loop)? [In reply to] Can't Post

That makes sence, I guess it could....

There where some bulletins concerning the subject:
http://www.dropzone.com/...ble_Housing_569.html
And also a french one, about somebody using a bad kind of oil for lubricating. Apparantly it hardend up in there or something.... But I never found it.


riggerrob  (D 14840)

Jan 27, 2014, 4:58 PM
Post #19 of 29 (1815 views)
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Re: [RedundantRigger] Higher reserve pull force on dirty rig (& reserve loop)? [In reply to] Can't Post

Parachutes de France issued that Service Bulletin because of too much "cutting oil" remaining after the housings had been formed/rolled.


riggerrob  (D 14840)

Jan 27, 2014, 5:02 PM
Post #20 of 29 (1811 views)
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Re: [dpreguy] Higher reserve pull force on dirty rig (& reserve loop)? [In reply to] Can't Post

dpreguy wrote:
Opinions about dust affecting pull force are just that. Opinions. Only testing could credibly answer that question.

I'm not at all in agreement that you can blame gritty desert dust for the hard pull. If it pulls hard, (greater than 22 lbs) it is most likely that the loop was simply too short to begin with.

If someone does test the gritty dust's effect, then we will abide with those results. Until then, look for the usual cause of any hard pull = loop too short to allow a legal pull.

..................................................................................

Back when I rigged in "dusty" Southern California, I test-pulled a bunch of cutaway cables. Many required a 25 pull to extract them. After cleaning, pull forces dropped to less than 5 pounds.


sundevil777  (D License)

Jan 27, 2014, 7:17 PM
Post #21 of 29 (1766 views)
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Re: [riggerrob] Higher reserve pull force on dirty rig (& reserve loop)? [In reply to] Can't Post

riggerrob wrote:
dpreguy wrote:
Opinions about dust affecting pull force are just that. Opinions. Only testing could credibly answer that question.

I'm not at all in agreement that you can blame gritty desert dust for the hard pull. If it pulls hard, (greater than 22 lbs) it is most likely that the loop was simply too short to begin with.

If someone does test the gritty dust's effect, then we will abide with those results. Until then, look for the usual cause of any hard pull = loop too short to allow a legal pull.

..................................................................................

Back when I rigged in "dusty" Southern California, I test-pulled a bunch of cutaway cables. Many required a 25 pull to extract them. After cleaning, pull forces dropped to less than 5 pounds.

Cleaning of the housings?


dpreguy  (D 835)

Jan 27, 2014, 7:42 PM
Post #22 of 29 (1753 views)
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Re: [riggerrob] Higher reserve pull force on dirty rig (& reserve loop)? [In reply to] Can't Post

What do cutaway cable pull problems have to do with reserve pull force?

To compare these is just guessing.


RedundantRigger  (D License)

Jan 28, 2014, 1:43 AM
Post #23 of 29 (1695 views)
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Re: [riggerrob] Higher reserve pull force on dirty rig (& reserve loop)? [In reply to] Can't Post

riggerrob wrote:
Parachutes de France issued that Service Bulletin because of too much "cutting oil" remaining after the housings had been formed/rolled.

I stand corrected! Do you have it by any chance?


leon.hill

Jan 28, 2014, 4:10 PM
Post #24 of 29 (1552 views)
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Re: [dpreguy] Higher reserve pull force on dirty rig (& reserve loop)? [In reply to] Can't Post

dpreguy wrote:
What do cutaway cable pull problems have to do with reserve pull force?

To compare these is just guessing.

Every time the cable housing changes direction (rounding over the shoulder for example), the cable inside makes contact (friction increases) and the pull force goes up.


(This post was edited by leon.hill on Jan 28, 2014, 4:13 PM)


dpreguy  (D 835)

Jan 28, 2014, 5:54 PM
Post #25 of 29 (1508 views)
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Re: [leon.hill] Higher reserve pull force on dirty rig (& reserve loop)? [In reply to] Can't Post

Yes, angles/bends increase friction, but that is off topic.

Angles and bends have nothing to do with the original post, implying that gritty dust was the cause of a hard pull on a rig with a stainless steel cable ripcord. I doubted that gritty dust was the cause. If the rig had a hard pull, it was probably packed too tight. Looking for untested causes is ignoring the obvious. Yes, friction is always increased with grit, and reduced with good lubrication, but to look to grit as the cause of the hard pull on the reserve was a stretch. (Actually there was no report of even finding grit in the housing. Just a dust 'poof' when the flap was whacked, or something like that. Just an example of guessing)

I do not doubt the pull force examples on nylon cutaway cables before and after cleaning and lubricating, but once again, not directly translatable to a stainless steel cable
situation. Lacking testing; look for the obvious cause.


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