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fcajump

Reserve Pull Force - testing

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First - check this, then come back for discussion, Q/A: 

 

(Thanks to Mr. Thompson for his video, if you're here please speak up as I think you've raised a GREAT point)
I've long been an advocate with my customers that they should all have a first hand knowledge of how it feels to pull their ripcord.  Can't tell you how many (especially pilots) tell me they had never pulled one.

And when they don't pull it, I always put a scale on it and test.  (and I've found some that table-locked, nothing I've packed, but always makes me nervous).  But that only tells me how it was after the fact.  To test before it goes out, I usually use this http://www.paragear.com/skydiving/10000161/M5995/PARACHUTE-RESERVE-RIPCORD-PIN-PULL-CHECK-TOOL.  But it doesn't work on all rigs and it doesn't allow full deployment of the pin, only to move it.  (it is still MUCH better than nothing)

I'll be trying his technique (in video) on the next rig I do... I think I'll like it better.
Any manufacturer wish to comment on his discussion on pin harness/coatings?
 
At a minimum, his video should get riggers and jumpers alike thinking about this issue.

Finally, I know that in a loft is different than in the air, but it really bothers me how many in the video hesitated, looked around and waited instead of using a two-hands and powering through their pull. 

Just my $.02,
JW

PS - I'd like to know more about his fishing-line tool (4:18) and the small temp pin (4:49)... it looks like a vector pin, but smaller.. I'm sure someone knows, but I'm not placing it...

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Can a r/c pin be "field polished" to remove scratches?   (If so, how is this done?)  If it can be; *SHOULD it be polished?  ….Mfg comment on this polishing question?  *Do mfg encourage or approve of polishing a r/c pin in the field - by riggers?

 

Another topic: Question in my mind about this rigger's desire to harden pins with titanium product.  Hardening the r/c pin is only half of the friction issue.  The grommet is the other surface.  Should the grommet be similarly coated with the titanium hardening product?  Can it be?  (grommet has to be somewhat ductile/bendable to be set)  Or, am I just silly asking about hardening the grommet)

Next question in my mind about the titanium suggestion.  Can our present ripcord pins even be treated with the titanium hardening product?  ( melting point issue - alloy issue etc)  Or would the industry have to invent a whole new ripcord pin?

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I think it used to be described as “punch” instead of pull, and the distinction of urgency. A hard pull doesn’t feel so hard if you’re punching it out, and take advantage of the slack in the system to get some speed going before the real force has to be applied. It would be great to encourage specifically in training/safety day. 

Large ring risers/old school rocks.

Gotta punch it.

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Great video!

I always encourage sport jumpers to pull their own reserve ripcords when they drop off rigs for maintenance. I also invite junior jumpers to pull reserve ripcords when school rigs are due for maintenance. Many are surprised at how little effort it takes to pull a ripcord. I like to turn it into a miniature review of malfunction procedures and I deliberately stand outside their field of vision.

Ripcord pins can be polished, but only by a rigger, only with fine emery cloth and only after they are scratched.

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I just look at the video and honestly most of  the people pulling really were lame half hearted pulls.   They did eventually pull.   Most were pulling at 90 degrees to housing increasing pull force.   Notice the big gap between cutting away and pulling the reserve and stopping when it got a little tough.     Eventually using a bit of effort and pulling it.     In my opinion the issue was the jumpers effort rather than the equipment.   Pull it like you life depends upon it.     Im sure scratches are an issue but i don't believe it to be the prime factor.    I pull hundreds of reserves a year and don't experience hard pulls but i am pulling in the right direction.   

Correct training and emergency procedure execution are a bigger issue.   Ive seen similar occurrences when people pull their reserves.   Pulling once every 6 months  does little to address the issue.   I have no problem with people pulling their reserves.  

I dont doubt some containers are too tight as ive seen bent stuffeners and watched rigger struggle to close even using a torque device.   Sometimes it is technique and other times its realizing when the closure loop is too short.

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A nice selection of half-arsed pulls there. I see a lot of people who need to work on their EPs. Funny how they can actually do it when they try. smh. As for the pin issue he makes a good point but I don't think it's as big a deal as he's making out.

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(edited)

FWIW - used his technique for pull force test without full deployment this last weekend.  Worked consistently and will be my standard going forward.

For those unsure how he was setting it up, here is what I did and my results (packed Jav-Ody in for AIR, customer not present):

   - removed seal
   - routed a pull-up cord into reserve loop (as though it was just packed and pinned), leave it off to the side of the reserve pin (no tension on the cord, as though you were about to remove it)
   - place long temp pin (I used a cypres pin) _between_ the two sides of the pullup cord, sitting right next to the closing loop, parallel to the reserve pin.
   - tie the two lines of the pullup cord into a slip knot (see https://www.animatedknots.com/slip-knot)
and cinch it down as close to the temp pin as possible, trapping the temp pin next to the closing loop.
   - attach you scale to the ripcord handle (removed from pocket)
   - test by pulling the scale handle.  (make sure the shoulder of the rig is either worn by someone, or that you use something like your foot in the rig's shoulder to keep the housing as close to its normal arch as possible.

The ripcord will (should) pull clear of the housing.

Assuming you are using a scale that shows peak load, you now know what the pull force was.

If you setup the system correctly, you should now find that the rig is held closed on the pullup cord and temp pin.  NOTE: unlike when you are packing the rig, the temp pin is NOT holding the container closed on the closing loop, but on the knot in your pullup cord.  If you release the slip knot before getting the knee board back in place, you will get to a pilot-chute in the face.

Replace the ripcord, repin and seal (assuming your peak force was under 22 lbs.)  If it was high, correct your problem and reclose/retest.

On the rig I was planning to repack, I tested three times.  Twice using the above method and once without the locking system.  The pull force reported was within 1/4 lb each time.  

It would also be easy to use this technique to give your customer multiple "live fire" exercises, with minimal reset time.

Its even simpler if you are testing a rig you just closed... if you remember to test before removing the pullup cord.  Takes a minute, gives you the reassurance that its deployable and might save a life.

JW

Edited by fcajump

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PS - If anyone knows how to make (or where to get) the fishing loop he used to pull the pullup cord back through the closing loop, please drop a line.  I used a pair for small forceps, but its NOT as easy a his tool.

 

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Interesting video & discussion. From a materials point of view, I'm not sure that polishing a scratched reserve pin is a good solution, since the material is soft enough that it was able to get scratched in the first place. Polishing it up removes the scratches, but does not remove the ability to be scratched again.

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7 hours ago, IJskonijn said:

Interesting video & discussion. From a materials point of view, I'm not sure that polishing a scratched reserve pin is a good solution, since the material is soft enough that it was able to get scratched in the first place. Polishing it up removes the scratches, but does not remove the ability to be scratched again.

Agreed, but it is the mfg supplied part, and removing the scratches (if problematic) is better than not.

I'd not advocate trying to apply any after market hardening.  We've had problems in the past with metal components being processed/treated in ways that turned out to be bad in the end.

I personally saw that part of his video as an appeal to the rig/pin mfgs to consider R,D&T into having a harder layer.  If you are qualified and have the resources to do that R,D&T for the industry, GREAT... just don't experiment on customer rigs.

JW

 

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Agreed, metal hardening is a fairly involved process that requires the full skill, test facilities and QA capabilities of a manufacturer. But TiN treatment is not new, and there are plenty of companies that are skilled enough to do it. It might cost a bit more, but I see no major technical reason why a rig manufacturer cannot buy a batch of TiN hardened reserve pins (likely a pin is defined as a part number with associated drawing and material specifications) and test those for use in their reserve ripcords.

As for the grommet, unless I understand the mechanism wrong, a scratched grommet won't cause as much pull force increase as a scratched pin. The scratches in a pin hook into the loop material, meaning you have to physically either pull them out or pull apart the hooked fibres of the loop material. Scratches in the grommet are also obviously not good, since they can cause wear on the loop and/or grab the loop during the opening sequence and delay (or worse) the opening of the reserve container.

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I watched the video and its well put together and has some good merits, on another side of this topic, I recently watched a rigger apply cypress silicon to the reserve cable, I don't do that, I do put a small amount on the pin before I put it in the loop. Does anybody else put it on the cable, i'm asking because I don't see too many benefits to it

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On 1/6/2020 at 12:14 PM, fcajump said:

If anyone knows how to make (or where to get) the fishing loop he used to pull the pullup cord back through the closing loop, please drop a line

it looks like it's just a bit of fine piano wire. But there are dental floss threaders that would probably work (I think the brand is 'dentek.' They're blue, shaped like a teardrop with a long tail, and come in a pack of maybe 40-50).

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2 hours ago, airnutt said:

Does anybody else put it on the cable, i'm asking because I don't see too many benefits to it

I know a guy who used to do that (he doesn't rig anymore). To me, it seems it would only attract more grime. I'll stick with silicone spray.

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23 hours ago, airnutt said:

I watched the video and its well put together and has some good merits, on another side of this topic, I recently watched a rigger apply cypress silicon to the reserve cable, I don't do that, I do put a small amount on the pin before I put it in the loop. Does anybody else put it on the cable, i'm asking because I don't see too many benefits to it

First -sorry for the footnotes here... I can't help but include many lessons learned for the young rigger out there... so they avoid stupid/honest mistakes I've done, seen or heard...

I do a few things, none of which seem to cause issues (first priority) and seem to help (secondary consideration):
    First - when I clean*/lube* the cutaway cables, I then use the same cleaning/lube cloths on the reserve ripcord.  Just as with the cutaway cables, the lube should be _thin_ coat... don't soak it.
   Second - I use the Cypres lube on the loop IACW the mfg instructions.
   Third - I run the center of my pullup cord* (cypres loop material) through the Cypres lube cloth (to help not remove the lube from the loop as its drawn through, reduces cord-on-loop friction)

I do NOT use the Cypres lube or WD50 on the ripcord or cutaway cables as I believe they are too thick and too likely to attract dust.

Just my $.02
JW

 

*Lessons Learned/Heard/Observed:
   -  per Booth's recommendation I clean with Ronsonol* Lighter Fluid and lube with Ace Hardware Brand Silicon Spray Lube*
   -  Ransonol brand sells both Lighter Fluid and Multi-Fill Butane Fuel, both useful to those refilling the two (different) types of lighters, but to those of us who rarely use, must let refill lighters... they are different things.  You want the yellow squirt bottle.
  - Silicon Spray Lube is in a can that looks remarkably like the Silicon Spray Adhesive.  It is highly recommended that you make sure you know the difference before using... (this told me by a rigger of the highest level who made that very mistake)
  - Cleaning, and lubing with these items is simple, but can be f-ed up I'm sure...  spray some lighter fluid on a clean cloth (paper-towl) and then run the cable through it.  Repeat in a different wet part of the towel until you're no longer leading dark streaks on the cloth.  Spray a second cloth with the Lube and draw the cable though it once to apply a _thin_ coating along its length.
   - If you use the Cypres loop material for your pullup cord, finger-trap ~6" additional loop material into the middle of your pullup cord (completely encased, so the middle section is thicker with no ends sticking out).  It helps open the loop a bit to get the (temp)pin into the loop.  SSK indicated that this is approved (per Cliff at the time).  I do recommend shifting toward one end when moving it through the cutter, so that you're not trying to pull the full doubled u-turn through the cutter.
   - If you find that you are staining ANY part of the rig (flaps, risers, harness, D-bag, canopy) with the lube, STOP!!! You are using WAY TO MUCH!!!  Get help from someone who can show you how to do this right.


 

 

 

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All good points dear fcajump,

May I add that clean cables are more important than lubricated cables when jumping in the desert? Too much lu do any traps grit on the cable, increasing pull force.

That grey-black is oxidation see stainless steel from inside ths spiral-wound housing.

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Jim, I  think he's just using a curved thin piano wire similar to a wire finger trap tool. The temp pin looks like one of the welded wire main pins we used before the stainless pins came out. They were welded so the pin came off the ring as a tangent rather than a radius. (like a vector pin 9 shaped except welded wire) In my opinion a much better geometry that eliminates the leveraged pull a stainless pin can have similar to a straight pin on a throwout.  I may have to dig out some to use as temp pins.  Too lazy to go find one now for a photo.

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On 1/22/2020 at 2:52 AM, councilman24 said:

 

I used a Cypres temp pin to catch/lock the deployment and it seemed to work fine for me.

I'll look for some fine piano wire, but meanwhile the suggestion betzilla made to use dental floss threaders looks like it will work well to thread the pullup cord back in when/as necessary. 

JW

 

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Great video indeed.

If someone can help me to solve an additional mystery.

After packing, i measure the peak force and formalize it into a packing report. At next pack, usually 12 months in Switzerland, I do the same, but the peak force sometimes increases by up to 10 to 20%.( i thought about humidity and started to log it as well to see any relation, but not enough data yet).

any ideas?

jerome

 

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2 hours ago, jeanneretjerome said:

the peak force sometimes increases by up to 10 to 20%

Hi Jerome,

I know nothing about the laws in Switzerland regarding parachutes.

IMO, here in the USA, when I return the parachute to the owner after having packed it, worked on it, etc, I am no longer responsible for it.  I cannot control what the owner or anyone else would do with the parachute once it leaves my hands.  It would be airworthy & ready for usage when I return it to the owner.

Just my $0.02 in this,

Jerry Baumchen

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On 1/24/2020 at 4:03 PM, JerryBaumchen said:

when I return the parachute to the owner after having packed it, worked on it, etc, I am no longer responsible for it.  I cannot control what the owner or anyone else would do with the parachute once it leaves my hands.  It would be airworthy & ready for usage when I return it to the owner.

Jerry - From a US legal point of view, I completely agree, most especially when dealing with Racers/Reflex and Softie/Butler/Strong Longs, but changes after its left my hands can be made on most any rig.  And inadvertent contamination/mishandling certainly can.   
However, from a rigging/learning/best-practice point of view, I'm always looking for the before/after and the why.  

jeanneretjerome - I find your numbers very interesting and contrary to my experience... most the time I find lower numbers upon return (180 day cycle, but many pilot rigs only return each spring).  I attribute lower numbers due to canopy settling/compression and stretching of the closing loop(s) during wearing.  The only situation I can immediately think of that would counter that (assuming your not dealing with a field adjustable system like Racer/Reflex would be if you were using the vacuum packing method*, in which there might be some expansion after the pack job is complete...  Would be interested in seeing more of your before/after/conditions/system-type data and what you conclude...

*not a technique I use or endorse, simply have heard of:  When packed 99% (final temp pin in place, prior to ripcord) place entire rig in an appropriately sized vacuum storage bag and suck all the air out, let stand, then open vacuum bag and place ripcord.  Note: There are warnings from the AAD mfg's about using this technique.  Consult the appropriate mfg and others experienced in this method before attempting.  My thought is, if you need this you may be working with too large a reserve for the container.

I'll See your $.02 and Raise you $.01 ;-)

JW

 

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