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guy_andrews1952

How tight should my closing loop be?

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I have been jumping a J4 for about 3 years. Sometimes my rigger adjusts the length of my closing loop for me. Last week I used a packer for the first time in about six months and he changed my closing loop when I was in a class. The replacement has more play in it than the last one did. What is the proper tension?

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My rule of thumb is that if I don't have to use some effort to get it closed, it's too loose. Not talking gargantuan megamucles-use-all-my-weight-and-power thing. Just if you effortlessly can close it, it's generally an indication of the loop being too long.

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I have been jumping a J4 for about 3 years. Sometimes my rigger adjusts the length of my closing loop for me. Last week I used a packer for the first time in about six months and he changed my closing loop when I was in a class. The replacement has more play in it than the last one did. What is the proper tension?




Tight enough so that it takes some effort to close it, not too much effort though. It's a rule of thumb thing.


Mick.

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>Last week I used a packer for the first time in about six months and
>he changed my closing loop when I was in a class. The replacement
>has more play in it than the last one did.

Packers do this because it is easier for them to pack the rig that way. I've seen some horrendously loose closing loops from packers.

>What is the proper tension?

One good rule of thumb I heard was "tight enough so your girlfriend can't close your rig." Which is sexist but does get the point across that tighter is generally better. It is very hard to make a closing loop too tight; if you can close it by hand and there is any play at all, it will generally work fine as long as there are no other problems (like burrs on the closing pin.) If you make it too loose you can see out-of-sequence deployments if your rig gets hit in the door or in freefall.

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From the Aerodyne Icon manual:

“The maximum force exerted by the
bridle on the curved pin must not be more
then 6 daN. For Safety the minimum force
exerted must not be less then 4 daN."

1 daN = 1 deca Newton which is about 1kg

You can use a fish scale to measure this.


Respect my authoritah!

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After have more than one packer tell me my main closing loop was too loose, I just checked with the Relative Workshop about what they recomend for main pin pull tension in Vectors. They said 5-7 pounds was good, with a maximum of 12lbs. That's far less than it takes to lift my 27lbs rig off the floor. It was fairly light maybe 3-5lbs. I tightened it up a bit, and now have around 7-10lbs pull tension on it ;)

Cheers

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“The maximum force exerted by the
bridle on the curved pin must not be more
then 6 daN. For Safety the minimum force
exerted must not be less then 4 daN."

1 daN = 1 deca Newton which is about 1kg



That puts it in the 9lbs to 13lbs range.

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From the Aerodyne Icon manual:

“The maximum force exerted by the
bridle on the curved pin must not be more
then 6 daN. For Safety the minimum force
exerted must not be less then 4 daN."

1 daN = 1 deca Newton which is about 1kg

You can use a fish scale to measure this.



I think it would be easier to say "so many pounds" or "so many kg." I have never seen a fish scale in daN.:S

Most of what it takes to pull your pin from the loop has to do with new style of protective flap causing resistance on the bridle. If the bridle has an unrestricted pull on the pin it does not take more than 10 pounds to pull the pin if you did not use tools to close the rig. No matter how tight the loop is.

Sparky
My idea of a fair fight is clubbing baby seals

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I think it would be easier to say "so many pounds" or "so many kg." I have never seen a fish scale in daN.:S


A fish scale cannot be correctly marked in Kg. Kg is a measure of mass; fish scales measure force. In order to measure mass you need a balance scale.



Since you started getting technical, I'll chime in. A balance doesn't measure mass either. Since it relies on gravity, it measures weight. Take a balance to the moon and see if it reads the same. Nope. Now an oscillating spring will measure mass. that is what the astronauts use when in space.

Anyway, scales that measure in kg, or N, or pounds (force or mass) or slugs, are all equally useful, if you stick to using them near the surface of the earth, where g doesn't vary much.

Having said all of the above, mostly useless stuff, I can live with N, kg, our pounds on a scale. I'm not keen on the kpf or whatever it is that the cypres people use though.

-- Jeff
My Skydiving History

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A balance doesn't measure mass either. Since it relies on gravity, it measures weight. Take a balance to the moon and see if it reads the same.



Sorry, but a balance will measure the same on the earth, the moon, or the surface of the sun (at least until it melts ;)). It is comparing a known mass to an unknown mass, and the local gravity doesn't matter, of course there needs to be some gravity, so it won't work in uG (micro-gravity, i.e. floating in space).

These are two true balances:
http://www.ohaus.com/products/glo/scripts/view/viewproduct.asp?Recno=710-T0
http://www.ohaus.com/products/glo/scripts/view/viewproduct.asp?Recno=1450-SD

I love useless info :ph34r:.

~Droid

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Question - Is it possible for a closing loop to be to tight? Meaning that it would actually not get pulled out at deployment time?



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It is possible for your closing loop to be too tight.
From the manual : “The maximum force exerted by the
bridle on the curved pin must not be more
then 6 daN”
If you exceed this you will have a pilot chute in tow. This will most likely happen if you deploy sub terminal such as when you do hop n pop.

The pull force on your pin is dependent on:
>Size of the pilot chute you use.
>Type of pilot chute (ZP or F1-11 and mesh size)
>Air speed during deployment

My advice is to have a rigger adjust your closing loop until you are very sure that you can do it yourself.




Respect my authoritah!

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Question - Is it possible for a closing loop to be to tight? Meaning that it would actually not get pulled out at deployment time?



If the PC is in good shape and properly cooked it's very unlikey. A 28" z-po at terminal will pull with a force of 720 N about 73 Kgs or 160 LBS.

The vast majority of PCs in tow are due to uncooked PC or too short kill lines, or too small PCs at sub.
Memento Audere Semper

903

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I have been jumping a J4 for about 3 years. Sometimes my rigger adjusts the length of my closing loop for me. Last week I used a packer for the first time in about six months and he changed my closing loop when I was in a class. The replacement has more play in it than the last one did. What is the proper tension?



Once you've learned how to close the rig without relying entirely on brute force, as tight as you can make it without

1. Requiring a positive leverage closing device which could bend the pin

2. Making your ability to close the container dependant on humidity and pack job consistancy

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