Pull force for pin

[guest]

I noticed that if you are to ball up with a 2 pin rig it seems you can get the pin to be extremely tight. The guy recently at the Perrine was tucked up if I remember correctly. Could that be why? How many pounds is exceptable for that? I was thinking of getting something to measure force to get the exact amount...

Where do you seat your pins on pin rigs? Mine I put half way through just because I worry about it too much.

[BASE_689]

I own and jump a single pin rig (Prism). Because of the "pilot-chute-in-tow" fear, after my 1st jump with it, I removed the original loop ("2A" material, I guess) and I put in service a closing loop of the right length but made out of Cypres loop material (I do not advice that, it's simply my very personal choice).
With such an implementation (and considering that I am a pretty consistent packer), with rig packed, closed and donned (measured by another person using a portable spring scale), I get a pin pulling force of 1÷2 kg - 2.2÷4.4 lb, even lower than the force required to the bridle to clear the "bridle tuck flap" (underneath flap #1 of my Prism), that is about 2 kg - 4.4 lb.
Some could argue that a pin pulling force of only 1÷2 kg - 2.2÷4.4 lb is too low, but I could answer that the covering system of closing loop on my rig is quite secure, so, paying all the time the right attention and care, it is nearly impossible to snag the pin out of its place (by pulling unintentionally the bridle).
When I close my container, I place my pin near the end of its "run", but always confirming (by hand) that it can slide back and forth from its "near-to-the-end" position. Again, I leave quite a good amount of bridle slack (from pin towards canopy) not tucking it immediately under the right flap but tucking the bridle under the right flap after about 8÷10 cm - 3÷4 in of "vertical" path.
The bottom line of jumping a pin rig is that you have got to be a very consistent packer, because the (different) ways by which you fold your "bundled" canopy into your container could vary greatly the pin pulling force.
My 0.02: try to have measured (with your rig donned) your pin(s) pulling force in different situations of tightness of webbings and of packings. Always put the right size of canopy into the right size of container. Always use the right material and the right size (=length) for your closing loop(s).

Stay safe out there
Blue Skies and Soft Walls
BASE #689 :D

P.S.: A portable spring scale costs few $ and is available in any (good) hardware shop.
P.P.S.: Remember that the "true"/"actual" value(s) of pin pulling force can be measured only by another person with your rig donned and all the webbings/straps closed and tightened in a "ready-to-jump" manner (otherwise you would get only "statistical" values, not realistic indeed...).

[guest]

Second question--does anyone have exact pull forces for different PCs at different delays?

[BASE_689]

>Second question--does anyone have exact pull forces for different PCs at different delays?

They do not exist the exact pull forces.
They do exist the theoretical values of pull forces for different PC's at different delays, theoretical values that can be taken to "actual"/"reasonable"/"sensible" values of pull forces by the introduction of a "diminishing factor".
Still the ratios between pull forces of different sizes of PC's remain valid at any delay (provided that each PC at each delay inflates properly (having so delays of at least 1"), does not fall into any burble, is properly manufactured, etc etc).
#698, send an e-mail that I shall send you an Excel table with all the above values, and together with it the value of "my" diminishing factor (completely arbitrary), but that can varied as you please. My e-mail is base_689@yahoo.com

Stay safe out there
Blue Skies and Soft Walls
BASE #689 :D

[guest]

Regarding cypres loops....

I don't jump a pin rig, but as a rigger have extensive experience with cypres loops, and one thing has always struck me a little weird when I hear about people using cypres loop material (to have lower pin-pull forces, I am assuming), as opposed to Spectra/Microline.

It seems to me that a spectra loop would have less friction than cypres loop material. Spectra has a MUCH "slicker" finish on it than cypres material does. While 825 Spectra is about 3 times as thick as cypres loop stuff, 500lb Spectra is similar in diameter, and it would seem like that would provide the best in low pull forces.

In actual use on reserves, cypres loops are pretty slippery, but only after they are lubed up with that silicone gel stuff. I believe that loops from the factory are already impregnated with a small amount of the goo, but anything right off the roll is the texture of dacron. Which are you guys using? Does cypres stuff actually provide lower pull forces than various flavors of spectra?

[imported_Tom Aiello]

When I first get a new pin rig, I always go through a strange little ritual. I pack the rig up, and (on video, actually) have my roommate use a spring scale to measure pull force in various body positions.

I bring this up because I noticed that you are discussing two different styles of pin rig (a Prism, on the one hand, and a two pin rig, on the other).

My observation (based on pull forces of my Perigee Pro and Prisms) has been that the pin tension of two pin rigs, especially the bottom pin, alters significantly more than the pin tension of a one pin rig in different body positions.

In other words, the tension of my Prisms has never varied more than about five pounds in either direction, regardless of body position (unlike 689 I use either standard closing loops--about twelve pounds of extraction force, or small spectra loops for free fall under 200'--about four pounds of force).

However, the tension of the bottom pin on my Perigee Pro varied by as much as 9 pounds depending on body position. Maximum pull force was achieved in a hard tuck. This tends to agree with the observed evidence from last weekend in Idaho, as I believe Huckin' Idiot would rather be burned at the stake than jump non-CR gear, and he was reportedly tucked at the time of the PC hesitation. This is especially important to note when the bottom pin extracts first (to my knowledge all two pin rigs except the Vertex), as this places the point of maximum pull force at initial extraction (and hence doesn't allow container loosening from alternate pin extraction to reduce pull forces).

One experienced jumper I know theorized that the reason for the increased bottom pin tension is the relative location of the bottom pin to the harness geometry. Because the pin is more closely in line with the leg strap webbing, tightening the leg straps may have a greater impact on that pin.

I guess my point is that you should go out and get a spring scale, and really measure your rig, on your body, in various position. All rigs are not created equal, and neither are all jumpers.

--Tom Aiello
tbaiello@mac.com

[imported_Tom Aiello]

>Where do you seat your pins on pin rigs? Mine I
>put half way through just because I worry about
>it too much.

I always seat my pins halfway, and point them up. I recently discussed this with a major gear manufacturer, and was told that there is no recommended direction to face the pins, but that they should always be seated halfway.

I think the only time I'd consider seating them further would be for a very long delay (say, a wingsuit flight from 3000+ ft). I've had no trouble with a single pin, halfway, even on my back at 13 seconds.

--Tom Aiello
tbaiello@mac.com

[346]

I'm using Cypres loop material (polyethylene) straight from the roll on my 2-pin rig. I've been using it on reserves that way for several years.

From my experience packing reserves, Cypres loops are slicker than Spectra - especially with tight reserves where the loop is under a lot of tension. Spectra tends to flatten out when under high tension which increases friction to some degree.

I quit using the Cypres goo several years ago because, while it seems very slippery when you have a large amount of it, as it wears thin it becomes more sticky than anything.. Try rubbing some between your fingers for a 10-15 seconds while rubbing your clean fingers together on the other hand. When it becomes sticky it likes to collect dirt and other contaminants which can be abrasive and start cutting the loop.

Mark &-)