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Deisel

Cold Weather effects?

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Well there is plenty of info regarding the effects of hot weather on a rig/cypress/canopy etc. What about the cold? Does leaving a rig in the car in freezing weather have any adverse effects?

D
The brave may not live forever, but the timid never live at all.

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I highly doubt that it would affect the rig/parachutes, except if anything was damp/wet. If it was all dry, things get stiff, but not enough to cause problems. The biggest problem is loss of feeling in your hands. Ask and Canadian...some of us do jumps all winter long and it's the same as summer, only colder. I'm exited from a Cessna at 10 grand while it was -12 celsius (10F) on the ground...-30 Celsius at altitude (-22F). It's pretty unpleasant, but everything works...except your hands.

As for a cypres...batteries freezing are NOT good. I wouldn't want it to explode and spew battery acid all over my reserve...eating away at it until the next repack or use and it desintegrates.

Here is a god example of what happens when your pilot chute is "damp" and you jump in cold weather. It's a base jump (not me), but it's pretty scary. You can see how the PC is frozen together and almost costs this man his life.


http://ca.youtube.com/watch?v=Uqivh3meJOM
"When once you have tasted flight..."

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>As for a cypres...batteries freezing are NOT good. I wouldn't want it
>to explode and spew battery acid all over my reserve...eating away at it
>until the next repack or use and it desintegrates.

Primary lithium batteries do not 'freeze' and rupture like, say, a flooded lead acid cell would. At low temperatures (below about -20C) they start seeing significant degradation in power output, and below about -40C they can't put out any significant power. But they'll still work when they warm up again.

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Jumping in colder temps I have had noticeably slower openings. Is there any concern of a (dry) canopy freezing? Has anyone looked at the differences in the behavior of frozen nylon (ZP v F111)?
The brave may not live forever, but the timid never live at all.

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Well there is plenty of info regarding the effects of hot weather on a rig/cypress/canopy etc. What about the cold? Does leaving a rig in the car in freezing weather have any adverse effects?

D



Parachute parts that have been TSO'd under C23c and C23d have practical tests that must be met. On the cold side, parts must be stored at a temp of no greater the -40F for no less than 16 hours, then brought to ambient and immediately drop tested. On the hot side, parts must be stored at a temp no less than 200F for no less than 16 hours, then brought to ambient and immediately drop tested.

I am not sure how definitive the results are, since the parts arent dropped at -40 or 200, nor is ambient defined, so take it for what its worth.

On a side note, there have been jumps into the north pole, Antarctica, and recently the Everest jumps. I would think it safe to assume that the greater majority of us do not jump in as harsh of conditions. Lets also not forget about high altitude miltary jumps that deal with freezing temperatures.

On another side note, after a quirk with my Argus, I stored it in the freezer for 48 hours, and then cycled it while frozen. As frosty as it was, It went through its normal start up and appeared to work normally, though, I was not jumping that day and cant attest to the longeivty of the life of those batteries, which have since been replaced.

I guess the point I am trying to make is, if you leave your rig in the trunk of your car, the least of your concerns should be the temperatue.
________________________________________
I have proof-read this post 500 times, but I guarantee you'll still manage to find a flaw.

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AS8015B

4.3.3 Compressed Pack and Environmental Tests: Three drops shall be made to the lowest applicable direct drop speed in 4.3.6 except that prior to the test the parachute assembly shall be subjected to the
following preconditioning: (These tests may be combined with other tests.)

4.3.3.1 Precondition for 16 h at not less than +200 °F (93.3 °C), stabilize to ambient and test drop.

4.3.3.2 Precondition for 16 h at not greater than -40 °F (-40 °C), stabilize to ambient and test drop.

4.3.3.3 Precondition for not less than 400 continuous hours with a 200 lbf (889.6 N) or greater load applied to compress the pack in a manner similar to that most likely to be encountered in actual use. Test drop within 1 h after removing the load.

Main Entry: ambient
Function: noun
Date: 1624
1 : an encompassing atmosphere :

Sparky
My idea of a fair fight is clubbing baby seals

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Main Entry: ambient
Function: noun
Date: 1624
1 : an encompassing atmosphere :



That still doesnt define what ambient IS. We could be dropping it on a nice hot sunny day in Florida (likely) or a blistering cold day in Wisconsin (not-likely).

Unless, I am missing something important, what is the goal of freezing the parts for 16 hours, thawing them, then dropping them? Other than perhaps part embrittlement, what can freezing, then thawing, tell us? I'd be more interested to see if the cold weather plays a role in part rigidity during use.

I'd be interested to hear from the FAA types or manufacturers, unless I truly am missing something fundamental.
________________________________________
I have proof-read this post 500 times, but I guarantee you'll still manage to find a flaw.

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