Forums: Skydiving: Gear and Rigging:
Cutaway cables

 


phorty  (D 25563)

May 23, 2001, 6:21 PM
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Hi everyone,

I exercised my three ring release system today for the first time on my newly aquired rig and noticed that the cable clears the loop on the right risers before the left side does. In fact there appears to be another couple of inches of cable to go on the left side when the right side releases. I thought that all the rigs releases were custom made and as such should release at the same time for a stable chop and reserve deployment. What do ya'll think? Should I have my rigger correct the problem before I jump it again(which could be a while) or ASAP? Thanks!



PalmettoTiger

May 23, 2001, 8:28 PM
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Any problem with your gear's emergency systems requires immediate attention.

Blues, squares,
PTiger


skymedic  (C 33561)

May 23, 2001, 10:42 PM
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Do it now, its not worth even a fraction of a risk...



Geoff

May 24, 2001, 12:16 AM
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This may be a deliberate design feature.

If your rig is designed to have an RSL on the left riser (even if there isn't one fitted now), then the right riser should release before the left one.

2 inches sounds like a big difference, though - as always, it's best to check with a rigger.

Geoff



Premier slotperfect  (D 13014)

May 24, 2001, 2:53 AM
Post #5 of 16 (1395 views)
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Geoff is right. The RSL riser should release last. Your rig is fine! He is also right about the cutaway cable length being custom fit to each rig. I know that Javelins and Vectors are built that way. Of course, if you lose your cutaway handle and replace it with a new one, you may have to trim the ends to get it to fit correctly. Your Rigger can do this for you with a pair of cutters and a lighter. Kudos to you for being that observant!

Respectfully,
SP


DBTECH  (B 21186)

May 24, 2001, 10:10 AM
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Yes, you want a guaranteed first right side release first with an RSL in use.
In my mind with a two inch longer RSL side cable, along with an aggressive pull/cut away, would translate to about a 65 ms (1/16 sec) second delay after the right side. (I'm assuming a two inch difference (0.166 ft)
Anyone want to make a guess how far the right riser ring is above the harness ring when the left side releases? (assuming an aggressive pull/cut away)

Dave Brownell



cdunham

May 24, 2001, 10:23 AM
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4cm?


DBTECH  (B 21186)

May 24, 2001, 10:38 AM
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You say 4cm or 1.6 inches; I say more.
Also, one must consider the type of malfunction.

Dave Brownell



cdunham

May 24, 2001, 11:07 AM
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This was a quicky calculation assuming no relative speed difference, i.e how far would you fall from rest in 1/16 sec?

10 m/s^2 * (1/16)^2 = 0.04m

I would guess that there is some additional upward force (drag) from the canopy, and possibly some angular momentum/centrifugal force if you are spinning.

I am not a physicist, nor do I play one on tv.




cyberskydive  (C 28534)

May 24, 2001, 11:16 AM
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Post deleted by alan


Craig

May 24, 2001, 1:13 PM
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In reply to:
But he did stay at a holiday Inn express last night
Damn, beat me to it!

Seriously though, I am GUESSING about 12in released riser travel as the second riser is being released. I noticed the differences in the cable lengths (from loop to end of cable) when I was inspecting my release system a few months back and chalked it up to design and wanting the RSL side to release first to possibly reduce the risk of reserve PC entanglement. Another consideration besides wanting the RSL riser to release first would be housing flex/strech due to a loaded harness. This might or might not be equal depending on the mal (more weight suspended under the RSL side would strech the harness/housings more on that side which would use some of the cable length as a result. FWIW my RSL side release cable is 1 1/4" longer than the other side.

Craig



DBTECH  (B 21186)

May 24, 2001, 4:04 PM
Post #12 of 16 (1314 views)
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Craig said:

Seriously though, I am GUESSING about 12in released riser travel as the second riser is being released. I noticed the differences in the cable lengths (from loop to end of cable) when I was inspecting my release system a few months back and chalked it up to design and wanting the RSL side to release first to possibly reduce the risk of reserve PC entanglement. Another consideration besides wanting the RSL riser to release first would be housing flex/stretch due to a loaded harness. This might or might not be equal depending on the mal (more weight suspended under the RSL side would stretch the harness/housings more on that side which would use some of the cable length as a result. FWIW my RSL side release cable is 1 1/4" longer than the other side.

Craig

DB> You do mean the "non" RSL side, ideally releasing first.

I would agree with 12" - 36" being a riser release difference figure.

Dave Brownell




Craig

May 24, 2001, 8:29 PM
Post #13 of 16 (1290 views)
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In reply to:
You do mean the "non" RSL side, ideally releasing first.
Correct, one of those days I guessCrazy



alan  (D 17868)

May 24, 2001, 8:38 PM
Post #14 of 16 (1289 views)
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"What do ya'll think? Should I have my rigger correct the problem before I jump it again(which could be a while) or ASAP? Thanks!"

phorty,
You or your rigger should contact the manufacturer for the correct specifications for the cables and how to check them properly. It may vary from manufacturer to manufacturer. My advice would be to do this before jumping the rig.

Be safe,


alan


screwbag  (C 34044)

May 24, 2001, 10:46 PM
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i'm not sure how the tso reads on certain rigs. but i do know that the reserve ripcord is a tso'd item so the cutaway may be as well. master rigger only...and even then it's kind of a grey area... contact manufacturer and find out if the tso applies to that specific part.

blue ones




screwbag  (C 34044)

May 30, 2001, 11:05 PM
Post #16 of 16 (1211 views)
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i checked on yer question today...apparently the cutaway is NOT a tso item because it is not directly related to the reserve system itself...however there is a delay on one side(the rsl riser) so that the last thing that happens in the sequence is that the rsl gets pulled as the main canopy goes away...if the order were reversed there is a chance of the rsl pulling too soon and the reserve pilot chute deploying into a bad main canopy...

hope this helps

blue skies





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