johnmatrix 21 #1 October 27, 2012 Is it possible to create a hard pull from pin tension alone? Or would pin tension just contribute to other possible problems with the cable, cable housing, to cause a hard pull? Of course varying pin tension will require more or less strength to pull the pin, but what would it take to put enough tension on the pin to cause a catastrophically hard pull? Is it possible to close a reserve (e.g with a leverage device) so tightly that a main pilot chute would not be able to pull the pin - e.g via an RSL/Skyhook when cutting away from a high-speed malfunction like a baglock? Quote Share this post Link to post Share on other sites
riggerrob 643 #2 October 27, 2012 According to the American Federal Air Regulations, pull force on a ripcord should be between 5 pounds and 22 pounds. Any more than that is not airworthy, Those pull forces are measured when pulling the ripcord handle in the easiest direction relative to the ripcord housing, so if you tried hard enough, you could increase the pull force by pulling in the wrong direction, (e.g. perpendicular to the end of the ripcord housing). Quote Share this post Link to post Share on other sites
riggerrob 643 #3 October 27, 2012 Quote... Is it possible to close a reserve (e.g with a leverage device) so tightly that a main pilot chute would not be able to pull the pin - e.g via an RSL/Skyhook when cutting away from a high-speed malfunction like a baglock? .................................................................... A collapsed main pilot chute might not pull hard enough (5 to 22 pounds) to pull an RSL/Skyhook. If that happens, you would need to pull your reserve ripcord (just like the old days) or pray that your Cypres is turned on. Sarcastic humour !!!! Quote Share this post Link to post Share on other sites
mark 107 #4 October 28, 2012 QuoteThose pull forces are measured when pulling the ripcord handle in the easiest direction relative to the ripcord housing, so if you tried hard enough, you could increase the pull force by pulling in the wrong direction, (e.g. perpendicular to the end of the ripcord housing). The newest TSO standards (C23c/AS8015A, 1984 and later) say the maximum pull force should be measured in the direction giving the highest pull forces under normal operation. This would probably be straight out from the chest. Whether that would be perpendicular to the ripcord housing would depend on the rig design. For sure you'd get a higher pull force if you tried pulling straight up, but that wouldn't be a normal direction. On the other hand, the 5-pound minimum pull force is measured in the direction of easiest pull. Mark Quote Share this post Link to post Share on other sites
pchapman 279 #5 October 28, 2012 Quote giving the highest pull forces under normal operation. Nice point. Then one gets into whether a weird pull direction is defined as normal operation or not, so the rules aren't very helpful! Just about any pack job could fail the test if one pulls the handle into the harness pocket... Riggers don't try to get a high pull force when testing after a repack; we normally try to get the lowest possible number given the tight rigs today. Quote Share this post Link to post Share on other sites
riggerrob 643 #6 October 28, 2012 Quote... a repack; we normally try to get the lowest possible number given the tight rigs today. ........................................................................ Yes. I normally aim for a reserve ripcord pull-force in the "high teens" ... 17 to 19 pounds. Sometimes an especially tight reserve will test at more than 20 pounds, but it usually settles to the teens by the time I re-measure pull force the next day. Quote Share this post Link to post Share on other sites
johnmatrix 21 #7 October 28, 2012 What do you use to test it without pulling the pin? Quote Share this post Link to post Share on other sites
riggerrob 643 #8 October 29, 2012 QuoteWhat do you use to test it without pulling the pin? ................................................................... A fisherman's scale and a gentle technique. Hah! Hah! It is a gentle technique that all riggers are well-practiced in, but most first-timers will flail miserably. The outcome - of most newbies - resembles an explosion in a pilot-chute factory! Hah! Hah! Seriously, ask your local rigger to demonstrate te technique - for measuring ripcord pull forces - the next time you see him/her during a quiet afternoon. Quote Share this post Link to post Share on other sites
koppel 4 #9 October 29, 2012 There is a tool that prevents the pin from being pulled entirely whilst checking the pull forces with a fish scaleI like my canopy... ...it lets me down. Quote Share this post Link to post Share on other sites
johnmatrix 21 #10 October 29, 2012 Thanks - I know I've seen one somewhere in my travels through online gear stores. I will travel to the sacred loft and ask for an audience with the Great Rigger Equal of Heaven. The Prophecy shall be fulfilled. Shall it not come to pass, I will search online, and upon discovering an image of the secret artifact, state the words 'Oh, that's interesting'. Quote Share this post Link to post Share on other sites
mark 107 #11 October 29, 2012 http://www.paragear.com/templates/base_template.asp?group=162#M5995 Mark Quote Share this post Link to post Share on other sites
theonlyski 8 #12 October 29, 2012 You mentioned a skyhook and I just wanted to point out that the tool linked above probably wont help much because of the different pin used on Vectors. (provided you have a Vector)"I may be a dirty pirate hooker...but I'm not about to go stand on the corner." iluvtofly DPH -7, TDS 578, Muff 5153, SCR 14890 I'm an asshole, and I approve this message Quote Share this post Link to post Share on other sites
ctrph8 0 #13 October 29, 2012 I don't use Cypres silicone very often but one afternoon I played with the idea of whether I could create a hard pull scenario if there was silicone on the very top of the loop. In short, I couldn't. To be fair, I didn't try very many times to do this and was leery of putting my rig through that more than those few times. I never came to any real conclusions other than the thought that it has some effect in the moment and that I didn't know much beyond what I'd seen that afternoon. Has anyone played with this? If so, does anyone know if the effects of the silicone can wear off so that it could be a pull within the limits at the time of packing but get harder to pull later? QuoteIs it possible to create a hard pull from pin tension alone? Or would pin tension just contribute to other possible problems with the cable, cable housing, to cause a hard pull? Of course varying pin tension will require more or less strength to pull the pin, but what would it take to put enough tension on the pin to cause a catastrophically hard pull? Is it possible to close a reserve (e.g with a leverage device) so tightly that a main pilot chute would not be able to pull the pin - e.g via an RSL/Skyhook when cutting away from a high-speed malfunction like a baglock? Quote Share this post Link to post Share on other sites
riggerrob 643 #14 October 29, 2012 No! But I do know that when you spill Cypres silicone lubricant on the floor, it makes for lots of frivolity, pratfalls, slap stick, ... better than bananananana peels ... , etc. Hah! Hah! Quote Share this post Link to post Share on other sites
JerryBaumchen 1,367 #15 October 29, 2012 Hi Mark, You beat me to it. The first time I saw one of these tools was at the Parachutes de France booth at the '93 Symposium. It is my understanding that Dave DeWolf now makes them for people to obtain. I believe he exclusively sells them via ParaGear. JerryBaumchen Quote Share this post Link to post Share on other sites
johnmatrix 21 #16 October 30, 2012 Well spotted sir - thanks. Quote Share this post Link to post Share on other sites
johnmatrix 21 #17 October 30, 2012 Have you ever used it for other purposes? ....more devious purposes? Quote Share this post Link to post Share on other sites
