ScratchTX 0 #1 August 17, 2003 This is kind of the opposite of the "line dump with loose stows" discussions here. Can Dacron lines significantly slow down a canopy's opening? Someone told me that it possibly could, because of the added friction of the lines and the bigger line bights. I don't really see that -- I mean, maybe by a fraction of a second. But it seems that, given the snatch force of a good PC, the "bag out" to "line stretch" part of the opening sequence wouldn't really be that affected by line type. And considering how small a part of the entire opening sequence time it takes for line stretch to happen, I just don't see really perceiving much of a difference there... Informed opinions/explanations on this? (I'm of course talking NON-high performance canopy here -- Spectre 150 loaded well under 1:1 -- in case that makes a difference... though I don't see how it would for opening speed) --Scratch Quote Share this post Link to post Share on other sites
diablopilot 2 #2 August 17, 2003 As you stated the friction of the lines and the bigger bites on the stoes, are not that much of a factor. I don't think Dacron slowes openings as much as it "cushions" them. Dacron streches alot compared to Spectra, or other microlines, and absorbs some of the opening shock.---------------------------------------------- You're not as good as you think you are. Seriously. Quote Share this post Link to post Share on other sites
slotperfect 7 #3 August 17, 2003 QuoteI don't think Dacron slowes openings as much as it "cushions" them. Dacron streches alot compared to Spectra, or other microlines, and absorbs some of the opening shock. I second that! Arrive Safely John Quote Share this post Link to post Share on other sites
skydiverek 58 #4 August 18, 2003 QuoteAs you stated the friction of the lines and the bigger bites on the stoes, are not that much of a factor. I don't think Dacron slowes openings as much as it "cushions" them. Dacron streches alot compared to Spectra, or other microlines, and absorbs some of the opening shock. Plus, Dacron has more friction, so the slider descends little bit slower on these lines. This, combined with the lighter weight of brass slider grommets (instead of heavier stainless steel which can build more mommentum on their way down) may produce slightly slower/softer openings. Quote Share this post Link to post Share on other sites
GroundZero 0 #5 August 18, 2003 Dacron absolutely cushions the opening shock. For the most load per time, dacron takes a very heavy and fast loading and simply stifles the force. This is one of the reasons that we now build ALL lower control lines of nothing but DACRON. Not only will dacron rebound with forces, it is the most durable fiber available... get it dirty, abuse it, etc. and it will always outlast every other line by a long shot. Dacron is one of the strongest lines out there... if you can look past the size Chris Quote Share this post Link to post Share on other sites
PhillyKev 0 #6 August 18, 2003 I remember reading on here somewhere a very good explanation regarding the physics involved in snatch force and opening shock, and how the miniscule amount of line stretch you get from dacron in relation to those forces has absolutely no impact on the forces felt during opening. It was pointing out that line stretch making openings softer is an urban legend like the 45 degree exit separation thing. Quote Share this post Link to post Share on other sites
diablopilot 2 #7 August 18, 2003 Quoteis an urban legend like the 45 degree exit separation thing. And if you think THAT is urban legand, I'll be exiting AFTER you, thanks. ---------------------------------------------- You're not as good as you think you are. Seriously. Quote Share this post Link to post Share on other sites
billvon 2,435 #8 August 18, 2003 >And if you think THAT is urban legand, I'll be exiting AFTER you, thanks. The 45 degree thing? There are people who actually still use that? Quote Share this post Link to post Share on other sites
diablopilot 2 #9 August 18, 2003 And why not keep that in your bag of trick to help people understand why seperation is important?---------------------------------------------- You're not as good as you think you are. Seriously. Quote Share this post Link to post Share on other sites
billvon 2,435 #10 August 18, 2003 >And why not keep that in your bag of trick to help people understand >why seperation is important? Because it doesn't work. The previous group never gets to 45 degrees, and the angle they finally make does not depend on upper winds, which is the reason you need to leave more time. You might as well tell people to go when the group ahead of you turns their first point; it would work just as well (i.e. it wouldn't, unless you got lucky.) Quote Share this post Link to post Share on other sites
GroundZero 0 #11 August 19, 2003 Hey.... think of it as time versus force... not stretch distance versus the force... Chris Dacron tames even the wildest beasts! Edited to add some letters (like all of them!) Quote Share this post Link to post Share on other sites
diablopilot 2 #12 August 19, 2003 I disagree, it works well enough. If you're in the door measuring the angle with a protractor then maybe you're taking too long, but with the smaller groups, higher speeds, and reduced awarness younger freeflyers (or jumpers perieod) I'd rather they err on the side of saftey. Teaching people to climb out after 5 seconds is just plain asking for an accident, and teaching awareness about all factors (exit speed, winds aloft, multi directional/speed winds, groundspeed, group size, group type, ect.) takes time. If I can start someone on the road of saftey by telling the 20 jump wonder who may count really fast cause he's excited that's exiting behind me that I've never met before, to wait at least a count of 6 AND look for our group to be out at about a 45 degree angle, that's what I'm gonna do. What do you suggest?---------------------------------------------- You're not as good as you think you are. Seriously. Quote Share this post Link to post Share on other sites
mjosparky 3 #13 August 19, 2003 QuoteI remember reading on here somewhere a very good explanation regarding the physics involved in snatch force and opening shock, and how the miniscule amount of line stretch you get from dacron in relation to those forces has absolutely no impact on the forces felt during opening. It was pointing out that line stretch making openings softer is an urban legend like the 45 degree exit separation thing. If you don't believe it, try jumping the same canopy one time with spectra and the next time with nylon lines. Nylon is even more dynamic then dacron. You will not believe the difference. The fact is, the more dynamic the line, the less opening shock is transferred to the load, ie. jumper. SparkyMy idea of a fair fight is clubbing baby seals Quote Share this post Link to post Share on other sites
