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sundevil777

Dacron lines are good not just because they absorb more shock

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The relative stretchiness of dacron lines I believe is fairly well known, and important.

I think there is something about the friction between dacron lines and slider grommets that is "just right".
Ever since I've had my Pilot relined with Dacron, it has been "just right". I don't know if it is as simple as coefficient of friction or if it is a more complicated relationship with other properties, but I think dacron lines make it easy to get nice openings. I think that slippery line types, such as spectra make it more uncertain because of their different frictional or other properties. I have no experience at all with other types of lines, perhaps they also provide that just right interaction with the slider grommets.

I think more of us that jump larger canopies should consider dacron when a reline is needed. Dacron's ability to not get snagged on velcro or other such similar natural or synthetic materials is also really nice. I always felt like I was destroying my lines when they would get snagged on some velcro from my jumpsuit wrist cuffs, or some vegetation that would get snagged...

Anyway, I think early canopy designers benefited greatly from the good characteristics of dacron rubbing against grommets, and we would be grateful if other line types had that just right relationship, even if they weren't stretchy.

Just a random ramblin, what do you think?

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On 4/21/2019 at 1:37 AM, sundevil777 said:

The relative stretchiness of dacron lines I believe is fairly well known, and important.

I think there is something about the friction between dacron lines and slider grommets that is "just right".
Ever since I've had my Pilot relined with Dacron, it has been "just right"...

My 140 pilot has also been just right since I had it relined with Dacron. Love the combination.

It wasn't a fast canopy to begin with, so I don't mind the performance loss. The openings have become perfect.

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5 hours ago, Sobakin said:

Fricrion is a linear function of pressure, higher contact area = lower pressure. So if fricrion coefficient of material is the same, the total friction force will be the same on thin and thick lines.

In theory, friction is proportional to the force normal to the surface, not the pressure. However, that theory would prevent drag racing from achieving the amazing accelerations they do in fact achieve, so there is more that can go on besides the simple friction model. That is why I say that it may be a more complicated relationship that defies simple analysis of what the theoretical coefficient of friction is for the different materials.

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