I am looking for some information on composite parafoils. Please don't refer me to the search function as there are but two posts on the subject matter on DZ. I am just curious whether the technology is already trickling into the skydiving world. The atair material, which has been tested by some lab at the University of Alberta, is supposedly 300% stronger 600% less stretchable and 68% lighter then ZPO nylon and is on top of that mildew and UV resistant. That seems like a very promising material for canopies. Of course the thing might be more susceptible to abrasions, maybe heat, maybe the strength of ZPO nylon is sufficient and the material is just overkill, some suggested that stretch is good because it softens the opening, who knows; I don't, but I'd really like to (From what I can tell it seems that apex base is selling atair canopies that are partially made with composite material. Interestingly, it is suggested that these canopies should not be jumped more then 200 times [where 300 hundred jumps seems to be the recommended max life for ZPO base canopies]. What are the ups and the downs of canopies made from composite materials (apart from the as of yet prohibitive cost and the potential shorter life of the material)? Anecdotes, discussion, links or any other contribution is appreciated
600% less stretchable... some suggested that stretch is good because it softens the opening, who knows; I don't...
The industry knows, and they're correct. That's why parachutes aren't made out of something like kevlar, that is super-strong, but has no elasticity. And if the opening shock isn't absorbed by stretchy fabric and lines, guess where it goes - down to you in the harness. Even kevlar lines were problematic on military ejection chutes, causing harder openings. And then you have to figure out how to sew a non-elastic line to an elastic fabric - the two don't mix well - that creates a failure point.
I think you are missing something here. Atair, the company from Slovenia has been selling base canopies with a low bulk Nylon fabric made in France. The US based Atair in New York built one 9 cell skydiving main some years back out of the "300% stronger " material to try it out. Apex is making canopies with the same weight fabric as the French Nylon fabric that the Slovenian Atair is (Think PD Optimum resv.). The US Atair and Slovenian Atair are not related anymore. You can look on "basetroll.com" and "apexbase.com"
(This post was edited by PeteS on Nov 4, 2009, 7:37 AM)
No! Atair's experimental program - with the University of Alberta - was primarily aimed at making ribs the same way as sails on high-performance racing yachts. The goal was to orient threads in the fabric with stresses in ribs. Conventional ribs do this with tapes sewn on after ribs are cut, while Atair was trying to glue together threads to form ribs. Great idea in theory, but would be frightfully expensive to manufacture.
And to clarify, the term "Para-Foil" is only used on one model of ram-air parachute manufactured by North American Aerodynamics. The "Jalbert Para-Foil" is only used by precision landing competitors, a narrow niche of the skydiving world. Using the term to describe any other canopy will confuse readers.
Dan gave a talk at the last PIA about this material. He built a canopy out of it (a Cobalt I think.) It wasn't idealized (i.e. did not have the fibers laid out in loadbearing directions) but it was considerably lower bulk.
It didn't fly very well though. When you look at the top of any skydiving canopy in flight, you see it bulge upwards where the fabric is stretching, creating more of a curve on top of the airfoil. Designers plan for this, and the curve becomes an essential part of the airfoil. When you use a more dimensionally stable fabric (like Atair's layered composite) you don't get that stretching, and thus the same plans do not work well for the new fabric.
Dan also mentioned that such a canopy would be insanely expensive to manufacture. However, if enough people wanted them, you could:
1) Orient the fibers to take the load through the line attach points, reducing bulk even further
2) Redesign the canopy patterns to account for the lack of stretch.
such a canopy would be insanely expensive to manufacture
everything was too expensive in the beginning, unaffordable to majority.
In Reply To
you see it bulge upwards where the fabric is stretching, creating more of a curve on top of the airfoil. Designers plan for this, and the curve becomes an essential part of the airfoil.
I tend to beleive that designers have been rather empirical than innovative
so what you say, I beleive will happen:
Quote
Redesign the canopy patterns to account for the lack of stretch.
>everything was too expensive in the beginning, unaffordable to majority.
Of course. And some designs (like the ZP-based ram-airs) got cheap enough to use; some (like rigid deployable wings, or high pressure inflatable wings) never did.
>I tend to beleive that designers have been rather empirical than >innovative . . .
Definitely. Modeling inflatable wing surfaces is very tough; most parachute designs go through a lot of empirical testing.
It didn't fly very well???? It flew great! better than one made of zp. And the canopies for powered parachutes really out performed zp canopies as well. It was strange to pack but it opened and flew very well. It just cost a lot!
