To upgrade the stiffeners in the leading edge of parawings from nylon to nitinol, what wire to choose? I sail in temperatures between 7 and 30 centigrade. So i presume that i need nitinol wire 0 degree centigrade (37 F) in 1mm oxidation free, could that assumption be correct? Does anyone know where to get that in small quantities, like 10 meter? The only oxidation free i can find is sold in a minimum of 2 kilo at Nextmetal Corporation, they have it in many temperature variations. There is also chaostrade.eu , a company in eastern europe that sells small quantities, but they do not say if it is oxidation free, and the temperaturesetting is above my use, so i presume it would not be useful for parawinging. Maybe to prevent oxidation it would be possible to paint it with 2 component DD coat? To put caps on the sharp ends i was thinking of using a drop of epoxy with a tiny bit of chopped fiber. Maybe these can also be used in wings to replace the battens in the trailing edge? Comments?
You want superelastic, not shape memory
Sorry I didn’t read all the details on the first pass… The oxide finish is not a problem, it is a smooth shiny black finish and will not corrode. Normally nitinol is available in shape memory or superelastic grades. It’s been a while since I’ve worked with it but I believe “superelastic” grade is typically 0c to -20c transition temp. Unless you are going to be snow parawinging any wire sold as superelastic should be fine. Commercial quantities are expensive, but check ebay for remnants or you might even find free samples available if you talk to the right sales rep. In the USA Fort Wayne metals is (or was) the main vendor but this might have changed and I’m not sure about EU
Presume you’ve already listened to the interviews w Ewan Jaspan who designed the Hatch v2? He has discussed the difficulties with incorporating Nitinol a few times - specifically how hard it was to keep the battens from poking through the fabric. Maybe the epoxy trick will work, but sounds like it took them a bit of R&D to figure out. If you haven’t it might be a worthwhile listen before embarking on this project.
<intended to respond to the op, not the prior poster>
One approach to the tips might be to heat set the tip back on itself. It’s not too hard but does require a high temp furnace (around 500c).
you could 3d print little end caps
I heard this segment. I interpreted it not that it is fundamentally a hard problem, more that it was a painful learning. After putting so much time into building a prototype to realize it had this shortcoming and having to do a whole another round of prototyping. Solving the “problem” is rarely difficult in engineering - identifying the problem is usually the hard part. I agree with the suggestions above, it should be perfectly find to 3D print some caps and move on.
I would guess though that once you buy the super elastic nitinol, it needs to be formed to the correct curve shape, which won’t be an easy DIY problem. It needs to be constrained into shape and then re-heat-treated up in the area of 1000F oven. Well beyond hobby equipment here
Yes i know the interview, super interesting to hear all that, putting a drop of epoxy on nitinol is probably not fast enough for industrial use, they want caps, but for a person willing to put some effort in, it is a different story. But maybe they even tried epoxy and it was no good…
“Forming the 1mm nitinol wire to a correct curved shape”: i should take one out of my hatch v2 to see what shape it has, or if it just springs into a straight shape when it comes out of the dacron pocket. I had the assumption that it was just straight and springy, but your words made me realize now that it might be different…
straight nitinol wire works fine, will bend nicely into shape of the leading edge, no heating and shaping needed.
Hi,
You can buy it in small quantities on Amazon, and no need to thermoform it. A straight wire follows the batten pocket sown into the wing. The diameter is small, your leading edge will rip if you drag the wing on the ground and the wire will poke out unless you put in some sort of end thingy.
br,
Chris
Does that no dragging rule go for the production models as well? Not that anyone would intentionally do that but accidents do happen.
If those battens are straight that would explain why the leading edge is so rock solid while flying the wing. Of the parawings I have tried or flown, my two favorite in terms of feel are the Hatch v2 and Core Lotus. I’m very VERY happy with my Hatch v2 quiver and think Nitinol will (or should) be universally used in all parawings.
There is some tension where the bend is the sharpest, (in my hatch v2) so i imagine that if the battenpocket would have a large open scratch and then the leading edge would smash into something, that the batten might poke out, but poking out can happen with nylon stiffeners too.
Can we try some traversal wire to stiffen the shape further? If it’s so good then bundling it shouldn’t be a problem? I would imagine I’m gusty conditions collapses and backstalling could be improved if it’s forced into full wingspan. Stash then becomes a new fight
I could also imagine stiffening the lines to make them unravel more easily if tangled.
Oh that’s a totally new take on the entire concept of parawings. Before we all start commenting about how hard that is to stash, it should be tried, tested, in a few different configurations. We all like the feel of new fresh lines, they have a certain stiffness in them from factory, and after a year or so the factorywax has partly disappeared (or cracked) and then the lines are softer and tangle a bit more, so from that perspective maybe it is not so crazy to have superthin nitinol stiffeners inside the dyneema lines. (maybe only 0,2mm thick) And as you say maybe also in the entire shape of the canopy, if it is flexible enough to stash easily then who knows what the possibillities are. It is great to see so may ideas here!!!
Maybe cable end caps for mechanical bike brakes or shifter cable could be the easiest solution?
gotta be resistant to corrosion
On the Frigate 5.5, the ears have traversal rods on the last few cells, presumably to keep the ears more open when redeploying. Hard to tell if it’s effective without proper A/B testing, but I suspect Nicolas added those for a reason.
I wanted to add rods like that on the LE of the Takoon Zenith to fight its dreadful tendency to self concertina as soon as you release some pressure on the B and Cs, but never got around to it. That thing is probably a lost cause…