Forums > Wing Foiling General

Bagging out caused by le/tips stretching, not canopy?

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Created by foilfondler 5 months ago, 6 Apr 2024
foilfondler
30 posts
6 Apr 2024 8:40PM
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Liam on generic said he heard this on a recent episode. Anyone else hear this?

BWalnut
365 posts
6 Apr 2024 9:57PM
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Haven't heard that. Doesn't make sense at first thought but maybe he's dissected it a bit more.

foilfondler
30 posts
6 Apr 2024 10:00PM
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Has anyone noticed a difference in rate of degradation btwn aluula and standard wings?

BWalnut
365 posts
6 Apr 2024 10:20PM
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foilfondler said..
Has anyone noticed a difference in rate of degradation btwn aluula and standard wings?


100%I wont buy a standard wing again.

sunsetsailboards
470 posts
7 Apr 2024 1:29AM
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i've been theorizing this for a couple years now. my original Unit D/LAB 3.5 had over 100 days on it and was still a great wing when I sold it. Canopy was still pretty taut... and then comparing to my friend's regular 4.0 that was also well used (but had fewer days) the canopy was pretty bagged. The canopy material does stretch out and the I think the LE fatigues as well, but I would have thought ALUULA would have exacerbated the canopy bag, but my experience has been the opposite.

YMMV

also all wings are not the same... and perhaps different construction techniques will help with LE shape/stiffness retention

patronus
372 posts
7 Apr 2024 2:08AM
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Someone on here had a worn wing and a new, same model. Measured canopy as same, but the leading edge and tips differed and accounted for the bagging.

BWalnut
365 posts
7 Apr 2024 2:15AM
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patronus said..
Someone on here had a worn wing and a new, same model. Measured canopy as same, but the leading edge and tips differed and accounted for the bagging.


Weird. I'm trying to imagine how that would work? If the canopy hadn't changed how could the leading edge have changed? Frame rolled out and lost shape?

Velocicraptor
619 posts
7 Apr 2024 3:45AM
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BWalnut said..

patronus said..
Someone on here had a worn wing and a new, same model. Measured canopy as same, but the leading edge and tips differed and accounted for the bagging.



Weird. I'm trying to imagine how that would work? If the canopy hadn't changed how could the leading edge have changed? Frame rolled out and lost shape?

There have always been two schools of thought here. Stiffer frame puts more load on the canopy and leads to stretching and bagging. The other school is that the frame changes (maybe camber changes or maybe the tips start to twist) and takes the tension out of the canopy. The measurements referenced above support the later theory. Interesting.

Thatspec
354 posts
7 Apr 2024 2:58PM
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Velocicraptor said..

BWalnut said..


patronus said..
Someone on here had a worn wing and a new, same model. Measured canopy as same, but the leading edge and tips differed and accounted for the bagging.




Weird. I'm trying to imagine how that would work? If the canopy hadn't changed how could the leading edge have changed? Frame rolled out and lost shape?


There have always been two schools of thought here. Stiffer frame puts more load on the canopy and leads to stretching and bagging. The other school is that the frame changes (maybe camber changes or maybe the tips start to twist) and takes the tension out of the canopy. The measurements referenced above support the later theory. Interesting.


I remember that thread as well. It was a repair guy, maybe he'll chime in again.

Hard to imagine the lightweight sailcloth doesn't stretch a little over time. Does make a good case for exotic materials in the LE and strut.

King Crash
NSW, 306 posts
7 Apr 2024 6:17PM
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It's a common misunderstanding: the idea that a worn canopy is to blame for reduced power and flapping leach. Yep, those symptoms are spot on, but it's not the canopy stretching first. The frames take the hit initially, causing the tips to stretch. So, when you see that flapping edge and feel the power dip, it's likely the frames giving in.

Another biggie we've noticed is the lack of consistent loading in the cloth. Ever checked out how the material around the windows gets all saggy and misshapen? That's your proof right there. Using fancy frames and lightweight kite cloth might buy you some time, but it's not a long-term fix.

Only a handful of brands are tackling this head-on, and it might take the industry a bit to catch up. If you're rocking high-tech leading edges, consider laminates with taffeta for durability in the critical areas. As the load eases up, you can switch to regular kite cloth.

Exciting times ahead, let's see where this journey takes us next!

FranP
76 posts
7 Apr 2024 10:58PM
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Select to expand quote
King Crash said..
It's a common misunderstanding: the idea that a worn canopy is to blame for reduced power and flapping leach. Yep, those symptoms are spot on, but it's not the canopy stretching first. The frames take the hit initially, causing the tips to stretch. So, when you see that flapping edge and feel the power dip, it's likely the frames giving in.

Another biggie we've noticed is the lack of consistent loading in the cloth. Ever checked out how the material around the windows gets all saggy and misshapen? That's your proof right there. Using fancy frames and lightweight kite cloth might buy you some time, but it's not a long-term fix.

Only a handful of brands are tackling this head-on, and it might take the industry a bit to catch up. If you're rocking high-tech leading edges, consider laminates with taffeta for durability in the critical areas. As the load eases up, you can switch to regular kite cloth.

Exciting times ahead, let's see where this journey takes us next!


Hi,I've drawn some conclusions regarding the factors that contribute to wing bagging:

1. The materials used in the canopy, particularly in the trailing edge area, are not sufficiently stiff (inelastic), despite significant improvements. I believe this is the primary factor, especially after 50-75+ sessions. It's likely that wing brands will innovate in this area, possibly using Dyneema or other materials to enhance this part of the wing.

2. Over-sheeting while sailing.Impact from waves and wipeouts.

In my opinion, features like stiff leading edges or Aluula frames, although they improve wing power, sailing capabilities, etc, they don't significantly mitigate the bagging out effect.

We need to devise a method to repair or refurbish a used wing after 75-100 sessions without replacing the canopy.

My proposal to refurbish a "long used" wing is sewing a few lines parallel to the battens to stretch the area and restore proper tension to the trailing edge.

What are your thoughts on this?


BWalnut
365 posts
7 Apr 2024 11:51PM
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Could someone define "stretching the tips"? I have a very hard time believing that the tips are stretching, there's so little fabric there. I could believe the frames rigidity is lost and and the tips are rolling out causing deformation, but not stretching.

FranP
76 posts
8 Apr 2024 12:14AM
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BWalnut said..
Could someone define "stretching the tips"? I have a very hard time believing that the tips are stretching, there's so little fabric there. I could believe the frames rigidity is lost and and the tips are rolling out causing deformation, but not stretching.


I guess "stetched tip" means the effect of the picture , which I believe it is NOT an issue as air pressure solves the problem.In my opinion, bag out is due to panels get less flatter and maybe junctures as well.




DWF
609 posts
8 Apr 2024 12:40AM
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This is what's really wrong...

A new 6m windsurf sail is $800 and lasts 5 years.

A 6m Aluula wing is $2000 and lasts 1 year.

A 6m Dacron wing is $1200 and lasts 6 months.

WTF..

BWalnut
365 posts
8 Apr 2024 12:49AM
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Select to expand quote
DWF said..
This is what's really wrong...

A new 6m windsurf sail is $800 and lasts 5 years.

A 6m Aluula wing is $2000 and lasts 1 year.

A 6m Dacron wing is $1200 and lasts 6 months.

WTF..

and then listed as "almost new" on the used market ????

Select to expand quote
FranP said..

BWalnut said..
Could someone define "stretching the tips"? I have a very hard time believing that the tips are stretching, there's so little fabric there. I could believe the frames rigidity is lost and and the tips are rolling out causing deformation, but not stretching.



I guess "stetched tip" means the effect of the picture , which I believe it is NOT an issue as air pressure solves the problem.In my opinion, bag out is due to panels get less flatter and maybe junctures as well.





Interesting, so the theory is that the tips deform in due to canopy load pulling on them? This would argue that a loose canopy at new would be better right?

FranP
76 posts
8 Apr 2024 2:50AM
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Select to expand quote
BWalnut said..


DWF said..
This is what's really wrong...

A new 6m windsurf sail is $800 and lasts 5 years.

A 6m Aluula wing is $2000 and lasts 1 year.

A 6m Dacron wing is $1200 and lasts 6 months.

WTF..



and then listed as "almost new" on the used market ????



FranP said..



BWalnut said..
Could someone define "stretching the tips"? I have a very hard time believing that the tips are stretching, there's so little fabric there. I could believe the frames rigidity is lost and and the tips are rolling out causing deformation, but not stretching.





I guess "stetched tip" means the effect of the picture , which I believe it is NOT an issue as air pressure solves the problem.In my opinion, bag out is due to panels get less flatter and maybe junctures as well.





Interesting, so the theory is that the tips deform in due to canopy load pulling on them? This would argue that a loose canopy at new would be better right?



I don't think tips lose their shape, as the structural air frame is supported by bladder air pressure. The problem is the canopy that gets loose, bag out, etc.

Dspace
VIC, 300 posts
8 Apr 2024 6:22AM
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Select to expand quote
DWF said..
This is what's really wrong...

A new 6m windsurf sail is $800 and lasts 5 years.

A 6m Aluula wing is $2000 and lasts 1 year.

A 6m Dacron wing is $1200 and lasts 6 months.

WTF..




Sorry but I'm going to respectfully disagree with the wing portion of this. I can only speak to my own experience. My SLS Slick quiver (6, 5, 4m) has just gone basically 2 full seasons with maybe a small decease in performance level. It's hard for me to even notice any specific performance loss since it's occurring quite slowly. I learned a bunch of new strapless freestyle moves on these wings well past the 1 1/2 year mark, and I don't doubt that I could get a 3rd season out of them if I wanted to. Maybe my skills aren't good enough to recognize the loss in performance

That being said I am upgrading to DLab slicks this year,..well,..because I can

DWF
609 posts
8 Apr 2024 5:25AM
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Select to expand quote
Dspace said..

DWF said..
This is what's really wrong...

A new 6m windsurf sail is $800 and lasts 5 years.

A 6m Aluula wing is $2000 and lasts 1 year.

A 6m Dacron wing is $1200 and lasts 6 months.

WTF..





Sorry but I'm going to respectfully disagree with the wing portion of this. I can only speak to my own experience. My SLS Slick quiver (6, 5, 4m) has just gone basically 2 full seasons with maybe a small decease in performance level. It's hard for me to even notice any specific performance loss since it's occurring quite slowly. I learned a bunch of new strapless freestyle moves on these wings well past the 1 1/2 year mark, and I don't doubt that I could get a 3rd season out of them if I wanted to. Maybe my skills aren't good enough to recognize the loss in performance

That being said I am upgrading to DLab slicks this year,..well,..because I can


Differences in riding styles here. I'm going upwind, then surfing down wind the whole session. Fully loaded in a kite harness. Draft stability gone in 6 months. The Gorge, kills a wing in just weeks. I summer there.

miamiwngr
63 posts
8 Apr 2024 6:22AM
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I believe the bladder is just a straight tube so the pressure would work to deform the frame over time (supporting the theory that bagging primarily comes from frame and not canopy)

King Crash
NSW, 306 posts
8 Apr 2024 9:01AM
Thumbs Up

Select to expand quote
FranP said..

King Crash said..
It's a common misunderstanding: the idea that a worn canopy is to blame for reduced power and flapping leach. Yep, those symptoms are spot on, but it's not the canopy stretching first. The frames take the hit initially, causing the tips to stretch. So, when you see that flapping edge and feel the power dip, it's likely the frames giving in.

Another biggie we've noticed is the lack of consistent loading in the cloth. Ever checked out how the material around the windows gets all saggy and misshapen? That's your proof right there. Using fancy frames and lightweight kite cloth might buy you some time, but it's not a long-term fix.

Only a handful of brands are tackling this head-on, and it might take the industry a bit to catch up. If you're rocking high-tech leading edges, consider laminates with taffeta for durability in the critical areas. As the load eases up, you can switch to regular kite cloth.

Exciting times ahead, let's see where this journey takes us next!



Hi,I've drawn some conclusions regarding the factors that contribute to wing bagging:

1. The materials used in the canopy, particularly in the trailing edge area, are not sufficiently stiff (inelastic), despite significant improvements. I believe this is the primary factor, especially after 50-75+ sessions. It's likely that wing brands will innovate in this area, possibly using Dyneema or other materials to enhance this part of the wing.

2. Over-sheeting while sailing.Impact from waves and wipeouts.

In my opinion, features like stiff leading edges or Aluula frames, although they improve wing power, sailing capabilities, etc, they don't significantly mitigate the bagging out effect.

We need to devise a method to repair or refurbish a used wing after 75-100 sessions without replacing the canopy.

My proposal to refurbish a "long used" wing is sewing a few lines parallel to the battens to stretch the area and restore proper tension to the trailing edge.

What are your thoughts on this?




You're on the right track, but let's clear things up a bit.

As I mentioned earlier, what you're seeing with a weaker leach is just the effect, not the root cause. Some V1 wings tried fixing this with leach lines, but they ended up causing more trouble than they solved with a hooking leach.

I've experimented with replacing canopy material before, and while it's a cheaper fix than buying a whole new wing, once the frame is stretched, it's game over.

Regarding your idea about leach take-ups, they don't quite cut it. We've actually found that full battens can extend sail life better. Unfortunately, they wont let you transport them easily.

As for those fancy leading edges, they do last a bit longer than Dacron. Aluula is too brittle to handle the pressure needed in the leading edge. Dyneema, on the other hand, holds up better over time.

It's surprising that some brands haven't jumped on the full Dyneema or composite wing bandwagon yet, but who knows, maybe they're just around the corner.

Gorgo
VIC, 4979 posts
8 Apr 2024 11:26AM
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It was me who measured two identical wings on the canopy and the leading edge. I measured along the seams and across the diagonal on each panel. On the leading edge I did mid-panel measurements looking for ballooning.

I found zero measurable difference between the two, except for the tips of the bagged out wing sat 50mm closer to the strut. Moving the tip out removed all visible signs of bagging. I used the seams and corners of the panels as datum points. There could be 1-2mm error on each measurement.

Measuring well used fabric is more art than science. The leading edge is under tension, but it's also an odd shape so wrapping a tape measure around can be a little imprecise. The canopy can be held flat with weights but there's still wrinkles and variations in tension to deal with. I opted for "being reasonably careful" when measuring and trying varying amounts of pressure on the canopy to hold it flat.

I can offer no verifiable reason why the tips sit further in on the old wing. I *guess* that the coatings of the dacron degrade and that means the inflated structure is less rigid. I have no way of verifying that. I don't think that the fabrics have stretched because I can't verify that by measurement. It could be different on different wings, materials, layouts, whatever.

The symptoms of my bagged out wing is a cupped trailing edge, and the centre of effort moves back, particularly when underpowered.

I tried putting in darts by folding and taping, both straight darts and diagonals. They both resulted in a badly misshapen canopy.

I have tried a variety of numbers and lengths of battens in the trailing edge. They give a perfectly smooth trailing edge, but diagonal wrinkles appear, going from the inner batten to the strut, and a big flat luffing spot in the middle of the canopy.

Reducing the length and number of battens can move the wrinkle until it almost disappears but then the batten is not really doing anything useful. I am toying with trying some soft EVA battens to see if I can get rid of the cupping without making a wrinkle.

I am a little suspicious of the suggestion to replace the canopy. How do you know what shape to make the new canopy unless you have a brand new wing to make a template from? It's hard enough to cut panels accurately when you're making stuff from scratch and sewing and all the rest. Even doing repairs takes a bit of creativity in getting things flat after a foil has gone through a wing.

I have a North Mode Pro with 70 hours on it. It still looks brand new. Apparently the super stiff frame, canopy material and panel layout makes a difference.

My old wing has 250 hours on it. It was the first wing I bought in 2020. I still use it all the time. I haven't sucked all the flavour out of it yet. When it is powered up the bagging makes zero difference. It's only when the wind gets very light that the centre of effort tries to move back past the rear handle.

The positive of the old wing is that it is super light at 2.2kg for a 5m. It's effortless to wave it around on a wave. The flex in the frame and canopy gives it a massive top end. It is fantastic in super gusty conditions. It is very liberating to have a wing that I don't really care how destroyed it's going to get in gnarly conditions.

I destroyed it once in a solid shore break. I bought a replacement then tackled repairing and upgrading the old wing. That's how I ended up with two identical wings. It was surprisingly easy to repair (repaired strut crossways and lengthways splitting, welded exploded bladder, new handles). I am not a professional repairer. I have been doing DIY repairs on kites, paragliders and now wings over the past 30 years (and harnesses and bags and whatever).

colas
5054 posts
8 Apr 2024 1:20PM
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Like Gorgo, I would guess that the stiffness is mostly in the struts, and the current Dacron used is good enough, especially since the technique is still evolving, and you may want to change your wing anyways after some years to benefit of the shape & material advances.

Just like it would have been a bit of waste to have a super-expensive foil board made 3 years ago.

I guess most brands think that the benefit/ratio ratio of a full aramid canopy is not worth it yet.

eppo
WA, 9496 posts
8 Apr 2024 1:28PM
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Select to expand quote
King Crash said..
It's a common misunderstanding: the idea that a worn canopy is to blame for reduced power and flapping leach. Yep, those symptoms are spot on, but it's not the canopy stretching first. The frames take the hit initially, causing the tips to stretch. So, when you see that flapping edge and feel the power dip, it's likely the frames giving in.

Another biggie we've noticed is the lack of consistent loading in the cloth. Ever checked out how the material around the windows gets all saggy and misshapen? That's your proof right there. Using fancy frames and lightweight kite cloth might buy you some time, but it's not a long-term fix.

Only a handful of brands are tackling this head-on, and it might take the industry a bit to catch up. If you're rocking high-tech leading edges, consider laminates with taffeta for durability in the critical areas. As the load eases up, you can switch to regular kite cloth.

Exciting times ahead, let's see where this journey takes us next!


Well the new Armstrong Xps have the wing tips pre tensioned - that then move out under pressure creating a pretty stiff canopy. As far as longevity - we will see.

King Crash
NSW, 306 posts
8 Apr 2024 4:37PM
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Doing a cut-out-patch panel replacement is pretty straightforward. You can tweak the seams later if needed, but if you're pairing an exotic canopy with a Dacron frame, it's like putting lipstick on a pig. There are better ways to spend your money.

Adding a leach line with adjustable tension depending on wind speeds could be a game-changer. If your leach is hooked, it might be time to fair those seams. The Armstrong V1 wings had some solid leach lines that kept them going strong for ages.

Another option is to create a frame template from a newer wing, craft your own frame, and choose any canopy you fancy. Dimension Polyant offers Tylaply, a carbon laminate-free cloth that's built to last, c.$110/m

BWalnut
365 posts
8 Apr 2024 2:43PM
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Select to expand quote
Gorgo said..
It was me who measured two identical wings on the canopy and the leading edge. I measured along the seams and across the diagonal on each panel. On the leading edge I did mid-panel measurements looking for ballooning.

I found zero measurable difference between the two, except for the tips of the bagged out wing sat 50mm closer to the strut. Moving the tip out removed all visible signs of bagging. I used the seams and corners of the panels as datum points. There could be 1-2mm error on each measurement.

Measuring well used fabric is more art than science. The leading edge is under tension, but it's also an odd shape so wrapping a tape measure around can be a little imprecise. The canopy can be held flat with weights but there's still wrinkles and variations in tension to deal with. I opted for "being reasonably careful" when measuring and trying varying amounts of pressure on the canopy to hold it flat.

I can offer no verifiable reason why the tips sit further in on the old wing. I *guess* that the coatings of the dacron degrade and that means the inflated structure is less rigid. I have no way of verifying that. I don't think that the fabrics have stretched because I can't verify that by measurement. It could be different on different wings, materials, layouts, whatever.

The symptoms of my bagged out wing is a cupped trailing edge, and the centre of effort moves back, particularly when underpowered.

I tried putting in darts by folding and taping, both straight darts and diagonals. They both resulted in a badly misshapen canopy.

I have tried a variety of numbers and lengths of battens in the trailing edge. They give a perfectly smooth trailing edge, but diagonal wrinkles appear, going from the inner batten to the strut, and a big flat luffing spot in the middle of the canopy.

Reducing the length and number of battens can move the wrinkle until it almost disappears but then the batten is not really doing anything useful. I am toying with trying some soft EVA battens to see if I can get rid of the cupping without making a wrinkle.

I am a little suspicious of the suggestion to replace the canopy. How do you know what shape to make the new canopy unless you have a brand new wing to make a template from? It's hard enough to cut panels accurately when you're making stuff from scratch and sewing and all the rest. Even doing repairs takes a bit of creativity in getting things flat after a foil has gone through a wing.

I have a North Mode Pro with 70 hours on it. It still looks brand new. Apparently the super stiff frame, canopy material and panel layout makes a difference.

My old wing has 250 hours on it. It was the first wing I bought in 2020. I still use it all the time. I haven't sucked all the flavour out of it yet. When it is powered up the bagging makes zero difference. It's only when the wind gets very light that the centre of effort tries to move back past the rear handle.

The positive of the old wing is that it is super light at 2.2kg for a 5m. It's effortless to wave it around on a wave. The flex in the frame and canopy gives it a massive top end. It is fantastic in super gusty conditions. It is very liberating to have a wing that I don't really care how destroyed it's going to get in gnarly conditions.

I destroyed it once in a solid shore break. I bought a replacement then tackled repairing and upgrading the old wing. That's how I ended up with two identical wings. It was surprisingly easy to repair (repaired strut crossways and lengthways splitting, welded exploded bladder, new handles). I am not a professional repairer. I have been doing DIY repairs on kites, paragliders and now wings over the past 30 years (and harnesses and bags and whatever).


Great info and I want to point out that tracking hours (I track miles) or something tangible like you have is important to these discussions. When people say they bought a quiver that is now two years old that doesn't mean much to me. Two years for me is 300 sessions at 2-3 hours a session. Two years for someone else might mean 40 sessions.



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"Bagging out caused by le/tips stretching, not canopy?" started by foilfondler