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 Post subject: Re: Switch Labs
PostPosted: Mon Apr 07, 2014 7:18 am 
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Location: drtuba.eu, kite-stuff.org, eXtremist.si, kajtar.si
Hi,

video does not work (it was working few days ago...). It was good that you showed positives and negatives of the constructions. By doing as you do you get probably the bomb proof seam. From what I read that was your goal? On the other hand you're adding approx. 200g additional weight on mid-sized kite. The bad was that you stated industry standard from several years ago... only one or two brands is still using this kind of construction (say "unprotected"...).

From reparation perspective - the reality is that only few brands had the problems with LE closing seam. North had probably the most on older models - using lighter dacron, which was slowly eaten by the thread.

As GregK wrote these webbing solutions only adds to the costs of the repair, there are more clean solutions (which are strong enough).

From designer point of view here are the reasons why LE seam is failing IMO:

- bad quality dacron
- bad labour sewing, by making uneven, too loose stitching
- too much stress between the panel joints (too sharp angle between panels - too little panels), bad for the seam

IMO you could go with "industry standard" plus just additional reinforcement over the seam (double LE closing seam stitch), also because you're using curved LE (read even stress on the seam).

The thing is that kite will fail at the (next) weakest point. Normally that is just behind/near reinforcement... having to big jump in reinforcement weights is also not good. Also think of car's breaking zones... predict...

:idea: overpressure valves...?

M2C
:bye:





switchkites wrote:
Greg:
Seam vs fabric strength is indeed an important consideration. We have ongoing dacron, canopy fabric and associated seam tests however the video production is not finished. Your patience is appreciated.

Regarding the LE closing seam failure mode, it is weighted to the flat side but our Lab tests also show failures on the folded side.

As you mention, the webbing cover adds some strength by protecting the thread but LE seam strength is more a function of dacron (or other reinforcing) layers and their relative strength. You are also correct in noting the bend radius of the construction as a factor.

Attached is a pic which shows Switch LE construction and strut connection. The Dacron doubler is on the outside of the LE closing seam.
Thanks for your interest and questions.
Your Switch Kites Team
Attachment:
Double-Dacron.jpg


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 Post subject: Re: Switch Labs
PostPosted: Mon Apr 07, 2014 10:01 am 
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Joined: Fri Jul 08, 2011 12:29 am
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Location: New Zealand
Hello Gigi:
Thank you for your comments and suggestions. We agree material quality and sewing precision are key.

The double Dacron layer on a 10sqm Nitro3 closing seam weighs 76gm over no reinforcement. The lab tests show it is much stronger. They also show no failures at the double to single dacron (next weakest.)

Our lab testing mission is to insure Switch construction is an industry leader in strength and durability.
Your Switch Kites Team


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 Post subject: Re: Switch Labs
PostPosted: Mon Apr 07, 2014 12:01 pm 
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Im still waiting for an answer by the switch lab team on the Break strength of your latest control bar...
You have shown everything else but that in the videos.
When can we expect to see something ???


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 Post subject: Re: Switch Labs
PostPosted: Mon Apr 07, 2014 2:57 pm 
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Joined: Mon Feb 17, 2014 5:55 pm
Posts: 87
@switchkites

Great job, guys. Really like what I am reading in this thread from you guys and the community using your products. Seems like in your 3rd generation of the Nitro you are starting to dial it in and as well with your second gen bar. What I like the most is your direct to customer model to keep your pricing well under the competition while also offering a money back guarantee. The website is clean and nicely laid out from a UI experience. Please stick with the direct to customer model and business.

One quick question I have as I can not seem to find this on the site about your bar: What is the bar length and/or is it adjustable? From the pictures, the bar looks pretty similar to the Core sensor bar.

Keep up the good work!


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 Post subject: Re: Switch Labs
PostPosted: Mon Apr 07, 2014 4:54 pm 
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Location: Comox, BC
GregWoj wrote:
One quick question I have as I can not seem to find this on the site about your bar: What is the bar length and/or is it adjustable?

Go to the spare parts page for the bars only - the new Controller 2 bar comes is a 44 -55 cm standard length and a Large 50 - 60 cm version.

Agree though that this very basic info should be in the write-up on the bar in its main page.


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 Post subject: Re: Switch Labs
PostPosted: Mon Apr 07, 2014 5:25 pm 
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How wide was the seam in your tensile test dog - bones ?

I just found a reference stating the tensile strength of DP 170 g/m2 Dacron at 25 kN/m ( http://enu.kz/repository/2009/AIAA-2009-2338.pdf near the end of the paper ), so if your test seam is 50 cm wide your seam strength matches the fabric strength. :D


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 Post subject: Re: Switch Labs
PostPosted: Mon Apr 07, 2014 9:40 pm 
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Hello Shave the Whales:
There are many possibilities for lab tests. We prioritize to insure Switch quality, strength and durability. Please view the Switch Lab videos on the website regarding bar testing. We tested the Switch Controller2 bars during development and production by repeatedly cycling to 180kg (400lbs.) That means an Olympic weightlifter could safely use a Switch Controller2 for repeated 400pound lifts.
Thanks for your interest.
Your Switch Kites Team


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 Post subject: Re: Switch Labs
PostPosted: Tue Apr 08, 2014 4:11 am 
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Apologies - the video was inadvertently deleted. It has been uploaded again and you can see it here:



https://www.youtube.com/watch?v=irvW8PZv6IA


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 Post subject: Re: Switch Labs
PostPosted: Tue Apr 08, 2014 6:10 am 
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Err that video is showing leading edge strength, not a bar breaking...


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 Post subject: Re: Switch Labs
PostPosted: Tue Apr 08, 2014 6:47 am 
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On the website when you go the various features of the bar, choose the actual picture of the bar and there is a vid below showing some strength tests. I know why you are asking, you are an animal!! Lol. It's a good unit this bar, well thought out, well constructed.


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