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Building a state-of-the-art foil kite

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downunder
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Re: Building a state-of-the-art foil kite

Postby downunder » Wed May 08, 2019 8:51 am

sms-kite wrote:
Tue May 07, 2019 3:07 pm
kitexpert wrote:
Tue May 07, 2019 10:33 am

To say Soul is a middle-low performance kite is a bit too much when it easily beats all LEI's and all other foil kites not including race kites by its L/D. But I'm not saying everyone should buy a Soul because there are many other things than L/D which are essential in kites.

Soul is the best foil kite in general at the moment. With Soul it is possible to megaloop, jump over 28m high and have 17s hang time from the flat surface. No other kite has anything comparable. That shows mid AR foil kite concept has huge potential.
Sorry, but I am not really agreed with your point of view...

Soul beats easely a tube kite? Even if you are looking to do Kiteloop? Are you sure? Do you ever trie to make a big kiteloop in gusty wind with the Soul??? Because I do kiteloop with a TT since 12years with an hybride kite... I do it on the snow with foil kite and I really don't want to test a 10sm foilkite in 20kts in kitesurfing.
It is not because some top riders do this, this year, that it is a revolution... Top riders done megaloop with tube kite since 2002-2003... So the Soul have the same performance than a 2003 kite?

Foil kites are really not at the same level on depower and turn ability... They have good points and they have bad points like tube kites, like everything. The soul doesn't change the problems, today everybody can do a kite loop with a tube kite, it is so simple... And make a kiteloop with a foil kites needs to be on the good timing in the good wind with a good rider.

I change between tube kite and foil all over the year... I am always surprise when everybody tells me "The soul turns as a tube kite, the soul have the same depower"...I test it, nothing to compare. Or I heard "my tubekite is lighter than a foil, my tubekite have the same power..." seriousely a tube kite have 10-15% less power for the same surface and it is 800-1000gr heavier.

I understand that you love your soul, but this kite is more a freeride kite than a top performant kite. It is a well balance kite. But his L/D ratio is not incredible. It is approximatively the same than a race tube kite... But nobody have race kite to compare anymore.

I think that the freeride foil kite is the more interested kite because it's closed to the rider level and with the way that riders want to kite. But clearely, on every brand the L/D ratio decrease on the most popular foil kite. And it is not a design problems, it is because they want to go for a well balance kite, easy to run, fun and seccurity...

Best regards

Norbert
Yes.

It has been done by Olly Bridge, search for videos. How gusty, duno, ask him. We need to compare specific kite with a specific kite. Sure Soul can loop, can it loop better than Fuel? No, but than Fuel is not better in xyx comparing to Soul.

If I may, you are taking this personally, it is not great to assume that someone has this or that kite. I do not have the Soul. But know what it can and cannot do based on my testing while I did have it.

The performance is superficial to discuss if the rider is not a top performer. In other words, do not blame the tools.

On topics, as mentioned many times, while you were all discussing this in length one could spin up a web page with "how to start sewing the kite".

Looks like only I am posting the link to an old scanned PDF all this years :(

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Re: Building a state-of-the-art foil kite

Postby sms-kite » Wed May 08, 2019 10:36 pm

downunder wrote:
Wed May 08, 2019 8:51 am

Yes.

It has been done by Olly Bridge, search for videos. How gusty, duno, ask him. We need to compare specific kite with a specific kite. Sure Soul can loop, can it loop better than Fuel? No, but than Fuel is not better in xyx comparing to Soul.

If I may, you are taking this personally, it is not great to assume that someone has this or that kite. I do not have the Soul. But know what it can and cannot do based on my testing while I did have it.

The performance is superficial to discuss if the rider is not a top performer. In other words, do not blame the tools.

On topics, as mentioned many times, while you were all discussing this in length one could spin up a web page with "how to start sewing the kite".

Looks like only I am posting the link to an old scanned PDF all this years :(
Hello.

I spend so much time to help diy builder to trim to built to design since 20 years. The most is in fresh... Sorry.

But if you start to built a kite with D-ribs H-Ribs it will be so complicated that it is sure that you will have problems.
The first step of the DIY is to think by yourself...
Take the time to look how your kite is done
To test bridles triming
To start with a small and simple kite (may be for kids?).

So if you think that make a great 3D with 100 pieces of fabric is a good way to start... Honestly I am not sure.

DIY needs a specific way to think... All the informations are on the net. But you need to learn the sewing machin bases. You need the 3D design bases. Print pattern cut the fabric bridles... Etc etc... So it is impossible to do a post like this...

I am going to check what I have done in the past that you can use... But if the goal is to built a Soul or a race kite... It will be not a good way in my point of view.

Best regards

Nono

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Re: Building a state-of-the-art foil kite

Postby downunder » Thu May 09, 2019 2:47 am

Not a post,

a web page with "how to start sewing the kite".

No, not all information is on the net. The fragmented information is, but not all, not even close.

And than have a look at this and involvement in the project:

http://boardbuilders-forum.1077691.n5.nabble.com/

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Re: Building a state-of-the-art foil kite

Postby sms-kite » Thu May 09, 2019 1:27 pm

Hello,

May be some informations here:

http://www.construire-sa-voile.com/site ... ry/Accueil

http://foilivier.free.fr/fr/index.htm

But as I tell you it is in french, I hope google translate will help you...

I was working long time with all this guys to go ahead, lots of work, lot of problems to solve
A link to what I have done with my brother

http://sms-kite.pagesperso-orange.fr/pa ... -faire.htm

And my website, if you want to know what I do now
http://sms-kite.monsite-orange.fr/


So I think there is a lot of informations on the web, but as I tell you DIY is a spirit.

Hope you will find your way


Best regards

Norbert

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Re: Building a state-of-the-art foil kite

Postby kitexpert » Fri May 10, 2019 1:15 am

It is not that difficult to sew a foil kite, after you have the pieces you just start it. First you sew LE seams of upper and lower skins together (you can do it for all cells), then add a first rib (profile) to it, then next cell so that seams go inside. Possible dribs, bridle attachment points, straps, air intakes etc. should be of course added (actually all pieces should be prepared and ready before assembly starts). The most difficult is to sew LE area seam especially if wing is small or wingtip is very narrow because it has so small radius curve in a 3D object.

Biggest part of the seams are practically straight, so quite easy work. But all the time you must take care of alignment: seam allowance should remain same and skins and ribs must keep their correct position to each other. Alignment points are very useful here.

It is possible to sew cell seam and rib in one go but it is more difficult. Double seam is not a bad thing so doing them separately is a good way to do it. If two sided tape is used all together is more reasonable.

If someone wants to know how some detail of a foil kite should be done, just ask. Many things can be done in more than one way but I can tell one which works.

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Re: Building a state-of-the-art foil kite

Postby Rein de Vries » Sat Apr 11, 2020 7:56 am

A lot of interesting ideas, thanks! Thinking and reading about it I have a few open questions.

Say I am interested to make a high AR free ride free race HF foil kite such as Sonic/R1, I see Stefano uses MH91 with some mod on reflex and LE position. Do you consider that, with the knowledge of now, the best choice?

Another point is the strap tension. I can see quite some difference in the cell width around the straps icm with some tension in the straps. What would be a good DIY rule here? Apperently there is also some billow on the decks of up to 1percent cord or so.

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Re: Building a state-of-the-art foil kite

Postby kitexpert » Sat Apr 11, 2020 2:27 pm

I suggest to use moderate airfoil which don't have too much camber and which is not too thin, then your chances to get a working kite increase considerably.

IMO kites like Sonic/R1 are out of question, high AR kite requires a lot of experience and possibility for success is low. It is also much more laborous kite type than low or mid AR kite, it has much more parts and details. So best to limit to mid AR, they can offer quite high performance and also usability is much better.

Perhaps it is best to check and estimate strap tension from some good kite and use it. Cell width and its significance has to be noted. If straps are too long they don't help much but there is no harm either.

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Re: Building a state-of-the-art foil kite

Postby Schietwedder » Sat Apr 11, 2020 5:14 pm

I also started with some self made foil kites just because I find the topic very interesting, and love sewing anyway as a sailmaker.

But, it takes quite a lot of motivation, time!!!! and material before you get a good one. It is not a cheap hobby. I think you can be lucky to have a good one but here and there but till you really unterstand what you're doing its a long process which can take years, and I still havent reached anywhere near that point because its so many things and design parameters related to each other it is really hard to take lessons learned even when you finished a few kites.

I would say the most important points what I learned (sometimes the hard way with 200-300h of work for nothing) are:

-I know it is really tempting but as kite expert said, don't go too high in size, AR and low in thickness although I love race wings and have a really hard time not tempting to go for race wings

-It is kinda boring but try one concept with a high chance of succeeding and do it over and over again with small but effective changes to understand what has an impact on what property, learn from it and do it better on a very similar design (I have done all sorts of concepts without any strategy and its hard to really learn something. Rather a lot of guessing, but anyway its fun for me because I probably love the construction process more than the actual flying although it is awesome being attached to your own design and go for some kiting) I think Stefano was very consequent in his concepts and with a lot of talent and efficient time savings in construction by using his diy cutter got some great results.

-Cutting patterns and then cloth from those is probably taking 30-50% of the construction time manually. If you ever have the chance try to find a sailmaker with a Lasercutter, offer him some Beer and let him cut it!
I have done this for my latest kite and saved massive amounts of time. (50h maybe with internal straps, 3d shaping in LE and so on) Time that you rather spend on the beach wondering how bridle tuning works, or how you can imrpove your kite.

-I think D ribs/H ribs/mini ribs is great but not for the first 3-5 kites. You will make other mistakes that have a bigger impact on the end result and then these complex and labour intensive elements which in the end don't really matter and then its just hours that you spent building which were a bit unnecessary.

-Your kite will crash, drag over the ground, flip over in the air a lot if its not tuned correctly. Make sure to make it as strong as possible in the bridle attachments, choose a high quality cloth even if it is twice as expensive, its just not worth it spending 100-300h on a kite (if its a big one with lot of manual work) and then the cloth stretches or bridle points rip out/do not distribute the load properly on the rib.

-Its very hard to find valuable information about kite design on the internet. It is very easy to find technical information and reports about paraglider design though! (A lot in the German DHV magazine and in a few forums) Although a paraglider is open cell, has more cambered profiles which you can't really use for kite design you can learn a lot in therms of construction techniques and aerodynamics from them.

A lot of successful kite builders also or primarily do paragliders and they have a more open discussion culture in paragliding amongst designers.

Check out Hannes Papesh on YouTube or Spotify podcast (german) for example.

-The areas where I did not enough labour and where my first designs lacked the most is definetely: Air Entries/internal pressure/airfoil design/and bridle design.

-do a lot of sewing tests with your machine before getting started to make sure thread tension, needle size, stitch length, and so on are all set up properly.

-Your sewing machine (unless walking foot/equipped with puller) will tend to always transport the lower layer of cloth a bit more than the upper side. Especially true with slipery silicon coated ripstop. This can be solved with pulling on the lower cloth constantly, but more effectively by doing some 3-5cm of sticky tape every 20-50cm on allignment points to make a good compromise between time and weight "wasted" when glueing and precise sewing.
Then tensioning the cloth with one hand at the point where you glued on the allignment point and the other hand behind the needle (like a manual puller) will result in super precise and fast sewing, and!!! really low seam shrinkage due thread tension!

-Also recall if youre doing the double seam method:
When for example you already connected all the bottom and top skins to a big "kite shell" you already have seam shrinkage. Now when sewing in the ribs make sure that where ever possible, the ribs are the lowest layer of cloth directly located towards your sewing machine transport. It will transport the rib cloth a bit more than the already shrunk seam of bottom /top skin so you have a higher chance of allignment without being to much pulling cloth around.

Think the last steps is really fine tune sewing techniques and might me quite hard to understand when you never done it maybe I will do a video some day explaining.

excuse my long writing and bad english but maybe it will help some diy guys.

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Re: Building a state-of-the-art foil kite

Postby kitexpert » Sat Apr 11, 2020 6:06 pm

Schietwedder wrote:
Sat Apr 11, 2020 5:14 pm
I also started with some self made foil kites just because I find the topic very interesting, and love sewing anyway as a sailmaker.

But, it takes quite a lot of motivation, time!!!! and material before you get a good one. It is not a cheap hobby. I think you can be lucky to have a good one but here and there but till you really unterstand what you're doing its a long process which can take years, and I still havent reached anywhere near that point because its so many things and design parameters related to each other it is really hard to take lessons learned even when you finished a few kites.

I would say the most important points what I learned (sometimes the hard way with 200-300h of work for nothing) are:

-I know it is really tempting but as kite expert said, don't go too high in size, AR and low in thickness although I love race wings and have a really hard time not tempting to go for race wings

-It is kinda boring but try one concept with a high chance of succeeding and do it over and over again with small but effective changes to understand what has an impact on what property, learn from it and do it better on a very similar design (I have done all sorts of concepts without any strategy and its hard to really learn something. Rather a lot of guessing, but anyway its fun for me because I probably love the construction process more than the actual flying although it is awesome being attached to your own design and go for some kiting) I think Stefano was very consequent in his concepts and with a lot of talent and efficient time savings in construction by using his diy cutter got some great results.

-Cutting patterns and then cloth from those is probably taking 30-50% of the construction time manually. If you ever have the chance try to find a sailmaker with a Lasercutter, offer him some Beer and let him cut it!
I have done this for my latest kite and saved massive amounts of time. (50h maybe with internal straps, 3d shaping in LE and so on) Time that you rather spend on the beach wondering how bridle tuning works, or how you can imrpove your kite.

-I think D ribs/H ribs/mini ribs is great but not for the first 3-5 kites. You will make other mistakes that have a bigger impact on the end result and then these complex and labour intensive elements which in the end don't really matter and then its just hours that you spent building which were a bit unnecessary.

-Your kite will crash, drag over the ground, flip over in the air a lot if its not tuned correctly. Make sure to make it as strong as possible in the bridle attachments, choose a high quality cloth even if it is twice as expensive, its just not worth it spending 100-300h on a kite (if its a big one with lot of manual work) and then the cloth stretches or bridle points rip out/do not distribute the load properly on the rib.

-Its very hard to find valuable information about kite design on the internet. It is very easy to find technical information and reports about paraglider design though! (A lot in the German DHV magazine and in a few forums) Although a paraglider is open cell, has more cambered profiles which you can't really use for kite design you can learn a lot in therms of construction techniques and aerodynamics from them.

A lot of successful kite builders also or primarily do paragliders and they have a more open discussion culture in paragliding amongst designers.

Check out Hannes Papesh on YouTube or Spotify podcast (german) for example.

-The areas where I did not enough labour and where my first designs lacked the most is definetely: Air Entries/internal pressure/airfoil design/and bridle design.

-do a lot of sewing tests with your machine before getting started to make sure thread tension, needle size, stitch length, and so on are all set up properly.

-Your sewing machine (unless walking foot/equipped with puller) will tend to always transport the lower layer of cloth a bit more than the upper side. Especially true with slipery silicon coated ripstop. This can be solved with pulling on the lower cloth constantly, but more effectively by doing some 3-5cm of sticky tape every 20-50cm on allignment points to make a good compromise between time and weight "wasted" when glueing and precise sewing.
Then tensioning the cloth with one hand at the point where you glued on the allignment point and the other hand behind the needle (like a manual puller) will result in super precise and fast sewing, and!!! really low seam shrinkage due thread tension!

-Also recall if youre doing the double seam method:
When for example you already connected all the bottom and top skins to a big "kite shell" you already have seam shrinkage. Now when sewing in the ribs make sure that where ever possible, the ribs are the lowest layer of cloth directly located towards your sewing machine transport. It will transport the rib cloth a bit more than the already shrunk seam of bottom /top skin so you have a higher chance of allignment without being to much pulling cloth around.

Think the last steps is really fine tune sewing techniques and might me quite hard to understand when you never done it maybe I will do a video some day explaining.

excuse my long writing and bad english but maybe it will help some diy guys.
Very good post, I agree most if not all of it :thumb:

My general advice is to do lot of designs and to study existing kites carefully. It is no shame to copy or take guidance for some elements or details or constructions from good kites - your kite will not be same anyway. But copying 1:1 doesn't make much sense, then you'd lose the essential part of designing it by yourself and for sure it is easier buy that kite than to redo it.

It is also important to define carefully what is the idea or goal or intended use for kite under work. For example there is some interest to try to make a kite with not so many parts, not high performance but easy to use, high stability, light weight and good drift. Or it is possible to push the envelope to higher AR kites with more inner structures and less bridle drag etc. etc.. Possibilities for different kites are almost limitless.

Finally you must always be able to explain every part of your design, why is it like it is and what is the meaning or thought behind it.


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