Contact   Imprint   Advertising   Guidelines

DIY Foil Kites

For all foil kite riders


klimm
Rare Poster
Posts: 16
Joined: Sat Dec 15, 2018 9:58 am
Kiting since: 0
Local Beach: will kite just in the winter, on skis
Style: winter ski riding on various terrain
Gear: paragliding and skiing ,
I just borrowed a kite to get a grasp of it and liked :)
Brand Affiliation: None
Has thanked: 0
Been thanked: 0

Re: DIY Foil Kites

Postby klimm » Sun Dec 16, 2018 6:54 pm

The computed PG height of curvature is only 27%
I meant that due to cutting of the central 19 cells, about 4 m, the projected length became only 5 m but the height remains and the 2 parts to be merged, will want to keep their shape. I did this by horizontally translating one part to another.
What I absolutelly don't know is the AoA used in kiting, and the way the designers play with AoA to modulate power.
Is there a place(thread maybe) to learn details about SP? I learned some things already by trial but some details are not clear to me

klimm
Rare Poster
Posts: 16
Joined: Sat Dec 15, 2018 9:58 am
Kiting since: 0
Local Beach: will kite just in the winter, on skis
Style: winter ski riding on various terrain
Gear: paragliding and skiing ,
I just borrowed a kite to get a grasp of it and liked :)
Brand Affiliation: None
Has thanked: 0
Been thanked: 0

Re: DIY Foil Kites

Postby klimm » Sun Dec 16, 2018 6:56 pm

kitexpert, thank you for this online course.
This parametric program, the SP is really great
Last edited by klimm on Tue Dec 18, 2018 7:10 pm, edited 1 time in total.

kitexpert
Very Frequent Poster
Posts: 619
Joined: Sun Aug 09, 2015 11:20 pm
Kiting since: 2003
Gear: many kites, also diy
Brand Affiliation: None
Has thanked: 0
Been thanked: 1 time

Re: DIY Foil Kites

Postby kitexpert » Mon Dec 17, 2018 6:21 pm

No problem :wink:
klimm wrote: I meant that due to cutting of the central 19 cells, about 4 m, the projected length became only 5 m but the height remains and the 2 parts to be merged, will want to keep their shape.
But these sections you are going to use have only a small part of the curvature of original wing. So height doesn't remain. If you join parts (18,5 cells) smoothly, keeping their shape, there will be even less curvature than what my plan suggest. But like I wrote earlier it is not that precise for curvature because foil kite structure is soft and able to adapt to different shape. Just don't go too far from the original shape it will be ok.

Don't bother 5m projected length. Let it become what it becomes when you have decided how much canopy curve you want.
klimm wrote: What I absolutelly don't know is the AoA used in kiting, and the way the designers play with AoA to modulate power.
Nowadays kites are depowerable, it means AoA changes with the bar movement. At low end AoA is limited by stability and/or L/D, high end is reached when kite backstalls. There is also "sewn in" AoA, but in your case that doesn't matter because parts are done already. But you must cut/sew mid-cell seam correctly: if you make that cell wedging you will produce (in a crude way) some AoA in kite itself which may not be a good thing.

When bridle is finished you can change/limit AoA by altering line lengths of different line rows and/or front line/back line lengths. There is also a possibility to adjust camber of airfoil. You don't need to worry that now because you will have to make adjustments anyway.

You must also estimate what kind of airfoil Vulcan has and use something like it in your model. This is not very critical though, some usual airfoil with 18% thickness at 24% and 2-3% of camber will do.

klimm wrote:Is there a place(thread maybe) to learn details about SP?
There was some basic info in some website, I don't know if it is still there.

klimm
Rare Poster
Posts: 16
Joined: Sat Dec 15, 2018 9:58 am
Kiting since: 0
Local Beach: will kite just in the winter, on skis
Style: winter ski riding on various terrain
Gear: paragliding and skiing ,
I just borrowed a kite to get a grasp of it and liked :)
Brand Affiliation: None
Has thanked: 0
Been thanked: 0

Re: DIY Foil Kites

Postby klimm » Tue Dec 18, 2018 7:16 pm

But these sections you are going to use have only a small part of the curvature of original wing.
You're right, and the foils are set radial.
I stopped playing wit=h SP an took the pluge! I cut the PG and sew it with no problems, 37 cells.Took some 3 hours so far. I do hope tomorrow to have two hours of nice weather to get the result outside (I kept the lines on it ) in order to see the shape and determine some parameters for input into SP

kitexpert
Very Frequent Poster
Posts: 619
Joined: Sun Aug 09, 2015 11:20 pm
Kiting since: 2003
Gear: many kites, also diy
Brand Affiliation: None
Has thanked: 0
Been thanked: 1 time

Re: DIY Foil Kites

Postby kitexpert » Tue Dec 18, 2018 7:47 pm

klimm wrote:I cut the PG and sew it with no problems, 37 cells.
Well done :thumb: And seam allowances are inside the cell now?
klimm wrote: (I kept the lines on it ) in order to see the shape and determine some parameters for input into SP
:?: I don't think keeping lines attached helps at all. Just try to design new canopy curve which does not deviate too much from the original shape of the parts. It will be fine.

You must measure line row locations by the chord (in %) and then decide which ones of them you will have bridle lines. A and Z (brakes) are of course mandatory.

klimm
Rare Poster
Posts: 16
Joined: Sat Dec 15, 2018 9:58 am
Kiting since: 0
Local Beach: will kite just in the winter, on skis
Style: winter ski riding on various terrain
Gear: paragliding and skiing ,
I just borrowed a kite to get a grasp of it and liked :)
Brand Affiliation: None
Has thanked: 0
Been thanked: 0

Re: DIY Foil Kites

Postby klimm » Tue Dec 18, 2018 8:10 pm

Seam allowances are inside the cells of course. On the outside I also did an extra sew, afterwards, I packed the whole in the inside out of the kite, with about 6 needles as marks, sewed and pulled the kite out from that salami :)
Indeed the As are not at 0 but few centimeters inside , like about 12-15 cm from the nose . I saw that SP requests for percents.
I kept the lines because, with some adjustments of the lines. I might be able to take a front picture, another from beneath in order to have some realistic dimensions for the SP, and a better Idea of the shape.
I don't know where the tow points will result. I wish to keep most of anchor points because this way I have a good chance to keep the canopy shape reasonable.
At level B(about 25% chord) I have a width of the foil(profile) of 41 cm, total chord is 245cm so , about 17 % .
I need to decide about the depower system too. Here the SP won't help much, I see I can't decide much about the way the lines are cascading .

kitexpert
Very Frequent Poster
Posts: 619
Joined: Sun Aug 09, 2015 11:20 pm
Kiting since: 2003
Gear: many kites, also diy
Brand Affiliation: None
Has thanked: 0
Been thanked: 1 time

Re: DIY Foil Kites

Postby kitexpert » Tue Dec 18, 2018 9:41 pm

klimm wrote:
Tue Dec 18, 2018 8:10 pm
Seam allowances are inside the cells of course. On the outside I also did an extra sew, afterwards, I packed the whole in the inside out of the kite, with about 6 needles as marks, sewed and pulled the kite out from that salami :)
Just right :thumb:
klimm wrote:
Tue Dec 18, 2018 8:10 pm
Indeed the As are not at 0 but few centimeters inside , like about 12-15 cm from the nose .
Measure that from the center, then calculate % of the chord. Other line rows as well.
klimm wrote:
Tue Dec 18, 2018 8:10 pm
I kept the lines because, with some adjustments of the lines. I might be able to take a front picture, another from beneath in order to have some realistic dimensions for the SP, and a better Idea of the shape.
Ok, but I don't think that will help. Just make a model from it and trust it. You must find out what is 2-D shape of the kite (plan view) (actually you see that from Ozone line plan picture well enough) and then make a model and decide how much canopy curve your kite will have. Use profile alignment adjustment (tip/center), input cell count, wing span, center chord, tip chord (% of center), kite shape (elliptic, 0% square, some front curvature not much if any rear curvature) and rib spacing (propositional to chord degree %). You probably have to adjust kite shape manually to get wingtips correctly shaped because they are so narrow. That option is on same window.
klimm wrote:
Tue Dec 18, 2018 8:10 pm
I don't know where the tow points will result.
Don't worry about that, use default value. You must adjust tow point/AoA anyway, this is done with some adjustment lines with knots. Your kite will fly with default value, but it may collapse etc.

klimm wrote:
Tue Dec 18, 2018 8:10 pm
I wish to keep most of anchor points because this way I have a good chance to keep the canopy shape reasonable.
That is ok, but you must cascade them chordwise, at least if you want to try some depower (mixer/speed system) in it. It will become extremely complicated if that many line rows is tried to be constructed to each having their own pulling ratio.
klimm wrote:
Tue Dec 18, 2018 8:10 pm
At level B(about 25% chord) I have a width of the foil(profile) of 41 cm, total chord is 245cm so , about 17 % .
Sounds correct.
klimm wrote:
Tue Dec 18, 2018 8:10 pm
I need to decide about the depower system too. Here the SP won't help much, I see I can't decide much about the way the lines are cascading .
Yes. Spanwise cascades are solved, do it like my plan suggest (it is also quite close to original bridle). Chordwise there is many options, both for mixers and how line rows cascade. I suggest to use normal two-pulley mixer (1:2:4 pulley ratios). One possibility could be:

A: fixed
B: (first level already cascaded together) 1:4
C and D (cascaded together) 1:2
Z (brakes) 1:1 (pulled straight)

Then you must decide where possible cascades occur. Closer to the wing the simpler upper levels will be.

On more thing. Because it is a PG wingtip bridle is different to what it is usually in kites. One method to solve it is to cascade first level (A-B-C)together, then second level is a long single line which goes to C from mixer and is pulled 1:2. Brake will be normally at the TE wingtip.

klimm
Rare Poster
Posts: 16
Joined: Sat Dec 15, 2018 9:58 am
Kiting since: 0
Local Beach: will kite just in the winter, on skis
Style: winter ski riding on various terrain
Gear: paragliding and skiing ,
I just borrowed a kite to get a grasp of it and liked :)
Brand Affiliation: None
Has thanked: 0
Been thanked: 0

Re: DIY Foil Kites

Postby klimm » Wed Dec 19, 2018 12:20 pm

Captură ecran (31).png
This would be the spanwise cascade except the 1 at the tip, because the program insist to pair this with the next(5)
I made the width of the panels proportional to chord which is a good approximation of the real canopy
I set the anchor points according to the last (in the center) profile chord measurements. It looks the others would be proportional
I think about having an extra line for the tips in order to be able to make ears as in PG :) cam cleats, rings, larkshead knots, comes to mind.
Chord wise, as the firs level of lines are already in place, I would cascade:

A: fixed
B and C cascaded together as they are very close to another. Pulley as per speed system of the PG and trimmed if needed
D ( E only if needed) cascaded together,
Z comes at 5cm from TE all over.

I will carefully analyze the other advices and come back when novelties happen :)

kitexpert
Very Frequent Poster
Posts: 619
Joined: Sun Aug 09, 2015 11:20 pm
Kiting since: 2003
Gear: many kites, also diy
Brand Affiliation: None
Has thanked: 0
Been thanked: 1 time

Re: DIY Foil Kites

Postby kitexpert » Wed Dec 19, 2018 2:57 pm

That is a good start, many things are correct.
klimm wrote: I made the width of the panels proportional to chord which is a good approximation of the real canopy
Ok, and you can adjust also the level of proportional. If it 100% all cells have similar width/length ratio, if 0% spacing is equal (cell width is constant).
klimm wrote: This would be the spanwise cascade except the 1 at the tip, because the program insist to pair this with the next(5)
You can avoid that by inserting 1 on every level of cascades first. But because it is a PG there will be some manual work to get wingtip bridle finished, but you can do it.
klimm wrote: I set the anchor points according to the last (in the center) profile chord measurements. It looks the others would be proportional
Right. Yes, usually they are.
klimm wrote:Chord wise, as the firs level of lines are already in place
You mean you would use original Vulcan bridle lines for the first level?
klimm wrote: A: fixed
B and C cascaded together as they are very close to another. Pulley as per speed system of the PG and trimmed if needed
D ( E only if needed) cascaded together,
Z comes at 5cm from TE all over.
Sounds reasonable.

I don't see clearly from your design how well 2-D shape of it matches modified Vulcan shape. Check that and adjust profile alignment if needed. You may have too much curvature in LE and too little in TE. You can also adjust wingtips wider and then manually adjust 3-4 first cells to match Vulcan, this may help to get 2-D shape more precise.

klimm
Rare Poster
Posts: 16
Joined: Sat Dec 15, 2018 9:58 am
Kiting since: 0
Local Beach: will kite just in the winter, on skis
Style: winter ski riding on various terrain
Gear: paragliding and skiing ,
I just borrowed a kite to get a grasp of it and liked :)
Brand Affiliation: None
Has thanked: 0
Been thanked: 0

Re: DIY Foil Kites

Postby klimm » Wed Dec 19, 2018 3:51 pm

Laid flat, the LE is very curved at the ends. The TE is much flatter. The picture in the lines plan, that you also have is not accurate and is laid flat anyway.
I compared my design with the real thing laid on the floor. In the design, I tried with some approximation to get as close as possible to the projected shape.
Too bad we had no wind today for a photo from beneath for comparison, and I came to a halt.
Concerning the lines, I think that only the first level could be used (about 50-60 cm) at all levels. A,B,C even some of those on the commands(brakes) Wanted to reformulate I think , but have forgotten :)
Of course I will try to use old lines where it will be appropriate, with a larks head at an end for adjustments.
The project is not finished of course, I still have some doubts with too short 2nd and 3rd level lines not to distort too much the canopy
Attachments
Captură ecran (32).png


Return to “Foil Kites”

Who is online

Users browsing this forum: No registered users and 2 guests

cron