Saving the CH 1

Kitesurfing/Kiteboarding on Liquid H2O

Saving the CH 1

Postby tungsten » October 12th, 2013, 9:52 am

Don't just ditch your CH1's yet. I'm currently reverse engineering the CH2 to see what the important changes are. 3/4 of it is resolved, just a few more tests. Solution will require 2h of light sewing machine work.

Back in a week. cheers, tungsten
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Re: Saving the CH 1

Postby steuu » October 14th, 2013, 7:29 am

Great tungsten!!! :lol:
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Saving the CH 1 - WHAT'S ON THE PLATE

Postby tungsten » October 14th, 2013, 8:01 am

WHAT'S ON THE PLATE

So here are the main known flying characteristics of CH1.

On the up side, the CH1 is a fast turner, powerful kite with a huge power surge, and fast flier through the window. It is the performance kite ARCusers craved for.

On the down side, the CH1 comes with some characteristics considered undesirable by many. Especially in gusty / shifty conditions, the CH1 gets out of control at times even in the hands of seasoned ARCusers. Incidents and accidents have been reported. Those characteristics are namely:

1. Hand clap. Some CH1 tend to clap for no obvious reason and fall down in the power zone.

2. Hunting. CH1's tend to hunt around the skies with no bar input. Steering is indirect and inaccurate.

3. Bad launch / relaunch when under inflated or wet. Launch procedure requires a lot more internal pressure than previous ARCs and is a lottery - kite may rise a bit, clap, and tumble down in the power zone with nothing left to do.

With the CH2, PL took care of all those down sides. It's a brilliant, powerful, perfectly balanced kite, a wee bit dumbed down in terms of turning speed, but still plenty fast, and so reliable. Now as PL showed it's possible, I decided I will have a close look at the differences between CH1 and CH2 in order to find out what has to be done to tame the beast. If they can do it, we can do it.

And indeed, the differences between the two are rather incremental than fundamental.

- to be continued -
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Re: Saving the CH 1

Postby aatamian » October 14th, 2013, 9:59 pm

Cannot wait to see the results as I had lost hope following my recent post "How to make a CH1 safe once for all".
Good luck and keep us posted!

Avo
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Re: Saving the CH 1

Postby Mikey » October 15th, 2013, 9:53 pm

wollo,

your da man!
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Saving the CH 1 - ANALYSIS CH1 vs. CH2

Postby tungsten » October 15th, 2013, 10:58 pm

I had a closer look at the differences between my CH1 and CH2. Good job PL! You found the clue! And now we also know it!

1. Planform

The planform is pretty much the same in CH1 and CH2. The wing tips are slightly smaller in CH2.

An interesting detail in the planform:
- the TE is convex,
- the chord in the middle of the kite is quite long, compared with older ARCs, and
- the third braid is positioned towards the center of the chord.

This design is new in ARCs, seen for the first time in the Chargers, and this is what makes the kite turn faster. The kite is balanced in such a way that it pivots around a point in the middle of the kite, between the second and the third braid. Whereas, older ARCs used to pivot around the wing tip rather than the middle of the kite.

And this design is the reason for the kite hunting around the skies. The design principle is good, but it's a bit over engineered towards ease of turning. Quite simply, the balance of the CH1 is a tad too far rearward. And the fix for this is as simple: the rear strap is too short. We'll add a bit.

CH2 vs CH1-2.jpg
CH2 vs CH1-2.jpg (164.15 KiB) Viewed 18162 times



2. Internal braids

Internal braid position is pretty much the same on CH1 and CH2. At least at the bottom skin.

The braids run parallel along the bottom skin, from wing tip to wing tip. They fold over forming the line attachment points and run back into the kite, to the top skin. Those braid ends are then sewn down on the top skin.

The position where they're sewn down on the top skin is crucial. Those braid ends put tension to the top skin, making it smooth in the leading edge part of the kite. They also determine the shape and volume of the kite tips and shoulders. And, if sewn in wrongly, they are able to badly distort the wing tip.

And this is where CH1 and CH2 are different.

You see in the pic
- the yellow lines (braid on bottom skin on both CH1 and CH2),
- the black lines (braid on top skin CH1) and
- the red lines (braid on top skin CH2).

On CH2, the top skin braid runs roughly parallel to the bottom skin braid.

On CH1, the top skin braid pulls at an angle.

CH1 was the first (and last) kite where PL tried this. Nor SYN, CH2 or PH2, not to speak of the older ARCs, do show this rearward angle of the top skin braids.

CH2_CH1_vergleich.jpg
CH2_CH1_vergleich.jpg (284.12 KiB) Viewed 18162 times


The braid position on CH1 was chosen for a maximum tension of the top skin. But it caused the wing tip to be badly distorted. The picture shows the leading edge bulging forward, the shoulder wrinkled, and overall a bad looking wing tip:

CH1-Side.jpg
CH1-Side.jpg (83.11 KiB) Viewed 18162 times


PL_Charger.jpg
PL_Charger.jpg (51.16 KiB) Viewed 18162 times
Last edited by tungsten on October 17th, 2013, 6:03 pm, edited 8 times in total.
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Re: Saving the CH 1

Postby tungsten » October 15th, 2013, 11:20 pm

As opposed to a smooth looking wing tip of CH2:

CH2_4.png
CH2_4.png (207.07 KiB) Viewed 18161 times




Tl;dr: Here's the culprit:

- the braids sewn onto the top skin in the wingtip distort the tip shape and make the kite clap and launch lousy.

- the rear braid, being a bit too short in the middle cells, make the kite hunt around the skies.





- To be continued with THE FULL FIX FOR CH1.9 -
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Re: Saving the CH 1 - ANALYSIS CH1 vs. CH2

Postby steuu » October 16th, 2013, 7:13 am

This is very interesting!! :shock:
I have a CH1 12... should I buy a sew machine!??!

tungsten wrote:
On CH2, the top skin braid runs roughly parallel to the bottom skin braid.

On CH1, the top skin braid pulls at an angle.

CH1 was the first (and last) kite where PL tried this. Nor SYN, CH2 or PH2, not to speak of the older ARCs, do show this rearward angle of the top skin braids.


Is the image correct!??! I see the angle for the pink braid... the CH2 in the legend... I think the color are wrong... or am I wrong!?!? :)
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Re: Saving the CH 1

Postby tungsten » October 16th, 2013, 8:14 am

steuu, the pic is correct. the explanation maybe is not clear enough.

I refer to the general angle between the bottom skin braid (yellow) and the top skin braid (black for CH1; red for CH2). I don't refer to the kink in the second braid on the top skin.

CH2:
1. braid (LE): bottom skin braid (yellow) and top skin braid (red) run parallel.
2. braid (middle): top skin braid (red) has a first attachment point rearward, then turns to run parallel to bottom skin braid (yellow)

CH2_messen.jpg
CH2_messen.jpg (728.06 KiB) Viewed 18143 times


CH1:
1. braid (LE): bottom skin braid (yellow) and top skin braid (black) form an angle of 40 degrees.
2. braid (middle): top skin braid (black) forms an angle of 45 degrees vs. bottom skin braid (yellow) until first sewing point; then turns even further back to form an angle of 60 degrees vs. bottom skin braid (yellow).

CH1_messen2.jpg
CH1_messen2.jpg (440.38 KiB) Viewed 18143 times


The result of the fix, which I still have to write up and post here, is such that you can hardly make a difference between CH1 and CH2 in handling and flight. Flown them back to back.

I have fixed CH12 and CH15 so far. I will therefore post the full step-by-step description of the fix, good enough to do it yourself if you have experience with the sewing machine, or carry it to your sail maker / kite repair shop / chute repair shop and have it fixed according to specs.

The whole fix took me 3 hours per kite, which had correct braid measurements. If you have kites with uneven braids from the start, you have to correct those as well, which is another half hour of work.

I might even be putting my money where my mouth is and offering the fix as a service (in Europe), test flight included. It's that good. Let me know if there's interest.
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Saving the CH 1 - THE FULL FIX FOR CH1.9

Postby tungsten » October 17th, 2013, 12:15 pm

So here is the fix. Step by step.

1. Check your kite for correct braid measurements.

Measurements in the wing tips are crucial. Those are i.e. the official measurements of the CH1_15. You have to fix those first if they are different - to remind you, there has been a number of kites with faulty braids.

For different kite sizes, please folks, if you have a functioning CH1, invest those 5 minutes worth an effort and post the measurements here.

CH15braid_measure.jpg
CH15braid_measure.jpg (36.17 KiB) Viewed 18056 times
Last edited by tungsten on October 17th, 2013, 6:21 pm, edited 3 times in total.
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Saving the CH 1 - THE FULL FIX FOR CH1.9

Postby tungsten » October 17th, 2013, 12:22 pm

2. Check your kite for correct braid seams.

Stretch out the kite from attachment point to attachment point. Watch the the top and bottom skin for

this

P1020839.JPG
P1020839.JPG (165.99 KiB) Viewed 18056 times


Too much tension in the braid ripped the seam open. Braid seams have to be fixed first.
Last edited by tungsten on October 17th, 2013, 6:04 pm, edited 1 time in total.
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Saving the CH 1 - THE FULL FIX FOR CH1.9

Postby tungsten » October 17th, 2013, 12:55 pm

Now, when your kite's seams and braids are fixed and within the tolerances, we start the FIX. We will copy the braid position of the CH2 onto our CH1. We are talking about the braids sewn down on the top skin in the wing tips. We only change two braids:

- the 1st braid (LE)
- the 2nd braid (middle)

We will NOT touch the 3rd braid (TE).

The new braid positions, measured from TE to the middle of the braid:

CH1_12_new attachment points.jpg
CH1_12_new attachment points.jpg (91.27 KiB) Viewed 18039 times



3. Open the TE.

In order to change the braids, we need to access the inside of the wing tips. We'll reach in through 2 openings:

- the inflate zip
- the next cell down from the inflate zip, towards the wing tip. Therefore we need to unstitch the TE seam in the cell with CHARGER written on it.

Open TE.jpg
Open TE.jpg (56.35 KiB) Viewed 18052 times



4. Change the braid position on top skin.

Now we made our entrance to the kite, we'll start changing the braids. In the following pics of the kite already fixed, you see where the braids were sewn down, and where they're supposed to go. You see the braid through the top skin as a dark shadow.

Old seam.jpg
Old seam.jpg (70.92 KiB) Viewed 18044 times


New seam.jpg
New seam.jpg (72.38 KiB) Viewed 18039 times
Last edited by tungsten on October 17th, 2013, 6:05 pm, edited 4 times in total.
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Re: Saving the CH 1

Postby Timothy Grossnickle » October 17th, 2013, 2:12 pm

Hi Tungsten,

I can only see through your step #3 on Arcusers. Can you do another post beginning with step #4?

Thanks much,
Tim
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Saving the CH 1 - THE FULL FIX FOR CH1.9

Postby tungsten » October 17th, 2013, 3:53 pm

5. Put the braids in the new place and sew them down:

- unstitch the braid,
- close the gap with a new seam,
- unstitch the new braid position,
- bring the braid in position (between top skin and rib), and
- sew it down.

Make sure you understand how the braid was sewn in originally and copy that. The seam goes through the top skin (both layers, where they overlap), braid, and the folded over rib.

Some part of the braid is doubled up with ripstop nylon. This is to avoid stretch and distribute the load evenly on to the top skin. When you put the braid in the new place, use the same technique:

doubled up braid.jpg
doubled up braid.jpg (65.62 KiB) Viewed 18042 times



IMPORTANT: the braid is sewn in SHORTER than the top skin above. When you put the braid in the new place and fix it for sewing (with a pin), make sure you do shorten the top skin by 1.5cm, folding it over and also securing it with a pin. This is 1.5cm PER CELL. Every time you sew the braid down, the braid has to be 1.5cm shorter than the top skin.

Like this:

pin.jpg
pin.jpg (179.06 KiB) Viewed 18042 times
Last edited by tungsten on October 17th, 2013, 6:06 pm, edited 1 time in total.
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Saving the CH 1 - THE FULL FIX FOR CH1.9

Postby tungsten » October 17th, 2013, 4:59 pm

6. Quality Control and closing TE

Now that the internal braids are fixed on the top skin in the new positions, we check our job, make sure we have not sewn accidently through top and bottom skin or any other part of the kite we did not want to include in the seam, and close the TE again where we unstitched it. No pic for that.

CONGRATS. TOP SKIN BRAIDs ARE FIXED.




7. Move on to the braids on the BOTTOM SKIN.

The long ones. Here we install the old tungsten mod by shortening the second (middle) braid in the inflate zipper cell. Like this:

CH1_shorten wing tip braid.jpg
CH1_shorten wing tip braid.jpg (78.8 KiB) Viewed 18036 times
Last edited by tungsten on October 17th, 2013, 6:08 pm, edited 3 times in total.
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Saving the CH 1 - THE FULL FIX FOR CH1.9

Postby tungsten » October 17th, 2013, 5:47 pm

8. Shorten 2nd braid in middle cell

Next, we shorten the middle braid in the middle cell. This is because the original CH1 was sitting a bit deep in the window. With the modifications we are making, the kite will sit a bit more forward in the window. To avoid the kite from luffing, we add a bit more beef.

Like this:


CH1_middle cell braid.jpg
CH1_middle cell braid.jpg (98.39 KiB) Viewed 17957 times



9. Lengthen 3rd (TE) braid in middle cell

And now we make the kite fly a bit more forward by adding length to the third (TE) braid in the middle cell. We reach through the deflate zipper and grab the power adjuster on the third (TE) braid. The power adjuster buckle is sewn onto the braid.

The easy fix is to simply cut the braid between the points where the power adjuster is sewn on, melt the cut ends down a bit with a lighter, and have the power adjuster hold the load of the braid. If you have some 1" braid material lying around, can cut as above and insert some 10cm of braid. As you please.

This adjuster will help you to tune the kite's flying characteristics. I found that on CH12 and CH15, some 5-6cm more braid length feels good. You'll do your own fine tuning according to your liking.

Here's the pic:

CH1 adjuster.jpg
CH1 adjuster.jpg (78.07 KiB) Viewed 18034 times
Last edited by tungsten on October 18th, 2013, 1:04 pm, edited 3 times in total.
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Saving the CH 1 - THE FULL FIX FOR CH1.9

Postby tungsten » October 17th, 2013, 5:58 pm

10. Get rid of those VPC3 bridles.

I sound like an old broken record, but IMHO they are "not so good". PL obviously thought the same and went back to the old VPC on the CH2.

I fly the tungsten fixed bridles since the SYN, I'm very happy with those, and I stick with them throughout all of my kites.

Making your own bridles has been described umpteen times on this forum, do a quick search.



11. New spars.

This is optional, but I got rid of the original alloy spars as well because they tend to split open and break. I keep those for traveling. In normal use, I fly my kites with 16-18mm diameter bamboo rods. Cut to length, make a round knob with hot glue on either side, and you have the best spars you'll ever see. Indestructible, they are a bit heavier, which is no problem at all and gives the kite stability in super lulls where it gently falls backwards on its TE. As you please.



That's all folks. You've got a CHARGER 1.9 now. Won't see much difference to a CH2. Trim it with the power adjuster in the middle cell and enjoy.

cheers, tungsten
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Re: Saving the CH 1

Postby daves » October 18th, 2013, 5:46 pm

Nicely done T. Your mods make sense for the way I've observed the CH1 on the water. Thanks!

I have CH10, 12, 15 with the v1.5 strap and bridle mods. They are flying OK now, but I don't fully trust them offshore because of occasional collapse and re-launch problems. I'll most probably do the mods, but need to put aside a couple nights and a few growlers of local brew.

Couple questions:

1. When re-sewing the braids, do you just even out the length between outside attachment points and sew the middle? Or do I need to measure different lengths for each adjoining cell?
2. Do you turn the cell inside out for the top skin braids?
3. Do you have any advice on managing all the kite material while positioning the sewing machine for sewing so far into the kite? I have a small Nekki with plenty of power, but no fancy base or anything.

Any comments from PL/VO? Not necessarily looking for content, but have you received any feedback or support?

I'll probably have a couple more as I get closer to mod time, but once again, I thank you for all your work to help u s keep arcs on the forward edge. Really, if you are ever in the Seattle area, you have lots of local brewery credits in the bank.
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Re: Saving the CH 1

Postby tungsten » October 19th, 2013, 7:51 am

daves wrote:...need to put aside a couple nights and a few growlers of local brew.

Spoken like a man. Originally the fix started with
"0. Secure a sixpack of cold ones", but I then thought I don't need to mention it.

daves wrote:Couple questions:
1. When re-sewing the braids, do you just even out the length between outside attachment points and sew the middle? Or do I need to measure different lengths for each adjoining cell?

Fix the BOTTOM skin braids in the WING TIPS first. They are essential. When those are done, stretch the kite out and see how it looks. Braids are sewn to the skin only in some places, most of the cells are floating freely. If the rest is rather symmetric, roll with it. Tips are crucial, the rest not so much. There is supposed to be some tension on 2 seams per side, but not to an extent where the seam splits open. You'll see.


daves wrote:2. Do you turn the cell inside out for the top skin braids?

For sewing braids to top skin: Nope.
For unstitching, sewing Chikara strip onto the braid and such: as you please.


daves wrote:3. Do you have any advice on managing all the kite material while positioning the sewing machine for sewing so far into the kite? I have a small Nekki with plenty of power, but no fancy base or anything.

I have no fancy machine either. Grandmother's model. I also thought "this is going to be a PITA", but in the end it worked well. Only tip I could give: place your machine on a very low table. If you can handle the throttle like that, even on the floor, or consider turning the wheel by hand, it's only a short seam at a time. On a normal table, the kite pulls in all kinds of directions by gravity. In an ideal world, the machine is level with the surface where the kite is lying. Sailmakers do it that way. Try what works best, with 3 kites to go, invest half an hour to find the best position.


daves wrote:Any comments from PL/VO? Not necessarily looking for content, but have you received any feedback or support?

Nope. I tried time ago, but they don't seem to answer my mails.
I have huge support from the Norwegian importer though, Steinar Lundgren from "Dragekompaniet". He is a great guy and on top provides me with wings for testing every now and then. If it wasn't for him, there would be no fix.


daves wrote:I'll probably have a couple more as I get closer to mod time...

Fire away.

daves wrote:Really, if you are ever in the Seattle area, you have lots of local brewery credits in the bank.

Appreciate it! It's a stronger currency than the $$$ anyways 8-)
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Re: Saving the CH 1

Postby Timothy Grossnickle » October 20th, 2013, 10:33 pm

Hi T,

Much appreciate your great work on converting Ch1. Have a Ch1 19 I'd like to fix. Will probably have more questions when I get started. However, I'm wondering as I start if I could take the strap position measurements off a Syn 19 or Use the Ch2 15 measurements from the kite I have and adjust them proportionately to make them work for the Ch1 19 mods?

Regards,
Tim
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