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Author Topic: Parafoil from China.  (Read 795 times)
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pompebled
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« on: July 12, 2017, 02:52 PM »

Hi Guys,

Watching the video, by Jim Nicholls, I ordered me one of the cheap Parafoils from Weifang via Aliexpress:
https://www.aliexpress.com/store/product/Free-Shipping-Single-line-Kite-Software-Eight-Holes-Umbrella-Easy-To-Carry-And-Easy-To-Fly/405185_1690565040.html?spm=2114.12010608.0.0.kgZiYi
Jim's video:
https://youtu.be/JJ9ReiCWip8

I didn't realise that Weifang manufactures two sizes 185 x 85 cm and 175 x 75 cm, until I received the smaller of the two, with different colours, while the one in Jim's video is the larger one.

As it has a single row bridle, it bobs in the air, as can be seen in the video.
My smaller version does that too and it's a PITA when you're winding the kite down in a strong breeze.

Also, mine would not fly out of the bag, it had a strong pull to the right and flew to the ground in a wide arch.
Only after I adjusted the bridle by shortening the left lines the kite stayed up, but moving the bridle point to the left quite a lot makes it fly rather skewered though, it does't fly straight.
But, with, or without tails, it doesn't crash anymore.

Now, I want to address the bobbing by adding a second row of bridles to the triangles lower seam, if required a third row, making the bridle look more like the Jalbert parafoil (of which I made one some 40 years ago).

I also want to elongate the bridle by a factor 1,5, so the outer triangles don't get pulled in so much.

Would this work, or am I spoiling a (reasonably) well flying kite?

Opinions please.

Regards, Jan.
« Last Edit: July 13, 2017, 09:14 AM by pompebled » Logged

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sanleonkid
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« Reply #1 on: July 13, 2017, 02:04 PM »

I purchased one of these...... ONCE.... you get what you okay for.  I'll just stick with my AirAffairs and Greens.
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pompebled
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« Reply #2 on: July 13, 2017, 02:56 PM »

Lacking answers, I went along and removed the original bridle and used my sewing machine (a modified Borletti) to sew attachment points on the keels about 30 cm behind the original eyeylets.

While I was at it, I also ran the machine over the sloppy workmanship and reinforced where required.
I made new bridle lines using 22 lbs polyester, roughly 60 cm longer that the original.

I'll trim the bridle and once the kite stays up, I'll play with the tension of the second row to see if it reduces the bobbing as was my intention (and maybe get a steeper angle).

Pictures and report will follow.

Regards, Jan.
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bt
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« Reply #3 on: July 13, 2017, 10:49 PM »

"I ordered me one of the cheap Parafoils from Weifang via Aliexpress..."

There ya go....
You shouldn't have to be doing the stuff you're doing to the said kite.
However on a positive note your kite rebuilding/improvement skills will be an asset.
bt
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pompebled
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« Reply #4 on: July 14, 2017, 08:10 AM »

Being mainly a kite builder, in stead of -buyer, I have no problems with cheap kites, as long as they fly well.

If the build quality is according to the price, I'm happy to beef up the stresspoints, I have the gear and the skill.

I just wondered if there are parafoil builders on the forum with experience regarding adding a second (or third) row of lines to the bridle and it's effect on the flying attitude.

I built a three row bridles Jalbert type parafoil some 40 years ago, which flew very well for the better part of three decades, but it's showing it's age and needs a long tail on one side to keep it from pulling towards one side when the wind picks up (the wind always picks up overhere...).
I couldn't afford ripstop at that time, so I used wind tight fabric which was a bit heavier and needed a yearly bath in 'leaky tent fluid' (Harmisol) to keep it reasonable wind tight.
Needless to say this kite needs more wind that the cheap umbrella material kite from China.
It also pulls considerably more (3 mm braided Nylon line), which is starting to be an issue when you get older...

Regards, Jan.
« Last Edit: July 14, 2017, 08:40 AM by pompebled » Logged

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pompebled
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« Reply #5 on: July 16, 2017, 02:02 PM »

I took out my modified Borletti and added the loops on the keels.

I renewed the bridle with longer lines (30 lbs braided Dacron) and added a second row on the new loops.

It has rained a lot overhere the last few days, so when we had a dry spell today, I drove to my flying field to do some adjusting on the bridle.

Having laid out a hundred feet of line on a dog pin, the kite was launched with just tension on the front bridle.
The longer lines seem to work, because even though I kept them the same length, which made the kite bow a little, the kite only pulled marginally to the right, so I took it down to adjust the left side.
The kite went up again and flew better, but seen from behind I could see differences in the profile of the top of the cells, causing the right side to develop more lift due to the more pronounced curve, compared to the left side.

I went back to the car to get the camera and just started taking pictures when the entire horizon started to go grey with drizzle...

I put my kite bags back into the car and sat there for 20 minutes while the kite flew in the rain.
When the rain got heavier, the cells started to fill with water and the kite became too heavy to stay up in the light wind.

I packed up and went home seriously wet...

I never got around to testing the effect of the second bridle row.
To be continued.

Regards, Jan.
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pompebled
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« Reply #6 on: July 17, 2017, 10:55 AM »

Here are a few pictures, one made yesterday in the rain, you can see the second bridle hangs slack.

The second picture was taken this afternoon; a slight inconsistant breese was enough to experiment with how tight the rear bridle should be, in this picture it was too much as it started to knick the cells.

Both pictures also show how badly this kite is sewn together, the shape of the cells differ from left to right, causing the inbalance in flight.

I have to say that the longer bridle positively affects the flying attitude; I only had to make minor adjustments to keep the kite in the air, the attachment point of the bridle is almost dead center, just a smidge to the left.

I still need more airtime to adjust the individual lines of the bridle, not all lines have the same tension (yet).

When the wind briefly picked up this afternoon, I quickly let out 300 mtr of line and had the parafoil flying directly overhead in a thermal.
That was fun!

Regards, Jan.


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sanleonkid
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« Reply #7 on: July 17, 2017, 12:16 PM »

Jan,

Very Nice!!  Kite looks great in the sky.   Being an Accountant and not very good with a sewing machine, I have to get my kites PRE-FIXED.  Always envious of y'all that can do your own repairs and fixes.  Being a bit on the "short" side I've been paying my seamstress for years just to take up a couple inches on my pants and its a straight sew.

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Wayner
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« Reply #8 on: July 17, 2017, 04:10 PM »

Jan,

Thanks for the thread. Been watching with interest.
Bought many foils and sewn 5 myself. Always looking for ideas/help in tuning then.
Like lenghting the bridle line. Have a kite to practice on.
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pompebled
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« Reply #9 on: July 21, 2017, 03:00 PM »

I had some more flights in the last couple of days and the cells keep showing that knick, pulled in by the second bridle row, as can be seen in the second picture.

It also affects the flying attitude as it messes with the lifting properties of the cell profile.

Only when the flying angle is steep, the profile almost looks normal, but when the wind drops a bit and the kite sinks, the ugly dent is back.

When I release the tension on the second bridle row the profile is better, but the flying angle suffers.

I guess I need to add a third bridle row and see if I can smooth out the shape in flight.

Regards, Jan.
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« Reply #10 on: July 23, 2017, 11:00 AM »

Interested in if the 3rd row solves the problem.
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Oldgoat
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« Reply #11 on: Yesterday at 08:28 AM »

I too will be interested in seeing what you find out after adding the third row of bridles.  I have to tell you that in my experience once you get that knick/fold at the additional bridle points, well it's kind of all down hill from there Sad.  To add bridle points to a foil that originally had only a "front row" you almost always have to change the angle of incidence created by the original tow point.  Sometimes it's as easy as moving the tow point up on the existing keel, other times it's an adventure in trial and error.  Once in a while I get lucky but more often I end up going back to the original settings and accepting the bobbing.  Sometimes the bobbing and higher flight angle just seem to go hand in hand.  As you noted, you have a foil that will thermal.  Adding some drag via tails etc. might decrease the flight angle and dampen the bobbing.  Who knows.  I appreciate and encourage your experimenting and reporting the results.  IMO it's one of the ways we all learn.
Oh, by the way,  I think the lengthening of the bridles was a good move.  Sometimes foils like a bit more crown/curve and sometimes they like to be a little flatter.  It's easier to make adjustments with the longer bridle lines.  Anyway that's my 2 cents, and that's probably about all it's worth. Roll Eyes
 Smiley
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