One Bridle Mod - shorter version of Dynamic / Direct Mod

Avatar

Total Posts: 112

Joined 2006-05-30

PM

 

See the previous similarly-named topic for the initial development of this bridle by Wisha. I altered my 12m One with the original mod, flew it for about 4 sessions in September, and was really pleased with the performance improvements . On the down side, I had one kite crash ( during release to leash testing ) where the long pulley V-line wrapped a wingtip. I decided to try shorter V’s when converting my 9m One.

My shorter version on my 9m One flew just as well as Wisha’s longer version did on my 12m. I’ve scaled my shorter version down for my 7m One and up for my 12. After about 5 sessions on my 9m, and one 25 – 35 knot day on the 7m ( none on the 12m yet ), with lots of kite crashes after blown jumps and testing leash releases to both front lines and single front line, I haven’t had any bridle-wingtip snags. So time to let others try it.

It is very easy to do, requires only 4 pulleys, pigtails for the pulleys, and four lengths of leader line rope, like factory bridle ‘H’ line. Here’s a sketch, the new V-lines & pulleys are shown in red. Everything else is just a re-arrangement of existing factory bridle lines.

Here are some pictures of my modified 9m flying. First shot the kite and lines are in focus, but the viewing angle makes the bridle proportions hard to see.

In the second shot, you can make out the bridle, but sorry, lousy focus.

I’ll post the V-line lengths next.  If you decide to modify your One, please consider that this bridle modification has not been widely tested. To date, only 3 One riders ( Wisha, Noo Noo, and myself ) have modified One bridles and posted results.

If you modify your bridle, TEST IT IN LIGHT, STEADY WIND (  10 – 14 knots ) AT A VERY SAFE LOCATION, with tons of space, and no hard objects or spectators downwind. I’d also recommend setting up your bar ( at least temporarily ) to leash to single front line, so that you can fully depower the kite if needed.

Signature

Comox Kite Repair
http://www.comoxkiterepair.ca


Avatar

Total Posts: 112

Joined 2006-05-30

PM

 

Here’s how to make the shorter bridle mod.

Materials Needed :

4 pulleys :  Ronstan RF 13101-2 kite blocks ( http://www.ronstan.com/marine/product.asp?ProdNo=RF13101-2 ) - will cost between $5 - 10 US each.

V-lines : Several meters of Samson rope 7/64 inch diameter Amsteel Blue line ( http://www.samsonrope.com/index.cfm?ind=1&app=3&rope=192&inst=1 ). See the chart below for the total lengths needed for various kite sizes. You can use the factory bridle H line, but if it’s severely worn where it ran through the pulley on the kite, I wouldn’t use that section. Cost is from about $0.30 - $1.00 / ft.

Pulley pigtails : ~ 1 meter of double-braided Spectra or Dyneema cored & polyester sheathed 2 or 3 mm diameter. I used Marlow Excel Racing ( http://www.marlowropes.com/public/pageManager.cfm?page_id=161 ) New England Rope Spyderline ( http://www.neropes.com/product.aspx?mid=FBAE29336C3B26FE710A6F20A0FF186C&lid=3&pid=201 ) should work, or even the 7/16 Amsteel if you can’t get hold of some thin double-braid line - cost about $3.

Sources for these materials range from your local kiteshop, marine store ( especially one that supplies small boat / dinghy sailing tackle ), or online. There are good prices for this stuff online, but shipping and handling costs can be significant.

Here are the V-line lengths for all kite sizes.

Directions :
Remove kite bridle lines H, I, G, and E. Your commitment to this mod will determine your method of removing H. If you want to be able to go back to the factory bridle, then mark on H line where the two Figure-8 knots are just above the rear attachment loop and un-tie them, and pull the H line through the pulley on the kite. Untying these knots won’t be easy, but the knots on the front line end of H are tighter and there are more of them. Use an awl to “spike” the knot several times to loosen it up.  Far easier, provided you are committed, is to either cut the Riley pulley off the kite, or cut the H line at one end.

Install the G bridle line at the kite wingtip. This line will attach directly to the kook-proof leader on your steering line, just like on the Rise.

Cut the required length for a V1 line ( see the cut lengths in the table above – note that an 8-knot takes up about 4.5 cm of line ). Tie a Figure-8 knot at one end, thread a pulley onto the V-line, and tie a second 8-knot the appropriate distance from the first knot ( see the knot-knot lengths on the chart ). Connect the C and D bridle lines to either end of the V1 line with larks-head knots.  Using 15 – 18 cm of line, tie a pigtail onto the pulley. Attach the I bridle line to the pulley’s pigtail. It should look like this :

Make up a V2 line, with two additional knots spaced 3 cm apart at one end. These extra knots are for tuning the kite, more about them later. Attach the free end of I bridle line to the single-knot end of the V2 line. Install the E bridle line onto the former pulley attachment point on the kite. Larkhead the free ends of lines F and E to the innermost knot on the V2 line. It should look like this ( note - 3 adjustment knots are shown in this pic, but I doubt you will want/need this much adjustment, maybe on a 16m ? )

Attach a pigtail to the pulley on the V2 line. If using 2 mm diameter line, double it up for added strength and safety, as OR does on the Rise. Attach your front flying line to this pigtail’s knot.

Laying your kite flat, with the bridle lines extended back as in the picture of half the kite above, the wingtip bridle line ( G )  should extend 2 – 3 inches past the end of the pigtail on the V2 line.

Now do the other side. Regarding line lengths, my table of lengths shows measurements to the millimeter, but you don’t have to be that accurate, just make the knot-to-knot lengths similar on both sides of the kite, within a millimetre or two.

Test fly your kite on a mellow day and safe spot. Before you launch it, pull in your trim line 4 or 5 inches, just to be safe.  If it flys well, then grab a big board and try it out on the water. With E and F lines at the first knot, the bar loads should be light. Kite stability should be great, even with the kite sheeted out a long way – no more front stalls when heavily sheeted out. De-power should still be abundant, but a little less than the factory bridle. If you want more bar load and de-power, then move the E line out a knot or two.  If your kite doesn’t backstall with the trim line all the way out, the bar at the chicken loop, and the kite deep in the power zone, and you want more power from the kite, lengthen the V2-line by moving both F & E out to the last knot. If your kite backstalls too frequently, and your bar’s front and rear flying lines are equal in length, then shorten the V2 lines. When you’re happy with the kite set-up, cut off the excess on the V2 lines not being used, as I’ve done on my 9m.

I will post again the methods I used to scale the bridle down for 7m and up for 12 and 16.

Signature

Comox Kite Repair
http://www.comoxkiterepair.ca


Avatar

Total Posts: 112

Joined 2006-05-30

PM

 

Theoretically, bridle lines should be proportional to the square root of the ratio of kite areas. I confirmed this by measuring several bridle lines for the three sizes on Ones that I own. Results are tabulated below.

I’ve tabulated the ratios of average lengths. For a 7m versus 9m, the root of the area ratio ( theoretical value ) is 0.882, while measured ratios ranged from 0.894 to 0.884, so at maximum out by 1.3% The 12 to 9m ratios were out by less than 1 %.  Given that some left and right bridle lines were more than 1% different in length, I’d say it’s all within manufacturing tolerances.

If you are doing a 16m and want to confirm my line length estimates based on kite areas, measure your E, F, G, and I lines and compare their ratio to my 9m lengths. Theory says you should get a 16 -to- 9m ratio of 1.333.

If you mod your One, do it safely, and post your results.

Signature

Comox Kite Repair
http://www.comoxkiterepair.ca


Total Posts: 446

Joined 2006-10-24

PM

 

Big Hand to you Greg.

Huge amount of work and effort there - well done.

Signature

The only kiter in the Village


Total Posts: 54

Joined 2008-11-03

PM

 

Nice work Greg putting that table together. Would have been nice if OR gave us some numbers, but oh well.

Would like to know what the bottom of the wind range with the later released 12m Ones is like. The old battle tank (06) 12m that I have is very impressive and that weighs a tonne.

But if I can pull unhooked moves in 14 knots and not lose ground on a return tack (plus no stalling), then I’m pretty happy.

PS - If anyone tries the mod you WONT be going back to the original setup!!


Avatar

Total Posts: 112

Joined 2006-05-30

PM

 

One more note - remove the old Riley pulleys from the LE of your kite, once you are sold on the mod. Wisha has already pointed out they are a potential snag point, as well as adding unnecessary weight to an already heavy kite - but I’m constantly amazed at how much abuse these well-built kites can take.  I crash a lot when trying tricks, and have blown out the LE on my 12m Rise, but I’ve yet to blow up a One.

Long live the old battle tank !

Signature

Comox Kite Repair
http://www.comoxkiterepair.ca


Avatar

Total Posts: 112

Joined 2006-05-30

PM

 

Flying experiences with this bridle mod :

Yesterday I had my 7m out in gusty 25 - 35 knots. Kite flew great, but a couple of times on really aggressive power dives, the kite folded slightly span-wise ( wingtips coming a few feet closer together, into a deeper ‘C’ shape ) for a second or two, then the kite returned to its normal shape.  I probably didn’t have the LE pumped up firmly enough, but Wisha or Noo Noo, either of you seen this on your kites ?

The day before it was similar gusty wind, maybe 20 - 30 knots, and this time I had my 9m up. No stability problems, just too much time spent with the kite sheeted way out. Had one unusual event on a blown jump where I swung way under the kite, it front-stalled into a forward dive ( Hindenburgs ). I sheeted out and cranked the bar hard over on one side. At first it looked like the kite would invert as the wind pushed it back as it fell, but the kite turned 180, I evened the bar and it started climbing back up. At this point, the side of the kite that had been on the outside of the turn ( the slack steering line side ) started to pulsate. I think the bridle on that side was slightly snagged, although I couldn’t see a snag ) After two pulses, it returned to normal shape. Lines had a twist , but no front/rear lines crossed. Again, sound familiar ?

Signature

Comox Kite Repair
http://www.comoxkiterepair.ca


Total Posts: 446

Joined 2006-10-24

PM

 

The hindenburg thing sounds like it just simply didn’t have any tension in it. The wind tried to force it out but the kite’s shape is pulling it back. Does that sound right? Difficult to say without seeing it obviously

Yes, I’ve noticed the pulling together of the wing tips. I’m pretty sure it happened in the original set up too. Especially when looping the kite and you were half submerged (don’t ask). It seemed worse to me on the first incarnation of the bridle mod (without the centre and pulley line) which is why I’m trying this version now. That set up felt very sensitive to setup which seemed to take a little away from it so I’m hoping the extra support on the leading edge will help. As you say it’s a sign of the kite being really powered and sitting deep in the window. It’s a potential issue with all SLE / flat kites. In truth the only kite I’ve tried that seems to resist this better than most is the 2010 RISE. I’ve got to admit I’m not 100% sure if it will work as the direct rear line will always try and deform the kite. WIth the original pulley bridle this may have been compensated a little by the pulley and front bridle moving as well.

It’s done, ready to go but I just need the conditions and the opportunity now.

Signature

The only kiter in the Village


Total Posts: 446

Joined 2006-10-24

PM

 

Greg just had another thought on the distortion issue.

Wonder if it could partly be attributed to the shorter bridle. Although it is longer than the stock version I believe.

Thoughts?

Signature

The only kiter in the Village


Avatar

Total Posts: 112

Joined 2006-05-30

PM

 

Noo Noo - this is what I think :

When the kite’s wingtips fold in, the loads in the middle of kite, carried by bridle lines A,B, C, D, V1, and I are greater than the load in E and F, so the V2 line runs through V2 pulley until it’s stopped by the E & F connection.

If the V2 line was longer, the kite could fold more. With the fixed bridle ( i.e. factory ), I don’t think the kite could deform as much.

Why does it happen ? Perhaps the mid-section of the kite has stalled ( back-stall ), while the flow is still attached at the wingtips. The Rise’s vented trailing edge is Ross H’s solution to this problem. For the One, trimming the kite in a bit is the only solution I can see right now.

I’d like more time flying this bridle mod to see what happens with it under a wide variety of conditions. I’ve only seen it happen with my 7m and not my 9, although I have about twice the hours on the 9 and have flown it just as aggressively as the 7.

Hopefully we’ll get a few more folks mod’ing their kites and more experience with it. I’ll be interested in how the shorter version flies on your kite.

Signature

Comox Kite Repair
http://www.comoxkiterepair.ca


Total Posts: 446

Joined 2006-10-24

PM

 

My theory is a little simpler tbh. I actually think its the whole kite distorting.

The kite naturally wants to form a C shape (like anty sheet held in the wind) but is held by the stiffness of the leading edge which is in turn supported by the bridle. Under extreme load the centre of the kite is pulled more into the C Shape. I guess I’m saying tye load gets distributed more to the outer sevtions of the bridle. My Caution has a very short bridle and does this a fair bit.

I’m guessing but that may be partly why many kite designedrs have moved away from very flat profiles.

Anyway, yes it’s test time. Weather here has been bonkers so no opportunity at the moment. Very soon I hope

Signature

The only kiter in the Village


Total Posts: 11

Joined 2007-02-20

PM

 

Dear Greg and Wisha,


I have just finished re-bridling the 12 meter One with your bridle. It was easy to do, thansk to your very clear instructions.  I have yet to fly it…we are in the middle of a week of real autumn- weather, 25 knots and above, won’t be flying the 12 soon, but I’ll let you know how I like it, as soon as I do.

I am more than a little curious. I never liked the 12 meter very much at all. Way too slow for my liking. Anyway, this is not meant to slag off the 12 meter One…it’s just never been my kind of kite. Still, with the new bridle…I might get to like it.

I have a 7 meter One, that I haven’t rebridled yet…didn’t have the pulleys at hand. I want to see the effect on the 12 first anyway (sorry for the lack of trust: I do like the 7). It would be nice if it could be a bit snappier in the turns, like the 6 Rise, but on the other hand, it is a great jumper, with amazing range, an though meant as a backup for my 6, I use it a lot!

Anyway, thanks a lot for all your effort in creating and sharing this new bridle!!! I have often thought about changing the bridle so it would be similar to the bridle on the Rise, but have never taken the time for some serious thinking and testing: you seem to have!

I’ll let you know how I get on with it, and if I happen on any new adjustments, you’ll be the first to know!


Arjen


Avatar

Total Posts: 112

Joined 2006-05-30

PM

 

More experience today - 7m in gusty 25 - 40 knots - and last Saturday, in more steady wind, 28 - 32 knots.  Today, I didn’t have my LE pumped very firm,  around 5 - 6 psi. While riding, I could see the LE distorting between bridle attachment points in the gusts, and the wingtip-folding-in thing happens with the kite de-powered a lot and a gust hits it, pull the bar in a small amount, and the kite goes back to its flat normal shape.

On Saturday, I pumped the LE up quite hard, about 9 psi, kite flew beautifully, no wingtip folding. Had an awesome session.

It’s pretty clear to me now, at least with the 7m, the LE needs to be pumped FIRM.


Arjen - I hope you’re pleased with the 12; hopefully you have a 60 cm bar on it. The 12m with a 50 is like driving a bus. I often put a 60 cm bar on my 9m to tighten its turns. The 7m with a 50cm bar is pretty sweet.

Look forward to your comments.

Signature

Comox Kite Repair
http://www.comoxkiterepair.ca


Total Posts: 11

Joined 2007-02-20

PM

 

Hi Greg,


60 cm’s it is…it might be a while before you get any comments grin

It’s 7 meter time (on a 50)!!!


Total Posts: 446

Joined 2006-10-24

PM

 
GregKnowles - 23 November 2009 11:47 PM

More experience today - 7m in gusty 25 - 40 knots - and last Saturday, in more steady wind, 28 - 32 knots.  Today, I didn’t have my LE pumped very firm,  around 5 - 6 psi. While riding, I could see the LE distorting between bridle attachment points in the gusts, and the wingtip-folding-in thing happens with the kite de-powered a lot and a gust hits it, pull the bar in a small amount, and the kite goes back to its flat normal shape.

On Saturday, I pumped the LE up quite hard, about 9 psi, kite flew beautifully, no wingtip folding. Had an awesome session.

that’s interesting. Pull the bar in and the kite returns to its normal shape. My experience on my Caution is the opposite, you need to sheet out. That reinforces your theory Greg.

Either way…..........PUMP IT HARD!!!! gulp

Signature

The only kiter in the Village


Total Posts: 446

Joined 2006-10-24

PM

 

I’ve given this a go now. Well done Greg with the line lengths.

One thing I’ve noticed. When you pull on the bar the E bridle line (from the original pulley point to the V2 line) goes slack.
this happens when turning or powering up and is partly due to the kite deforming whenyou pull on that side.

Any thoughts Greg?

Signature

The only kiter in the Village