Has anyone adjusted the line length on their setup? If so, which lines and by how much?
I have a 10M Ozone Frenzy and sometimes wish the kite were a little more aggressive with the bar fully pulled in. Does shortening the leading edge lines make the kite more responsive? Is it easy to undo the knot/etc if you don't like the modification?
Comments/discussion would be appreciated. Thanks!!
Mark
Adjusting control line length
Moderator: MK
-
markdbliss
- Posts: 30
- Joined: Thu Aug 19, 2010 10:31 am
- Location: Eden Prairie, MN
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Re: Adjusting control line length
how is the learning going? you can give me a call at 612-386-5166 and i might be able to help out.
doug
doug
Re: Adjusting control line length
I would have someone who is used to flying foils take a look at the kite. I don't know anyone who has modified their Ozone foil lines. Try pulling your depower strap (shortens the lead lines) and see how the kite responds.
Check your line lengths. I think Ozones should have all equal lengths (not sure about the 2007 Frenzy though).
Most riders here would be more than willing to take your kite for a test ride.
Check your line lengths. I think Ozones should have all equal lengths (not sure about the 2007 Frenzy though).
Most riders here would be more than willing to take your kite for a test ride.
Re: Adjusting control line length
GENERALLY SPEAKING, shorter front lines will de-power the kite, add slack to the steering lines, and make the kite less responsive. You can get the same effect by pulling the sheeting strap. You can play with line length by adjusting the sheeting strap until it flies right, note how much length you shortened or lengthened the strap. If it is shorter, you can add the equivalent amount to the back lines and get the same result as making the front lines shorter. Pig tails can also be utilized
to add length where desired on your bridle. If your kite stalls or flies backward with bar pulled in, the steering lines are too short, since you want to keep some depower available regardless. Winter is a great time to experiment with your gear until it is tuned just right.
to add length where desired on your bridle. If your kite stalls or flies backward with bar pulled in, the steering lines are too short, since you want to keep some depower available regardless. Winter is a great time to experiment with your gear until it is tuned just right.
WARNING:
I AM AN UNREFORMED SERIAL FLIRT!!
(please respond accordingly ;^{})
I AM AN UNREFORMED SERIAL FLIRT!!
(please respond accordingly ;^{})
Re: Adjusting control line length
As I understand depower kites, you really never change anything by shortening or lengthening the front lines other than where the bar throw is in relation to the sheeting angle. And all sails have only 1 sweet spot or perfect sheeting angle given an angle of wind. If you have any sail boat experience with telltales, you would easily recognize that the air flow over the leeward (top of kite) and windward (bottom of kite) side of the sail must be steady for maximum power and efficiency to be attained. And this typically occurs at a very specific angle to the wind.
On some unforgiving open cell foil kites, you will recognize that ideal sheating angle (where the bar should be for max power) is when the kite is full of air and pulling hard. But sheet in too much or too little, and the kite will deflate and loose power. When the kite is deflating even though it is still pulling (but less than when full of air), then the kite is sheeted in too much and there is turbulent air over the top of the kite. When the kite is deflating and not pulling, then the kite is most likely sheeted out too much and there is turbulent air on the bottom (and possibly top) of the kite. You can actually get some sheeting angle change and reduction/increase of power with steady airflow over both sides, but this is a typically only a few cm of bar throw in winds that are within the wind range of a given kite. This is your actual "depower" range, anything else is over sheeting or under sheeting but often feels like you are "depowering" when you are actually stalling one side of the kite. Both over sheeting and under sheeting will normally kill some of the power of the kite. This is how foil kites get away with launching hot (directly down wind) in such high winds by sheeting in/pulling the bar when the kite is below 45degrees in the wind window, though I do not recommend it. But I still nearly always launch that way. Some tube kiters making the change from inflatables to foils think that the bar on a foil kite works the opposite way that their water kites work. This is mostly due to inflatable kiters flying their kites so high and not accessing the back of the wind window without tons of speed (kite looping) in the kite. But the principal is exactly the same on an inflatable as an open cell foil, though an open cell foil kites shape and dead-downwind power can be almost completely destroyed by over sheeting much more so than the ridged shape of an inflatable in the same situation.
So if that perfect sheeting angle happens to be 15cm up from completely sheeted in on the bar, you should work around that area. By keeping your bar close to this you will maximize the efficiency of the kite. If you try to shorten your front lines 8cm, the sweet spot will move toward the bottom of the bar by 8cm and be only 7cm up from the bottom of the bar throw. If you shorten your lines by 8cm again, the sweet spot will have moved below the bar and you will not have access to it within the throw of the bar.
By this example, there is no real way that you can change the max power of the kite by lengthening or shortening the center lines other than to remove the sweet spot from the bar throw. Maximum power can only be achieved at one sheeting angle for a given set of lines and bridle arrangement. The only two ways I know of to affect the kites top end performance at a given wind speed is to change the length of the line set or to change the bridle layout/length. Please do not try the latter.
So what is a trim strap for? Well I use it for two things. First, I want the sweet spot on the bar throw to be at a comfortable length for my arms to reach since I do not want to have to reach out too far while comfortably cruising. Second, and this is going to seem to go against everything I said before, I use it to depower the kite. This is because sometimes I kite way overpowered and do not really need to access anything below that sweet spot so I will adjust the sweet spot to be almost at the bottom of the bar throw. This gives me access to much more under sheeting, or what is commonly referred to as "depower". However, I loose the ability to over sheet the kite to land it. This is where the brake handle becomes a necessity.
There are other variables to consider with regards to wind speed but for a given wind speed, less my second reason to use the trim strap, the above should hold true.
Feel free to shoot me down if I have it wrong.
On some unforgiving open cell foil kites, you will recognize that ideal sheating angle (where the bar should be for max power) is when the kite is full of air and pulling hard. But sheet in too much or too little, and the kite will deflate and loose power. When the kite is deflating even though it is still pulling (but less than when full of air), then the kite is sheeted in too much and there is turbulent air over the top of the kite. When the kite is deflating and not pulling, then the kite is most likely sheeted out too much and there is turbulent air on the bottom (and possibly top) of the kite. You can actually get some sheeting angle change and reduction/increase of power with steady airflow over both sides, but this is a typically only a few cm of bar throw in winds that are within the wind range of a given kite. This is your actual "depower" range, anything else is over sheeting or under sheeting but often feels like you are "depowering" when you are actually stalling one side of the kite. Both over sheeting and under sheeting will normally kill some of the power of the kite. This is how foil kites get away with launching hot (directly down wind) in such high winds by sheeting in/pulling the bar when the kite is below 45degrees in the wind window, though I do not recommend it. But I still nearly always launch that way. Some tube kiters making the change from inflatables to foils think that the bar on a foil kite works the opposite way that their water kites work. This is mostly due to inflatable kiters flying their kites so high and not accessing the back of the wind window without tons of speed (kite looping) in the kite. But the principal is exactly the same on an inflatable as an open cell foil, though an open cell foil kites shape and dead-downwind power can be almost completely destroyed by over sheeting much more so than the ridged shape of an inflatable in the same situation.
So if that perfect sheeting angle happens to be 15cm up from completely sheeted in on the bar, you should work around that area. By keeping your bar close to this you will maximize the efficiency of the kite. If you try to shorten your front lines 8cm, the sweet spot will move toward the bottom of the bar by 8cm and be only 7cm up from the bottom of the bar throw. If you shorten your lines by 8cm again, the sweet spot will have moved below the bar and you will not have access to it within the throw of the bar.
By this example, there is no real way that you can change the max power of the kite by lengthening or shortening the center lines other than to remove the sweet spot from the bar throw. Maximum power can only be achieved at one sheeting angle for a given set of lines and bridle arrangement. The only two ways I know of to affect the kites top end performance at a given wind speed is to change the length of the line set or to change the bridle layout/length. Please do not try the latter.
So what is a trim strap for? Well I use it for two things. First, I want the sweet spot on the bar throw to be at a comfortable length for my arms to reach since I do not want to have to reach out too far while comfortably cruising. Second, and this is going to seem to go against everything I said before, I use it to depower the kite. This is because sometimes I kite way overpowered and do not really need to access anything below that sweet spot so I will adjust the sweet spot to be almost at the bottom of the bar throw. This gives me access to much more under sheeting, or what is commonly referred to as "depower". However, I loose the ability to over sheet the kite to land it. This is where the brake handle becomes a necessity.
There are other variables to consider with regards to wind speed but for a given wind speed, less my second reason to use the trim strap, the above should hold true.
Feel free to shoot me down if I have it wrong.
Re: Adjusting control line length
The age old mod for Frenzies (and Mantas) is to tie figure 8 knots on the leaders to the steering (outside) lines. You tie them between the reload loops and the flying line attachment points at the ends of the line. Shortening the outside lines increases the angle of attack powering the kite up a bit and sharpening the steering response. This is a mod folks have been doing for years and Ozone even had on their website a couple years back. I have a number of Frenzies and a Manta from 05-07' and have done this on all of them. Another Ozone kiter on this board, Mike B does this to his kites as well. The newer Ozone bars have trimmers for the outside lines so you don't have to mess with knots to shorten them. The other trick for greater turning response is to grab the outside line by hand when bar inputs aren't enough.
All that said, you'll probably only feel a 5-10% positive improvement. What you really need is a bigger kite for the light winds we typically have around here, something in the 12+ meter range.
All that said, you'll probably only feel a 5-10% positive improvement. What you really need is a bigger kite for the light winds we typically have around here, something in the 12+ meter range.
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Kiter John
- Posts: 9
- Joined: Sat Jan 02, 2010 11:53 am
Re: Adjusting control line length
There's a 10m frenzy? I thought they had 9 and 11...
I think Al's right, if you don't have enough power, move up in kite size.
I think Al's right, if you don't have enough power, move up in kite size.
Re: Adjusting control line length
06-07' Frenzies were sized 7.5,10,12&14m
I think in 05' they were 3,5,7.3,10,12&14m (before they made the Access for their smaller kite).
I think in 05' they were 3,5,7.3,10,12&14m (before they made the Access for their smaller kite).
Re: Adjusting control line length
Al C,
You are absolutely right about just needing a bigger kite. I kind of missed that point.
But shortening the leader lines (and thus the steering or brake lines) is EXACTLY the same as lengthening the center lines. It will simply move the sweet spot on the bar throw further up. There is no change in the shape or maximum power of the kite with this modification. Back line or front line length adjustment only affects the sheeting angle accessible in the bar throw.
Windsurfers would know exactly why this is the case because a windsurfing sail has an adjustment that a kite does not. Windsurfing sails depower the same way as a kite, you sheet them in and you sheet them out by adjusting their angle of attack to the wind. But no kite that I am aware of has an "outhaul" like a windsurfing sail. The outhaul is the line that pulls on the clew (back end of the sail) and shapes it either flatter like a board or fuller like a wing. There is no "flatter or fuller" adjustment on a kite, only sheeting in or out via the bar or line length adjustment. You could argue that a kite gets flatter when there is less wind/power in it, but this is not valid because a windsurfing sail or any sail for that matter will do the same at a single outhaul length. A kite is always out hauled to ONE shape when full of air on an open cell foil, closed cell foil, or inflatable. Line length adjustment or bar throw does not affect this.
The only exception to this may be with older single pulley foils like the Apex II. With a single pulley on a foil, you do get some curve change to the kite because you are bending the kite near the center when sheeting it in. But I don not believe that this property was ever exploited by designers to produce a positive performance effect that allowed you to change the shape of the foil for more power. At least I never experienced it. Double pulley foil kites (4 pulleys per kite) have somewhat eliminated this tendency of the kite to bend. This has given us foil kites with less bar pressure and more ability to hold shape thus making the kite quicker to power up by having the ideal wing shape ready at every sheeting angle possible via bar throw or line length adjustment. Skip the next paragraph unless you want to be really confused.
Foil kites can actually bend like I just got done saying they can not. But that bend is pre-set and non adjustable by the user. This is where the bridle comes into play. The bend is 100% controlled by the length and specific placement of the bridles above the pulleys. "Placement" refers to where the small bridles terminate at the kite (kite attachment point), where those bridles come together and attach to the next heavier leaders, then where they attach to the next heavier leaders, then where they attach to the pulley system. An evenly spaced kite attachment point will yield a kite that sheets like a door on a hinge. If you squish (move away from the leading edge) the middle and bottom bridles to where they are closer to the trailing edge, you can make the kite curve at an invariable rate. I say invariable because the user cannot affect this rate with adjustment via bar throw or line length. With the shape being determined in the bridles, there is no adjustment you can (or should) make there if the kite flies well. And by "flies well", I mean that there is no luffing at the edge of or back of the wind window. Luffing or poor flying kites typically indicated a manufacturing defect in the kite related to length or proper placement of bridles. Or it could just be an old kite that was designed before kite designers knew what they know now.
The Ozone "outside trim straps" were most likely an effort to clean up the center line adjustment clutter. Also since the outside lines have less pull on them, they could be made out of a plastic strap adjuster instead of a metal cleat making the system lighter. This was a great innovation by Ozone, again showing their willingness to lead the foil kite industry in technology. But on my 6m and 10m 2010 Access "XT's", I never really liked this adjustment since you had to adjust 2 things instead of one. Doing this on the fly is very difficult, if not impossible if the wind has increased and you want to let the lines out. Also, when trying to control the kite, you pretty much wind up doing one side at a time which will start to turn the kite with the bar straight. I still like the way HQ is keeping the center line adjustment.
You are absolutely right about just needing a bigger kite. I kind of missed that point.
But shortening the leader lines (and thus the steering or brake lines) is EXACTLY the same as lengthening the center lines. It will simply move the sweet spot on the bar throw further up. There is no change in the shape or maximum power of the kite with this modification. Back line or front line length adjustment only affects the sheeting angle accessible in the bar throw.
Windsurfers would know exactly why this is the case because a windsurfing sail has an adjustment that a kite does not. Windsurfing sails depower the same way as a kite, you sheet them in and you sheet them out by adjusting their angle of attack to the wind. But no kite that I am aware of has an "outhaul" like a windsurfing sail. The outhaul is the line that pulls on the clew (back end of the sail) and shapes it either flatter like a board or fuller like a wing. There is no "flatter or fuller" adjustment on a kite, only sheeting in or out via the bar or line length adjustment. You could argue that a kite gets flatter when there is less wind/power in it, but this is not valid because a windsurfing sail or any sail for that matter will do the same at a single outhaul length. A kite is always out hauled to ONE shape when full of air on an open cell foil, closed cell foil, or inflatable. Line length adjustment or bar throw does not affect this.
The only exception to this may be with older single pulley foils like the Apex II. With a single pulley on a foil, you do get some curve change to the kite because you are bending the kite near the center when sheeting it in. But I don not believe that this property was ever exploited by designers to produce a positive performance effect that allowed you to change the shape of the foil for more power. At least I never experienced it. Double pulley foil kites (4 pulleys per kite) have somewhat eliminated this tendency of the kite to bend. This has given us foil kites with less bar pressure and more ability to hold shape thus making the kite quicker to power up by having the ideal wing shape ready at every sheeting angle possible via bar throw or line length adjustment. Skip the next paragraph unless you want to be really confused.
Foil kites can actually bend like I just got done saying they can not. But that bend is pre-set and non adjustable by the user. This is where the bridle comes into play. The bend is 100% controlled by the length and specific placement of the bridles above the pulleys. "Placement" refers to where the small bridles terminate at the kite (kite attachment point), where those bridles come together and attach to the next heavier leaders, then where they attach to the next heavier leaders, then where they attach to the pulley system. An evenly spaced kite attachment point will yield a kite that sheets like a door on a hinge. If you squish (move away from the leading edge) the middle and bottom bridles to where they are closer to the trailing edge, you can make the kite curve at an invariable rate. I say invariable because the user cannot affect this rate with adjustment via bar throw or line length. With the shape being determined in the bridles, there is no adjustment you can (or should) make there if the kite flies well. And by "flies well", I mean that there is no luffing at the edge of or back of the wind window. Luffing or poor flying kites typically indicated a manufacturing defect in the kite related to length or proper placement of bridles. Or it could just be an old kite that was designed before kite designers knew what they know now.
The Ozone "outside trim straps" were most likely an effort to clean up the center line adjustment clutter. Also since the outside lines have less pull on them, they could be made out of a plastic strap adjuster instead of a metal cleat making the system lighter. This was a great innovation by Ozone, again showing their willingness to lead the foil kite industry in technology. But on my 6m and 10m 2010 Access "XT's", I never really liked this adjustment since you had to adjust 2 things instead of one. Doing this on the fly is very difficult, if not impossible if the wind has increased and you want to let the lines out. Also, when trying to control the kite, you pretty much wind up doing one side at a time which will start to turn the kite with the bar straight. I still like the way HQ is keeping the center line adjustment.
Re: Adjusting control line length
Two things to toss in the mix...
The lines will stretch differently between the front and back lines over time. So you might need to compensate for that.
The other thing... on my 12m 09 Liquid Force Havoc, I find it flys the best when I shorten the back lines one knot from recommended setting (maybe due to line stretch). (my 8m 08 havoc is the same way) I can always pull in the sheet strap a bit to get it to equivalent of the stock setup if the wind comes up or for unhooking in light wind (might have a slightly greater tendency to backfly)... but I rarely need to.
Definitely something to experiment with! If you learning it is probably best to stick with the stock setup or ask people questions when your setting up!
The lines will stretch differently between the front and back lines over time. So you might need to compensate for that.
The other thing... on my 12m 09 Liquid Force Havoc, I find it flys the best when I shorten the back lines one knot from recommended setting (maybe due to line stretch). (my 8m 08 havoc is the same way) I can always pull in the sheet strap a bit to get it to equivalent of the stock setup if the wind comes up or for unhooking in light wind (might have a slightly greater tendency to backfly)... but I rarely need to.
Definitely something to experiment with! If you learning it is probably best to stick with the stock setup or ask people questions when your setting up!