Power Kite Forum

Line Length

SecondWind - 28-3-2006 at 01:07 PM

Hello all,

Do you use specific line lengths in different wind conditions with your fixed bridle foils?

I flew my 8.5m Blade on 15m lines today. It seems like a good set up for high winds (less power?). I think I'll want a set of 25m lines also for those low wind days.

I was just curious if you guys/gals switch line sets regularly or do you stick with the standard length setup.

JB - 29-3-2006 at 12:32 AM

Hi DaVinch,

I swap between 20m and 30m lines on my CQuads. The longer lines give the kite 'further to fly' so IMO produce a smoother power for longer.

I would also agree, more wind shorter lines, but also smaller kite.

I also find the kite responds quicker with shorter lines.

Just my 2c worth

doomwheels - 29-3-2006 at 11:12 PM

I agree with everything but "more wind shorter lines, but also smaller kite."

True that more wind means flying a smaller kite, but I would suggest longer line allowing the small kite to travel slower through the power. Small kites on short lines in heavy wind causes quick bursts of power and sometimes erratic behavior. For high winds, it's better to have large kites on short lines and small kites on long.

Other opinions?

Tigger - 30-3-2006 at 01:44 AM

I am a cluts; I am not able to draw a straight line even when using a ruler. I find it considerably cheaper in the long run to buy rather than attempt fabrication. Is there anyone that markets shorter lines?

JB - 30-3-2006 at 02:23 AM

Hi doomwheels,

Thanks for the reply. It's got me thinking, that if I was flying my 2.2 CQuad on 20m lines in a high wind and I was finding a bit to much too handle, then swapping to 30m lines would make it easier to handle?

Thoughts anybody??

doomwheels - 30-3-2006 at 12:51 PM

Hi JB,
longer lines will make a kite travel slower through the power zone. It won't pull any more or less, but will pull longer. If your kite is too much to handle (in the sense of pulling too hard), longer lines may add to the prob. Better to fly a smaller kite.

code - 30-3-2006 at 05:00 PM

Doom..so to fly with longer lines is actually a bad practice? I always thought the more line you let out the slower the kite would move, which meant less power. Am glad I'm payin attention to the threads lately.
~Joe

JB - 30-3-2006 at 11:58 PM

Hi doom,

So you are saying that line length doesn't affect power, just the length of time a kite 'pulls for'.

Would you say that if a kite is under-performing then switching to longer lines would be a good idea to increase the power or at least the length of time you get that max power for?

Sorry for what must feel like the Spanish Inquisition but I've never really had a good chat with anyone about line length differences before!

doomwheels - 31-3-2006 at 12:34 AM

Quote:
Originally posted by code
Doom..so to fly with longer lines is actually a bad practice? I always thought the more line you let out the slower the kite would move, which meant less power.
Wait a minute... not a bad practice at all! It just depends on what results you're trying to achieve.

I use longer lines (+30m) with small kites when the wind is really cranking. This combination (small kite/long lines/high wind) allows me to get the max power from a small kite in conditions that I otherwise may not be able to handle a larger kite.

By using longer lines I can increase the amount of time the kite drives through the wind-window (for smoother power transition) and can also fly it higher to get above some of the turbulence often associated with high wind.

*In high wind, a small kite on long lines is good.

Regarding JB's CQuad... if a kite is too big to handle in high wind, longer lines will only prolong its pull - not reduce it. A kite does not fly slower with long lines... it's forward speed is the same. It's just that with longer lines, a kite has more distance to cover and therefore takes longer to travel through the larger wind-window. This results in the kite being powered-up longer before it reaches the edge of the window.

Since large kites produce more pull, shorter lines (20m) COULD be used to shorten the time a kite is powered-up by reducing the size of the window. This could help in high wind conditions by improving line control response and quicker placement of the kite at the window's edge. People sometimes use extremely short lines for cross-downwind speed runs.

*In high wind and in specific situations, a large kite on shorter lines may be beneficial by increasing control and shortening its path through the power zone therefore reducing the time it is powered-up.

Bad practice? The only thing I would advise folks to avoid is using small kites on short lines (less than 30 meter) in high wind. Since the window is reduced, the kite will power-up then drop off very quickly producing sudden bursts of power that may yank you from your feet and drop you like a rock (or more likely drag you on your face for about 10 feet).

Personally, It's been a while since I've used lines shorter than 30m. It feels right to me. If the kite I'm flying becomes too much to handle, I put it away and fly a smaller kite. For safety's sake, I recommend this as a rule of thumb.

doomwheels - 31-3-2006 at 12:51 AM

Quote:
Originally posted by JB
Would you say that if a kite is under-performing then switching to longer lines would be a good idea to increase the power or at least the length of time you get that max power for?
It will increase the time that the kite remains powered-up while flying through the larger power zone, but I'm not saying that this will in any way increase the kite's performance.

I guess we need to define performance. If by that you mean pull and the kite is an efficient design, long lines will only increase the time that the kite is powered-up as stated before. But if you define performance as control and the kite is a poor design, the wind drag from longer lines may even make it worse.

Regardless, I can't think of any good reason to fly large kites longer than 30 meter. Might even be dangerous.

JB - 31-3-2006 at 04:02 AM

Hey, thanks for all that DoomWheels! Great feedback.

I've now decided to swap the lines on my CQuads and try my 2.2 on the 30m lines. I'll let you know what difference I find!

Thanks again for the awesome feedback.

DaveH - 1-4-2006 at 10:17 AM

Guys,
I live inland but often make trips to the beach to fly power kites. When I can't get there sometimes my local conditions make it just plain tough to fly. If the wind is too light I have found (borrowed from trick kiting) shorter, lighter lines allow me to fly the same kite in less wind. That's because they weigh less and produce less drag. Its tougher, however, because the window/power zone is smaller so you have to be on it to maintain forward speed/control. When trying to fly a kite in really light wind keeping the kite moving is necessary to keep it in the air.

Just another way of using the line length thing to your advantage.

Dave

SecondWind - 10-4-2006 at 12:12 PM

Did a little experiment today. I put on a set of 10m lines (~33ft) on my 8.5 Blade in 20mph winds.

The result was kind of fun. I could hold the power and still get some good jumps in. On normal 25m lines I would have been way overpowered.

Certainly not the best option in high winds (smaller kite would have been better), but it was very entertaining...:tumble:

Chip - 11-4-2006 at 10:43 AM

Quote:
Originally posted by doomwheels
Regardless, I can't think of any good reason to fly large kites longer than 30 meter. Might even be dangerous.


Well I can think of one instance where long lines on a large kite is better.

Smack in the middle of Ohio we get lots of crappy wind, and most of my flying fields are surrounded by trees, tall trees. Oh so tall trees. When the wind is high enough you can (with enough effort) fly as normal as long as you lookout for shifty wind directions. But when the wind is down the turbulent low level winds make it very difficult to keep the larger/slower kite inflated and in the power.

Longer lines 45m (150ft) allow the kite to lift aboce the turbulent air to more stable winds and give you real long smooth power. It also makes it steer like a truck, so you better have a real good idea of where you want the kite to go well before you need it there!

My Quadrafoil Competition XXXL (10m) is rigged this way and I buggy with it all summer long in 3-4 mph winds. It's a LOT of work, but it's the only way to scratch the itch!

Oh how I miss the desert! Already looking forward to next year.

-Chip

awindofchange - 11-4-2006 at 11:58 AM

One thing that needs to be considered here is apparent wind also called virtual wind. Apparent wind is wind that is created as the kite flies through the air.

Without going into quantum physics the baisc description is that as a kite flies through the air it creates lift (power). This is from the air rushing over the back of the kite. The faster the air rushes over the kite the more power the kite will produce. This is the exact same design as an airplane wing. The faster the plane goes, the more lift that is generated.

Now, how does that apply to line length? Well, the longer your lines are, the longer the kite can continue on its path without slowing down thus producing power longer as it increases in speed which again will produce more power. When the kite approaches the edge of the window it slows down and thus produces less power. So, thats the basic...now lets add one more bolt to the mechanism.

A high performance kite has the ability to increase power and speed as it flies **up to the point where it reaches terminal velocity**. As you know, when a kite turns from the edge of the window and flies through the power zone, it increases in speed which increases the apparent wind which increases the power. The higher performance the sail is (Usualy higher aspect ratio kites) the faster it will fly through the window. Longer lines will allow the higher aspect ratio kites reach their terminal velocity while shorter lines may not allow the kite to be in the power long enough to do so before it reaches the opposite edge of the window and begins to slow down again. High performance kites will reach speed much quicker than lower performance kites will so lower performance kites could benefit from longer lines more than high performance kites as they will be able to reach max speed and still be in the power zone longer.

That said, *generally* longer lines do have the ability to increase the power output of a kite by allowing the kite to continue to increase speed and apparent wind where shorter lines can decrease the power output of a kite by limiting its speed.

This is of course all limited to the amount of wind you are flying in. There are other factors to consider as well such as longer lines do add some drag and in many cases the excess drag on the lines can even slow down the kite. This all depends on the design of the kite and its performance abilities. I have also experienced situations where the drag on the brake lines of a smaller kite in very strong winds has actually slowed the kite down and I needed to extend the brake lines even more to keep from stalling the kite out. We were actually able to get better performance (power) out of the kite by shortening the lines from 100' to 60' because the drag on the rear lines. We needed to work the kite a lot harder to get up to speed on the buggy but top end speed was a lot better.

Generally speaking (in terms of power output only), shorter lines will allow the kite to move out of the power faster and may possibly limit the top speed of the kite which will decrease the amount of power the kite will produce. The kite will respond quicker which may produce power in bursts. Longer lines will allow the kite to reach max speed and max apparent wind which will produce the maximum power the kite is capable of. The kite will respond slower and power delivery will generally be smoother. This is all based on static flying, once you start moving as in a buggy or other means, maximum speed and aparent wind at the kite end is easier to achieve and longer/shorter lines may not have any difference in power output at all.

That should make things about as clear as mud.....:o

JB - 12-4-2006 at 04:29 AM

Awesome response windofchange!

I was going to do a test last weekend, like Davinch, but no wind unfortunately.

I would agree with the theory that the longer lines allow a kite to stay 'in the power' for longer but whether it actually produces any more power is debatable. I guess a test would be the best thing.

Next weekend hopefully!

JB - 17-4-2006 at 03:20 AM

OK, managed to do a quick test over the weekend. Tried 20m lines on my 6.3 CQuad. I felt that the kite responded more quickly yet lacked the usual oommphh of the 6.3.

Then tested 30m lines on the 2.2 - what a difference from using it with 20m lines - it felt like the 2.2 would stay in the power zone forever, can't wait to try it again on 30m lines in a decent wind.

So in conclusion no amazing results from the test but it probbaly confirms the theories flying around in this post.

I do wonder how 35m lines would feel? Anyone tried longer lines than 30m???

JB - 17-4-2006 at 03:21 AM

OK, managed to do a quick test over the weekend. Tried 20m lines on my 6.3 CQuad. I felt that the kite responded more quickly yet lacked the usual oommphh of the 6.3.

Then tested 30m lines on the 2.2 - what a difference from using it with 20m lines - it felt like the 2.2 would stay in the power zone forever, can't wait to try it again on 30m lines in a decent wind.

So in conclusion no amazing results from the test but it probbaly confirms the theories flying around in this post.

I do wonder how 35m lines would feel? Anyone tried longer lines than 30m???

awindofchange - 17-4-2006 at 01:31 PM

I found that the C-quads always seemed to work better on longer lines. I ended up using 30m (100')on my 2.2 - 3.2 and used 38m (125') on my 4.2 and 6.3. I dropped back down to 100' on the 8.5 and my 10.5 because the power and size of those beasts made me a little nervous.

The 4.2:thumbup: and 6.3 became my favorite kites with the longer lines on them. Give the 125's a try and I think you will love it.

Pablo - 17-4-2006 at 02:12 PM

Longest I've flown on is 60m lines, No where near enough wind to fly my buddys 4m Rad, so we got bored and hooked 2 sets of lines together, no problem flying, really weird experience though, kite was super spongey to control and the power stroke went on forever, huge window to fly in.

JB - 18-4-2006 at 12:27 AM

Thanks for that WOC, I'll look into getting some longer lines for the CQuads! Sounds like it could be fun.