Thursday, July 22, 2010

KITE LINES - strength and length guide for POWER KITES

This guide aims to explain the differences the strength and length of your kite lines can make on your power or traction kite. I'll try to offer guidance on how to select the right lines for your power kite, and also list below all the major manufactures recommendations for power kite lines.


Please see my other guides for sport/stunt kite lines, andthe constructionand ideal materials for making kite lines.


What strength and length of line?

First its important to understand that there is notone perfect set of lines that will suit all flyers and conditions. Many factors can effect it:



The flyers weight - A 50kg flyer may be perfectly suited with lines 25% lighter than the manufactures recommendations, while a 100kg flyer may need 25% stronger lines.
How windy is it?? - is it calm? blowing a gale? or is it gustyand inconsistent?
The desired flying characteristics - do you want the kiteto flyfast? Or slow it down and give more response time?

Contrary to thesport and stunt kitesthe size of the kite is usually the least important factor, in selection of Power Kite Lines.By their nature Power Kites are designed for TRACTION, and hence a single line may have to support:



The entire flyers weight plus extrainertia loads, caused by changes in momentum. For example aboarder changing body position for a trick while airbourne.
The lateral sideways force generated by the weight of rider and buggy being pulled from a low angle. Again these can change considerably with changes in momentum and direction.

Hence power kite lines have to support a loading considerably greater than the flyers weight. However there is a upper limit of size of kite (and hence power) that any rider of a set weight can hold down for a given wind. Hence the strength of lines is by definition more related to the flyers (fully equipped) weight, than the kite size.


Kite manufacturers have to set up the kite to suit a wide range of conditions and flyers. Hence they have to err on the side of caution, and offer stronger and shorter lines as standard. Hence the lines that come with your kite are unlikely to be optimal for you, and the conditions you fly in, and by careful selection of lines you may be able to increase the performance you get from your power kite


Line strength

In general the Strength of the flying lines effect the kite in the following ways:


Stronger lines

Slow the kite down
Allow you to fly in stronger wind
Increase the minimum wind required to fly the kite
May decrease the response in low wind, as the lines sag.
But conversely increase the response in high wind as there is less give and stretch
Weaker lines

Allow the kite to fly faster with less drag
Allow you to fly in lighter wind
Decrease the maximum wind you can fly the kite in
May decrease the response as there is more give and stretch in the lines
May break!
Line Length

On average power kite flying lines are typically in the range 20 to 25. Line length affects the kite in following ways:


Longer lines

Slows the kite down, kite takes longer to respond, and turns slower
May allow you to fly in weaker winds, by finding more wind at greater height, or reach cleaner air above turbulence.
However the opposite can also apply as you need more wind to lift the weight of the lines
Increase the minimum wind required to fly the kite
Will decrease the kite response as there is more potential for stretch
The kite can spend more time in the higher wind part of the power window.
More thinking time to react and recover if something goes wrong.
Shorter lines

Speeds the kite up, giving quicker response
Will increase the kites responsiveness, as there is less stretch in the lines.
Faster through the window, and hence allows alarger kite to be flown in stronger winds as the kite has less time in the more powerful parts of the wind window. This is good for getting upwind on buggy or board
Manufactures recommendations:

The following are the kite manufactures recommendations copied directly from the Manufactures website, and should be taken as a good starting point for selection of lines.



The lines are grouped into type then presented with the same power/brake(in kg) rating.
The recommended length (in metres) is shown in brackets if available.
Four line fixed bridle power kites

100/75kg



Flexifoil Sting (x18m) 1.2, 1.7, 2.4

135/90kg



Gin Yoz (x25m) - 1.8, 2.6, 3.8, 4.8 m
Gin Yoz II (x25m) - 2.6, 3.8, 4.8 m

180/110kg



Ozone Yakuza (x25m) - 2.2, 2.7, 4.3, 4, 5, 6, 7.3 8.6, 10, 12, 14m
Ozone Samurai 2 (x25m) - 2,3, 4, 5, 6,7m
Ozone Fury (x25m) - 2, 3, 4.5, 6 m
Ozone Rio t (x25m) - 3, 5, 7, 9, 11m

190/90kg



U-Turn Helium (x25m) - 1.8, 2.2, 2.6, 3.5, 4.4, 5.5, 6.6 m
U TurnOxigen (x25m) - 2, 2.5, 3.2, 4, 5, 6.2, 7.8 m
U TurnOxigen Pro (x25m) - 2, 2.5, 3.2, 4, 5, 6.2, 7.8, 9.7 m
UTurn Butane (x25m) - 2.5, 3.5, 4.5, 5.5, 6.5, 7.5, 9.0, 11.0, 13.0m
U Turn Nitro Evo2 (x25m) - 2, 2.5, 3.1, 3.9, 4.9, 6.1, 6.9, 7.7, 9.7, 12.2, 15.4m

200/90kg



PKD Buster (x25m) - 2, 3, 4, 5, 6, 7 m
Gin Yoz (x25m) - 6.2, 8.5, 10.6 m
Gin Yoz II (x25m) - 6.2, 8.5, 10.6 m

200/100kg



Flexifoil Rage

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