How A Powerkite Works

All modern power kites, not only use the wind strength to generate power, but they also use the Bernoulli’s principle. This in simple terms means that, because the upper surface of a power kite is longer than its lower surface the air must pass more quickly over it, which reduces the pressure above this surface creating lift. This is  exactly how an aeroplanes wing works.  The lift, combined with the wind speed means loads more power.  And more power means more fun.

Kites are designed to operate in a given wind range in relation to body weight and skill level. Most manufacturers state their recommendations in the instruction manual.  This means, if you want to fly in all wind conditions, you will need more than one kite and a collection of kites is called a quiver.  Modern kites fall into two main categories, inflatables and foils, with some cross over highbred kites that bridge the gap between the two.

Powerkites or foil kites as they are also known  use the power of the wind to inflate and maintain the kite’s aerodynamic shape, in a similar way to a modern parachute. The kite or wing has two surfaces, an upper and lower, and the shape is defined by the cord. The leading edge has a series of vents in the front. The vents allow the air to pass into the kite.  The materials used allow air to slowly release which maintains pressure in the wing and in turn keeps its shape.

Types of Powerkite

The two main types of powerkite are Fixed Bridle powerkite and De-powerable powerkite.

A Fixed Bridle powerkite is a where the angle of attack of the powerkite is fixed and cannot be changed whilst in flight. The shape of the kite can be changed by pulling on one or more lines thus turning the kite. A fixed bridle powerkite can be either 2,3 or 4 line and can be controlled using either straps, handles or a bar. When controlling a fixed bridle powerkite with either handles or a bar, you have the option to fly your kite with or without a harness.

A De-powerable powerkite is a powerkite where, as well as changing the shape of the kite by pulling on one or more lines to turn the kite, the angle of attack of the kite can be changed whilst in flight thus altering the speed and power of the kite.

The pilots can usually affect the angle or power of the kite in two ways:-

1. pull the bar towards themselves to increase the power and away to decrease it.
2. adjust the trim strap to change the overall power by pulling it towards themselves (sheeting in) to decrease the angle or letting it out(sheeting out) to increase it.

A depowerable kite can only be flown using a bar control system in conjunction with the use of a harness.

Powerkite Control Options

Straps

These are how many people start flying foil kites, with just two lines and the pilot holding a loop at the end of each line to control the powerkite.  Straps may be the easiest system to get the basics of power kite control, but are limited as the pilot doesn't have any brakes to land or reverse launch the powerkite, unlike with both handles and a bar. This control system is ideal for kids and easy fun with powerkites, but not used so often beyond that stage.

Handle Control

Handles look similar to straps in that the pilot holds one handle in each hand, but instead of just one line on each side there are two lines going to each handle.  Handles allow for the best performance and maximum control of the power kite as the pilot has independant control of each line at all times.  They are great for kite buggying and can be used for all land and snow kitesports, but are generally not used for kitesurfing.

Bar Control

Flying on a bar contorl system can be easier to get the hang of than handles. Bars can be used on fixed bridle and de-power kites with 2, 3, or 4 lines. Flying using a bar control system is perfect practise for anyone looking to progress onto either using de-power foils for land or snow based kitesports, or onto kitesurfing as these both use bar control systems. Each bar setup will differ depending on the kite it is used with. Fixed bridle bars work both with and without a harness whilst depower bars will only work with a harness.

De-power Control - A de-power bar system allows the rider to change the kite's angle of attack while flying and therefore alter the amount of power in the kite.  De-power foils can be used for powerkiting, landboarding, snowkiting and buggying.  Of all the bar systems available for foil kites the de-power bar is the most closely related to the kitesurfing bar system, so for anyone looking to get into kitesurfing these are ideal kites for cross-training on land

Number of lines

2 line kites

2-Line powerkites use two lines one held in each hand for control of the kite, just like traditional stunt kites.  Pulling one of the lines changes the shape of the power kite and this change turns the power kite to the left or right.  The simplicity of this style of power kite makes them an ideal introduction to the world of power kiting.

3 Line Kites

Some powerkites have 3 –lines such as the Ozone Imp Trainer kite. This 3 –line kite is effectively a 2-line kite using a bar control system where the two outside lines attaché to the leading edge of the kite while the 3^rd line is simply a break line attaché to the trailing edge of the kite. This allows the user to safely self land the kite by either pulling the on the break line or by releasing the bar .This system is also far safer in an emergency as it allows the kite power to be completely stopped leaving the kite attached to the user via a leash.

4 line kites

4-Line power kites work in the same way as 2 line kites but they have additional lines connected to the trailing edge.  These lines, often called brake lines, allow a greater change in the shape of the kite and give the pilot greater control.  These kites are usually flown on 4 line handles.  A bar will also work although you lose some of the advantages of a four line system.

Aspect Ratio

As well as the different control options and sizes of powerkite available, another thing to consider is aspect ratio. As a rule no matter which control option you choose there will also be a range of aspect ratio available.

The aspect ratio of a powerkite is essentially the ratio of its length to its breadth. The aspect ratio of a powerkite will, to a certain extent, affect the handling and performance characteristics. There are other factors which will affect how each powerkite handles but for now we will keep to the basics.

Low Aspect – short stubby kite. Generally easier to fly than medium and high aspect kites with steadier power and turning. Also usually more stable in gusty winds and easier to relaunch after crashing.

Mid Aspect - Neither short and stubby or long and thin. Mid aspect powerkites are a good compromise offering good amounts of power and lift whilst remaining stable and relatively easy to control with quick turning and fairly easy relaunch capabilities.

High Apect – long narrow kite. Generally very fast flying and turning with maximum upwind ability. High aspect kites often produce large amounts of lift and can be very difficult to relaunch. High aspect powerkites also tend to be quite unstable in gusty winds. All of these characteristics make flying high aspect kites more difficult and dangerous for inexperienced kite fliers.

Safety gear

Powerkite safety is made up of many components including knowledge, skill, site assesment, equipment choice etc with safety equipment being another. Ultimately the choice and use of each is down to the individual, however experience has shown us that the use of safety gear can prevent a minor accident or injury from becoming a serious accident or injury. Often the use of saftey gear is not just to protect us from our own mistakes whilst powerkiting, but also those of others kiting around and with us. We also use safety gear to protect ourselves from mother nature. Whilst we harness the power of the wind with our kites, we do not control that power and so to some extent are always at risk.

A helmet is essential to keep the grey matter in-between your ears and your head in one piece should your head take the force of a minor impact.

Knee and elbow pads are also useful and if you decide to get more extreme, as they will protect these joints during bumps and falls.

Full body armour is also available to help protect shoulders, ribs and spine.

Judge the wind conditions

The wind is affected by objects and landscape features.  Try and avoid flying down wind of any buildings, trees and hills etc.  These all cause turbulence, which in turn makes the kite unstable and unpredictable.  Your first ventures into any aspect of power kite flying should be in light winds. Then gradually you can use more extreme wind speeds as your experience increases.

Which kite to buy ?

Before buying a kite we recommend that you have at least one power kite lesson.  This will not only reduce the risk of injury but a qualified instructor will be able to give all kinds of tips, tricks and advice on what to buy, based on his/her assessments of your ability during the lesson. Synergy Kitesports will be more than happy to help with lessons or arrange test flights and give advice when the time comes to buy.

The kite market today is vast, with many manufacturers having a range of kites for each ability level and for specific disciplines.  To add to the confusion new models are released every year.  Don’t choose a kite because your mate has one or because its used by the world’s best. Get good advice from instructors, dealers and gain experience of testing products, this takes the guess work out of buying.

Still, it’s always nice to acquire a basic knowledge of any subject and we hope this helps.