Kite Control Systems - Medium-length-tethered Power Kites

Medium-length-tethered Power Kites

Power kites are controlled by 2 to 5 lines. The simplest systems provide steering by pulling either end of the kite. More lines can provide different functions. These are:

• braking: A line pulling the trailing edge down causes a braking effect that can be used either to make the kite turn quickly if applied to only one side, or to bring the kite down if applied symmetrically.
• adjusting the angle of attack: Pulling on lines attached to the front edge of the kite will reduce the angle of attack and thereby reduce the pull of the kite.
• distorting the kite: Useful when the kite is lying on the surface of the water. A fifth line is occasionally used to do this and thereby makes relaunching much quicker and easier.

The lines attach to different controllers:

Rings or wrist loops

These are commonly found on smaller foils.

Two-line bars

These are found on LEIs, target kites, and other recreational, and special-application kite systems. They almost always have a wrist leash attached to one of the lines so that the kite will come down if the bar is released.

Three-line bars

These are found on some foils. Lines from the ends of the bar attach to either side of the kite and the third line attaches to the rear edge of the foil. This line passes through the bar and is attached to a wrist leash via a cleat to lock the brake off until the bar is dropped. This bar design was never developed by the major manufacturers due to the complexity of the design however an advanced model is now commercially available from K-trac.

Four-line bars

These are found on LEIs, Bows and some foils. This system provides angle-of-attack adjustment. There is usually a semi-permanent attachment, known as the chicken loop, fastened to the kiter's harness via the front lines. Releasing the bar while still attached to the chicken loop causes the kite to assume its minimum angle of attack and therefore minimizes the pull generated. There is usually a safety mechanism so that the kite can be totally depowered by detaching from the chicken loop whilst still hanging on to the kite by a leash attached to one of the lines. There are many variants on this system.

Five-line bars

These are essentially a 4-line system plus a fifth line attached to either the leading edge or trailing edge of the kite. A trailing edge system causes the kite to travel to the center of the power zone and thus re-launch with a lot of power. A leading edge system is used both as a depower and a relaunch device. It can be used to lower the angle of attack for depowering. For relaunch it can be used to assist rolling the kite into the proper position.

Handles

These are commonly found on 4-line foils. Each handle is a bar with a line attached at each end and each handle controls either the left or right side of the kite. They are held at the top where the power lines attach. Brake lines attach to the bottom of each bar and go to the rear edge of each side of the kite. These provide a braking function not an angle of attack function