WHAT IS A KITE?
A kite has three essential elements:
- “First, a wing surface shaped or contrived so that it gains lift from the breeze;
- Second, a line or tether that keeps the kite from being blown helplessly away, and in the process, sets the limits of its flying; and
- Third, a bridle that holds the face of the kite at an angle to the wind.” [Brummit]
A kite also needs to be stable enough to stay properly oriented if the wind changes a bit.
There are many different kite styles, but they all have some common features; let’s start with the wing or lifting surface, which is a combination of the kite’s sail and its spars.
Common Features of Kites
Regardless of its shape or size, every kite has a lifting surface called a kite sail. Using the tension on the flying line the sail resists the force of the wind, and provides the lift the kite needs for flight. A sail needs to be both strong and light relative to its size.
A sail can serve as a canvas for beautiful art. It can be made of many different materials, including:
- Paper — rice, construction, letter, tissue, newsprint
- Plastic — trash bags, Mylar, vinyl, polyethylene, Tyvek®
- Synthetic Fabric — nylon, polyester
- Natural Fabric — cotton, silk, linen.
Spars support the structure of many kites. The spars form the framework or skeleton of a kite. The spars may be formed from wood (such as bamboo, spruce, or pine), plastic, fiberglass, or graphite. Depending on the kite style and the location of the spars, they may be rigid or flexible. Soft kites derive their structure from the force of the wind inflating the kite and its pockets, not on a rigid frame, to give the kite its shape. These kites may change their shape depending on the force of the wind. Soft kites have no spars.
The flying line or tether is a key component of any kite. The flying line, connected to the kite in the air and to a person or anchor on the ground, creates tension that allows the kite to use wind energy to keep the kite aloft. Different kites require flying lines of different strengths; the flying line must be strong enough to hold a kite in various wind conditions, but the diameter of the flying line needs to be as small as possible to create a minimum of drag from wind resistance. This is especially true for small, lightweight kites.
The flying line needs to be attached to the kite for the kite to fly. Some kites have flying lines attached at only one point on the kite, but most kites have flying lines attached to a bridle, made from a line or a set of lines that are attached to the kite at several points. The bridle is possibly the most important part of a kite — its proper position and adjustment are essential for obtaining the most suitable flight angle (or angle of attack or attitude) into the wind. The flying line is connected to a certain point on the bridle called the tow point. The bridle is connected to the kite at the bridle point or points. Adjusting the tow point on the bridle can change the flight the angle at which the kite attacks the oncoming wind, allowing the kite to fly in a wide variety of winds. Moving the tow point on the bridle up or down can make the kite fly high or low. (Commercially produced kites often have fixed flight angles with the flying line attached at a single point.) The bridle line is usually the same strength as the flying line.
To fly well, kites need to have stability. Good design and construction can help reduce instability, but other features of the kite, like tails and keels, can also add significantly to a kite’s stability.
Tails help stabilize kites by adding drag at the rear of the kite. Some kites do not need a tail since they are designed to be stable. Even when tails are unnecessary, they may be added for artistic or visual effect. Kite tails can add to the beauty and stability of a kite. There are many possible tail configurations: thin, thick, multiple, u-shaped, balanced, Y-shaped, twisting, drogues, and combinations.
A keel is a piece of material that is a substitute for a bridle. Attached to the sail over the spine (on kites that have a spine), a keel evenly distributes pressure on the spine so that the kite will not bend or lose its shape in a strong wind. Some kitemakers believe a keel also helps stabilize a kite when it slips sideways. A keel often has a number of fixed points where a flying line can be fastened to make adjustments for light or strong winds.