A kite is a heavier than air craft, like an airplane. Kites depend on wind to produce an upward acting force on the kite surface, called lift. A kite must have a strong frame to support the surface material and turn the wind pressure into lift force. Different kites have different types of surfaces and structures.

As with all moving objects, there are certain forces acting on a kite in flight. They are:

- Wind: wind pushes on the kite producing the lift required for flight

- Weight: weight is the downward force pulling all objects toward the earth, called gravity. The weight of the kite is made up of all the materials used to make the kite.

- Tension: tension is the pull of the kite string as the kite is forced away from the person on the ground holding the other end of the string. Tension is broken into two parts, horizontal pull and vertical pull.

- Horizontal pull: horizontal pull is the level pull, measured by the ground distance, of the kite away from the person holding the string.

- Vertical pull: vertical pull is the upward movement of the kite, measured by how high the kite is above the ground.

- Aerodynamic force: aerodynamic force is the pressure that gives a kite its flying ability. It is usually broken into two parts, known as lift and drag.

- Lift: lift is an upward acting force on the kite. Lift is produced when the wind strikes the kite surface at an angle.

- Drag: drag is the rearward force acting on the kite in motion. Drag is produced when the wind pushes on the kite.

The three principle forces acting on the kite are the weight, the tension in the line, and the aerodynamic force.

In flight, the kite is controlled by the flyer, holding a string. The string can also be called the control line, and the flyer can feel the pull in the line created by the wind pushing on the kite. The line is connected to the kite. The surface of the kite is covered by a thin covering of paper, plastic, or cloth, which deflects the wind downward and creates lift and drag on the kite.

Sir Isaac Newton's first law states that every object will remain at rest or in uniform motion in a straight line unless compelled to change its state by the action of an external force.

NASA kite information: http://www.grc.nasa.gov/WWW/K-12/airplane/kitepart.html
Online Kite Model Program: http://www.grc.nasa.gov/WWW/K-12/airplane/kiteprog.html