The Tale of the Kite

by Dennis Randall

Kite building and flying is a great family activity that you can safely do with your child. Besides being fun, it's a natural gateway into science and history.

First, a bit of history:

Kites have been with us almost since the dawn of recorded history but the origins of man's first flying machine remain a mystery. Some experts believe the craft of kite flying was born in China nearly 3,000 years ago.

History records the use of kites in battle by armies in ancient China. Back then kites were made of bamboo, paper and silk - materials still in use today. Chinese warrior kites were painted with faces of fierce gods and demons and were designed to hum and shriek in the wind. The effect could be unnerving when used against an unprepared enemy force.

In the predawn hours before battle, the skies over an opposing army would swarm with hundreds of unseen whistling, screaming, and screeching kites. This terrifying display of sound and fury was further enhanced by Chinese spies who infiltrated the camps to spread tales of soul-stealing sky demons.

By daylight, sleep-starved soldiers would gaze upward to see a sky filled with swooping, soaring, and screaming faces - the kite lines all but invisible against the sky. Try maintaining a winning attitude in battle with all that going on over your head ;-)

Now, a sprinkling of science:

Kites are aerodynes and they overcome the pull of gravity and stay aloft by the force of the wind. This aerodynamic principle involved is called lift.

There are two other principles involved in the aerodynamics of kite flight. One is Newton's Law of action and reaction and the second is Bernoulli's Theorem. (Bernoulli was a Swiss mathematician who discovered a wing's secret of lift.)

For a kite to fly, the combined lifting forces must be greater than the weight of the kite. When the wind dies, so does the kite. Without wind there is no resistance for Newton's Third Law and without air moving across the surface of the kite (Bernoulli's Theorem) lift is also gone. When this happens you've got two options. A) Run like the dickens and thus create your own wind, or B) Watch helplessly as your prize kite flutters helplessly to the ground.

Thirdly, a bit of advice:

1) Never fly a kite in a storm or if there is a danger of lightning. Ben Franklin tried this and survived but several others who attempted to repeat Franklin's experiment ended up as crispy critters when struck by lightning.

2) Never fly a kite near electrical wires or transmission lines. Manmade lightning is just as dangerous as the stuff found in nature.

3) Avoid flying kites near the end of runways and airport approach paths with low flying aircraft. Pilots get really annoyed when props and engine intakes get fouled up with kite parts.

Finally, do-it-yourself:

Kites are fairly simple to build and the simple ones are very inexpensive to purchase.