When Bob Dylan wrote about answers blowin’ in the wind, he must have had Saskatchewan in mind: here on the prairies, just about everything is blowin’ in the wind. (Whether that includes answers depends on how well the kids up the street held on to their homework, I suppose.) You can’t change this fact of prairie life, but you can choose how to deal with it: swear at it, or go fly a kite.
For more than 2,000 years, people have chosen to do the latter. They probably started in China, which has the longest recorded history of kite-flying and even had a holiday called Kite Day. Other Asian countries also have strong kite-flying traditions. The Japanese, for example, fly kites on Boy’s Day in May, and the Koreans celebrate the first day of the new year by flying kites from morning until night.
Kites have even been incorporated into religious beliefs. The Koreans sent prayer kites flying free in the hope they would take the evils of the year with them. One Siamese king, believing his special kite was part of his soul, had priests fly it all night long so his soul would be in the heavens while his body slept below.
There’s nothing in the Bible about kites, but in Bermuda they’ve even become part of a local Christian tradition. A 19th-century Sunday school teacher is said to have sent a kite flying free to demonstrate how Jesus ascended into heaven, and ever since, kite flying on Good Friday has been a Bermudan tradition. (Although there is a competing legend to the effect that a minister told members of his parish who didn’t attend church that they could get closer to heaven by flying a kite than by staying home … )
Aside from their supposed mystical properties, kites have a great many practical uses, too. In science, they were an important step in the development of the airplane: the Wright Brothers’ experiments began with kites. Before that, they were used for weather research; between 1898 and 1933, almost everything we knew about the upper atmosphere came from instruments flown on kites. In 1910, for instance, the U.S. Weather Bureau flew a train of box kites to 23,000 feet. Marconi used a kite to support the antenna through which he received the first trans-Atlantic radio transmission, and, of course, back in 1752, Ben Franklin used a kite for some basic research into the nature of lightning.
(If Ben Franklin hadn’t flown that kite in the thunderstorm, making himself famous in the process, the United States might not exist; Franklin’s fame in France, where he was sent as an envoy, was vital to persuading the French to support the Revolution.)
Kites have also been used for fishing, flying artillery observers over battlefields, getting a line over a ravine for bridge-building, and towing everything from Samoan canoes to George Pocock’s Charvolant, a carriage that could carry five passengers at 20 miles an hour Ñ a quite astonishing rate of speed in 1822. (Unfortunately, it never caught on.)
All of this should convince you that kites are far more than children’s toys — which isn’t to say they aren’t a lot of fun! In fact, even in those Asian countries where kites are sometimes imbued with great religious or social significance, they still have a good time flying them. In Thailand, kite-fighting — in which the goal is to cut the string of your opponent’s kite, or otherwise cripple it — is a professional sport that attracts huge crowds.
So how do kites do all this? How do they fly?
Basically, the same way as airplanes do: and that takes us back to good old Daniel Bernoulli, who stated the principle (later named after him) that fast-moving fluids (which includes gases such as air) have a lower pressure than slow-moving or stationery fluids.
An ordinary, flat kite flies best at about a 45-degree angle. At that angle, the wind flows smoothly and quickly over the top of the kite, while the air underneath it piles up and doesn’t move as freely. Slow-moving air has a higher pressure than fast-moving air, so the kite lifts.
The Bernoulli Effect keeps airplanes in the air, too; but an airplane rushes through the air, creating its own wind, while the kite has to rely on the natural breeze.
Like an airplane pilot, a kite flier must also be concerned about thrust, drag and weight. Weight, the downward force of gravity, is obviously a concern because if the kite (or airplane) weighs too much, it won’t be able to generate enough lift to get off the ground. (Unless it’s very large. The largest kite ever flown, in Japan before the Second World War, weighed eight and a half tons and dragged 200 kite fliers along with it!)
Thrust is the force that keeps the air flowing over the airplane wing or over the kite. In an airplane it’s provided by an engine; in the kite, thrust actually comes from the string, which holds the kite in place, keeping the wind flowing around it and generating lift.
Finally, there’s drag, which is the resistance the air puts up to objects moving through it. Since the kite has nowhere it’s trying to go, drag isn’t as much of a problem as it is for an airplane tearing through the atmosphere at hundreds of miles an hour. (In fact, in a kite, drag and lift are almost the same thing.)
Remember all this the next time you see someone flying a kite (or someone tells you to do so), and instead of thinking of kites as toys, think of them as what they really are — the first man-made things to fly, a living legacy of our eternal desire to soar into the heavens.
Not to mention a whole lot more fun on windy days than sitting around swearing.
