The Physics of Kite Flying

Kites are fantastic toys. They can dip, swoosh, and are a joy to watch. But have you ever wondered about what makes kites fly? Believe it or not, it’s pure physics!

Here, we will take a look at the physics of kite flying. We will look at how both traditional and stunt kites fly. Hopefully after reading this simple article you will better understand the mysteries behind the flight of kites.

The Conundrum

A kite does not seem that it would fly, does it? Alone, it is pretty light. But just being light (as we all know) is not what makes kites fly. If this were the case then we would never have issues getting them in the air and keeping them there!

Gravity does affect everything, and a kite is no exception to that rule. And no matter how magical they may be to watch, not even stunt kites are actually magic. Instead, physics keeps them aloft. Together, lift and drag keep your kite in the air.

How It Works

Ever notice how your kite flies better on windy days? This is because the wind helps to generate more lift. Lift is the term used to describe the bit of wind that moves over the kite’s surface, and just a bit underneath it.

The thrust (power) of the wind acts to create the lift. Even with the most powerful of winds, the lift that your kite experiences is not very much. This is why they must be made of such light materials. Drag is also generated by the wind. However, instead of lifting your kite upwards, it pushes your kite back down.

A Cool Experiment

Want to experience lift and drag for yourself. The next time you are in a moving vehicle, try putting your hand out of the window. Hold it into the wind. Does it go up? If so, then you are experiencing lift. If your hand moves down in the wind, then you are experiencing drag. Try putting all your fingers together and shaping your hand a bit like a wing. See if you can find the “sweet spot,” where your hand seems to glide in and out of the wind. Chances are it will go up, then down, then back up again.

Other Uses for This Same Principle

It is not just traditional and stunt kites that use these principles to stay in the air. There are other objects that also put lift, drag, and gravity to work to help them fly. Among these things are:

  • Paper planes;
  • Airplanes;
  • Model airplanes;
  • Gliders;
  • Spacecraft (when not in orbit);

These are just a few human inventions that take advantage of lift, drag, and gravity to help them fly through the air. It's not just flying though - other uses of these principles include sailing, keeping time, generating energy, and even running machinery like mills.

Running and Kites

It is a widely held belief that we must run to get our kites soaring into the air. Based on the principles discussed here, running itself does create an air disturbance that is a bit like wind. This initial bit of wind can help your kite to gain just enough lift in order to send your kite skyward. However, a quality kite flown in the recommended wind conditions should require no running and, in fact, very little movement from the pilot.

With modern kites, even indoor flying is possible! If there is wind outdoors and your kite will not fly without running, it may be time for an upgrade.

How Stunt Kites Fly

Are stunt kites any different than traditional kites? Not in terms of the physics of flight. They also use lift, drag, and gravity. But stunt kites are designed to perform tricks and maneuvers in the air. Because of this, the pull on the kite itself tends to be much stronger than a traditional kite. Therefore, the flying lines are often designed to handle much greater force than a single-line kite.

You will also notice that the flying lines on a stunt kite tend to be much shorter than those of a traditional single-line kite. Once again, that is due to the differing goals of each type of kite. Usually, the intention of flying a traditional kite will be to gain as much altitude as possible and allow the kite to move naturally in the wind. A stunt kite's flight, however, is based much more on pilot input and the wind should be much less of a factor.

Try It Out For Yourself!

One of the simplest ways to learn more about the physics behind kites is to try some of your own. There are a great number of kites for sale everywhere you turn. The choice in traditional kites will be much more about pilot preference in design and feel. When it comes to stunt kites, start with the beginner versions and slowly work your way up to more advanced. In either case, quality is the most important factor. So get up, get out and enjoy the magic of flight!