KITES          

by

John Scavo

This lesson was created as a part of the SMART website and is hosted by the Illinois Institute of Technology

 

Objective:

     This activity is for students of all ages. Students will become familiar with the joy of flying kites.

Kite Safety:

Whether you are flying alone or in a busy park, it is good to remember the 3 C's of kite safety: Caution. Courtesy, and Common Sense.

Parks, beaches, and playgrounds can be crowded, with many different activities competing for space. It is each kite flier's responsibility to fly safely so that we continue to be welcome at our favorite windy places.

Consideration of Others

Do not fly very close to or over roads where drivers could be distracted
Do not fly noisy kites in crowded places
Be careful not to scare animals, particularly horses with riders
Clean up after yourself. Take all of your materials and trash home with you
Be careful not to fly where you might scare nesting birds
Watch out for other people who are not aware that kites can be dangerous
Avoid other kites, kite lines and kite fliers.

Reducing risks

Kite lines conduct electricity so do not fly near overhead power lines
For the same reason do not fly in electrical storms
Flying lines on larger kites can hurt your hands. Watch out for line burns. If you fly a large kite, wear gloves.
Be aware of who or what is behind you as well as in front of you.

Limitations of Self and Equipment

Be aware of the limitations of your skills and strength and do not fly anything too large for the conditions, or try anything too complicated near other people
Be aware of the power and limitations of your kites
Make sure kite anchors are strong and secure enough to hold your kite
Be wary of attaching hard items to kite line - think of what would happen if the line breaks or is cut by another kite
At some point your skills, strength or equipment will fail you, try to fail SAFE!

Why Kites Fly:

LIFT, DRAG, AND GRAVITY:

A kite and airplanes are heavier-than-air object that are flown by the lift created by air in motion over their wings. An airplane relies on thrust from its engines. A kite is tethered in place and needs moving air (wind) to fly.

There are many possible kite shapes. Each of these shapes, and how they use their aerodynamic features (either built in or added on) will determine if or how it flies.

Wind Pressure Wind moving across the sail of a kite creates pressure. Lift results from this wind pressure being deflected along the face of the kite. In other words, the wind pushes up on the kite. Think of wind pressure like a hand, pushing the kite up into the sky and holding it there. If the hand is removed, the kite will fall.

At the same time, wind passing over the top of the kite creates an area of low pressure, like a vacuum, along the back of the kite. This creates a pull from behind.

Wind Pressure

A kite is effected by thrust, drag and by gravity.

Drag is created by wind resistance on the kite's surface (and tail). Drag can also result from turbulence behind the kite. Gravity is the downward force created by the weight of the kite. Thrust is the power of the wind which creates lift.

To fly, a kite needs to have enough lift to overcome gravity and drag.

Lift, Drag, Thrust, and Gravity

All of these forces - lift, drag, gravity, and the thrust of the wind come together in the kite at a place called the center of pressure . And not surprisingly, that's where you tie your kite string. We call this special place the tow point .

By moving the pace your string is attached to the kite on the bridle line, you can change the amount of lift that is created. You do this by changing what we call the angle of attack . This is the angle that the kite leans into the wind.

DIHEDRAL:

The one other thing that is important in understanding flight is something called dihedral . This is a special word from geometry that describes the angle formed when two wings come together.

The dihedral angle of a kites wings helps the kite fly smoothly. If the wings lean back at the same angle, then the wind pushes equally on both wings. If one side of the kite begins to turn further into the wind, then the wind will push harder on that side until the kite becomes stable again. So with a proper dihedral angle built into the kite's design, it will fly properly balanced in the sky. We call that equilibrium .

Dihedral

FLIGHT STABILITY:

Properly balancing the dihedral of the kite, the tow point of the bridle, and even a varying amount of tail will affect the stability of your kite along the vertical (yaw), lateral (pitch) and longitudinal (roll) axes.

Yaw is the rotating action about a kite's vertical axis. This is the imaginary line that goes from the ground up through the kite into the sky. The kite turns to the right or left, just like an airplane turns from the right or the left as you watch it from the ground. Yaw

If the tow point is too far forward, or if the kite is not properly balanced, it may start sliding or rotating. To correct the problem:
 

Pitch is the rotating action about a kite's lateral axis. This is another imaginary line. On an airplane, you can think of the wings as the lateral axis. If a kite has a poor bridle, or inadequate sticks, the wind can distort its shape and create a flapping or pitching motion. To correct the problem:

Pitch

Roll is the rotating action about a kite's longitudinal axis. On an airplane, this would be the imaginary line through the body or fuselage. When an airplane, or kite, rolls, one wing lifts higher and the other is lowered.

A flat kite will be unstable and will tend to dip to one side or the other to reduce pressure on the sails. To correct the problem:

Roll

How to Fly your Kite:

Professor Kite and the Secret of Kites

Kite Flying is great fun and it's easy if you know some of Professor Kite's secrets. So grab your kite and join in the fun. The sky is big enough for EVERYONE!

The first thing you need to do is pick a kite. Fliers carry different types of kites for different winds. Kitefliers enjoy the different experiences each type offers.

Be sure your kite is put together correctly, or it may not fly.

Deltas, Diamonds and Dragon kites fly well in light to medium winds (approximately 6-15 mph) while Box Kites and

stickless Parafoil kites fly better when the winds get a little stronger (approximately 8-25 mph).

Professor Kites General Rules for Picking Kite Days:
Because we don't control the wind, we learn to watch for the right kite flying conditions.

Wind that is too strong or too light is difficult to fly in. A flag or windsock is handy to help you see the wind. About 5-25 mph is best for most kites (when leaves and bushes start to move, but before it really starts to blow).

Flying is most fun when the wind is medium so you can do more than just hold on. You can make your kite dance across the sky by pulling in and letting out the line.

Flying Space should be a clear, open area. Stay away from roads, power lines or airports. Open fields, parks and beaches are great for flying kites. The more room you have, the more line you can let out.

Remember that as the wind goes over and around trees and buildings, it gets bumpy and difficult to fly kites in. Watch out for kite eating trees!

No Storms: Never fly in rain or lightning. Electricity in clouds is attracted to damp kite lines and foolish kite fliers.

Don't Experiment - Fly Safe!

Launching

Professor Kite Explains "How to Get Your Kite to Fly"

Kiters know that a kite has no "spirit" until it has been flown. Even if your kite is only for decoration, it should be flown at least once.

Single Line Kites:

Stand with your back to the wind. Hold your kite up by the bridle point and let the line out. If there is sufficient wind, your kite will go right up. Let the kite fly away from you a little, then pull in on the line as the kite points up so it will climb. Repeat this until your kite gains the altitude necessary to find a good steady wind.

Light Wind? Have a helper take the kite downwind and hold it up. On command, the helper releases the kite and the flier pulls the line hand-over-hand while the kite gains altitude. Practice this high-launch technique.

No Helper? Prop the kite up against a bush, post, or wall. Reel out enough line for altitude and simply pull the kite aloft.

If the kite sinks tail first, there might not be enough wind. If it comes down head first or spins, there might be too much wind. Different kites fly in different winds.

Bridles: If your kite has an adjustable bridle, move it higher (nearer the top) in higher winds, and lower (towards the tail) in lower winds. (Adjust no more than 1/2" at a time.)

Tails: Adding tails to your kite helps it remain stable in stronger winds. Use light-weight materials so you can use lots! Looks great!

Acrobatic Sport Kites:

The Safest Start: Lay out your stunter and lines completely before you launch. Check all connectors, unsnarl and straighten lines and tails.

Check the Bridles: Be sure they are adjusted correctly for the present conditions.

Enough line? Use at least 60' - 100' - so you have enough time to react. Be sure your flying lines are even. If one line is shorter, your kite will think you are pulling on that line and spin in that direction.

To Launch: Step backwards and pull both handles to your side. Be sure to check behind you for obstructions or hazards before backing up.

Control: Pull the left line to make the stunter turn left. Pull the right line to turn right. Hold them even to fly straight. Try not to over-control. Learn to "fly loops" instead of just spinning tight circles.

Lift and Speed: The more to the side of the wind the stunter flies, the less lift and speed it has. While learning to fly, keep the stunter downwind. As you get better, explore the more subtle levels of performance.

Safety: Always stay away from spectators or passers-by. You are responsible for the safe operation of your stunter. Sport Kites should never be flown in crowded areas.

 

Professor Kite's Helpful Hints
(and a few common sense safety rules)
  • Always fly kites away from airports, away from power lines, and never over roads.
  • Always fly away from other people.
  • Remember to be considerate of others.
  • If you tangle lines with another kite, don't yank the line or it might break. Fliers should walk together and the tangle will slide right down the line to where you can unwrap it.
  • If you think you're getting good... Offer to help a friend. Flying is fun... Pass it on.
  • As a kiteflier, you are responsible to think about safety and what you are doing.
Safety

Professor Kite says:
"Never be a danger to yourself or others.
Most of all...Slow down, take it easy, and enjoy!"

Many wonderful people just like you, enjoy the pleasures and fellowship to be found at the end of a kite line. Sharing seems to make the fun even greater.

 

Some kite History:

See You In the Sky!

  

Performance Assessment:

                                                                 

Some great kite reference sites!

http://www.kitetrade.org/

http://www.nationalkitemonth.org/overview/


Forward to John's lesson on Surface Tension.
BACK to Lesson #6 on Dancing Raisins.
Back to the SMART home page.