11/07/2007

UNDERSTANDING KITE DYNAMICS

UNDERSTANDING KITE DYNAMICS
The Wind Window is an important concept you should know before taking a lesson. Knowing it well will help you get up and riding more quickly, and help you understand where your kite should be relative to your body position. These instructions are meant for you to understand the way the kite flies, and should not be a substitute for a lesson from a professional and certified instructor. Only trainer kites of one - three meters in size should be flown alone, and even these in strong winds (+15-20mph) should be flown carefully.
As a general explanation of the wind window, if the rider were standing with his/her back to the wind, the kite can fly in the area, or "window", that is in front of him. If he were to stretch out his arms to each side and sweep them forward, that entire area is the wind window. At the "edge" of the window (the green area in the graphic below), is where the kite generates the least amount of power. If you are landing your kite, or launching your kite, to prevent power bursts your body will absorb by flying through the air, it is safest to launch the kite at the EDGE of the window. You can refer to the Inflatable Kite Tips page, or the Peter Lynn ARC Kite Tips page, for more detailed information on how to launch or land your LEI-type inflatable or Peter Lynn ARC kite at the edge of the window.
Understanding the Wind Window


The red zone is colored in red for a reason. This is the "power zone". In the power zone, the kite is more directly in contact with wind. At the edge, the wind "sees" only the semi-circular arc shape, and produces minimal pressure changes over the kite so the power is kept at bay. In the power zone, the kite's wind profile is larger and pressure changes are more extreme, causing the kite to generate enough power to easily lift you off the ground, or drag you across a field. It is very important to first get lessons, or use a trainer kite (which is very small and generates minimal power in the middle of the power zone) to get used to the forces of the wind on the kite before going out with a kite that can generate enough power to lift you off the ground.
Furthermore, the power of the kite is exponentially related to the speed of the kite, or its "apparent wind". Apparent wind is the wind that the kite sees. So as it travels across the wind window, it "sees" more wind. Furthermore, when kiteboarding, the kite will be moving with you, locked in position, "seeing" more wind than the ground wind-speed. This enables you to keep constant power on the kite. The faster the kite moves, the more power it generates, much more. Therefore, if the kite dives through the power zone at a fast speed, the power can be many times that if it were stalled in that position. Wind is unpredicatable and can change at any moment. It is important to have good kite skills prior to entering the water with, or without, your board.
When you're just starting, the best winds to learn in are approximately 8-15mph. This way, if anything goes wrong, there isn't that much wind to contend with, but its a fair amount of wind to provide enough power to learn in. You want the kite to stay in the air on its own power, so 8mph is the bottom-end. This is for people 160-200lbs. If you're lighter, you want slightly less wind at the top of the range. For someone who is 120lbs, the maximum wind to learn in would be 10-12 mph. If you are learning in 25 mph winds, and something went wrong, things could get significantly worse with the higher winds. Higher winds can throw you or drag you into immovable objects. That being said, it is important to realize as a beginner you should not be "pushing it". Kiting within your limits is the main concern. Do not go out in high winds above 15 mph. Do not go out in waves greater than a 1-2 feet. You should always avoid learning in very cold waters, as well. Someone who is inexperienced and has something go wrong in the water does not want the elements to be working against him, as well.
Learning to Fly
Kite skills are 70% of kitesurfing, or more. Therefore, learning to control the kite is the first thing to do when learning to kitesurf. A trainer kite should be used for this. Trainer kites cost very little compared to real riding gear, and are far more durable. Beginners tend to crash kites when learning to control them. For these two reasons, someone just starting should use the trainer kite. If this isn't reason enough for you, the trainer kite is a lot smaller, so it will generate less power and therefore will be much safer, as well. The trainer kite will help you build your kite skills to eliminate extra risk-factors on the water. Since the kite is the most important aspect of the sport, and can be learned separately, it should be practiced on land with a smaller kite prior to the water....until you can fly the kite without having to look at it.
When you first start flying, the kite should be kept moving. Since you are on land, and cannot ride with the kite on a board in the water, the kite should be steered in a figure-8 across the window as though it was laying on its side. Steering the kite back and forth from your right to your left and back will give you a feel for how the kite's speed causes it to pull harder. This is called "apparent wind". As the kite flies faster, the apparent wind increases. The kite can be kept in the air in real light winds by keeping it moving.
The kite should be steered in a smooth fashion, so the kite is always generating a constant pull. One thing we always tell our students, and its something not many other schools mention, is this:
When sining the kite, or figure-8, you want the kite to generate constant power. In relation, if you're wakeboarding, the boat doesn't surge forward, then slow down, then surge forward...it pulls at a constant pull. This is what you are looking for when flying the kite. If you can master the kite, your learning curve on the water will be minimal.
Flying the Big Kite
To be ready for the water with the bigger kite, you should be able to:
1 - horizontally figure-8 the trainer kite with steady pull through the straight-moves and the turns
2 - vertically figure-8 the trainer kite at the edge of the window at constant power (like in the figure above)
3 - run with the trainer kite to the left/right while sining the kite...and maintaining a constant pull from the kite
Pulling yourself up to your feet from a position lying on the ground is good. Also, never step forward on the sand when the kite pulls. Get used to leaning back and sliding your feet while keeping them in front of you. Your feet in the kiteboard will be fixed into the straps or bindings If you have to step forward on the water, you will be pulled over the board face-first instead because your foot will be in the strap. It is always better to lean back and fall back on your butt, than get pulled over face-first.
If you have enough power, you can also drag around the sand to practice with your sandals on. Keep those feet in front of you. If you can do this easily, you will be much better prepared for the kiteboard that will soon be on your feet.
Using the Kite Control Bar
A lot of beginners attempt to steer the kite as though the bar behaved like the steering wheel of a car. This is not the case. The bar should be pushed, or pulled, with the hands, arms and back used primarily - not the waist or torso. The motion is similar to a boxer "jabbing" with his fists. One arm pushes on one end of the bar as the other pulls on the other end. This is like a teeter-totter in your hands. To turn the kite faster, these movements will have to be more dramatic to pull harder on the steering lines of the kite. In light winds, with large kites, the bar may even have to be steered parallel with the lines, so be sure to get familiar with how to steer the kite smoothly, according to the winds and kitesize you're working with.
As you get better and more familiar with the kite's behavior, you will be able to steer with one hand. Pushing on one end is the same as pulling on the other, so the kite can be accurately steered while using only one side of the bar.
At this point, you should be able to fly the trainer, while talking to a friend and looking around the park, instead of at the kite, without crashing the kite, and always having a fairly accurate "feel" for where the kite is positioned in the air. "is it about to crash into the ground?", "is it sitting at the edge of the window to my left at about a 45 degree angle to the ground?", "is it straight overhead?", "is it moving across the window left-to-right?", "am I accurately flying it in a sine-wave?"...are all questions you should be able to mentally ask yourself, and answer, without looking at the kite. It should be "natural" to you.
Now, you're about ready for the professional lesson.
AFTER THE LESSON
Wind Conditions
The wind conditions should be side-shore. This means the wind is blowing parallel to the shoreline (left-to-right or right-to-left). This is one of the best conditions to kitesurf. Side-onshore is also a great condition to kitesurf. This way, if anything happens on the water and you can't re-launch your kite, you will slowly drift toward shore.
Off-shore and directly on-shore are the worst and should never be used to kitesurf - no matter how experienced. Again, you never know when equipment may fail or break. Don't have the elements stacked against you. If something goes wrong in on-shore conditions, you can be lofted over land and have no control over where you come down. In off-shore or slightly off-shore conditions, you will drift further out to sea. Do not kite in these conditions and never learn in these conditions.
Launching at the Beach
Launch only when the beach is uncrowded, early or late. Have an assistant! You should have learned proper technique from your instructor. If you don't have an area reserved for launching kites, you should be away from the water with your assistant standing in the water if you have an inflatable. For any launch, the best way is side-launch, with the kite being steered over the water once it leaves the ground to the side of the window. That way if a gust hits you will be pulled in the water and not into bystanders. If your beach does not drop off too deep right away, the best thing to do is attempt to keep you and your assistant in the water, or as close to it, where there are no people, with the kite further offshore than yourself. This way, with you in the water, you will only make waves, not bruises and injuries. If you can launch with yourself in the water...do it. Surrounding yourself with water will help soften any drastic power changes the kite may experience from poor wind conditions, or faulty steering by you.
All kiteboarders should checkout the weather in advance of riding and also to be aware of changes while out on the water! Being prepared will prevent mishaps. Do not kite in dangerous winds! Do not kite in severe storms and gusty unpredictable weather! If you see big dark black clouds rapidly approaching, head to the beach and put that kite down!
Getting Through Waves
Learning in waves can be tough. Usually the biggest complaint is getting through the crashing waves to the open waters where there's smoother waters and big rollers you can jump off. To get out there, you can power through the waves on the board, or you can body drag through waves with your board until you're just past them, then strap the board on and havefun. In Chicago, we get the "washing machine" with currents. So if you were to body drag out past the waves, you get severely pounded on bigger wave days, and washed somewhere you don't want to be since there will be a long walk back. Plus, with the break walls and non-beach areas, its not safe being succeptible to the current.
If you are learning in large waves, you will be much better when the water is flat. You need power to get through them, and this can be difficult for a beginner to handle, so if you can't bodydrag, try using a bigger board to keep you on the water, and not in it. Secondly, concentrate on heading a bit more downwind to generate boardspeed earlier, and faster, than normal. Thirdly, when the waves approach, try to time the kite.
Dive the kite as the wave is coming to get power. At the last moment, turn the board more upwind to directly face the incoming wave. Lift up on the front foot to keep the board on top of the wave, rather than in the wave. As this is happening, you should be steering the kite up to 11 oclock to provide lift to get you up over the wave. shift your weight as the front moves over the wave from the rear foot to the front foot to get the rest of the board and your body past the wave. Then dive the kite again turning your board downwind slightly to get you speed to get going again for the next wave. It takes a while, but it will happen. We don't get huge wave faces here, but I've seen them 10 feet high which can be pretty ominous for a beginner. Bottom line is to time the kite's power surge with the wave and board impact. Keep the board as straight into the wave as possible so your body is moving quickly in, over and past the wave.

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