A dart travels in a parabolic curve
I've received a lot of mail from people asking for advice on the technical part of dart throwing. I have also thought about how to make TDT more attractive and informative for my readers. So I decided to do this introduction on the physics behind throwing a dart.
First, let's look on how a dart flies. It travels along a parabolic curve,
the same curve as for instance a thrown stone or a rifle bullet uses.
A dart
travels in a parabolic curve
The curve can be higher or lower, this depends only on how powerful the dart is thrown. A decent throwing technique must guide the dart exactly along this parabolic curve when accelerating the dart, and must guarantee that the dart can continue this curve when it has left the hand.
How must the dart be moved to keep it in the right position? To work this out
we have to look at the mechanics of the throwing arm. It can be exactly
described as a 'machine' of 3 levers attached to each other by 2 joints or
'hinges', and with 1 joint attaching it to a fixed point: 
The highly useful multi-purpose lever-system of the human arm
Looking at the above image, the 2 attaching joints are elbow and wrist, the fixing joint is the shoulder, while the 3 levers are the upper arm, the forearm and the hand.
Those of you who had the misfortune of being tortured by mechanical science in school will remember that this is a very neat arrangement: It can theoretically draw every possible curve within its range when the levers are moved properly, and although the human arm is slightly less movable the parabolic curve is still an easy exercise.
The above image already shows the 'aiming' position when throwing darts. In the following animation you can watch how the 'levers' and 'hinges' work in a decent darts throw, keeping the dart exactly along the curve.
Diagrammatic animation of a neat darting technique using the 3-lever
system
Credits to Tom Neijman from Sitepeople for making
this fine animation of throwing mechanics!
Now with the mechanical basics clear, we can go on to discuss the
Before proceeding you can (and you should!) take yourself some time to watch the above animation carefully. First watch each element on its own, then continue to see the whole arrangement, and how each part of it interacts with the others to keep the dart on course.
The shoulder: This is the only point in the whole process that doesn't change its postion. So you must not move (that's a DON'T, yes!) your body when throwing. The only throwing action comes from your arm.
The elbow: It stays in position when moving the dart backward, and on some point in the acceleration phase starts to go up. This is a very intersting thing, because you may have heard the advice that the elbow should also stay fixed during the throw. This is actually wrong. Again, watch the animation: A fixed elbow would force you to release the dart earlier. This is like the difference in accuracy between a pistol and a rifle. The rifle's longer barrel increases accuracy. The same does the longer guidance of the dart, and as we have to keep the dart on course, too, the elbow must be raised in the later phase of throwing. Also note that the hand still follows the way of the dart after we released it. This makes the release easier, because we don't have to find an absolutely exact release point any more. It doesn't matter much if we drag it out a bit, the dart will still stay in a nice flying position anyway.
The wrist: Wrist action is an often discussed subject. In the animation there is not much of it, so you see it is not absolutely necessary. But most pro players use wrist snap because of one reason: It helps in acceleration. Doesn't the way the 3 'levers' move remind you of a whip? If you do wrist snap the tip of our 'whip' (which is, actually, uhm, the dart) will go faster, and therefore you will be able to move the other parts of the lever system slower, thus put less force in your throw, and this will improve accuracy. But there is one danger in wrist snap: It's one more thing that must be controlled, and so one more source for errors. While most experts and pros use it, I wouldn't recommend it to beginners that don't have the natural gift to control it.
Aiming: Put your eyes, the dart and the target you want to hit in one line. Focus the target, not the dart or that pretty girl/boy just entering the bar. Use aiming points on the target if you like, or aim in a different way, but: Aim!. Most darters do aiming naturally, but surpisingly some beginners don't do from the start. It's a must DO, so do it.
Backward move: Do this, but don't do it too fast. Many beginners fear the necessary loss of aiming during the backward move, but controlling this is only a matter of practice. There are only few successful players out who omit the backward movement, so it's another DO for 99 percent of us. How far you move back is a personal thing, but it's good to move back quite a bit. If you find it comfortable, you can and should move back as far as possible. You can avoid slamming into your eyes or nose by pulling back under your chin or beside your cheek (the one in your FACE, of course!), that depends on your personal technique. A typical error here is not to pull back enough because control of this is difficult, but you will thus sacrifice a lot of acceleration space and accuracy. Better practice more than going the easy way!
Acceleration: Not that crucial as you might think. Do it naturally, and don't do it too fast or with too much force. Do it smoothely in one move and all the way to the follow-through. Remember the elbow coming up. IF you do wrist-snap, then your hand goes forward in this phase until full extension of the whole arm in follow-through.
Release: As wrote above, with the right throwing this comes naturally and is no big problem. If you have troubles with the release point, then most probably you do a technical error, don't raise your elbow or don't do follow-through. This is the critical point for your wrist-snap. The hand must be in the correct angle to the forearm here. If it has travelled further, your dart points down at the release point, and this - well, refer to the 'The Dart' section at the end of this document.
Follow-through: A very important thing. Remember the shotgun-rifle comparison. Best way to follow-through is to end up with your hand aiming at the chosen target. A typical error is to let your arm 'fall down' after the release. Just keep your arm in the straight and slight upward position for a moment, just like in the above animation, and you will get the feeling for follow-through quite fast.
The dart: The real object of our desire is last here. Remember to guide the dart along the parabolic curve. In geometric language, your dart must always be in line with the throwing parabola's tangent in the point of intersection of your hand and the parabola (mph, hope that's even near...). You don't have to tape your throw with a video camera and draw a perfect parabola on the TV with this neat everlast paint to achieve this, it usually develops quite naturally (thank god and our stone-throwing-and-thus-animals-killing-for-getting-yummy-food-ancestor's genetic heritage on throwing parabolas). Keep your attention on the following things: The dart points up in the aiming position. This angle is increased in the backward movement, and it then decreases steadily in the acceleration part. When the dart is released it is nearly horizontally, but still points up a bit. In every circumstances a dart that points down in any of the throwing phases is bad, bad, bad! You got it? That's another DON'T!
Wobble: Almost every beginner's dart wobbles considerably. Pro's and expert's darts hardly ever wobble. Wobbling can have the following reasons:
That's so far my analyzes on the mechanics of dart throwing. As always, I encourage you to write me your thoughts, questions or simple 2cents in the feedback section or through normal mail.