Wing Chun punches are thrown from the center of the chest with a vertical fist, and basically you just keep your arm relaxed and shoot it into your opponent. It helps to visualize a tube of some kind and keep your fist within that tube. You should leave a point on your chest and strike an opponent the same height as you in the same place, ideally. You shouldn't be extending your arm all the way, but to (this is hard to explain) a distance where your punching elbow is about a fist's width away from your body, give or take depending on where your opponent is.
A straight blast (chain punch) is simply punching with one hand while "cocking" your other fist behind it. Once your first hand makes contact, you drop it down slightly and shoot in the other hand, while simultaneously drawing your original hand back into the position your second hand just left. You can do this for as long as you can hit your opponent, and the punches can be thrown pretty quickly and with good power. How far you draw the hands back depends on your teacher. Mine taught me to draw them to about the middle of my forearm on the other arm.
If that doesn't make any sense tell me and I'll try to reword it, but that's basically a straight blast (from a WC perspective at least) in a nutshell. It might help if I knew where a video of one was, but sadly I don't.  |