The punch

One of the most controversial topics of martial arts.

Does the Wing Chun punch have real power?

Well if you've ever been hit by one from someone who knows how to punch correctly I wouldn't have to go on to answer that.
But just in case you hadn't had the pleasure, lets scientifically prove once and for all, that the Wing Chun punch is a force to be reckoned with.

It's all about technique and speed.
The definition of Power is:
Power = Work / time
A standard cross punch, say in boxing no doubt requires more work than a Wing Chun punch. The shoulder and waist are used to propel the punch and therefor certainly feels more powerful. The problem is that power is "Work divided by time" So even though the punch feels greatly more powerful than a Wing Chun punch, a Wing Chun punch can be thrown three times in the time it takes to throw a cross punch.
So what does this mean?
If we used an electronic measuring device that we could punch and get a reading, we may find that a cross punch registers higher than a Wing Chun punch, but it does not mean that it is greater in power. You would also need to measure the time it took to punch. With that a cross punch would need to be triple the result of of a Wing Chun punch just to be equal in power, due to the speed of the punch.

Newton's Third law of motion states:
Every action has an equal and opposite reaction.
So here is where technique comes into it. Lets see how a cross punch and Wing Chun punch are treated when used on a 50kg bag.
When both punches are used a resistance from the bag act against the punch in the opposite direction.

Notice at the point of contact, the arrow represents the bag reaction to the punch. You can see that nothing supports the punch behind the elbow.
The punch gets its stability from body tension and momentum. It is this momentum that makes this punch harder to control, interrupting and stopping the punch accurately is extremely difficult. So the body needs to slow down earlier to avoid joint damage and over commitment. This means that from point of contact to the end of the move the punch tends to slow down.

Here we see the structure of the Wing Chun punch being a lot tighter with the elbow starting close to the centre of the body. When contact is made with the bag the elbow still has the body behind it, giving support and stability to the punch. This is the main reason why the one inch punch works, no momentum is needed because the body supports the punch. This also means that the punch is very controllable, allowing you to interrupt the move if necessary or keep accelerating to the end of your punch. So once you make contact with the bag you don't slow the punch.
A good punch technique can retain maximum speed to the end of the move and stop at an extended position without joint injury.
We can add even further power to this punch by stepping with it, as the step is separate to the upper body we can still apply the same technique to the punch but the supporting structure (the body) also moves in the direction of the punch adding to the end result.

So how does the Wing Chun punch hold up against other punches?
In most cases it is not only faster and as powerful as any other punch, but you also have the ability to interrupt the punch in case your opponent reacts to you. The down side is that it is more difficult to master as it feels natural to put your shoulder into it and the elbow position takes time to get used to. But this is why we can use our other arm at the same time allowing us to simultaneously defend and attack. Now that's gotta be worth the extra effort.