The Science of a Wing Chun Punch - Part 2
A short and simple take on the implementation of the WCP. It is performed with the fist in a vertical position with both the elbow and wrist on the centerline. The centerline is a straight line between you and your opponent, emanating from close to the bottom of the sternum to the same point on the opponent. That is not the ultimate target but represents the shortest distance between the two bodies. Much more is involved in the WCP than this, for example: the wave of energy generation using the seven major joints from the ankle up through to the wrist (this is where the power for the "One Inch Punch" comes from); the combined use of the Jin-bo (arrow-step), to name a couple. For the sake of simplicity I'll be focusing primarily on the arm.
The benefits of the WCP are too numerous cover in their entirety so I will only address the points in comparison to the analysis of the horizontal punch in Part 1.
In the picture below the WCP is shown from the top and if you follow the line of force as it would travel down the middle forearm, you notice that it terminates in the middle of the mass of the fist, which, upon impact, the knuckles will compress to a flat striking surface. If any bending of the wrist occurs, it will only bend it outward turning the punch into a palm strike.
Top view
Now let's look at the same alignment from the side. Again, following the line of force, as in the image below, we see there is no offset from center of the contact surface.
Side view
- As there is no offset of the line of force or the angle of the arm in relation to the opponent one is delivering as much force/transferring as much energy, as one can.
- As explained above the WCP has the elbow as well as the wrist on the centerline thus the weight of the body is behind the punch adding a lot more mass and therefore, power, even without an arrow step. Due to this, one can deliver the punch with less tension in the arm, conserving energy.
- Keeping the elbow on the centerline offers protection of the ribs, liver, spleen etc. as well being in the right place for a defensive technique should the need arise.
Now as promised, here is an edited version of my student's Instructor Level paper on the WCP.
"When a punch makes contact, the more acute the angle between a straight punch and the angle of the landing punch will result in a diminution of forward speed and consequentially energy directed straight into the target. Any such angled punch will have less speed than a WCP. This can be mathematically calculated by using vector addition and using trigonometry methods to resolve a single vector into its two components.
A useful physics equation to document punch impact would be that of kinetic energy. That formula is: K = ½(mv²) wherein K= kinetic energy, m= mass and v= velocity. The result of the equation is expressed in Joules. Mass is constant and does not change. It would be the mass of the hand plus probably most of the arm.
What is apparent from the formula is the importance of velocity. Since velocity is squared, changes to velocity create a greater impact than changes in the mass hitting the target. If for example a puncher’s hand/arm doubled in size while retaining the same velocity the kinetic energy would double (2x). However if the velocity doubled while the hand/arm mass stayed the same, then the kinetic energy would quadruple (4x).
The following diagram shows the trigonometry method to calculate the forward velocity of an off angle punch. For purposes of illustration, the speed of the punch is calculated at 10 meters/second.
As seen from the diagram, a punch with a 15º off angle punch will result in the 10 m/s punch velocity dropping to 9.66 m/s. Now when the mass of the hand/arm behind the punch is calculated, then the kinetic energy can be used and compared to the WCP.
For purposes of demonstration an 80 kg puncher is assumed. According to Zatsiorsky, et.al. [Zatsiorsky, Selujanov, 'The mass and inertia characteristics of the main segments of the human body', Biomechanics YIII-B., pp. 1151-1159, (1983)], a male has on average .614% of his body weight in his hand and 1.625% in his forearm. So the sum of these percentages multiplied by the 80 kg bodyweight gives us 1.79 kg, which was arbitrarily reduced to 1.6 kg.
Thus, the mass for kinetic energy is 1.6 kg, punch velocity is 10 meters/second and the off angle punch is variable. The WCP is straight and is therefore 10 m/second. By using these values the below table is created:
Some of these figures are admittedly extreme. However, an earlier section explained the importance of having the elbow in to create a straight punch. The effect can be calculated mathematically. When the elbow is out, a right triangle is formed with the points at the puncher’s shoulder, center of body and the target. If the shoulder joint is 30 cm away from the puncher’s center and the target is 60 cm away, a right triangle is formed. The corresponding vector off angle can be calculated to be 26.6° at the same 10 m/s. By using the kinetic energy formula, the forward energy directed toward the target is 64 Joules – which is a 20% decrease from a straight WCP.
A further example shows the importance of adding speed at the last moment with the wrist joint. Using the above parameters, the WCP had a velocity of 10 m/s and thereby generated 80 Joules of kinetic energy. If the wrist could add 1 m/s in speed to the punch then the generated kinetic energy would be 96.8 Joules – a 21% increase.
Besides the speed aspect the WCP can be employed quickly from the Wu position. It doesn’t give up functionality while waiting to be used and as it goes forward it checks if the way is clear thereby abiding by Wing Chun principals. If the way is clear it strikes if not it goes to a different position or back to Wu." - Sihing Rusty
Thanks for reading
Sifu Pramada
Email if you have any questions or comments: pramada@kungfutao.com