Jetro PirasmepulkulThe Truth Behind Head-heavy Badminton Rackets

In the game of badminton, often regarded as the fastest racket sport, the “smash” is often its most notable and exciting shot. This offensive stroke is utilized more than ever since the introduction of the new “rally-point system” (volleyball-style counting), resulting in a shift in game strategy. Since the game is now shorter in length, players evolve to play a much more aggressive game by focusing primarily on fast and powerful attacking strategies to quickly gain points from the opponent’s weaker returns, rather than the conventional strategy to slowly expose the other’s weaknesses from longer rallies.

This is why nowadays, major badminton racket companies such Yonex, Victor, and Li-ning focus a lot on advertising how their new “offensive play-style” racket will bring the user victory because of the powerful shots it generates1. Please refer to Figure 1 for an example of Yonex’s newest racket and the related advertisement campaign. What makes these rackets so “powerful” to use, per say, is due primarily to the weight on the frame, known as head heaviness. Therefore, players often believe that since a powerful smash is the advantageous shot, in order to get the most powerful smash, a head heavy racket has to be used.

But is this simple logic really true? Would a more head-heavy racket actually deliver a more powerful smash? This experiment aims to investigate the truth behind the current trend in racket development and advertisement that greater racket head heaviness produces greater shuttlecock speed, as compared to head light ones.

The theory that models this relationship is momentum. According to the equation of momentum

P=mv equation 1

The momentum (P) equals the mass (m) times velocity (v). According to the law of conservation of energy, in a closed system that is not affected by external forces, then the momentum of the racket will be equal to the momentum of the shuttlecock. This is seen in the equation:

Vshuttlecock = (m racket v racket) /m shuttlecock equation 2

This equation explains that all of the kinetic energy will be transferred from the racket to the shuttle. In this experiment, the racket will be swung at the maximum possible velocity, and to achieve so, a full body jump smash shot will be used. If vr is kept as a constant and ms stays the same, then mr is the independent variable. Therefore, the equation should be linear in the form y=mx+b, as mass on head increases, the velocity of shuttlecock will increase. To replicate a closed system, the experiment will be conducted in the Rajendra hall without air conditioning fan on.

1

Design:

Variable Measurement/controlIndependent Head-heaviness of racket

Varied by clay and duct tape added to top of frame

Dependent Shuttlecock speedControlled Camera used to record and its

settings Location and lighting Shuttlecock- same tube, same

brand (Yimnex) Racket used (refer to constants

below) Stroke: Smash Smash technique: Full rotation,

full body jump smash in most professional manner. Swing racket with fastest possible arm speed.

Person smashing (Jetro Pirasmepulkul)

Credibility: .

Constants: The racket used in this experiment is Jetro’s main racket, as used

throughout the season.

1

Figure 1- A 2012 advertisement campaign of Yonex’s newest head-heavy based rackest- The Voltric Z-force. This technique is commonly seen in most top-of-line rackets in the market today, that head heavy rackets are for offensive play style. http://www.yonex.com/z/

Grip: Shaft:

Shaft+ Cap:

Head Racket: Figure 2- The racket is the constant of this experiment. These are the specifications of this racket:Brand: VictorModel: Meteor X80Stiffness: Extra stiff 5/5Head Heaviness: Head heavy 4/5Grommet holes: 80Strings: Yonex Nanogy 95Tension: 24 lbs all around. Grip: 1 layer Yonex Supergrap as over grip.

Methods

Procedures

Mel Jetro

Spot Lights Siripong

Figure 3- A photograph showing a side view of the apparatus set up on Jetro’s side of the court. Note that the spotlights are at the same height as the apex of Jetro’s swing. Extra lighting is needed for a better video recording.

Figure 2- Top view diagram of the experimental set up. The arrow on the court represents the direction of Jetro’s jump smash.

After setting up the court according to the diagram, the following procedures were conducted:

1. Both players stretch, rally, and practice smashing until all muscles are loose and ready to play at peak performance.

2. When ready, a new shuttlecock is weighted. Jetro drinks a sip of water to keep hydrated.

3. Siripong Fong (Camera man) stands atop table, holding camera still and records.

4. Mel (Shuttlecock feeder) does a high under arm forehand serve to the center of the court.

5. Jetro jump smashes straight to Mel (no cross-court). Mel does not receive.6. Repeat steps 4-5 six times. Save video. (although only three trials will be

used in data processing, six trials are made to avoid error).7. Measure mass of used shuttlecock. Jetro hydrates himself. 8. A strip of clay is massed, flattened to the top of the racket’s frame directly

on the center, no more than 10 cm long. Duct tape is used to secure the clay to the frame.

9. Measure new weight of racket. 10. Both players do a brief warm up period and practice smashing to get

accustomed to new racket momentum. This is to avoid mishits. 11. Repeat steps 2-7 for new racket weight. 12. Take out the duct tape from racket frame and repeat steps 8-11, for a total

of 6 different racket weights.

Data Processing

Table 1- Raw Data of Racket Head Mass and Velocity Recorded through Apparatus

Mass Added to

Head (±0.01g)

Total Mass of Racket (±0.01g)

Velocity recorded without conversion (m/s)

T1 T2 T3 Average

0.00 94.82 1.80 2.01 1.86 1.89

1.62 96.45 2.41 2.49 2.39 2.43

2.65 97.48 2.62 2.58 2.80 2.67

3.44 98.26 2.73 2.77 2.72 2.74

5.49 100.31 2.81 2.78 2.71 2.77

9.59 104.41 1.66 1.60 1.52 1.59

Figure 4- This is a sample graph for Trial 1 of mass 2.65 ±0.01g. The green line on the high-speed camera video shot is the “reference length”, in the distance that the shuttlecock travels in the video is based upon. This is the length from the T-joint to the bottom of the racket grip cap, measuring a total of 0.252 m. The perpendicular yellow lines are the set origin so that the horizontal yellow line is parallel to the path of the shuttlecock in order so that the velocity can be determined. In the Loggerpro graph, the red dots correspond to the blue dots in the video frame. The blue dots mark the path of the shuttle over 7 frames while each red dot represents the shuttlecock’s position at the corresponding time. The velocity of the shuttlecock is determined using the slope of the linear regression line over the 7 red dots.

Table 2- Processed Data with Converted Shuttlecock Velocity

Mass Added to Head (±0.01g) Average Velocity

(km/h)

0.00 220

1.62 290

2.65 310

3.44 330

5.49 330

9.59 190

The average velocities in this table are converted from the velocity recorded by the high-speed camera. This was done by multiplying the average velocity in the table above by 3.6 to convert m/s to km/h, then by 33.3 to account for the difference in frame rates of the video watched at 30 frames per second (fps) and the rate at which the video was actually taken at 1000fps. Thus, the velocity in this table in km/h is the actual velocity of the shuttlecock produced in the experiment.

Figure 5- This graph shows the relationship between increasing racket head weight and the velocity of the shuttlecock produced from the jump smash. According to the first five data points, this relationship is best represented as a Natural Exponential relationship, where there is an asymptote to the velocity of the shuttlecock as the muscle reaches its maximum contraction speed. The sixth data point is excluded from the curve fit because its value is significantly different from others, and therefore, an outlier.

Conclusion According to the graph in Figure 5 above, this experiment shows that as the mass added to the racket head increases, the velocity of the shuttlecock produced by a jump smash increases as a Natural Exponential graph as well. This relationship is modeled by equation

-118.8 +/- 10.48 ^(-0.5804 +/- 0.1264m) +338.4 +/- 9.002A

and EvaluationFatigueShuttle feather- different angle, different shuttle has different Position and method of hitDistribution of weight added- clay is not totally flat, adding to air resistance, too much weight causes too much flex in racket. Too much flex makes the racket feel like its going to snap, or cannot be Personal conscience to protect racket (snap underload)

Concluding                                       

State and explain a conclusion, including uncertainties, that is supported by your data.  Your conclusion should directly answer your research question.  Do not use the word “prove”, use "show" or "support" instead.  Nothing is ever proven in science.  Your results only support your conclusions.

If possible, include an equation, with uncertainties, showing the relationship between the research question variables.

Compare the results with literature values, including percent error, if appropriate. Discuss any other findings of importance (beyond the research question). State and explain the limits of applicability of your conclusions.  What situations can your

conclusion be legitimately applied to? Justify any data that was dropped during the analysis.

Evaluating procedures

You should discuss 3-4 of the major weaknesses and limitations of your investigation.  Two “weaknesses” to avoid including are “Not enough time”  (If you needed more time, you should have continued outside of class.) and “Human error” (Science is always done by humans, so “human error” is meaningless.  Be specific; explain what exact “error” the humans committed.)

Here are some ideas of what to think about when identifying the major weaknesses. 

Check each step of the procedure to determine if it was imprecise, and HOW the data could have been affected.

Discuss any weakness in the control of important variables. Discuss any weakness in the range, timing, or frequency of measurement. Comment on the precision and accuracy of measurements. State how any of the following might have affected the data/results:

o initial conditions of the specimens or materials

Figure 5- This graph shows the relationship between increasing racket head weight and the velocity of the shuttlecock produced from the jump smash. According to the first five data points, this relationship is best represented as a Natural Exponential relationship, where there is an asymptote to the velocity of the shuttlecock as the muscle reaches its maximum contraction speed. The sixth data point is excluded from the curve fit because its value is significantly different from others, and therefore, an outlier.

o human handling of the specimens or materials (including how the process of measuring might have influenced the investigation)

o time for stabilizing system or between when measurements were taken

Improving the investigation

For each weakness mentioned above, you should suggest a realistic modification to the experimental technique to improve the reliability of the results.

Finally, you should include suggestions for an investigation that would continue from and build on this investigation.