Jetro Pirasmepulkul The 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 isutilized 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 isnow shorter in length, players evolve to play a much more aggressive game byfocusing primarily on fast and powerful attacking strategies to quickly gainpoints from the opponent’s weaker returns, rather than the conventionalstrategy to slowly expose the other’s weaknesses from longer rallies. This is why nowadays, major badminton racket companies such Yonex,Victor, and Li-ningfocus 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 relatedadvertisement campaign. What makes these rackets so “powerful” to use, persay, is due primarily to the weight on the frame, known as head heaviness.Therefore, players often believe that since a powerful smash is the advantageousshot, in order to get the most powerful smash, a head heavy racket has to beused. But is this simple logic really true? Would a more head-heavy racketactually deliver a more powerful smash? This experiment aims to investigate thetruth behind the current trend in racket development and advertisement thatgreater racket head heaviness produces greater shuttlecock speed, as comparedto head light ones. The theory that models this relationship is momentum. According to theequation of momentum P=mv equation 1 The momentum (P) equals the mass (m) times velocity (v). According tothe law of conservation of energy, in a closed system that is not affected byexternal forces,then the momentum of the racket will be equal to the momentumof 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 transferredfrom the racket to the shuttle.In this experiment, the racket will be swung at themaximum possible velocity, and to achieve so, a full body jump smash shot willbe used. If vr is kept as a constant and msstays the same, then mr is theindependent variable. Therefore, the equation should be linear in the formy=mx+b, as mass on head increases, the velocity of shuttlecock will increase. Toreplicate a closed system, the experiment will be conducted in the Rajendra hallwithout air conditioning fan on.
Figure 1- A 2012 advertisement campaign of Yonex’s newest head-heavy based rackest- The Voltric Z-force. This 1 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/Design:Variable Measurement/controlIndependent Head-heaviness of racket Varied by clay and duct tape added to top of frameDependent 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. Head Racket: Figure 2- The racket is the 250mm constant of this experiment. These are the specifications of this racket: Shaft+ Cap: Brand: Victor 260mm Model: Meteor X80 Shaft: Stiffness: Extra stiff 5/5 Grip: Head Heaviness: Head heavy 216mm 165mm 4/5 Grommet holes: 801 Strings: YonexNanogy 95 Tension: 24 lbs all around. Grip: 1 layer YonexSupergrap as over grip.
Methods Mel Jetro Spot Lights SiripongFigure 2- Top view diagram of the experimental set up. The arrow on the court representsthe direction of Jetro’s jump smash. 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.
ProceduresAfter setting up the court according to the diagram, the following procedureswere 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 ProcessingTable 1- Raw Data of Racket Head Mass and Velocity Recorded throughApparatus Mass Velocity recorded without conversion Total Mass Added to (m/s) of Racket Head (±0.01g) T1 T2 T3 Average (±0.01g) 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 tothe bottom of the racket grip cap, measuring a total of 0.252 m. The perpendicularyellow lines are the set origin so that the horizontal yellow line is parallel to thepath of the shuttlecock in order so that the velocity can be determined. In theLoggerpro 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 dotrepresents the shuttlecock’s position at the corresponding time. The velocity ofthe shuttlecock is determined using the slope of the linear regression line overthe 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.ConclusionAccording to the graph in Figure 5 above, this experiment shows that as the massadded to the racket head increases, the velocity of the shuttlecock produced by ajump smash increases as a Natural Exponential graph as well. This relationship ismodeled by equation-118.8 +/- 10.48 ^(-0.5804 +/- 0.1264m) +338.4 +/- 9.002Aand EvaluationFatigueShuttle feather- different angle, different shuttle has differentPosition and method of hitDistribution of weight added- clay is not totally flat, adding to air resistance, toomuch weight causes too much flex in racket. Too much flex makes the racket feellike its going to snap, or cannot bePersonal 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 proceduresYou 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 havecontinued 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 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 takenImproving the investigationFor each weakness mentioned above, you should suggest a realistic modification to the experimentaltechnique to improve the reliability of the results.Finally, you should include suggestions for an investigation that would continue from and build on thisinvestigation.