The Smash

[Jurong]

Hi BC members,
I am just curious,if an average smasher is given 2 racquets to try out a)82g bal-point at 290mm strung at 24lbs and b) 88g bal-point at 290mm strung at 24lbs. Which racquet will give him a more powerful smash a or b
hope to get some input from you'll.

Regards

Jurong
ps both racquets have stiff shafts.

[Zero_Cool]

should be the 88g coz it's more force...
providing the player can swing both rackets at the same speed...

[franxon]

Hi BC members,
I am just curious,if an average smasher is given 2 racquets to try out a)82g bal-point at 290mm strung at 24lbs and b) 88g bal-point at 290mm strung at 24lbs. Which racquet will give him a more powerful smash a or b
hope to get some input from you'll.

Regards

Jurong
ps both racquets have stiff shafts. you can never tell, without a speedometer or hawkeye.

the 88g racket carries more mass therefore more momentum to transfer to the birdie given the same velocity. but one simply swings a lighter racket faster. so who will carry more momentum? the more massive yet less speedy one or the other one? my physics tells me it can only be answered by experiments. do let me know if i'm wrong.

and my gut feelings are:

1. some people can produce more momentum from a 88g racket, some from the 82g racket.

2. there gotta be a mass range, when rackets are too heavy or too light, the trend which is observed within the range is gonna reverse.

so my suggestion to ur particular case would be: smash with both rackets and let your friends tell you smashes from which rackets are harder (and harder for them to take). If they can't tell the diff, then there's no diff in the pratical sense and simply choose the one you are more comfortable with.

[TonyWdq]

also keep in mind that the string bed, string method, grommets, frame structure are different in different rackets, these variables could screw the equation up further more. I dont believe a $10 1U? Wilson Attacker can make a bigger smash even if its on high tension and the person can swing it fast. Now on the other hand an AT700 can make a bigger boom even the 4U version.

In general, it's better to pick the racket that actually smashes the best in reality (go for a test drive) than looking at specs posted by company advertisements

[cappy75]

Balance point is more important than weight, reason why a light AT700 can generate harder smash is due to its head heavy bias.

[cheongsa]

should be the 88g coz it's more force...
providing the player can swing both rackets at the same speed...

Actually, if the two racquets are swung at the same speed, the smashes will be of the same speed.

[franxon]

Actually, if the two racquets are swung at the same speed, the smashes will be of the same speed.no dear, if they are swung at the same speed, the heavier one smashes harder, given all the rest parameters the same. it is the momentum, rather than speed, that counts. momentum is the product of velocity and mass.

on a snooker table, if you hit a red ball with the cue ball or with a marble at the same speed, the cue ball is gonna kick the red ball farther. but of course, at that split of a second when the string bed hits/bounces the shuttlecock, the physics is far more complicated than that.

[cheongsa]

no dear, if they are swung at the same speed, the heavier one smashes harder, given all the rest parameters the same. it is the momentum, rather than speed, that counts. momentum is the product of velocity and mass.

I am telling you again that if the racquet head speeds are the same, the smash speeds are the same. The shuttle is not colliding with a free racquet, but with the combined system of racquet + player. The player carries so much more momentum that the momentum of the racquet becomes negligible. Shaft, string, and stroke mechanics contributions to the smash speed are very small. The next most important determinant of the smash speed is the mechanical and aerodynamical properties of the shuttle, which is beyond a player's control.

But of course, this is not say that there are no differences between a heavier racquet and a lighter racquet. I have tried, and found that I can smash slightly harder with a heavier racquet. The reason, which sounds paradoxical, is that we can swing heavier racquets faster than we can swing lighter racquets. Strange? Throw a marble and a billiard ball. I will bet almost everyone can throw the billard ball slightly further. Aerodynamics is not the key factor here, but biomechanics.

[tcyc1984]

I am telling you again that if the racquet head speeds are the same, the smash speeds are the same. The shuttle is not colliding with a free racquet, but with the combined system of racquet + player. The player carries so much more momentum that the momentum of the racquet becomes negligible.

According to your reasoning, if you are standing still with both feet contacting the ground firmly during a smash, the combined momentum would be that of the racquet, player's body and the earth! Since the weight of the earth is so huge, any velocity will be insignificant compare to the weight of the earth based on momentum = mass x velocity. So no matter how fast you swing your racquet, as long as your feet are touching the ground, you can generate a smash which can generally go through any body parts or any materials including metals. I've studied a few years of physics in university, I can't say that you are 100% wrong, but I think it just sounds funny (who knows if your smash is actually strong enough to shake the whole world :rolleyes: ) Basically in a stroke, you move your racquet and your arm, and its the momentum of the moving parts which are taken into account. Well, in a jump smash, you move your whole body, so you can say that the weight of your body can be counted. BUT, its the effective movement of your body which is counted. In other words, its the bodily movement in the same direction of the shuttlecock as the racquet contacts the shuttlecock that contributes to the movement of the racquet in the same direction. Thats why jump smashes are always more powerful since your body jumps forward or has a combination of bodily rotation that contributes to the forward movement of your racquet during the impact. Since the effective movement of your body is not as fast compare to the speed you swing your racquet, therefore it only contributes marginally to the momentum of a stroke. The weight of a racquet will have more effects on a normal smash when only your arm is moving, especially for wrist players, and it will have less effects on a jump smash, as your whole body contributes to the momentum of the stroke.

[franxon]

I am telling you again that if the racquet head speeds are the same, the smash speeds are the same. The shuttle is not colliding with a free racquet, but with the combined system of racquet + player. The player carries so much more momentum that the momentum of the racquet becomes negligible. Shaft, string, and stroke mechanics contributions to the smash speed are very small. The next most important determinant of the smash speed is the mechanical and aerodynamical properties of the shuttle, which is beyond a player's control.

But of course, this is not say that there are no differences between a heavier racquet and a lighter racquet. I have tried, and found that I can smash slightly harder with a heavier racquet. The reason, which sounds paradoxical, is that we can swing heavier racquets faster than we can swing lighter racquets. Strange? Throw a marble and a billiard ball. I will bet almost everyone can throw the billard ball slightly further. Aerodynamics is not the key factor here, but biomechanics. no no no. i don't agree with you. there is no way you can throw a billard ball farther than a marble, if no aerodynamics is in the equation.

there will be an ideal racket weight for each person and it varies from person to person, that's why rackets have a weight range from U to 5U. it is virtually impossible for one to tell whether it is 88g or 82g that is closer to Jurong's ideal racket weight.

so much for the speed/velocity issue. as i don't buy your theory that it is the speed.

the physics at that split of a second is complicated. but it is a collision, between the shuttlecock and the stringbed. roughly, the sum of the momentum of the shuttlecock and the racket after the smash (when the shuttlecock is leaving the stringbed) is the same as the sum of the two before the smash (when the shuttlecock is hitting the stringbed) times the effeciency factor.

there is energy loss, and also momentum loss during the collision, much of it is absorbed by the smasher, that is the "impact" one gets when one smashes. this is already taken into consideration in the equation by the effeciency factor.

should the smasher himself appear in the equation? it will further complicate the calculation but it won't overturn the result. like tcyc1984 said, if one smashes standing on the floor, you can also take the floor into consideration, if the court is on the fifth floor, the entire building can show up in the equation too; and if this building is on a cruise, you can bring the whole cruise in; or the ocean in, or even our planet into the equation.

i am just joking. what i'm trying to say is that, it is possible to use a simplified model which only consists of the shuttlecock and the racket for this matter and still get the right conclusion, qualitatively, not quantitatively.

check with your college physics professors if possible. i'd like to hear their opinions too.

[XKazeCloudX]

wow ive read your posts and the physics behind it is amazing. however i would like to ask a more simpilar question. while smashing your torso turns from the side to the front correct? however should u try to turn it forward as fast as u can or just if u do that turn?

[Loppy]

The answer to this question is simple: whichever racket carries more momentum at impact.

Momentum = Velocity * mass, heavier racket carries more mass, but less velocity, and vice versa, so in the end it all comes down to whether the person can swing the lighter racket quick enough to make up for the mass difference. There is a limit to how fast you can swing the racket though, due to the physical limits of our joints, and because drag increases proptionally to velocity, therefore there is a certain optimum weight that gives the fastest smash.

Also, the tension of the strings will affect the momentum transfer, looser strings will allow a longer contact time and therefore a larger % of the momentum will be transfered (aka trampoline effect), tighter strings will have less contact time so less of the momentum will be transferred. The shorter contact time also explains why a higher tension leads to better control and accuracy.

[CoolDoo6]

The problem with speed is that the faster you go, the energy required for the acceleration increases exponentially. At a certain point, a huge amount of energy input produces very little speed gain. Relying solely on speed for smashing mometum/power is not cost effective.

[franxon]

The answer to this question is simple: whichever racket carries more momentum at impact.

Momentum = Velocity * mass, heavier racket carries more mass, but less velocity, and vice versa, so in the end it all comes down to whether the person can swing the lighter racket quick enough to make up for the mass difference. There is a limit to how fast you can swing the racket though, due to the physical limits of our joints, and because drag increases proptionally to velocity, therefore there is a certain optimum weight that gives the fastest smash.

Also, the tension of the strings will affect the momentum transfer, looser strings will allow a longer contact time and therefore a larger % of the momentum will be transfered (aka trampoline effect), tighter strings will have less contact time so less of the momentum will be transferred. The shorter contact time also explains why a higher tension leads to better control and accuracy. i totally agree with you on the momentum part. and i believe that the optimal racket weight differs from people to people, so does the optimal string tension.

however, there are still certain points i'm not so sure. for example, to me looser strings allow a longer contact time and therefore a larger % of the momentum loss instead of momentum transfered, therefore the efficiency factor is low. not exactly like the trampoline.

but all that cannot be over extrapolated. i believe in optimal racket weight. the curve of the momentum (Y axis) versus racket weight (X axis) should be in bell shape.

many people say that higher tension gives better control. but that is not in total agreement with my personal experience.

the accuracy is an accumulative result of: (1) predictability of the bounce by stringbed and (2) the direction control during the collision by the wrist.

higher tension gives more predictable bouces, this is what people talk about most.

but when the string tension is higher, the collision time is shorter and as a result the impact on the player's wrist is more, which means, if the player's wrist is not strong enough to withstand the impact, the shuttlecock is going to go off track. analogy: when one's shoulder cannot deal with the recoil when one fires a rifle, no matter how accurately one aims, one is not going to hit the target.

so, as the tension goes up, factor (1) increases and factor (2) decreases. and vice versa. it is hard for one to say authoritatively when the string tension goes up, the sum of the two will be greater.

therefore the accuracy-tension curve should be bell shape too: there is an optimal tension for one's wrist (given all the rest the same). And, as one's wrist gets stronger, the tension for optimal accuracy will go up as well, i.e. the bell shape curve will shift along the tension axis.

[cheongsa]

Many misconceptions here, let me go through them separately. Need to go play badminton, you know?

The trampoline effect is a silly myth perpetuated in the tennis literature. It never goes away, but let me try to explain why it is rubbish.

First of all, what is this supposed "trampoline effect"? It is the claim that lower tension gives larger dwell time, higher tension gives smaller dwell time, which is then supposed to imply larger dwell time give larger momentum transfer, smaller dwell time give smaller momentum transfer.

Momentum transfer, dp, is related to the force F(t) experienced, and the time interval (0, dt) over which it acts by

dp = int_0^dt F(t') dt'

To make the discussion simpler, let us write this as

dp = Fbar dt

where Fbar is the average force acting over (0, dt).

At first glance, it appears that dp will be larger if dt is larger. But that is not true, because the average force Fbar must be different to give different dwell times.

If we hold everything constant (same racquets, same strings, same tension), then a higher tension (meaning larger Fbar) gives a smaller dt, whereas a lower tension (meaning smaller Fbar) gives a larger dt. So Fbar increases if dt decreases, and vice versa.

It can be shown (simple freshman exercise), that if the collision between a ball and a stationary racquet with massless strings is elastic, dp will be the same, whatever the tension of the string (Principle of Conservation of Energy).

If the racquets with different tensions are moving with the same constant velocity, then by the Principle of Galilean Relativity, dp will be the same as well. (The point I was making in my previous post, in fewer words.)

If the racquets with different tensions are accelerating at the same rate, the physics is the same as the ball falling under the influence of gravity onto two stationary racquets. The dwell times dt will be different, because of the additional effect of gravity. But whatever energy the ball gains on the way in (to the racquets) will be lost on the way out (again, only freshman school physics required here). In the end, dp is the same.

In the real world, things are of course more complicated. After the collision, the massive strings vibrate, the racquet frame vibrates, and energy is also gained or lost from the player. The real collision is definitely not elastic, with the player playing a very important role. However, if we are going to simplify the physics down to just the racquet and the ball (or shuttlecock), the momentum transfer does not depend on the dwell time. In short, no trampoline effect.

But what about real trampolines? The key physics lie with biomechanics. (My point in the previous post, in fewer words than what follows.)

First, let us understand why we cannot rebound on concrete floor. When we are landing on concrete, our muscular and skeletal structures must absorb the shock, so as to prevent injury. Once absorbed, these two biomechanical systems give very little back. Hence no bounce on concrete.

Why then can we rebound on a trampoline? This is because the trampoline absorbs the shock very slowly that our muscular and skeletal system need not participate. Thus, most of the energy is absorbed by the trampoline, and then returned in the rebound.

Conclusion: the concrete floor does not exhibit "trampoline effect" not because it cannot, but because our body cannot endure an elastic collision with concrete and remain intact.

[Loppy]

About the tension - If the strings are at a higher tension, then yes the impact will be greater, but assuming the shuttle hits in the sweet spot, the racket should not twist much. However if a player misses the sweet spot on a high tensioned racket, then the impact on their wrists will be significantly greater, and may lead to injury, inaccuracy and broken strings.

In summary, lower tension leads to more power, higher tension decreases the sweet spot size but increases accuracy if one can hit the sweet spot consistently. Tagsports has a lot of info about string tensions, http://www.tagsports.co.uk/restring-facts.htm

And for the people that are comparing a badminton racket with concrete floors, I think it's pointless cos a racket and a floor cannot be compared. However if you think about trampolines, if the trampoline is too high tensioned, then the bounce will not be as high. If you then decrease the tension, you get more bounce but only up to a certain tension (same with string tensions, it's useless to go below 18lbs or so)

[CoolDoo6]

If it's useless to go below 18lbs, how comes I am using 15lbs and will be going to 14.75 on my next restring ?

[TonyWdq]

If it's useless to go below 18lbs, how comes I am using 15lbs and will be going to 14.75 on my next restring ?

because you are special

[Loppy]

lol, are you sure it's 15lbs? That's crazy, i'm suprised the strings would even stay in place on the racket. I'd really like to see someone play with a racket strung at 15lbs.

[franxon]

If we hold everything constant (same racquets, same strings, same tension), then a higher tension (meaning larger Fbar) gives a smaller dt, whereas a lower tension (meaning smaller Fbar) gives a larger dt. So Fbar increases if dt decreases, and vice versa.i agree. but it doesn't necessarily mean that in the real world, while one goes up and the other goes down, the product of the two, dp, remains the same. it's not straight line parallel to the x axis but a bell shape curve.


It can be shown (simple freshman exercise), that if the collision between a ball and a stationary racquet with massless strings is elastic, dp will be the same, whatever the tension of the string (Principle of Conservation of Energy). as you are aware of too, this is an ideal model which doesn't honestly represent the real world situation.


If the racquets with different tensions are moving with the same constant velocity, then by the Principle of Galilean Relativity, dp will be the same as well. (The point I was making in my previous post, in fewer words.) If the racquets with different tensions are accelerating at the same rate, the physics is the same as the ball falling under the influence of gravity onto two stationary racquets. The dwell times dt will be different, because of the additional effect of gravity. But whatever energy the ball gains on the way in (to the racquets) will be lost on the way out (again, only freshman school physics required here). In the end, dp is the same. well, good point, but you are talking about different string tensions, not different racket weights. how can one accelerate rackets of different weights at the same rate? in the real badminton world, this is in fact the key question to answer.


In the real world, things are of course more complicated. After the collision, the massive strings vibrate, the racquet frame vibrates, and energy is also gained or lost from the player. The real collision is definitely not elastic, with the player playing a very important role. However, if we are going to simplify the physics down to just the racquet and the ball (or shuttlecock), the momentum transfer does not depend on the dwell time. In short, no trampoline effect. good point. it is NOT elastic. while i agree with you that the player plays an important role, his role that i perceive is his wrist, mostly, not his momentum.

back to your two original points:

(1) you can throw a billard ball farther than a marble. can you really? explain to me the physics (biophysics)?

(2) you say same swing speed, same smash. while i say same momentum, same smash. care to explain the physics as well?


But what about real trampolines? The key physics lie with biomechanics. (My point in the previous post, in fewer words than what follows.)

First, let us understand why we cannot rebound on concrete floor. When we are landing on concrete, our muscular and skeletal structures must absorb the shock, so as to prevent injury. Once absorbed, these two biomechanical systems give very little back. Hence no bounce on concrete.

Why then can we rebound on a trampoline? This is because the trampoline absorbs the shock very slowly that our muscular and skeletal system need not participate. Thus, most of the energy is absorbed by the trampoline, and then returned in the rebound.

Conclusion: the concrete floor does not exhibit "trampoline effect" not because it cannot, but because our body cannot endure an elastic collision with concrete and remain intact.

ok, i have a different answer. why we cannot rebound on concrete floor? simply because neither we nor the concrete floor is bouncy. many things don't rebound on concrete floor, a pillow doesn't (well, a little bit only perhaps), a chandelier doesn't either if it does fall down. and no biomechanics for pillows or chandeliers.

and why we can rebound on a trampoline? because trampoline is bouncy. it is that simple. not only we, a pillow or a chandelier can bounce on a trampoline too. no biomechanics.

at least one of the two needs to be bouncy to bounce.

what you say about biomechanics is correct, but it just doesn't answer the question.

[jerby]

If it's useless to go below 18lbs, how comes I am using 15lbs and will be going to 14.75 on my next restring ?
I'm sorry, but it this an argument...or a request to be made fun of?

[franxon]

About the tension - If the strings are at a higher tension, then yes the impact will be greater, but assuming the shuttle hits in the sweet spot, the racket should not twist much. However if a player misses the sweet spot on a high tensioned racket, then the impact on their wrists will be significantly greater, and may lead to injury, inaccuracy and broken strings. even one (a normal player who's optimal string tension is 24 lbs) hits the shuttlecock on the sweetspot of a 30lb string, the impact is significant enough to affect the accuracy. try a racket which is strung 5lbs more than your own racket and you'll find that.


In summary, lower tension leads to more power, higher tension decreases the sweet spot size but increases accuracy if one can hit the sweet spot consistently. Tagsports has a lot of info about string tensions, http://www.tagsports.co.uk/restring-facts.htm
imagine charts with x axis being the tension in lbs, in chart A, y axis is the power, in chart B, y axis is the control, then you have two curves, one being the power-tension curve and the other control-tension curve.

(1) less tension more power suggests a bottom-left to top-right power-tension curve;

(2) more tension more control suggests a top-left to bottom-right control-tension curve.

This is not correct. will you smash harder with a 15lbs racket or control better with a 30lbs racket (let's only talk about the shots that hit the sweetspot) than with the racket you are currently using?

15lbs and 30lbs are extreme, but the model is easily proved to be flawed.


In fact, these two curves are bell shape, with x values of the peaks varie from person to person. in this model, the effective range for tension is actually from 0 to the maximum tension the racket and string can withstand.

the optimal tensions for power and control (the two numbers may not necessarily be the same) largely depend on how explosive your wrist is (for power) and how much impact your wrist can take (for control).

[CoolDoo6]

how can one accelerate rackets of different weights at the same rate? in the real badminton world, this is in fact the key question to answer.


It depends on what you are trying to accelerate: the entire racket or just the racket head. Since badminton is largely comprising of racket head acceleration, the overal racket weight is a less important factor than welght distribution.

Heavier rackets can have an an equal or greater head acceleration than lighter rackets. Imagine a 120g racket with it's entire weight concentrated at the bottom of the handle and the head has zero weight. This racket would have a head acceleration so fast, it would blow your mind. You would be asking yourself: wow, what's happening man, this is like incredible, really incredeeeebubble !:D

[jerby]

if it were that simple...
but a badmintonswing doesn't have one pivot... I count 3: shoulder, elbow and wrist (the fact your whole body moves hardly matters...) so you can't "just accelarate the head" unless you 'dink' (not moving anything except your wrist)...

also, from my personal experience..I find the balance more important than the concrete weight...

[cheongsa]

i agree. but it doesn't necessarily mean that in the real world, while one goes up and the other goes down, the product of the two, dp, remains the same. it's not straight line parallel to the x axis but a bell shape curve.

That is a very strong claim you are making! Do you have data to back it up, or convincing theoretical insight to suggest it?

In general, a graph that goes up and then comes down is produced by two competing factors. These two factors must add, not multiply. The only additive factor I can think of is acceleration (adds to tension), but it is not in competition with anything else, and it surely does not depend on string tension.



as you are aware of too, this is an ideal model which doesn't honestly represent the real world situation.

Certainly, the real world is very messy, which is why we need to exercise discipline in trying to understand what goes on. We must look for the largest effect, then the next largest, and so on and so forth, until all effects are exhausted, or we can't be bothered anymore.

My claim is that kinematics is the largest effect, which is why I restrict myself to the ideal situation of elastic collisions. A real collision between the shuttle and the racquet is highly inelastic, but to even consider the energetics of the inelastic collision, we have to put the player back in.

When I have more time (need to run soon), I can talk about the physics of a kinetic chain, which will hopefully clarify heavy vs light racquets. This will answer your two questions below.



(1) you can throw a billard ball farther than a marble. can you really? explain to me the physics (biophysics)?

(2) you say same swing speed, same smash. while i say same momentum, same smash. care to explain the physics as well?

However, I do have time to answer the question below:


ok, i have a different answer. why we cannot rebound on concrete floor? simply because neither we nor the concrete floor is bouncy. many things don't rebound on concrete floor, a pillow doesn't (well, a little bit only perhaps), a chandelier doesn't either if it does fall down. and no biomechanics for pillows or chandeliers.

and why we can rebound on a trampoline? because trampoline is bouncy. it is that simple. not only we, a pillow or a chandelier can bounce on a trampoline too. no biomechanics.

at least one of the two needs to be bouncy to bounce.

Drop a marble onto a hard concrete floor, and also onto a trampoline. The marble bounces higher (in fact, much higher) from the hard concrete floor than the trampoline. Objects can bounce elastically (if that is what you mean by bouncy) off concrete floors. We can too, if we wrap ourselves tightly in a tight steel shell and don't allow our muscles and skeletons to do anything at all. But we will probably sustain serious injury after rebound.

Every object has elastic response (being bouncy), but the range of this elastic response is different for different material. Steel is elastic up to a very large applied force, afterwhich it deforms. A pillow is elastic up to a miniscule applied force, afterwhich it deforms. As objects are deformed, energy is lost, and therefore cannot rebound very high (or even perceptibly). A pillow does not rebound much on a trampoline: kids can bounce on a bed, but a pillow dropped onto a bed will practically stick there.

Now back to the trampoline. After bouncing on the trampoline for a few minutes, would you feel tired? Yes, because we have expended energy bouncing. Why are we expending energy? Because the trampoline is not really that elastic, so to bounce high, our muscles actually do work against the trampoline, to pack more energy into the trampoline, so that even after a significant fraction is lost, we still recover enough energy from the trampoline to bounce high.

The physics of trampoline bouncing is really that of a forced oscillation (of the trampoline). Some ideas about forced oscillations will be crucial when I get to kinetic chains.

[silentheart]

1) I think we are going off the topic now. Please go back and see the origional question.
2) For the origional question, it is too general. I would like to ask Jurong if my re-phrased question is what he is asking. Given 2 racquets with exactly same design, balance points, material, tension and every factors are the same except the overall weight for racquet A is 82g and B is 88g. Given 1 player swing both racquet @ same max force (same swing) and holding both racquets at same place on the handle. Will racquet B produce higher initial shuttle speed than racquet A with the same shuttle?

If Jurong has no objection over my question and any one agree, let the answering begin.

[silentheart]

I just want to add. The best racquet is the racquet you win most of with.
If racquet X can produce the fastest smash for you but you can not get your drop shot tight to the net. You become one trick dog and you will lose at the end when a player can return your smash or another one smash harder than you do.
It is the player's skill and experience that win the game.

[CoolDoo6]

It can be accepted that the shuttle speed after a collision with the racket is the racket head speed + the captured shuttle speed returned by the string. Since we assume all characteristics, other than the mass, of the rackets are the same, we can safely ignore the captured speed and just examine the racket head speed immediately after the collision. As you will see from my calculations, heavier rackets make a difference. Ding ding ding ding, Doo6's racket is da winnah !!!

[drowsysmurf]

u guys are so funny. u forget the fact that racket bends during a swing which adds more physics to it. if u have a heavier racket with the same velocity of swing, did u forget that the racket would unbend in a different velocity than a lighter racket at the same speed? then given all that facts, u gotta take into account the material used to make the racket and the elasticity of that material and itz ability to unbend and so on so forth... good luck... being an engineering major, i'm still too lazy to go figure all these out... would involve many equations not just f=ma. f=ma is an ideal situation given everything is the same. u all forget wind resistance, friction when bird contacts the string so on so forth...

[minty31]

cooldoo6, so your saying u can generate the same head speed with your 120g racket, in a certain time, as the other lighter rackets in question? that sounds a bit fishy:eek:

minesh

[drowsysmurf]

i believe he is only trying to give an ideal case so the guy will get his answer. in rl... ideal cases... err they don't apply. what u learn in college is a bunch of bs in real life cuz itz way more in depth that the general crap u learn.


cooldoo6, so your saying u can generate the same head speed with your 120g racket, in a certain time, as the other lighter rackets in question? that sounds a bit fishy:eek:

minesh

[silentheart]

I am very sorry CoolDoo6, your calc is all wrong again.
1) if same force is given (ie sam torq), racquet head acc will not be the same for light and heavy racquet.
2) just like drowsysmurf said, racquets shaft band. because the head mass for lighter racquet is lighter, the shaft will bend differntly than heavier racquet (not too much, so this factor can be skiped).
3) I thought you posted before that your fake light headed ti-10 racquet smash faster than the head heavy real ti-10. what happen to that observation?

[CoolDoo6]

The table ignores the returning of the captured speed, which is the function of the string and racket flex. Different rackets+string combo returns different amount of captured speed. A light racket with higher return can compensate for the missing weight. But lighter flexible rackets have lower stability resulting in poorer accuracy.

My claim for the fake was that it offered comparable power but with superior defence. Although I should add: with lower accuracy.

Given the same torque, my heavy racket would have higher head speed than the 2 lighter rackets in the table. The racket was specifically designed to have increased head speed. The figure in the table is the worse-scenario for my racket. In practice, the after-impact speed of my heavy racket would be higher than indicated in the table. But i wouldn't like to brag, you know ? Or, jerby might come and laugh at me.

[franxon]

first of all, thank you for your reply and i'm waiting for your more detailed physics. i don't mind, if not will be happier, to be proven wrong, as long as I get the CORRECT answer, it doesn't matter where it is from.


That is a very strong claim you are making! Do you have data to back it up, or convincing theoretical insight to suggest it? well, i drew the graphs in the previous post with logic, reasoning and some common sense, no maths, no physics.


In general, a graph that goes up and then comes down is produced by two competing factors. These two factors must add, not multiply. are you sure?;) i have dozens of examples to prove otherwise.


Certainly, the real world is very messy, ...

My claim is that kinematics is the largest effect, ...

When I have more time (need to run soon), I can talk about the physics of a kinetic chain, which will hopefully clarify heavy vs light racquets. .. ok i'll wait for that.


However, I do have time to answer the question below:

Drop a marble onto a hard concrete floor, and also onto a trampoline. The marble bounces higher (in fact, much higher) from the hard concrete floor than the trampoline. Objects can bounce elastically (if that is what you mean by bouncy) off concrete floors. We can too, if we wrap ourselves tightly in a tight steel shell and don't allow our muscles and skeletons to do anything at all. But we will probably sustain serious injury after rebound.

Every object has elastic response (being bouncy), but the range of this elastic response is different for different material. Steel is elastic up to a very large applied force, afterwhich it deforms. A pillow is elastic up to a miniscule applied force, afterwhich it deforms. As objects are deformed, energy is lost, and therefore cannot rebound very high (or even perceptibly). A pillow does not rebound much on a trampoline: kids can bounce on a bed, but a pillow dropped onto a bed will practically stick there.

Now back to the trampoline. After bouncing on the trampoline for a few minutes, would you feel tired? Yes, because we have expended energy bouncing. Why are we expending energy? Because the trampoline is not really that elastic, so to bounce high, our muscles actually do work against the trampoline, to pack more energy into the trampoline, so that even after a significant fraction is lost, we still recover enough energy from the trampoline to bounce high.

The physics of trampoline bouncing is really that of a forced oscillation (of the trampoline). Some ideas about forced oscillations will be crucial when I get to kinetic chains. all i tried to say with my pillow example is that, no BIOmechanics. biomechanics can't explain lifeless objects. a chandelier deforms when it drops on the floor but nevertheless, it's very inelastic collision. it doesn't bounce and there's no biomechanics.

marble or steel ball, concrete floor or trampoline, when collide, deform. kinetic energy is hence transformed into potential energy and back to kinetic energy to rebound, with different efficiencies. and how do you think the objects store the potential energy? by deformation. deformation is simply the change in shape due to applied forces. the appliced forces can be tensile, compressive, bending or torsion. in the context of badminton, it is compressive (stringbed), bending (shaft and to a little extend, the frame) and very little torsion (shaft and frame when hit off-sweet-spot).

deformation first ungergoes elastic, then plastic then fracture where it can't get back any more. you used "deform" when you meant "fracture".

btw i don't really like the trampoline analogy for badminton stringbed at all.

[drowsysmurf]

this is where i come to say... WHERE THE HECK DO ALL THESE TERMS COME FROM? BIOMECHANICS, BIOPHYSICS? bio deals with life... the body of animals, plants, tissues. how does biomechanics and biophysics work on a racket... you guys really have to explain it to me. i would understand if u say how they work on the arm, waist, legs, wrist. but then again, meh <.<;;;
here's biophysics: http://en.wikipedia.org/wiki/Biophysics
and here's biomechanics: http://en.wikipedia.org/wiki/Biomechanics
-_-;;; i feel noobish for not knowing how these terms apply to the discussion.

[jerby]

The table ignores the returning of the captured speed, which is the function of the string and racket flex. Different rackets+string combo returns different amount of captured speed. A light racket with higher return can compensate for the missing weight. But lighter flexible rackets have lower stability resulting in poorer accuracy.

My claim for the fake was that it offered comparable power but with superior defence. Although I should add: with lower accuracy.

Given the same torque, my heavy racket would have higher head speed than the 2 lighter rackets in the table. The racket was specifically designed to have increased head speed. The figure in the table is the worse-scenario for my racket. In practice, the after-impact speed of my heavy racket would be higher than indicated in the table. But i wouldn't like to brag, you know ? Or, jerby might come and laugh at me.
you're saying you accelarate your heavy racket faster than a light one? errr... Newton disagrees...
now you can counter than by saying it's because it's headlight..But what does headlight mean?
Headlight means most/'all' the mass is at the bottom, yet you hit the shuttle with the 'top'...
So when it comes to your momentum calculation you treat your arckets as a particle (every force acts upon the same point, no moments, no torques, just dead on, like your train analogy)
but when it comes to your swing/wrist torque, then it's not a particle, then it's headlight...

[CoolDoo6]

you're saying you accelarate your heavy racket faster than a light one? errr... Newton disagrees...

Well, your Mr Newton didn't play badminton. If he did, he would realise rackets with lower MOI have superior angular velocity. For simplicity sake I did not employ MOI and angular velocity for the table as these were close enough to linear velocity and momentum at the point of impact.

[silentheart]

Well, your Mr Newton didn't play badminton. If he did, he would realise rackets with lower MOI have superior angular velocity. For simplicity sake I did not employ MOI and angular velocity for the table as these were close enough to linear velocity and momentum at the point of impact.

True, Sir Isaac Newton (and that is a Sir to you for you British) do not play badminton. However, CoolDoo6 you don't know classic physic either.

There is no need to resopnd to any of your post on this question.

[CoolDoo6]

True, Sir Isaac Newton (and that is a Sir to you for you British) do not play badminton. However, CoolDoo6 you don't know classic physic either.


Since you appear to know classical physics, would you like to use it to prove a racket with lower MOI doesn't produce higher angular velocity ? As you have the authority of Mr Sir Issac Newton on your side, it shouldn't be that hard for you to prove.

[eggroll]

because you are special

Yes, Special OLYMPIAN!

[GunBlade008]

Heavier racquets do not generate more velocity than light racquets. CoolDoo6, in your table, Your logic suggests that if there were a racquet so headlight, that all the weight distribution would be concentrated near the handle. Which would make the racquet head have 0 weight. Mass is needed to generate force, if the weight is 0, there would be no repulsion, no velocity and no shot.

The weight that you hold near the handle would still be a pain to move around, it is as if you are taping a dumbell to a racquet head, holding the dumbell and trying to hit a shuttle. Producing more power with a 120g racquet is overexaggerated, you also forgot to include the ability of one's swing power to generate power. Yes, in some terms, heavier racquets do produce more power, but to an extent, nothing past 90g. After that, one's ability to generate enough swing power would greatly be affected in a negative way. Thus making the "potential power" of a heavy head light racquet useless (Unless you change the laws of physics).

Though we do not have Sir Issac Newton here with us, I think everyone on BC can disregard your post/opinions regarding this matter because until you have concrete proof through a means of a speed radar gun and video, there is no proof at all that either Fu Haifeng, you, nor anyone else can produce more angular velocity with a 120g racquet than with say, a 90g racquet.

[franxon]

Since you appear to know classical physics, would you like to use it to prove a racket with lower MOI doesn't produce higher angular velocity ? As you have the authority of Mr Sir Issac Newton on your side, it shouldn't be that hard for you to prove.

it is either you didn't mean what you said or i didn't understand what i read.

but to me, a racket in my bag doesn't have any MOI at all. and a racket itself doesn't produce/generate any angular velocity either. it is the player who gives the rackt a velocity, a momentum and an energy to carry when he swings it.

MOI and angular velocity are NOT properties of a racket like weight or balance point or shaft stiffness.

that comes to the question: you are actually claiming that you can accelerate a heavier racket faster. that is what Sir Issac Newton would never agree and Newton does not need to play badminton to develop some physics for badminton.

[jerby]

Cooldoob's reasoning is (if I plow through the other stuff) pretty basic if you ask me:
-heavier rackets generate a lot of momentum
-by making it headlight you can swing it fast
-headlight and heavy si the ultimate combination!

though the same reasonign can apply to the opposite stuff
-ultra-light rackets accelarate faster
-very headheavy rackets have a lot of momentum (or MOI, or whatever is the flavor of the month)
- ultra light and very headheavy is the ultimate combination!

it's like rotating between concrete weight and balance and mix and match to get your results...

[CoolDoo6]

that comes to the question: you are actually claiming that you can accelerate a heavier racket faster. that is what Sir Issac Newton would never agree and Newton does not need to play badminton to develop some physics for badminton.

The claim is a heavy low MOI racket can have a greater angular velocity than a light racket with high MOI. If you don't understand where MOI comes in, try follow your coaches advise and use more wrist.

[jerby]

so how does one, theoretically, "reduce MOI" by ádding mass?

apart from the fact adding mass increases an object moment of inertia...

and the "use more wrist" is very 1987...have you ever watched Taufik Hidayat, Lin Dan or Peter Gade smash? ;)

[CoolDoo6]

so how does one, theoretically, "reduce MOI" by ádding mass?

apart from the fact adding mass increases an object moment of inertia...


If you spend more time in skool studying Newton, perhaps one day you will have an MOI reduced racket too. Until then, you can do as the others do and proclaim blindly that you know classical physics.

The Honorable Mr Sir Isacc Newton announces that Doo6's racket is da winnah !!!!

[mojopin]

hmm.. i assume you realise that you cant measure the moi of a racket.. just ... as a racket sitting there... because like.. you cant measure inertia in its strictest sense.
if you understand it as the "amount of resistance to change in velocity" ( which is technically incorrect) your actually confuse if with mass, which you CAN measure ,which brings us right back to where we began. which racket is better for smashing. And to that i say, take them on court and give em a lash and find out. the physics behind will send you to your deathbed.

[drowsysmurf]

once again, please refer to ur resources. for those that do not know MOI = moment of inertia. if you want to know a bit more, go to: http://en.wikipedia.org/wiki/Moment_of_inertia
or else you can always be a mechanical engineering major, architectural engineer, civil engineer and maybe some others. these majors will guarantee you to pick up statics and dynamics which is the more in-depth physics. MOI... err... your body mass is >>> than racket mass... MOI? lol? like i said in my previous post... itz almost impossible to "measure" it. first off, too many factors to take in. second off, different time = different events. i highly doubt you can create the exact same scenario of swinging (unless your a machine)

[jerby]

If you spend more time in skool studying Newton, perhaps one day you will have an MOI reduced racket too. Until then, you can do as the others do and proclaim blindly that you know classical physics.

The Honorable Mr Sir Isacc Newton announces that Doo6's racket is da winnah !!!!
by that reasoning..why not make it 200grams?...maybe more:p

[Gollum]

I'm so glad I'm not here, and therefore no longer need trouble with such nonsense :p

[franxon]

I'm so glad I'm not here, and therefore no longer need trouble with such nonsense :p gollum, write a textbook-like article on it and make it sticky.

[CoolDoo6]

by that reasoning..why not make it 200grams?...maybe more:p


Ahhh, but I am already happy with what I've got and looking for ways to reduce power slightly. Too much power is bad for you, don't you know ?

[jerby]

theoretically then...by your formulas you will keep on smashign harder if you keep adding mass, right?

EDIT: why would one have 'too much power'...I wouldn't be bothered if I could smash 300km/h ;p

[CoolDoo6]

theoretically then...by your formulas you will keep on smashign harder if you keep adding mass, right?

EDIT: why would one have 'too much power'...I wouldn't be bothered if I could smash 300km/h ;p

Adding mass reduces transition speed, ie, when you move the entire racket from one side of your body to the other. Changing this parameter would affect the defence. Since in a typical rally the ratio of time the racket is in transition is relatively small compared to when the racket is in a swing where the advantageous MOI comes into play, by sacrificing a little transition speed you get a disproportionate gain in MOI reduction (the ratio being the multiplying factor). The amount of mass to add depends on how much transition speed reduction you can tolerate.

There is an element of transition in every swing. Going overboard with the mass will eventualy affect the swring. The key is getting a balance.

Too much power means too many shots go out. It would take too long to train power control. I find it easier and quicker just to reduce power on the racket rather than on my arm. I have just restrung my back up racket 1/4 lb lower lower at 14.75 lbs with 1/8lb increase in string bed stiffness. The racket should have better smashing power and lower clearance power than my main racket. Will see tonight. How very exciting !

[jerby]

you do realise most people cán control the depth of their shots?

[Athelete1234]

Heavier racquet= more mass acting on shuttle= more power
Lighter racquet= faster swing speed= more power.

It depends on what kind of player you are really.

[eggroll]

A heavier headed racket will have more power than lighter headed racket if you can swing both at the same speed. The heavier headed racket will be better on off center hits because it will have a higher MOI at impact as it will resist twisting better than a lighter headed racket IF the weight is distributed properly around the perimiter of the head and the flex of the racket head is designed properly. Getting the combination of weight and flex is most important not just weight. Of course flex of shaft comes into play as well. The player, contact vectors, etc.

In the end find a racket you like, buy a couple and play with them until they break. Then hope they are still around so you can buy more. If not have fun finding a new model that would most likely be better!

[CoolDoo6]

you do realise most people cán control the depth of their shots?

Yes, yes, of course. So can I. Except my way doesn't involve training and the result is immediate. As predicted, my back up racket smashed harder and no shots went out the back tonight. I reconfigured the grip to thicken the bottom half before going to the club. That increased the racket weight to 125g. I was a bit worried what the extra weight would do. As it turned out, the biggest surprise of the night was that my defense was superb. The extra weight seemed to have no negative impact. The conclusion I drew at the end of the night was that the racket could be further optimised with the string tension dropping to 14.5 lbs. But that isn't going to happen until the string breaks in 9 months time. If the back up racket performs equally well for a few more nights, it will become my main racket and the heaviest I ever used.

[eggroll]

This thread is whacked! ...and not in a good way...

[GunBlade008]

CoolDoo6, I still see no proof or evidence supporting your theories or your claims that you performed well with it.

[jerby]

does it matter? if it works for him, I'm cool with that...

the problem (for me) arises when he claims his rackets as the penultimate, best racket for everybody...
and the fact his only way to get "better" is by 'modding' his rackets...is just sad...

[Kelvin]

its on specs now :D:p:eek:

[CoolDoo6]

the problem (for me) arises when he claims his rackets as the penultimate, best racket for everybody...
and the fact his only way to get "better" is by 'modding' his rackets...is just sad...

I don't remember claiming my rackets are the best for everybody. In fact I want nobody to have rackets like mine. Hence I have deliberately withheld information on precisely how my results can be achieved. Any details I reveal are in general terms and are just clues. These clues by themselves will get you no where. But if you really start thinking, the clues can help.

I consider it sad that people have so little clue about their equipment. After all we are in an equipment forum discussing merits of equipment.

[jerby]

ghehe, nice touch....the personal attack ;)

though I don't hide behind terms like MOI, momentum, or UHMG...I just demo rackets and find one I like...

In my current case I somehow fell in love with a D500...it's 670mm long (too short, I though) 86grams (too light, I thought) slightly headheavy (meh, should be more, I thought) and stiffish....

then, I played...and liked it a lot and I switched...what's there more to equipment...it's not rocketscience..

[drowsysmurf]

nope...rocket science won't even help you if ur equipment is gonna be hurting ur arms because some arms just hate stiff rackets =P

[Shifty]

Many misconceptions here, let me go through them separately. Need to go play badminton, you know?

The trampoline effect is a silly myth perpetuated in the tennis literature. It never goes away, but let me try to explain why it is rubbish.

First of all, what is this supposed "trampoline effect"? It is the claim that lower tension gives larger dwell time, higher tension gives smaller dwell time, which is then supposed to imply larger dwell time give larger momentum transfer, smaller dwell time give smaller momentum transfer.

Momentum transfer, dp, is related to the force F(t) experienced, and the time interval (0, dt) over which it acts by

dp = int_0^dt F(t') dt'

To make the discussion simpler, let us write this as

dp = Fbar dt

where Fbar is the average force acting over (0, dt).

At first glance, it appears that dp will be larger if dt is larger. But that is not true, because the average force Fbar must be different to give different dwell times.

If we hold everything constant (same racquets, same strings, same tension), then a higher tension (meaning larger Fbar) gives a smaller dt, whereas a lower tension (meaning smaller Fbar) gives a larger dt. So Fbar increases if dt decreases, and vice versa.

It can be shown (simple freshman exercise), that if the collision between a ball and a stationary racquet with massless strings is elastic, dp will be the same, whatever the tension of the string (Principle of Conservation of Energy).

If the racquets with different tensions are moving with the same constant velocity, then by the Principle of Galilean Relativity, dp will be the same as well. (The point I was making in my previous post, in fewer words.)

If the racquets with different tensions are accelerating at the same rate, the physics is the same as the ball falling under the influence of gravity onto two stationary racquets. The dwell times dt will be different, because of the additional effect of gravity. But whatever energy the ball gains on the way in (to the racquets) will be lost on the way out (again, only freshman school physics required here). In the end, dp is the same.

In the real world, things are of course more complicated. After the collision, the massive strings vibrate, the racquet frame vibrates, and energy is also gained or lost from the player. The real collision is definitely not elastic, with the player playing a very important role. However, if we are going to simplify the physics down to just the racquet and the ball (or shuttlecock), the momentum transfer does not depend on the dwell time. In short, no trampoline effect.

But what about real trampolines? The key physics lie with biomechanics. (My point in the previous post, in fewer words than what follows.)

First, let us understand why we cannot rebound on concrete floor. When we are landing on concrete, our muscular and skeletal structures must absorb the shock, so as to prevent injury. Once absorbed, these two biomechanical systems give very little back. Hence no bounce on concrete.

Why then can we rebound on a trampoline? This is because the trampoline absorbs the shock very slowly that our muscular and skeletal system need not participate. Thus, most of the energy is absorbed by the trampoline, and then returned in the rebound.

Conclusion: the concrete floor does not exhibit "trampoline effect" not because it cannot, but because our body cannot endure an elastic collision with concrete and remain intact.

that's brilliant!! but in a more...simple way of stating all that, unless i'm mistaken, it's this. while strings with less tension do stretch more, you have to remember, no energy transfer is 100% efficient, and the elastic strings will absorb more of the energy being transfered compared to tighter strings, where the contact with the shuttle is a lot shorter, so less energy is lost in the elastic movement of the strings. it's like getting a weak, loose rubber band and shooting a paper dart with it, compared to getting a really tough, less stretchy rubber band and firing the same dart. we all know which will be better right? after all, we've all done it before :D :D

the reason many think that loose strings are better is because it's easier to control and harder to do a bad shot, but once you have this control, tighter strings are much better. why do you think Fu Haifeng strings his racquet at 30lb+, if he wanted more power, he'd go for 18lb or something

[drowsysmurf]

itz all a bell curve, too tight and us till lose the power as normal players... professionals like fu haifeng can string at 30lbs but the force of his arms can push the racket to have a slightly higher contact time than if I were to use that racket. There is still an equilibrium somewhere just different for different ppl because we do not apply the same force. last but not least fu haifeng is LEFT HANDED!!!!!!!!!! CREATES A DIFFERENCE SPIN ALLOWING HIS SMASH TO BE FASTER...

[Shifty]

itz all a bell curve, too tight and us till lose the power as normal players... professionals like fu haifeng can string at 30lbs but the force of his arms can push the racket to have a slightly higher contact time than if I were to use that racket. There is still an equilibrium somewhere just different for different ppl because we do not apply the same force. last but not least fu haifeng is LEFT HANDED!!!!!!!!!! CREATES A DIFFERENCE SPIN ALLOWING HIS SMASH TO BE FASTER...

well, it was an example, and i know none of us will ever string it at 30lb but it's to get the general idea that loose strings don't mean power. also, you are wrong about the left-hand bit. if you think about it, the contact is with the cork, which means regardless of handedness, it's the same contact silly. what you're talking about is a slice, when the contact is with the feathers, in which a left-hander does create a faster spin, but NOT A SMASH. a smash is contacted with the base of the cork, so it doesn't matter at all.

[drowsysmurf]

the point of contact also comes from the left and hits the cork at a different angle. this would spin the bird slightly differently which creates a slight differents in speed. unless the smash is really really flat on which typically is close but not exactly.
i string my racket at 30lbs. it feels great but itz bg 65 strings so it goes down to about 27 or 28 lbs after a few hits.

[Shifty]

the point of contact also comes from the left and hits the cork at a different angle. this would spin the bird slightly differently which creates a slight differents in speed. unless the smash is really really flat on which typically is close but not exactly.
i string my racket at 30lbs. it feels great but itz bg 65 strings so it goes down to about 27 or 28 lbs after a few hits.

umm....shouldn't the point of contact for striking a shuttle be square? that's what they teach you. if you're saying the POC comes from the left, then theoritically, right handers hit harder from the backhand corner because the swing is left to right whereas in the forehand corner, it changes. the POC changes as you move around. a normal shot has to be hit square, otherwise it wouldn't go straight would it? if it's an angled shot, the POC changes as you hit it towards the direction you want.

[CoolDoo6]

To hit harder, there's no need to use the left hand, or the right hand, or indeed do a loopy-loop with the racket prior to the hitting. All one needs is a heavier, or very fast, or heavier and fast racket. This is fundamental physics the army of Newton fans here will no doubt understand.

[drowsysmurf]

oh whatever you all want to think... i quit this convo... >=/ goodluck on ur backhand if u can use it like ur forehand... and yeah... newton... works for ideal case and is the basis knowledge but when you add a bunch of factors to newtons theory, things become more complicated not soo simple like those basic physics class u take..

[Shifty]

To hit harder, there's no need to use the left hand, or the right hand, or indeed do a loopy-loop with the racket prior to the hitting. All one needs is a heavier, or very fast, or heavier and fast racket. This is fundamental physics the army of Newton fans here will no doubt understand.

are you sure about no build up? much of the speed in any top badminton player comes from the abdominal and core muscles. Lin Dan can do 93 situps in a minute, which is one of the reasons he can blast it harder than Bao, because his hip and body rotation adds so much more power. if the heavy racquet is your conception, why not play badders with a tennis racquet. the heavy racquet you get, the less and less swing you generate, which means less speed. why doesn't Fu Haifeng use a Carbonex 21 or older, heavier racquet? because he can't generate the swing speed. head heavy racquets were made so it could generate more speed without compromising the weight. at 145g, it seems a rather heavy racquet don't you think? why can Fu Haifeng hit it at 332 km/h with a 85g racquet?? Newton only applies to badminton to a certain extent.

[Shifty]

oh whatever you all want to think... i quit this convo... >=/ goodluck on ur backhand if u can use it like ur forehand... and yeah... newton... works for ideal case and is the basis knowledge but when you add a bunch of factors to newtons theory, things become more complicated not soo simple like those basic physics class u take..

sorry if i offended you or anything, it's just what i think. i might be wrong ya know.

[jerby]

To hit harder, there's no need to use the left hand, or the right hand, or indeed do a loopy-loop with the racket prior to the hitting. All one needs is a heavier, or very fast, or heavier and fast racket. This is fundamental physics the army of Newton fans here will no doubt understand.
yeah, proper body rotation is soo 2006:p

just like other myths perpetuated by coaches..like footwork, or gripping...

[Shifty]

to talk about the loose and tight strings, which gives the better performance, i will use physics, as everyone seems to use physics to solve problems :D i'm sure CoolDoo knows the formula Ft=mv in which m is mass(of shuttle) v is shuttle velocity, t is time on string bed and F is force with which the shuttle is sent back. if mv is constant, then lets look F and t. for a loose string bed, say the contact time was 0.5s, and a tight string bed is 0.1s then

to keep mv constant, at say, 5, then

(1) Fx0.5=5 F then equals 10.
(2) Fx0.1=5 then F equals 50

as can be seen, a shorter contact therefore results in 5 fold power increase of the return shot. of course, the times will vary, but there can be seen the physics side of it, a longer contact time means less force is put into the return shot, whilst short contact means more power, if all other variables are kept the same.

there, a proven physics equation (hopefully correct :p)

as for CoolDoo's insistence that a heavy racquet is better, consider this, CoolDoo, you are saying that a heavier racquet will produce more power, i agree, but only when other variables such as swing speed remain constant. and let's face it, no one can generate their fastest swing speed with a heavier racquet compared to a lighter one. the heavier the racquet gets, the slow one swings, which has a big impact on speed on shot. so while in physics, it works, not in the real world, where swing speed changes with the weight of the racquet

[franxon]

To hit harder, there's no need to use the left hand, or the right hand, or indeed do a loopy-loop with the racket prior to the hitting. All one needs is a heavier, or very fast, or heavier and fast racket. This is fundamental physics the army of Newton fans here will no doubt understand. i've said it before, a racket does not have a speed. so you can't find a "fast" or "slow" racket. i have also mistakenly said that a racket does not have an MOI, I was wrong on that. a racket does have its MOI but it was too late to edit my words 15 mins after i posted it. :-D

here, we are talking about the accerlation in a rotation, so when we say heavy or light, what we really mean is the MOI, not the mass of the racket. so, there's no point to say that you put some grams on the handle to make the racket very heavy, and yet you still can swing it fast and that way you have a heavier yet "faster" racket. it's obviously false. the reason why we care about MOI and speed is because we want MOMENTUM, a hundred grams in the handle do not do one much good on momentum.

and, there's no way for me to believe that you put some grams on the frame and now you can swing the racket faster.

so once again, let me make my point clear: more MOI ("heavier"), less accerlation ("slower); less MOI (lighter), more accerlation ("faster"). there is no such thing as more MOI and more accerlation, i.e. "heavier" and "faster".

[Shifty]

and, there's no way for me to believe that you put some grams on the frame and now you can swing the racket faster.


dead on correct. a heavier racquet should mean less swing speed, so the effect of mass of racquet is cancelled out by a slower swing. also, it tires you out quicker :D why else are they making lighter and lighter racquets? why don't you go back to the good old wooden racquets, with a 14.5lb tension string and tell us how fast your smash is then ;)

[GunBlade008]

CoolDoo6 is desperate for attention haha

[CoolDoo6]

so once again, let me make my point clear: more MOI ("heavier"), less accerlation ("slower); less MOI (lighter), more accerlation ("faster"). there is no such thing as more MOI and more accerlation, i.e. "heavier" and "faster".

Yes, well observed, and your point couldn't be clearer. I wish I could make a point as clear as yours. Hence my rackets have low MOI. Look at my table again. Use reading glasses if necessary.

[Shifty]

Heavier racquets do not generate more velocity than light racquets. CoolDoo6, in your table, Your logic suggests that if there were a racquet so headlight, that all the weight distribution would be concentrated near the handle. Which would make the racquet head have 0 weight. Mass is needed to generate force, if the weight is 0, there would be no repulsion, no velocity and no shot.

The weight that you hold near the handle would still be a pain to move around, it is as if you are taping a dumbell to a racquet head, holding the dumbell and trying to hit a shuttle. Producing more power with a 120g racquet is overexaggerated, you also forgot to include the ability of one's swing power to generate power. Yes, in some terms, heavier racquets do produce more power, but to an extent, nothing past 90g. After that, one's ability to generate enough swing power would greatly be affected in a negative way. Thus making the "potential power" of a heavy head light racquet useless (Unless you change the laws of physics).

Though we do not have Sir Issac Newton here with us, I think everyone on BC can disregard your post/opinions regarding this matter because until you have concrete proof through a means of a speed radar gun and video, there is no proof at all that either Fu Haifeng, you, nor anyone else can produce more angular velocity with a 120g racquet than with say, a 90g racquet.

yeah, that's a good point. CoolDoo, you seem to be ignoring the fact that you can NEVER swing a 90g racquet as fast as a 120g racquet, the swing velocity will be so much less it counter's the weight advantage. for your table, it's taking into account you are swinging with the SAME FORCE, which is totally unrealistic. let's face it, if we can swing a 120g racquet at 98 miles per hour, HOW THE HELL can we then swing a lighter racquet at a LOWER speed??? you are also treating the impact velocity the same, at 100m/s which is totally unrealistic. i ask you, how can we swing a 90g racquet and a 120g racquet the same?

if you think it's about the weight, play badders wit a tennis racquet and see how much power you get out of that huh? and why would you think too much power is bad?

if you want a real life, World Champion example, ask Fu Haifeng why he doesn't play with a metal racquet. ask every pro player why they don't play with wooden racquets to get more power??

[GunBlade008]

Exactly my point, CoolDoo6 uses only the logic he chooses so that he may "seem" correct in our eyes, but then he excludes many crutial factors that greatly determine the outcome.

[Loppy]

Yes, well observed, and your point couldn't be clearer. I wish I could make a point as clear as yours. Hence my rackets have low MOI. Look at my table again. Use reading glasses if necessary.

More MOI also means more momentum (angular momentum), so a head heavy racket like the AT700 will have larger MOI than a light-headed racket of similar weight and allows the AT700 to smash harder. I'll try to explain the basics of momentum for everyone, not many people understand how angular momentum works.

The total momentum of a racket is actually the angular momentum + linear momentum. so Total momentum = (MOI * angular vel) + (mass * linear vel), and this is conserved before and after you hit the shuttle. Therefore lowering the Moment Of Inertia will NOT simply increase your smash power, it's a lot more complicated than that. Therefore claims that a light-headed 120kg racket can smash harder than a heavy-headed 90kg racket is unrealistic to say the least.

[Shifty]

More MOI also means more momentum (angular momentum), so a head heavy racket like the AT700 will have larger MOI than a light-headed racket of similar weight and allows the AT700 to smash harder. I'll try to explain the basics of momentum for everyone, not many people understand how angular momentum works.

The total momentum of a racket is actually the angular momentum + linear momentum. so Total momentum = (MOI * angular vel) + (mass * linear vel), and this is conserved before and after you hit the shuttle. Therefore lowering the Moment Of Inertia will NOT simply increase your smash power, it's a lot more complicated than that. Therefore claims that a light-headed 120kg racket can smash harder than a heavy-headed 90kg racket is unrealistic to say the least.

why else does LD and most top attack players choose a head heavy 90g racquet? totally agree wit you

[CoolDoo6]

The total momentum of a racket is actually the angular momentum + linear momentum. so Total momentum = (MOI * angular vel) + (mass * linear vel), and this is conserved before and after you hit the shuttle. Therefore lowering the Moment Of Inertia will NOT simply increase your smash power, it's a lot more complicated than that. Therefore claims that a light-headed 120kg racket can smash harder than a heavy-headed 90kg racket is unrealistic to say the least.

Since it still isn't clear to you what racket power is, let me recap:

** When the shuttle is made to fly fast by a racket, the racket is considered powerful. The faster, the more powerful **

Now, what is the minimum speed of shuttle after an imapct with the racket, assuming no mis-hitting ? The shuttle must fly at least a little bit faster than the racket head, or the shuttle would never leave the racket. In reality the shuttle would fly at the racket head speed plus X. Where X is the additional velocity producted by the effects of string and racket flex. Lets keep things simple and assume we have horrible stiffness in string and flex and neither produce any repulsion at all thereby giving X=0. With this racket, the only determining factor for power is how fast the racket head is after shuttle impact. From this we can deduce the general rule:

** Faster the racket head speed is after impacting the shuttle, the more powerful the racket is. **

It can be accepted that a heavy low-MOI racket would have greater angular velocity than a high MOI racket from the same torque.

It can also be accepted that a heavy racket would have lower linear velocity from the same force.

Because the racket motion is disproportionate in its angular travel compared to it's linear travel (compare how much disance the racket head covers to the distance covered by the racket handle), the benefit of greater angular velocity, by virtual of it being used more often, out-weights the drawbacks of lower linear velocity. The result is a surplus of overall racket velocity from the heavy low MOI racket. This produces a faster racket head speed after an impact.

[eggroll]

I must say I've been following this thread for the chuckle factor because so many people get drawn in by the off the wall comments but there are a few things that I would like to say.

Before I started playing badminton I was a fairly good squash player and one night I stopped by the badminton courts after playing squash and started hitting it with some friends who were doing drills. When I got the timing right, say once in 6 tries, the smash with a squash raquet was amazing. Pretty much unreturnable. The drawback though is that trying to drive was useless and there was no touch. I also couldn't have lasted a game with the weight.

The game of badminton is not just about power. The gain by a top player using a heavier raquet would be more than offset by the reduced feel and the slower reaction on defense. I believe a company could make a raquet that would be a pure smash weapon but for the one time in ten you would be able to time it right and get to use the available power it would feel good for one point but you would be shaking hands early.

Like anything it's about balance and I liken this disussion to long drive competitions in golf where the swings and equipment are geared towards one thing. I personally have played with a guy who has won world chamionships in long drive and playing 18 holes I can take him. When he competes in long drive he uses a club that is longer in length, different swingweight, and the head is made just for that one swing, one time on the contact point on the one spot on the face that will launch it 400 yards. Miss that spot and it's 350 towards the sidelines. He doesn't use his long drive driver to play with. Too many shots in the trees. If you had a fastest smash competition then you could find that one beast of a raquet to do that with. Until then you will have to return the other guys smash, drops, and clears. The game is so fast now compared to 15 years ago you couldn't compete with a smash only raquet.

Perhaps I'll get a proper radar gun next fall and see if we can put up a prize for the hardest smash here in Calgary. Anybody interested?

[franxon]

Yes, well observed, and your point couldn't be clearer. I wish I could make a point as clear as yours. Hence my rackets have low MOI. Look at my table again. Use reading glasses if necessary.what do you suggest me look for in your table? your table and my points can't be both true. besides, your table displays numbers of your calculation, not of your measurements. if they were indeed numbers from measurements, then reading glasses are definitely necessary for me because i wouldn't believe my eyes. i might even need someone else read them for me.

that's sarcastic, not really a good sense of humour. firstly Mr Newton didn't play badminton and now reading glasses. Neither was necessary in the discussion.

i can safely tell you your numbers are way off, as a result of the model your calculation was based on. i can give you at least 5 more parameters which one cannot afford to miss in one's model for a serious calculation like you were attempting to do.

[Shifty]

what do you suggest me look for in your table? your table and my points can't be both true. besides, your table displays numbers of your calculation, not of your measurements. if they were indeed numbers from measurements, then reading glasses are definitely necessary for me because i wouldn't believe my eyes. i might even need someone else read them for me.

that's sarcastic, not really a good sense of humour. firstly Mr Newton didn't play badminton and now reading glasses. Neither was necessary in the discussion.

i can safely tell you your numbers are way off, as a result of the model your calculation was based on. i can give you at least 5 more parameters which one cannot afford to miss in one's model for a serious calculation like you were attempting to do.

you ain't alone, i didn't believe them either. i think CoolDoo's fighting a one man battle here :D

[Shifty]

Since it still isn't clear to you what racket power is, let me recap:

** When the shuttle is made to fly fast by a racket, the racket is considered powerful. The faster, the more powerful **

Now, what is the minimum speed of shuttle after an imapct with the racket, assuming no mis-hitting ? The shuttle must fly at least a little bit faster than the racket head, or the shuttle would never leave the racket. In reality the shuttle would fly at the racket head speed plus X. Where X is the additional velocity producted by the effects of string and racket flex. Lets keep things simple and assume we have horrible stiffness in string and flex and neither produce any repulsion at all thereby giving X=0. With this racket, the only determining factor for power is how fast the racket head is after shuttle impact. From this we can deduce the general rule:

** Faster the racket head speed is after impacting the shuttle, the more powerful the racket is. **

It can be accepted that a heavy low-MOI racket would have greater angular velocity than a high MOI racket from the same torque.

It can also be accepted that a heavy racket would have lower linear velocity from the same force.

Because the racket motion is disproportionate in its angular travel compared to it's linear travel (compare how much disance the racket head covers to the distance covered by the racket handle), the benefit of greater angular velocity, by virtual of it being used more often, out-weights the drawbacks of lower linear velocity. The result is a surplus of overall racket velocity from the heavy low MOI racket. This produces a faster racket head speed after an impact.

problem is, can you swing the heavier racquet faster or just as fast as a lighter racquet? and keep it up for the whole game

[drowsysmurf]

i wasn't offended... i quit this convo because it is pointless. all the stats in here are focused on "constants" in rl, nothing is constant. ideal case doesn't apply... newton's law only applies so far, couple by many other LAWS AND EQUATIONS (some of what i do not know and some that i do). using statics, you can calculate you "ideal case" then using dynamics, you can pretty much calculate the whole motion. however... that would probably require a couple pieces of paper of calculation (front and back of the paper) if you really want to know... go take some courses in that field and find out. already gave you the name of the subject. STATICS AND DYNAMICS. goodluck... thread should be pretty much considered close unless you have done those calculations in which case, i would be really interested if you can post up pictures of them =) CHEERS! =D

[Shifty]

i wasn't offended... i quit this convo because it is pointless. all the stats in here are focused on "constants" in rl, nothing is constant. ideal case doesn't apply... newton's law only applies so far, couple by many other LAWS AND EQUATIONS (some of what i do not know and some that i do). using statics, you can calculate you "ideal case" then using dynamics, you can pretty much calculate the whole motion. however... that would probably require a couple pieces of paper of calculation (front and back of the paper) if you really want to know... go take some courses in that field and find out. already gave you the name of the subject. STATICS AND DYNAMICS. goodluck... thread should be pretty much considered close unless you have done those calculations in which case, i would be really interested if you can post up pictures of them =) CHEERS! =D

haha, i agree, there are too many constants, but then again, i'm just a simple person :D :D

[CoolDoo6]

what do you suggest me look for in your table?

Well, lets keep it simple. Both you and I agree low MOI is GOOD.

[franxon]

Well, lets keep it simple. Both you and I agree low MOI is GOOD. no, i never said that. quote it if you can find it.:D

[CoolDoo6]

no, i never said that. quote it if you can find it.:D

As you wish.

Presumably now you will tell me MORE ACCELERATION and FASTER are both BAD.



less MOI (lighter), more accerlation ("faster").

[jerby]

faster =/= good

higher MOI could be 'good' in a different way (nót faster, but different)

eitherway..hwo do you 'reduce' MOI by adding mass...no matter where you add it you're increasing it...perhaps a lot, perhaps just marginally..but always increasing..

[jerby]

I already know you'll say you're adding the weight to the handle... sorry for baiting..

But then..why not wear a sweatband? or maybe a wrist-weight..that'll surely boost the momentum!

[franxon]

As you wish.

Presumably now you will tell me MORE ACCELERATION and FASTER are both BAD.I will tell you something unpredicted by you: :D

perhaps my points are still not clear enough for you. less MOI, more accerlation. why is more accerlation necessarily good?;)

[CoolDoo6]

Played again with my heavy racket. When I wasn't warmed up, the racket felt heavy. But the heavy feel went away as soon as I was into a game. The power remained consistently good at the end of the night as I got more and more tired from all the running around. Although the racket produced no tire feel for my arm at all. Once again, the defense was top notch. The clearance power was excellent and under control. Very few shots were overshooting the base line. A few more sessions of observation and the racket could become my best mod yet. The BP was shifted by 5mm to 236 achieving the lowest MOI ever, and the highest racket head acceleration ever.

The 125g racket weight is at or very close to my upper limit of tollerance. I don't see this going any higher in the foreseeable future.

[franxon]

Played again with my heavy racket. When I wasn't warmed up, the racket felt heavy. But the heavy feel went away as soon as I was into a game. The power remained consistently good at the end of the night as I got more and more tired from all the running around. Although the racket produced no tire feel for my arm at all. Once again, the defense was top notch. The clearance power was excellent and under control. Very few shots were overshooting the base line. A few more sessions of observation and the racket could become my best mod yet. The BP was shifted by 5mm to 236 achieving the lowest MOI ever, and the highest racket head acceleration ever.

The 125g racket weight is at or very close to my upper limit of tollerance. I don't see this going any higher in the foreseeable future.that you have found the right place doesn't necessarily mean your map you used is not wrong.

besides, you claim you have found the right place, (so your map is correct). but have you really? how wonderful you can smash and defend with your new MOI-lowered-by-adding-weight-at-the-grip racket is very subjective.

LD or Taufik can't care less about momentum or MOI. they can find the right racket, string and tension without knowing all these junk. we *are* talking about junk, but there are still true junk and false junk. :D