Don't blame the rubber if you don't get enough spin.

[brokenball]

Assuming you can swing the paddle at 30 m/s ( base ball pitchers throw balls at 40 m/s ) then you divide that by the radius of the ball to get radians per second and then divide again by 2*PI to get revolutions per second. The number is about 239 revolutions per second and this is MUCH higher than what best players get but that is because I have assumed the ball is being perfectly brushed which isn't really possible. If one brushes the 30 degree point ( some call that 2 o'clock ) then the sin(30 deg)=0.5 so multiply the 239 by 0.5. The result is about 120 rev/sec which is realistic. That is lot of spin but most of us don't have the consistency be swinging at 30 m/s so if you swing at 20 m/s then you can achieve 80 rev/sec which is still pretty good..
I am assuming the rubber doesn't and extra spin from a spring effect. So if it is possible to get this much spin with just friction and no spring effect then why do so many people think they need spinnier rubbers? I think their technique sucks.

So is H3 national that spinny or is it the top players know how to spin the ball? I think the top players know how to spin the ball.

 

[Gozo Aruna]

We all know we sucks, however, our ego think otherwise...

 

[Zwill]

80 rev/sec is garbage and not pretty good.

 

[blahness]

Assuming you can swing the paddle at 30 m/s ( base ball pitchers throw balls at 40 m/s ) then you divide that by the radius of the ball to get radians per second and then divide again by 2*PI to get revolutions per second. The number is about 239 revolutions per second and this is MUCH higher than what best players get but that is because I have assumed the ball is being perfectly brushed which isn't really possible. If one brushes the 30 degree point ( some call that 2 o'clock ) then the sin(30 deg)=0.5 so multiply the 239 by 0.5. The result is about 120 rev/sec which is realistic. That is lot of spin but most of us don't have the consistency be swinging at 30 m/s so if you swing at 20 m/s then you can achieve 80 rev/sec which is still pretty good..
I am assuming the rubber doesn't and extra spin from a spring effect. So if it is possible to get this much spin with just friction and no spring effect then why do so many people think they need spinnier rubbers? I think their technique sucks.

So is H3 national that spinny or is it the top players know how to spin the ball? I think the top players know how to spin the ball.

You're assuming perfect transfer of kinetic energy to the ball which is close to impossible - that's ignoring a lot of friction losses during the collision, and assumes that coefficient of restitution=1. Other threads have shown these losses to be over 60% even with topline rubbers.

Furthermore, swinging a paddle at 40m/s is not trivial - it requires almost perfectly timed biomechanics and I reckon only professional pitchers get those kind of speeds. With table tennis, you're further limited by having to ensure the backswing is as small as possible to avoid getting jammed, and the constraints of having to land the ball on the table, which makes swinging that fast even harder. I think zeio shared some articles showing much lower swing speeds even from pro players.

 

[Der_Echte]

We can geek out over the equations used... but grip pressure is a factor difficult to measure and very important on the outcome.

Pretty much agree with BB for different reasons. YES, if you do not make good spin, it is your fault... BUT... it is correctable... a little easier than pulling elephant teeth.

 

[lodro]

Assuming you can swing the paddle at 30 m/s ( base ball pitchers throw balls at 40 m/s ) then you divide that by the radius of the ball to get radians per second and then divide again by 2*PI to get revolutions per second. The number is about 239 revolutions per second and this is MUCH higher than what best players get but that is because I have assumed the ball is being perfectly brushed which isn't really possible. If one brushes the 30 degree point ( some call that 2 o'clock ) then the sin(30 deg)=0.5 so multiply the 239 by 0.5. The result is about 120 rev/sec which is realistic. That is lot of spin but most of us don't have the consistency be swinging at 30 m/s so if you swing at 20 m/s then you can achieve 80 rev/sec which is still pretty good..
I am assuming the rubber doesn't and extra spin from a spring effect. So if it is possible to get this much spin with just friction and no spring effect then why do so many people think they need spinnier rubbers? I think their technique sucks.

So is H3 national that spinny or is it the top players know how to spin the ball? I think the top players know how to spin the ball.

Honestly BB, you know we all love you but half the way through your write-up I contemplated suicide 😂

 

[OldUser]

We all know we sucks, however, our ego think otherwise...

I’m quite sure you play music too right ? hahaha

 

[OldUser]

Honestly BB, you know we all love you but half the way through your write-up I contemplated suicide 😂

That’s exactly what I’m thinking when I want to impart spin with a 5 bucks walmart racket… my wrist and arm are both taking a rope and saying to me « is that REALLY what you want us to do ?»

 

[brokenball]

80 rev/sec is garbage and not pretty good.

The problem is that some of the energy can go into speed and some into spin. You can't have both at the max. There are trade offs. So how much spin do you need? Do you know? Have you ever done a simulation using differential equations with the formulas for drag and the Magnus effect?
have you ever used a high speed camera to see how much spin you generate like Palquay has?

 

[brokenball]

You're assuming perfect transfer of kinetic energy to the ball which is close to impossible

No i didn't.

- that's ignoring a lot of friction losses during the collision,

NO I I DIDN'T! There must be friction to create spin.

and assumes that coefficient of restitution=1.

I made it clear I assumed there was NO spring effect.

Other threads have shown these losses to be over 60% even with topline rubbers.

Are you talking about speed or energy. If you are talking about energy then you are probably close when talking about a flat hit. In that case 40% would be left. This equates to a normal COR of 0.63 or the rebound is 63% of the impact speed.

Furthermore, swinging a paddle at 40m/s is not trivial

Read more closely. I said 30 m/s which is about 70 MPH. Then I said reduce that to reflect your skill level.

- it requires almost perfectly timed biomechanics and I reckon only professional pitchers get those kind of speeds. With table tennis, you're further limited by having to ensure the backswing is as small as possible to avoid getting jammed, and the constraints of having to land the ball on the table, which makes swinging that fast even harder. I think zeio shared some articles showing much lower swing speeds even from pro players.

I said base ball pitchers can throw balls at 90 MPH or about 40 m/s and still have control. I assumed good TT players could manage 30 m/s
Just because you swing at 30 m/s doesn't mean the is flat hit at 30 m/s. As you start hitting the ball off center the more and more energy goes into spin and less into speed. If you flat hit, you better have a line of sight shot.

There is an optimal spin to speed ratio for each shot. I sometimes need to loop the ball from below the table. in this case more of the energy must go into spin because hitting the ball upwards too fast will cause the ball to go off the end of the table before it drops enough due to the Magnus effect.

 

[brokenball]

Honestly BB, you know we all love you but half the way through your write-up I contemplated suicide 😂

That is one way "to reduce the excess population." Ebeneezer Scrouge.
Seriously, don't you get a little annoyed at those that keep blaming their equipment instead of themselves?

Wait there's more!!!
I haven't proven there is an optimal spin to speed ratio yet. You will need to dust off your physic and calculus for that.
Wait till I explain why equipment doesn't have control. You will need to dust off your statistics for that one.
Or would you rather die in ignorance?

It really amazes me that TT forums never ask these questions. They just seem to be like a primitive tribe repeating myths to explain what they can't understand.

 

[brokenball]

This is whcle thread by Mr. Truth does not matter (aka brokenball) is bogus & complete waste of time.

Hurling lies again? What part is bogus? The formulas for converting angular velocity to angular rotation is fact. As you hit the ball closer to through the center then you start to lose spin but get more speed. What part of that do you disagree with?
Do you just like to be contrary?

If what TruthDoesnNotMatter says is true (pun intended) then we all should be using the same blade & same rubber spinny inverted both sides (backhand & forehand) of 1.7 mm thickness sponge as demanded by pickleball wannabe, hardbat & TTX nuts.

Where did I say that?

I am not at all saying technique is not important. It is of course very important. But for every human being there is a best blade & best forehand rubber & best backhand rubber. (For 90% of humans backhand is the weakside in all racket sport but it is lot more mission critical in tabletennis & forehand style is also probably very different from their backhand playing style for more humans than not but most amatuers delude themselves that they can be two winged loopers like Ma Long or Waldner etc) So a player (or his or her coach) should try to identify these 3 items as early as possible & fine tune them continuosly as a player evolves and then devolves due to aging etc (Jonyer switching to anti on his backhand ,though he was the early pinieer of the backhand loop itself & Stellan Bengtsson switching to short pips , both at the end of their careers are prime examples) and then try to work on the best technique for that chosen racket design. Of course perfection can only be strived for but never happens and that is where some reasonable EJing is essential by every player.

You make me laugh. There are probably many best FH and BH rubbers for each player because I doubt the player can tell them apart. People aren't calibrated machines that can measure microscopic differences. Coaches can be good at showing how but I haven't seen any that can say why.

 

[DukeGaGa]

ahh finally it happened, I have my lawn chair and a Diet Coke at hand: bb vs James. Round 1, fight.😎

 

[zeio]

You're assuming perfect transfer of kinetic energy to the ball which is close to impossible - that's ignoring a lot of friction losses during the collision, and assumes that coefficient of restitution=1. Other threads have shown these losses to be over 60% even with topline rubbers.

Furthermore, swinging a paddle at 40m/s is not trivial - it requires almost perfectly timed biomechanics and I reckon only professional pitchers get those kind of speeds. With table tennis, you're further limited by having to ensure the backswing is as small as possible to avoid getting jammed, and the constraints of having to land the ball on the table, which makes swinging that fast even harder. I think zeio shared some articles showing much lower swing speeds even from pro players.

"Linear speed of the racket = rotational frequency of the ball" has been a problematic assumption that somehow gets repeated without reservation as it ignores the effects due to moment of inertia (swingweight), which affects the kinetic/elastic (potential) energy, among others.

Experimental data collected from 6 Japanese women elite players, 5 righties and 1 lefty (one of them likely Ito from the silhouette), show that:
A power drive with an impact speed of 17.2±1.6 m/s results in ball spin of 181.4±55.2 rps;
A knuckle shot [no spin ball?] with an impact speed of 13.9±1.4 m/s results in ball spin of 104.6±39.9 rps.
Source: https://kaken.nii.ac.jp/ja/file/KAKENHI-PROJECT-16K01666/16K01666seika.pdf

 

[OldUser]

https://gifdb.com/gif/tina-and-amy-...s-night-meme-eku4qz1txlunmy1f.html?embed=true

 

[brokenball]

"Linear speed of the racket = rotational frequency of the ball" has been a problematic assumption that somehow gets repeated without reservation as it ignores the effects due to moment of inertia (swingweight), which affects the kinetic/elastic (potential) energy, among others.

Experimental data collected from 6 Japanese women elite players, 5 righties and 1 lefty (one of them likely Ito from the silhouette), show that:
A power drive with an impact speed of 17.2±1.6 m/s results in ball spin of 181.4±55.2 rps;

That wouldn't be a power drive. That would be a brushed ball. If there is no spring effect then the rotation rate is 17.6/(0.02*2*PI)=140 rps. You are assuming the spring effect adds another 40 rps. Effectively the top sheet must be stretched and snap back with an extra 40 rps * 2*PI*0.02*m= 5 m/s
Explain your assumptions. The paddle can't be purely brushing so some of the paddle impact is going through the ball, an eccentric impact. Eccentric is a word you have used before. The rest can go into spin but not all of the 17.6 m/s.

The rotational inertia of a TT ball is small and insignificant to the mass of the paddle and the person's hand and arm.
The rotational inertia of the ball is about 7.2x10^-7 m^2*kg. At 100 RPS the rotational energy is only 0.001421J which is small compared to the energy of the paddle. That isn't much.

 

[OldUser]

That wouldn't be a power drive. That would be a brushed ball. If there is no spring effect then the rotation rate is 17.6/(0.02*2*PI)=140 rps. You are assuming the spring effect adds another 40 rps. Effectively the top sheet must be stretched and snap back with an extra 40 rps * 2*PI*0.02*m= 5 m/s
Explain your assumptions. The paddle can't be purely brushing so some of the paddle impact is going through the ball, an eccentric impact. Eccentric is a word you have used before. The rest can go into spin but not all of the 17.6 m/s.

The rotational inertia of a TT ball is small and insignificant to the mass of the paddle and the person's hand and arm.
The rotational inertia of the ball is about 7.2x10^-7 m^2*kg. At 100 RPS the rotational energy is only 0.001421J which is small compared to the energy of the paddle. That isn't much.

 

[lodro]

That is one way "to reduce the excess population." Ebeneezer Scrouge.
Seriously, don't you get a little annoyed at those that keep blaming their equipment instead of themselves?

Wait there's more!!!
I haven't proven there is an optimal spin to speed ratio yet. You will need to dust off your physic and calculus for that.
Wait till I explain why equipment doesn't have control. You will need to dust off your statistics for that one.
Or would you rather die in ignorance?

It really amazes me that TT forums never ask these questions. They just seem to be like a primitive tribe repeating myths to explain what they can't understand.

It has become a very complicated world and it is not easy to be a genius anymore so : " YES"
when it comes to some technical aspect of this game I rather die ignorant.
Do you play the Saxophone or can you play a Shakuhachi flute ? 😁

 

[lodro]

ahh finally it happened, I have my lawn chair and a Diet Coke at hand: bb vs James. Round 1, fight.😎

Diet coke ??? Wait until the 14 round you will be needing the coke 😂

 

[OldUser]

Diet coke ??? Wait until the 14 round you will be needing the coke 😂

Well actually there have been some people high on coke that could elaborate funny concepts about noise bombs