paddle mass and speed

Krantz wrote: Isnt it that in the past heavier blades simply WERE faster - just because the construction of a "fast" blade required using heavier, thicker woods? Looks to me that this observation was indeed true by just coincidence and now become obsolete with the rise of light composite materials. edit: and that it is the “correlation does not imply causation” kind of problem.

Here is a thing that I saw in person. No guessing.

lawl at infinite loops one post *screencap*

let's assume no footwork;
also spinless still serves.
donkeys wonder I, dork,
ought to have some steel nerves.

He is right about the equation.  If that is all he is saying, then it is not particularly relevant to understanding how the weight of a blade affects the way people actually play table tennis.  To dismiss the effect that the blade has on the player, and in particular the weight of the blade, is to make the entire discussion utterly worthless.  I'm through with this thread.  

pnachtwey wrote: TheRobot99 wrote: It's only relating the simple physics. Not the more complex and unpredictable biophysics and neurophysiological terms that are being brought up again. And again and again and again.............. Finally, someone that understands. Everything else is a distraction.  This isn't a matter of disagreeing or agreeing with me.  I did not make this up.  It just the way it is.

First, I want to state up front that I very much enjoy and appreciate this post and the subsequent discussion (even if the participants are at times irritable).

Second, I haven't read every single post on this thread (but I have read many), so forgive me if I'm missing something.

And finally third, what I'm about to ask is motivated by sincere curiosity and is not meant to be disrespectful or unnecessarily provocative to any of the involved parties.

So, with my caveats out of the way...

I'm wondering if the intent of this post could be made clearer. The reason I ask is because, in spite of pnachtwey's frustrations, the post seems to lend itself quite readily to the "misunderstandings" or variations of interpretation that keep arising. Let me explain...

I understand that the above equations are accounting for very precise things and the results are just math--firm deductions describing the way things are--as it pertains solely to paddle mass and return speed of the ball. However, people keep bringing up other variables that are perhaps involved in return speed. I agree that these other variables are irrelevant to the equation modeling paddle mass and return speed, but these other variables are not irrelevant to the "bigger picture" of return speed, so to speak.

So, I'm not sure what the point is, other than to say this: "When taking into account an incomplete number of variables involved in the return speed of the ball, we can see that paddle mass makes little difference." That may be true, but I fail to see how it's saying anything terribly profound. In addition, it seems understandable that it inspires others to bring up other variables that this particular model does not take into account. I think that is perfectly reasonable.

To some people (including me, initially) it simply looks like pnachtwey is using a particular equation to substantiate the claim that lighter blades are better. This claim may or may not be true, but I certainly don't think this equation alone is indisputable evidence for such a claim. (And perhaps I'm wrong and that isn't pnachtwey's intent at all... which is why I'm asking for clarification of his intent.)

So yes, I can see why some of the physics dudes here keep face-palming when others bring up variables that this particular equation isn't meant to address.

However, I can also see why others insist on bringing up the non-addressed variables because those are important to the bigger picture if any interesting knowledge is to be discussed.

So after that long-winded spiel, I guess what I'm trying to ask--in the most respectful way possible--is this:

What's your point, pnachtwey?

I think the issue is, the only really sensible way to make a high performance light weight blade is with balsa and some composites and to people that are used to playing with "proper wood" that feels very alien. Also unless you are playing with a ALL speed balsa the blade is going to be stiff more things a lot of people aren't going to like. If you are going to use a balsa blade you start to relate blade feel not to how the blade bends or how it vibrates because with most balsa's they simply don't bend and don't vibrate. So you start to relate feel to how the immovable object of the blade transfers the ball feel into your hand.

Edited by nicefrog - 10/28/2010 at 1:50pm

A group of wealthy investors wanted to be able to predict the outcome of a horse race. So they hired a group of biologists, a group of statisticians, and a group of physicists. Each group was given a year to research the issue. After one year, the groups all reported to the investors. The biologists said that they could genetically engineer an unbeatable racehorse, but it would take 200 years and $100 billion. The statisticians reported next. They said that they could predict the outcome of any race, at a cost of $100 million per race, and they would only be right 10% of the time. Finally, the physicists reported that they could also predict the outcome of any race, and that their process was cheap and simple. The investors listened eagerly to this proposal. The head physicist reported, "We have made several simplifying assumptions. First, let each horse be a perfect rolling sphere . . ."

Kinetic balls.  Get over it....

Dont we have to keep in mind that rubbers dont give the same result on all the paddles? Sometimes a lighter one is harder/softer which results in more/less dwell, more/less catapult.

I've played with 100 gram blades before and 70 gram ones over the years but I've come to the conclusion the lighter blades are much superior, yes sure you don't get the "feeling" and they kick in your hand blocking, but to me after being used to them for so long now, that's all part of the charm.

Edited by nicefrog - 10/28/2010 at 9:18am

The only thing I have been trying to say is that the "feel" is something very real indeed, and it has a scientific basis too, one that I think is based on the physiology of motor control.  There is a reason why a 95 gram and an 80 g blade both feel awful to me and really do degrade my performance.  I certainly am not disputing the point made about COR.  I suspect it is one of the factors in table tennis, but I'm not sure how important it is.  When a player feels like they get a more powerful shot (using the term in a table tennis as opposed to a physics context) with a heavier blade, they may or may not actually impart more velocity and angular momentum to the ball.  But it may feel to the player like they are using less effort to do it (and this could be true even if they are actually expending more energy to accelerate a heavier blade to the same speed).  This feel could come from using a more optimal set of motor units (spinal motor neurons), and also to optimize proprioceptive control of the muscle, which also is affected by loading.  These are two of the reasons why the weight of the blade affects a player's timing of the shot and and affects one's ability to determine whether the ball hits in the optimal place on the blade at the right angle and with the right trajectory for the shot being attempted.  The body is making a really complicated calculation.  It is really unbelievable when you think about it what we are all able to do.

There is another point that has to be made.  Most of the players on this forum can sense a fast blade and a slow blade.   The differences between, say, a Schlager Carbon blade and a Petr Korbel both with 2.1 mm Tenergy 05 would feel like really big differences and would be agreed to in blind tests by nearly everyone on this forum.  And yet, the COR of these setups would probably not be very different if you actually measured it.  In fact, I can tell the difference between my two almost identical Viscaria blades with the same rubber!  Obviously they are made of wood so they are not identical.  To me, they feel ever so slightly different when I play with them, and this difference persists with repeated changes of rubbers.  I'm not quite sure what aspect of the blades I am perceiving.  They are about a gram different in weight.  It's probably not the weight that makes them feel a little different (or then again maybe that's all it is).  I am willing to bet that most of the players on this forum who have more than one blade of the same model have one that they prefer, or at least they are more used to.   Sensory-motor systems are pretty sensitively tuned things when people do something as difficult as playing table tennis or music!

The low influence of the paddle mass on the result of the formula
has to do  with the facts  that

1) the ball mass  is  small compared to the paddle mass
2) it is assumed that the paddle speed is the same for all paddle masses.

Point 1) is just a fact.
Concerning 2) ,   it might be  more realistic to assume that the impulse (product of speed and mass)
that a player can generate will be  constant, i.e.,  if the mass doubles, the speed will be only half.
(This is also only a rough approximation, since heavier weight will result in higher muscle activation etc.) Using constant paddle impulse p in the formula will give a paddle speed  v_p_0 =  p/m_p
(impulse divided my paddle mass)  in the formula, depending on the paddle mass m_p,
as opposed to   constant paddle speed.
The resulting curve will then show more  dependence on the paddle mass.

as

Edited by pnachtwey - 03/20/2012 at 4:21am