Dwell Time .....

[UpSideDownCarl]

Yeah. As I already stated, I don't think that shot should be legal. It is possible that while carrying the ball she rolled from FH to BH rubber like Freitas shows. The video is not clean enough for us to really see what happens. But it is likely there is more than one hit. I did see this before I posted it. However, I used it anyway because I have seen shots were people caught the ball totally cleanly and just held on to the ball on their racket as brokenball describes. And because, when you attacked langel you were not so nice about it. But what he said is actually possible. Not possible in a normal stroke, but possible. Even if it wasn't possible, being civil sometimes can go a long way.

And if I was able to find it, the guy who does catch the ball on his racket in some joke video and walk around the net, and then smash, I am pretty sure he kept catching the serve with no bounce. And again, this goes to brokenball's statement that he has seen someone catch the ball and in that instance dwell time for all intents and purposes, is infinite. And still the issue is the skill it takes to catch the ball. For sure when Freitas is catching the balls in the Grabbing and Punching part, the ball bounces. So he is not catching as cleanly as I am talking about.

But my main point was still that, in a normal stroke, with a skilled hand you can suspend dwell time a small fraction of a second longer.

And as long as you are okay with the idea that from 0.5 milliseconds to 3 milliseconds (and I think that may be close enough to accurate) is both a very short time, and from a different perspective it is a very large percentage. 600% is not a small amount from the standpoint of the percentage you have increased the dwell time. And that is all I was actually saying with my original premise. Given that a good stroke is often under a second long, it would be weird to expect dwell time to actually be the ball in contact with the blade face for the length of the entire stroke.

3 milliseconds is not enough time for the hand to really feel the actual contact. But you still can feel when you do extend dwell time. You feel vibrations from the wood, you feel/hear pitch, you feel the distortion, grab and rebound of the rubber conducted through the vibrations from the wood, and you feel the compression and rebound of the sponge through the same medium. And that feeling when you seem to feel the topsheet grab the ball and you hold the ball on the topsheet, it feels really good. To me, that makes playing worth it.

And blades like an old Butterfly Jonyer Hinoki (thin 5 ply) or an OSP Virtuoso or a Butterfly Petr Korbel actually help you learn to feel that and that could help you develop that skill.

So it is okay with me if people call that dwell time when it is really something slightly different.

 

[bircham boi]

Okay, so langel caught me in a bad mood and I was less than generous in my reply to him. That's not so hard to do these days, now I'm old and crotchety. Apologies to him and to anyone else offended thus far. Truth be told, I do get testy when people post stuff I consider to be dumb (again, a less than generous assessment).

This whole dwell time debate has been going on for years in numerous places, and it will keep going on long after I'm dead and in my grave. (I'm planning a hinoki coffin with mahogany handles, lined with red Ternergy 05, max thickness, which should use up any inheritance my kids might think they're getting.) I'm disappointed baal has stayed out of this conversation because, as you pointed out earlier, he can explain what's going on from a physiological perspective. brokenball accurately assesses dwell time as in the 1-3 millisecond range and baal explains why it's impossible for us to process that time as the shot is played.

Yes, we do "feel vibrations from the wood, you feel/hear pitch, you feel the distortion, grab and rebound of the rubber conducted through the vibrations from the wood, and you feel the compression and rebound of the sponge through the same medium". And I would never suggest otherwise. i have a number of blades made using the same core materials but with different outer plies and the differences between them are astonishingly different, in performance and in how they feel. But it's still impossible for me to tell the difference in dwell time. Difference in feeling, yes. Equally, I know that if I play a stroke differently with the same bat, it feels different. But it's not dwell time i'm feeling.

So... apologies for being a cranky, old git.

 

[UpSideDownCarl]

And we agree on all you said in this post.

There are a lot of terms used in TT that are not accurate but we still have an idea of what they mean. Terms like throw angle, dwell time, control.

I will stay away from the first two. But control, we know the control is from the player. Not from the equipment. We know that a classic smooth rubber like Mark V affords a different ease of use than LP or Tenergy.

Most LP rubbers make push-blocking or chopping easier (and therefore easier to control) than either Mark V or Tenergy. For low to mid-level players who don’t have good brush contact or racket speed, a rubber like Mark V would be easier to control than Tenergy. And it would also make offensive shots easier to control than LP. For a high level looper with good brush contact and good racket speed, using Tenergy would make it much easier to control the ball because the spin arcs the ball onto the table.

But somehow we have an idea what a person means when they say, “this rubber has good control,” rather than saying, “this rubber is easier to handle for a low level player who isn’t great at looping, chopping or chop blocking.”

[emoji2]

So I am okay with the term control in spite of the inaccuracy in the term. Same for dwell. I know what is meant. So I am not sure I need to debate the semantics.


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[splasher78]

Best grip: I will interpret that as the blade that grabs the ball best. I think that is what you mean. It is not what OP asked. But it may be a better question.

If that was the question the clear answer is an old, classic Joyner Hinoki or a Klampar Hinoki would grab the ball better than anything. These blades really grab the ball harder than anything else I have felt.

Hinoki grabs the ball amazingly. And those thin, flexy 5 ply Hinoki blades that were made in the 1980s and nobody makes today (not sexy enough), grab the ball better than anything ever.


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Hey Carl, great point. May you clarify what you mean when you say "grab the ball" are we still referring to dwell time/flex? Also I know EXACTLY what you mean in your previous post about seeing a good looper hold the ball on the rubber for that fraction of a second before the ball leaves the blade. Such a beautiful thing to witness. I've recently (3 months ago) learned how to loop the ball and and feel the spin I transmit to the ball by "brushing" it rather and straight hitting but i've never recorded myself so i don't know if I'm achieving that millisecond of a dwell but it kinda feels like it. Lastly, may you suggest any models of a "thin flexy 5 ply hinoki blade" in particular from the 80's that nobody makes today? I'd like to try one. Or any close alternative, My main blade is an Acoustic and I love it, already I am looking at a "training" blade Nittaku Latika in particular (from what i've read) sounds like it comes close to those hinoki blades you mention, even though i know it's not a hinoki. EJ'ng is starting again, i've relapsed. LOLOLOLOL.....

 

[UpSideDownCarl]

.....May you clarify what you mean when you say "grab the ball" are we still referring to dwell time/flex?......Lastly, may you suggest any models of a "thin flexy 5 ply hinoki blade" in particular from the 80's that nobody makes today? I'd like to try one. EJ'ng is starting again, i've relapsed. LOLOLOLOL.....

[emoji2] Grab and grip when talking about a blade is really like what I was describing with an inaccurate term like control above and what causes some people to see red when people talk about dwell time and throw angle. [emoji2] Just like dwell time, it is probably that you are just feeling more of the interaction between the blade and rubber as the rubber distorts and rebounds during contact.

We know the wood does not grab the ball. But somehow, when you play with one of those thin 5 ply Hinoki blades, it sure feels like that strange quality, soft, Hinoki wood allows the rubber to grab the ball more. So, that feeling when you are looping of feeling you really grabbed the ball hard....somehow Hinoki makes you feel a lot more of that. And on the slower, thinner Hinoki blades, man you really can generate A LOT more spin. A lot more.

I hope that is enough of an explanation because I don’t really think there is a good explanation for why softer, springy cedar type woods like Hinoki cause this. Or if there is, I don’t know enough of the physics to explain it. [emoji2] But it sure feels cool especially when looping.

I did list two blades like this earlier. I will simply list them again.

Butterfly Joyner H (Joyner Hinoki)* don’t get fooled by the Joyner Special where they made it thicker and faster to be sexier for today’s short attention span TT EJs who want an Off+++++++ sensation.

Butterfly Klampar H (again the H is for Hinoki)** I don’t think Klampar was famous enough for his blade to last as long as Joyner’s did.

That blade is not for sale. [emoji2]

One last note: players who make more direct contact and primarily drive or smash will absolutely hate the blades I just listed and think they feel slow, feelingless and not easy to control. Thin Hinoki blades are not so good for direct contact. Whereas, someone who really loops with full spin contact will think these blades are fast with great control and great spin. With drive contact these will feel like All or All- blades. With spin contact they will feel like Off speed or high Off- blades. Truly strange....but beautiful to those who can feel it.


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[UpSideDownCarl]

Isn't anybody going to do some rough math?
Years ago Baal did some "napkin" calculations that were pretty close given the assumptions.

brokenball, I don’t want your point to get lost. And since most of the discussion has really been about semantics, feeling and slight of hand which really isn’t science, can you spell out the real numbers? I am 100% confident you are better qualified to do that than anyone else on the forum.

Thank you.


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[splasher78]

[emoji2] Grab and grip when talking about a blade is really like what I was describing with an inaccurate term like control above and what causes some people to see red when people talk about dwell time and throw angle. [emoji2] Just like dwell time, it is probably that you are just feeling more of the interaction between the blade and rubber as the rubber distorts and rebounds during contact.

We know the wood does not grab the ball. But somehow, when you play with one of those thin 5 ply Hinoki blades, it sure feels like that strange quality, soft, Hinoki wood allows the rubber to grab the ball more. So, that feeling when you are looping of feeling you really grabbed the ball hard....somehow Hinoki makes you feel a lot more of that. And on the slower, thinner Hinoki blades, man you really can generate A LOT more spin. A lot more.

I hope that is enough of an explanation because I don’t really think there is a good explanation for why softer, springy cedar type woods like Hinoki cause this. Or if there is, I don’t know enough of the physics to explain it. [emoji2] But it sure feels cool especially when looping.

I did list two blades like this earlier. I will simply list them again.

Butterfly Joyner H (Joyner Hinoki)* don’t get fooled by the Joyner Special where they made it thicker and faster to be sexier for today’s short attention span TT EJs who want an Off+++++++ sensation.

Butterfly Klampar H (again the H is for Hinoki)** I don’t think Klampar was famous enough for his blade to last as long as Joyner’s did.

That blade is not for sale. [emoji2]

One last note: players who make more direct contact and primarily drive or smash will absolutely hate the blades I just listed and think they feel slow, feelingless and not easy to control. Thin Hinoki blades are not so good for direct contact. Whereas, someone who really loops with full spin contact will think these blades are fast with great control and great spin. With drive contact these will feel like All or All- blades. With spin contact they will feel like Off speed or high Off- blades. Truly strange....but beautiful to those who can feel it.


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Once again, thank you for your informative response and suggestions. I very much enjoy reading your posts! Lastly, have you or anyone here, heard of the Ross Leidy "Rapscallion" ??? "supposedly" a Looper's GRAIL blade. It's a custom blade but the price is in the same ballpark as my Acoustic, had I known of this blade first I probably would have gotten one. Anyway thanks again.

 

[langel]

[emoji2]

With drive contact these will feel like All or All- blades. With spin contact they will feel like Off speed or high Off- blades. Truly strange....but beautiful to those who can feel it.

Yes, fully agree.
I've mentioned in other threads too that a smash is a curse for Hinoki, and that a well spinned ball can be much much faster, glad you have the same feeling.

 

[Der_Echte]

At the club last nigh, there is an O60 gent ole timer who hangs out with the retired (and some young) crowd. He gives free group lessons and hits hours with them. He plays a close to table game and his FH rally stuff close to the table is better than mine. his quick reaction BH hit is as good as mine. He doesn't however, go for much spin on BH, which limits his possible responses, both at and a step away from table. Sometimes he drifts back a bit. This guy contributes a lot. Some clubs have one or three of this type. Some have zero.

Despite this limitation, he plays a pretty damn mean TT game, prolly 3 levels above average tt club level.

He knows I got a variety of BH topspins and finally got to some BH practice with me (after he had hit 4-5 hours all day with the energize bunny O60 crowd)

The first thing I tried to explain to him is the kind of loose muscles needed to accelerate the parts in sequence to make a whip. The next part was the kind of grip pressures at impact affecting the ball. Soft grip to absorb and control heavy incoming spin. Different degrees of firming up grip right at impact to give more pace and spin. A soft grip with acceleration to give a load of spin with a slower ball to give a high arcing shot dropping off a cliff late to land deep or real shallow.

Easy to explain the basic input/output relationships. Much more difficult to get the bio mechanics and grip right if one never did it... especially if they were a hard gripping all the way kinda guy all their tt life. Difficult to break that instinct.

So, I created a few easy drills to isolate the things that contribute to what is the bread and butter... initial loose grip throughout to get the FEEL of a soft impact, to get the feel of loose muscles, a very short stroke to eliminate power sapping and focus on impact with a soft grip... leading to later a small acceleration during the stroke with a soft grip... to get him to feel the ball and impact and see how that can so totally handle incoming spin.

This is a progressive approach not focused on the end result of a real spinny ball without the solid wood bang sound, but just to get a higher number of the kind of loose grip impact to get him to feel the ball.

I had him get close to the table and asked him to take the ball on BH right off the bounce with a loose grip, not worry about making a long stroke. Just a few inches with a soft grip take ball right off the bounce. Difficult with him as he likes to be 2 feet off the table and take the ball there with a hard grip. Eventually, I got him to take a step in and touch it off the bounce. He say what good happened, but too much instinct to be too far away from the bounce to do it instinctively.

So, I put that idea in the back of his head for later and had him do a similar thing, but away from table and far away from the bounce. He was more comfy doing that. I asked him to use 20-30 percent power with a loose grip. On BH, try to catch and throw the ball. Try to hold the ball a little longer on BH without trying hard, just loose grip, soft touch, not so much power vs incoming topspin. Try to let ball get into topsheet and sponge and throw it out with loose muscles NO TIGHT GRIP OR HARD IMPACT.

He get the feel of doing this more often than close to the table. On some shots, he was able to return my heavy topspin easily, generating a bit of his own. The heavy topspin return comes later. Important part is to get the impact right. Whether the ball goes over net or is real spinny is not the focus, just get the impact and feel right. Get the loose muscles and loose grip right. LATER, when feel and timing improve, use more grip pressure and acceleration, or loose grip and more acceleration to make a much spinnier ball. That comes later. Too hard to feel it and do it consistent the first session.

I say maybe 40-50% of the balls he got the impact right. Big deal 40%. The big deal was that when he got the impact right, he could feel it and he could see how easy he handled my topspin ball. The important part is now he understands the importance of being loose with both the muscles and grip. Later, he build more of the same impact and later, when feel and timing are better, go for more acceleration to get more spin and maybe pace. Later, experiment with increasing grip pressure right at impact to get a faster ball and more spin.

This is a progressive approach that does not result in any immediate results of a spinny or fast ball, but I believe it is one effective way to approach a strategic goal of playing a more flexible attacking BH.

 

[brokenball]

Baal did some "napkin" calculations many years ago on the MYTT forum that were pretty good.
Before that I had posted a similar calculation in "Anton's obscure question" thread. I posted a link to a view of Tacshow123 "catching" the ball and dropping it on the other side of the table. That is the video UpsideDownCarl was looking for. It is hard to find even if you know what you are looking for.

First we will make some crude estimates. With a little thought is is possible to estimate very closely. Too many think that because they can't solve a problem exactly that they shouldn't try solving the problem.

Assume the contact speed with the paddle is 10 m/s or 10mm/ms. That is the combined speed of the ball coming at the paddle and the paddle coming at the ball. The speed is measured relative to the paddle.

During the contact time the ball will slow down to 0 then speed up again in the opposite direction.

Lets assume the total contact time is 1 ms so the ball spends 0.5ms slowing down and 0.5ms speeding up.
How far will the ball go in 0.5 ms? During the time the ball is slowing down from 10mm/ms to 0mm/ms we will assume the ball decelerates at a constant rate. ( this is not right, the ball slows down slowly at first but slows down faster as the ball compresses the rubber, but we are making a crude estimate, look up Hooke's law ) Therefore the average speed during the 0.5ms of slow down time is 5mm/ms.

If the average speed is 5mm/s for 0.5ms, how far did the ball push into the paddle?
5mm/ms*0.5ms=2.5mm

Is this distance reasonable? I think we are in the ball park. I think the 2.5mm is a little too much. I think if I did some calculus and assumed the deceleration rate was not linear but was parabolic as described by Hooke's law, the deceleration distance would be shorter.
The ball will compress some so the center of mass of the ball may travel another 1-2mm closer to the paddle.
A 2mm rubber may compress 1mm. The blade may flex some but I doubt most paddles people buy will have visible or measureable flex but we know the blade flexes a little bit due the the sound.

This distance can be made shorter by decreasing the contact speed or by reducing the contact time.

A teaser for you problem solvers out there that like to strain your brain.
How can you tell how much of the ball makes contact with the top sheet?
How can you uses this to determine how far the ball's center of mass still moves after contact?
Are there any calculus wizards out there that can figure out the how the ball will decelerate if Hooke's law applies so that the deceleration rate is not constant.
How what is the peak force applied to the ball? Why do we care?

 

[Lightzy]

In most shots the ball hits the rubber at a steep angle so you can assume much greater penetration than you think

 

[zeio]

If you're talking about Dwell Time in the context of measured, phisics and factual manner, yes, there's no difference in measured dwell time between blades and rubbers. There's no difference in dwell time between pimple-in, pimple-out, long pimple, anti and hard bats according to the experiments conducted by Butterfly using 8000 FPS high speed camera. I think Baal mentioned in similar therad before but we can only distinguish the difference in dwell time if it's more than 10ms. There's abslutely no way we can tell the difference if it's less than 1/8000 second and it definitely does't show in 100/60FPS youtube video.

Other feedbacks such as rebound speed, rebound angle, vibration and sound gives us the percieved "dwell time".

Perception is important because telling somone to serve with backspin as if the "ball stays on the blade as long as possible" helps him/her spin more because brushing motion gives you longer percieved dwell time.

But saying that X bat or Y rubber gives you longer (measured) dwell time is simply wrong but Butterfly themselves use this term for marketing purpose, strange world!

The Butterfly experiment from 1980 only measured the dwell time for inverted rubber on what appears to be a Jpen and bare blade by shooting a no-spin ball head-on at 28m/s. There appears to be another one that they did for 4mm thick short-pips rubber on a Jpen and bare blade at 25m/s. Therefore, the number is only good for smashes.

There is a difference, albeit small, b/w inverted and non-inverted rubbers at different speeds below 10m/s, presumably head-on, in a study published in the coaching manual by JTTA in 1994.

I have highspeed footage done by none other than Butterfly for Tenergy and presumably Bryce in an oblique collision that shows the balls dig into the rubber at the same time, but leave at slightly different times. That's far more realistic and thus comparable to how we loop.

 

[brokenball]

I have highspeed footage

How high?

That's far more realistic and thus comparable to how we loop.

What where the dwell times at that speed? I bet the dwell time is much shorter than a millisecond so to tell the difference one would need to have about a 10K FPS camera at least.

In most shots the ball hits the rubber at a steep angle so you can assume much greater penetration than you think

If a ball makes contact at 10m/s and the angle is 45 degrees the normal speed will be about 7.07m/s so how does the ball penetrate farther?

No one has answered my questions.

 

[ttpshot]

The Butterfly experiment from 1980 only measured the dwell time for inverted rubber on what appears to be a Jpen and bare blade by shooting a no-spin ball head-on at 28m/s. There appears to be another one that they did for 4mm thick short-pips rubber on a Jpen and bare blade at 25m/s. Therefore, the number is only good for smashes.

There is a difference, albeit small, b/w inverted and non-inverted rubbers at different speeds below 10m/s, presumably head-on, in a study published in the coaching manual by JTTA in 1994.

I have highspeed footage done by none other than Butterfly for Tenergy and presumably Bryce in an oblique collision that shows the balls dig into the rubber at the same time, but leave at slightly different times. That's far more realistic and thus comparable to how we loop.

What were the numbers?

 

[Lightzy]

If a ball makes contact at 10m/s and the angle is 45 degrees the normal speed will be about 7.07m/s so how does the ball penetrate farther?

No one has answered my questions.

There is more sponge to compress at a 45 angle impact than there would be straight on, before hitting the blade and bringing the ball to a rapid stop. And storing some energy in the ball itself also through compression.

Relative speed is an important component of dwell (penetration) but angle (the volume of topsheet/sponge in the way of the ball) is also very important, and a fair few factors besides.

Also when we talk about dwell time, as tt players, we're thinking of it in terms of spin that can be imparted on the ball on its way out of the racket. Not about actual time, and never the penetration of the ball head on, which will only impact speed, and then possibly negatively so.
That's also why the compression of the ball can also be discounted, as it cannot really add to spin. Which is what i was agreeing to disagree about with hipnotic earlier.

 

[brokenball]

There is more sponge to compress at a 45 angle impact than there would be straight on, before hitting the blade and bringing the ball to a rapid stop. And storing some energy in the ball itself also through compression.

Yes, I could say the ball is traveling at about 14 m/s and hits the paddle at 45 degrees. The normal component would still be 10m/s the the sponge would still be the same thickness.
I am breaking the directions down into normal and tangential directions. It is good enough for a "napkin" calculation. OK?

Relative speed is an important component of dwell (penetration) but angle (the volume of topsheet/sponge in the way of the ball) is also very important, and a fair few factors besides.

So there is more rubber to compress if compressed at an angle. How does the affect the normal and tangential components?

Also when we talk about dwell time, as tt players, we're thinking of it in terms of spin that can be imparted on the ball on its way out of the racket. Not about actual time, and never the penetration of the ball head on, which will only impact speed, and then possibly negatively so.

Now you are making stuff up. Dwell time is the time the ball is in contact with the paddle.
The dwell or contact time is important because the impulse imparted on the ball is

Impulse = integral(force(t),t,0,dwell_time)

I think you should explain why penetration of the ball into the rubber isn't important. Why would it affect the speed.
It might depending on the sponge but I want you to explain.

That's also why the compression of the ball can also be discounted, as it cannot really add to spin. Which is what i was agreeing to disagree about with hipnotic earlier.

The deformation of the ball cannot be discounted. The center of mass is what is used for calculations.

When Marcos Freitas "catches" the ball, what the dwell time is potentially infinite. Notice that he tries to catch the ball at an angle then moves the paddle so the force is now normal to the paddle. This is stuff people do instinctively but have a hard time explaining or understanding. Basically Freitas is trying to minimize the deceleration force.

What are the necessary conditions for a ball to maintain contact with the paddle?

Why do you want a long dwell time anyway? No one has answered that one.

I see no one has answered my questions above.

 

[Suga D]

Best grip: I will interpret that as the blade that grabs the ball best. I think that is what you mean. It is not what OP asked. But it may be a better question.

If that was the question the clear answer is an old, classic Joyner Hinoki or a Klampar Hinoki would grab the ball better than anything. These blades really grab the ball harder than anything else I have felt.

Hinoki grabs the ball amazingly. And those thin, flexy 5 ply Hinoki blades that were made in the 1980s and nobody makes today (not sexy enough), grab the ball better than anything ever.


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This here.
+1.
Thanks Carl.
[Emoji106]
Some wood types seem to be able to increase the time the ball sits or rather dwells on the racket more than other wood types.

When i changed from my stiff Waldner Dotec Carbon to an old flexy Nittaku 3+2 Hinoki Carbon blade but using the same rubber setup (to that time it was Spinart on the fh and t05 on the bh) the dwell time felt notably longer which made it much easier to impart rotation to the ball even when in reality it just was the fraction of a second.
But not only that, the trajectory, the flight curve, was higher and more bent.

This feeling was only topped by an old Nittaku 3ply allwood Hinoki blade that provided an even more extended dwell and allowed me to compensate a bit of the loss of rotation due to the 40+ p-ball.
Also the carbon must have shortened the dwell compared to the 3ply allwood. Once more the trajectory (the throw angle) was higher plus the carbon has numbed down the lovely feeling that the Hinoki provides. On the allwood Hinoki i could feel much better when i hit the ball in the zone (the sweet spot) and when i hit it rather edgy.
Now with that 3ply All wood Hinoki i slowly started feeling that what old experts call the Hinoki stickyness. It almost felt like catching the ball and throwing it back. The post after my first session with that blade must still be somewhere in the depths of this forum.

Just lately i received 3 handcrafted customized Hinoki allwood blades.
The 3ply has the strongest flex and feelingwise the longest dwell of them.
The 5ply feels better when taking a step away from the table. Powerlooping by hitting more through the sponge just feels a little easier than with the 3ply.
The 7ply is the stiffest and at first felt a little awkward after being used to a flexy 3ply. It seems to provide more speed when looping from the back and even from 2 steps behind felt powerful and dangerous.
Compared to the Dotec even not so thinly brushed loops were spinnier and kicking off stronger after bouncing with the 7ply Hinoki.
One can tell i really love these blades even though the old Hinoki blades feel a bit more direct.

Hard to believe that the feeling of the handcrafted blades will even get better when more of the wood's natural moisture has evaporated over the years.

And even though Hinoki is often mentioned to be the spinners ambrosia, i've once met a guy with single ply Hinoki and he could brushloop quite strongly but also powerloop and flat hit some balls like i've never seen before.
One day i'll definitely try out a single ply Hinoki too....

[Emoji2]

 

[Lightzy]

.....
The deformation of the ball cannot be discounted. The center of mass is what is used for calculations.

When Marcos Freitas "catches" the ball, what the dwell time is potentially infinite. Notice that he tries to catch the ball at an angle then moves the paddle so the force is now normal to the paddle. This is stuff people do instinctively but have a hard time explaining or understanding. Basically Freitas is trying to minimize the deceleration force.

What are the necessary conditions for a ball to maintain contact with the paddle?

Why do you want a long dwell time anyway? No one has answered that one.

I see no one has answered my questions above.

I'm making stuff up? rofl. That's what I'm saying, that your definition of dwell time isn't the one anyone cares about, which is why nobody answers your questions. I can just as well say that your definition is made up. Which is to say, it is as good a definition as any, but it's not what people actually mean when they talk about dwell time, and so it's a bit irrelevant.


The 'time' thing doesn't matter. When a TT player talks about dwell time they're talking about how much they feel the ball going in the rubber and how much spin they can then generate.
Nobody talks about 'dwell time' in the context of flat smashes.
When people say dwell time they mean ball penetration, whether they understand it or not.

Therefore the deformation of the ball doesn't matter so much because it plays no part in the balls penetration into the rubber. Thus, again, it doesn't add to your ability to spin it.

The penetration of the ball into the rubber is of course important.That's the only thing that's important. I'm not sure why you're asking me to disprove that claim.




That said, for all practical purposes, to get the best dwell/spin you have to hold the racket firmly so that the ball penetrates 'evenly' without you allowing your racket to be pushed back by the impact, and to try to make the ball go through as much rubber as possible (so as closed an angle as possible)

 

[brokenball]

I'm making stuff up? rofl. That's what I'm saying, that your definition of dwell time isn't the one anyone cares about, which is why nobody answers your questions.
I can just as well say that your definition is made up. Which is to say, it is as good a definition as any,

It is the only one that can be used for calculations or simulations. Why do you think Butterfly would bother to take high speed videos to compare rubbers? I am assuming Zeio has these videos.

but it's not what people actually mean when they talk about dwell time, and so it's a bit irrelevant.

You are assuming the everyone thinks like you.
You assume that no one really wants to know what happens during contact.
You assume too much.
Without facts people will keep talking about dwell time for years to come. There have been high speed videos posted that prove that the dwell time is short. No one seems to remember those videos so soon they start making up their own myths and fairy tales.
People talk about having longer dwell time is better, why?

The 'time' thing doesn't matter. When a TT player talks about dwell time they're talking about how much they feel the ball going in the rubber and how much spin they can then generate.

This point was discussed on MYTT years ago. What you feel doesn't matter to the physics of that is happening during contact. How can a blade or rubber company ever hope to optimize feel. It is a personal preference so they make many paddles and rubbers but the same laws of physics apply to all of them.

Nobody talks about 'dwell time' in the context of flat smashes.
When people say dwell time they mean ball penetration, whether they understand it or not.

You are the type of troll that asks "How does the moon affect the flight of the ball, it affects the tides".
I said it was what Baal called a "napkin" calculation that will be close enough. As far as real strokes I only need to break up into normal and tangential components but if you can't or won't understand the simple normal example there is no point in making things more complicated.

Therefore the deformation of the ball doesn't matter so much because it plays no part in the balls penetration into the rubber. Thus, again, it doesn't add to your ability to spin it.

Yes it does. The center of mass is important for calculations. The stopping distance includes deformation of the ball, rubber and blade.

The penetration of the ball into the rubber is of course important.That's the only thing that's important. I'm not sure why you're asking me to disprove that claim.

What about the flex of the paddle?
I am not asking you to disprove any claim. It is apparent you can't or won't do the math.

That said, for all practical purposes, to get the best dwell/spin you have to hold the racket firmly so that the ball penetrates 'evenly' without you allowing your racket to be pushed back by the impact, and to try to make the ball go through as much rubber as possible (so as closed an angle as possible)

This is just an opinion until proven.
Unless the paddle is still I really doubt the paddle is ever pushed back. It is one of those conservation of momentum things.

Someone needs to answer some of my questions or there will be no more questions. UpSideDownCarl seemed want me to continue but I see no point now. The whole topic of dwell time will come up year after year after year with no answers. I don't care. I have the high speed videos. I can do the math and physics. I know and I don't dwell on it.

 

[Der_Echte]

Somewhere, in a dark cellar septic tank... although near the end of the week punishment of being trapped in the smelly darkness with large London Sewer Rat by falling for the old trick baited with the fake pile of National version H3 rubbers placed right over the trap door... the Goon Squad momentarily gets TTD on their smart phones and are ROFLOL at this thread... and not caring at all how much crap they just got all over their pristine 5th Avenue clothes.