but wait.....federer's wrist was so stable.....

[leon]

Burner, I think the distortion is even more than you think because no way did that handle twist in his hand.

Kind of looks like it did to me, if you look at the grip tape once the ball is gone.

Some things to think about:

Tennis ball impact duration is approx 10 times that of a golf ball
Tennis ball is a bit heavier (approx 20%) than a golf ball
Tennis racket is likely much stiffer in torsion than a golf shaft (I don't have numbers, but much larger "diameter" and thicker wall if I recall - have seen both being made)
Racket handle much shorter than club shaft, so higher bending stiffness too
You can hit a tennis ball a LOT further away from the centre of mass

Does this tell you anything?

 

[JonWil]

Kind of looks like it did to me, if you look at the grip tape once the ball is gone.

Some things to think about:

Tennis ball impact duration is approx 10 times that of a golf ball
Tennis ball is a bit heavier (approx 20%) than a golf ball
Tennis racket is likely much stiffer in torsion than a golf shaft (I don't have numbers, but much larger "diameter" and thicker wall if I recall - have seen both being made)
Racket handle much shorter than club shaft, so higher bending stiffness too
You can hit a tennis ball a LOT further away from the centre of mass

Does this tell you anything?

Actually, what you are seeing as a change in position of the grip tape is reflective of the degree of pronation he is using for the control of the shot he 'wanted' to hit. He was late to a ball that got down on him before he could stick it.

 

[Keefer]

Have no idea what the debate on or what "rate of closure" means. What I find interesting in the video is how the racket face is vertical when the ball comes into contact with the ball and how he is able to close it (de-loft it) and put top spin on the ball when it leaves the racket.

So the question would be is it possible to put a different spin on the ball by manipulating the club head with your hands after the golf ball comes into contact with the clubhead as Federer clearly does in this video with a tennis ball?

I realize if top spin were put on a golf ball like Federer's tennis ball the golf ball would not be in the air for very long. Still Federer is able to change the spin of the tennis ball while it's still in contact with the racket. I believe I've seen where it's said that once the golf ball is in contact with the clubface it's too late to alter spin / direction.

 

[ParHunter]

Have no idea what the debate on or what "rate of closure" means. What I find interesting in the video is how the racket face is vertical when the ball comes into contact with the ball and how he is able to close it (de-loft it) and put top spin on the ball when it leaves the racket.

So the question would be is it possible to put a different spin on the ball by manipulating the club head with your hands after the golf ball comes into contact with the clubhead as Federer clearly does in this video with a tennis ball?

I realize if top spin were put on a golf ball like Federer's tennis ball the golf ball would not be in the air for very long. Still Federer is able to change the spin of the tennis ball while it's still in contact with the racket. I believe I've seen where it's said that once the golf ball is in contact with the clubface it's too late to alter spin / direction.

He (Roger Federer) isn't delofting the racket, the ball hits the racket off-centre, the delofting happens because of that. Or do you think Federer deformed the racket on impact as well? Have a close look and you will see that the racket is deforming at impact. If the ball can deform the racket at impact, don't you think it can twist the racket as well?

I think the only person who could deform the racket at impact would be Uri Geller

 

[leon]

Actually, what you are seeing as a change in position of the grip tape is reflective of the degree of pronation he is using for the control of the shot he 'wanted' to hit. He was late to a ball that got down on him before he could stick it.

Unless the camera is really off, I don't think his wrist moves any where near as much as the racket. Also, I'm not sure how much top players have the intent of rotating the racket through impact to generate spin. I thought it was more down to angle and path (sound familiar?) My brother in law is a tennis coach, so if I get chance I'll ask him.

 

[mgranato]

Have no idea what the debate on or what "rate of closure" means. What I find interesting in the video is how the racket face is vertical when the ball comes into contact with the ball and how he is able to close it (de-loft it) and put top spin on the ball when it leaves the racket.

So the question would be is it possible to put a different spin on the ball by manipulating the club head with your hands after the golf ball comes into contact with the clubhead as Federer clearly does in this video with a tennis ball?

I realize if top spin were put on a golf ball like Federer's tennis ball the golf ball would not be in the air for very long. Still Federer is able to change the spin of the tennis ball while it's still in contact with the racket. I believe I've seen where it's said that once the golf ball is in contact with the clubface it's too late to alter spin / direction.

When RF's brain recieves the signal that his racquet hit the ball, where is the ball?

 

[Keefer]

He (Roger Federer) isn't delofting the racket, the ball hits the racket off-centre, the delofting happens because of that. Or do you think Federer deformed the racket on impact as well? Have a close look and you will see that the racket is deforming at impact. If the ball can deform the racket at impact, don't you think it can twist the racket as well?

I think the only person who could deform the racket at impact would be Uri Geller

Then I'd like to see a close up of him hitting a shot where he intentionally delofts the racket to hit a top spin shot and compare. I don't play tennis so not knowing all the different type shots is it possible that he intentionally hit's it off center to hit a different type shot? This shot clearly had top spin when it left his racket. Was it a good shot? Do we know?

 

[Keefer]

When RF's brain recieves the signal that his racquet hit the ball, where is the ball?

So what your saying is when a tennis player hits a shot with top spin, it's just dumb luck? Do we know what type shot he was trying to hit? Otherwise it's all speculation.

 

[mgranato]

And for the record...

This was not a Federer topspin forehand, this was him trying to get to a well placed ball with a stab stroke. Some are already saying this is the intended technique to hit a topspin forehand. An intentional mishit.

After college and before golf and my career as a amateur competitive eater, I played tennis at a pretty decent level (5.5). Got to train with some touring pros and college players. Not once did we work on the art of the mishit topspin winner.

They're nothing if not predicable.

Pay special attention to the last shot in this montage, a Federer topspin forehand. He's impacting high on the racquet (the opposite of Mike's clip), a mishit, but still hitting the same shot he setup and swung for. He's not changing anything "through impact" although impact is changing his racquet.

 

[mgranato]

So what your saying is when a tennis player hits a shot with top spin, it's just dumb luck? Do we know what type shot he was trying to hit? Otherwise it's all speculation.

Yes. He was stretching for a ball (I saw the match and have this slow motion shot on my DVR). A topspin shot is setup by face and path, not luck.

Care to answer the question? Where is the ball when he feels impact?

 

[hp12c]

Yes. He was stretching for a ball (I saw the match and have this slow motion shot on my DVR). A topspin shot is setup by face and path, not luck.

Care to answer the question? Where is the ball when he feels impact?

Granato I like that little gem! "shot is setup by face and path, not luck".

 

[birly-shirly]

Yes. He was stretching for a ball (I saw the match and have this slow motion shot on my DVR). A topspin shot is setup by face and path, not luck.

Care to answer the question? Where is the ball when he feels impact?

C'mon... 0:10s in that vid - you can't tell me that's not deliberate manipulation of the racquet.

 

[drewyallop]

Why wouldn't face and path determine direction and spin axis of a tennis ball (or for any ball for that matter)? I don't see any reason why the physics underlying the D-plane could not be generalized to any ball impact. Does anyone have another view?

It would be interesting to factor in the other parameters, AOA etc.

D-plane may play no part in tennis coaching today but neither was it used in golf teaching 5 years ago. I wouldn't be surprised if people like Tuxen are working now on expanding flight monitor technology to other sports (cue oliver and his mates for appropriate new cricket/Trackman terminology).

Drew

 

[mgranato]

Why wouldn't face and path determine direction and spin axis of a tennis ball (or for any ball for that matter)? I don't see any reason why the physics underlying the D-plane could not be generalized to any ball impact. Does anyone have another view?

It would be interesting to factor in the other parameters, AOA etc.

D-plane may play no part in tennis coaching today but neither was it used in golf teaching 5 years ago. I wouldn't be surprised if people like Tuxen are working now on expanding flight monitor technology to other sports (cue oliver and his mates for appropriate new cricket/Trackman terminology).

Drew

It's already been happening. Flightscope Tennis does all the radar tracking for Wimbledon and the WTA, and Flightscope Cricket does the ball tracking (Speedstick and Speedball) for that riveting sport. Only problem with the cricket radars is that a battery (or other power supply) does not exist that can last as long as a match.

That white structure in the background is the first cricket radar.

 

[Frans@France]

It's already been happening. Flightscope Tennis does all the radar tracking for Wimbledon and the WTA, and Flightscope Cricket does the ball tracking (Speedstick and Speedball) for that riveting sport.

... TrackMan is used in soccer and helped in designing soccer balls. Also there are some presentations of Trackman and basebal to be found.

 

[ParHunter]

So what your saying is when a tennis player hits a shot with top spin, it's just dumb luck? Do we know what type shot he was trying to hit? Otherwise it's all speculation.

Two things normally happen for a top spin shot.
The racket is going up and the racket is slightly tilted downward.

I reckon the path has more influence on the ball direction in tennis or table tennis then it would have in golf because otherwise these shots would end up in the nett. Or has this to do with dynamic loft?

 

[mgranato]

... TrackMan is used in soccer and helped in designing soccer balls. Also there are some presentations of Trackman and basebal to be found.

As I recall, that Adidas/TM soccer ball design didn't go over too well in the World Cup. Unless it was square, I have no idea what was complained about.

 

[birly-shirly]

Two things normally happen for a top spin shot.
The racket is going up and the racket is slightly tilted downward.

I reckon the path has more influence on the ball direction in tennis or table tennis then it would have in golf because otherwise these shots would end up in the nett. Or has this to do with dynamic loft?

Guessing here - but I think you're right, that path does have more influence on the ball's initial direction, and that it's because the impact interval is longer in tennis. Squashy ball, bouncy strings, lower speeds - all mean that there is a longer time frame in which to drag the ball in the direction of the racquet swing.

 

[Keefer]

Two things normally happen for a top spin shot.
The racket is going up and the racket is slightly tilted downward.

I reckon the path has more influence on the ball direction in tennis or table tennis then it would have in golf because otherwise these shots would end up in the nett. Or has this to do with dynamic loft?

The video looked to me like an intentional top spin shot (but I don't play tennis). Now people are saying no it was a mis-hit and because it was mis-hit on the bottom of the racket (in effect de-lofting the racket), that was the cause of the top spin. OK fine. Like I mentioned I have no idea what this rate of closure has to do with the price of fish anyway.

As far as intentionally hitting it off center for a deadened shot. I would think it would be similar to intentionally hitting a putt out on the toe to deaden the putt or trying to intentionally blade a wedge around the green, or chipping with the heel up and hitting it more on the toe etc., etc. for a specific shot.

As I said, I have no horse in this race. Just commented on what I saw (or thought I saw). I suppose to find out for sure you'd have to ask Federer what happened on that shot. Was it a mis-hit or was it an intended top spin shot.

 

[Brian Manzella]

Pure and Simple.

You CAN NOT make the face do ANYTHING during impact—even on purpose.

It is really a shame that folks waste time with this stuff.


Goofy.