Do You Hit Up On Your Serve

[larry10s]

i thought the pronation thread was getting off track and digressing imho. g did a fabulous job in that one (and the others)and at his summary probably new comments should have been started in a new thread imho. if the thread goes on forever it will be difficult when people serach to find what they are looking for. if you all agree you discuss whether topspin can be generated by hitting down, how well does your camera bend ,etc. here

[benne]

you're asking if you can hit a topspin serve without hitting up/brushing the ball up?

I personally can't...I don't think it's possible

[gzhpcu]

If you observe the tennis ball on the serve from the side, hitting down, causes the ball to rotate clockwise. Rotation clockwise, is backspin and causes the ball to "float". If you have an upward motion (hitting below the equator of the ball), then the ball rotates counterclockwise (am always talking about) causing topspin forcing the ball down.

Demonstrate this is not so, if you think otherwise.

[Rickson]

They claim everyone under 6'4 hits up on the serve. It's hard to imagine how Roddick serves so fast if he's hitting up on his serve.

[SystemicAnomaly]

Unfortunately, I am quite a bit shorter than 6' 10" (2.1 meters) and must hit up on the ball on the serve. I suppose that if I could could jump sufficiently high and into the court enough, I might be able to hit down if I was 6 and half feet tall. Otherwise, geometry dictates that I must hit up on the ball to get it into the box.

[SystemicAnomaly]

They claim everyone under 6'4 hits up on the serve. It's hard to imagine how Roddick serves so fast if he's hitting up on his serve.

The claim that I had heard was more like 6'7" tall. However, I don't believe that this takes into account jumping up & into the court. That figure might also not account for the downward curvature of the ball due to gravity. Nonetheless, must of us must hit up on the ball in order to get it over the net and into the box.

[Rickson]

How about a 6'4 guy with long arms? Perhaps an Alvin Robertson of Spurs fame if he played tennis.

[Jaewonnie]

flat serves, no (it sucks though)

kick serves, yes

[J011yroger]

How about a 6'4 guy with long arms? Perhaps an Alvin Robertson of Spurs fame if he played tennis.

That is a scary thought. . . I don't think I would want to play him in tennis, or bball for that matter.

J

[Ballinbob]

They claim everyone under 6'4 hits up on the serve. It's hard to imagine how Roddick serves so fast if he's hitting up on his serve.

2 more inches to go lol!

[J011yroger]

2 more inches to go lol!

Why do you tempt me to make comments that will get me in trouble with the mods?

J

[Ballinbob]

^^ Oh god hahahah are you thinking what I think you're thinking?! That wasn't my intention lol believe me:grin:

[stormholloway]

I think even if you were ten feet tall you would hit up on the serve. To my knowledge, your energy is always going up.

[SystemicAnomaly]

^ For the most part, this is absolutely true. The leg drive is upward and the racket head definitely moves upward from the racket drop toward the ball contact. I believe that the dispute by some is what happen during the ball contact (and the brief interval immediately prior to contact). Some claim that the racket (head) is driving the ball downward into the court. I believe that this claim is incorrect except for extremely tall people.

[stormholloway]

Actually, I'm inclined to agree that the racquet is driving the ball downward. Do some claim that gravity merely brings it down? A ball traveling as fast as some serves go isn't going to be swayed that much by gravity, at least not so much as to bring it downward into the court.

If you raise your racquet in the air and a bit in front of you, where'd you make contact, the face is pointing down several degrees. Therefore, in my 100% amateur/hacker opinion, the energy in the body goes up, while the racquet makes contact with the ball facing slightly down.

Only a patty cake serve would let gravity take the ball down into the court. If Roddick, for example, hit the ball 'up' the ball would go up.

[nousername]

to be honest, even for someone 9 ft tall, hitting up is still a fabulous idea.

the KEY to this discussion is understand the difference in attitude and velocity ... instead of writing it again, i point this out and describe it here (http://tt.tennis-warehouse.com/showpost.php?p=3237935&postcount=20)

hitting up simply put topspin on the ball, which creates better action and higher serve percentages ... no matter how tall! the closer to the net you can get the ball to land the more accentuated action you will get. thus irregardless of your height you want to hit UP with action.

it IS true that the taller you are the more the racket will and should face downward, but you will always want the brief upward velocity component during contact when serving.

[J011yroger]

I have attitude, and velocity.

Anyone on the boards who has attempted successfully or otherwise to return my serve can vouch for that :)

J

[gzhpcu]

you're asking if you can hit a topspin serve without hitting up/brushing the ball up?

I personally can't...I don't think it's possible
If the racket is not going up, even a little bit, it is impossible to impart topspin. Hitting down and getting topspin is nonsense.

[larry10s]

They claim everyone under 6'4 hits up on the serve. It's hard to imagine how Roddick serves so fast if he's hitting up on his serve.
dont understand your trying to connect pace with hitting up

[larry10s]

to be honest, even for someone 9 ft tall, hitting up is still a fabulous idea.

the KEY to this discussion is understand the difference in attitude and velocity ... instead of writing it again, i point this out and describe it here (http://tt.tennis-warehouse.com/showpost.php?p=3237935&postcount=20)

hitting up simply put topspin on the ball, which creates better action and higher serve percentages ... no matter how tall! the closer to the net you can get the ball to land the more accentuated action you will get. thus irregardless of your height you want to hit UP with action.

it IS true that the taller you are the more the racket will and should face downward, but you will always want the brief upward velocity component during contact when serving. i can visualize your statement that if you were tall enough you could be swinging up (and yandels work shows everyone swings up to impart spin) but the racquet face could be skewed slightly downward at contact. but im not sure you would be swinging down at that point. too bad we dont have a nice scientific study with video to show the answer.

[sureshs]

Actually, I'm inclined to agree that the racquet is driving the ball downward. Do some claim that gravity merely brings it down? A ball traveling as fast as some serves go isn't going to be swayed that much by gravity, at least not so much as to bring it downward into the court.

If you raise your racquet in the air and a bit in front of you, where'd you make contact, the face is pointing down several degrees. Therefore, in my 100% amateur/hacker opinion, the energy in the body goes up, while the racquet makes contact with the ball facing slightly down.

Only a patty cake serve would let gravity take the ball down into the court. If Roddick, for example, hit the ball 'up' the ball would go up.

I love you man

[sureshs]

I have attitude, and velocity.

Anyone on the boards who has attempted successfully or otherwise to return my serve can vouch for that :)

J

Did you mean altitude?

[Sublime]

herefore, in my 100% amateur/hacker opinion, the energy in the body goes up, while the racquet makes contact with the ball facing slightly down.

This is correct.

The balls trajectory is mostly defined by the angle of the racket face, not the direction of it's movement. Just like spin is mostly defined by the racket face movement and not the angle of the racket face.

[sureshs]

This is correct.

The balls trajectory is mostly defined by the angle of the racket face, not the direction of it's movement.

For flattish serves. For topspin serves, ball can be hit up but racquet face can be pointing down, but sideways to the ball. If the face points down straight in the direction the ball is gonna go, not sideways, it must be hitting down.

[gzhpcu]

For flattish serves. For topspin serves, ball can be hit up but racquet face can be pointing down, but sideways to the ball. If the face points down straight in the direction the ball is gonna go, not sideways, it must be hitting down.
You might have the racket angled slightly downward, but the racket must be moving up in respect to the ball, otherwise it is physically impossible to obtain topspin.

[sureshs]

No, you can hit down on the ball at points between 12 and 3 with a tangential motion and produce a component of topsin.

[gzhpcu]

No, you can hit down on the ball at points between 12 and 3 with a tangential motion and produce a component of topsin.

What you do not realize is that hitting down means brushing backwards.

[sureshs]

What you do not realize is that hitting down means brushing backwards.

Not when it is north of the equator

[stormholloway]

Depends on daylight savings time really.

[gzhpcu]

Not when it is north of the equator
If you hit down, you can only hit north of the equator. Try and visualize it. This is not about who is right, but what is right.

[sureshs]

“Looking at slow-motion video, you can see that the friction of the court grabs the bottom of the ball, while the top continues to rotate, adding more spin, and converting sidespin into almost pure topspin,” says videographer and tennis instructor John Yandell.

[sureshs]

If you hit down, you can only hit north of the equator. Try and visualize it. This is not about who is right, but what is right.

Both are right, depending on the ability, height, and circumstances.

[gzhpcu]

“Looking at slow-motion video, you can see that the friction of the court grabs the bottom of the ball, while the top continues to rotate, adding more spin, and converting sidespin into almost pure topspin,” says videographer and tennis instructor John Yandell.
Hey, this has no impact on the flight of the tennis ball through the air when serving prior to hitting the court! We are talking about imparting topspin at impact to force the ball downwards!

[W Cats]

dont understand your trying to connect pace with hitting up

I either read an article, post, or instructional vid once that did connect pace with hitting up on the ball. I believe the rationale went something like this - by hitting up on the ball peak racquet head speed was achieved closer to contact, whereas hitting down on the ball peak racquethead speed was reached after contact. It had something to do with the arc of the swing. Sorry I can't seem to recall the source. Anyone else run across this before?

[sureshs]

Hey, this has no impact on the flight of the tennis ball through the air when serving prior to hitting the court! We are talking about imparting topspin at impact to force the ball downwards!

But in one study I came across, the spin was measured after the bounce. In any case, what matters is what the opponent sees, which is after the bounce.

[gzhpcu]

But in one study I came across, the spin was measured after the bounce. In any case, what matters is what the opponent sees, which is after the bounce.
This is not what we were talking about. We were talking about imparting topspin at impact.

[sureshs]

This is not what we were talking about. We were talking about imparting topspin at impact.

But you were quoting rpm numbers. Now it turns out you can get numbers from other types of spin too, when they turn into topspin. So even sidespin imparted by a downward motion can become topspin.

And yes you can also impart topspin by hitting down at impact between 12 and 3.

[gzhpcu]

But you were quoting rpm numbers. Now it turns out you can get numbers from other types of spin too, when they turn into topspin. So even sidespin imparted by a downward motion can become topspin.

And yes you can also impart topspin by hitting down at impact between 12 and 3.
No, you can't. I suggest you study physics and mechanics. I had 4 years of it at university.

[gzhpcu]

But you know what? You can believe what you want. I am out of this discussion.

[nousername]

But you know what? You can believe what you want. I am out of this discussion.
good call ... the sad part is, as we know, this is a key concept in serve technique, and we want others to experience it too so they can reap the benefits... but then sureshs and co. come along at distract these discussions with meaningless pointless arguments ...

how in the world did sureshs start talking about the effect of the bounce on the serve??? ... nothing could have been further from the topic at hand.

anyway, i do i have one last idea: an animation. to show what "hitting up" is contrasted with sureshs's description of "hitting down". that will take time, but it may be worth it ... we'll see.

[drakulie]

I got some great photos and high speed video of over 20 pros this weekend while attending the Sony Ericsson Miami. Among them were: Isner (6'9"), and Mirnyi (6'5"), Tsonga (6'2"). I took the photos/videos directly from the side of the baseline where they were serving. Not one photo, or high speed video shows them hitting "down on the ball". Every photo captured where contact is being made>> the racquet face is perpendicular to the ground. More over the captured shots immediately before contact clearly shows the racquet traveling upwards, and immediately after shows the racquet traveling forward or up.

Will post some tonight when I get home.

[nousername]

I got some great photos and high speed video of over 20 pros this weekend while attending the Sony Ericsson Miami. Among them were: Isner (6'9"), and Mirnyi (6'5"), Tsonga (6'2"). I took the photos/videos directly from the side of the baseline where they were serving. Not one photo, or high speed video shows them hitting "down on the ball". Every photo captured where contact is being made>> the racquet face is perpendicular to the ground. More over the captured shots immediately before contact clearly shows the racquet traveling upwards, and immediately after shows the racquet traveling forward or up.

Will post some tonight when I get home.
cool. i look forward to seeing this stuff.

also, do you have pics, just as the ball is leaving the racket after serve contact? to be honest, the angle of the racket as the ball is leaving the stringbed is more important than at initial contact.

lastly (you know i'll ask sooner or later), please include the camera/video equipment used, and the FPS and the shutter speed. thanks.

[drakulie]

Isn't it obvious? It was for those who claimed that topspin can be produced by hitting up only. Even if that was true (and it is not), somebody could produce sidespin, which would become topspin after bounce. The topspin argument was being used backwards to refute the videos which shows pros hitting down on the ball some of the time.

suresh, you are obviously very passionate about your view. Is there any way you could video tape yourself hitting down on the ball between 12-3 (as you state), to see if the ball is rotating in any way upwards??

Hitting a forehand with a closed racquet face is one thing, because the racquet is still traveling up. However, hitting a serve with a closed racquet face, and swinging down is yet another.

[stormholloway]

How do we define "hitting down on the ball"?

[Puma]

I hate to bring this up. But, tennis instruction and research is years behind that of golf, and its a shame. This is why, in my opinion that Yandells work is so important. It is only with high speed camera that this question is going to be answered to any satisfactory degree. And possibly it already has, but you couldn't tell by this thread.

[Puma]

I would think that the rackets path in a serve swing resembles and upside down V. Half of the motion is going up and roughly have of it is going down. The small section in the middle is where the racket is changing directions. Exactly where the ball is struck in reference to this can only be answered with high speed cameras. Also racket face angle as well.

I would think that from player to player the exact impact point might change a little. This might be due to a players height, ball toss, type of serve and technique.

[stormholloway]

I got some great photos and high speed video of over 20 pros this weekend while attending the Sony Ericsson Miami. Among them were: Isner (6'9"), and Mirnyi (6'5"), Tsonga (6'2"). I took the photos/videos directly from the side of the baseline where they were serving. Not one photo, or high speed video shows them hitting "down on the ball". Every photo captured where contact is being made>> the racquet face is perpendicular to the ground. More over the captured shots immediately before contact clearly shows the racquet traveling upwards, and immediately after shows the racquet traveling forward or up.

Will post some tonight when I get home.

So are you claiming that spin and/or gravity brings the ball down into the service box? And how can you really say with certainty that the racquet is perpendicular to the ground? That would take some fairly precise instrumentation.

[Nellie]

Let's do a little math -

Assume, for ease, that the serve is travelling 100MPH constantly (not unreasonable since it starts faster and slows down and likely equivalent to a 120mph serve)

This works out to about 146.7 feet per second (100MPH*5280ft /60 sec/ 60min.) The distance from the center of the baseline to the tee is 60 feet (21 feet from service line to net + 39 feet from net to baseline), so this time of travel is about .41 seconds.

Falling distance = half (Gravity constant *time squared), where the gravity constant is 9.8 m/sec^2.

Distance falling for .41 seconds is about 1.65 m, or about 5.4 feet.

The height of contact for a serve is definitely higher than this, so you have to hit slightly down or the ball will go long (assuming no spin!)

Lets say your contact is about 9 feet, I would not think that you would need much to bring the ball down the extra 3.5 feet (such as contact at 2.9 o'clock) or some spin on the ball

(Compare with an 80 mph constant serve (about 100MPH initial serve) that falls about 8.3 feet from gravity, so then you would not need much additional downward force at all.)

[sureshs]

^^^^ air drag not accounted for

[stormholloway]

I don't understand how you can use that falling distance for a serve. The ball isn't being dropped for .41 seconds.

[sureshs]

I don't understand how you can use that falling distance for a serve. The ball isn't being dropped for .41 seconds.


2 dimensional projectile motion decomposed into horizontal and vertical components

[Nellie]

^^^^ air drag not accounted for

thus, the assumption of a lower constant speed, and this was not meant be super precise (e.g., no evaluation of spin)

[Nellie]

I don't understand how you can use that falling distance for a serve. The ball isn't being dropped for .41 seconds.

yeah - if you throw a ball horizontally (no up force) or drop it, it will hit the ground at the same time.

[stormholloway]

yeah - if you throw a ball horizontally (no up force) or drop it, it will hit the ground at the same time.

I hope you're joking.

[sureshs]

I hope you're joking.

No, gravity does not have horizontal component. That is why you can decompose it into two independent motions.

[Puma]

Let's do a little math -

Assume, for ease, that the serve is travelling 100MPH constantly (not unreasonable since it starts faster and slows down and likely equivalent to a 120mph serve)

This works out to about 146.7 feet per second (100MPH*5280ft /60 sec/ 60min.) The distance from the center of the baseline to the tee is 60 feet (21 feet from service line to net + 39 feet from net to baseline), so this time of travel is about .41 seconds.

Falling distance = half (Gravity constant *time squared), where the gravity constant is 9.8 m/sec^2.

Distance falling for .41 seconds is about 1.65 m, or about 5.4 feet.

The height of contact for a serve is definitely higher than this, so you have to hit slightly down or the ball will go long (assuming no spin!)

Lets say your contact is about 9 feet, I would not think that you would need much to bring the ball down the extra 3.5 feet (such as contact at 2.9 o'clock) or some spin on the ball

(Compare with an 80 mph constant serve (about 100MPH initial serve) that falls about 8.3 feet from gravity, so then you would not need much additional downward force at all.)


While I claim no working knowledge of physics I have to question your claim that a ball projected horizontal at 100 mph will fall 8.3 feet in 60 feet traveled. Please explain, or am I reading this wrong?

[stormholloway]

So if I take a loaded gun in one hand and a bullet in the other, then fire the gun horizontally and drop the bullet at the same time, the bullets will hit the ground simultaneously?

[bhupaes]

So if I take a loaded gun in one hand and a bullet in the other, then fire the gun horizontally and drop the bullet at the same time, the bullets will hit the ground simultaneously?

Yes... as counter-intuitive as it seems.

[sureshs]

So if I take a loaded gun in one hand and a bullet in the other, then fire the gun horizontally and drop the bullet at the same time, the bullets will hit the ground simultaneously?

Yes, not taking air resistance into effect.

[stormholloway]

That concept is beyond me. I'm going to forget I ever thought of it altogether.

[J011yroger]

Sureshs, can you put up a video of you serving?

J

[drakulie]

Let's do a little math -

Assume, for ease, that the serve is travelling 100MPH constantly (not unreasonable since it starts faster and slows down and likely equivalent to a 120mph serve)

This works out to about 146.7 feet per second (100MPH*5280ft /60 sec/ 60min.) The distance from the center of the baseline to the tee is 60 feet (21 feet from service line to net + 39 feet from net to baseline), so this time of travel is about .41 seconds.

Falling distance = half (Gravity constant *time squared), where the gravity constant is 9.8 m/sec^2.

Distance falling for .41 seconds is about 1.65 m, or about 5.4 feet.

The height of contact for a serve is definitely higher than this, so you have to hit slightly down or the ball will go long (assuming no spin!)

Lets say your contact is about 9 feet, I would not think that you would need much to bring the ball down the extra 3.5 feet (such as contact at 2.9 o'clock) or some spin on the ball

(Compare with an 80 mph constant serve (about 100MPH initial serve) that falls about 8.3 feet from gravity, so then you would not need much additional downward force at all.)


9 Feet Tall For A No Spin Serve?

http://www.tennisserver.com/set/images/jani.jpg
Jani Macari Pallis, Ph.D.
Years ago there was a misconception, perhaps more appropriately termed "tennis lore," that you had to be 9 feet tall to get a flat (no spin) serve in. With 6 ft. 10in. Croatian, Ivo Karlovic knocking out No. 1 seed Lleyton Hewitt at Wimbledon after the first round, I thought we would demonstrate the mathematics of this particular trajectory scenario.
First of all this isn't true. You don't have to be 9 feet tall nor does your combined height including your extended arm, racquet, and jump height need to be 9 feet or more. This is because both gravity and aerodynamic drag act on the ball during its flight. Gravity accelerates the ball downwards while drag (air resistance) creates a retarding force slowing the ball's forward motion. This causes a curved trajectory.
Where did the "9 feet" come from? If you look strictly at the geometry of a tennis court and the minimum angle it would take to hit the ball from the baseline, clear the net and land in the service court, you find that the ball needs to be hit from a height of about 9 feet.
Here's how this works. Here is a diagram of a tennis court and its dimensions including the net. The scenario: you serve just outside the baseline; the ball just clears the net down the middle and lands just inside the service court.
Draw a straight line from the court impact point, over the net and extend that straight line to the baseline. Now we'll use a little trigonometry to determine the height the ball was struck at to achieve this. There are several ways to do this. Perhaps the easiest is to just draw your diagram to scale. The distance from the baseline to the opposing service line is 60 feet. At the center, the net is 3 feet. The diameter of the ball is about 2.6 inches in diameter so we need at add at least an inch or two from the middle of the ball to make sure it clears the net. If you scale this correctly and then measure the height from the ground at the baseline to the point the straight line " trajectory" crosses the baseline, you get just about 9 feet.
http://www.tennisserver.com/set/images/set_03_07/ninefeet.jpg



However as you can see, this scenario does not take into consideration gravity, aerodynamic drag or even the velocity of the ball or the angle it is hit. A while back we had two articles regarding tennis ball trajectories called Trajectories 101A (http://www.tennisserver.com/set/set_02_01.html) and Trajectories 101B (http://www.tennisserver.com/set/set_02_02.html). In particular, Trajectories 101B (http://www.tennisserver.com/set/set_02_02.html) presented equations of motion which account for gravity and aerodynamic drag. The column mentioned a web-based interactive program which uses those equations that you can have some fun with, called SportSim (http://cislunar.com/SEE/traj_04.html). (It takes about 30 seconds for the page to load.) You can play with the values of speed and height and determine that you do not have to be 9 feet tall (108 inches) to get a no spin serve in. Here's an example of the ball struck at about 85 miles per hour and 92 inches high.


http://www.tennisserver.com/set/set_03_07.html

[bhupaes]

Good thread, in spite of the heat this topic has generated...

I went back and looked at a number of slow motion serve videos, and it was pretty illuminating. From the side, it does look like no one is hitting up, but no one is really hitting down either - the racquet face is pretty close to perpendicular, and even second serves look flat. But the view from front or behind tells a different story - there is a massive sideswiping action (result of pronation) that would seem to impart much more sidespin than topspin. The actual contact point is never in front of the ball, of course - so I have to disagree with Suresh on the 2-to-8 swipe in front of the ball. Depending on the serve/server, the contact point seems to vary from slightly to the left of center (the inside) to slightly to right of center (outside) for righties. More servers seem to prefer the ouside contact point than the inside. It is possible that while the racquet head itself seems to be moving downwards as a whole, the strings are actually moving up as a result of the sideswiping action. Hard to tell, but that is the only way topspin could be imparted, IMO.

I couldn't get anything more from the videos.

[gzhpcu]

Right. What is also being neglected is that we are not talking about hard billard balls here, but relatively soft tennis balls. Have you ever seen the extreme distortion and squashing of the ball at impact, as well as the trampoline effect of the rackets strings? The contact point is huge.

[drakulie]

Biomechanics In Tennis - Part 3

http://www.tennisserver.com/set/images/jani.jpg
Jani Macari Pallis, Ph.D.
In the previous column (http://www.tennisserver.com/set/set_03_09.html) we began a discussion of serve biomechanics (with thanks to Pete Sampras). Several graphics of racquet head patterns were included within the article and I asked if you could determine which patterns were flat, kick or slice serves. I also noted that we'd include the velocity of the tip of the racquet head in this month's column.
Again my fellow Tennis Server writer, Ron Waite, has two great articles on the first (http://www.tennisserver.com/turbo/turbo_01_07.html) and second serve (http://www.tennisserver.com/turbo/turbo_01_08.html) which review the flat, slice and kick serves from grip to finish. (Ron includes some nice photos of professionals performing these strokes as well.)
There are a couple of things that we'd like to point out about the diagrams.
The footage was taken from the sideline at the baseline.
The ball is in yellow. You can see the ball falling from the toss and its path once it has been hit.
The racquet head pattern is in blue and is composed of about 200 points.
When the points are close together that means the velocity is low. When the points are farther apart, the velocity is higher. Speed is calculated by dividing the distance between two points by the time.
You may note that most of the diagrams have two "empty spots" which correspond to the pre-toss. Those points are where Sampras' legs were. The racquet head tip was out sight when it passed in front of his legs.
http://www.tennisserver.com/set/images/set_03_09/Sampras-Serve-otln-sm.gif (http://www.tennisserver.com/set/images/set_03_09/Sampras-Serve-otln-lg.gif)
Serves Were Captured From The Sideline Near The Baseline Facing Sampras From The Left Side Of His Body



Could you pick out the patterns? Take your racquet; go through the motions and visualize the pattern of the racquet tip. You or a friend can also perform the stroke in front of a wall where you can make a shadow. Watch the shadow of the racquet head tip and see which graphic pattern it matches as you go through the motion of a flat, slice or kick serve. If that is still too difficult to see you can tape a ping-pong or little Styrofoam ball to the racquet tip which makes it easier to pick the racquet head tip out.
http://www.tennisserver.com/set/images/set_03_09/Set_1335.jpg (http://www.tennisserver.com/set/images/set_03_09/Set_1360.jpg)
Sampras Flat Serve http://www.tennisserver.com/set/images/set_03_09/Set_1735.jpg (http://www.tennisserver.com/set/images/set_03_09/Set_1760.jpg)
Sampras Flat Serve

[drakulie]

continued:



http://www.tennisserver.com/set/images/set_03_09/Set_1235.jpg (http://www.tennisserver.com/set/images/set_03_09/Set_1260.jpg)
Sampras Slice Serve
http://www.tennisserver.com/set/images/set_03_09/Set_1435.jpg (http://www.tennisserver.com/set/images/set_03_09/Set_1460.jpg)
Sampras Slice Serve
http://www.tennisserver.com/set/images/set_03_09/Set_2035.jpg (http://www.tennisserver.com/set/images/set_03_09/Set_2060.jpg)
Sampras Kick Serve
http://www.tennisserver.com/set/images/set_03_09/Set_1835.jpg (http://www.tennisserver.com/set/images/set_03_09/Set_1860.jpg)
Sampras Kick Serve


Now we've labeled the serves. Intuitively this makes sense. The flat serve has little spin. As contact with the ball is made, the racquet head moves forward. If you are right-handed, the racquet crosses the body and finishes on your left side.
In the slice, the finish is similar in that again the racquet finishes on the opposite side of your body. In the kick serve the racquet has brushed the ball moving from lower left to upper right and the racquet finishes on the dominant hand side of your body (right-handers finish on the right, left-handers finish on the left).
Sampras was the first player on which this analysis had been conducted. After seeing this beautiful fluid circular motion I assumed every pro player must have a similar motion flow. WRONG! Here's the pattern of a first and second serve of a young Venus Williams at her first US Open in 1997. Aside from a very different serve pattern, look at the first and second serves. The patterns are quite similar. Instead of the distinct serves Sampras used, Williams basically used the same serve every time. (This wasn't an isolated case -- comparing a series of William's serves produced the same results.)

[drakulie]

BTW, guys.... sorry I wasn't able to upload the photos from the sony. Didn't have time last night to sort all the photos out.

[Nellie]

Drak.

Could point! I was assuming that the path was pretty straight which is obviously wrong.

[drakulie]

^^Yup, you could clearly see the racquet face is traveling **UP*. Additionally, this is even more evident on spin serves, where the racquet continues to travel **UP*, even after contact.

[bhupaes]

Right. What is also being neglected is that we are not talking about hard billard balls here, but relatively soft tennis balls. Have you ever seen the extreme distortion and squashing of the ball at impact, as well as the trampoline effect of the rackets strings? The contact point is huge.

Agreed. The exact analysis would become quite complex, I think, as a result.

And thanks, Drakulie, for posting these articles - they are very interesting.

[sureshs]

Good thread, in spite of the heat this topic has generated...

I went back and looked at a number of slow motion serve videos, and it was pretty illuminating. From the side, it does look like no one is hitting up, but no one is really hitting down either - the racquet face is pretty close to perpendicular, and even second serves look flat. But the view from front or behind tells a different story - there is a massive sideswiping action (result of pronation) that would seem to impart much more sidespin than topspin. The actual contact point is never in front of the ball, of course - so I have to disagree with Suresh on the 2-to-8 swipe in front of the ball. Depending on the serve/server, the contact point seems to vary from slightly to the left of center (the inside) to slightly to right of center (outside) for righties. More servers seem to prefer the ouside contact point than the inside. It is possible that while the racquet head itself seems to be moving downwards as a whole, the strings are actually moving up as a result of the sideswiping action. Hard to tell, but that is the only way topspin could be imparted, IMO.

I couldn't get anything more from the videos.

If the racquet head is moving down, the strings can move down and sideways only, not up. They are constrained by the boundaries of the frame.

And the sidespin produced by the sideswipe can become topspin after contact with the ground, when the axis changes.

And I am perfectly willing to believe that Sampras hits up on the ball, so let me be clear on that.

I was watching Serena vs Jie Zheng, and Serena hit those hard flat out-wide serves which seem to clear the net by inches. Just a hard downward whack on the ball, no topspin.

[stormholloway]

So if the energy transferred from the strings to the ball is directed upward, what is bringing the ball down?

[sureshs]

Drakulie carefully omitted the Venus serve hitting down:

http://www.tennisserver.com/set/images/set_03_11/VW1st-No_Vel.jpg

[JediMindTrick]

So if the energy transferred from the strings to the ball is directed upward, what is bringing the ball down?

The topspin for sure.

[drakulie]

^^Spin. When the strings brush up on the ball, it imparts spin.

Same thing as when you hit a FH. You brush up on the ball, thus creating the spin needed to bring the ball back down into the court.

[drakulie]

Drakulie carefully omitted the Venus serve hitting down:

http://www.tennisserver.com/set/images/set_03_11/VW1st-No_Vel.jpg

the racquet is still going up even after contact.

[drakulie]

Here is the venus williams. Clearly hitting **UP**


WRONG! Here's the pattern of a first and second serve of a young Venus Williams at her first US Open in 1997. Aside from a very different serve pattern, look at the first and second serves. The patterns are quite similar. Instead of the distinct serves Sampras used, Williams basically used the same serve every time. (This wasn't an isolated case -- comparing a series of William's serves produced the same results.)

http://www.tennisserver.com/set/images/set_03_11/VW1st-No_Vel-sm.jpg (http://www.tennisserver.com/set/images/set_03_11/VW1st-No_Vel.jpg)
Venus Williams First Serve http://www.tennisserver.com/set/images/set_03_11/VW2nd-No_Vel-sm.jpg (http://www.tennisserver.com/set/images/set_03_11/VW2nd-No_Vel.jpg)
Venus Williams Second Serve

[stormholloway]

The topspin for sure.

^^Spin. When the strings brush up on the ball, it imparts spin.

Same thing as when you hit a FH. You brush up on the ball, thus creating the spin needed to bring the ball back down into the court.

Completely disagree. A flat serve doesn't have the kind of flight path a topspin forehand or a kick serve have by any stretch. Spin alone could not be enough to bring the flattest serves down as they do.

The ball is moving downward immediately as it's hit. You're telling me spin acts on it that quickly? On a topspin forehand the ball beings by moving upward then spin and gravity act on it. On a flat serve the ball immediately moves downward and with a relatively straight flight path.

[drakulie]

Completely disagree. A flat serve doesn't have the kind of flight path a topspin forehand or a kick serve have by any stretch. Spin alone could not be enough to bring the flattest serves down as they do.

The ball is moving downward immediately as it's hit. You're telling me spin acts on it that quickly? On a topspin forehand the ball beings by moving upward then spin and gravity act on it. On a flat serve the ball immediately moves downward and with a relatively straight flight path.

9 Feet Tall For A No Spin Serve?

http://www.tennisserver.com/set/images/jani.jpg
Jani Macari Pallis, Ph.D.
Years ago there was a misconception, perhaps more appropriately termed "tennis lore," that you had to be 9 feet tall to get a flat (no spin) serve in. With 6 ft. 10in. Croatian, Ivo Karlovic knocking out No. 1 seed Lleyton Hewitt at Wimbledon after the first round, I thought we would demonstrate the mathematics of this particular trajectory scenario.
First of all this isn't true. You don't have to be 9 feet tall nor does your combined height including your extended arm, racquet, and jump height need to be 9 feet or more. This is because both gravity and aerodynamic drag act on the ball during its flight. Gravity accelerates the ball downwards while drag (air resistance) creates a retarding force slowing the ball's forward motion. This causes a curved trajectory.
Where did the "9 feet" come from? If you look strictly at the geometry of a tennis court and the minimum angle it would take to hit the ball from the baseline, clear the net and land in the service court, you find that the ball needs to be hit from a height of about 9 feet.
Here's how this works. Here is a diagram of a tennis court and its dimensions including the net. The scenario: you serve just outside the baseline; the ball just clears the net down the middle and lands just inside the service court.
Draw a straight line from the court impact point, over the net and extend that straight line to the baseline. Now we'll use a little trigonometry to determine the height the ball was struck at to achieve this. There are several ways to do this. Perhaps the easiest is to just draw your diagram to scale. The distance from the baseline to the opposing service line is 60 feet. At the center, the net is 3 feet. The diameter of the ball is about 2.6 inches in diameter so we need at add at least an inch or two from the middle of the ball to make sure it clears the net. If you scale this correctly and then measure the height from the ground at the baseline to the point the straight line " trajectory" crosses the baseline, you get just about 9 feet.

http://www.tennisserver.com/set/images/set_03_07/ninefeet.jpg



However as you can see, this scenario does not take into consideration gravity, aerodynamic drag or even the velocity of the ball or the angle it is hit. A while back we had two articles regarding tennis ball trajectories called Trajectories 101A (http://www.tennisserver.com/set/set_02_01.html) and Trajectories 101B (http://www.tennisserver.com/set/set_02_02.html). In particular, Trajectories 101B (http://www.tennisserver.com/set/set_02_02.html) presented equations of motion which account for gravity and aerodynamic drag. The column mentioned a web-based interactive program which uses those equations that you can have some fun with, called SportSim (http://cislunar.com/SEE/traj_04.html). (It takes about 30 seconds for the page to load.) You can play with the values of speed and height and determine that you do not have to be 9 feet tall (108 inches) to get a no spin serve in. Here's an example of the ball struck at about 85 miles per hour and 92 inches high.


http://www.tennisserver.com/set/set_03_07.html

[drakulie]

Storm, also, you could clearly see in **ALL** all these serves the flight path has a "downward" trajectory. "FLAT, SLICE, TOPSPIN".

To add, in actuality, the Topspin serve has a more maginfied downward trajectory, than the slice or flat.


http://www.tennisserver.com/set/images/set_03_09/Set_1235.jpg (http://www.tennisserver.com/set/images/set_03_09/Set_1260.jpg)
Sampras Slice Serve
http://www.tennisserver.com/set/images/set_03_09/Set_1435.jpg (http://www.tennisserver.com/set/images/set_03_09/Set_1460.jpg)
Sampras Slice Serve
http://www.tennisserver.com/set/images/set_03_09/Set_2035.jpg (http://www.tennisserver.com/set/images/set_03_09/Set_2060.jpg)
Sampras Kick Serve
http://www.tennisserver.com/set/images/set_03_09/Set_1835.jpg (http://www.tennisserver.com/set/images/set_03_09/Set_1860.jpg)
Sampras Kick Serve

[sureshs]

Here is the venus williams. Clearly hitting **UP**


WRONG! Here's the pattern of a first and second serve of a young Venus Williams at her first US Open in 1997. Aside from a very different serve pattern, look at the first and second serves. The patterns are quite similar. Instead of the distinct serves Sampras used, Williams basically used the same serve every time. (This wasn't an isolated case -- comparing a series of William's serves produced the same results.)

http://www.tennisserver.com/set/images/set_03_11/VW1st-No_Vel-sm.jpg (http://www.tennisserver.com/set/images/set_03_11/VW1st-No_Vel.jpg)
Venus Williams First Serve http://www.tennisserver.com/set/images/set_03_11/VW2nd-No_Vel-sm.jpg (http://www.tennisserver.com/set/images/set_03_11/VW2nd-No_Vel.jpg)
Venus Williams Second Serve



In the first serve, the racquet is past its highest point which was to the right of the ball between the blue points.

[sureshs]

So if the energy transferred from the strings to the ball is directed upward, what is bringing the ball down?

Gravity and air drag (which is also responsible for spin)

[stormholloway]

Drakulie: you just pasted stuff you had already posted. It didn't really answer the question.

Gravity and air drag (which is also responsible for spin)

Gravity and air drag don't immediately send a ball downward. If I throw a tennis ball even slightly upward, it goes up first. Why would a MUCH faster serve be different?

[sureshs]

Drakulie: you just pasted stuff you had already posted. It didn't really answer the question.



Gravity and air drag don't immediately send a ball downward. If I throw a tennis ball even slightly upward, it goes up first. Why would a MUCH faster serve be different?

Gravity and air drag act all the time. All that is needed is for the ball height to fall so that it lands within the service box.

Air drag acts in two ways - it slows the ball down, thus reducing the distance it can cover in a certain time. It also acts differently on the top and bottom portions of a spinning ball, dragging along with the ball or opposite to it. This causes a topspin ball to experience a downward force, and an underspin ball to experience an upward force (like the lift of a plane). Gravity of course is there.

When you say these things don't immediately send a ball downward, you need to keep in mind that they are acting all the time, right from the moment the ball leaves the strings. They don't need a "time to act."

[Kaptain Karl]

sureshs, you are not visualizing where the server's feet are, IMO. If you think about the line from the tip of the racquet to the tip of the toes, it "leans" into the court. Therefore, in relation to the line of the body, Venus is still hitting UP on the ball.

No, you can hit down on the ball at points between 12 and 3 with a tangential motion and produce a component of topsin.Not if you want the serve to go IN.

I remember an article in (World Tennis? Tennis?) many years ago, where they showed 7'2" Wilt Chamberlin (sp?) at the Baseline with racquet extended and a straight line drawn on the photo to the other side. The ball would still have gone OUT. (Of course, the article didn't account for gravity, drag and spin.)

If you want your "Flat" serve to go IN, you must hit UP on the ball.

- KK

[JediMindTrick]

Completely disagree. A flat serve doesn't have the kind of flight path a topspin forehand or a kick serve have by any stretch. Spin alone could not be enough to bring the flattest serves down as they do.

The ball is moving downward immediately as it's hit. You're telling me spin acts on it that quickly? On a topspin forehand the ball beings by moving upward then spin and gravity act on it. On a flat serve the ball immediately moves downward and with a relatively straight flight path.

That's a good point actually, but I'm not going to answer it.

I think there is a confusion here because some people think that this debate is about if you can hit down on the ball and get the serve in. The answer is obviously yes, that how most club players hit the flat serve. The problem is not that you cannot do it, but you cannot do it consistently because if you hit down, the ball will have underspin and your margin of error is very small. That's why most club players have a low percentage flat serve, but they think the pros have better percentage because they practice more. So the club players keep practicing the same technically incorrect serve for years and still can't improve the percentage. So the debate is not if you can hit down on the ball, but if you should hit down on the ball.

[sureshs]

sureshs, you are not visualizing where the server's feet are, IMO. If you think about the line from the tip of the racquet to the tip of the toes, it "leans" into the court. Therefore, in relation to the line of the body, Venus is still hitting UP on the ball.

Not if you want the serve to go IN.

I remember an article in (World Tennis? Tennis?) many years ago, where they showed 7'2" Wilt Chamberlin (sp?) at the Baseline with racquet extended and a straight line drawn on the photo to the other side. The ball would still have gone OUT. (Of course, the article didn't account for gravity, drag and spin.)

If you want your "Flat" serve to go IN, you must hit UP on the ball.

- KK

Hitting down won't make a ball go in but hitting up will? If anything, hitting down would make it go into the net too quickly.

And the article should account for gravity, drag and spin. Actually, without those, a serve which is hit up will be on its way to some galaxy far far away.

[sureshs]

http://video.aol.com/video-detail/rafael-nadal-serve-in-slow-motion/2375537516/?icid=VIDURVSPR02

Go to 0:18 and click frame by frame. Please notice that the Drakulie effect (to be taken in a good sense - like Newton's laws) distorts the image - the racquet appears pointing up and bent. Take that into account by mentally extending the shaft and ignoring the bent head. You will eventually see that the highest point has just been crossed when the ball is hit and it is launched just a wee bit south of horizon - the almost horizontal path can be seen till 0:19 till it clears the second light post.

[sureshs]

That's a good point actually, but I'm not going to answer it.

I think there is a confusion here because some people think that this debate is about if you can hit down on the ball and get the serve in. The answer is obviously yes, that how most club players hit the flat serve. The problem is not that you cannot do it, but you cannot do it consistently because if you hit down, the ball will have underspin and your margin of error is very small. That's why most club players have a low percentage flat serve, but they think the pros have better percentage because they practice more. So the club players keep practicing the same technically incorrect serve for years and still can't improve the percentage. So the debate is not if you can hit down on the ball, but if you should hit down on the ball.

In fact, the very first time I posted about this a long time ago, I said that every other club player hits down on the ball, sometimes with atrocious Eastern grips and achieves flat serves. This is what I observed in real life and that is why I posted it - and it contradicted the claim someone was making that geometry prevents the serves from happening (you need to take into account the total height and the distance moved into the court). In fact, the oldies I played with yesterday (Mario and Dana - real names) hit this all the time except Mario is a short guy and so cannot do it as consistently as Dana. Dana knows how to angle the ball sideways effectively giving him a longer distance in which to get the ball in.

Then someone changed the discussion to focus it in pro serves. I pointed out that an oldie who has a consistent flat serve hitting down is much better than someone who hits up like Sampras but with a millionth of his topspin and sails the ball long 99% of the time - who will you pick as a doubles partner?

[stormholloway]

Gravity and air drag act all the time. All that is needed is for the ball height to fall so that it lands within the service box.

Air drag acts in two ways - it slows the ball down, thus reducing the distance it can cover in a certain time. It also acts differently on the top and bottom portions of a spinning ball, dragging along with the ball or opposite to it. This causes a topspin ball to experience a downward force, and an underspin ball to experience an upward force (like the lift of a plane). Gravity of course is there.

When you say these things don't immediately send a ball downward, you need to keep in mind that they are acting all the time, right from the moment the ball leaves the strings. They don't need a "time to act."

But where's the evidence that these things are working in such a way as to produce this result?

If the racquet face were pointing upward to any degree when the ball leaves the strings then the ball would go up. The racquet face, however, is pointing slightly down while the strings are moving up the back of the ball. In other words, a flat serve is a very very flat kick serve. The difference in a kick serve is that there is not enough direct impact of the strings to bring it into the box without spin.

[sureshs]

There is something very important in Jedi's post: the reference to underspin.

It maybe difficult to understand the first time. Hitting down for a flat serve and underspin? How come? Isn't underspin only with slice?

For those who have played with TT balls, it will be much clearer. A ball hit down at an angle does not really shoot down like a bullet - the dragging action during the dwell time of the ball creates a slight underspin - causing the ball trajectory to become more horizontal with time (even appearing to float).

This is one of the reasons why the geometry analysis is wrong (other reasons are not taking into account total height and the distance into the court that it is hit). A ball hit down is slightly floated up and can clear the net due to the above reason. Just like topspin brings a ball down, underspin brings it up, even if it is ever so little.

[sureshs]

But where's the evidence that these things are working in such a way as to produce this result?

If the racquet face were pointing upward to any degree when the ball leaves the strings then the ball would go up. The racquet face, however, is pointing slightly down while the strings are moving up the back of the ball. In other words, a flat serve is a very very flat kick serve. The difference in a kick serve is that there is not enough direct impact of the strings to bring it into the box without spin.

You put me in an awkward situation because what you say supports my point but yet I have to disagree with you. If the strings are moving up, the ball is being hit up, even if the face is pointing down (it will be pointing sideways too).

[stormholloway]

Define "hitting up".

If the ball is compressed against the strings and the racquet face is facing down, is that hitting up? The strings are a trampoline. What you're admitting is that in every serve the strings are indeed facing down when the ball leaves the racquet. If that's "hitting up" then this is only an issue of semantics, but I cannot imagine how spin is what brings the ball down in a flat serve.

Ultimately, you're not hitting up or down. The racquet is being swung in an elliptical path and the ball leaves that ellipsis tangentially.

[Djokovicfan4life]

Talk about much ado about nothing.

All I know is, when I hit up my serve goes in with better power and margin for error, so I'm gonna go with that.

[stormholloway]

At this point it's just a debate for entertainment. I will say this: in this picture the ball is hit after it reaches its highest point, which means the racquet face must be facing down.

http://www.tennisserver.com/set/images/set_03_11/VW1st-No_Vel.jpg

Nobody needs to think about these things. The serve just happens (unless you're me).

[bad_call]

Talk about much ado about nothing.

All I know is, when I hit up my serve goes in with better power and margin for error, so I'm gonna go with that.

u forgot to mention your height...5' 1". :)

[sureshs]

Ultimately, you're not hitting up or down. The racquet is being swung in an elliptical path and the ball leaves that ellipsis tangentially.


True. Question is at what height of the elliptical trajectory is the ball being struck.

A very interesting fact pointed out by someone here is the dwell time of the ball. As the racquet is moving, the ball is being compressed against the strings for a small but significant amount of time. This adds a further twist because now we are talking about an interval of time, rather than a moment.

[Djokovicfan4life]

u forgot to mention your height...5' 1". :)

Um, last I measured was years ago, at 6'0. I'm 19 now, so I'd say I was probably 15-16 at the time. That said, it wouldn't surprise me if I was 6'2-6'3 now. Also, people tell me that my arms are unusually long, so I've got that going for me as well.

Bearing in mind that my serve isn't perfect, I still say, HIT UP!

P.S. Maybe the avatar threw you off a tad?

[bad_call]

Um, last I measured was years ago, at 6'0. I'm 19 now, so I'd say I was probably 15-16 at the time. That said, it wouldn't surprise me if I was 6'2-6'3 now.

wow then u shouldn't need to hit up. i'm 5' 10" and don't hit up. btw - kidding about the height thing. :)

[drakulie]

At this point it's just a debate for entertainment. I will say this: in this picture the ball is hit after it reaches its highest point, which means the racquet face must be facing down.

http://www.tennisserver.com/set/images/set_03_11/VW1st-No_Vel.jpg

Nobody needs to think about these things. The serve just happens (unless you're me).


Storm, keep in mind in these images that the yellow balls you see (on one top of the other) are from the toss. The ball is coming down from the toss, and then it is hit, and as a result you see the ball now moving forward.

One other thing that you are confusing. Even though the racquet is traveling upwards, this does not mean the strings are hitting the bottom of the ball. The racquet face travels upwards, however before impact the racquet has reached perpendicular and hits the **back** of the ball, not the bottom. This is why the ball moves forward and down, and not "up". Of course, as the article points out, there is gravity, drag, etc that also come into play.

[Djokovicfan4life]

wow then u shouldn't need to hit up. i'm 5' 10" and don't hit up. btw - kidding about the height thing. :)

I know, the smiley tipped me off.

I just hate these stereotypes about serving and height limitations. My little brother clocked his first 100 MPH serve the other day. He's 14, about 5'7, if I had to guess.

Just saying.

[sureshs]

At this point it's just a debate for entertainment. I will say this: in this picture the ball is hit after it reaches its highest point, which means the racquet face must be facing down.

http://www.tennisserver.com/set/images/set_03_11/VW1st-No_Vel.jpg

Nobody needs to think about these things. The serve just happens (unless you're me).


Not only that, the racquet has reached its heighest point between the two blue dots and is starting down as it hits the ball.

[drakulie]

Sureshs, can you put up a video of you serving?

J


I would also like to see what he is talking about when he says one can hit the ball down between 12-3 and impart topspin.

[stormholloway]

True. Question is at what height of the elliptical trajectory is the ball being struck.

A very interesting fact pointed out by someone here is the dwell time of the ball. As the racquet is moving, the ball is being compressed against the strings for a small but significant amount of time. This adds a further twist because now we are talking about an interval of time, rather than a moment.

I thought about mentioning the dwell time earlier but thought it would just complicate things. For all we know, the ball hits the strings with the racquet facing upward and leaves with the racquet facing slightly downward.

Sad thing is, none of this is going to help me hit my serve better.

Storm, keep in mind in these images that the yellow balls you see (on one top of the other) are from the toss. The ball is coming down from the toss, and then it is hit, and as a result you see the ball now moving forward.

Yeah I figured that.

One other thing that you are confusing. Even though the racquet is traveling upwards, this does not mean the strings are hitting the bottom of the ball. The racquet face travels upwards, however before impact the racquet has reached perpendicular and hits the **back** of the ball, not the bottom. This is why the ball moves forward and down, and not "up". Of course, as the article points out, there is gravity, drag, etc that also come into play.

Right, but in the dot diagram the ball is hit after the racquet finds its peak, meaning the racquet face must be facing ever so slightly downward when the ball leaves the strings. At least that's what I'm proposing.

Then again if everyone had to understand this to be able to serve well, everybody would suck at tennis.

[nousername]

sureshs, you are not visualizing where the server's feet are, IMO. If you think about the line from the tip of the racquet to the tip of the toes, it "leans" into the court. Therefore, in relation to the line of the body, Venus is still hitting UP on the ball.

Not if you want the serve to go IN.

I remember an article in (World Tennis? Tennis?) many years ago, where they showed 7'2" Wilt Chamberlin (sp?) at the Baseline with racquet extended and a straight line drawn on the photo to the other side. The ball would still have gone OUT. (Of course, the article didn't account for gravity, drag and spin.)

If you want your "Flat" serve to go IN, you must hit UP on the ball.

- KK
part in bold it KEY. for me, it is the "missing link".

but also, i now agree, in part, with sureshs, he's right that relative to the flat earth, the racket tip *may* be going down at contact. but KK has quite precisely pointed out topspin is still generated ... maybe that is all sureshs was saying all along ... if so, sorry.

BUT the key part about "hitting up", is all in reference to dispel the notion that good "flat" serves are flat. they are not, they have topspin. and even the Venus Williams serve analyzed above has topspin ... EVENTHOUGH the racket tip is moving down AND the racket face is pointing down.

thanks KK for pointing this out. (not sure i agree with your with the other stuff ... too wishy-washing. not solid enough.)

Define "hitting up".

If the ball is compressed against the strings and the racquet face is facing down, is that hitting up? The strings are a trampoline. What you're admitting is that in every serve the strings are indeed facing down when the ball leaves the racquet. If that's "hitting up" then this is only an issue of semantics, but I cannot imagine how spin is what brings the ball down in a flat serve.

Ultimately, you're not hitting up or down. The racquet is being swung in an elliptical path and the ball leaves that ellipsis tangentially.
as a continuation of my comments to KK above, i define "hitting up on a serve" as --> "any stroke path that generates topspin due to serve contact".

that's it ... we who argue for (well, at least me) "hitting up" are merely trying get people to understand the benefits of topspin on ALL serve types. and to show that pros hit with topspin on ALL serves.

So if you do believe/agree with that, summarized here below:

1) topspin is good on serves, even flat serves
2) pros hit all serves with some amount of topspin

then, to me, a good conclusion is:

--> try to hit with topspin ... then if that is your goal .... how to accomplish it? is it better to think about "hittin down" or "hitting up"?

(side note: you cannot say "you're not hitting up or down" based on your argument. b/c we are talking about the tiny time interval during and around contact. that's all we care about. in that time interval it is VALID to make linearization assumtptions about the stroke path (i.e. we can assume the stroke is following a straight line just around the time at impact.) linearization is common in engineering... i say that so you don't fight the notion of linearization. )

--

don't know you don't like the concept of spin bringing in a flat serve??? here's what brings in a "flat" serve: gravity and spin. AND gravity is assisted by the horizontal deceleration due to drag, b/c that give gravity more time to due it's work.

[stormholloway]

^^^Disagree.

As you can see from the Venus diagram, the ball leaves the racquet immediately going down. Gravity could not have affected it to this degree. That'd be like saying if I threw a ball up it would immediately go down. I do contend that at the moment the ball leaves the strings the racquet is facing slightly downward and the diagram above confirms this.

I agree that all flat serves have topspin. The only possible way to hit a ball with zero spin would be if the racquet hit the ball in a completely linear, non-rotational manner.

[Kaptain Karl]

... the highest point has just been crossed when the ball is hit....I thought so.... You are looking at the same vids and "seeing" stuff which is not there.

You are not taking parallax into account: In those seconds you specified, Nadal's strings are making contact "just" before they reach maximum swing height. Since the camera angle is not at right angles to his swing path, you are missing this fact. (He's swinging toward the camera on an oblique angle ... your perspective is parallax.)


Not only that, the racquet has reached its heighest point between the two blue dots and is starting down as it hits the ball.Wrong. Already addressed this by Venus' body position. In relation to where her feet are, she's still hitting UP.



I would also like to see what he is talking about when he says one can hit the ball down between 12-3 and impart topspin.Yeah, but I'm betting we'll never see that clip.

- KK

[stormholloway]

I thought so.... You are looking at the same vids and "seeing" stuff which is not there.

You are not taking parallax into account: In those seconds you specified, Nadal's strings are making contact "just" before they reach maximum swing height. Since the camera angle is not at right angles to his swing path, you are missing this fact. (He's swinging toward the camera on an oblique angle ... your perspective is parallax.)

Yes but where is the racquet face when the ball leaves the strings? That's more important.

[sureshs]

IYou are not taking parallax into account: In those seconds you specified, Nadal's strings are making contact "just" before they reach maximum swing height.

If that was the case, with the tremendous swing speed he generates, the ball would have left instantaneously in an upward trajectory, in spite of gravity. It would not be going horizontal or slightly below it.

[Sublime]

The Sampras serves and Venus serves are very different in respect to the racket tip moving up at impact.

Doesn't Venus have a pretty low first serve percentage? Could this be a contributing factor?

[sureshs]

Yes but where is the racquet face when the ball leaves the strings? That's more important.

I wouldn't say it is the most important factor, but it is a factor.

Your earlier comments about the "time" it would take for drag and gravity to have effect are more interesting. I said at that time it is a non-issue because they act all the time. But what is interesting from Nadal's video is how the ball goes almost horizontally or slightly down and starts dipping only after crossing the second lampost. Gravity, drag and spin will bring it down eventually, but just after impact, we would expect to see the ball moving upwards if it was really hit upwards with Nadal's racquet head speeds. We would be seeing a more parabolic trajectory like a baseball or a soccer ball. We see no such thing.

[LeftySpin]

I don't know about "hitting up" but when you're serving you're definatly suppose to accelerate up and not try to swing down

[sureshs]

Here is an example of an ordinary dude. Step frame by frame and see how the racquet motion changes to downwards just before impact.

http://revver.com/video/641083/flat-serve-oliver-3q/

[sureshs]

I don't know about "hitting up" but when you're serving you're definatly suppose to accelerate up and not try to swing down

If you continue to accelerate up and swing up, guess how the ball path would look when it leaves the strings? Like a soccer ball or a golf ball. And it does happen on second kick serves.

[sureshs]

Here is something I am throwing out there for you guys to think about: Ever seen a lacrosse player grabbing the ball and tossing it? The more I see videos, specially like the last one I posted, I suspect the ball is dwelling on the strings as it is being "caught" and flung downwards on these serves.

[stormholloway]

I wouldn't say it is the most important factor, but it is a factor.

I think where the racquet faces when the ball leaves the strings is more important than when the ball first hits the strings. Then again, it could be somewhere in between, perhaps when the ball is most compressed.

Your earlier comments about the "time" it would take for drag and gravity to have effect are more interesting. I said at that time it is a non-issue because they act all the time. But what is interesting from Nadal's video is how the ball goes almost horizontally or slightly down and starts dipping only after crossing the second lampost. Gravity, drag and spin will bring it down eventually, but just after impact, we would expect to see the ball moving upwards if it was really hit upwards with Nadal's racquet head speeds. We would be seeing a more parabolic trajectory like a baseball or a soccer ball. We see no such thing.

Agreed. The ball should initially go upward, but it does not. While I believe that all serves have spin, flat serves really are... rather flat.

[sureshs]

I think where the racquet faces when the ball leaves the strings is more important than when the ball first hits the strings. Then again, it could be somewhere in between, perhaps when the ball is most compressed.



Agreed. The ball should initially go upward, but it does not. While I believe that all serves have spin, flat serves really are... rather flat.

See my last video. The ball is very emphatically on its way down from impact. No instantaneous upward motion followed by a gradual drop.

And I don't think this is just for flat serves. A serve hit down with sidespin will have sidespin of course, and some of that becomes topspin after bounce.

[nousername]

^^^Disagree.

As you can see from the Venus diagram, the ball leaves the racquet immediately going down. Gravity could not have affected it to this degree. That'd be like saying if I threw a ball up it would immediately go down. I do contend that at the moment the ball leaves the strings the racquet is facing slightly downward and the diagram above confirms this.

I agree that all flat serves have topspin. The only possible way to hit a ball with zero spin would be if the racquet hit the ball in a completely linear, non-rotational manner.
i completely agree that the trajectory was DOWN. i think we both agree that the intial trajectory off the racket is always perpendicular to the face of the racket.

but don't you also agree that if you draw a straight line off the initial trajectory, of the venus serve diagram, that the ball would go long???

my point was that gravity and spin provide the primary effect to bring serves into the service box.

YES, the serve is angled downward initially, but that angle alone won't bring it IN.

[nousername]

Agreed. The ball should initially go upward, but it does not. While I believe that all serves have spin, flat serves really are... rather flat.
sampras flat serve has ~2500 rpms of topspin, about the same as average pro's forehands.

his kick serve had ~4500 rpms of topspin.

IMHO that amount of action is the one of the 2 reasons sampras's serve was so good... the other being the difficulty to read his serve.

(also, the reason it seems pro's serves hit so high up the back wall is due to the spin, not the pace.)

[sureshs]

YES, the serve is angled downward initially, but that angle alone won't bring it IN.

It won't. Gravity and air drag help with it.

And if the serve is angled downward initially (and gravity also acts down of course), could it have been hit up? Think about it. It can, if gravity was so powerful that the force with which it is being struck is negligible compared to it. Like dropping a soccer ball and blowing air upwards through your mouth as it comes down. It won't make any difference to the downward movement. Can the same thing happen in tennis with the racquet head acceleration that is present? No. A ball heading down initially has been hit down initially.

[bhupaes]

After watching a bunch of slow motion videos from behind the server, I think I understand what's going on. Let me try to explain.

Remember, we had a discussion recently as to how there is an angle between the racquet and the forearm when contact is made? The racquet is not quite perpendicular to the ground at contact point - the head tilts a little to the left for a righty, if you watch from behind. Also keep in mind that the racquet head motion is circular, going from left to right, so as it progresses to the right after contact, it actually rises. This is offset a little by the fact that at this point, most servers are reaching forward, and when watched from the side, the racquet seems to be tilting forward. The net effect of these motions, however, is that at contact time, the racquet head actually rises a little at the contact point. This is hard to see because the head is near the apex and is moving very fast, and starts coming down very soon after contact.

Don't take my word for it, go see the videos like I did - and don't let your boss catch you at it. :)

[sureshs]

The net effect of these motions, however, is that at contact time, the racquet head actually rises a little at the contact point. This is hard to see because the head is near the apex and is moving very fast, and starts coming down very soon after contact.

Since the ball does not know all this, it should also rise after contact if it is being hit slighly upward at contact, specially if the racquet is moving very fast and imparting a lot of force. In fact, even a slight upward direction for these enormous forces should result in the ball shooting up rapidly at impact.

But it doesn't in those videos. Everything else is just our imagination. Let us just go by what the ball is doing - which is moving down immediately on impact (in some scenarios).

[bhupaes]

Since the ball does not know all this, it should also rise after contact if it is being hit slighly upward at contact, specially if the racquet is moving very fast and imparting a lot of force. In fact, even a slight upward direction for these enormous forces should result in the ball shooting up rapidly at impact.

But it doesn't in those videos. Everything else is just our imagination. Let us just go by what the ball is doing - which is moving down immediately on impact (in some scenarios).

Keep in mind that this is not a direct, head-on collision. It is a glancing blow, much like the precisely engineered collision between two billiard balls. It is the same reason why a heavy topspin forehand doesn't result in the ball going straight up, and can have a flat trajectory.

[Kaptain Karl]

sureshs, you persist in attempting to sway empirical evidence with your own pretext. You are not being an "honest broker" in this discussion. The question posed by the OP was "Do you hit UP on your serve?" Not, "Where is the ball going immediately after impact?"

ALL the slow-mo analyses have shown players hit UP on the Serve to get the ball where they intend. (Forgetting the "Hacker's" Frying Pan Serve of a ball at about nose height, where they are imparting backspin on the serve to get air pressure to "float" it into the Service Box.) I am focusing on Tennis Players who know what they are doing -- who have competence....

If that was the case, with the tremendous swing speed he generates, the ball would have left instantaneously in an upward trajectory, in spite of gravity.Incorrect. Your presumption (pretext) is not accurate.

... what is interesting from Nadal's video is how the ball goes almost horizontally or slightly down and starts dipping only after crossing the second lampost. Gravity, drag and spin will bring it down eventually, but just after impact, we would expect to see the ball moving upwards if it was really hit upwards with Nadal's racquet head speeds.More pretext. (False.)

Here is an example of an ordinary dude. Step frame by frame and see how the racquet motion changes to downwards just before impact.Again, you are "seeing" stuff which isn't there. I see a Slice Serve. At impact this guy's strings are moving across the ball's equator; not down. (And you are still ignoring the fact that average-to-good servers are "leaning" into the toss. Their swings are still UP in relation to their foot position.) I wonder why you consistently ignore this. (Oh! Maybe it's because it shows the error of your pretext.)




After watching a bunch of slow motion videos from behind the server, I think I understand what's going on. Let me try to explain.

Remember, we had a discussion recently as to how there is an angle between the racquet and the forearm when contact is made? The racquet is not quite perpendicular to the ground at contact point - the head tilts a little to the left for a righty, if you watch from behind. Also keep in mind that the racquet head motion is circular, going from left to right, so as it progresses to the right after contact, it actually rises. This is offset a little by the fact that at this point, most servers are reaching forward, and when watched from the side, the racquet seems to be tilting forward. The net effect of these motions, however, is that at contact time, the racquet head actually rises a little at the contact point. This is hard to see because the head is near the apex and is moving very fast, and starts coming down very soon after contact.Yes! Thanks for contributing. It's been like posting to a WALL lately....

- KK

[sureshs]

http://www.wikihow.com/Hit-a-Flat-Serve-in-Tennis

"Tips You should try and hit down on the ball."

[Kaptain Karl]

Since the ball does not know all this, it should also rise after contact if it is being hit slighly upward at contact, specially if the racquet is moving very fast and imparting a lot of force. In fact, even a slight upward direction for these enormous forces should result in the ball shooting up rapidly at impact.No. It depends on the contact point on the ball and the vector. (I'm pretty sure that's the correct term.)

Keep in mind that this is not a direct, head-on collision. It is a glancing blow, much like the precisely engineered collision between two billiard balls. It is the same reason why a heavy topspin forehand doesn't result in the ball going straight up, and can have a flat trajectory.BINGO!!!

- KK

[sureshs]

sureshs, you persist in attempting to sway empirical evidence with your own pretext. You are not being an "honest broker" in this discussion. The question posed by the OP was "Do you hit UP on your serve?" Not, "Where is the ball going immediately after impact?"


Unlike you, I know enough to understand that they are not unrelated issues.

And please cut down on the personal insults. If you feel you are talking to a wall, kindly exit the thread. There is no reason to heap insults on posters here. It is difficult to imagine you are a moderator here, but that has been discussed before.

Once again, I have no personal issues with you in this thread and would like for you to stop the insults.

Thanks in advance.

[sureshs]

https://www.tennisplayer.net/bulletin/showthread.php?t=1267

" #3 03-21-2009, 10:23 AM
johnyandell
Senior Member Join Date: Feb 2005
Posts: 1,635



--------------------------------------------------------------------------------

I cannot prove this quantitatively but do believe the racket tip is rising all the way until contact. BUT one thing we did see in our trajectory studies was that the ball actuallly leaves the strings on a slight downward path. That is because the angle of the racket face is tilted slightly forward--actually this is the forward angle of the entire arm. In terms of a feeling it's all up--just my opinion."

[J011yroger]

I don't really understand why everyone is trying to convince sureshs.

It is obvious that he is not going to listen to any opinion that doesn't correlate with his own.

If you are doing it for the benefit of other posters, then all you need to do is say your part, and then you are done. People will listen to whomever they are going to listen to after reading both sides, and deciding whom they agree with.

J

[sureshs]

Keep in mind that this is not a direct, head-on collision. It is a glancing blow, much like the precisely engineered collision between two billiard balls. It is the same reason why a heavy topspin forehand doesn't result in the ball going straight up, and can have a flat trajectory.

A flat serve is not a glancing blow.

A topspin forehand is hit low to high. One reason it may go flat is because the incoming topspun ball tends to drag down on the strings, while the player is attempting to counteract it. For the other reason, see below.

I already addressed this issue before - with the example of the ping pong video game. The ball is hit tangentially up and the ball goes straight or down, isn't it? I have also pointed out several times that this kind of glancing blow can only happen with a tangentially upward movement of the racquet - like your forehand topspin example. The serve is NOT that type of motion. The face does not come up tangentially on the ball from below for flat serves.

[sureshs]

Check this out. Flat Murray serve (no "glancing" blow here). Turn on the high quality option and step. The ball is contacted at the highest point of the serve and is hurled downwards.

http://videosportsanalysis.blogspot.com/2009/03/andy-murrays-tennis-serve.html

[J011yroger]

I know what andy murrays serve looks like. It is yours that I am interested in.

J

[Kaptain Karl]

Unlike you, I know enough to understand that they are not unrelated issues.

Once again, I have no personal issues with you in this thread and would like for you to stop the insults.My observations were no more insults than your own opening line to me. I am free to observe you don't know what you are posting about.



I know what andy murrays serve looks like. It is yours that I am interested in.Yes, sureshs. Get out there with your camera, please.

- KK

[drakulie]

My observations were no more insults than your own opening line to me. I am free to observe you don't know what you are posting about.

I agree.


Yes, sureshs. Get out there with your camera, please.

- KK

I would really like to see what he is talking about when he says hitting down from 12-3 to impart top spin.

[nousername]

A flat serve is not a glancing blow.

A topspin forehand is hit low to high. One reason it may go flat is because the incoming topspun ball tends to drag down on the strings, while the player is attempting to counteract it. For the other reason, see below.

I already addressed this issue before - with the example of the ping pong video game. The ball is hit tangentially up and the ball goes straight or down, isn't it? I have also pointed out several times that this kind of glancing blow can only happen with a tangentially upward movement of the racquet - like your forehand topspin example. The serve is NOT that type of motion. The face does not come up tangentially on the ball from below for flat serves.
what are you talking about?

"glancing blow" ... it's a matter of scale. you cannot just post a video, and say "it doesn't look glancing to me". contact happens in a very small time interval, and for the serve the only part that matter is that tiny window of time when the ball is on the stringbed.

and even the video of murray's serve you posted I can assure you is glancing upward on the ball to impart topspin.

also, do you realize that even a heavy topspin forehand is mostly a forward motion with a small upward component?

lastly, you have no idea how to use the word "tangentially" so please stop.
do you realize that the face of the racket is a tangent plane to the ball ... and each any every shot mankind has ever hit in tennis?

[sureshs]

what are you talking about?

"glancing blow" ... it's a matter of scale. you cannot just post a video, and say "it doesn't look glancing to me". contact happens in a very small time interval, and for the serve the only part that matter is that tiny window of time when the ball is on the stringbed.

and even the video of murray's serve you posted I can assure you is glancing upward on the ball to impart topspin.

also, do you realize that even a heavy topspin forehand is mostly a forward motion with a small upward component?

lastly, you have no idea how to use the word "tangentially" so please stop.
do you realize that the face of the racket is a tangent plane to the ball ... and each any every shot mankind has ever hit in tennis?

If it was a glancing blow, the ball would be partially obscured by the strings looking from the side. From the video, it is clear that there is an unobstructed view of the ball and no sideways hit on it. It is a head-on collision.

As I have repeatedly said, a flat serve does not have the same mechanics as a forehand.

Looks like you want to assure me there is no glancing blow based on what? The video, or speculation.

And I guess you have never heard of the overhead smash? Is the racquet face delivering a "glancing blow"?

Of course every shot is hit with a tangent plane - that is how a sphere and a plane interact. The question is the position of the plane wrt the eventual path of the ball. If you hit a billiard ball head on, the little plane on the tip of the cue also hits the ball at a tangent plane, however small. Can't you see that when we speak of a tangential hit, we are talking about how the cue goes straight but the ball goes to the side and not a head-on hit? Are you not capable of understanding this simple usage of language?

Next time please study the videos carefully.

[sureshs]

Just now saw Federer slam a flat wide one at Roddick. It occured to my why the geometry calculations are wrong. The distance is not service line to baseline, but a greater diagonal distance within the service box, plus the stepping into the court.

[J011yroger]

I would really like to see what he is talking about when he says hitting down from 12-3 to impart top spin.

The best I can reason he is talking about a topspin/slice, or hard slider.

I don't know if it is something you have in your toolbox, but it is hit like a slice serve, except instead of going from the middle of the ball to 3o'clock, you go to 1:30ish.

As opposed to a kicker or topspin serve where you are attacking the bottom of the ball to the middle, this one you are attacking middle to top.

J

[Ballinbob]

I suck at this physics stuff so I'm not even going to take a side.

However, doesn't it tell you something sureshs that everyone is disagreeing with you? It's not bad to be wrong, so just telling you that. I've been wrong a million times.

Maybe it's best that you just drop it? It's your choice. But as an outside observer it seems that everyone is against you...

I'm not saying anyone is right or wrong, but I'm just not seeing this going anywhere

[sureshs]

"The research also shows that as important, or more important than the total amount of spin is the type of spin. Of particular importance is the topspin component. First, it’s important to realize that a pure topspin serve is a myth. The research conclusively demonstrates that the majority of the spin on all serves is sidespin."

http://www.tennis.com/yourgame/instructionarticles/visuals/visuals.aspx?id=109012


So don't go around saying Sampras' "topspin" was 3000 to 5000 rpm. Most of it is sidespin, which is a sideswipe on the ball.

[sureshs]

The best I can reason he is talking about a topspin/slice, or hard slider.

I don't know if it is something you have in your toolbox, but it is hit like a slice serve, except instead of going from the middle of the ball to 3o'clock, you go to 1:30ish.

As opposed to a kicker or topspin serve where you are attacking the bottom of the ball to the middle, this one you are attacking middle to top.

J

Thank you. A person with an open mind will always get it, while the closed-mind parrots will not.

[maverick66]

i think you guys are overcomplicating tennis. seriously if someone pulled out all these charts to show me how to hit a serve i would walk off the court laughing. whatever happened to actually hitting a ball instead of annalyzing every little angle.

[Ballinbob]

i think you guys are overcomplicating tennis. seriously if someone pulled out all these charts to show me how to hit a serve i would walk off the court laughing. whatever happened to actually hitting a ball instead of annalyzing every little angle.

omg Agreed!!

[sureshs]

IHowever, doesn't it tell you something sureshs that everyone is disagreeing with you?

They also said the racquet face always points up at contact. Then they came around.

The righteous are always persecuted. Such is the way of the world.

[Ballinbob]

They also said the racquet face always points up at contact. Then they came around.

The righteous are always persecuted. Such is the way of the world.

well alright, I'll let you go at it then. Goodluck, seems like you have a tough crowd to convince lol

I would try and pick a side but this is too much physics for me:) I just hit the ball, I have no idea if I'm hitting the ball up or down

[J011yroger]

I just hit the ball, I have no idea if I'm hitting the ball up or down

As long as it goes like hell, and lands in the box once in a while, you are golden.

J

[drakulie]

The best I can reason he is talking about a topspin/slice, or hard slider.

I don't know if it is something you have in your toolbox, but it is hit like a slice serve, except instead of going from the middle of the ball to 3o'clock, you go to 1:30ish.

As opposed to a kicker or topspin serve where you are attacking the bottom of the ball to the middle, this one you are attacking middle to top.

J


I understand what you are saying, but he is saying from 12 to 3. He states he is hitting down on the ball. That means he is brushing down on the back of the ball from the 12 o'clock position to 3 o'clock, and somehow getting top spin. :shock: again, I want to see video of this. Maybe this is why he is having problems serving with the kps88. ????

[Ballinbob]

As long as it goes like hell, and lands in the box once in a while, you are golden.

J

Yeah I'm happy with my serve, not complaining. I don't know if it goes like hell but it does the job at my level lol

I'm dead serious though, I read 4 pages of this thread and I have a headache. I think I'll have to call it a night lol. I'll be in physics senior year, I'll join you guys then:)

[J011yroger]

I understand what you are saying, but he is saying from 12 to 3. He states he is hitting down on the ball. That means he is brushing down on the back of the ball from the 12 o'clock position to 3 o'clock, and somehow getting top spin. :shock: again, I want to see video of this. Maybe this is why he is having problems serving with the kps88. ????

Dude. . . Yea. . . I have no idea what he is talking about. It is just that serve is the closest thing I can think of to an actual legitimate serve which I can remotely connotate with what he wrote.

Your guess is as good as mine.

That is why I asked him to put up the video.

J

[J011yroger]

Yeah I'm happy with my serve, not complaining. I don't know if it goes like hell but it does the job at my level lol

I'm dead serious though, I read 4 pages of this thread and I have a headache. I think I'll have to call it a night lol. I'll be in physics senior year, I'll join you guys then:)

Just keep after it, and get help when you struggle.

I will try to get some footage of me playing S&V on Friday, or over the weekend. I know you asked about that.

I always deliver, just sometimes it takes me a little while :)

J

[mtommer]

I understand what you are saying, but he is saying from 12 to 3. He states he is hitting down on the ball. That means he is brushing down on the back of the ball from the 12 o'clock position to 3 o'clock, and somehow getting top spin. :shock: again, I want to see video of this. Maybe this is why he is having problems serving with the kps88. ????

I'm wondering if he means 3 o'clock is facing into the court and 9 o'clock would be facing towards the server. How someone could generate pace or serve how people do so now, though, is beyond me.

[J011yroger]

I'm wondering if he means 3 o'clock is facing into the court and 9 o'clock would be facing towards the server. How someone could generate pace or serve how people do so now, though, is beyond me.

It is tough, because you are trying to put a complicated motion into words, and use a 2D clock face, to replicate a 3D tennis ball.

J

[Ballinbob]

Just keep after it, and get help when you struggle.

I will try to get some footage of me playing S&V on Friday, or over the weekend. I know you asked about that.

I always deliver, just sometimes it takes me a little while :)

J

I wish I was the same way:( I need help with my volleys but I haven't posted a vid yet. I have to get on that ASAP. Just kinda hard with all the snow we're getting

And I'm looking foward to those vids, I'll see if I can learn a thing or two. I saw that vid of yours where you hit that kick serve over the back curtain, that was riddiculous! Especially if you use that serve when S&Ving, that's scary:shock:

[J011yroger]

I wish I was the same way:( I need help with my volleys but I haven't posted a vid yet. I have to get on that ASAP. Just kinda hard with all the snow we're getting

And I'm looking foward to those vids, I'll see if I can learn a thing or two. I saw that vid of yours where you hit that kick serve over the back curtain, that was riddiculous! Especially if you use that serve when S&Ving, that's scary:shock:

Well I have a really big ground game, so if someone hits a weak return, and I volley it away, or I smoke a forehand winner, it is basically the same thing, so it doesn't matter if I stay back or come in.

What S&V does for me, is it eliminates my opponent blocking my serve back deep and starting the point neutrally. If I demonstrate that I can and will S&V then they *have* to swing at their returns, which just gives me free points as they make more errors.

That is my theory and why I devote so much effort into working on it. It is still very much a work in progress, but I see potential there. Lots of potential.

When you take you video it helps if you can take from both angles, like this one of my volleys.

http://vimeo.com/3515029

I personally like the rear view for point play, so I can see how I construct the points, how and where I approach, and so forth, and I like the front 3/4 view for seeing exactly what is going on with my feet and volleys.

J

[gzhpcu]

See my last video. The ball is very emphatically on its way down from impact. No instantaneous upward motion followed by a gradual drop.

And I don't think this is just for flat serves. A serve hit down with sidespin will have sidespin of course, and some of that becomes topspin after bounce.
Stop talking about topspin after the bounce. This is totally irrelevant. We are only talking about the flight path of the ball from impact with the racket to impact with the ground, since the title of the thread concerns the racket head impact.

[maverick66]

you drop your hand down on your backhand side other than that pretty good.

[gzhpcu]

"The research also shows that as important, or more important than the total amount of spin is the type of spin. Of particular importance is the topspin component. First, it’s important to realize that a pure topspin serve is a myth. The research conclusively demonstrates that the majority of the spin on all serves is sidespin."

http://www.tennis.com/yourgame/instructionarticles/visuals/visuals.aspx?id=109012


So don't go around saying Sampras' "topspin" was 3000 to 5000 rpm. Most of it is sidespin, which is a sideswipe on the ball.
What you fail to understand is that there all spin is a combination of pure topspin and pure slice (sidespin) and that a pure topspin or slice serve does not exist. You just have varying combinations of the above, but that you need a topspin component to pull the serve down. Sidespin does not pull the ball down.

[drakulie]

I'm wondering if he means 3 o'clock is facing into the court and 9 o'clock would be facing towards the server.

OK. This is funny. Let's say what you wrote is what he meant.

The that would mean his serve would come back towards him, since he say he is hitting down on the ball.

In other words, his swing would be coming towards the ground, his racquet face would hit the ball at 12 o'clock, and brush down towards the 3 o'clock (which is facing the returner), which would result the ball hitting him smack in the face. LMAO!!

[nousername]

"The research also shows that as important, or more important than the total amount of spin is the type of spin. Of particular importance is the topspin component. First, it’s important to realize that a pure topspin serve is a myth. The research conclusively demonstrates that the majority of the spin on all serves is sidespin."

http://www.tennis.com/yourgame/instructionarticles/visuals/visuals.aspx?id=109012


So don't go around saying Sampras' "topspin" was 3000 to 5000 rpm. Most of it is sidespin, which is a sideswipe on the ball.
you are right. it is not pure topspin. i should not have said that.

but sampras's flat serve does have 2500 rpms of spin ... with a sidespin and topspin component. for a flat, it will be mostly topspin .... just guessing, but probably an 80%/20% split.

when you most of it is sidespin, that is what is called a slice serve. sampras also uses that serve.

[gzhpcu]

To understand the Magnus effect and some physics on applying various types of spin on a tennis ball, look at this article Will posted on fyb:

http://www.fuzzyyellowballs.com/articles/index.php/view/969/106/The_Physics_of_Topspin_on_a_Tennis_Ball

Most right handed tennis players will hit a slice serve by striking (and brushing across) the right side of the tennis ball as seen from behind. The racket moves from the back to the front of the ball along its right side, and this sets the ball spinning from left to right (again as seen from behind). In this case, the Magnus effect will cause the ball to curve leftward as it travels through the air towards the opponent’s service box.

When a tennis player hits a kick serve, he imparts a combination of sidespin and topspin to the tennis ball. This is accomplished by brushing up across the back of the tennis ball (to impart topspin) and across the side of the ball at the same time (to impart sidespin). The result of adding these two spins together is that the ball spins on an axis that is diagonal to its direction of travel.

[bhupaes]

Check this out. Flat Murray serve (no "glancing" blow here). Turn on the high quality option and step. The ball is contacted at the highest point of the serve and is hurled downwards.

http://videosportsanalysis.blogspot.com/2009/03/andy-murrays-tennis-serve.html

Suresh, you need to see either the front view, or even better, the view from behind, of Murray serving. The view from the side can be deceptive because of the parallax effect (as KK correctly pointed out), which obscures the sideways and upward motion of the racquet head.

[stormholloway]

i completely agree that the trajectory was DOWN. i think we both agree that the intial trajectory off the racket is always perpendicular to the face of the racket.

but don't you also agree that if you draw a straight line off the initial trajectory, of the venus serve diagram, that the ball would go long???

my point was that gravity and spin provide the primary effect to bring serves into the service box.

YES, the serve is angled downward initially, but that angle alone won't bring it IN.

I agree with this. It was the only point I was trying to make.

[sureshs]

Suresh, you need to see either the front view, or even better, the view from behind, of Murray serving. The view from the side can be deceptive because of the parallax effect (as KK correctly pointed out), which obscures the sideways and upward motion of the racquet head.

There is a very poor quality Roddick front view video, you can search for it.

Any significant upward motion at such racquet head speeds will result in the ball moving up immediately after impact, whether it also happens to be to the side is not the issue. Whichever direction it is moving in the plane parallel to the ground, it will still have a vertical component of movement which will be much greater than gravity. This will never allow the ball to start descending right from impact. You need to separate what happens parallel to the ground plane from what happens parallel to the vertical axis.

Glancing blow, head-on blow, all blows - significant upward momentum transferred to the ball by swinging up at high speeds will result in short-term upward movement, not downward. Ball does not understand these terms - it only knows the 3 components of momentum, gravity and air drag.

[drakulie]

Sampras top spin serve:. Racquet still going up after impact, and ball going down immediately after impact:

http://www.tennisserver.com/set/images/set_03_09/Set_1860.jpg


still await an explanation of what you were talking about when saying hitting down from 12 to 3 to achieve top spin.

[Sublime]

Any significant upward motion at such racquet head speeds will result in the ball moving up immediately after impact, whether it also happens to be to the side is not the issue.

This is absolutely not true. The motion of the racket face will have a very minor effect on the trajectory of the ball, even if the racket is swung at MACH 4. Even a slight, 1 or 2 degree, closed racket face will overcome the impact of the racket face motion on the trajectory and the ball will go immediately down.

Not to muddy the water too much, but something else to think about. With the ball dropping at impact (as it is with just about every pro serve), even if the motion of the racket face is a little downward, you could still end up with a slight topspin component, because the relative speed of the racket face to the ball is still upward.

[stormholloway]

That's the point: the racquet face is always slightly closed at impact.

[sureshs]

Sampras top spin serve:. Racquet still going up after impact, and ball going down immediately after impact:

http://www.tennisserver.com/set/images/set_03_09/Set_1860.jpg


still await an explanation of what you were talking about when saying hitting down from 12 to 3 to achieve top spin.

I think jolly already explained it to you.

The above is interesting. Sampras hits a top spin kick serve by brushing up against the ball at tremendous speeds, and the ball starts going downwards immediately. Even club players hit top spin kick serves which arc upwards before they come down. That is the whole point really.

Tells you something about the credibility of the study.

[sureshs]

This is absolutely not true. The motion of the racket face will have a very minor effect on the trajectory of the ball, even if the racket is swung at MACH 4. Even a slight, 1 or 2 degree, closed racket face will overcome the impact of the racket face motion on the trajectory and the ball will go immediately down.

Not to muddy the water too much, but something else to think about. With the ball dropping at impact (as it is with just about every pro serve), even if the motion of the racket face is a little downward, you could still end up with a slight topspin component, because the relative speed of the racket face to the ball is still upward.

Have you seen topspin or twist serves being hit? Even at the club level, the ball goes up before it comes down.

The ball does not know that the racquet face is closed. It only knows it was hit up in a glancing fashion.

And of course none of this pertains to flat serves where the ball is being smacked down. Face is moving down and is also closed.

Your last point is so good I will address it separately.

[sureshs]

Not to muddy the water too much, but something else to think about. With the ball dropping at impact (as it is with just about every pro serve), even if the motion of the racket face is a little downward, you could still end up with a slight topspin component, because the relative speed of the racket face to the ball is still upward.

That is what I meant by saying topspin can be produced by hitting down on the ball.

You hit it about the same axis as usual, in the same rotational direction as usual, but from the opposite side.

Jolly understood it. You came up with it yourself. Drakulie is trying to understand it.

People are slowly getting what I am saying.

[sureshs]

Apart from the obvious reasons of ignoring the distance into court, and diagonal distances in the opposite serving box, the fundamental mistake being made is to draw straight lines to illustrate the path of the ball from point A to point B. The ball is shown as if it fired downward from A to B. In reality, the ball is hit in a direction of slightly below horizontal, and follows a parabolic trajectory as described for projectile motion - probably more complicated as air drag and not just gravity need to be taken into account. The "upward bulge" of the parabola is what helps the ball clear the net. In the Nadal serve video I posted, you can see how the ball is going almost horizontal and then slowly starting to curve down into the distance.

[bhupaes]

Suresh, I think you are intellectualizing it incorrectly, and (unconsciously) seeing only what you want to see in the videos. I have had the same problem in other aspects of tennis before, because I was laboring with the wrong model in my head as a result of my not having enough feel for that aspect of tennis at that time. As I got better, I changed my views on many aspects of the game.

So let us, like the cultured gentlemen we are, agree to disagree. :)

[drakulie]

I think jolly already explained it to you.




Jo11y, with all due respect to him, gave a guess of what you are talking about.

You stated you could hit a top spin serve by hitting down on the ball and brushing it from 12 to 3. Please explain.

[drakulie]

I think jolly already explained it to you.

The above is interesting. Sampras hits a top spin kick serve by brushing up against the ball at tremendous speeds, and the ball starts going downwards immediately. Even club players hit top spin kick serves which arc upwards before they come down. That is the whole point really.

When club players are actually making the ball move with their top spin serves like sampras does, then you may have a point. but hitting the ball up in the air to make it bounce higher does not equate to a top spin serve.

Tells you something about the credibility of the study.

Yes it does. It shows you are incorrect.

[sureshs]

When club players are actually making the ball move with their top spin serves like sampras does, then you may have a point. but hitting the ball up in the air to make it bounce higher does not equate to a top spin serve.


Agree. You need to add spin to it by brushing up on it. Sampras adds more spin with more force upwards brushing it. Yet for club players the ball goes up spinning while for Sampras it heads downwards to the side. Doesn't make sense.

[sureshs]

Jo11y, with all due respect to him, gave a guess of what you are talking about.

You stated you could hit a top spin serve by hitting down on the ball and brushing it from 12 to 3. Please explain.

Not from 12 to 3, but someplace between 12 to 3 about the axis passing passing thru it. Jolly mentioned 1:30 as an example.

Did you really think I was talking about hitting from 12 to 3? Read that post carefully.

[drakulie]

^^^I'm reading into it just how you stated.

BTW, you can't hit a ball at "1:30".

the "1" is near the 12 o'clock position, and the "30" is 6 o'clock. So are you saying, as Jo11y suggests, you are hitting the ball in two places simultaneaously?? :shock:

[Ballinbob]

Well I have a really big ground game, so if someone hits a weak return, and I volley it away, or I smoke a forehand winner, it is basically the same thing, so it doesn't matter if I stay back or come in.

What S&V does for me, is it eliminates my opponent blocking my serve back deep and starting the point neutrally. If I demonstrate that I can and will S&V then they *have* to swing at their returns, which just gives me free points as they make more errors.

That is my theory and why I devote so much effort into working on it. It is still very much a work in progress, but I see potential there. Lots of potential.

When you take you video it helps if you can take from both angles, like this one of my volleys.

http://vimeo.com/3515029

I personally like the rear view for point play, so I can see how I construct the points, how and where I approach, and so forth, and I like the front 3/4 view for seeing exactly what is going on with my feet and volleys.

J

I'll keep all this in mind when I shoot my vid. I'll try and get more than 1 view for sure.

But I think that's what makes you a really good player Jolly. You have a big ground game but can also S&V profciently. You can attack the net when you need too and can finish points from at net and at the baseline. I'm just a one dimensional S&Ver with below average volleys. I have a decent kick serve that I can place well, which is what is really going for me right now. And lol swinging at your serves wouldn't work unless the guy your playing has amazing timing, which isn't going to happen probably.

Thanks so much for the vid tips though, and good luck with your game and everything:)

[J011yroger]

but can also S&V profciently.

Woah, hey. . . Cart before the horse.

I don't consider myself able to do anything proficiently.

I don't think there is a single aspect of my game that I consider OK, or that I don't want to improve in some way or another.

But yea, I will keep working at it, and will keep everyone posted with my progress. If anyone else wants to get better aswell, then I will do my best to help them along in my journey.

J

[SystemicAnomaly]

http://wings.avkids.com/Tennis/Images/Set_2035.jpg


...

The above is interesting. Sampras hits a top spin kick serve by brushing up against the ball at tremendous speeds, and the ball starts going downwards immediately. Even club players hit top spin kick serves which arc upwards before they come down. That is the whole point really.

Tells you something about the credibility of the study.

I believe that this is a Sampras first serve, not a heavy "topspin" 2nd serve. I would probably not question the credibility of this research study at all. I believe that this study was a collaborative effort with NASA, Cislunar and, possibly, UC Davis. The research team included John Yandell, physicist Dr Howard Brody, Dr Paul Roetert, Dr Jani Pollis, Dr Rabi Mehta and other (http://wings.avkids.com/Tennis/Project/our_team.html) respected researchers (http://wings.avkids.com/Tennis/Project/our_team.html).

wings.avkids.com/Tennis/Project/index.html (http://wings.avkids.com/Tennis/Project/index.html)
wings.avkids.com/Tennis/Project/serve-01.html (http://wings.avkids.com/Tennis/Project/serve-01.html)

.

[SystemicAnomaly]

http://www.wikihow.com/Hit-a-Flat-Serve-in-Tennis

"Tips You should try and hit down on the ball."

Was this written by any recognized authorities on serving? Just a we have unqualified people passing themselves off as experts on Expert Village, probably any fool can post a "how-to" on the site above. Regardless of whether we really hit up on the serve, or hit (slightly) down on the serve, it is "bad" coaching, for most students, to tell them to "try & hit down on the ball". However, it might be a suitable instruction for a few students -- those who consistently hit long or those who hit nothing but "powder puff" serves.


A flat serve is not a glancing blow....

I believe that we've established that there are no "flat" serves. All serves have spin and all serves, to some extent, are "glancing blows".


Check this out. Flat Murray serve (no "glancing" blow here). Turn on the high quality option and step. The ball is contacted at the highest point of the serve and is hurled downwards.

http://videosportsanalysis.blogspot.com/2009/03/andy-murrays-tennis-serve.html

There is a considerable amount of spin on this Murray serve, hence a glancing blow. A Sampras first serve averaged ~2700 rpm with some exceeding 4000 rpm according to one study (http://wings.avkids.com/Tennis/Project/usspin-07.html). In the same study, even the flattest of servers (Chang & Henman) employed ~1600 rpm on first serves. to my mind, these would all be glancing blows.

No, the served is not "hurled downwards". This would imply that the ball is "caught" for an appreciable amount of time and "thrown" downward. Note that the ball in on the stringbed for a mere 4-5 ms. Cannot "hurl" the ball downward with that type of contact time.

Note that the ball already has a downward motion before it is even contacted by the stringbed and is accelerating downward at 32 feet per second squared. Many, if nor most servers toss the ball somewhat higher than their contact ball and are, therefore, hitting a falling ball. Unless this fall is counteracted by the ball-string interaction, the ball continues to fall when it is struck.

I studied this Murray clip very carefully. If you stop the clip immediately prior to contact, the racket face is obviously open (pointing up). If you stop the vid shortly after the ball has left the strings, we observe that the racket face is now closed. However, if the video is stopped showing the ball on the stringbed, the racket is damn near vertical -- it is ever so slightly closed, if at all, as the ball leaves the strings. It is not appreciably closed until the ball has actually left the strings.

To my way of thinking, this video shows that he is actually hitting up on the ball, for the most part, since the racket head is "hurled" upward to meet the ball. The racket face, in this video, only starts to close as the ball leaves the strings. The ball is not "hurled downwards".


"The research also shows that as important, or more important than the total amount of spin is the type of spin. Of particular importance is the topspin component. First, it’s important to realize that a pure topspin serve is a myth. The research conclusively demonstrates that the majority of the spin on all serves is sidespin."

http://www.tennis.com/yourgame/instructionarticles/visuals/visuals.aspx?id=109012


So don't go around saying Sampras' "topspin" was 3000 to 5000 rpm. Most of it is sidespin, which is a sideswipe on the ball.

A sideswipe is not a "glancing blow"?

Kudos for providing this link. I had glanced at this article quite some time ago, but never got back to it to pick up on all the details. I would have thought that the topspin-to-sidespin ratio woould be somewhat closer to 50-50, perhaps something like 40-60.

However it turns out that the topspin component is about 35% according to this article. With an average first serve spin of 2700 rpm for Sampras, we are still talking about a heck of a lot of topspin. With a spin rate a bit under 1000 rpm, we are talking about 16 revolutions each second (topspin component) -- this is still an appreciable amount of Magnus Effect due to topspin.
.

[gzhpcu]

Don't forget the deformation of the ball and strings:

http://img22.imageshack.us/img22/5209/serveimpact1.jpg

http://img22.imageshack.us/img22/4550/serveimpact2.jpg

source: Plagenhoef's Fundamentals of tennis. Old book, example is of a wooden racquet, but principles still valid

[sureshs]

Was this written by any recognized authorities on serving? Just a we have unqualified people passing themselves off as experts on Expert Village, probably any fool can post a "how-to" on the site above. Regardless of whether we really hit up on the serve, or hit (slightly) down on the serve, it is "bad" coaching, for most students, to tell them to "try & hit down on the ball". However, it might be a suitable instruction for a few students -- those who consistently hit long or those who hit nothing but "powder puff" serves.




I believe that we've established that there are no "flat" serves. All serves have spin and all serves, to some extent, are "glancing blows".




There is a considerable amount of spin on this Murray serve, hence a glancing blow. A Sampras first serve averaged ~2700 rpm with some exceeding 4000 rpm according to one study (http://wings.avkids.com/Tennis/Project/usspin-07.html). In the same study, even the flattest of servers (Chang & Henman) employed ~1600 rpm on first serves. to my mind, these would all be glancing blows.

No, the served is not "hurled downwards". This would imply that the ball is "caught" for an appreciable amount of time and "thrown" downward. Note that the ball in on the stringbed for a mere 4-5 ms. Cannot "hurl" the ball downward with that type of contact time.

Note that the ball already has a downward motion before it is even contacted by the stringbed and is accelerating downward at 32 feet per second squared. Many, if nor most servers toss the ball somewhat higher than their contact ball and are, therefore, hitting a falling ball. Unless this fall is counteracted by the ball-string interaction, the ball continues to fall when it is struck.

I studied this Murray clip very carefully. If you stop the clip immediately prior to contact, the racket face is obviously open (pointing up). If you stop the vid shortly after the ball has left the strings, we observe that the racket face is now closed. However, if the video is stopped showing the ball on the stringbed, the racket is damn near vertical -- it is ever so slightly closed, if at all, as the ball leaves the strings. It is not appreciably closed until the ball has actually left the strings.

To my way of thinking, this video shows that he is actually hitting up on the ball, for the most part, since the racket head is "hurled" upward to meet the ball. The racket face, in this video, only starts to close as the ball leaves the strings. The ball is not "hurled downwards".




A sideswipe is not a "glancing blow"?

Kudos for providing this link. I had glanced at this article quite some time ago, but never got back to it to pick up on all the details. I would have thought that the topspin-to-sidespin ratio woould be somewhat closer to 50-50, perhaps something like 40-60.

However it turns out that the topspin component is about 35% according to this article. With an average first serve spin of 2700 rpm for Sampras, we are still talking about a heck of a lot of topspin. With a spin rate a bit under 1000 rpm, we are talking about 16 revolutions each second (topspin component) -- this is still an appreciable amount of Magnus Effect due to topspin.
.

Thank you very much. It is gelling into a background theory that I have been toying with - the ball is caught on the way up or at vertical and dispatched on the way down (in some cases) - the dwell time issue. Other times it is unambigously hit down. Other times up.

I also observed that the racquet was very nearly vertical at impact and not point up as if hitting up on the ball.

I agree that the racquet head is hurled up to meet the ball. However, as you point out, the face is closed as it leaves the strings. To me, that means that the ball is hit down. What finally happens to the ball is what counts. If I keep a ball in my palm facing downwards for 20 minutes, and then turn my palm upwards and throw the ball up, the ball is not going to go "hey i was looking down for 20 minutes, so I better remember that and fall down now."

Hurled down was a bad choice of words by me, but I was trying to capture the effect of dwell time and ball pocketing by using the phrase. Unfortunately, not everyone is capable of critical thinking here like you, so I have to use metaphors.

I see that you actually went thru the video instead of hurling insults at me (unlike some of the posters here). I guess I should be grateful for that.

Another interesting side issue that has come out is exposing the myth that the ball cannot be hit down and satisfy the geometry. All said and done, the ball is leaving downwards and still clears the net and lands in. As I analyzed before, it is because of the parabolic trajectory, which is completely missed in previous analyses - hence the "you gotta be 9 feet tall or whatever" argument.

Sideswipe is a glancing blow. If you got the impression that I disagreed, sorry. People have been quoting bits and pieces of what I post across multiple threads and misrepresenting me (a favorite one is that I said pros always hit down on the ball).

Back to the point, I agree that the motion is for the most part up. I think everyone can see that. But the ball doesn't know that.

I disagree with the gravity comment. If the ball is leaving the strings downward and the face is closed, it does not appear to me to be a significant issue of a resultant force. That somehow the ball is hit up and gravity pulls it down, and the resultant is slightly down. I thought much about it already. Even a club player can hit up on a second serve and the ball leaves upwards. It is difficult to believe that a ball hit upwards at pro speeds does not significantly overwhelm gravity.

I agree that hitting up on the ball is good coaching advice. But I am not a coach, nor a student. I am just studying what happens.

[sureshs]

Don't forget the deformation of the ball and strings:

http://img22.imageshack.us/img22/5209/serveimpact1.jpg

http://img22.imageshack.us/img22/4550/serveimpact2.jpg

source: Plagenhoef's Fundamentals of tennis. Old book, example is of a wooden racquet, but principles still valid

See my previous post on my thoughts about dwell time. Even if the ball is caught on the way up (in those cases that it is), it is dispatched on the way down.

e and f show the ball being hit down at the end of the dwell time. Thanks for the research.

And oh, there is not much of a "glancing blow" or "parallax error" in this pic LOL. The myth that a glancing blow is what causes the ball to move down while the frame is moving up has been exposed as a myth.

What happens to the ball at the end is what counts to the external world. It is being hit down.

[nousername]

See my previous post on my thoughts about dwell time. Even if the ball is caught on the way up (in those cases that it is), it is dispatched on the way down.

e and f show the ball being hit down at the end of the dwell time. Thanks for the research.

And oh, there is not much of a "glancing blow" or "parallax error" in this pic LOL. The myth that a glancing blow is what causes the ball to move down while the frame is moving up has been exposed as a myth.

What happens to the ball at the end is what counts to the external world. It is being hit down.
sureshs,

these are conceptual drawing they prove nothing about "glancing blows" and "parallax error". it is comments like these that bring your credibility into question.

FYI, regarding "glancing blows" ... do you know what a normal vector is? if so, imagine there the normal vector of the face of the racket. NOW imagine the velocity vector of the racket during contact. IF those 2 vectors are not parallel, it is a glancing blow.

restated in other words, when the normal vector and velocity vector are not parallel, there will always be a velocity component in the plane of the racket face. it is that component that causes spin and it is that component that defines "glancing blows".

SIDE NOTE: what is the probability that the normal vector and velocity vector are parallel??? ... a big FAT zero! thus all serves are glancing blows.

[nousername]

I disagree with the gravity comment. If the ball is leaving the strings downward and the face is closed, it does not appear to me to be a significant issue of a resultant force. That somehow the ball is hit up and gravity pulls it down, and the resultant is slightly down. I thought much about it already. Even a club player can hit up on a second serve and the ball leaves upwards. It is difficult to believe that a ball hit upwards at pro speeds does not significantly overwhelm gravity.

I agree that hitting up on the ball is good coaching advice. But I am not a coach, nor a student. I am just studying what happens.
hey sureshs,

i think the bold part absolutely correct, and i think everyone agrees.

but i also think it indicates you have misunderstood what we all mean by "hitting up".

at least for me (i cannot necessarily speak for other "hitting up" advocates), hitting up has never meant the ball has upward motion after contact. never, never, never. if it sounded like i ever said that, it was only the result of my poor writing and communication abilities.

in fact, the opposite is true. "hitting up" is a method to bring the ball down.

the whole reason i make a big deal out of it is b/c it is counter intuitive. the goal of "hitting up" is NOT to "make the ball go up". the goal is "swing UP in such a fashion that topspin is generated from contact, which brings the ball down".

[sureshs]

the whole reason i make a big deal out of it is b/c it is counter intuitive. the goal of "hitting up" is NOT to "make the ball go up". the goal is "swing UP in such a fashion that topspin is generated from contact, which brings the ball down".

I totally agree and also that the ball is actually made to go up in many cases.

However the topspin generated by contact is unlikely to bring the ball down immediately. That is why topspin shots or kick serves have a low-high-low path. The ball eventually comes down. But topspin produced by brushing up against the ball cannot be bringing down the ball instantaneously after contact, as we see in the videos. If that was the case, it means the upwards force could not even overcome gravity - the ball was brushed up with less force than what anyone can do - hit a falling ball from below and make it go up again. I know you will say that most of the force is forwards and not upwards, but if you watch the sudden racquet head acceleration in the videos before the ball is struck, it looks like a substantial hit and even a partial upward component will send the ball up on contact for a brief time

[stormholloway]

at least for me (i cannot necessarily speak for other "hitting up" advocates), hitting up has never meant the ball has upward motion after contact. never, never, never. if it sounded like i ever said that, it was only the result of my poor writing and communication abilities.

in fact, the opposite is true. "hitting up" is a method to bring the ball down.

the whole reason i make a big deal out of it is b/c it is counter intuitive. the goal of "hitting up" is NOT to "make the ball go up". the goal is "swing UP in such a fashion that topspin is generated from contact, which brings the ball down".

Exactly. That's why I kept asking how one defines "hitting up". I don't think I ever got an answer. You swing up. This is beyond any doubt. That's why I've been saying this has been an issue of semantics, which happens so often in tennis. I also think this is where the issue of the "wrist snap" comes from.

[larry10s]

what do you guys think about this. most pictures at contact of the serve the racquet is pretty vertical so that the main direction at contact is FOWARD on the ball with some up to impart spin. you are hitting up to get to the ball. i guess we can agree on this. the minor angle differences of of the racquet face minimally up (open face at contact) or minimally down (slightly closed face at contact) can vary from serve to serve and server to server.

[sureshs]

what do you guys think about this. most pictures at contact of the serve the racquet is pretty vertical so that the main direction at contact is FOWARD on the ball with some up to impart spin. you are hitting up to get to the ball. i guess we can agree on this. the minor angle differences of of the racquet face minimally up (open face at contact) or minimally down (slightly closed face at contact) can vary from serve to serve and server to server.

You are hitting up not only to get to the ball, but for two other reasons:

1. More height helps in easier clearance over the net and placement in the service box.

2. More height = more speed on the serve. The farther the point is from the axis in a rotational motion, faster it is moving.

That is why coaches ask students to hit up on the ball. The first instinct of a novice is to hit down on the ball. Actually that is the second instinct. First one is to hit up but in a powder puff manner.

Also, the two cases you mention (open and closed) seem to happening together in some cases. The ball arrives on an open face (in these cases) but leaves downwards from a closed face.

[J011yroger]

I wish I was the same way:( I need help with my volleys but I haven't posted a vid yet. I have to get on that ASAP. Just kinda hard with all the snow we're getting

And I'm looking foward to those vids, I'll see if I can learn a thing or two. I saw that vid of yours where you hit that kick serve over the back curtain, that was riddiculous! Especially if you use that serve when S&Ving, that's scary:shock:

I'll keep all this in mind when I shoot my vid. I'll try and get more than 1 view for sure.

But I think that's what makes you a really good player Jolly. You have a big ground game but can also S&V profciently. You can attack the net when you need too and can finish points from at net and at the baseline. I'm just a one dimensional S&Ver with below average volleys. I have a decent kick serve that I can place well, which is what is really going for me right now. And lol swinging at your serves wouldn't work unless the guy your playing has amazing timing, which isn't going to happen probably.

Thanks so much for the vid tips though, and good luck with your game and everything:)

Worked on my "Serve and Get Passed" game tonite.

Ran out of memory card, so I don't know how much I got.

Will go through now, and hopefully I got a few good points.

J

[Ballinbob]

Worked on my "Serve and Get Passed" game tonite.

Ran out of memory card, so I don't know how much I got.

Will go through now, and hopefully I got a few good points.

J

Looking forward to seeing it, should be pretty good. Not sure how you can get passed that easy w/ your serve though lol. You'll have to prove me wrong here:)

[J011yroger]

Looking forward to seeing it, should be pretty good. Not sure how you can get passed that easy w/ your serve though lol. You'll have to prove me wrong here:)

My buddy passed me cleanly off a few returns. And I botched a few 2nd volleys. One return I hit a bomb of a serve, and he slapped it straight back down the line by a lunging Jolly. I cut loose a "Mother F'er" and this guy was on the court next to us and his 14 year old daughter both turned and looked at me, and I was like "Did I say that out loud?"

J

[Ballinbob]

My buddy passed me cleanly off a few returns. And I botched a few 2nd volleys. One return I hit a bomb of a serve, and he slapped it straight back down the line by a lunging Jolly. I cut loose a "Mother F'er" and this guy was on the court next to us and his 14 year old daughter both turned and looked at me, and I was like "Did I say that out loud?"

J

That's pretty funny haha! I cuss all the time too while playing, it's just a natural instinct now. Plus sometimes it intimidates the opponent so more power to me lol. But yeah that's the thing with S&Ving, your opponent knows your coming in so they start to get smart with their returns. But I guess that's when you crank up your serve:)

Do you usually S&V with a kick serve or flat serve though? Also, where do you usually make your first volley from?

[J011yroger]

That's pretty funny haha! I cuss all the time too while playing, it's just a natural instinct now. Plus sometimes it intimidates the opponent so more power to me lol. But yeah that's the thing with S&Ving, your opponent knows your coming in so they start to get smart with their returns. But I guess that's when you crank up your serve:)

Do you usually S&V with a kick serve or flat serve though? Also, where do you usually make your first volley from?


You will see, am compiling the vid now.

I try to close too tightly and rush the 1st volley. My coach is trying to make me slow down, and have a more defined split.

You will have to trust me when I tell you I suck at it, and it is 110% a work in progress.

Oh, and there was no cranking up the serve tonite lol. My back wouldn't let me even if I wanted to.

J

[maverick66]

you trying to slow your speed towards the net? dont you want to close the gap as fast as possible? i understand not running straight forward into the net and rushing the volley but i think we are having a communication issue on that one.

[J011yroger]

you trying to slow your speed towards the net? dont you want to close the gap as fast as possible? i understand not running straight forward into the net and rushing the volley but i think we are having a communication issue on that one.

No, he wants me to be more collected and balanced, and have a rhythm. Better to be further back, prepared and collected, than to be closer and off balance/rushing.

I would be blitzing forward to try to hit a volley, and end up having to hit a low volley while moving forward, instead of spliting, hitting it as a half volley and then continuing forward.

J

[J011yroger]

Looking forward to seeing it, should be pretty good. Not sure how you can get passed that easy w/ your serve though lol. You'll have to prove me wrong here:)

Here it is, don't laugh.

Well you can laugh if you want to. I laugh at myself all the time, especially when I watch myself feebly attempting to S&V.

http://vimeo.com/4009120

J

[maverick66]

i watched your video and your better when you stay back hit a ball then come forward. i see what you mean by no split step. you just run into the ball but your aware.

[J011yroger]

i watched your video and your better when you stay back hit a ball then come forward. i see what you mean by no split step. you just run into the ball but your aware.

Yea, I am much more comfortable coming in behind a big groundie, or slice approach, or even the sneak attack ploy out of the middle of nowhere than right behind the serve.

I played my first singles match pure S&V in December, so, it is still in the very early stages.

We practice 1/3 speed so that I can get the timing and movement down.

I will get it eventually, I am too stubborn not to.

J

[J011yroger]

Some days I just have it, and it comes more naturally and I give the appearance of being competant. Today wasn't one of those days, but I wanted to get it on film, so I kept after it.

If I had to play for money, I would certainly have been staying back today.

In the grand scheme of things I only see myself S&V 1/3 or 1/4 of the points just to keep the other guy honest. Or in Dubs. I don't think I will ever be good enough at it to rely on it any more than that. Tough enough for me as it is, take away the element of surprise, and it is just more trouble.

J

[maverick66]

its a sneak play for you. always nice to throw it in to keep the other guy guessing. i did the same. if i was playing and it was tight i would throw it in there to get the other guy off his game and think about it. i wouldnt go into a match thinking 1/4 im gonna s&v but more along the lines off if im up 30-15 and hes tight im gonna do it.

[J011yroger]

its a sneak play for you. always nice to throw it in to keep the other guy guessing. i did the same. if i was playing and it was tight i would throw it in there to get the other guy off his game and think about it. i wouldnt go into a match thinking 1/4 im gonna s&v but more along the lines off if im up 30-15 and hes tight im gonna do it.

Exactly, and I am hoping that the threat of me coming in will take away their "Just block it back deep" mindset, and have them thinking that they have to put a swing on the return, which should net me some more free points on their returns.

And yea, I would never go into a match with a predetermined amount in mind, I would see how he is returning, and how it is working out for me. If I am winning the majority of points, I will keep at it, if I am losing them, I will stay back.

J

[Ballinbob]

Here it is, don't laugh.

Well you can laugh if you want to. I laugh at myself all the time, especially when I watch myself feebly attempting to S&V.

http://vimeo.com/4009120

J

Good long vid, I liked it. Thanks for posting it.

But I really think you should hit some more spin on your serves if your going to S&V. I noticed you were hitting alot of volleys from behind the service line, which is a hard shot no matter how good of a volleyer you are. Your just hitting bombs to the guy and your forced to rush the net quicker than you can, which is why you seem offbalance alot. If you hit a slower kick serve I'm pretty sure you'll get better results when S&Ving.

Your volley technique is pretty good, it's just the movement part. Once you get that down then your golden lol. But yeah I agree with maverick that your better at approaching behind a groundstroke then after a serve. I really like your slice though, stays low and looks deadly:shock:

My god though it never ceases to amaze me how much power you have in your game. You hit it so hard but you don't even look like your trying, its riddiculous lol

[J011yroger]

I promise I am not trying to hit hard, 60% effort max in that vid.

Glad I got some on vid, will be a good benchmark as I continue to improve at the S&V. So I can see what is changing and getting better, and what still sucks.

J

[maverick66]

My god though it never ceases to amaze me how much power you have in your game. You hit it so hard but you don't even look like your trying, its riddiculous lol

im guessing hes pretty relaxed through his strokes. at least on the forehand side. it allows him to accelarate his racket with ease. on the backhand side hes a little jerky but he rotates through the ball well. its not hard to with power. its hard to control that power.

[Jaewonnie]

I was wondering, I fast are your flat serves?

[J011yroger]

I was wondering, I fast are your flat serves?

Haven't hit many of them since the end of summer, and haven't been on a gun since the very beginning of last spring. April 2008 I think.

If we get a nice warm calm day I will go out and starch a few and try to put up the big number just for giggles.

J

[Djokovicfan4life]

Here it is, don't laugh.

Well you can laugh if you want to. I laugh at myself all the time, especially when I watch myself feebly attempting to S&V.

http://vimeo.com/4009120

J

I like those hard slice approaches at the start of this vid. That lunging forehand slice approach was epic at about 3:27, complete with the pirate's grunt.

[Ballinbob]

I promise I am not trying to hit hard, 60% effort max in that vid.

Glad I got some on vid, will be a good benchmark as I continue to improve at the S&V. So I can see what is changing and getting better, and what still sucks.

J

That's 60% of your max effort? I can't imagine how fast you serve during the summer/warmer weather.

Holly Bajeezus:shock:

[J011yroger]

Side view of me serving at contact.

Figure I would stir up the pot again.

I took some high speed after I was done fooling around, but it was too dark and it came out bad.

Plus I wasn't really feelin it so poor day to use to analyze my serve.

But here are 3 frames from around contact on the sideline. I suppose near the opposite service box wouldn't be too much further away, so we should be able to judge well.

http://i26.tinypic.com/14o52rc.jpg

http://i28.tinypic.com/2moq9n4.jpg

http://i26.tinypic.com/2rfd28p.jpg

J

J

[J011yroger]

3 frames from high speed shot at 210fps.

J

[drakulie]

^^hard to tell from the photos, but it appears in the second frame you have already made contact, and the ball is beginning to travel forward.

What is telling is that before contact, your racquet hasn't reached maximum height, which means it had to travel "up" to make contact with the ball,.

[Pet]

Here it is, don't laugh.

Well you can laugh if you want to. I laugh at myself all the time, especially when I watch myself feebly attempting to S&V.

http://vimeo.com/4009120

J

I can´t understand how a very bad player like you, have 20 k90. You are the type of player that I hate :twisted: