# Would swinging low to high with a slightly OPEN racket face at contract make slice?

## Would swinging low to high with a slightly OPEN racket face at contract make slice?

• ### The ball will have topspin on it

• Total voters
18

#### WildVolley

##### Legend
Yeah, that's what I mean, forward and up. When you go forward and up with a slightly open racquet face, the strings will strike the ball from below the equator of the ball and it can only hit it flat from below the equator of the ball.

To brush when striking below the equator of the ball, you have to pull back towards you a bit.

Just imagine the racket is open 3 degree from vertical and the ball only has a horizontal component as it moves into contact, but the racket is moving up at a 45 degree path (vector).

The ball will start compressing into the strings at 3 degrees below the equator but since the vector of the racket is at 45 degrees, as the ball compresses it will move down slightly against the string as it compresses and the racket pulls up against the outer wall of the ball. As it releases from the string bed it will have topspin.

#### Cowboyardee

##### Rookie
It's not very difficult to explain. Many of you are getting tripped up on the question of what 'open' means.

An open racquet face with respect to the ground (the racquet head is tilted back from perpendicular to the ground) doesn't tell you much of anything about what kind of spin you'll get. Not on its own. The ground (or horizontal) is actually a completely arbitrary reference point in this question.

The important factor is whether the racquet face is open with respect to the swing path at impact. An open face with respect to the swing path produces slice; a closed face with respect to the swing path produces topspin; a racquet face perfectly perpendicular to your swing path at impact produces no spin (this is nearly impossible to do in practice).

As such you can hit a shot with your racquet open with respect to the ground and get top spin if your swing path at impact is at an even steeper upward angle than your racquet face.

(ETA: the incoming angle of the ball does make some difference, but I believe its influence is thoroughly dwarfed in comparison to the racquet head's angle with respect to the swing path)

Last edited:

#### Enga

##### Hall of Fame
I think it would be like the shot Roger Federer hits on this video. https://m.youtube.com/watch?v=XRJTLGFKNP4

His swing path in that video is admittedly somewhat downwards. But anyway, if you open up the racket face too much, you'll get slice.

#### Cowboyardee

##### Rookie
It's not very difficult to explain. Many of you are getting tripped up on the question of what 'open' means.

An open racquet face with respect to the ground (the racquet head is tilted back from perpendicular to the ground) doesn't tell you much of anything about what kind of spin you'll get. Not on its own. The ground (or horizontal) is actually a completely arbitrary reference point in this question.

The important factor is whether the racquet face is open with respect to the swing path at impact. An open face with respect to the swing path produces slice; a closed face with respect to the swing path produces topspin; a racquet face perfectly perpendicular to your swing path at impact produces no spin (this is nearly impossible to do in practice).

As such you can hit a shot with your racquet open with respect to the ground and get top spin if your swing path at impact is at an even steeper upward angle than your racquet face.

(ETA: the incoming angle of the ball does make some difference, but I believe its influence is thoroughly dwarfed in comparison to the racquet head's angle with respect to the swing path)

In other words, Wildvolley is right, but most of you guys are hung up on horizontal and vertical reference points which are completely arbitrary in this this conversation. Open or closed with respect to horizontal doesn't matter because we're talking about spin, not trajectory.

#### WildVolley

##### Legend
In other words, Wildvolley is right, but most of you guys are hung up on horizontal and vertical reference points which are completely arbitrary in this this conversation. Open or closed with respect to horizontal doesn't matter because we're talking about spin, not trajectory.

You've explained this more concisely than I did.

I was very confused about whether people were talking past each other because of different definitions of the terms or whether someone was just confused, or whether someone was just trolling.

I also still stand by doing an empirical experiment for yourself. You can just drop a ball onto a tennis court and then swing into it with an upward racket path and a slightly open face and watch the topspin. I guess I took a little offense when some claimed I was either a liar saying I saw this or that I was subconsciously closing the racket face at contact.

#### Rui

##### Semi-Pro
I think Cowboyardee got it. If the swing path is steep enough, the ball will turn over, even with a slightly open face.

#### sureshs

##### Bionic Poster
As such you can hit a shot with your racquet open with respect to the ground and get top spin if your swing path at impact is at an even steeper upward angle than your racquet face.

No, you will still get slice unless the ball goes backwards in which case you can call it top spin towards the back fence if you wish!

#### Rui

##### Semi-Pro
Don't you think that dropping a tennis ball straight down on an open face, a la /, that the ball will come off with a topspin?

#### sureshs

##### Bionic Poster
Don't you think that dropping a tennis ball straight down on an open face, a la /, that the ball will come off with a topspin?

Yes.................

#### WildVolley

##### Legend
No, you will still get slice unless the ball goes backwards in which case you can call it top spin towards the back fence if you wish!

Sureshs, so you don't embarrass yourself further, please hit a tennis ball with an upward swinging racket path at a greater angle than the racket is open from vertical. Then report back what happens.

#### mntlblok

##### Hall of Fame
Changeover from topspin to underspin with racket tilt

Played with the inputs a bit and came sorta close to no spin (77 rpm's of topspin) with the following:
incoming spin of 1000 rpms of topspin
swing speed of 25mph
swing angle of 65 degrees upward
racket tilt of -20 degrees
https://www.flickr.com/photos/mentalblock/16223661184/

Interestingly, it's not a straight line change for the spin when you manipulate just one of the above parameters.
https://www.flickr.com/photos/mentalblock/16232549294/

Tried it again and added the inputs to the graphic. Also figgered out that you have to look below the graphic to learn whether the spin posted in the graphic is topspin or underspin. Might be straight-line after all. . .

#### Cowboyardee

##### Rookie
No, you will still get slice unless the ball goes backwards in whh case you can call it top spin towards the back fence if you wish!

You say this on what basis? I explained why you get topspin and can explain why again or another way if needed, but you didn't address the explanation. Also, this is a stupid-easy experiment to go perform yourself and shoot a big hole in your premise.

So what exactly don't you understand about the explanation I provided? You seem to be merely restating your conclusion even as the argument for it falls apart.

#### thomasferrett

##### Hall of Fame
Sureshs, so you don't embarrass yourself further, please hit a tennis ball with an upward swinging racket path at a greater angle than the racket is open from vertical. Then report back what happens.

We can all do this, but it's very hard to see with the naked eye what kind of spin is being put on the ball.

Also, if we concede that you ARE putting topspin on the ball even by contacting with an open racket head face, are you severely reducing that topspin by the face being slightly open?

So, say you swing at 100mph racket head speed and the face is 3 degrees closed, and you get 4000rpm topspin. If you take the same racket head speed and path, but hit with the face at 3 degrees open, how much would the topspin drop by? Would it drop to about 3800rpm? 3200rpm? 1000rpm? 50rpm?

You see what questions I'm getting at...

#### WildVolley

##### Legend
We can all do this, but it's very hard to see with the naked eye what kind of spin is being put on the ball.

It wasn't difficult for me to see. You can put a dot on the ball to help see the spin if you're having difficulty seeing it.

Also, if we concede that you ARE putting topspin on the ball even by contacting with an open racket head face, are you severely reducing that topspin by the face being slightly open?

Because of the higher launch angle from the open face, it is going to be easier to hit the ball long with an open racket face. So I believe that makes it more difficult to swing very fast and still have the ball drop in the court.

It is also more difficult to put spin the ball facing a fast incoming ball if the face is at all open. Sureshs seemed to disagree with this if I read him correctly. But honestly, his analysis still confuses me.

So, say you swing at 100mph racket head speed and the face is 3 degrees closed, and you get 4000rpm topspin. If you take the same racket head speed and path, but hit with the face at 3 degrees open, how much would the topspin drop by? Would it drop to about 3800rpm? 3200rpm? 1000rpm? 50rpm?

You see what questions I'm getting at...

Your best bet is to put this into the TW calculator. My guess is if the ball has incoming topspin (which most balls do) the closed racket is going to allow you to put more spin on the ball and the open racket won't allow you to hit as much spin.

#### Cowboyardee

##### Rookie
We can all do this, but it's very hard to see with the naked eye what kind of spin is being put on the ball.

Also, if we concede that you ARE putting topspin on the ball even by contacting with an open racket head face, are you severely reducing that topspin by the face being slightly open?

So, say you swing at 100mph racket head speed and the face is 3 degrees closed, and you get 4000rpm topspin. If you take the same racket head speed and path, but hit with the face at 3 degrees open, how much would the topspin drop by? Would it drop to about 3800rpm? 3200rpm? 1000rpm? 50rpm?

You see what questions I'm getting at...

If the dot trick doesn't work, perhaps hitting a wet ball would make this easier for you to see with your naked eye, as water flies off the ball?

In truth determining the exact rate of spin is a fairly difficult physics problem, involving many factors. Determining the direction of spin, on the other hand, is quite easy. It helps to simplify the scenario in your head: Don't imagine a person standing on the ground, swinging a racquet at a moving ball with a tennis swing. Just imagine a racquet in empty space swinging toward the ball.

If it hits the ball with the racquet face perpendicular to the swing plane, it drives it straight without spin (or at least with comparatively little spin, since hitting no spin is nearly impossible). Easy to visualize, right? Open the racquet face with respect to the swing plane and you'll get slice. Close it with respect to the swing plane and you get topspin.

Exactly how much? That depends on many factors (and yes, it's even possible that those other factors could result in counter-intuitive spin direction given a highly marginal situation - say, a racquet only 0.1 degree open with respect to the swing plane). But 99%+ of the time, spin direction is determined by the simple scenario spelled out above.

#### toly

##### Hall of Fame
We can all do this, but it's very hard to see with the naked eye what kind of spin is being put on the ball.

Also, if we concede that you ARE putting topspin on the ball even by contacting with an open racket head face, are you severely reducing that topspin by the face being slightly open?

So, say you swing at 100mph racket head speed and the face is 3 degrees closed, and you get 4000rpm topspin. If you take the same racket head speed and path, but hit with the face at 3 degrees open, how much would the topspin drop by? Would it drop to about 3800rpm? 3200rpm? 1000rpm? 50rpm?

You see what questions I'm getting at...

If a ball has zero speed then its spin (S) in rpm can be calculated according to next formula

S = 1.45* V*A

Where V is the racquet head speed in mph and A is the angle between directions of the racquet velocity and perpendicular to the racquet’s strings in degrees.

In your post: V = 100mph and S = 4000rpm, therefore the angle A is

A = S/(1.45*V) = 4000/(1.45*100) = 28°

In case of racquet face at 3° open the A angle will be A = 22° and ball’s spin

S = 1.45*100*22 = 3190rpm

#### mntlblok

##### Hall of Fame
We can all do this, but it's very hard to see with the naked eye what kind of spin is being put on the ball.

Also, if we concede that you ARE putting topspin on the ball even by contacting with an open racket head face, are you severely reducing that topspin by the face being slightly open?

So, say you swing at 100mph racket head speed and the face is 3 degrees closed, and you get 4000rpm topspin. If you take the same racket head speed and path, but hit with the face at 3 degrees open, how much would the topspin drop by? Would it drop to about 3800rpm? 3200rpm? 1000rpm? 50rpm?

You see what questions I'm getting at...
Was gonna plug those into the "shot maker" tool, but you need to at least add the swing angle. Let's say it's 30 degrees upward. Oops. Need to go with the face tilted forward (closed) at least 7 degrees closed to keep it in the court - assuming that the incoming ball has 4000 RPM's of topspin on it - the way the tool is initially set up. So, let's play with a common complaint here, too, and have the ball be a slow floater without much spin. Things get a lot more interesting. Let's say 1000 RPM's of top and 20 MPH of incoming speed, and go back to the 3 degrees closed racket face. That gets us to a little over 3000 RPM's of topspin.

Now, we just change that 3 degrees closed face to a 3 degrees open face. The spin drops to 2383 RPM's of topspin, but the change in launch angle causes the ball to land over 30 feet long.
https://www.flickr.com/photos/mentalblock/16674188450/ The red ball shows the closed face result.
https://www.flickr.com/photos/mentalblock/16860547391/ The red ball shows the open face result.

Yer welcome. :mrgreen:

#### sureshs

##### Bionic Poster
My guess is if the ball has incoming topspin (which most balls do) the closed racket is going to allow you to put more spin on the ball and the open racket won't allow you to hit as much spin.

Which pro hits a deliberate topspin shot with an open face and just relies on incoming spin and friction? When he wants to hit topspin, he face is closed or neutral. When he hits a defensive lob by punting the ball back up high with an open face, he will never claim to "put topspin" on the ball or "hit with topspin."

Last edited:

#### mntlblok

##### Hall of Fame
Which pro hits a deliberate topspin shot with an open face and just relies on incoming spin and friction? When he wants to hit topspin, he face is closed or neutral. When he hits a defensive lob by punting the ball back up high with an open face, he will never claim to "put topspin" on the ball or "hit with topspin."
https://www.flickr.com/photos/mentalblock/16789281796/in/set-72157650697596641 You ask for evidence, but then seem to choose to ignore it. . .

#### Narcissist

##### Semi-Pro
Topspin but yes, the angle matters:

#### mntlblok

##### Hall of Fame
Blog page

I'm betting that yer not the author of that blog page. It's interesting stuff, but I don't think it's related to the topic at hand. The "tilts" here are related to what happens to the racket face *after* contact. If the contact is made below the center of the strings, then it causes the racket to tilt forward after contact (twist in the player's hand). And, if the contact is made above the center, up near the top of the frame, then it twists the frame into an open position (tilted backwards). He also notes that the racket remains "stable", or doesn't twist, if the ball is contacted near the center of the string-bed.

The fascinating part of the article, though, is that he sez he's measured the spin from these three types of contacts and has found that the contact near the bottom edge of the frame generates more topspin. I might have guessed the opposite. Now I wonder if these top guys might be doing some of this on purpose. . . Hmmm. . .

#### ttbrowne

##### Hall of Fame
I notice that the racquet face is not open at contact but straight up and down. After the ball comes off...the racquet tilts backward.

#### mntlblok

##### Hall of Fame
I notice that the racquet face is not open at contact but straight up and down. After the ball comes off...the racquet tilts backward.
Right. The article explains about that. Different issue.

Interestingly, Dolgopolov, at 7-6, 4-2 against Raonic, hits a topspin lob, and the replay clearly shows his open racket face for the steeply upward stroke.

#### sureshs

##### Bionic Poster
https://www.flickr.com/photos/mentalblock/16789281796/in/set-72157650697596641 You ask for evidence, but then seem to choose to ignore it. . .

And however many times I tell you that the incoming spin was 4000 rpm, you choose to ignore it.

Do you know that there is something called a rebound coefficient which is used for non-spin studies? Shoot a ball at a stationary racket at 70 mph, and it will come back with a speed of x*70, x < 1. The simplest model for a groundie speed is: racket head speed + x*incoming ball speed.

Will you claim that the second term is consciously created by the player by simply holding a frame in his hands?

#### sureshs

##### Bionic Poster
https://www.flickr.com/photos/mentalblock/16232549294/

Tried it again and added the inputs to the graphic. Also figgered out that you have to look below the graphic to learn whether the spin posted in the graphic is topspin or underspin. Might be straight-line after all. . .

As your graphic suggests, play with a -23 degrees tilt open face and you will get a whopping 6 rpm of topspin. It is topspin after all, right?

#### Povl Carstensen

##### Legend
I think we went over this in another thread. I was contradicted many times but no one could disprove me at the end.
It is very easy to take a ball (and a racket) and hit a topspin shot with a slightly open face, and prove it to yourself. As I did and others confirmed. I will not post a video.

#### Povl Carstensen

##### Legend
You're likely pulling back during that swing without even knowing it. With open face racquet swing FORWARD low to high, can't really get topspin since strings can't brush up on the back of the ball UNLESS you are pulling back (even subtly) not going forward.
Ofcourse you can brush upward with an open racket even if the racket is moving foreward. As long as the movement of the racket is more upward than the 90 degrees vektor of the string plane. In that case you are hitting low to high on the ball. If the direction of the racket is lower than the 90 degrees vektor, you are slicing. If they coincide, you are hitting straight forward with no spin.
Of course the up/downwards movement of the ball, and the spin on the incomming ball are also factors, but that does not change the above.

Last edited:

#### Povl Carstensen

##### Legend
You guys carry on since you don't want to accept defeat or learn anything new.
This is actually funny.

#### Cowboyardee

##### Rookie
As your graphic suggests, play with a -23 degrees tilt open face and you will get a whopping 6 rpm of topspin. It is topspin after all, right?

A genuinely realistic model for determining spin would include variables for the ball's spin before impact, the ball's weight, the ball's incoming angle, rotational angle of the racquet face at impact, the racquet's weight and acceleration, string tension and coeficient of friction (both with itself and the surface of the ball), and a dozen other variables. We're really talking NASA level calculations to arrive at an answer that begins to get precise. The graphics posted in this thread are good illustrations but (necessarily) simplified.

I guess I just don't even know what you're arguing anymore...

- That it's impossible to hit topspin with your racquet face open with respect to the ground? Hopefully you recognize that's not a tenable position at this point.

- That no decent/pro tennis player ever actually hits a topspin shot with the racquet face open (again, with respect to the ground/horizontal)? I believe many do on feeds and on topspin/offensive lobs, but perhaps high speed video would clear this issue up.

- Or whether those topspin lobs have high or low rates of topspin? Simple calculations and equations are pretty inadequate to answering this question in a satisfactory manner. Again, high speed video might be the most useful way to answer this question, but my offhand experience is that some of these shots have rates of spin significantly higher than 6 rpm and are often hit with the racquet face somewhat open.

#### WildVolley

##### Legend
A low to high swing in which the racket is moving forward with an open face CANNOT produce topspin "by itself," meaning that it does produce a tiny amount of topspin due to the recoil of the strings (which is also produced by a stationary racket).

The majority of people on this thread argue that the above is wrong if we change it to slightly open.

Do you still maintain that spin is due to "string recoil" rather than standard topspin generation by a racket when we're talking about hitting a ball with a slightly open racket face and a forward racket vector at greater upward angle than the strings are open?

Have you tried it on court yet?

#### mntlblok

##### Hall of Fame
See the TWU experiment "How Impact Location and Twistweight Affect Spin".

http://twu.tennis-warehouse.com/learning_center/location.php

So, the study the guy did was accurate, then, right? Any idea if pros are aware of this and utilize it?

Pretty cool to actually hear from the professor. I assume he is Crawford Lindsey? I am _Technical Tennis_'s biggest fan. :mrgreen: One of the posters might take a look at the first paragraph on page 122 of same.

I would also note that my attempts to duplicate the results from what is predicted by the Shot Maker tool suggest that they are *very* accurate and model the real world right well. I've found some wonderful insights from experimenting with the tool. If you ever need a guinea pig. . .

Kevin Bryant
Savannah, GA

Replies
58
Views
11K
Replies
11
Views
1K
Replies
10
Views
753
Replies
6
Views
2K
Replies
24
Views
3K