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View Full Version : Angle vs Direction of Racquet Face

riposte_18
12-04-2012, 08:51 PM
Hey all,

Been getting into golf a little, and one of the interesting things that has been bandied about their forums is that its the angle of the racquet face at impact that determines the flight of the ball, the direction the racquet is moving impacts the spin applied.

I was thinking about this in terms of tennis strokes, and wondered if this held 100% true as well? Does the direction the racquet is moving impact the direction the ball comes off the racquet? Or is it only the angle? Is golf too different to tennis, due to the friction and grip of a tennis racquet to a golf club head?

Take, for example, a racquet face 90 degrees perpendicular to the ground. I'm waving it vertically, but not giving any horizontal motion (ie, a giant handshake). If a ball came flying parallel to the group at the racquet on my upswing, obviously a topspin will be applied to the ball, but will the ball come back off parallel to the group, or with an upwards trajectory?

Is this just nonsense? I've seen tons of pics with pros hitting forehands where their racquets are angled slightly downwards, and even my own hitting experience tells me that the direction of the racquet must have *some* input into which direction the ball comes off the racquet, but ... would appreciate some knowledgable input?

Bagumbawalla
12-04-2012, 09:24 PM
Rather than ask what other people think of your idea, why mot just go outside and do exactly what you just described- then let us know the result?

riposte_18
12-04-2012, 09:42 PM
I have tried on occasion, but there's a couple of variables that reduce my ability to test it out. Its hard enough during a normal swing to be sure of what angle I'm holding the racquet, since a few degrees can cause the rebound to behave differently, and because the whole motion feels so unusual (ie, keep a racquet perpendicular to the ground while moving in a upwards motion while aiming to hit the ball and looking at the response of the ball from the racquet), its hard to properly analyse. Plus, things like gravity come into effect so its hard to investigate. Did the ball come of the racquet like that because it was already travelling upwards? Was my racquet really straight while I was focusing on the incoming ball? etc, etc

I guess I'm looking for more a grounded answer or even consensus by experienced majority?

SystemicAnomaly
12-04-2012, 10:01 PM
What group are you referring to in your post? Should I assume that you meant ground?

The angle (and speed?) of the incoming ball, the angle of the racquet face, and the swingpath of the racquet will have a bearing on the spin type, spin amount and the exit angle when the ball leaves your strings.

One difference in golf is that there is no incoming angle of the ball since it is stationary, on the ground, before it is struck. I believe that there are a limited number of swing paths in golf. Putts will, effectively, have topspin while all other shots in golf have underspin (I think).

If you really want to investigate some of the ideas that you have brought up in your OP, then get your hands on a copy of Technical Tennis by Rod Cross and Crawford Lindsey...

http://www.racquettech.com/images/store/technical_cover.jpg

Bagumbawalla
12-04-2012, 10:13 PM
Try laying the racket flat (or clamp it to something that rotates) and drop the ball from a fixed height- the gravitional effect will be minimized. Actually, you don't even need to use a racket- get a belt sander and level it up and drop a ball straight down... if it has variable speeds...

Draw a chalk line perpendicular to the sidewalk, and as a bus drives by, throw a tennis ball straight at its flat side, measure the angle of deflection.

These could be high school science projects.

LeeD
12-05-2012, 10:05 AM
It's not a science project, it's a LOGIC project.
Of course, every different angle introduced changes the angle of the ball leaving the hitting surface.

dominikk1985
12-05-2012, 12:32 PM
It also depends on whether you hit the ball rising or falling.

In table tennis you learn to hit a topspin with a closed face if you hit it early and with a vertical face when the ball is falling.

this is because the rising ball needs to be "pushed down" since the natural deflection of the ball from the racket is up. the falling ball on the other hand needs to be "lifted". it probably applies less to tennis then to table tennis.

SystemicAnomaly
12-06-2012, 03:57 AM
^ No, it applies just as much to tennis as it does with to table tennis. You will see players hitting with a closed face on high rising balls and more of a vertical racket face on falling balls. With table tennis, the closed face is often more evident. With tennis it is often a bit more subtle -- we sometimes cannot tell if the racket face is actually closed at contact unless we observe it on hi-def slow motion videos.

mntlblok
12-10-2012, 08:37 AM
If you *really* want to have fun with this stuff, don't miss the hours of fun you can have at http://twu.tennis-warehouse.com/cgi-bin/trajectory_maker.cgi It meshes nicely with "Technical Tennis" and might have even been put together by the same guys. Anyway, the swing path and the racket face angle *do* both have an effect on the trajectory.

Whilst one would think that all this stuff is strictly logic, there are some mighty counterintuitive aspects of a lot of this stuff - at least counterintuitive to *me*. Some of the tests with high speed video that Cross and Lindsey have run are just mind boggling.

I believe a putt actually "skids" for a few inches before attaining its topspin.

I wish SystemicAnomaly lived closer to my part of the world. I'd love to sit down and pick his brain sometime. It's just so rare to have anyone to talk to about this stuff whose eyes don't immediately glaze over and suddenly remember that there's somewhere else they needed to be. :mrgreen: