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After a week of trying to straighten out what the Magnus coefficient should be for a TT ball it seems that no one really knows exactly. So I picked one that matched the trajectories I see in videos. Especially a Butterfly chopper video and the Sakai fastest serve ever video. I have made a pdf with about 10 different combinations of top and bottom spins with varying initial conditions which include the distance from the net at impact, the height above or below the table top, the initial spin, speed and angle.
What is clear is that if the ball is hit while close to the table but from below the net, a fast paddle will not be your friend. The initial speeds are in the range of about 15 m/s. This varies depending on the initial angle and spin. 15 m/s not that fast. Some of the simulations use speeds of 20 m/s and 75 rps. This might be on the high end of what is achievable. It isn't hard to flat hit a ball much faster but to brush the ball enough to get 75 rps and also a speed of 20 m/s takes a much faster swing. When back from the table, a faster paddle is better to compensate for the air resistance. Reducing spin keeps the ball from dropping too soon.
The reason this interests me is that the tables are "too short". Actually I hit the ball just a little too fast with not enough spin to bring the ball down fast enough. I can see the arc of the ball but it often just misses the end of the table. Lowering the initial angle is not good either since the net snags too many of my returns. Another item is keeping the ball low. Keeping the ball low so its peak height is less than 200 mm is the goal 250 mm is OK and probably safer. A ball that has a peak height of 200 mm will bounce up at about 80% of that height. A little more with back spin and less with top spin. Keeping the ball low forces the other guy to loop the ball over the net instead of just drive it from above the net.
One thing you should notice is that a change of the initial angle of just one degree makes a big difference on how deep the ball lands if it lands at all.
https://deltamotion.com/peter/TableTennis/Mathcad - TT Spin Speed Angle Trajectory.pdf
BTW, I just saw a Rozena add on Amazon where it claimed to correct for errors in the paddle. How does it do that? It can't.
What is clear is that if the ball is hit while close to the table but from below the net, a fast paddle will not be your friend. The initial speeds are in the range of about 15 m/s. This varies depending on the initial angle and spin. 15 m/s not that fast. Some of the simulations use speeds of 20 m/s and 75 rps. This might be on the high end of what is achievable. It isn't hard to flat hit a ball much faster but to brush the ball enough to get 75 rps and also a speed of 20 m/s takes a much faster swing. When back from the table, a faster paddle is better to compensate for the air resistance. Reducing spin keeps the ball from dropping too soon.
The reason this interests me is that the tables are "too short". Actually I hit the ball just a little too fast with not enough spin to bring the ball down fast enough. I can see the arc of the ball but it often just misses the end of the table. Lowering the initial angle is not good either since the net snags too many of my returns. Another item is keeping the ball low. Keeping the ball low so its peak height is less than 200 mm is the goal 250 mm is OK and probably safer. A ball that has a peak height of 200 mm will bounce up at about 80% of that height. A little more with back spin and less with top spin. Keeping the ball low forces the other guy to loop the ball over the net instead of just drive it from above the net.
One thing you should notice is that a change of the initial angle of just one degree makes a big difference on how deep the ball lands if it lands at all.
https://deltamotion.com/peter/TableTennis/Mathcad - TT Spin Speed Angle Trajectory.pdf
BTW, I just saw a Rozena add on Amazon where it claimed to correct for errors in the paddle. How does it do that? It can't.