How different spins and velocities affect the flight of a tennis ball.

1. How spin affects the flight
of a tennis ball
Stephen Hills

2. Why spin is important to the flight of the ball
Top Spin - provides a downward
force to the ball, which makes it
drop faster, allowing for the ball
to be hit faster.
Backspin - provides an upward
force to the ball, making the ball
stay in the air longer.

3. Side Spin
https://youtu.be/v7gQ-vySQMk?t=46

4. Star CCM+ Model
Top Spin ( 4000 rpm at 35 m/s)
Calculated values
Cl = 0.171
Cd = 0.298
Values from study
Cl = 0.12
Cd = 0.5

5. Star CCM+ Model
Backspin (4500 rpm at 35 m/s)
Calculated values
Cl = 0.173
Cd = 0.341

6. Star CCM+ Model
Side Spin (1000 rpm at 35 m/s)
Calculated values
Cs = 0.087 (Side force coef.)
Cd = 0.184

7. Lift and Drag coefficients from study
Link to study: http://www.wseas.us/e-library/transactions/fluid/2008/MGR-09.pdf

8. Results
The lift coefficient of a tennis ball is greatly affected by the spin on the ball.
The speed of the ball has a greater impact on the drag coefficient than the spin
at high speeds.
Differences in the drag and lift coefficients between the study and Star CCM+
models are due mainly to the complex surface roughness of the ball.
Differences in the material, size, and weight of the ball also affect the flight of
the ball.

9. References
https://youtu.be/v7gQ-vySQMk?t=46
https://en.wikipedia.org/wiki/Backspin
https://en.wikipedia.org/wiki/Topspin
http://www.wseas.us/e-library/transactions/fluid/2008/MGR-09.pdf