spin and lift

Question
QUESTION: many discussions concerning spin and lift of a golf ball which I disagree with. many say that at a specific rpm a golf ball will reach its maximum lift. I believe this is wrong. In order to create lift there must be a difference in shape from the top surface to the bottom surface in which the air going over the top is faster than that of the lower( this creates less pressure on top thus easier uplift ) . As a golf ball is round there is no difference in the surfaces to create lift. I believe that the lift in golf is created by the angle and speed of the clubface only.

ANSWER: Hi Ted,

You're right that the air flowing over the top of the object must be faster to create lift. If a ball were not spinning, the speeds would be the same and thus no lift. However, because of the spin, the surface of the top of the ball is moving with the air flow and the bottom is moving against the air flow. Thus, more air goes over top, at a higher speed than over the bottom. The principle is the same for an airplane wing except the difference is a result of shape, not spin.

You'll find lots more info here:
http://www.grc.nasa.gov/WWW/K-12/airplane/beach.html

The dimples of the golf ball increase this effect as well.

Hope this helps.

Please visit and patronize my site.
http://www.probablegolfinstruction.com

Ken Tannar

---------- FOLLOW-UP ----------

QUESTION: I failed to mention that I retired from the Air Force so I know about wing structures and lift. What I don't perceive as substantial lift in a golf ball created by its spin. I will agree to some extent that if the wind is coming head on then the lift is somewhat increased. The same theory does not hold true for a dead calm day or a tail wind. If a Golf Ball is spinning at the end of a mechanical arm in an enclosed room and the ball is released it will not lift and take flight, it will drop straight down.

Answer
Hi Ted,

What's very different about the golf ball, however, is it has a very small surface area to mass ratio, while an airplane wing has a larger surface area to mass ratio. The gravitational force on a golf ball will always be greater than the lift force unless the backspin rate is very high. That's why golf balls always fall back down to Earth, while a play can remain in the air as long as it can maintain its speed.

I agree that "If a Golf Ball is spinning at the end of a mechanical arm in an enclosed room and the ball is released it will not lift and take flight, it will drop straight down."

Ken