Aerodynamics in Sports Equipment, Recreation and Machines - Curveball

Does a Curve Ball Really Curve?

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Spinning (Backspin) Baseball in a Water Tunnel
Note how the Flow Reacts When the Dye Hits the Baseball's Seams

More than 100 years ago a young boy named Arthur Cummings (nicknamed "Candy") became very interested in the game of baseball. He started pitching clam shells on the beach near his home. He found that by holding the clam shells a cerrtain way, he could make them curve. He hoped he could play on a baseball team and make a baseball curve, too.

Finally, in 1867 Candy Cummings, 18 years old, became a pitcher for the Brooklyn Excelsiors baseball team. He started trying his new pitch. He threw the ball snapping his wrist as he released the ball. The ball curved again and again. The batters could not hit the ball! Candy Cummings is now in the Baseball Hall of Fame as the inventor of the curve ball.

Some people still didn't believe the ball really curved. There were several tests to see. Still, no one could agree that it really curved. Finally, in 1982 the Massachusetts Institute of Technology did some testing that showed that the ball really did curve.

The curve can be explained. As the pitcher throws the ball he twists his wrist. The ball spins forward. This causes higher air pressure on top of the ball. This causes the ball to curve down.

Gravity adds more pressure in the downward movement of the ball. The ball travels 60 feet and can drop as much as 3 feet. No wonder it is so hard to hit!

Over the years pitchers have developed several different curves:

Roundhouse - Curves down and to the outside of a right handed batter.

Screwball - Same as the roundhouse except the ball curves toward the batter.

Slider - A ball thrown hard, with a twist, that slides to the right or left, but doesn't drop.

Sinker - Thrown without a spin; does not move right or left; just drops (sinks)

Knuckleball - No spin, low speed; no one can guess where it will go!

In less than a half a second after the pitch the batter must decide to swing or not. Now you can see why batting is so difficult! A pitcher is called an artist, but with velocity (speed), air pressure and gravity to think about, maybe he is more like a scientist!

If you'd like to see some of our students practicing different pitches click here.

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