The preceding discussion helps us understand why CD increases with Sp, as seen in
figure 2. A ball with v − rω < vc on one side does not whip air around it as well as if it
had turbulent separation on that side. The net force from the air thus has a slightly greater
drag component. As we mentioned earlier, there is just one force on the ball from the air.
Transitions from turbulent to laminar on one side of the ball at high Sp appear to result in one
force component becoming a little larger while the other becomes a little smaller. Even for
Sp < 0.3, where the data in figure 2 were taken, some portion of the whipped air will be along
the direction of the drag force.ses