Recent content by Roy Dale

Golf balls would have grip on the air without dimples but they have more grip as a result of them. A good analogy would be a spinning car tire. The more grip (friction) between the tire and the road the more linear force the spinning car tire generates. The more the spinning tire is pushed into...

Dimples cause the relative airflow around the ball to be stickier thus increasing surface or friction drag. It causes the relative airflow to stay attached longer leaving less wake reducing pressure drag. Because pressure drag is the most prevalent drag on the ball reducing it reduces over all...

By definition, the reaction force in the direction that the ball moves, slowing it down, is called drag. The reaction force perpendicular to the direction the ball moves, causing it to curve, is called lift. If there were a reaction force in the direction that the ball moves it would not...

Without the wing pushing and pulling on the air around it the air around it would not be accelerated, so any motion of the air caused by the wing is caused by the wing pushing on the air or pulling on the air. Once in motion pressure may go down but there would be no motion on the top of a wing...

Take an airplane that is flying through the air, the air that is generating its aerodynamic force is made up of still air. This air is not moving over the wing the wing is moving through the air. For this air to experience low pressure as a result of its increased speed it has to increase its...

The air flowing around the car is not what is turning the turbine because there is no air flowing around the car unless the wind is blowing. Luckily aerodynamic force does not require air to actually flow around an object, it only requires a difference in velocity between the object and the...

And the answer is some times not always. The best way to know is to learn the simple and accurate definition of drag and apply it to your particular circumstance. Drag is in the direction of the relative airflow that caused it. I am sure that you have heard that to move through the air you must...

Unfortunately lift has many definitions but it is most accurately defined as being perpendicular to the relative airflow that caused it. Drag is always in the direction of the relative airflow that caused it not opposite it as you said. If drag was opposite the relative airflow that caused it...

First thank you for your gracious welcome. The fact that the Magnus effect is caused by the spinning of the ball as it moves through the air is never ignored by texts or me. The spinning is ignored when determining the aerodynamic force that causes the Magnus effect. If a non-spinning ball...

Magnus effect Spinning balls moving through the air in the real world only generate drag not lift. The Magnus effect is caused by uneven friction drag around the spinning ball. The uneven friction drag is caused by the spinning ball being pushed into the oncoming air not unlike a spinning car...