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If the bumps on golf balls are so good at improving the the aerodynamics of a golf ball why don't airplanes have the same texture?
- Everett Vacek (age 18)
Batavia, Illinois, USA
I won't be explaining why the dimples on golf balls help golf balls to travel further, but if you'd like to read up more about that, you could go to the webpage I linked below.
The quick answer to your question is that golf balls (spheres) and airplane wings (streamlined) have different shapes, and thus have different forms of drags.
The most dominant form of drag on spheres is caused by pressure--which can be reduced by the dimples.
However, for more streamlined shapes (such as the airfoils used on wings), the dominant form of drag generated is called skin friction drag. There is still pressure drag present but it is not as significant as the skin friction drag.
This is because streamlined shapes create a much more gradual adverse pressure gradient. The gradual gradient promotes attached flow (of air) much further along the body that eliminates or delay the flow separation. The resulting wake is therefore very small and generates very little pressure drag. With little pressure drag, dimples would not significantly improve the aerodynamics of a streamlined shape.
This webpage gives a more detailed answer to your question: http://www.aerospaceweb.org/question/aerodynamics/q0215.shtml
(published on 10/12/2011)
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