Golf Ball effect

[msim]

http://www.youtube.com/watch?v=CPe1kk8A65g

So, golf balls have dimples to reduce drag.
My question is if RC's would benefit from this. Would dimples reduce drag enough to make a difference?

I apologize if this was a repeat thread.

[Montag DP]

http://www.rcgroups.com/forums/showthread.php?t=1111121&highlight=golf

You would not want a dimpled surface similar to a golf ball. At best, sometimes a turbulating strip is used on the top of the wing to create a turbulent boundary layer and thus reduce flow separation at the trailing edge. This is the same effect that the dimples on the golf ball have, but on the golf ball a single turbulator strip would not work because the ball is spinning. Golf balls do not have a whole lot of surface area compared to an airplane wing, so the dimples all around the ball do not add significantly to the skin drag.

On a wing, however, only a single turbulating strip is needed (that is, if it is beneficial at all. In many cases it is not.) Making the entire surface dimpled would only increase the skin drag.

Dan

[BMatthews]

A sphere passing through air forms a wake that is very close to the diameter of the sphere. This is very draggy. The dimples on the golf ball form turbulators that encourage the air to stick to the sphere's surface for a greater distance past the waist and form a smaller wake so drag is reduced.

However our models, for the most part, are shaped so as to slice through the air and leave much smaller wakes. So other than adding turbulators to solve specific troubles there's no advantage to making the entire surface or even significant portions tubulated. Certainly making the whole surface dimpled would just add a lot of skin drag as Montague has mentioned.

For example, if you were to catapult a well streamlined airfoil shaped "bullet" (think small drop tank shaped object here) that had the same waist diameter and weight as the golf ball and it was smooth the shape would give it enough less drag due to not forming and dragging along a wake that it would easily go out and fall to the ground at a FAR greater distance than a dimpled golf ball would do for the same launch.

Another example of this wake issue is that a round rod in the wind has the same drag as a proper airfoil shape that is roughly 10 times the thickness of the diameter of the rod. So just getting rid of the wake is a huge part of proper streamlining.

[JetPlaneFlyer]

The other difference between a golfball and a wing besides the shape is the fact that the ball spins.
The spin can creates a circulation effect and therefore creates lift. Google 'magnus effect'. The dimples increase this circulation effect and so increase lift and so the ball travels further.

Wings dont spin so it dimples wont work the same way on a wing.

Steve

[BMatthews]

But they would look SOOOOO CUTE with all those dimples! :D

[Sefco]

Probably my favorite Mythbusters to date. That 11% fuel savings from the dimples comes in handy when the new Ford Taurus features dual turbos, a ridiculous 365 HP, and 17 mpg in a 4-door soccer mom car...