Dimples are great for golf balls. Why not for wings also?

Dimples increase the glide path of golf balls 50% or more apparently by reducing drag by reducing the boundary layer. But why are they not used for wings? Wouldn't dimples also reduce the boundary layer for wings, or would the wings have to rotate to realize this benefit?

Let me know your opinions.

Should truly high performance wings have more elaborate cross sections to more effectively manage the boundary layer and therefore increase their lift to drag ratios?

Or do dimples reduce lift as much or more than they they reduce drag? Or are manufacturers a little perplexed about how they would manufacture dimples in wings? In short, why don't we have them?

-- There's nothing like a good esoteric question like this to make you sound like you might really know something about something without really trying!!!

Thanks,
Wayne German

The Discovery channel ran a show on an old Air Force project along the same lines.
As I recall the skin of the aircraft was setup with shark-scale- inspired channels. To run any undesirable vortices through the wing[8D]
Then they discovered that any performance gain they had was negated if the surface wasn't perfectly clean.
Now I know why they clean golf balls

The German Junkers, were corrugated metal

http://www.rcuniverse.com/forum/m_13...tm.htm#1384435

Wayne,

Many wings have turbulators to achieve the same benefit that dimples deliver for golf balls. Dimples reduce drag on a golf ball by forcing the flow in the boudary layer to turn turbulent, which keeps the boundary layer attached longer than it would be if it were laminar. This is just what turbulators on a wing do. On a wing, we know primary direction in which the air will flow, so the turbulator can be a strip of tape of the correct thickness, instead of dimples.

banktoturn

You are a bit late -- the question has already been asked & discussed here.

Dimples actually increase drag on the forward surface of the ball, but significantly delay seperation on the backside of the ball. If you could get a golf ball to work without spinning, the best solution would be a clean smooth front face & dimples, or turbulators of some other description, on the back side.

Various aircraft already use this technology through the employment of vortex generators of various configurations, situated aft of the center of pressure.

Read the long thread linked in Starwoe's post for considerable background.

Britbrat, you're close but not quite spot on. The proper location for a non rotating sphere would be a band of dimples or other turbulating trips located around the vertical waist of the ball where the air is expected to turn around and start coming back inwards in the wake of the ball. That's where the air needs to be invigorated to help delay the separation. Once it's onto the backside the turbulent boundry layer will hold it on with or without further dimples or other turbulation trips. But if you only have dimples or other trips on the rear side of the ball the air will separate into a larger bubble before it reaches the trips and the turbulators won't be able to do anything about it. The idea is to force a thin turbulent boundry layer to form BEFORE it is needed so it acts to hold the upper flow in closer contact. Just how much earlier is open for experimentation and debate.

You are quite right. I wasn't clear enough in my post -- in my mind, for simplicity of explanation, I was thinking dimples from the equator back. Which is the same thing as you described, except that at some point aft of the equator they are wasted. In reality, I didn't say anything like that. []

OK-- so how many dimples are best -should the pattern be exactly even --AND
are deep holes better than shallow ones .
If you think that is is not open to debate - you don't play golf
should the mass of the ball be centralized or distributed around shell- for longest flight?
for best control?
Is a liquid center better?

You make that sound like it's a bad thing???

nope - it is a required taste or lack thereof.

Ask Titleist, or Dunlop, or Ram, or Top Flight, or Ultra, or -----------!!!!!;

Centrallized for higher spin rate, but more rapid deceleration

Perimeter for slower spin, but longer-lasting spin

No

Frankly I think that solid core with lots of the nice fine tan rubber wound around it is best. That way I can cut them open and unwind the light rubber for motors for a whole squadron of micro indoor Parlour Mite free flight models. Rubber in golf balls.... what a waste of a precious commodity.....

did you prefer the gutta percha balls when you were a lad?

I have actually played golf with one of those, but I have to agree with BMatthews that the rubber wound ones were the ultimate source of tan rubber. They made really cool humming sounds when stretched across the handlebars of your bike.

Sometimes there were surprises inside those gems. When I was a kid, one night I was unwinding a ball in bed (don't tell mom) & when it was fully unwound -- aside from miles of rubber band, there was a funny squooshy ball in the middle [8D] -- so I poked & prodded it until something gooey [:'(] leaked out all over the bed [X(] (please don't tell mom). In the dead of night, I sneaked the sheets down to the laundry room & re-made the bed [&:]. My mother was really pi$$ed [>:][>:][>:] at the mess when she discovered it, but nobody knew a thing about it.

Sorry Mom.[&o]

I am beginning to wonder if some here may not have received the Victoria Cross from -- herself----

Nah -- the gutta balls were my grandfather's. The rubber-wound jobs were mine.

I found the liquid filled ones too. There was a reason for these but it's probably lost in golf ball lore.

Anyway, can we all get back to the dimples?

Whose dimples?

britbrat wrote: Yes, but that was for structural reasons, not aerodynamic. If possible the corrugations were aligned along the airflow.

Yes, but on the other hand the spinning is a good thing because it gives rise to the Magnus force which modifies the flight path of the golf ball (usually increasing the range and causing the ball to fall towards the ground with less forward velocity, thus reducing the ground roll)

/Red B.

Uh--- Red, britbrat didn't write anything about the Junkers -- wrong attribution [&:]

You are correct re. the magnus force. If you look at my post, it said, "IF you could get a golf ball to work without spinning ---"

Sorry about that Britbrat!

It was CHassan who wrote about Junkers

/Red B.

What about BMatthews' dimples?

You guys are all close, but are missing some parts. Yes, the dimples are used to make the boundary layer turbulent. But why? Yes, turbulent boundary layers stay "attached" to the surface longer. Why do you want this, because a golfball is a sphere, and it has a lot of "BASE DRAG"...like a semi truck. To reduce this base drag, you want the air to stay attached to the surface as long as possible down the back side of the sphere or ball. An airfoil has no, or at least negligable, base drag. If fact, the airfoil shape is designed for air to stay attached to the upper surface. This creates lift. When air tears off the upper surface, the lift is spoiled (hence the term spoilers).

Anyway, model's wings are almost always laminar because of the low reynolds numbers. Yes, people put trip strips and sandpaper on airfoil models to simulate turbulent boundary layers such as those found on full scale, large airplanes for wind tunnel and other testing.

So tell us something new