Theory of the Golf Ball Dimples

[aerohead]

Originally Posted by MobilOne

What is the ground effect referred to above?

I think that the context of the remark is about the phenomena an airfoil experiences near the ground,where the wing appears to float on a cushion of air captured between the wing's bottom and the ground.
Landing a Piper Cherokee which has the 'Hershey Bar' wing exhibits this effect.It's hard to get the plane to settle onto the runway.
Wing In Ground Effect (WIG) aircraft take advantage of it,developing remarkable lift.A neighbor's friend ran an airline into South America and flew in ground effect a few feet above the Amazon River to save fuel.

[MobilOne]

Along he same line, I remember reading, a long time ago, that during WWII, the Germans, flying from somewhere in Europe, (Germany or Spain) had scheduled passenger flights between Germany and Buenos Aires using the Condor passenger plane. The pilot told how they flew 25 feet above the ocean with the engines throttled back and covered great distances that way.

That being said, I see no way that the "ground effect" has anything to do with a golfball unless it is flyng about 1 inch off the ground.

[LittleBlackDuck]

Originally Posted by MobilOne

Along he same line, I remember reading, a long time ago, that during WWII, the Germans, flying from somewhere in Europe, (Germany or Spain) had scheduled passenger flights between Germany and Buenos Aires using the Condor passenger plane. The pilot told how they flew 25 feet above the ocean with the engines throttled back and covered great distances that way.

That being said, I see no way that the "ground effect" has anything to do with a golfball unless it is flyng about 1 inch off the ground.

Harking back a lot of years to my aerodynamics lessons in uni and when I learned to fly, ground effect is primarily an interaction between a lifting body and a flat surface below it, and is also somewhat related to wingtip vortices. In the context of cars on roads it is somewhat an irrelevancy unless you are looking to generate downforce or lift in significant quantities. Given that fuel economy is the main agenda item here, ground effect will not have any significant influence either way.

Simon

[freebeard]

Geez, what a dry, humorless bunch. I said it was a joke at Permalink #11

Well, it spoils the joke but Okay:

https://...

The joke is that it's really...ground turbulence.

QED (quod erat demonstrandum or it is proven) was the punchline, because it wasn't.

Originally Posted by MobilOne

Along he same line, I remember reading, a long time ago, that during WWII, the Germans, flying from somewhere in Europe, (Germany or Spain) had scheduled passenger flights between Germany and Buenos Aires using the Condor passenger plane. The pilot told how they flew 25 feet above the ocean with the engines throttled back and covered great distances that way.

I heard the same story, but it was about the Dornier Do X. It made one flight to Brazil in 1931 and returned via Newfoundland. What a DoX in ground effect might look like:

https://en.wikipedia.org/wiki/Dornier_Do_X

Wikipedia shows one trans-Atlantic flight for the Condor:

It was the first heavier-than-air craft to fly nonstop between Berlin and New York City (c.4000 miles), making the flight from Berlin-Staaken to Floyd Bennett Field on 10/11 August 1938

And that they were operated by two Brazilian airlines. The Do X had to be re-engined to reach a ceiling of 500m, the Condor reached 3000m, limited by the unpressurized cabin.

[Vman455]

Originally Posted by ChazInMT

I just refer folks to This Article on Hot Rod dot Com from a guy who is as close to an aerodynamic guru as we'll ever know. Towards the bottom he states under the caption

"Aero Stuff That Doesn’t Really Matter
In addition to our list of five tricks that almost always work, here are some things A2 customers might want to try that are really a waste of time.":

"Golf-ball dimples: They do not work on cars, regardless of the scale of the dimples, unless your car is a 1.68-inch-diameter sphere spinning through the air with no ground plane."

So, Boom. Fantasize about dimples working all you want. Greater minds than ours have said "Fuggedda Bout It". 9 Years ago no less.

Originally Posted by MobilOne

What is the ground effect referred to above?

Not to disparage the tangent into airplane ground effect above, but what Eaker was referencing is the ground plane effect on a streamlined half-body, like a car. Last two entries on this handy little graphic, from his own A2 website: