The Murphy Builders Site

On 3 Oct 2006 at 10:32, gargus@adelphia.net wrote:

Wacky question
So now I am asking if anyone knows of any experiments with dimpled skins and fuselages on the performance of airplanes (aside from those planes pelted with hail stones)?

Do a Google search on Turbulator tape. Common for sailplanes.

---
David Parrish




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Spheres are so draggy that dimpling yields significant gains.
Aerodynamic shaping such as a long tapered tail or wing has got to be
even better.
I suspect that teardrop shaped golf balls would likely work better than
dimpled props or wings ;)
Dimple tape doesn't seem to have caught on.
Ken

gargus@adelphia.net wrote:

[quote]Wacky question

Why do golf balls have dimples? According to aerospace engineer Bob Thurman. He designs golf balls for Wilson Sporting Goods in Humboldt, Tennessee.
“The dimples are there to reduce the aerodynamic drag, that would be acting on the ball if it were entirely smooth. He explains that when a smooth ball sails through the air, it leaves a big pocket of low-pressure air in its wake. That creates drag, which slows it down. So if you can make that wake smaller, then the pressure differential goes down. So the drag force is actually reduced. The dimples do this by creating turbulence in the air around the ball. That forces the air to hug the ball more closely. So instead of flowing past it, the air follows the curvature of the ball around to the back. The result is a smaller wake, and less drag. A smooth ball when struck by a driver, would probably carry about 110 yards in the air and a well designed golf ball is going to carry 250 yards. So that's a huge difference.â€

What about pelting your airplane with golf balls? Sort of a 2 for 1 deal.

From: Ken <klehman@albedo.net>
Reply-To: <rebel-builders@dcsol.com>
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Dimpled wings
Date: Tue, 03 Oct 2006 21:11:30 -0400

Spheres are so draggy that dimpling yields significant gains.
Aerodynamic shaping such as a long tapered tail or wing has got to be
even better.
I suspect that teardrop shaped golf balls would likely work better than
dimpled props or wings ;)
Dimple tape doesn't seem to have caught on.
Ken

gargus@adelphia.net wrote:

Wacky question

Why do golf balls have dimples? According to aerospace engineer Bob

Thurman. He designs golf balls for Wilson Sporting Goods in Humboldt,
Tennessee.

“The dimples are there to reduce the aerodynamic drag, that would be

acting on the ball if it were entirely smooth. He explains that when a
smooth ball sails through the air, it leaves a big pocket of low-pressure
air in its wake. That creates drag, which slows it down. So if you can make
that wake smaller, then the pressure differential goes down. So the drag
force is actually reduced. The dimples do this by creating turbulence in
the air around the ball. That forces the air to hug the ball more closely.
So instead of flowing past it, the air follows the curvature of the ball
around to the back. The result is a smaller wake, and less drag. A smooth
ball when struck by a driver, would probably carry about 110 yards in the
air and a well designed golf ball is going to carry 250 yards. So that's a
huge difference.â€