How well polished does a glider need to be?

"Ralph Jones" wrote in message
:

On Wed, 09 Jul 2008 08:13:04 -0600, Ralph Jones
wrote:

On Wed, 9 Jul 2008 04:26:33 -0700 (PDT), Dan G
wrote:

I'm crewing this season, and no doubt my pilot will be expecting me
out at 7am with Mer in hand.

My question is (and I'm sure it's been debated before, I did search,
but want fresh input) how worthwhile is polishing?

I can understand keeping the fuselage as slippery as possible to
reduce skin drag, but I've heard that glider wings would still work as
well as possible if their surface was 40 grit sandpaper! Also take a
look at a golfball -- it's dimpled specifically in order to reduce
drag, again implying that a smooth surface may not be perfect.


There's a major difference between blunt bodies like a golf ball and
slender ones like an airfoil. Drag on the former is mostly pressure
drag, while drag on the latter is dominated by skin friction.

[snip]

I forgot one other effect of the dimples: they make lift. A golf ball
is normally hit with backspin, and the curveball effect creates a
little bit of lift, making the ball a super low-performance
glider...;-)




Hmmm, I wonder if we should take a ball peen hammer to a 1-26? I might
be on to something here....

Larry
01 Zero One

01-- Zero One wrote:

I forgot one other effect of the dimples: they make lift. A golf ball
is normally hit with backspin, and the curveball effect creates a
little bit of lift, making the ball a super low-performance
glider...;-)

Hmmm, I wonder if we should take a ball peen hammer to a 1-26? I might
be on to something here....

I think somebody must have had that idea for my club's 1-36, and I am not
at all convinced that it resulted in better performance....

--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon

On Jul 22, 7:19 am, Michael Ash wrote:
01-- Zero One wrote:



I forgot one other effect of the dimples: they make lift. A golf ball
is normally hit with backspin, and the curveball effect creates a
little bit of lift, making the ball a super low-performance
glider...;-)

Hmmm, I wonder if we should take a ball peen hammer to a 1-26? I might
be on to something here....

I think somebody must have had that idea for my club's 1-36, and I am not
at all convinced that it resulted in better performance....

--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon

Actually there was a 1-26E on W&W last year or so that was nicknamed
"The Golfball" because it sat out a hailstorm on the tiedown line.
Apparently it DID actually increase it's performance slightly!
(established by many side by side glides with other 1-26's)

-Paul

"sisu1a" wrote in message
...
On Jul 22, 7:19 am, Michael Ash wrote:
01-- Zero One wrote:



I forgot one other effect of the dimples: they make lift. A golf ball
is normally hit with backspin, and the curveball effect creates a
little bit of lift, making the ball a super low-performance
glider...;-)

Hmmm, I wonder if we should take a ball peen hammer to a 1-26? I
might
be on to something here....

I think somebody must have had that idea for my club's 1-36, and I am not
at all convinced that it resulted in better performance....

--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon

Actually there was a 1-26E on W&W last year or so that was nicknamed
"The Golfball" because it sat out a hailstorm on the tiedown line.
Apparently it DID actually increase it's performance slightly!
(established by many side by side glides with other 1-26's)

-Paul

Northeastern Colorado is "hail alley" so there are many hail dimpled
airplanes around. People selling these often use the "golfball effect" in
their sales pitches...