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Re: Aerodynamic's and Dimple tape

To: "Clay, Dale" <Dale.Clay@mdhelicopters.com>,
Subject: Re: Aerodynamic's and Dimple tape
From: "Nafzger" <nafzger@vtc.net>
Date: Tue, 13 Feb 2001 14:19:52 -0700
Dale,
 You and I came from the same school. I have felt for sometime that getting
out of the air is more important than getting in it.
 I read an article written by of all things a fisherman, who had run some
experiments with his car top boat. He claimed to get better gas mileage on
the run to his favorite fishing hole when he put the boat up with the
transom forward.
Howard
----- Original Message -----
From: "Clay, Dale" <Dale.Clay@mdhelicopters.com>
To: "'Keith Turk'" <kturk@ala.net>; "Dave Dahlgren" <ddahlgren@snet.net>
Cc: <land-speed@autox.team.net>
Sent: Monday, February 12, 2001 9:00 AM
Subject: RE: Aerodynamic's and Dimple tape


> Hi Keith (and all),
>
> Just got back from a month in Europe and I'm trying to catch up on all the
> e-mail (over a 1000 from this list alone!!!)
>
> Interesting site, I've seen this before on A/C.  Did your friend talk
about
> how they determine where to locate the tape?  Do they use yarn or ink
(or?)
> to determine where the flow trips?
>
> I saw a brief article once in a aviation magazine about a tape used to
help
> attach flow around curves.  The tape had tiny inverted NACA duct shaped
> bumps (i.e. sticking up from the tape surface).  The rows were offset from
> the previous row by half their width.  Unlike a normal NACA duct, the bump
> started at the wide end of the "duct" and got taller toward the narrow
end.
> When the air spilled off the first bump it would be lined up with the ramp
> of the next row.  Seemed like a very ingenious idea.  Don't recall the
name
> of the company and I've never seen any further mention of it, has anyone
> else?
>
> If you go to the Corbin racing website (www.corbinracing.com) and check
the
> pictures of their "Privateer" you'll notice that their tail section has a
> series of golf ball like dimples.  Corbin is very switched on to
> aerodynamics, check out the back half of this bike, clearly they're
thinking
> ...
>
>
> One thing many people new to aerodynamics underestimate is how important
the
> closing shape is.  If you can keep the flow attached (and relatively
> non-turbulent) as far aft as possible drag can be reduced a lot.  A
vehicle
> that throws up a big roostertail has poor aerodynamics.  The smaller the
> wake the less energy imparted to the airflow.  If the taper angle towards
> the rear exceeds 7 degrees it is very difficult to keep it attached
without
> other aero aids.
>
> Dale

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