| Re: [GMCnet] Windshield Visor [message #97696] |
Sun, 29 August 2010 07:48  |
Gary Casey
Messages: 448
Registered: September 2009
Karma: 0
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There was a post (not the one below) that suggested that a visor reduces
aerodynamic drag. The high force exerted on the visor certainly suggests the
opposite. High force = high drag. Well, maybe if it were a wing it would mean
lift, but I doubt it. They certainly keep the sun out and probably look good,
but reduce drag? I don't think so.
Gary
From: Steven Ferguson
You need to talk to Jim Bounds about how to correctly install a visor.
If you don't do it right, you will join the ranks of GMCers who have
really pissed off those following them when chunks of their ripped of
visord hit thier cars.
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| Re: [GMCnet] Windshield Visor [message #97712 is a reply to message #97696] |
Sun, 29 August 2010 10:35  |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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Gary,
Your correct. the visor can induce drag.I'm talking about the ones for the
GMC.
Only way to reduce it is to open up the gap to allow more air to exit
You can go to our site and go to instructions and see what we suggest to
trim to decrease the drag.
If you look at the visors on large trucks, you will see that the inlet is
equal to the inlet and the visor act as baffle and can reduce drag. Our GMC
units will not unless we design it like the big trucks.
On Sun, Aug 29, 2010 at 5:48 AM, Gary Casey <casey.gary@yahoo.com> wrote:
> There was a post (not the one below) that suggested that a visor reduces
> aerodynamic drag. The high force exerted on the visor certainly suggests
> the
> opposite. High force = high drag. Well, maybe if it were a wing it would
> mean
> lift, but I doubt it. They certainly keep the sun out and probably look
> good,
> but reduce drag? I don't think so.
> Gary
>
> From: Steven Ferguson
> You need to talk to Jim Bounds about how to correctly install a visor.
> If you don't do it right, you will join the ranks of GMCers who have
> really pissed off those following them when chunks of their ripped of
> visord hit thier cars.
>
>
>
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] Windshield Visor [message #97715 is a reply to message #97696] |
Sun, 29 August 2010 11:12 |
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mike miller
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
Karma: 0
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| Gary Casey wrote on Sun, 29 August 2010 05:48 |
... They certainly keep the sun out and probably look good,
but reduce drag? I don't think so. ...
|
Directing air flow might cause some stress (and drag) on the visor, but, if designed correctly, it may reduce the OVERALL drag on the coach.
To explain:
I KNOW at highway speeds, a stock (no visor) coach has a low pressure area around the top and sides. This is especially true of the area where the fiberglass front cap joins the aluminum body panels. (It sucks the curtains out the window and opens the front vent on my 1973.) This is from the air being pushed "way out of the way" by the nose of the coach. At some speeds the air along the top and sides is actually flowing forward!
If a visor directs airflow into this low pressure area, it should reduce drag. A _small_ amount of turbulence would also help. (Just like on a golf ball... look it up. <http://www.aerospaceweb.org/question/aerodynamics/q0215.shtml> )
SO....
Like JimK says... Visors need to be designed/modified and installed properly.
Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo'
http://m000035.blogspot.com
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| Re: [GMCnet] Windshield Visor [message #97723 is a reply to message #97715] |
Sun, 29 August 2010 11:50 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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I think visors are like deck spoilers below wind speeds of 60 mph. About all
they spoil is a couple of 50s and a 20 or two.
Jim Hupy
Salem, OR
78 Royale 403
On Sun, Aug 29, 2010 at 9:12 AM, Mike Miller <m000035@gmail.com> wrote:
>
>
> Gary Casey wrote on Sun, 29 August 2010 05:48
> > ... They certainly keep the sun out and probably look good,
> > but reduce drag? I don't think so. ...
>
>
> Directing air flow might cause some stress (and drag) on the visor, but, if
> designed correctly, it may reduce the OVERALL drag on the coach.
>
> To explain:
>
> I KNOW at highway speeds, a stock (no visor) coach has a low pressure area
> around the top and sides. This is especially true of the area where the
> fiberglass front cap joins the aluminum body panels. (It sucks the curtains
> out the window and opens the front vent on my 1973.) This is from the air
> being pushed "way out of the way" by the nose of the coach. At some speeds
> the air along the top and sides is actually flowing forward!
>
> If a visor directs airflow into this low pressure area, it should reduce
> drag. A _small_ amount of turbulence would also help. (Just like on a golf
> ball... look it up. <
> http://www.aerospaceweb.org/question/aerodynamics/q0215.shtml> )
>
> SO....
>
> Like JimK says... Visors need to be designed/modified and installed
> properly.
> --
> Mike Miller
> `73 26' X Painted D.
> `78 23' Birchaven
> Hillsboro, OR
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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