Date:         Thu, 21 Jan 2010 09:10:03 -0600
Reply-To:     Jim Felder <jim.felder@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Jim Felder <jim.felder@GMAIL.COM>
Subject:      Re: van aerodynamics, was Re: BenT's dream vanagon now for sale
In-Reply-To:  <24145160.23407.1264085131762.JavaMail.mcneely4@127.0.0.1>
Content-Type: text/plain; charset=ISO-8859-1

Another possible improvement that removing the luggage rack could make
AERODYNAMICALLY (and not in any other way, such as utility) is that
the front of the van would have "a finer point of entry" and smaller
"frontal area" which I am told aerodynamicists are always looking for.
From what little I know about aerodynamics, removing that six inches
up front and moving it back to mid-cabin would probably be an
aerodynamic improvement. The discussion, even if I knew what I was
talking about, would still be academic because of the vanagon/westy''s
many other aerodynamic shortcomings.

I agree with the poster who said that the seals would probably not
protect from the elements with the front removed.

One of my one-of-these-days projects is to create a cover for that
luggage sump up top, hinged at the front so that if you filled it with
stuff, the thing would act as a deflector over the cargo. I even
picked up a front fiberglass section from Unca Joel once to fulfill
that project with without messing up my car in the process of
experimentation. Haven't gotten too far with it yet.

Jim

On Thu, Jan 21, 2010 at 8:45 AM, Dave Mcneely <mcneely4@cox.net> wrote:
> Actually, Alistair, you are the one who said that common sense was
> worthless here (what you really stated was that I didn't know what I was
> talking about, a criticism that was put in an insulting manner and was
> unnecessary, as I had already stated it myself concerning my lack of
> knowledge about aerodynamics).  Now you are drawing on common sense
> yourself, which is fine with me.  You are probably right that the brick
> shape is the biggest problem with the van, as it is with other vans.
>
> If the luggage rack does contribute a major drag that the "bunny camper"
> avoids, why would it not be better, if a luggage rack is needed, to
> simply put a bar rack on that vehicle when needed, leaving it off for
> other driving?  Of course, the point is moot, because such campers are
> not available to most of us.
>
> Your explanation and that of others concerning the "hole" of the luggage
> rack leads me to wonder if placing cargo in the rack, even if it
> protrudes upward a fair bit, is no worse, aerodynamically, than leaving
> it empty.  Your thoughts on this?  After a low gas mileage experience on
> a very hot and extremely windy drive across western Oklahoma and the
> Texas Panhandle with dry bags up there, I have avoided putting stuff in
> the rack.  Maybe there is no particular reason to do so.
>
> David Mc
>
>
> On Wed, Jan 20, 2010 at 11:56 PM, Alistair Bell wrote:
>
>> couple of things,
>>
>> Chris- yup, the underside is a mess. height ride shouldn't make that
>> much diff. Lowered race cars with damns and skirt etc aside. Thinking
>> about it, maybe higher vans would suffer less drag underneath,
>> (perhaps less ground effect drag).
>>
>> Dave - hard to explain all in short form. But what you are looking
>> for in an aerodynamically slicker shape are gentle transitions in air
>> pressure. In the vanagon, if one could colour the air around the van
>> as it moves, red for high pressure, blue for low, then you'd see red
>> at front, blue at rear, and the various hues between. having the pop
>> top the way the bunny van had it would be, IMHO, in a region of lower
>> air pressure than the front of the van . maybe think of it as
>> "filling in a space". I'd even make a beer bet it contributes less
>> drag than the standard pop top
>>
>> the biggest drag in the van is the low pressure at the rear. I'd
>> guess it dwarfs any other factor.
>>
>>
>> Its all best guesses, but as others have said, common sense seems to
>> fail in fluid dynamics.
>>
>>
>> alistair
>>
>>
>> On 20-Jan-10, at 10:08 AM, Chris S wrote:
>>
>> People tend to pay attention to what they see and ignore what they
>> don't. If the top of our Vanagons looked like the underside we'd do
>> something about it. There's quite a bit of airflow and consequently
>> drag generated there, especially in the taller vans, and that presents
>> a big opportunity for improvement.
>>
>> 2010/1/20, Alistair Bell :
>>>
>>> Not so fast there DM, we've hashed  this before :)
>>>
>>> Leaving aside the big low pressure area behind the van, its seems
>>> from the limited info out there, that the luggage rack on a standard
>>> westy is a bit of a drag.
>>>
>>> See the pics here:
>>> http://shufti.wordpress.com/2009/11/10/vanagon-bustle/e349/
>>>
>>> alistair
>>>
>>>
>>>
>>> On 20-Jan-10, at 7:22 AM, Dave Mcneely wrote:
>>>
>>> Though our vehicles are far from aerodynamic, I would think this
>>> would
>>> be much less so.  David
>>>
>>>
>>> On Wed, Jan 20, 2010 at 9:18 AM, Alistair Bell wrote:
>>>
>>>> yes, makes you wonder about possibility of water/wind ingress when
>>>> driving.
>>>>
>>>> alistair
>>>>
>>>>
>>>>
>>>> On 20-Jan-10, at 6:13 AM, Dave Mcneely wrote:
>>>>
>>>> Has  a poptop, but no luggage rack.  I've never seen one like that.
>>>> That's a lot more interesting than the playboy bunnies on the side.
>>>>
>>>> David
>>>
>>
>>
>> --
>> Chris S.
>> Disclaimer: "Death and serious injury may occur"
>