Date: Sun, 29 Jul 2007 16:36:39 -0700
Reply-To: Scott Daniel - Shazam <scottdaniel@TURBOVANS.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Scott Daniel - Shazam <scottdaniel@TURBOVANS.COM>
Subject: Re: Some aerodynamic ideas..
In-Reply-To: <f05100305c2d207b92797@[218.101.117.41]>
Content-Type: text/plain; charset="US-ASCII"
Re aero outside mirrors....
Check out what Ferrari has done on some models.
The outside mirror is on two nicely shaped pylons....so the main body of the
mirror is perhaps 3 or 4 inches away from the body of the car.
That probably is a very good compromise for having the mirror outboard
enough to be really useful, and minimum aero penalty.
And I wouldn't be surprised if there was even a tiny bit of downforce
designed in,....
Joking somewhat, but not entirely.
On van shape overall, between egg shaped and rectangular.
Its all a matter of how much you want to design for low drag, and how much
you want to design for max interior room for set exterior dimensions.
The squarish ones obviously had interior useful space more in mind than pure
aero.
Personally, I *really * appreciate a vehicle that doesn't blow around in
gusts too much, is very quite at speed ( like 80 ) and low drag for fuel
economy is a give for desirability.
Personally I'd compromise 30 % on interior room to gain 30 or more % in low
drag, and resistance to cross winds and gusts.
As you succinctly and accurately say here :
That's vans... the idea of maximized interior space is
diametrically-opposed to the ideals for aerodynamics.
That's it all right....diametrically opposed requirements, or goals.
In traditional 'linear' thinking the best we can do is optimize the
trade-offs,
Until some new breakthrough comes along though, that is.
Perhaps internal fans that feed air to the body work that trick the boxey
shape into 'acting' like a smoother one ? .....
There is always a breakthrough in the future, waiting to be discovered.
All good thoughts Andrew.
We here in the US might be hard pressed to picture some of the models you
name. Either they have different model names here or we don't get them.
I was massively impressed with a 95 Nissan Quest van recently. . Didn't
have the interior room or even intent of a vanagon, so not quite comparable,
but in terms of vehicle dynamics and aerodynamics it makes a T3 Vanagon seem
like a milk truck. ( haven't seen one of those since about the 50's !! )
Scott
www.turbovans.com
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Andrew Grebneff
Sent: Sunday, July 29, 2007 2:27 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Some aerodynamic ideas..
> The Vanagon is exactly wrong for aero-efficiency...Actually, if it were
a
>perfect square rather than a rectangle, it would be worse, but..
And the Poms call them "wedges"... guess they don't know what the word
means.
> So, some of the things that could be done for better slippery...
>
> A front splitter would be about the easiest thing of all. A splitter is
>just a 'shelf', a flat projection off the front, parallel to the ground.
In
>essense a splitter fools the air into thinking the vehicle is much longer
by
>stacking up air on the top of the splitter. A splitter would also reduce
>the airflow under the van. Since we probably wouldn't be looking for
>'downforce', limiting the flow under the van would reduce the turbulence
>there somewhat.
> Flush windows would be a help also, and do-able.
I've seen a Bay with dark-tinted ?plexiglas mounted over the
sidewindows... sort of looked like a mid90s Toyota Liteace. The
sheets covered the pillars as well. Looked good.
T3s don't have flush windows, but they're less-sunken than a Bay's.
No reason a T3 couldn't be so treated, but it would mean drilling
holes in the bodywork... and even a minor airleak between body &
sheet would probably cause whistling at speed. If I wasn't so
chronically short of money (and if my bus was close to being on the
road) I'd consider it myself.
>However, the square
>front corners of the windscreen probably starts turbulence there right
there
>that continues for "a mile" behind the van
That's unavoidable with a true van. Ths closest to aerodynamic I can
think of in vanlike vehicles is Toyota's midengined "egg" Estima
(Previa/Tarago) and possibly the competition, Nissan's cynical
Serena. True vans, including the awful space-compromised FWD
offerings from Europe, generally have flattish windshields with
strong corners at the A-pillars (eg Mercedes/Freightliner/Dodge/VW
Sprinter/LT, Ford Transit, Fiat Ducato, Renault & Pugeot
competition). I doubt the longer noses of these vehicles give any
aerodynamic advantage.
>, so back to the "Entry" the
>nose...the splitter.. Raking back the front windshield would be rather
>effective also, but beyond most of us, what with the doors right there,
etc.
The T3 already has a fairly-well-raked windshield.
> Smooth wheel covers would be an easy improvement..Like those old Moon
>hubcaps..
Ugly. And of course bad for brake-cooling. Ever seen a supercar with
smooth wheels, much less hubcaps?
>Mirrors that didn't stick way out would help some also.
Again, unavoidable. You need big mirrors for proper rear-vision. Best
you can do is fit mirrors with a deeper-dished housing, say
Japanese-market Hilux.
> But, given the shape of a van, the job of significantly improving it's
>aerodynamic coefficient of drag would be....daunting..
That's vans... the idea of maximized interior space is
diametrically-opposed to the ideals for aerodynamics.
As to the rear, perhaps a splitter under the tail & a
properly-designed roof-spoiler eg Projektzwo T3 or Mazda's 90s Bongo
(also sold as Ford Spectron). Not that either spoiler has been
tunnel-tested... though I have considered widening & fitting a Bongo
item.
--
Andrew Grebneff
Dunedin
New Zealand
Fossil preparator
<andrew.grebneff@stonebow.otago.ac.nz>
Seashell, Macintosh, VW/Toyota van nut