Date: Mon, 30 Jul 2007 14:27:50 +1200
Reply-To: Andrew Grebneff <andrew.grebneff@STONEBOW.OTAGO.AC.NZ>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Andrew Grebneff <andrew.grebneff@STONEBOW.OTAGO.AC.NZ>
Subject: Re: Some aerodynamic ideas..
In-Reply-To: <00e201c7d239$53b3ce50$6401a8c0@TOSHIBALAP>
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>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.
The T3 mirror sit on longish stalks away from the body, but the shape
of the housing isn't particularly good... I think the electric ones
(I haven't seen one) are deeper?
>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.
Indeed. Long-nosed vans (eg US, Transit, Sprinter etc) are severely
compromised in interior space. Vans with tumblehome (rounded sides)
have problems too, as large items cannot be stacked right to the
widest part of the interior (this is where people who try to use
stripped-out vanlike Estimas fall foul). Likewise raked tailgate
windows. If you want the ultimate space-efficient box on wheels,
lookit the current Toyota Hiace. It retains the cabover
front-midengined design of previous Hiaces but drops any pretence of
attractive styling... the sides and tail are vertical. It has also
grown, dwarfing the earlier models.
>Personally, I *really * appreciate a vehicle that doesn't blow around in
>gusts too much, is very quite at speed ( like 80 )
The T3 shouldn't suffer particularly badly from sidewinds, but wear
in the steering, incorrect wheel offset, tires can all cause this
problem. So can bad steering alignment or a dragging brake. Mine,
with a GM V6, was very quiet... most noise was a faint rustle from
the driver's side (right) A-pillar. That was with stock mirrors;
hopefully the Hilux mirrors I'm mounting will be quiet.
>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.
Even Toyota's ultrasmooth "Egg" doesn't give good economy. I think
it's more a frontal-area thing then outright cd. Even a van that will
happily do 160kph-plus will still begin to hog fuel when it hits 110
(~70mph).
>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.
How about a pitted surface (à la golfball) to give a separation layer
for better laminar flow?
>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.
Thew Euro vans aren't sold in the US, other than the Mercedes/VW.
Like so many Nissans, the Nissan Serena is a cynical attempt to do an
Estima without the expensive mechanical layout, and is a dismal
vehicle (you can find images of any of these vehicles by Googling,
especially for Japanese used-export sites or NZ used-car sites).
Estima is the Japnese-market name for what is exported as Previa; the
first generation (1990-2002/2003) was the eggshaped midengined one,
and came in two widths; only the wide-body was exported. Side-panels
and doors (excepting tailgate) are interchangable bewteen
body-widths). Front-end styling and dashboard/doortrims were
different, and the narrow-body had several facelifts over the years;
the wide-body never did. The 2nd generation was front-engined
FWD/4WD, as is the new generation. Neither FWD generations were sold
in the US, where the Camry-based Sienna (and to an extent, I guess,
the Corolla variant called Matrix/Vibe) took over.
Other vans & peoplemovers of interest to look up are:
Nissan Caravan/Urvan/Homy (you'll see why I say Nissan copies Toyota)
Nissan Vanette
Toyota Liteace/Masterace/Townace
Toyota Hiace
Toyota Regius/Granvia
Mazda Bongo/Ford spectron (now Also sold with Nissan Vanette & Isuzu
Fargo badges!!)
Mazda Bongo Friendlee (MPV, not same as Bongo van)
Isuzu Fargo (not in production now, one generation only made)
Mitsubishi Delica
Mitsubishi Delica Spacegear
Hyundai H100 (90s-generation Delica made under license)
Daewoo Pregio (original & facelift copy Hiaces... and what a name!))
Mercedes MB100 (I suspect it's a Ssangyong desigh using Merc
mechanicals & with Hiace-derivative styling)
Mercedes Vito
(/ means same model sold under different names)
Note that many of these were produced in two or more generations.
Japanese ones were all available with 4WD and turbodiesel, some with
naturally-aspirated diesel as well. The Delica, Liteace & Vanette
went front-engined with the latest generation (apart from the
Vanette-badged Bongo). The larger Japanese vans remained true to the
front-midengined design for maximum space-efficiency.
>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 !! )
Dorta Loomis without the armor?
Thinking about rear diffusers, that wouldn't work because the
engine/exhaust would be in the way.
--
Andrew Grebneff
Dunedin
New Zealand
Fossil preparator
<andrew.grebneff@stonebow.otago.ac.nz>
Seashell, Macintosh, VW/Toyota van nut