Date: Sun, 29 Jul 2007 13:10:37 -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: Power output of actual vans? (long)
In-Reply-To: <934917.30048.qm@web33506.mail.mud.yahoo.com>
Content-Type: text/plain; charset="US-ASCII"
Aero-wise, perhaps very little.
Tire drag - wise, perhaps significantly.
I've got this friend who always monitors his fuel mileage, in all his cars,
vanagons etc.
With an older Loyal Subaru wagon he gets around 24ish to up to 26 mpg on the
highway.
He has this cute as could be little trailer that pops into a fully deployed
tent with bed already made, in like one step, like in 30 seconds - cool
little thing.
Very small profile, only weighs ... a few hundred lbs, not heavy at all.
He says it's a nearly 4 mpg penalty to tow that little thing, which seems
high to me, but I don't doubt him.
Tire drag on a trailer can be significant. I bought a utility trailer up in
Port Townsend Wa and noticed immediately that it 'towed hard' ....noticeably
harder than the u-haul trailers I had rented and towed with the same turbo
diesel vanagon.
I got 'real trailer tires' for it - made all the difference in the world.
They also happened to be quite tall, narrow 15 inch trailer tires, which
seem to me like they'd roll pretty easily.
My friend's mini tent trailer has tiny wheels and tires on it - wonder if
that's a factor.
But basically, towing a small thing behind a big box should not be much aero
penalty at all.
I towed a trailer loaded to the max, and stuff inside the van like crazy,
And stuff on the roof ......a syncro westy with an SVX engine....and a
loaded open trailer, stuff piled high. I got 16.5 mpg ....not bad at all I
don't think, considering the size of the engine ( 3.3 liters, 230 hp ) and
the load, and the trailer full of junk, all very useful junk....depending on
how one is about things that you 'just might need someday.: ( ! )
Scott
www.turbovans.com
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Robert Keezer
Sent: Sunday, July 29, 2007 11:56 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Power output of actual vans? (long)
I wonder how a small 4 foot by 4 foot box
trailer affects the drag behind a Vanagon? Any
info?
Robert
1982 Westfalia
--- Frank Grunthaner <FrankGRUN@AOL.COM> wrote:
> In a message dated 7/28/07 2:47:37 PM,
> albell@UVIC.CA writes:
>
>
> > Finally a worthwhile discussion :)
> >
> > Frank, hats off on your undercarriage work.
> Definitely a do-able
> > solution. The rear low press problem is
> harder. Instead of trying to
> > fair that area how about an attempt to "curve
> the flow" in there?
> > While not nearly as effective it may be more
> practicable. I'm
> > thinking of wings/winglets on top and sides.
> We've seen some full
> > width top wings and the smaller deflectors
> (linked posted on list a
> > few years ago, NZ? firm making small
> deflectors).
> >
> > A splitter also may be effective. Flat panel
> perpendicular to rear
> > hatch, length to be determined.
> >
> > I have a spare small water tunnel that my
> revell Vanagon model would
> > fit in. Would be useful for flow
> visualization and perhaps some
> > scaled drag values.
> >
> >
> > Alistair
> > Alistair,
>
> Good idea. The Revell kits are very accurate.
> You would have to fill it with
> a hydrophobic fill to make certain there were
> no spurious flow paths. Bees
> wax! The deflector would at first thought
> increase drag, but the energy release
> by eliminating or backfilling the low pressure
> zone should overcome any drag
> addition. I like the idea of the liquidics test
> with some marker streams. I
> believe that there are some interesting fluoro
> emitters when excited by turbulent
> flow as well.
>
> BTW, the pressure characteristics at the back
> of the van are very complex. A
> partially opened hatch still gives rise to a CO
> increase inside the van if the
> windows are closed.
>
> Frank
>
>
>
>
> **************************************
> Get a sneak peek of the all-new AOL at
> http://discover.aol.com/memed/aolcom30tour
>
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