we really should use your front aero westy roof rack replacement piece to
make a mold,
then make fiberglass reproductions of what you have there Roger.

----- Original Message -----
From: "Roger Whittaker" <rogerwhitt1@GMAIL.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Friday, September 26, 2008 11:31 PM
Subject: Re: Aerodynamics and the Westie luggage rack, etc..

> dear fronts piece wanters
>
> you guys all laugh at my millage #'s and say they are untrue ...
> oh well what ever --
> i know the 1.6 TD achieved 35-38 miles to the gallon and
> i have yet to take a significantly long journey with the new 1.9 TD that
> replaced that tired little motor
> and i know you also laugh at my speed claims ...
> yet i just re-listened  to the voice diary and in one point of the trip i
> had forgotten to shut off the digital recorder
> it captured a conversation between wife and i regarding keeping speed at
> or
> around 75 MPH
> so i would not get a ticket --
> several times on very long stretches of # 10 East bound
> i had to tune it down a little as i creeping into the 90MPH zone
>
> doubt-laugh- scorn - no worries
> it was simply my experiance ...
> with that nifty fronts piece in place on our
> 1989 5 Speed California Turbo Diesel
> yours
>
> On Fri, Sep 26, 2008 at 10:18 PM, Andrew Grebneff
> <goose1047@gmail.com>wrote:
>
>> On Fri, Sep 26, 2008 at 10:31 PM, Don Hanson <dhanson@gorge.net> wrote:
>> > I did some low budget research about aerodynamics, read up on all the
>> > sources I could find, etc.  So I know a little, but I certainly can't
>> spout
>> > data or numbers, just general principals.
>>
>>
>> Aerodynamics really only come into play at above 110kmh (~70mph).The
>> vehicle may not feel as though it's run into a wall above that speed,
>> but your fuel bill will suggest otherwise, almost no matter what
>> vehicle (figure that phrase out if you can).
>>
>> That's probably why the top speed of a 25hp (the so-called "36hp"
>> engine) Split will top out at 110kmh, empty ot with a tonne of cargo.
>>
>> Modern vans still have external gutters, but that's because they have
>> a large roof area and concealed gutters couldn't cope with decent
>> rain... and of course it would be expensive (anda  rust trap) to put
>> concealed full-length gutters into one.
>>
>> The rear of a vehicle is important in drag calculations. A vehicle
>> with a sloping back roof and tail (eg a real Beetle) will have a poor
>> drag coefficient, because there is no separation of airflow over the
>> vehicle from the air behind it, causing a relarive low-pressure area
>> behind the entire rear surface of the vehicle, from roof high-point to
>> bumper. That's why the more aerodynamic cars have a sharp lip on the
>> back of the trunk edge, and probably why T3s have a very good CD (and
>> a T2 has a better CD than an E-Type Jaguar)...
>>
>> Of course, for a given shape, the larger the frontal area, the more
>> overall drag there will be, as you are trying to push a larger surface
>> through the air (which is a fluid). Take a T3 and double its size in
>> all dmensions and you'd be increasing the drag 4 times. So take this
>> into account if you're widening your bus by 20cm and want to retain
>> what we laughingly call its fuel-economy.
>>
>> ... the rear lip causes separation of the airflow over the car from
>> the turbulent air trail behind, reducing overall drag. It probably
>> also creates a little downforce at the rear, but it wouldn't be
>> significant.
>>
>> Putting an airdam on the front, IF the dam is windtunnel-tested... and
>> believe me, most are NOT), can decrease drag by reducing the amount of
>> air going under the car (which also, by being compressed as it paasses
>> under the car, which is acting as one side of a venturi, produces
>> lift, which is most noticable at the front). However the airdam itself
>> adds frontal area, which increases drag... so a properly-designed
>> airdam is a compromise.
>>
>> Rear spoilers are supposed to work by forcing air upward as it passes
>> over the tail, which results in downpressure on the car's tail. That
>> is the ideal... again, as with airdams, most "spoilers" are just
>> eyecandy and have only one effect... increased drag.
>>
>> Sideskirts are only functional on cars utilizing radical
>> "ground-effect" for downforce eg the banned Formula 1 cars.
>> On a road car there is nothing to suck air out from under the car, so
>> skirts have nothing but esthetic function... and are one more thing to
>> have to repair (as well as being rust-traps, as are most plastic
>> addons eg spoilers).
>>
>> Just as well that parentheses don't cause rust, or this mess
>>
>>                age
>>
>>                      would be fall in g  t   o
>>
>>                                                         pi
>>
>>
>>                                                                e
>>
>>
>>                                                                    c
>>
>>
>>
>>
>> e
>>
>>
>>
>>
>>  s
>>
>>
>>
>>   .
>>
>>
>>   .
>>
>>
>>   .
>>
>>
>> --
>> Andrew Grebneff
>> Dunedin, New Zealand
>> Fossil preparator
>> Mollusc, Toyota & VW van nut
>> Temporarily in Calgary, AB, Canada
>> <goose1047@gmail.com>
>>
>
>
>
> --
> roger w
> There are two kinds of jobs in the world:
> Picking up garbage and telling people things.
> Successful people do both, with the same good attitude. (riw)
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