Vanagon EuroVan
Previous messageNext messagePrevious in topicNext in topicPrevious by same authorNext by same authorPrevious page (September 2008, week 4)Back to main VANAGON pageJoin or leave VANAGON (or change settings)ReplyPost a new messageSearchProportional fontNon-proportional font
Date:         Fri, 26 Sep 2008 23:31:49 -0700
Reply-To:     Roger Whittaker <rogerwhitt1@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Roger Whittaker <rogerwhitt1@GMAIL.COM>
Subject:      Re: Aerodynamics and the Westie luggage rack, etc..
Comments: To: Andrew Grebneff <goose1047@gmail.com>
In-Reply-To:  <f700b5ac0809262218k39f0ff23hc42f811e2f6b7df2@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1

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) ---------------------------------------------------------- Explore printed work at: http://www.prliving.ca/ View the growing list of video work at: http://revver.com/find/video/?query=LastonLastof&search_on=owners and ... older work at http://video.google.com/videoplay?docid=-7135104650374818257 http://video.google.com/videoplay?docid=3259745150182742364


Back to: Top of message | Previous page | Main VANAGON page

Please note - During the past 17 years of operation, several gigabytes of Vanagon mail messages have been archived. Searching the entire collection will take up to five minutes to complete. Please be patient!


Return to the archives @ gerry.vanagon.com


The vanagon mailing list archives are copyright (c) 1994-2011, and may not be reproduced without the express written permission of the list administrators. Posting messages to this mailing list grants a license to the mailing list administrators to reproduce the message in a compilation, either printed or electronic. All compilations will be not-for-profit, with any excess proceeds going to the Vanagon mailing list.

Any profits from list compilations go exclusively towards the management and operation of the Vanagon mailing list and vanagon mailing list web site.