Want low drag? Don't follow a template.

[JulianEdgar]

Originally Posted by aerohead

Did any of them sign off on page-195 ? The reason I ask, is that, compared to page 186, you're saying the exact opposite with respect to the principles of fluid dynamics. No continuity.

Yes of course they all read both pages. They didn't seem to have any issue - but hey, what would they know?

[JulianEdgar]

Originally Posted by aerohead

' To know and not tell makes cowards of men.' Abraham Lincoln
Okay, so what does it say specifically. Otherwise you're just name-dropping. I'm not impressed by book covers.
Perusing SAE International's website, and the PREVIEW feature for recent SAE Papers hasn't lead to any revelations in modern road vehicle aerodynamics that I can discern. Quite the contrary.

I've shown you the reference. Go and read it - and learn a great amount.

[JulianEdgar]

Originally Posted by aerohead

* Your book is written for the car enthusiast and non-engineer.
* Those of us here, with an engineering background, will find certain aspects of your investigations and conclusions falling outside the bounds of scientific rigor.
* Three times already, I've attempted to direct you towards science which would provide a much deeper insight into your experiences and interpretations. And it looks like three times it was all for naught. None of your subsequent posting reveal any hint that you spent even a pico-second with the material. Had you processed it, it would be impossible for you to cling to your folk knowledge.
* I'm in doubt that your international panel of experts actually signed off on as much of your book as you claim. I'd very much like to see what your exchanges actually were, and did some things get lost in translation between an engineer-aeronautical engineer- aerodynamicist, and a sociologist-geographer.

And journalist - you forgot about that.

We don't need to see all the correspondence from the reviewers - just look at the endorsements. You can be absolutely sure these experts wouldn't have endorsed the book without agreeing with its content!

"The best practical introduction to aerodynamics for the car enthusiast that I've seen. The author combines his own experience with published research to provide useful and reliable insights into the often bewildering world of automotive aerodynamics." Adrian Gaylard, head of aerodynamics, Jaguar Land Rover

"A really good book that should be added to the library of everyone working in automotive aerodynamics, as well as those making car aero modifications at home." - Rob Palin, former Tesla aerodynamicist

"This book covers a wealth of useful car aerodynamic information for the non-engineer." Professor Joseph Katz, author Race Car Aerodynamics

"Your book is unique! It was high time that someone covered vehicle aerodynamics through the practical eyes of someone like you." - Dr Wolf-Heinrich Hucho, the founder of modern vehicle aerodynamics

Unfortunately, from your perspective, a great deal of what you say here is either completely wrong, partly wrong or misleading. People have been sucked into it (or maybe just overwhelmed with the 'wall of noise' approach you take to debates) and so lots of misapprehensions have developed here around car aero. The Template is the most obvious of those misapprehensions.

[freebeard]

So — I'll bite: What's number two?

[kach22i]

If anyone wants to take a crack at these questions, feel free to do so.

1. Automotive; downwash is always the result of a vortex, yes, no, maybe.

2. Automotive; downwash is the byproduct of a sudden pressure change via air detachment, yes, no maybe.

I tried to do an image research on "Vortex Downwash" but only aircraft stuff came up.

Then I did a image search on "Automobile Downwash" and found the below.

2011-04-12
The New Audi A6/A7 Family - Aerodynamic Development of Different Body Types on One Platform 2011-01-0175
https://www.sae.org/publications/tec.../2011-01-0175/

[kach22i]

I found a graphic similar perhaps to something in the originally posted video.

Aerodynamic Formulae
Aerodynamics in Racing Vehicle Design | F1 Insight

Combination of lift and drag force

Just posting the image here so I can find it later.

The arrows in the video were in opposite direction maybe (different point?), but don't quote me on that. I need to go back and check it, hence depositing it here.

[Cd]

Kach : that's an interesting image.
I remember seeing those same patterns on Svens' anal probe after he tested it in the snow.
Two symetrical areas that cleared down the sides, with the center section having snow remaining.
He had guessed that this showed that there were two vortexes along the sides of the rear glass.
Looking at the CFD image here seems to confirm that.

I miss that guys humour.

[freebeard]

1. Automotive; downwash is always the result of a vortex, yes, no, maybe.

2. Automotive; downwash is the byproduct of a sudden pressure change via air detachment, yes, no maybe.

Detachment is always associated to vortexes, yes no, maybe?

A vortex is just self-sustaining ordered turbulence?

[JulianEdgar]

Originally Posted by freebeard

So — I'll bite: What's number two?

As in, the template is the greatest misapprehension here - but what is the next greatest?

Without a doubt, the significance and action of aero pressures acting on panels.

When Vman455 showed some of the measured pressures on his Prius (data that immediately contradicted much of what Aerohead spouts), I was amused to see no-one actually 'got' the contradiction (or no-one who commented, anyway). I was amused but not surprised - because the same thing happens here when I show my Insight's measured body panel pressures.

Aerohead's ideas in this area are again quite wrong, and again they seem to have been adopted widely here. And - yet again - it's because people don't make measurements - if they did, they'd soon see reality for themselves.

A good example is the person from this group who commented on my 'don't use a template' video. He looked at the Jaguar's CFD pressures (shown in the video) and had them completely reversed! That's sure some misunderstanding.

And I might add, the reason for that complete misunderstanding can be related back to the silly template - you could see that's what he was trying to build his ideas on. But crap in = crap out.

[freebeard]

Without a doubt, the significance and action of aero pressures acting on panels.

How do you get from measured pressures to significance and action? Panel orientation to direction of travel? How do you generalize that?