The Kamm research cars

[freebeard]

Fair enough. You got what I was hinting at.

[aerohead]

Originally Posted by JulianEdgar

After reading my book, Dr Hucho wrote nothing to me about a template of any kind.

He was more concerned that I didn't have a chapter on wind tunnel testing than I'd completely missed this amazing template that Aerohead ascribes to him.

What you will find in Hucho's book is this diagram:



No less than five low drag shapes, all looking different! So which one are we to pick to help us in our modifications? Depending on that, the resulting mods will have quite different shapes! And how can that be so, when we've been told here for so long that there is only one template? (Or two, I find it hard to keep up.)

1) there's actually seven if you do the elongations.
2) among the five depicted, the AST occurs five times.
3) so you're arguing against the ' template' by using the 'template' as counterfactual evidence. Very disturbing and confusing.

[JulianEdgar]

Originally Posted by aerohead

1) there's actually seven if you do the elongations.
2) among the five depicted, the AST occurs five times.
3) so you're arguing against the ' template' by using the 'template' as counterfactual evidence. Very disturbing and confusing.

One template occurs five times in the five different templates?

And five templates is really seven if you change them?

Neither point makes any sense.

[AeroMcAeroFace]

I think it is like a magic eye picture, you have to keep looking to eventually see it and only certain people can see it.

[aerohead]

Originally Posted by JulianEdgar

One template occurs five times in the five different templates?

And five templates is really seven if you change them?

Neither point makes any sense.

1) It helps to un-nest the images into their individual elevation and plan-views. I probably published all of them in 2007. Don't remember.
2) The VW-Drop Shape is full-length already, so other than lowering it ( if that actually helped), or installing wheel fairings, there's no additional drag reduction available. And if you'll examine the 'windscreen' area, it might develop the ' intolerable refraction and visibility problems' experienced with the VW 2000, at Cd 0.18. It might be impossible to see out of. It's roofline is exactly the AST-1 profile.
3) The AVA Streamline Shape Cd 0.15 is the 1938 Sch'o'rwagen, by Ludwig Prandtl. Cd 0.186 @ full-scale, and like the Drop shape, it's already at full-length, so it also has 'issues'. Good outwards visibility.
4) The VW Blunt Body Cd 0.15 ( solid bordered image ) with a truncated tail is Cd 0.15. If elongated, it's extremely likely that the long-tailed variant would be at least Cd 0.14.
5) So I would allow for a Blunt Body long tail. Their contour is essentially the AST-II. Good outwards visibility.
6) The VW Flow Body, short-tail, Cd 0.15 is also essentially the AST-II.
7) Across the page from it, you'll find it's sibling, the Flow Body long-tail, Cd 0.14. Without wheels, Cd 0.0913. AST-II. Good outward visibility.
8) The other image is Wolfgang Klemperer's 'minivan' of 1922, Cd 0.16. It's also truncated, and could develop lower drag if elongated. Hucho developed his own half-body by fully extending Klemperer's roofline, for Cd 0.15. We do not have a plan-view image of Hucho's half-body.
I'm extremely 'visually' oriented. I don't have the facility to abstract forms as presented in Hucho's nested schematic. I need to really see them individually.
I'd be tickled to see any of these forms rolling down the road.
I chose what I chose because of the Flow-Body long-tail, leaning on the 2.5:1 streamline body's lowest measured drag, to dial-in as low a drag as I knew.
I like the wing cars too. I just don't know how an automaker could fare in the marketplace with them. Same goes for the ASTs as well. And that deserves it's own dedicated thread.

[JulianEdgar]

Originally Posted by AeroMcAeroFace

I think it is like a magic eye picture, you have to keep looking to eventually see it and only certain people can see it.

And, apparently, it's also like one of those images where you can see two quite different things.



Except in this case you can see five different things (or is it seven?). And if you can make changes, why isn't it infinite in number?

All so very strange.

[freebeard]

What I see is a static representation of instantiations of a form that could easily morph from one to the next using a slide control.

And the flow body is compromised, as aerohead points out, by the refractive index of glass. I don't know about safety glass but plate glass is 1.52, and IIRC lower is better. Ice for instance is 1.31, but not a suitable material for a windshield. Transparent aluminum is 1.78.

I still think the Beetle's small, flat windshield is a good compromise.