base drag visualization

[freebeard]

You'd have two very small 'canopies'.

The heads are less than 36" across so maybe a convergent nozzle in front, but the exit would be flush, below and to the rear of the axle, mostly ahead of the maximum width.

First thing out of the box modeler and into a new thread will be an electric rear-wheel drive version. The tires, motors and front suspension won't be on the market until next year, but i want to get that out there and then maybe look for a sponsor for the
VW powered version.

[aerohead]

There's a 28th image added up at the thread beginning.It looks like it's one of Hucho's wind tunnel scale models.Early Cadillac.

[freebeard]

What are the chances that color picture is of a die-cast model in a modern tunnel?

I haven't started that thread yet, but I shouldn't blame the software. Here's where it's at right now:



Bridgestone Tall/Narrow tires, Edison2 in-wheel suspension in front and Protean Energy in-wheel motors in back. They all should be on the market within a year.

[jeff88]

Aerohead, I'm wondering about the aerodynamics just ahead of the windshield on that Cadillac. If one were to put a sort of reverse kammback ahead of the windshield, would that eliminate the dip in the airflow helping improve the Cd? The arrow is the point that I'm talking about:



Obviously a real kammback/boattail would greatly improve Cd as well, but we all know about that!

[freebeard]

aerohead may have something to say next time he checks in, but meanwhile...

At the location you indicate, in that era, they would have used a deep V-shape. Later Tatra and others found a 3-piece windshield with narrow 'wind-wings' incorporated in the sides beneficial. Probably because a flat, vertical windshield is best optically, and safety trumps aerodynamics. Eventually you get the late-50s GM Wraparound windshield that had a lot of distortion.

Actually, an aerodynamic fore-roof truncated to a flat plate sounds a lot like my VW Beetle.

[aerohead]

Originally Posted by freebeard

What are the chances that color picture is of a die-cast model in a modern tunnel?

I haven't started that thread yet, but I shouldn't blame the software. Here's where it's at right now:



Bridgestone Tall/Narrow tires, Edison2 in-wheel suspension in front and Protean Energy in-wheel motors in back. They all should be on the market within a year.

I believe that they're all 1:18-scale die-cast models.And I didn't track down the source,but I'd bet the photo is from Wolf Hucho's personal scale wind tunnel.
If you GOGGLE him,a site will come up with other images.There's a thread I did on him a ways back.

[aerohead]

Originally Posted by jeff88

Aerohead, I'm wondering about the aerodynamics just ahead of the windshield on that Cadillac. If one were to put a sort of reverse kammback ahead of the windshield, would that eliminate the dip in the airflow helping improve the Cd? The arrow is the point that I'm talking about:



Obviously a real kammback/boattail would greatly improve Cd as well, but we all know about that!

*The majordomos would say,round off the leading edge of the radiator shell first to get the air attached onto the hood.
*Kamm would site a cooling system extractor at the cowl to help energize the flow over the screen.(you'd lose your ventilation air though)
*The upright windshield is causing a Prandtl Line of Discontinuity,the air avoiding the extreme acceleration around the hard edge by deforming the streamlines into a virtual radius.If 'hard-styling' mandated the upright design you'd be stuck with it.Otherwise you'd soften the header and A-Pillars leading edges to get attached flow.(In one thread there's a photo taken inside the A2 Wind tunnel where you see this effect on a 1930s High Boy Bonneville car.The radius is just enough to guarantee attached flow)
In Hucho's books he illustrates just how little radius is required.(the caveat is that larger radii help in crosswind/yawed flow,with the 'Bug' aerodynamic nose( see Schl'o'r wagen of 1939)being ideal for sub-transonic speeds).

[euromodder]

Hucho's site is Aerodynamik mit Wolf-Heinrich Hucho

And his wind tunnel :
http://aerowolf.com/wind_on_rauchkanal.htm