Aeromodability of a VW Bug?

[Frank Lee]

^That is the most plausible proposal yet although I think it can taper down faster.

[Sven7]

Yes, that's straight template right there. As we've seen lots of plan view taper can allow a larger taper in elevation, so that is a very conservative design. It could take a bit of testing to get right, though. Too bad we can't use that open source CFD...

[gtkid2002]

That last design could be doable with only cardboard and duct tape for testing purposes at least. I could try and test it on my '69, but I'll have to find some cardboard. Mom's moving out, and she's using all my online order boxes. Pity, because I ordered a tow hitch that came in a huuuge box.


I think this should have some sort of a door though. The concept of an open air thing would kind of kill the aerodynamics, although it could be fun. If I went with the inline two seater, I'd want a single gullwing that would open and allow access to both seats. I would really love to chop the chassis too, but the concept of a decent sealing door honestly makes me doubt that I can. Although I could swing a shaped plexi window thing I guess. Still would freak me out though.


Sven7 - Lowering it is something I'm torn on. I know it could improve FE, but if it's lowered, it might not have all the function as a bug used to. Granted that it's not really a bug anymore anyhow, but knowing that it could handle in snow would be nice. Although making that out of cardboard for testing at least could be interesting. I also was wondering, wasn't the front the ugly aerodynamic part? I think somebody suggested I get another rear hatch and weld it on the front earlier.


Oh gosh, would having a fully smooth bellypan make it a sled in snow? If that's the case, I want to make one that is removable. I live up 500 feet right now. Sledding down in my car would be BAD.


I'm gonna have to type up the full list of ideas I've been trying to think of while on lunch at work. Just minor things I'd like to incorporate into a final draft, like the 2 cylinder mod thing.

[kach22i]

Originally Posted by Sven7

Basically just cut the back off and custom build the rest... it could be a fiberglass clamshell if you don't want to beat panels :P

I tried my hand at a more complex alternate, using Tyler's drawing as a base.

To make the doors operational with the extra thickness, one would have to add a deep wedge or cut-out (not shown). The leading edge of the door would be similar to how they treat thick rubber door trim. This of course might disrupt the air flow, not sure of the net gain (if any).

On the other hand, Beetle doors are only a couple of inches thick, verses 6 inch thick modern doors, maybe redoing the hinge is all that is needed.

Automobile pictures by kach22i - Photobucket


Too complex?

[aerohead]

Originally Posted by kach22i

I tried my hand at a more complex alternate, using Tyler's drawing as a base.

To make the doors operational with the extra thickness, one would have to add a deep wedge or cut-out (not shown). The leading edge of the door would be similar to how they treat thick rubber door trim. This of course might disrupt the air flow, not sure of the net gain (if any).

On the other hand, Beetle doors are only a couple of inches thick, verses 6 inch thick modern doors, maybe redoing the hinge is all that is needed.

Automobile pictures by kach22i - Photobucket


Too complex?

If you'll do a Search EcoModder for 'Chrysler Airflow,' you can see what Carl Breer and his team did for the DeSoto Airflow test mule in 1934.
The aerodynamics of that car are very similar to the Beetle.

[Frank Lee]

Bug hinges are outside already; no redo necessary.

[Sven7]

Honestly with the fenders' couple inches of offset from the body, the wedges in the door trim would have to be enormous to clear when opened. You could attach some sort of rubber fairing to the rear of the front fender to cover the gap but it's honestly nearly unavoidable.

Maybe take some common volkwagen modification techniques and make it work for aero. Many people, when lowering their bugs, need to narrow the front axle to be able to turn the wheels inside the fenders without rubbing. Now, what if you narrowed the beam and also the fenders? If the car were not too low in ride height, and maybe had some lower profile tires, you could presumably decrease the frontal area by a couple square feet. Well, maybe not the total frontal area, because the rear fenders would still be there, but you get the idea. From plan view it would look more like a teardrop and less like a deformed frog.

The rear fender could be rebuilt with a tapering front, as this would not necessitate major body modifications.

[gtkid2002]

aerohead - I read that article. It does bear a really striking resemblance to the bug. Kind of ironic though. The Cd on that was .55, while the bug was .49? Yet it was supposed to be quite a bit more streamlined. I do find it amusing that it seems like they didn't come with any engine smaller than a 6 cylinder. Heaven forbid you have a straight four in it. Save some weight and boost your FE more. Seems like kind of a pity to me.

Sven7 - I think a rubber fairing wouldn't be too bad. I'd want it to overlap onto the door, so it would rub against it, but that way you wouldn't get close to interfering with the hinge. Anybody who's scrapped/thrashed a car knows how easily car doors can just be bent backwards. Doesn't even take much more than a forceful shove, and I did that to the car on my display picture. Granted that's different from a bug, but those were also quite thicker doors, and it had beefier hinges than the bug does. Heh, it sounds like an aeromodded bug would look a bit more like a streamlined hot dog more than anything else.

I'm also not sure if it's possible to get low profile tires to fit the stock rims or without a 4x100 lug/stud conversion plate and some Honda rims. Although finding smaller diameter low profile tires might be amusing to try.

Making that clamshell is getting tempting to try at least. I have a trailer hitch on my '69, so if I made it attachable to that, I could have it have its own lighting, powered by trailer lights. I still have to figure out how the crap to wire the brake lights and running lights in a 4 wire harness. Confusing me it is.

Also, after seeing the article on the Airflow, does anybody know if there would be issues on the legality of split front windows on modern cars? The concept of reusing the glass is something I'd like to do, and the idea of using the glass from the rear half of the bug on the front seems a bit better than the other way around. Although the quarter windows are flat. Ergh.

[Frank Lee]

Honestly with the fenders' couple inches of offset from the body, the wedges in the door trim would have to be enormous to clear when opened. You could attach some sort of rubber fairing to the rear of the front fender to cover the gap but it's honestly nearly unavoidable.

Are we talking about the same concept? Cuz look at ANY old 30s - 50s car; their doors opened and shut.



See any rubber fairings or gaps?

[Sven7]

Frank, those cars have completely different hinge mechanisms. The American car doors with C shaped hinge arms move out as they rotate, but Beetle hinges rotate the door literally using the hinge pin as the axis. If you have any 1:24 scale car models lying around they usually use the C arm type hinge. It allows a larger radius for the door to open on so it can clear the fabulous body forms we see on those cars.

The Beetle's simple external hinges just aren't made to have large fender forms on the doors. They're made to open the doors adequately and as cheaply as possible- after all, Porsche's people's car was about function, not form.

Also, gtkid, you might cruise the internet looking for 145/80/15 tires. I know these are commonly used for fronts on Beetles when they start rubbing normal width tires. You might even use them all around.

The main problem is rubbing the front tires against the inner fenders while turning. You could install skinny or low profile tires (skinny will be easier to find), narrow the beam, and/or even just live with the wider turning radius. My Probe's air dam scrapes every time I enter or leave the local CVS's parking lot... I deal with it. If the Beetle is to be mainly aerodynamic maybe you sacrifice a little low-speed maneuverability for some high-speed drag reduction.