beetle and aero

[FJCamper]

Gentlemen,

A humbling experience is when, after all your aero tricks, that you discover you can actually go faster backwards than forwards.

A lot of people have discovered this at the last turn at Road Atlanta coming under the flag stand.

FJC

[yodogg]

Like this?

http://www.youtube.com/watch?v=ECo60jFq ... re=related

[4agedub]

I've been browsing the web for ideas on a rear wing... now I see most wings have Gurney flaps at the rear in order to reduce drag. This seems limilar to the old kamei rear wing spoilers.

http://i203.photobucket.com/albums/aa31 ... G_9215.jpg

Has anyone experimented with the position of such a wing on the bug's roof? Obviously you need to get it in the right position to be most effective.

http://i203.photobucket.com/albums/aa31 ... G_9236.jpg

Now here's some interesting info regarding lift and drag...
http://www.scielo.org.ar/scielo.php?scr ... 8000300001

[FJCamper]

Hi 4AgeDub,

The addition to the wing is a Kamm-style spoiler lip. The wing itself in the photo is itself a spoiler that reduces drag but does not exert downforce.

A "Kamm tail" is flat, as if the rear of the body were cut off, and the lip deflects air upwards to (partially) break the vacuum drag that is created behind the vehicle.

You've seen the electric factory VW and Audi roof spoilers that pop up just above the top of the rear window. Those are small in size but very efficient. Audi TT's were in fact crashing in Europe because of poor high speed aerodynamics, and the roof spoiler fixed that.

They were kept folded and automatically deployed after some (I forget the specific number) low road speed was exceeded to reduce drag and keep gas mileage up. Porsche and Chrysler also used electric spoilers, but not roof mounted.

This whole "wing-thing" started with a Porsche 550 Spyder. Here it is:

28-29 April 1956; 23rd Mille Miglia. Rain and a Winged Spyder. In the 1956 Mille Miglia in Brescia, Italy, the new factory-sponsored Porsche 550A Spyder competes, but the race is noteworthy for the first wing used on a race car. Swiss engineer Michael May devised a wing mounted just above and behind the driver in his privately entered 550 Spyder. He was ahead of his time. While running in practice in the rain, May passed the best drivers in the fastest cars, and recorded a 4th fastest qualifying time. This was faster than both of the two factory-entered 550A Spyders.

The Porsche factory-racing manager complained and had the wing disqualified. It would be 10 years before wings would reappear on race cars. In the Mille Miglia, it rains heavily, and Eugene Castellotti won 1st overall in a Ferrari 290MM Scaglietti. Porsche's best finish was 18th overall (but 1/2/3 in 1600cc Touring/GT class) with 356 Carreras. The best-finishing Spyder was 87th overall, and 3rd in 1500cc class. Dead last was a FIAT 1100cc for position 182.

FJC

[helowrench]

I still want to take the TT spoiler and graft it into a Ghia decklid

[yodogg]

Hi Helowrench,

Which one, the little ducktail or the elevated wing?

Also, Grassroots Motorsports had a great dos and donts of aero mods back in May 2010. Unfortunately, it is not available on their website, but they do sell back issues if anyone wants to check it out.

[helowrench]

Hi Helowrench,

Which one, the little ducktail or the elevated wing?

Also, Grassroots Motorsports had a great dos and donts of aero mods back in May 2010. Unfortunately, it is not available on their website, but they do sell back issues if anyone wants to check it out.

In my dreams it is the little ducktail that raises automatically.

[yodogg]

Another consideration for reducing unwanted air flowing under the body (to augment the benefit of a front air dam) is fit "ground effects" panels to or in place of the running boards. This blocks further turbulent air from entering from the sides and behind the front wheels. Again, this can be done without big $$, just 18-20g sheetmetal, a heavy hammer, some c clamps and a long straight edge (a 2x4) will do. You can use the bolt holes for the running boards for attachment.

[ProctorSilex]

FJC,
What are the little ears to either side of the deck lid?

Thanks

BTW, I am hot for some Ghia aero!

[FJCamper]

Hi ProctorSilex,

Those are small air scoops for the carburetors.

There is a flex tube under the scoops that goes to the firewall, then to the carbs. Here's a view of the engine side with tubes in place.



FJC

[brenmobile]

I want to improve the aero of my '64 drag bug. Some of us here in Michigan are working on building bugs with close to stock drive-trains for drag racing. We all have different angles we are going to try to make these cars faster without dumping lots of money into the tranny/engine set-up. I am interested in aero. My father was a clay modeler at GM. Were he still alive I am sure he would be helping me find ways to do this. So, I want to do this in his memory.

So, I am wondering about airflow around and through the front of the car. I and not going to run a stock gas tank. So, air will be able to flow through the front wheel well into the front trunk area. Is this going to be bad for aerodynamics? Seems like it would to me but I don't know.

[FJCamper]

Hi Brenmobile,

These photos may give you some ideas. And, no kidding, consider front and rear fender skirts. The fronts have to be bulged a little to accommodate steering.

FJC

[brenmobile]

FJC:
Thanks. Any ideas on how to mount a front airdam on a car with no bumpers or brackets? We filled all those holes.
Do you have any design recommendations for the rear roof spoiler?

-Bren

[FJCamper]

Hi Brenmobile,

With no bumper brackets, you'd have to be willing to attach a front airdam (not a spoiler -- spoilers break up or disrupt airflow, aidams dam it like water ... and I know everyone calls them spoilers) to the body with Dzus fasteners for removability, or screws or pop rivets if permanent.

The forward lower edge of a Bug is very well suited to a single piece of plastic or sheet metal, keeping it just below the hood line. The dam in this case slants with the body (slightly forward), not level, but it works, keeping air from under the car. It also adds front downforce.

The shape of the roof spoiler (it is a spoiler) is almost anything that stands up about two to three inches just above the top of the rear window and diverts air upward. This is what VW did on the New Beetle Turbos.

They made their spoiler retractable, as it is drag right up to the moment it becomes an aerodynamic necessity, which is about 80mph.

FJC

[brenmobile]

Wow, rear wing does nothing until 80mph? I won't need that anytime soon. At what point does the front air dam kick in?