Describing my Beetle wing (VW New Beetle)

[Ernie Rogers]

Originally Posted by trebuchet03

Ever since I saw your beetle... I've always wondered what the inspiration behind the winglet shape was.

Beautiful build though, I'm always a fan of quality

I think it was about 1978, I was sitting at the same table with Peter Lissaman of Aerovironment. I told a story I thought was funny about a school teacher that said we should put a wind turbine on a car. The faster the car went, the more power you get from the turbine, and that would power the car, we would never need gas again. I then commented that if there was a headwind, you could get more energy from the turbine than what you might need to power the car.

Lissaman, in a condescending tone, said he had published a paper on that 10 years before that showed you could power the car provided there was wind from any direction.

I took that lesson away with me, and realized that just a simple fin on a car had the potential to improve fuel economy by developing lift, provided that there was some available cross-wind.

When I was designing the wing, I had every intention of putting on tall fins, maybe about 3 feet tall. Family members pressured me to abandon that idea. We made a family project out of it, to design the winglets. And, what you see was accepted by all before the build was started.

My public response: Girls fall in love with my car. The Bull-Durham chewers out here laugh at it and call me unpleasant names.

Cars generate corner vortices similar to those on aircraft wings, and I suppose there may be some small benefit in suppressing them.

I still secretly intend to put on the three-foot fins some day.

Ernie Rogers

[Ernie Rogers]

Originally Posted by MetroMPG

This is really good detail - thanks for posting it, Ernie.

I'm with Trebuchet: looks like a quality build.

Thanks, guys, for the nice compliments.

The photos were taken before I screwed up the paint job last summer. It seems to work fine; I'll get around to re-painting one of these days.

Ernie

[ECONORAM]

Ernie, the winglets and spoiler make me wonder...will this work on my truck? I ask because I am a big fan of the old Daytonas, and they had a mighty big wing! Aero Warriors - Aero Warriors Images, Part 1 I can get one for my truck, but I do not know if anyone has tried mpg measurements with it...
The drive from SLC to Wendover is not too bad. My wife and I got 36.9 mpg with her 08 Avenger on that stretch earlier this year.
I am curious where you did some of your reading about the wind...

[aerohead]

Ernie,from Kelley and Holcombe's SAE paper of 1963,which established a relationship between drag and mpg,and using your baseline of 58-mpg at 60 mph.For 61 mpg,I get Cd 0.34 and at 65.5 mpg,I get Cd 0.28 for your New Beetle.
Off hand,I can't remember what the Herrod Helper did for the original Beetle back in the 1970s,but your wing is a massive improvement over that wing and it's been fun for years now,to know you've been out there getting these great numbers!
She looks like a production piece too,and probably garners a lot of attention from other VW owners.
Thanks for doing it and sharing the build info.It sets a great bar for the rest of us to work towards.

[JasonG]

Originally Posted by Ernie Rogers

Third picture shows a small gap between the leading edge of the wing and the car surface. The intended purpose of the gap is to suck out a separation bubble that could form there.

Hmmm, haven't thought of that before.
Any chance of doing a masking tape A-B-A test of the gap. Makes sense, sort of like a diffuser.

[Ernie Rogers]

Originally Posted by JasonG

Hmmm, haven't thought of that before.
Any chance of doing a masking tape A-B-A test of the gap. Makes sense, sort of like a diffuser.

Hello, Jason,

That is a very good idea. No tests of that sort have been done by me. I will try it some time this summer. Or, any students out there looking for a research project? I think this has some possibilities for wind tunnel testing.

Ernie Rogers

[Ziyad]

Great work!! That mod should, and did make a marked improvement!

[elhigh]

Originally Posted by aerohead

Off hand,I can't remember what the Herrod Helper did for the original Beetle back in the 1970s,but your wing is a massive improvement over that wing and it's been fun for years now,to know you've been out there getting these great numbers!

I recognized that name, "Herrod Helper." I'm a sometime reader of Hot VWs and they had an on-again, off-again article series called Project Mileage Motor. They did a lot of the stuff we do, optimizing the chassis and whatnot. They started with a crusty 72 Super Beetle, which whistled up a merely fair 20mpg as bought. Chassis tuning, bearing greasing, etc brought that up to 28.

Adding their engine brought mileage into the middle 30s with some engine tuning and trying various options. It's all written down, anyone with an aircooled Beetle and a full set of wrenches can roll their own.

The Herrod Helper added 2mpg. This was after they'd already achieved a solid mid-30s score; nobody was expecting another 2mpg with this little wing. Last I saw, the Mileage Motor Beetle had managed about 38mpg at California freeway speeds, a really good result. It seems the magazine has lost interest, though - every new issue that comes out, I scan for an update. Nothing.

[bnmorgan]

Very interesting looking....but who cares how it looks if it helps. Any idea if there are benefits to the "stock" spoilers? I know the Turbo-S 1.8 turbo gas cars have electric auto-spoilers at the top of the rear hatch....I wonder if that helps?

[ECONORAM]

It depends upon whose stock spoiler. The Dodge RAM SRT-10 is a good example of a factory vehicle that uses a rear spoiler to cut drag. It is only part of the RAM SRT-10's lower Cd as compared to a truck like mine. See Viper powered 2004 Dodge Ram SRT-10 Scroll down to the production version text in the blue box.