beetle and aero

[Steve Arndt]

Why don't you drive with a camera and yarn, and test it out?

[ToRy 70]

Gerrelt did some wool-tuft testing!

http://www.gerrelt.nl/section-aerodynam ... ml?start=1

In the next page you can see the flow without the spoiler is attached.
I will definitely test mine in the same way.

[pickstock]

WHOA leave for a while with a half finished thread come back to somthing like this wow....

What do you guys think about angle? Mine is almost parallel to the ground but I see that Gerrelt's have a much more relaxed angle, which it seems that he did to decrease the chance of drag. It's funny, when viewed directly from behind mine is almost invisible. I wonder what the best angle is for vacuum breakup vs. drag.

The angle of my spoiler is about 12 degrees. I was told by a guy who was into gliders (the planes without engines), that everything over 12 degrees becomes an obstruction instead of guider.

On a race car, this kind of spoiler not only looks good, but I think will work very good too:












Probably easy to create too.. but it is not as subtle as my spoiler of course... [/quote]

from my understanding these are good for lowering drag rather than downforce, they look much like the KAMMBACK which i think is a hypermilling term, basically the two big mods to lower drag when hypermiling a car is the boat tail
http://www.google.com.au/imgres?q=boat+ ... uBQ&zoom=1

or for the less so inclined, the KAMM BACK
http://www.google.com.au/imgres?q=kamm+ ... =119&ty=31



IMAGE FAIL!

[Gerrelt]

WHOA leave for a while with a half finished thread come back to somthing like this wow....

What do you guys think about angle? Mine is almost parallel to the ground but I see that Gerrelt's have a much more relaxed angle, which it seems that he did to decrease the chance of drag. It's funny, when viewed directly from behind mine is almost invisible. I wonder what the best angle is for vacuum breakup vs. drag.

The angle of my spoiler is about 12 degrees. I was told by a guy who was into gliders (the planes without engines), that everything over 12 degrees becomes an obstruction instead of guider.

On a race car, this kind of spoiler not only looks good, but I think will work very good too:


http://www.gerrelt.nl/roofspoiler/1303_holzapfel.jpg

http://i43.servimg.com/u/f43/13/63/67/24/img_3615.jpg

http://i43.servimg.com/u/f43/13/63/67/24/img_2317.jpg

http://i43.servimg.com/u/f43/13/63/67/24/img_2416.jpg

http://i43.servimg.com/u/f43/13/63/67/24/img_2319.jpg

Probably easy to create too.. but it is not as subtle as my spoiler of course...

from my understanding these are good for lowering drag rather than downforce, they look much like the KAMMBACK which i think is a hypermilling term, basically the two big mods to lower drag when hypermiling a car is the boat tail

Yes, I totally agree with you. It does not create downforce, BUT, theoretically these spoilers reduce lift too. Which is almost like generating downforce, but then without the extra drag.

[pickstock]

i wont quote it because that would just get confusing...... haha

if your theories right then good on it, but from a speed point of view thats the way to go.

[shubea]

Hello guys dont mean to disrespect the Thread or the thread starter but this is the only topic I cound find about aerodynamics that is still active.. I just have a quick question..
Ive been lurking the forums for quite a while already. I have read tons of comments, ideas and knowledge regarding aerodynamics in vw. As many may have confirmed it already they say that aerodynamics for a VW beetle does not kick in till like your prolly running at 80mph - 100mph (correct me if im wrong). Anyways I have a 1974 1500cc beetle (brazil) and the fastest that I have gone so far no matter how hard I throttle was 74mph and the max speed in my speedometer is 86mph. So my question is If I made a few modifications to my bug in the aerodynamics side (Herod Helper or the equivalent, front spoilers and grill opening on my 4 fenders etc...) will It be able to aid me to attain a higher speed and not just get stuck at 74mph? by the way the back part of my bug has a little opening at the engine like this:



I also would want to know if that "opening" will increase drag or assist in reducing drag?

THanks so much...

[Wally]

I just made some aero mods on my car which I thought were fitting in this thread to complete the sum-up:



Some hot air escape vents above the header:


and the new A-pillar raingutter deflector from Gerrelt :

[Gerrelt]

I just found this interesting youtube vid & facebook item and thought I had to share it here.

See: http://youtu.be/IsDUVXscCGg

And there was a poll on the face book page, see the top red box. The answer is in the bottom red box:


(click on this get to the entire facebook page, I couldn't link directly to this item)

The beetle has 6% less drag when going backward.
I think it's because of attached flow staying attached to the rear window, which creates drag. Going backwards, there's nothing to attach to after the windscreen point. So the airflow can form itself like a teardrop.

(yes, shameless double post from the germanlook.net aerodynamics thread... sorry, but I had to put this here too)

[Bruce2]

and the new A-pillar raingutter deflector from Gerrelt :

Wally, what's the effect on wind noise with this?

[Wally]

What wind noise?

Tbh, I wanted it more for the reduced air resistance (higher top speed) and I think it works VERY well for that (too).

I am working with Gerrelt to create the large roof extension seen on some of the Cup cars like Thomas' to increase stability at top speed even more.

[Bruce2]

So I guess you're already deaf.

This originates from the Porsche world. The ones for 911s reduce drag, and reduce wind noise.

Do they make them for 1300 Beetles?

[Wally]

Nah, I meant they work so well, I don't hear any wind noise anymore

AFAIK, Gerrelt only made a version for the curved windshield, but maybe he can be pursuated if demand would justify cutting up an A-pillar from a flat windscreen beetle to make a new mould..

[4agedub]

We did some testing this weekend with wool. Yes it is a primative way of checking aero, but I do not have access to a wind tunnel

The first run was without the roof tab.

without tab on roof.jpg

The second with a tab on the roof to try and reduce the drag\

with tab on roof.jpg

For interest the front fender and door

door.jpg

Now, I am no expert in aero, but what I did see was that the tab did deflect air from the rear windscreen. The first run the wool stayed flat onto the windsreen torwards the bootlid. The second run the wool went torwards the tab.

Any comments??

The data logger did not give much evidence that it is working.

[Bruce2]

Nah, I meant they work so well, I don't hear any wind noise anymore .

That's what I wanted to hear!
How is it held in place? It looks like it wraps around the drip rail, then the window rubber holds the other side.
Or is there glue involved?

[Wally]

How is it held in place? It looks like it wraps around the drip rail, then the window rubber holds the other side.

Yes, ^^ thats the main attachment, but top and bottom also have a very slight recess with a double sided tape piece to finish the job.
Very subtle.