Wings/aerofoils Are they really needed? and if so when?

[BeetleBug]

Here is some more slightly related info (new beetle)
http://www.autospeed.com/A_108675/cms/article.html

Brilliant picture and info Trond, thanks for sharing.

So this proves it, unless you mount your wing above the rear window and/or make it very long you can just as well forget about the downforce effect. What you cant see in the picture is that the wind is actually going upwards further down towards the rear lid. This explains why you see a lower engine temp when lifting the bottom end of the lid instead of mounting a so called "cool air". The cool air kit will allow heat out of the engine bay but lifting it up at the low side will allow more air into the bay. But only as much air as you can get out.

-BB-

[Martin]

can anyone remember how fast the Stahl land speed beetle goes?

Looking at the great wind tunnal picture, looks like an effective wing is going to have to go above the rear window, or under the rear window but about 2M long! lol
it would be interesting seeing it with its nose down....but saying that, my cars front end is still high at the top end of the track.


link might work, if not give it a google
http://blu.stb.s-msn.com/i/FD/135EADC1632ED3AEB9D8B51CD8249

[tikimadness]

Thanks guys the posts from the last few days made it all clearer to me.
My car is in the workshop at the moment and talked to Jim about this subject. I wondered if he could make one. All I have to do is give him an example but I don't think google will come up with a picture of a wing fitted above the rear window.

Michael

[stretch]

Thanks guys the posts from the last few days made it all clearer to me.
My car is in the workshop at the moment and talked to Jim about this subject. I wondered if he could make one. All I have to do is give him an example but I don't think google will come up with a picture of a wing fitted above the rear window.

Michael

Michael, be careful, if you mount the rear wing above the rear window it may cause people physical harm to their eyes, or induce vomiting.  I personally really like it, but, hey thats just me.   

Anyway, looks like the wing may have been in the 'correct' position, whether it's aesthetically pleasing or not.   

Hope the pic helps.

[Trond Dahl]

That guy  has been in a wind tunnel for sure

[BeetleBug]

Thinking about it: A small, plastic wing mounted on the upper window rubber can make all the difference in the world on our cars. It will create less drag and create down force. It should be easy to make too. If I remember correctly the wind starts loosing it's "grip" at angles around 25-30 degrees.

Hmmmmmm...

[Fastbrit]

My car in 1992...

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[Airspeed]

I do remember a wing like that on Martin's split some years ago while it was visiting Spa-francorchamp (Lebug show)  
It didn't look that out of place compared to those ugly(er) dragcar 'geisha' extensions (back packs)  
I ran an (also ugly looking) small rear wing halfway of the rear window for a trackday, but couldn''t really tell a difference with or without it. Did give me more confidence though...

You can just spot it there:

[Jon]

There are a lot of talk about downforce in this thread, and I ask myself, is that whats needed?  The problem as I read it in this thread is that the body shape produces lift? Isn't it enough just to get rid of the lift?

That being said, maybe thats exactly what people have been achiving with the wings in the normal low position on the bugs? I mean, when I look at the Volvo PV video I can't see any evidence that the wingplane is seeing any force from the wind, it's hardly bending at all, and you can see from the vibration that this wing is pretty thin. I bet it would bend more from placing a bag of groceries on it.
But here comes the twist, these wings still work... But they are not producing actual downforce... Maybe they change the profile enough to eliminate the lift. Maybe they create a pillow of turbulence ontop of the wing... So the airflow  rides over that....  

Ofcourse, you can keep a airplane on the ground by adding spoilers creating downforce, just seems much smarter to take the wings off.

Just some thoughts on the subject.

[Berger]

There are a lot of talk about downforce in this thread, and I ask myself, is that whats needed?  The problem as I read it in this thread is that the body shape produces lift? Isn't it enough just to get rid of the lift?

That being said, maybe thats exactly what people have been achiving with the wings in the normal low position on the bugs? I mean, when I look at the Volvo PV video I can't see any evidence that the wingplane is seeing any force from the wind, it's hardly bending at all, and you can see from the vibration that this wing is pretty thin. I bet it would bend more from placing a bag of groceries on it.
But here comes the twist, these wings still work... But they are not producing actual downforce... Maybe they change the profile enough to eliminate the lift. Maybe they create a pillow of turbulence ontop of the wing... So the airflow  rides over that....   

Ofcours,e you can keep a airplane on the ground by adding spoilers creating downforce, just seems much smarter to take the wings off.

Just some thoughts on the subject.

So you are saying we should take the roof of....? 

[Jon]

Yes, or make a little sharp wedge shaped spoiler on the rear part of the roof, to get the air to break free... I can't remember where I got it from, but I saw it described somewhere.

[richie]

So you are saying we should take the roof of....? 

Nooooo,I dont want to see the pits full of roofless cars,they look sh#te


Keep it coming everyone,lots of things to think about and the more input the better,that pic Trond posted really shows how little effect the conventional wing has,now if we could just get the same thing[picture] with a front splitter on it to see what happens as a comparison it would be perfect


And the report of the new beetle makes me even surer that most wings on beetles are pointless for downforce


cheers richie

[Fastbrit]

But they make a cool place to rest a cup of tea...

[Berger]

So you are saying we should take the roof of....? 

Nooooo,I dont want to see the pits full of roofless cars,they look sh#te


Keep it coming everyone,lots of things to think about and the more input the better,that pic Trond posted really shows how little effect the conventional wing has,now if we could just get the same thing[picture] with a front splitter on it to see what happens as a comparison it would be perfect


And the report of the new beetle makes me even surer that most wings on beetles are pointless for downforce


cheers richie

Pjuh, that's a relief, now I can skip making a wing for my racecar, and make a invisible splitter instead

[Frallan]

This is what I am getting inspired from and my Beetle will get the wing for sure this summer.
A CF wing has waited for two years. Stream lined profile struts and support arms in to the roof.
High enough but just not too extreme.

Fun Cup website. Nope, not aircooled but looks good. Everything can be bought from a pricelist. Every single component. Not cheap though.

http://www.funcup.co.uk/default.asp

[Martin]

But they make a cool place to rest( a cup of tea...) Beer.

corrected it for you Keith

[Fasterbrit]

My understanding of a Beetle's aerodynamics is to disrupt the airflow at the rear to stop the car's natural tendency to lift the rear at speed. Excessive downforce at the rear should be avoided because the moment you create downforce at the rear the front will rise makIng it go unstable.

My own experience with my car led me to create a wing that sat beneath the rear window to disrupt flow. Now I don't have any fancy data loggers, so I can't baffle you with numbers and science. But I have a 'butt-o-meter' which registered that prior to the wing the car was undrivable above 135 mph - the rear was steering all over the place the moment I backed off or pulled the 'chute. It was downright dangerous. Since I fitted the wing - and made no other changes! - the car has driven arrow straight at speed. 146 mph feels so stable I don't even bother with the 'chute. Now I am not suggesting I have invented the wheel or anything; simply conveying my experience on my car, which will be setup differently to every other car.

My advice to others would be don't dismiss the simple rear wing beneath the window as it works in certain applications. Try it and see for yourselves.

[Jyrki]

There are a lot of talk about downforce in this thread, and I ask myself, is that whats needed?  The problem as I read it in this thread is that the body shape produces lift? Isn't it enough just to get rid of the lift?

AND

My understanding of a Beetle's aerodynamics is to disrupt the airflow at the rear to stop the car's natural tendency to lift the rear at speed.

Gentlemen, I believe you have pointed out the essential!!!
Jyrki

[36hplandspeedracer]

Bob Stahls 65 Bug did a 155.828 mph in 2004 at Bonneville (see pic below):


Bobs large wing is essential to stabiilty in any VW Bug at speeds above 110 miles per hour! Photo by Burly Burlile.

Here is my two cents worth. Back in 91 and 92, my partner Kerry Hart and I built a stock bodied (no wing or aero!) Super Beetle to run on the Bonneville Salt Flats with a goal speed of 133 miles per hour. Kerry made it to 131.296 mph and I hit a high speed of 129 mph. I can personnally verify it was down right "scary" at those speeds with the rear end lifting and dancing around even with 500 lbs of ADDED ballast (200 front/300 rear) and another 200 lbs of added safety gear and dry oil sump system. Kerry later did three 360 degree spins on the salt at 115 mph because the car had no rear wing. The 700 plus pounds of added ballast and the lack of walls down Bonnevilles long black line meant he did not roll or hit anything with the SB. See pic below:


Burlile/Hart stock bodied Super Beetle in 1992. Photo by Dave Taylor.

Dean Lowry's last racing effort, another land speed racing Super Beetle was topping out around 130 mph at El Mirage before he added a simple old VW accessory called a Herrods Helper, an aluminum wing that clamps onto the air slots under the rear window. Once the HH was installed, the added stability allowed him to jump up to speeds in the low 140's. Unfortunately he passed away before realizing the full potential of his winged VW. Although Deans Super Beetle was esseentially stock bodied, the addition of the rear wing placed him in and altered land speed racing category: See pic below:


You can see the simple bolt-on Herrods Helper just behind Deans head in the photograph. Photographer unknown?

To date the fastest stock bodied Beetle in land speed racing belongs to the Hicks/Forlano 61 bug set in 1991 with a top speed of 132.100 miles per hour. See pic below:


A year after this photo (photographer unkown) was taken, they added a rear wing and their speed immediatley jumped up to 141.242 mph on the idrt at El Mirage.

I would strongly reccommend anyone expecting their Beetle to exceed 110 miles per hour in drag racing or land speed racing (or on the street!) to add a rear wing, even if it is something as simple as the new replica Herrods Helpers currently available. This aerodynamic improvement will greatly reduce the chance of aero related instability.

Burly  (36hp Challenge)

[Frallan]

Bob Stahls 65 Bug did a 155.828 mph in 2004 at Bonneville (see pic below):


 Photo by Burly Burlile.

I met Bob out on Muroc or whatever it is called north east 2 hours from LA.
One item he talked strongy about was the two small roof rails. They gave added stability.
They are visible in this picture.

Another one was the weight that you mention Burly. He showed what it looked like under the hood up front. Not like a drag race car, that is for sure. A LOT of lead.

[Basti]

hm...intresting thread..

I was working on some professional racecars in the windtunnel before.
All had some nice looking wings (Designed and calculated before) which most times didn´t work at the first time.
It was ALLWAYS a long day with a lot of meassurments to find a solution
which really helps the car.

The wing of the Fun cup car is in my opinion just for the show and
I think it will be faster without it...

just my 2 cent...

Cheers,
Basti

[BeetleBug]

It should be possible to make a small size cabinet, add a air compressor and some smoke and take it from there like this guy:

<a href="http://www.youtube.com/v/vsFwU4T_qe8" target="_blank">http://www.youtube.com/v/vsFwU4T_qe8</a>

Interestingly enough it is a cabriolet 

[richie]

It should be possible to make a small size cabinet, add a air compressor and some smoke and take it from there like this guy:

<a href="http://www.youtube.com/v/vsFwU4T_qe8" target="_blank">http://www.youtube.com/v/vsFwU4T_qe8</a>

Interestingly enough it is a cabriolet 

That is so simple,but so usefull,well to me anyway  
I would have never believed that putting the roof down would make so much difference,the way it follows the roof line rather than just get forced up in the air from the windscreen has got me really puzzled,why doesnt it hit the screen and go upwards when the roof is up like when the roof is down? I understand it will change the way the air moves,but not how drastically it does?
Anyone explain?

cheers richie

[Berger]

Yes, or make a little sharp wedge shaped spoiler on the rear part of the roof, to get the air to break free... I can't remember where I got it from, but I saw it described somewhere.

So we need to brake the wing effect the beetle has, by not letting the air go under the car, and not follow the back of the car down to the ground.
Easiest done this way ?

 

[BeetleBug]

Check this one out:

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Decrease in aerodynamic drag coefficient: minus 4 %
Increase in top speed: plus 2.3 %
Reduction of fuel consumption: minus 1.5 %
Decrease in lift coefficient on front axle : minus 64 %

Front axle lift at 125 kph / 80 mph is reduced from 2 cm to 0,5 cm.

There is quite a lot of interesting info to be found on the web, especially from people trying to reduce the drag to improve the fuel consumption (believe it or not). Roof wing:

http://www.gerrelt.nl/section-aerodynamics/roofspoiler-explanation.html

A little more on drag and performance:

http://www.autospeed.com/cms/A_3058/article.html

http://www.autospeed.com/cms/A_3059/article.html

http://www.autospeed.com/cms/A_3060/article.html

And the conclusion is really interesting:

http://www.autospeed.com/cms/A_3061/article.html

-BB-

[richie]

My car in 1992...

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Keith did you notice much difference with that wing as opposed to the more tradiational spoiler you had before?at what point was the front piece added?


cheers richie

[richie]

Bob Stahls 65 Bug did a 155.828 mph in 2004 at Bonneville (see pic below):


Bobs large wing is essential to stabiilty in any VW Bug at speeds above 110 miles per hour! Photo by Burly Burlile.

Here is my two cents worth. Back in 91 and 92, my partner Kerry Hart and I built a stock bodied (no wing or aero!) Super Beetle to run on the Bonneville Salt Flats with a goal speed of 133 miles per hour. Kerry made it to 131.296 mph and I hit a high speed of 129 mph. I can personnally verify it was down right "scary" at those speeds with the rear end lifting and dancing around even with 500 lbs of ADDED ballast (200 front/300 rear) and another 200 lbs of added safety gear and dry oil sump system. Kerry later did three 360 degree spins on the salt at 115 mph because the car had no rear wing. The 700 plus pounds of added ballast and the lack of walls down Bonnevilles long black line meant he did not roll or hit anything with the SB. See pic below:


Burlile/Hart stock bodied Super Beetle in 1992. Photo by Dave Taylor.

Dean Lowry's last racing effort, another land speed racing Super Beetle was topping out around 130 mph at El Mirage before he added a simple old VW accessory called a Herrods Helper, an aluminum wing that clamps onto the air slots under the rear window. Once the HH was installed, the added stability allowed him to jump up to speeds in the low 140's. Unfortunately he passed away before realizing the full potential of his winged VW. Although Deans Super Beetle was esseentially stock bodied, the addition of the rear wing placed him in and altered land speed racing category: See pic below:


You can see the simple bolt-on Herrods Helper just behind Deans head in the photograph. Photographer unknown?

To date the fastest stock bodied Beetle in land speed racing belongs to the Hicks/Forlano 61 bug set in 1991 with a top speed of 132.100 miles per hour. See pic below:


A year after this photo (photographer unkown) was taken, they added a rear wing and their speed immediatley jumped up to 141.242 mph on the idrt at El Mirage.

I would strongly reccommend anyone expecting their Beetle to exceed 110 miles per hour in drag racing or land speed racing (or on the street!) to add a rear wing, even if it is something as simple as the new replica Herrods Helpers currently available. This aerodynamic improvement will greatly reduce the chance of aero related instability.

Burly  (36hp Challenge)

I   wonder how different the Stahl car would behave without the scoop so high up,it must have a major effect up there,also those spill plates look like they will do some good.

cheers richie

[richie]

So having had a few days to digest all the info[and to much turkey ] I have started to make what I think a beetle needs,a front spoiler/splitter and spill plates for the back,I am not convinced by any rear spoiler that i have seen so far,so I will ignore that for now.
I have made a card template for the front,and will transfer this to alluminium this week hopefully time permitting,the spill plates will take more time as I havent got a clear idea in my head yet of size,shape and location.
I am doing this on a beetle saloon,not a cabrio 1st of all as the info should be more usefull to everyone,I have an idea I intend to use to fix the front splitter without any drilling or welding to the base car so as to make it totally removable in approx 10mins,if it works then I will share it,if it doesnt then I will keep quiet

cheers richie

[Fiatdude]

In my touring around the pits at a local VW race and talking to a couple of guys, I started looking at one of the cars that is quite fast in naturally aspriated form and the gentleman was running vortex generators on the roof of his car. I casually asked him about them and he said he was experimenting with them and didn't know if they helped or not. Well, knowing this gentleman and his legacy, I'd say that he doesn't do anything by chance and they were on there by design and the location was well thought out in advance.

These might be a solution to the problem without going to a wing.

<a href="http://www.youtube.com/v/We8LWkqjdX4" target="_blank">http://www.youtube.com/v/We8LWkqjdX4</a>

http://www.mitsubishi-motors.com/corporate/about_us/technology/review/e/pdf/2004/16E_03.pdf

[richie]

Anyway

Been watching some wind tunnel videos,heres a few I found interesting


<a href="http://www.youtube.com/v/8PoIoQNIoMQ" target="_blank">http://www.youtube.com/v/8PoIoQNIoMQ</a>

http://www.youtube.com/watch?NR=1&feature=fvwp&v=7Xc5TjtZh34

http://www.youtube.com/watch?NR=1&feature=endscreen&v=3EjFkPL_H_4


cheers richie