Roof spoiler effectiveness

[Chris Percival]

I run this wing, and from track experience, it makes a big difference to stability from speads as low as 60mph...


http://www.aircooled.net/new-bin/vie...RW0002&cartid=

[Turbo Haraune2]

Originally Posted by Eatoniashoprat

Holy , is your car really light or something? That speeds seems pretty slow compared to many others experiences with hi-perf suspension

My car isnt specially light. about 900kg ready to go.
But the whale tail is a big wing and make a big difference to aerodynamics.

and as we all know the beetle isn't very good aerodynamic from original design.

[Trogdor]

Talking about aerodynamics without wind tunnel testing is the same as talking about horsepower and never going near a dyno.

Some good reading.

Click

Click

Reading that and then going there are the only ways you'll know if anything you do is worth it. Otherwise you could be making things worse than they already are. And lets face it, is a Type4 powered Beetle ever going to handle or have a top speed warranting any sort of aerodynamic change?

[Cohibra45]

Trogdor,

Take a look here under 'Feature Articles' for a reprint of 'Käfer-Cup Beetle vs Porsche Carrera RS' from Sept. 95 VW Trends magazine...

http://www.germanlook.com/Html/Main.php#

I think it just might open your eyes to the quickness/speed that the 'lowly VW' can actually accomplish...


Take care,

Kelly (Cohibra45)

[Eatoniashoprat]

Originally Posted by Trogdor

Talking about aerodynamics without wind tunnel testing is the same as talking about horsepower and never going near a dyno.

Some good reading.

Click

Click

Agreed, however laptimes don't lie and you can't negate experienced driver feedback(I'm not in this group). For myself, I have a mechanical engineering degree and have studied a lot of the science behind it, but I can't attest to what is most effective on the track.

And lets face it, is a Type4 powered Beetle ever going to handle or have a top speed warranting any sort of aerodynamic change?

Yes?

[Bullyboy]

If anyone has driven a super beetle in 80-100kmh wind without a kamei front spoiler and then bolted one on.........nuff said.
The wife fought the idea of a spoiler until we took our first trip on the highway with it. Huge difference even with cross winds and semi's passing.

[Steve C]

Originally Posted by Bullyboy

If anyone has driven a super beetle in 80-100kmh wind without a kamei front spoiler and then bolted one on.........nuff said.
The wife fought the idea of a spoiler until we took our first trip on the highway with it. Huge difference even with cross winds and semi's passing.

Hi

I agree, I recently fitted one to my daily 1303, now I only hear the wind and don't feel it.

Steve

[Wally]

I agree with the above remarks about spoilers.
Front air dam made a huge difference. I have an original NOS Kamai one fitted now. A rear roof lip would work some I think. Anything that breaks the air wanting to follow the wing-liked shap of a rear beetle end, will work. I use a acn street-style rear wing for this:

[beetle1303]

One thing to consider IMO is how much the added spoiler/wing will affect the amount of air going into the slotted area under the rear window. For example the wing in the pic posted by Chris Percival will reduce the amount of air going into the engine bay... and this is the cooling air for your engine.

I seriously believe that a combination of a roof lip and wing of suitable size and position will provide the best results while keeping airflow into the engine bay at a respectable volume. On the other hand you could use a wing like Chris Percival and find another way of allowing air into your engine bay. one way to do it is from the underside if you want to keep the original look of your bug. this though dictates the use of some kind of belly pan.

Ive been thinking about this for my 1303 for a while now trying to find mounting positions and different mounting mediums to avoid drilling the pan halves. if you start going this way it would be worth it to try NOT to make the belly pan flat. in addition you can prepare it for some sort of diffuser at a later stage.


Another thing to consider is the air spilage aroung the back surface of the fenders. only if you are looking to sqeeze everything out of aerodynamics aids. Unfortunately the rounded shape of uor fenders if pure eye candy, but they kind of suck in aerodynamic respect. I would be wise to open holes on the back of the fenders to allow escape routes for the air coming in from under the car. Air is NOT coming into the fender well area through the wheel. also place some kind of winglets not to allow the air coming from the top to merge with the air coming from the side. I need to investigate further on this to justify, but its an idea...
Chris

[Wally]

Chris,
The wing Chris Percival posted was the old version. Mine has quite a nice large gap between wing and body just to overcome the point you mentioned.
I run it and have head (4 of them) and oil temp sensors and none showed any difference...

Walter

[Wally]

Chris,
The wing Chris Percival posted was the old version. Mine has quite a nice large gap between wing and body just to overcome the point you mentioned.
I run it and have head (4 of them) and oil temp sensors and none showed any difference...

I do believe the lip works as it disrupts airflow and therefore reduces lift. The difference is (I think) that the wing style will probably give some extra downforce to boot

Walter

[Eatoniashoprat]

Originally Posted by Wally

I do believe the lip works as it disrupts airflow and therefore reduces lift. The difference is (I think) that the wing style will probably give some extra downforce to boot

Walter

You're right with that, the lip only reduces lift, and the wing provides downforce.

One can see how the wing produces downforce, but how the lip works is less intuitive (I think anyway). The lip acts as a sort of vortex generator to make the boundary layer (air flowing very close to the car surface) more turbulent. Turbulent boundary layers stay attached to the surface longer than laminar ones. This is why vortex generators are sometimes added to fighter jets, in order to increase the stall angle if the wings are designed poorly and the flow would normally seperate off the wing prematurely. Where the boundary layer is 'attached' (not seperated) it provides a pressure on the surface, so you can see that if the boundary layer seperates early this pressure is reduced and the car will start to lift. Make any sense? I'm not sure if the explanation was needed (or clear) but I just felt like explaining, for interests sake if anyone was interested.

[Wally]

Very interesting to say the least!
Maybe an avionics engineer or student could chime for this aspect of aerodynamics?

[Chris Percival]

I don't think a lip spoiler is that clever in our application. They just detach the laminar flow from the rear of the car, thereby eliminating any lift that flow might be generating, nothing more..

[Turbo Haraune2]

Well I am a helicopter engineer, and I say you cannot use them in a combination.
Just as individual spoilers, because the roof spoiler wil destroy the airflow to the tail, and you loose all effect of it.

My opinion based on experience is that the Tail spoiler gives you most downforce and makes the car more stable. bigger=better!!