333pg333

I'm pretty sure I've seen cars with small 'lips' on the rear of the boot that also run big wings. Can't do the searching, at work, but if Mr McBeath says it's ok to run the small one in the pic above I'll give it a go.
I think our stock rubber rain catcher might not be the best idea though.

JustinL

Duke

As far as I know a spoiler doesn't disrupt air flow.. As you can see the air is extremely turbulent at the end of the trunk, that turbulence would start later with a stock spoiler in place.

There is a reason why double element wings are very powerful. Here's a good animation:

Duke

That reason is most likely "regulations".

67King

I know the RS500 version of the Cosworth used both a big wing and a small lip spoiler on teh trunk. The street version only had a wing.

reno808

those were the ones with the double wing right?

67King

The American Sierra based Merkur XR4Ti had a double wing. But the Cosworths had a very large single wing. The RS500's, which were built for homologation, had a big lip on the wing, and a smaller lip on the hatch. They were usually painted flat black.

SirLapsalot

That's what I thought too then I started to read the regulations and gave up because I should be doing other things right now but if anyone wants to read the regulations here they are:

http://www.imsaracing.net/2011/alms/...%20Quality.pdf

Random but as and engineering student I thought this part was cool to know:
2.5 - Material
The use of a metallic material which has a specific yield modulus greater than 40 GPa/g/cm3 is forbidden.
The use of magnesium sheet less than 3 mm thick is forbidden.
The use of parts made from titanium is authorised, but welding is forbidden for parts of the suspension, steering or braking systems.

Duke

I took out the book "Competition Car Aerodynamics" from the bookshelf and tried to find something useful.
There was a wind tunnel study of the IMSA GTP Jaguar XJR-16 and the effect of the lower rear wing flap angle. Downforce increased with more angle (and naturally also increased drag). They tested 25-35 degrees on the lower wing which is very aggressive compared to the 951 spoiler. I cannot find any information about a lower wing or spoiler disturbing the upper wing.

TonyG

We are not talking about double element wings. We are talking about using the 951 rear spoiler in conjunction with a wing.

A wing on top of another wing is either two wings, or if close together is simply a double element wing. In either case, the shape of them don't affect the other negatively.

The 944 "wing" is not a wing. The shape is not even remotely close to that of a wing. The shape of it does disrupt the air flow (by design, and just like that of what was used.... albeit much larger, on '80's 911 turbos). Thus using it in close proximity to a real wing is a bad idea.

And this is what was told to me by Dewain at Vision Motorsports (the person that built my wing). Also the person that built Orca and Shamoo. The same person that did a lot of wind tunnel testing back in the '80's on 944's.

That's where I got my information. And it makes sense.

If you're gonna bolt anything to the hatch with a big wing, it should be something like the 968 hatch trim.

I don't run anything on my hatch and the down force the wing provides, even run almost flat, provides enough down force to stick the back of the car at anything over 125mph with corded tires. I'm trying to take out down force at this point... not add to it.

Furthermore... if you are going to put a big wing on your car, do it through the lexan hatch straight down to the "frame rails". It's got the proper structural strength with the loads being applied in the proper location, the wing supports are close enough together that the wing won't flex (which is definitely not good), and it's easy to remove (4 bolts).

TonyG

TonyG

A wing with a flap... is a wing with a flap. A flap on a wing is an extension of the wing and effectively increases the camber of the wing as a whole.

And it's a much different shape (aerodynamically, no matter the flap angle...) than the shape of the 951 rear spoiler.

The 951 rear spoiler isn't a wing to begin with.


TonyG

Dubai944

I'll be removing the rubber spoiler when I fit my wing. It's quite a heavy chunk for what is is and, Aerodynamic or not, I think it just looks a bit ricer racer with both



Continueing on topic of 2012 plans I will also be fitting the remote filler kit to my fuel cell which at the moment I have to fill in the back of the car. That will be too awkward once the wing is in place even if it is only a couple of bolts to remove.

333pg333

^^Looks like Guns' old car^^

TonyG

Agreed!

Have always loved the looks.

TonyG

Duke

You might very well be right Tony, we're all just guessing here.
Yes 944 "wing" is not a wing, it's a spoiler.
It should come down to weather or not the air is "spoiled" before or after the top wing.

At least here in Sweden the general consensus amongst the racers is that the stock spoiler along with a upper, real, wing is effective. So that is why I'm a bit sceptical about it being counter productive without any data that can back this up.

However, I'm pretty sure that if you have no restrictions of the size of the top wing you might be better off with only that wing and design it accordingly. But most racing series have limitations of wing size and I can imagine in those certain cases keeping the stock spoiler can be effective.

I'm sure Vision motorsports are very good at what they do, and their cars are very impressive. But it is the same company that copied the 996 RSR front bumper openings and incorporated them into a 944 front bumper without realizing that some of the openings are in fact outlets not inlets! So I wouldn't trust their aerodynamical knowledge too much.

It would be great if we could get to the bottom of this, let's see if we can find someone with deeper knowledge of racing aerodynamics in general.
No one would be happier then me if it turns out the stock spoiler is counter productive, then I can remove it from my race car