I'm on a real computer now. I'm still not seeing the wing on AB's car. Looks like a modified Elise diffuser to me, with a gurney added to the center section.

 

 

Could be wrong, wonder if its been changed? Thought there used to be an open section forward of the diffuser/wing/whatever it is, but you're probably right.

 

I've often wondered if you could do both... Using the picture of the c6r vette as a reference. One could use the a diffusor like this, albeit a large one with more clear space behind it... and drop an aerofoil in behind/beneath it. Although I'm not sure one could achieve this with the proper angle of egress for the speeds for our typical none of the horsepower speeds.



the C7 used a similar setup but it was adjustable instead of fixed angle.


Just to show the evolution - The c5r had a more standard diffusor/strake setup that us meer mortals are more familiar with.

 

A diffuser only really works well when you also have a flat under-body. Unlike a standard wing, it is free aero as the only induced drag is already there (the car).

edit--check out that massive transaxle cooler with fan on the back of the Corvette.

 

right... i was adding to the discussion on the previous page regarding aerofoils within the egress airflow of the under tray and diffuser.

 

Wasn't the change to the new-style short/wide flat rear planes due to a change in the rules by IMSA that no longer allowed diffusers with vertical fins?

So an airfoil builds pressure on the top surface, and for a diffuser you want less pressure/faster moving air on the underside. These two interests clash a bit. A pressure map of a typical diffuser shows the majority of the vertical force happening at the beginning of the angle change, so that is where you would least want to have an airfoil undernath - that's ok because that wouldn't work anyways as there is no ground clearance there.
So then looking further back... even though the forces are towards the front of the diffuser, the air's behavior all along the length of the diffuser dictate how effective it is. Placing the airfoil underneath the diffuser surface near the back (like the BMW on the last page) is going to create an obstruction to the diffuser's airflow as the topside of the airfoil slows air and builds pressure in the region between it and the diffuser.

I think the best application of the idea would be for the airfoil to be placed behind the diffuser exit. Use a wing with swan-neck style mounts or mount via endplates, suspended from the rear of the car, and the wing aoa adjusted for the airflow angle coming out of the diffuser. This way, the pressure build up above the wing can occupy the space behind the center of the rear of the car, and the diffuser's function isn't jeapordized.

That's how I'd do it at least.. but if the concept can work or not? Only one way for someone to find out.

-Ryan

 

So this might not be aero related but, it is my thread. I think it's cool how the process of a test vehicle. So when I was at the Porsche Museum in Stuttgart Germany they had there Porsche 918 test car on display. So here are my pics

Production 918










918 Test Car

 

Bloody Hell that has Mad Max or Back to the Future written all over it!

Pretty cool and intriguing to see that.

 

How come my race cars always look more like the test mules than the production cars?

 

While reading through the thread, this called to mind an article I read a while back. After digging it up, the article doesn't appear to have been referenced in the thread yet after some in-thread searches.

It's one of the most appealing and creative uses of unrestricted aero that I've ever seen.

For My Ally Is The Force, And A Powerful Ally It Is - Speedhunters

Not much obvious on the outside:


But inside:





Using the low pressure behind the car to suck air out from under the car. Lots of downforce with extremely minimal addition in drag, if any at all. It might even be a drag reduction since the low pressure zone behind the car is partially pulling on air under the car, and less on the car itself

 

This is something I am working on this weekend. I will be placing a quite a few NACA ducts in my underbody to help move air for cooling.

Before resin



and finished for now

 

What are you trying to achieve with the fibreglass rear?

Is there more to come?

 

The one idea that pops into my head is to use the suction form the rear as exit for the transmission tunnel heat when closing off the floor. Just a couple of big air ducts from the diff across the trunk to the plate area. Could that be efficient enough to seal the floor completly (just have exhaust cooling exiting above the diffusor)?

But that's might be what RJ's showing?

 

 

I should show those NASA jocks how to REALLY torture the air with a Hornet!

 

In the article I found these pictures, they were talking about outer most part of the diffuser isn't getting proper flow.

Rear Diffuser Issues - Forum - F1technical.net

 

seems as though the strakes aren't doing what they are designed to do.

 

So I was looking around again at diffuser designs and I seen what slimjim8201 wrote on f1technical.net.
Interesting data on Straight, convex and concave diffusers. Each are tested at 5, 10 and 15 degs.

 

From that first set of images it looks like the strakes need to extend in front of the start of the diffuser. And thats on a car that already has a flat floor. Imagine how much of a disaster it looks like on a car without a flat floor.