2006-2008 Audi R10

Images copyright Pete Lyons, Pat Michl and Michael J. Fuller
Text copyright Michael J. Fuller

Sebring 2006 The R10's particulate filters have grown in diameter since the car's introduction (note the bulge in the engine cover and compare to inset image below).  The placement of the exhaust is located to beneficially influence the trailing edge flow of the rear diffuser by injecting high velocity airflow into the air stream.
Audi R10 debut, Paris, France, December 2005
Sebring 2006The rear diffuser gurney is fixed height (though replaceable/removable) where as on the R8 it could be adjusted up or down as needed.  By late 2007 the rear gurney height had gotten quite tall, substantially so, and was an indication of higher overall downforce levels being run.
Sebring 2006In this shot you can see the mandatory plank that is bolted to the underside of the car.
Sebring 2006The R10's high camber rear wing.
Sebring 2006Louvers accompany the rear fender.
Audi R10, Petit Le Mans 2008At the 2008 Spa Le Mans Series event the Audis were running in a slightly revised aerodynamic spec which consisted of a simple add-on "wing" mounted between the rear fenders at the very trailing edge of the engine cover.  These wings took on the name, "Spa wings".  Subsequently this package became the standard configuration and was raced at Le Mans and all tracks (Le Mans Series and American Le Mans Series) post-Spa.    
Audi R10, Petit Le Mans 2008Having a closer look at the wing, it is a simple parallel extrusion in cross section without a differing top and bottom chord line (i.e., not a true wing but we'll use that wording from here out for clarity sake, I mean what else are we going to call it?).  Overall it seems rather crude in execution and is very simplistic.
There was some initial thought that the windows in the trailing edge of the bodywork might allow for positive aero interaction of the wings with the trailing edge of the under floor, that this might allow the wing to potentially "see" the trailing edge of the tunnels.  On further discussion it now appears that the windows are in fact the wing's only reason for being from a regulations standpoint but don't impart any significant increase to the installation's overall performance.  We understand that, according to Audi, the wings are in fact "cover panels" thus making the car in compliance with Art 1.5.2 which states that as seen from above, no mechanical components can be visible.  

In general, the Spa wing allows a reduction in angle of the primary rear wing flap for less drag but similar levels of downforce.  Observations of the rear wing gurney height back this up as that has now gotten smaller.  While body gurneys can be used effectively to increase overall downforce, in Audi's case there are now more efficient ways to do that.

Interestingly enough, a cursory read of the regulations and one really questions the legality of such an aero device is based solely on the wording in article 3.6.2 which states in rather plain language:

3.6.2 - No aerodynamic element can be added on the bodywork apart from :

- Two aerodynamic elements maximum at the front of the front fenders provided that :

• They do not obstruct the driver's view
• They do not mask the headlights ;
• They are not situated more than 600 mm above the reference surface ;
• They are approved by the manufacturer and the ACO (homologation form of the car).

- One “Gurney” at the rear of the bodywork.
- The rear wing described below.

So it seems rather clear that said add-on device isn't, a.) an element attached to the front fender, b.) a rear body gurney (the cars still had the standard trailing edge gurney being run in conjunction with the new device), or c.) a rear wing.  So naturally there are questions as to how Audi defined this aero device and then to what standard the ACO accepted it.

ęCopyright 2008, Michael J. Fuller