2006-2008 Audi R10

Images copyright Pat Michl, Photos @ Vector Trust, and Michael J. Fuller
Text copyright Michael J. Fuller

Sebring 2006 Sebring 2003
It is believed that following the 2003 Le Mans the Audi boys took the winning Bentley LMGTP back to Ingolstadt for a thorough post race inspection.  And while the R10 and Bentley LMGTP do not visually resemble one another, the R10's cooling architecture is remarkably similar to the 2003 Bentley.  The front suspension is shrouded with air traveling above and below as it flows to the radiator inlet.  Masked beneath the suspension shroud is the trailing edge of the front diffuser which ends approximately at the front wheel centerline.  In this comparison shot, note how much lower the pick up point on the upright is (using the suspension shroud as the visual cue) on the Audi compared to the Bentley.
Audi R10, Sebring 2006The Audi R10 was photographed during the 2006 Wheels Down Winter Test running in this configuration.  Notice the blanking panel redirecting the lower air flow up and over the front wishbone shroud.  Audi's Technical Director Ralf Jüttner indicates that this panel was briefly tried to test the effects on cooling, but that it, "Has not been taken any further thereafter."
Salt Lake City 2006The torsion bar front suspension.  We can also see the vertically mounted primary dampers (Ohlins).
Sebring scrutineering 2006The lower profile of the front diffuser has a short flat area just aft of the leading edge becoming a large radius up sweep to the trailing edge.  Overall the R10's front diffuser cross section is a non-symmetric wing profile that skirts Art 3.6.1 by having a vertical step on the top cross section, just behind the leading edge of the splitter.  That step alone is the work around and the ACO's Daniel Perdrix has confirmed this.  Though one wonders how small that step could be before the ACO themselves no longer agree with that ruling.
Audi R10, Petit Le Mans 2008These small surface mounted vortex generators, affixed on the underside of the front diffuser, were spotted at Petit '08.  As a generalization, VGs such as these are used in situations where either the primary design is faulty (see Nissan NPT-90 GTP underfloor, page 147, Inside IMSA's GTP Race Cars..., Martin & Fuller, Motorbooks International, 2008.) or, as more likely in this case, the design is being pushed beyond its original performance window.
Sebring 2006 Here we can see the rear end of the entire diffuser/nose box/front bodywork assembly as well as an end view of the diffuser.  The primary diffuser upsweep has only two strakes located adjacent to the front wheel (in fact the strakes have a clearance bulge to compensate for the wheel's steering travel they are located that close to the tire, see image below).  The strakes end at the front wheel centerline.
Sebring 2006
Sebring 2006Note the gurney attached at the trailing edge of the diffuser.  This image also gives an idea of the height of the trailing edge of the diffuser upsweep.  Finally, we can also see that the diffuser comes to a pointy trailing edge.
Sebring 2006The gurney helps improve diffuser performance and front aero grip though is merely a aero balance tuning device and was only present on one of the chassis.  Though by 2008 the front gurneys had grown quite large, and in conjunction with ever increasing rear body gurney heights (and rear "Spa wings"), signify a large increase in overall downforce on the R10 throughout its 3 years of competition.

Audi R10, Petit Le Mans 2008The front diffuser gurney has gotten taller since '06 and the brake duct blanking panel has grown as well and is being used as an additional method to generate front downforce.
Audi R10, Petit Le Mans 2008These vertical strakes (left hand here) first appeared at Petit '08.
Sebring 2006The entire front bodywork/crash structure/front splitter can bolt off as one in a matter of  seconds to allow for very easy access to the front torsion bars for quick setup changes, not to mention rapid race repairs.

©Copyright 2008, Michael J. Fuller