2009 Acura ARX-02a

 

Images copyright Martin Spetz and 
Michael J. Fuller

Text copyright Michael J. Fuller
Acura ARX-02a, Sebring WDWT 2009Acura's interpretation of the '09 specification rear wing.  The reduction in span from 2 meters to 1.6 has significantly reduced rear downforce.  In fact, the ARX-02a was described as a "dog" in the first back to back test with the new rear wing.  It has since been optimized and most certainly some of what was lost has been regained through not only optimization of the rear wing, but of the rear end in general.
Acura ARX-02a, Sebring WDWT Test 2009It's hard to overlook the rear wing mounts.  The "swan necks" mount to the less sensitive, less important high pressure side of the wing freeing up low pressure side wing area and reducing airflow disruption.  

The reduction in chord from 300 mm to 250 mm for '09 (in addition to the span reduction) has led to the use of wing profiles with increased camber.  These more aggressive profiles are inherently more sensitive to wing disruptions which tend to result in very large flow separations.   The Acura's rear wing mounting solution is designed to reduce these surface disruptions as much as possible.

For the record, the rear wing mounts on the Acura are actually referred to as "Quillars", which is an amalgamation of "Question Mark Pillars."  
Acura ARX-02a, WDWT Test 2009Naturally the ARX-02a's rear end is much more aggressive than the ARX-01a/b.  We also suspect additional development work was carried on the rear end since the car initially rolled out in order to reclaim back some of the lost rear downforce.  Note that the diffuser strakes come all the way out to the trailing edge of the diffuser.
Acura ARX-02a, WDWT Test 2009The combined rear spoiler/gurney.  At the Wheels Down Winter Test the spoiler had a full length gurney.
Acura ARX-02a, Sebring 2009At the 12 Hours of Sebring, the full width gurney was replaced with a center gurney.
Acura ARX-02a, Sebring 2009Starting at Sebring, the rear diffuser strakes were trimmed back from the trailing edge of the diffuser.

©Copyright 2009, Michael J. Fuller