2009 Acura ARX-02a
Images copyright  Michael J. Fuller
Text copyright Michael J. Fuller
Acura ARX-02a, Sebring WDWT 2009The wide front tires imparts a much bulkier look to the front end of the ARX-02a.  And they come with some draw backs; they are slower to reach operating temperature (such as on a restart), there is an increased possibility of hydroplaning in the wet, and there are negative interactions with the front diffuser.  Though Wirth Research ultimately felt these draw backs were more than made up for by the gains, and indeed WR claims to have overcome any and all deficits.

The Acura ARX-02 was designed to be several hundred pounds under the minimum weight in order to be ballasted to the minimum of 900 kgs.  This was done primarily through a monsterous 270 lb piece of steel ballast (24" x 36" x 1") located on or near the front wheel centerline.  Along with the light weight engine, the ballast plate helped move weight distribution forward,  as much as 53%, though slightly less was found to work best, allowing the wide fronts to work to their optimum.
Acura ARX-02a, WDWT 2009The 37/71-R18 Michelins.  The ARX-02a never benefited from properly developed tire compounds for the wide fronts.  We note with irony that in the intervening years Michelin was finally motivated to develop bespoke wide front compounds with the subsequent adaptation of the concept by both Audi and Peugeot.
Acura ARX-02a, Sebring WDWT 2009Front dive planes were always a feature on the LMP2 Acura; never were they raced without some configuration of dive planes.  The ARX-02a's are similar in concept, but they are much more hard wired into the the design and less a way of balancing the car.  I'll suggest there are potentially other methods of altering the car's front aero balance?  What leads me to that conclusion is that they are much thicker (and thus durable) than the previous diveplanes as seen on the LMP2 cars which suggests a need to stay on the car.  Indeed, it's my understanding that the -02a's diveplanes acted as drag reducers, creating a vortici that beneficially interacted with the airflow moving down the side of the car.  That is, it would be detrimental to the car's performance if they were "pinged" off mid-race because of car to car contact.  The diveplanes are tapered on the outboard edge to improve aero performance.
Acura ARX-02a, Sebring WDWT 2009The Acura's bare nose with diveplanes missing reveals further proof of the permanence of the diveplanes.  The diveplane unit is bonded onto the front of the fender, thus making them effectively permanent
Acura ARX-02a, Sebring WDWT 2009The entire louver section on the ARX-02a is somewhat different than on other LMPs seen previously.  Instead of a louver panel that fits into a recess in the fender, the entire top portion of the fender is integrated into a "cap" and can be unbolted and replaced as needed.
Acura ARX-02a, Sebring WDWT 2009At Sebring 2009 a partial blanked/louvered panel was used.

ęCopyright 2009, Michael J. Fuller