2011 HPD ARX-01e LMP1

Images copyright Acura and
Michael J. Fuller

Text copyright Michael J. Fuller
HPD ARX-01e, Sebring shakedown March 2011For 2011 Wirth Research reworked the very successful ARX-01 LMP2 chassis, applying it to the new-rules LMP1 category.  Mechanically the -01e was largely similar to the LMP2 car, but for accommodation of larger front and rear tires (the fronts were wider proportionally, but not the "rear" fronts of the ARX-02a).  The car's aerodynamics were redeveloped combining lessons primarily learned from the ARX-01c.
Highcroft Racing HPD ARX-01e, Sebring 2011The front end of the ARX-01e LMP1 shares general similarities with the LMP2 ARX-01 alphabet soup (a, b, c, d, and g): the undulating splitter shape, the front overhang dimension, the bodywork between the nose and the fender, the pushrod bulge, etc.  But all the bodywork outboard of the inboard bodywork split line is new.
HPD ARX-01e, Sebring 2011The ARX-01e's front fender is very blunt at the leading edge, allowing air to be directed outboard and to work across the deliberately  placed outboard aero elements.  Since the introduction of the -01a, Wirth Research has spent much effort in making this area of the car work well and it can be assumed this is key to a car's overall efficiency as well as front end aero grip.  There are quite a few aero elements mounted to the outboard corner, the diveplane, the vertical endplate that is attached to the outboard edge of the splitter, the vertical turning vane that attaches to the outboard face of the front fender, and the horizontal stay that steadies the gap between the vertical endplate and the front fender.
HPD ARX-01e, Sebring 2011At Sebring the ACO had a few questions for Wirth Research regarding the number of aerodynamic elements perched on the front end of the -01e.  Art 3.6.2 states that you're only allowed 2 elements maximum (2 pairs) and it turns out the ACO had been doing some counting and had come up with the number 3, arguably 4, when they looked at the -01e.  They counted the diveplane (1), the vertical endplate that is attached to the outboard edge of the splitter (2), the vertical turning vane that attaches to the outboard face of the front fender (3), and, if the ACO wanted to really be picky, the horizontal stay that steadies the gap between the vertical endplate and the front fender (4).  Initially the really questionable element in the ACO's mind was the vertical turning vane, and questionable from a numbers standpoint, not design execution.  After some discussion, all parties agreed that the vertical turning vane was actually part of the fender and shouldn't be counted towards the total.  And with the ACO not in a nit-picking mood, the horizontal stay was ignored from the total.

Note also that the diveplane is absent, as well as the lower filler panel that blanks off the lower portion of the outboard turning vane.  Highcroft experimented with a lower downforce setup, and eventually hit upon that for the race.
HPD ARX-01e, Sebring 2011With the diveplane in place, a filler panel is placed in the lower portion of the outboard turning vane.  When the diveplane was removed the filler panel was removed as well.
HPD ARX-01e, Sebring 2011The filler panel's leading edge portion is concave in shape.
HPD ARX-01e, Sebring 2011The high downforce louver package's very tall and full slab louvers.  Note the small louver slab on the inboard vertical face of the fender.  These were initially blanked off with a piece of aluminum bolted to the inside of the wheel well and we're unaware if the team ever unblanked them.
HPD ARX-01e, Sebring 2011The low downforce louver package were fewer in area and flush to the surface of the bodywork.
HPD ARX-01e, Sebring 2011The radiator inlet is heavily wasted in elevation view.
HPD ARX-01e, Sebring 2011The valance panel primarily has a rules compliance function.
HPD ARX-01e, Sebring 2011The side elevation shape of the trailing edge of the pontoon fender is deliberate as it matches the leading edge of the side pod and masks the waisted lower leading edge of the sidepod.
HPD ARX-01e, Sebring 2011The front diffuser is largely similar to the LMP2 car's, even down to the serrated trailing edge on the diffuser strake.  Having inspected the ARX-01g at Petit 2011, the only difference that could be noted was that the -01g's strake appeared to be shorter, this based on the visual distance between the first serration and the leading edge of the strake.  The trailing edge location was same/similar, inasmuch as the lower wishbone cutout appeared to be in approximately the same place (+/- 10 mm), except that the -01e's leading edge is further forward.  
HPD ARX-01e, Sebring 2011The -01e's outer splitter foot.  Edge sharpness must be important for performance, thus the replaceable aluminum inner edge.

ęCopyright 2011, Michael J. Fuller