In
April of 2006 Acura announced their intention to enter the 2007
American Le Mans Series with a new LMP2 challenger. Wind tunnel development commenced in June of that year at the Auto Research Center (ARC) wind
tunnel in Indianapolis, Indiana. The
aerodynamics program began by baselining the Courage LC75 in 50% scale.
Honda Performance Development (HPD) had evaluated
both Lola and Courage's current offerings, coming to the
conclusion to utilize the Lola as the program's chassis-side
control with the Courage LC75 as the starting point for car
developments. All chassis design work would be carried out by
UK
based Wirth Research headed up by Nick Wirth. Engine design
and
development was the responsibility of Honda Performance Development
based out of Santa Clarita California and over seen by Stephen
Eriksen.The Courage LC75 evaluation included a full scale wind tunnel test at the Stuggart University in August. One of the items to come out Stuggart University LC75 wind tunnel test were bodywork modifications necessary to mollify the car's propensity to porpoise. Says Nick Wirth, "The Courage test was so memorable because the basic car porpoised so badly it nearly leaped off its mounts and we could have lost it down the tunnel!" By October of 2006 CFD development was up and running and would parallel the ARC-based scale program. Ultimately 80 days of wind tunnel testing would be conducted throughout the ARX-01a program at ARC.
By January of 2007 the first development items were making it onto the car and the Courage LC75 mule-car was testing new Wirth Research designed suspension while the definitive Acura bodywork was still in development. It was this configuration that debuted at the Wheels Down Winter Test. By early February the "Acura ARX-01a" bodywork was available and pre-Sebring testing of the definitive specification commenced. A final full scale wind tunnel test was conduced at Stuggart University in February in order to give the Acura-spec bodywork a once-over, confirming the improvements made over the LC75.
According to Nick Wirth, given the number of changes to the Courage chassis, "The ACO requested the car be rehomologated an ARX-01a as it was so extensively changed from the LC-75, yet the monocoque was still run under the Courage homologation." The ARX-01a utilized the Courage LC-75 monocoque, front crash structure, and gearbox with a Courage designed Acura engine bellhousing. Dimensionally, the Acura ARX-01a was on the same wheelbase as the LC75 (as would be the ARX-01b) but the front overhang was increased to the maximum and the rear bodywork shortened (though the wing position stayed the same at the maximum 750 mm rear overhang). The ARX-01a was also designed to the maximum width and was around 50 mm wider than the LC75.
In 2007 Highcroft and Andretti Green Racing ran the ARX-01a. A surprise debut victory at Sebring was the season's only win for Acura.
Development of the ARX-01b began during the summer of 2007 and was carried out entirely in CFD. A host of changes over the -01a included; bodywork, front and rear suspension, Wirth Research designed gearbox with integral bellhousing (though same internals as -01a), front crash structure, upgraded monocoque internals, and an Acura steering system. The new front crash structure required a new crash test for certification and subsequently the monocoque was homologated as an ARX-01b for 2008. The significance of the use of CFD for this development package might soley be down to the fact that at the time the LMP2 model was more than likely tied up in developing the future Acura ARX-02a LMP1.
The ARX-01b raced successfully in the hands of De Ferran, Highcroft, and Fernandez racing throughout 2008 recording 6 wins and only just missing out to Porsche in the Manufacturer's Championship (213 points vs. 214). Fernandez Racing continued to field their ARX-01b during the 2009 season while De Ferran and Highcroft stepped up and into the ARX-02a.
