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Fast Car, Fast Development

Callaway Cars' C12 is a lot more than just a souped-up `Vette. Though still a relative of the current generation C5 Corvette, the C12 was completely reengineered to race at Le Mans in the GT2 class (which requires entries to be street-legal production derived cars). This gave the engineering team the challenge of designing an ultra-high performance vehicle in which everything new still fits on the original platform. They accomplished this in just four months thanks to the use of powerful CAD technology.

Nov. 1, 1997—Callaway stylist Paul Deutschman's full-sized clay model is approved. With team members scattered across the globe, Internet communication across time zones accelerates development. Callaway Cars' president Reeves Callaway: "We were able to assign tasks based on who was most capable rather than who was most convenient and actually turned what used to be a disadvantage—the geographic and cultural distance between our team members—into the advantage of working nearly 24 hours a day."

November 1997—All-new body panels will have to fasten to the original car's frame. Likewise, new suspension and a bigger brake package will have to fit in the space that the original systems had occupied. Pro/ENGINEER automated product modeling software is used to generate designs.

The car is widened to the full two meters allowed in international racing by custom making the A-control arms. Consequently, the steering geometry, the rear camber and caster adjusters and the driveshaft all have to be changed or redesigned. The team also needs to design the enhanced suspension and brake packages. Three-dimensional models that observe the fixed reference points are used with a range of visualization, assembly and motion programs to make sure that the new systems fit onto the pick-up points of the frame. Interferences are spotted and fixed before anything is built. Callaway: "For each prototype we didn't have to build, we saved several weeks."

laser scan of clay model

Dec. 1, 1997—A laser scan of the clay model is completed and e-mailed to Lepage Design's Stephane Lepage, who begins finishing the "digital clay" with Deutschman. The software package from Parametric is used.

December 1997—The hourglass shape of the clay model was too pronounced; a more subtle flow of the door into the front and rear fenders is needed. Lepage makes the change to one surface and the software automatically updates the rest of the model. LePage: "You can build surfaces that are driven by curves and splines, and even by parameters and formulas. When you modify these, the surfaces are modified too, and the design process becomes very supple."

Dec. 24, 1997—Modeling of the car body is completed. To prepare for manufacturing, Lepage uses the software tools to quickly add features, such as return flanges to the body panels, and to ensure fit by trimming, removing gaps and revising dimensions.

At 9:00 am, the first IGES file with data for the car's door arrives in Germany. The IVM staff imports the data into an in-house program, which creates CAM programs. The first completed door panel exits the mold within 48 hours of the data's arrival.

January 1998—Manufacturing the rest of the composite body panels goes smoothly and quickly; no molds have to be reworked.

March 3, 1998—The Callaway C12 debuts. In the wake of a successful project, enthusiasm is high for new challenges. Callaway: "The feeling in the automotive industry is that no-one is willing to go from the screen to the tool without seeing the thing in three dimensions, but we're getting there."

The Callaway C12: Anatomy of a Supercar
SpecificationsFront engine, rear drive, two-seat coupe
FrameTorsion-resistant hydroformed steel frame
BodyExterior skin made of GRP/Kevlar hybrid composite
Suspension4 wheel independent suspension system with upper and lower A-arms
BrakesInternally ventilated four wheel 355 mm disc brakes with ABS
Top speed188 mph (302 kph)
0-60 mph acceleration4.3 seconds
EngineAluminum alloy, 16 valve, 90° V-8, 5.7 L
Bore/stroke99 mm / 92 mm
Rated horsepower440 bhp @ 6300 rpm
Maximum Torque415 ft-lbs @ 5200 rpm
Compression ratio10.3:1
TransmissionRear mounted 6-speed manual transmission
Transmission ratios:
1,2,3,4,5,6,R
2.66:1, 1.78:1, 1.30:1, 1.00:1, 0.74:1, 0.50:1, 2.90:1
Rear axle drive ratio3.42:1
MeasurementsLength 4,852 mm; Width 1,998 mm; Height 1,192 mm
Wheelbase/wheel track2,660 mm/1,650 mm
Curb weight1,480 kg
TiresPirelli 295/30 ZR 19