NASCAR’s Car of Tomorrow Changes the Rules (and Enforces Them With Precision Metrology)

The Car of Tomorrow, a new racecar style for NASCAR’s NEXTEL Cup Series, made its debut in March 2007 with much fanfare. Seven years in the making, NASCAR’s research and development center rolled up its shirtsleeves and conceptualized their dream template. Their ideal racecar would implement the ultimate in driver-safety features and refine component designs to improve performance baselines and overall competition. This was a tall order, but clearly obtainable in terms of the engineering and quality control technologies available.

Located in Concord, North Carolina, NASCAR’s research and development center is a $10 million state-of-the-art facility housing the industry’s best minds. The team has focused its attention and ingenuity on the overall safety of the sport without forfeiting what makes NASCAR more popular than apple pie—speed, team competitiveness, and fresh new faces entering the racing scene.

The Car of Tomorrow (COT) program has implemented measures to contain product costs and reduce the need to manufacture track-specific cars. NASCAR’s R&D team developed an adjustable rear wing and a front splitter, along with a refined body and a chassis measurement process, that culminate in a level playing field for large and small teams with varying amounts of investment dollars. Four COT body types have been approved: the Chevrolet Impala SS, Dodge Avenger, Ford Fusion, and Toyota Camry.

Standardize and verify
To ensure that all race teams are adhering to the exacting standards of the COT, NASCAR has introduced a chassis certification program that includes both dimensional control and metal thickness testing. “We verify some of the dimensions implemented for safety, such as the driver compartment space and more,” states Dan Kurtz, design engineer at NASCAR. “We also have standardized portions of the chassis and body, and those areas are validated, too. This approach allows the owner to lean more to the production side of the business, where they do not have to change things for every race like track specific cars or a new trend in aerodynamics. New teams can purchase a chassis from a local maker and know they are getting just as a competitive a car as the big teams. Those are the reasons the COT is here, with safety being the most important aspect.”

For the data acquisition and inspection process, NASCAR has implemented two GridLOK systems from ROMER Inc. (Wixom, Michigan) with portable coordinate measuring machine (CMM) technology. Used for in-place measurement of large parts, the solution consists of a seven-axis ROMER INFINITE articulating arm with standard probes, the ROMER exclusive patented GridLOK conical seat flooring system, and PowerINSPECT software from Delcam plc. The CMM arm rests on a mobile base and is moved around a chassis or car to gather data inside, behind, and underneath the measured object. The articulating arm has a measuring volume of twelve feet. Its integrated counterbalance provides a light, ergonomic feel to relieve operator fatigue during extended usage, plus patented infinite rotation in the primary axes for ease of use throughout extended inspection cycles.

“The ROMER system comes into play every day to verify dimensional controls that were implemented for safety and cost containment,” says Jerry Kaproth, safety coordinator at NASCAR. “NASCAR has standardized portions of the chassis and the body, and we validate all of those areas during the certification process.”

“Tolerances are much tighter on the Car of Tomorrow than ever before," states Kurtz. “Our objective was to make the tolerances reasonable so that every organization could build a car and reside within the tolerance, but to make it tight enough that teams do not build track-specific cars to one side or the other of the tolerance. By locking down enough dimensions, the teams will not be significantly different. They may bring different cars to different tracks to rotate them out, but there won’t be major variations in terms of aerodynamics and performance properties.”

GridLOK’d and ready to go
The GridLOK measuring arena resembles a large, invisible coordinate system ready for on-demand measurement. An operator can acquire precision sets of data with the same part origin while working within a 13 x 20-foot footprint. To achieve this, the system utilizes small (5/8-inch diameter) conical seats flush mounted in a steel plate resting on the floor of NASCAR’s inspection facility. Placed in 3-foot intervals, each conical seat is initially certified with a laser tracker during installation.

NASCAR’s Car of Tomorrow Innovations Safety features The Car of Tomorrow was built primarily with safety in mind: Double frame rail on the driver’s side with steel plating on the outside of the roll cage door bars to help prevent intrusion during impacts. Energy-absorbing materials installed between the roll-cage door bars and door panels. Enlarged cockpit­—roof is 2 1/2 inches higher and the cockpit is 4 inches wider. The driver also is up to 4 inches to the right of where he or she currently sits. Increased strength in the floorboard. An enclosed 360-degree steel containment tunnel for the drive shaft. Improved performance The Car of Tomorrow is looking to improve competition with a pair of unique aerodynamic pieces that teams may adjust at the racetrack. Rear wing The rear wing is an adjustable aerodynamic feature that provides better balance and control in traffic. It replaces the rear spoiler. The rear wing reduces turbulent air behind the car. It enables the trail car to race in “cleaner” air and promotes more passing. The rear wing angle adjusts between 0-16 degrees, enabling teams to change rear downforce to suit individual drivers and tracks. Various combinations and adjustments to sideforce-generating end plates and flat end plates allow for further at-track adjustments. Front splitter Teams can adjust the exposed portion of the front splitter fore and aft from 4-6 inches to impact downforce and aerodynamic balance. The front splitter is another element to achieve the aerodynamic balance that setup, driver, or the track’s changing conditions might dictate. The adjustable front splitter enables teams to tune the front downforce to suit individual drivers and tracks. The front and rear bumper heights have been equalized so they will be aligned if impact occurs. Cost efficiency With the adjustable rear wing and front splitter, along with a more defined body and chassis inspection process, teams will not need to build costly track-specific racecars. By using a more refined body and chassis measurement process, the need for track-specific car configurations is reduced. By providing the race teams with a “blueprint” to build chassis and bodies, teams should be able to reduce the amount of time necessary to fabricate cars. Manufacturer identity The Car of Tomorrow design has enabled manufacturers to have an increased product and branding opportunity with the Chevrolet Impala SS, Dodge Avenger, Ford Fusion, and Toyota Camry. NASCAR has improved the ability for manufacturers to retain their car identity by maintaining many of the characteristics of their production cars, such as front nose, grill, hood, window panels, and headlights. The Car of Tomorrow will more resemble a manufacturer’s production car than does the current racecar.

To activate GridLOK, the operator simply touches their ball probe into three different conical seats, and the CMM arm is instantly locked to the common origin. This “locking method” doesn’t interrupt software programs, and requires no use of buttons or computer keyboard selections. If the operator wishes to inspect in another area, he simply moves the arm, and repeats the locking procedure with the conical seats. No matter how many times the portable CMM is moved, GridLOK retains measuring accuracies, because the 3-D data acquired is relative to the same part origin with no accumulative error. This advanced technology eliminates the old “leapfrog” method used to gather data, which caused an accumulative deterioration of accuracy with every move of the articulating arm.

The concept becomes reality
Kurtz conceived and executed the new measurement procedures from top to bottom. When the COT design standards began to materialize, he built 3-D solid models in-house using Pro-Engineer CAD software. Based on the safety initiatives, engineers who worked on that project defined specific parameters for the driver’s cage. “We started off with just the center section of the car, which is the driver’s compartment and the passenger’s side of the car. We wanted to standardize that area, so a CAD model was created in-house,” says Kurtz. “We sent the CAD file to a manufacturer in Illinois, and had CNC-cut and -bent tubes delivered back to us. They are tabbed and slotted to fit together in the proper position to make up the center section of the car. Our most regulated areas are the center section, the rear clip, and the location of the fuel cell. The front clip is defined by rules about the symmetry, not actual locations, and located about a centerline.”

Once NASCAR set the rules, they had to devise a method to enforce them. Kurtz created a dimensional verification operation guided by a customized PowerINSPECT inspection routine. Mounted on the wall near each GridLOK inspection station is a large plasma screen displaying the software’s interface. Step by step, the software prompts for each strategic inspection point(s) with a detailed description, then advances ahead as each critical area is captured until the job is completed. Using the arm’s mouse mode and wireless features of the arm, inspectors are able to interact with the program using the large screen alone; no keyboard interaction is required. The macro-driven program not only ensures consistency between inspectors, but has proven to be an effective training tool as well.

Gathering chassis data
Kurtz inspected the first 75 chassises to prove out the concept, then Jeff Uran, a technical inspector at NASCAR, was brought in to learn the process. Uran was formerly a NASCAR Nextel Cup official, who would go to the track every week assigned to the chassis inspection department. His background as a pit road inspector was a huge plus. Assigned to the COT inspection team, he had the ideal expertise to work closely with Kurtz to refine and evolve the program.

With 95 percent of the teams in the local area, transporting a chassis to the R&D center for certification has been a fairly smooth process. Deliveries occur nearly every day for first-come, first served inspection. The chassis is placed on the GridLOK measuring area. Uran locks into the coordinate system and then centers the framework. Each team essentially defines their centerline by a receiver located on the chassis, and the receiver sits upon a defined fixture. The inspectors use a point-line-plane alignment system, and with a slight rotation to zero out on the Y-axis, the chassis centerline and the coordinate system centerlines are rectified and ready for inspection. Using the articulating arm and a 15-mm ball probe, Uran methodically works his way around the chassis gathering 3-D data for tolerance analysis. With nearly 400 inspections under his belt, Jeff averages about four inspections a day, but can achieve five full certifications per day when the traffic is high. Three other inspectors have been trained to use the portable inspection system.

In a typical session, Uran acquires more than 100 points in real time in approximately 15 to 20 minutes. Avoiding grind and weld marks, he starts the probing routine at the front firewall and proceeds to measure the intrusion plate, floorboard, firewall, fuel cell walls, oil casement, frame rails, transmission tunnel, drive shaft tunnel, and intrusion plate. Side members are also measured for a symmetry requirement. Because the frame rails are the foundation of the vehicle, they have the tightest tolerance, of plus or minus of an eighth of an inch.

Once the inspection is complete, the PowerINSPECT software populates an Excel spreadsheet report and the documentation is printed. Areas that failed the inspection will be highlighted for closer examination. The inspector will probe the area in question a second time to determine if a surface aberration or other anomaly caused the flawed dimension.

“After we measure and confirm that each chassis meets our standards, the framework goes back to the shop where the body will be installed,” says Uran. “If a team makes modifications or a vehicle is wrecked, the chassis must be returned to the R&D center for a complete recertification. If a car doesn’t pass, we have a verbal discussion about the problem areas, and the team is provided with detailed inspection documentation as to why the chassis failed.”

Concluding the certification
After the dimensional inspection, Uran proceeds to the metal thickness certification, strictly enforced by the governing body. The entire chassis certification process takes 1 ½ to 1 3/4 hours. If the framework passes the certification, NASCAR proceeds to apply 10 RFID chips to the chassis for automatic identification. The RFID technology records the serial number and all pertinent data. When the racecar appears at the actual race, all ten chips must be in place for scanning and certification.        

”When a chassis is presented to us by a COT team, a serial number is assigned to that car for its entire lifecycle,” says Kaproth. "Once certified, 10 RFID chips are immediately catalogued, then applied to specific areas of the chassis. When the car arrives at the racetrack, an inspector scans the microchips and proceeds to conduct their on-site qualification. Without RFID clearance, the car will not see the track.”

A work in progress
Sixteen races were conducted in 2007, and then NASCAR announced that the Car of Tomorrow would be used exclusively in 2008, a year earlier than planned. With the COT going full-time, NASCAR recognizes that more use will translate into more information for future design enhancements. In the first five events in 2007, NASCAR reported an average margin of victory of 0.505 seconds. When compared to 1.286 seconds in the same five races in 2006, they emphasize that the COT program is on the right track.

“The Car of Tomorrow initiative allowed us to expand on the knowledge base we were accumulating on a race-by-race basis. At the same time, we took the opportunity to look at other important aspects from the racing community as a whole. We wanted to make strides in safety and competitiveness, and at the same time improve the financial health of the sport. In the very first COT race at the Bristol Motor Speedway, 59 cars raced within 6/10 of a second of each other. It was extremely competitive to make the final field of 43. And it is very encouraging to see that some small and new teams have done fairly well to date,” concludes Kaproth.

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