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Chevrolet Corvette C8.R's aerodynamic breakdown.

Chevrolet Corvette C8.R's aerodynamic breakdown.

Posted by Sean A. on Jan 22nd 2021

A racecar's performance relies on the function of every area of the cars operation. This includes, top speed, cornering speed, braking, tire wear, and overall stability. Each of these operations are directly affected by the vehicles aerodynamic performance. 

We all strive to "cheat the wind" when talking about hyper-efficient aero designs, however, thanks to the immutable laws of physics this is not really possible. Engineers are constantly re-designing aero parts to better manage airflow effectively and harness the winds power when possible. In terms of racing, this is a much more difficult task as they are required to stay within the rules of the vehicles class limits. This is exactly what the corvette racing team did with the C8.R.

(Source: Corvette-mag.com)

The teams goal was to maximize downforce and minimize drag equally at all speeds. They also needed to provide sufficient cooling to the engine, transmission, brakes, air-conditioning condenser, and other components throughout the car by diverting air through the vehicle.

One of the most testing parts of enhancing streamlined features is the fact that sometimes the design objectives contradict each other. For instance, while it's alluring to both diminish drag and increment downforce, accomplishing the last will in general apply an undesirable effect on the previous. Over the long haul, engineers have discovered creative approaches to progress alluring attributes while limiting negative side-effects.

Aero testing started long before the first factor for Chevy’s C8.R development automobile was manufactured, inside intensely effective computer systems directed by means of equally effective programs using numerical evaluation and data structures. Computational Fluid Dynamics (CFD) is the department of computer-aided engineering that permits for this. CFD analyzes fluid drift in accordance with its velocity, pressure, temperature, viscosity, and different bodily properties, with the use of extraordinarily state-of-the-art mathematical equations. CFD evaluation was utilized in the Corvette racecar’s individual elements and sub-assemblies, in addition to the automobile in its entirety.

Another advanced tool used to analyze aerodynamics is Chevrolet's state-of-the-art driver-in-the-loop (DiL) simulator. The machine allows for racers to virtually "drive" a developing race car on the same track it will race on.

(Source: Corvette-mag.com)

“This is the first time we’ve been able to drive a racecar before it existed…in real life,” explains Corvette Racing pilot Tommy Milner. “[With the C8.R] we could drive iterations of it based on theories and what engineers thought would work. That, for me, was an entirely new experience. Being a part of that has been the most fun part of the entire process."

“Trying different fundamental changes in the car and seeing what our window is to work within has been great,” Milner continues. “It’s a tool for the engineers to understand what we, as drivers, can deal with, from the mechanical side to the aero side. Just like the DiL is a tool for us to get up to speed at a track, it’s a tool for the engineers to try things that take too long or are just wild ideas that you can’t try at the track.”

After all the calculations and computer modeling it was time for the physical testing to begin. as with all of the teams other vehicles, the C8.R's testing was done both in the wind tunnel and at various tracks across the country. Although Corvette Racing engineers have an immense record of knowledge built up from their almost a quarter century of experience, the new eighth generation of Corvettes dramatically changed the architecture of the vehicle which meant there needed to be some aerodynamic considerations. 

The most noticeable change was the relocation of the engine to the rear of the vehicle. This resulted in a large amount of space in the front end, allowing engineers to improve upon the front diffuser and its support structures. On the opposite end of the car is a more compact gearbox designed by Xtrac specifically for the C8.R also freed up more room for the rear diffuser.

While both the front and rear end were optimized, it is important that there is a balance between both. With a Clean-Sheet design,  creating downforce at the front end is easy given the car is moving through clean air. The problem lies in the rear as that area never has the same volume or quality of airflow. The C8.R's carefully sculpted under-floor and precisely designed body allowed for more airflow to reach the rear wing and diffuser creating a higher downforce while keeping the front and rear balanced. 

IMSA GTLM and FIA GTE rules allowed considerable freedom with how the airflow is fed into the engine and cooled the car's multiple components so the team were able to find new more efficient ways of directing the air. Unlike the street driven C8, which takes in engine air through the body side scoops, the C8.R intake is a forward facing scoop under the base of the rear window. This design was not used on the street application due to the fact it blocks the drivers rear view. Corvette Racing Team decided to use a rear facing camera as the only rear sightline. Therefore the vehicles engine scoop always has a streamline of fresh, high-speed air without interrupting the airflow to the rear wing ensuring its effectiveness.

(Source: Corvette-mag.com)

The use of the rear engine scoop freed up the side scoops to perform its job elsewhere, including providing cooling air to the engine and gearbox. In previous corvette models the separation of the engine from the transaxle made keeping each components temperature level an easier task. Now that the engine and transaxle are both located in the rear, keeping each one cool has become a considerably more difficult job.

Previous Corvette racing models had much of their ancillary components cooled passively, meaning, they were cooled by the air circulating around them. The C8.R clustered these parts with the powertrain causing the development team to use heat shielding and active cooling ducts which directs air through the side scoops to where they are most needed.

Comparatively to other corvette models, the C8.R had its engine radiator located in the front by the Frunk storage area. The air comes through the center mounted grille, passes through the radiator, then exits through four ducts. There are two ducts on the hood by the windshield and two ducts behind each front wheel. The relocation of the engine to the rear of the vehicle allowed for these ducts to be put in place ensuring that the development team maximized the efficiency of airflow that front-engine corvettes could not do. The front-engine corvettes lacked sufficient space to route airflow out the sides. The older models routed all the air through one large duct on the hood.

(Source: Corvette-mag.com)

"The size of each duct exhausting air that has passed through the radiator has been balanced to meet the aero requirements of the car,” explains Corvette Racing Program Manager Ben Johnson. “It represents a fairly novel concept from the aero team to capitalize on the architecture of the car.”

Come the end of 2019, the new vehicles homologation was finished, all developments were set in place. more than two years worth of design, development, and testing brought a new-generation of Corvette Racing that incredibly outperforms anything that came before.

Due to the Balance of Performance adjustments rule by IMSA and the FIA/ACO the C8.R will not go around the track dramatically faster than the C7.Rs. However, the improved aerodynamics will make the car felt in other ways. This means the car will be more fuel efficient, have a greater tire longevity, and will be more consistent over the entire duration of each stint. This will also allow for the team to respond to different ambient factors and track conditions more effectively. In whole the C8.Rs aero improvements will play a crucial role in this vehicle's success on and off the track.