Automotive Aerodynamics

Automotive aerodynamics is the study of the aerodynamics of road vehicles. Its main goals are reducing drag and wind noise, minimizing noise emission, and preventing undesired lift forces and other causes of aerodynamic instability at high speeds. Air is also considered a fluid in this case. For some classes of racing vehicles, it may also be important to produce downforce to improve traction and thus cornering abilities.

CO2 Rail Car (Tutorial)

BODY CONStruction

Images of the main body, the cutout of the body, the front and rear fenders, and the cockpit loft.

TIRES

Images of the front thin rim and tire.

Images of the thick rear rim and tire.

Finished Assemblies

2 thin 2 thick tires assembled.

All 4 thin tires.

Drawing detailing the views of the finished car.

Data

2 thin 2 thick tires

Graph showing the drag of the car with 2 thick and 2 thin tires.

4 thin tires

Graph showing drag with 4 thin tires.

Table showing statistics with 2 thick and 2 thin tires.

Table showing statistics of 4 thin tires.

Simulation with 2 thick rear tires.

Simulation with 4 thin tires.

CO2 Rail Car - Personal Car

THE DESIGN

FIRST Attempt

First simulation, the front fender and rear wing were producing a large amount of drag,

SECOND Attempt

To assist in aerodynamics, the front fender was straightened out and angled lower, and extrusions were added to the front and wing to guide the air, eliminating some of the dirty air. The rear wing was angled down more, since the air was getting stuck at the front of it.

Images of the rear wing and the linear patterns of the extrudes.

TEST PRINTS

First

The first print tested the rear wing, cartridge hole, axle hole, and leader holes. The wing, cartridge hole, and leader hole worked, but the axle hole was too small.

Second

The second test print tested the front lip, front fender, and axle hole. The axle hole was the correct size, but the extrude around the wheel was not a big enough radius. The extrudes on the lip worked as well.

Third

The third test print tested a deeper fender around the wheel and the axle hole once more. The wheel fit smoothly into the fender, and allowed for perfect rotations.

Simulation results

The original simulation had a large amount of drag and a large amount of lift.

The improvements cut the lift in half and eliminated a small amount of drag as well.

Table with the values from the first attempt

Table with the values from the second attempt

Graphs showing the drag and lift of both simulations, first attempt on the left and second attempt on the right.

Gif of the slice simulation, how the car will be printed.

Drawing of the body of the car.

Finished Product

Post-Processing

To post process my CO2 car, I sanded heavily inside the wheel wells to make sure no friction is caused between the tire and body. Where possible, the body was sanded as well to remove a fraction of drag.

Shown under, the car was fully spray painted with red paint to look better, as well as partially smoother.

Finished car with wheels attatched.

Gif of mine (Right) and Eli Robinson's (Left) cars during the spray-painting process.

Still shot of the spray-painted cars.

RACE DAY

Race 1

View from the floorline.

Slow-motion of the start.

Race 1 was vs. Bryce Valencia (Black Car), my time was 1.41 seconds, his was 2.39 seconds. My maximum velocity in this race was 54.30 mph.

RACE 2

Raced against Colin T. my time was 1.541 seconds, his was 1.069. I lost this race and was moved to the losers bracket for the 3rd round. My maximum velocity this race was 51.26 mph

Beginning of race view

View closer to the end of the race

Race 3

Raced against Francisco in the losers bracket, my time was 1.341 seconds, Francisco's was 1.321 seconds. I barely lost this race. My maximum velocity this race was 56.049 mph.

Close-to-the-ground view at the start of the race

Slow-mo video of the race

View close to the end of the race, very close

Calculations

Image of the calculations for max velocity.

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