Automotive Aerodynamics

CO2 Rail Car (tutorial)

Body construction

Images showing the creation of the main body, front and rear fenders, and cockpit

Tire construction

Images detailing the creation of the thin rim, thin tire, and final assembled thin wheel

Images detailing the creation of the fat rim, fat tire, and final assembled fat wheel

Finished Assemblies

2 thin 2 thick tires

4 thin tires

Drawing detailing and displaying views of the finished car

Data comparisons

Drag graph data

2 thin 2 thick tires

4 thin tires

Forces data table

2 thin 2 thick tires

4 thin tires

Flow simulation

Animation of flow simulation showing drag on car with 2 thin 2 thick tires

animation showing drag force on the car with 4 thin tires

Self designed Co2 Car

Sketches and planning

Constructing original prototype

Sketch of main body

Using revolve feature to make the body 3D

Cut extrude to create hole for Co2 cartidge

Cut extrude to create chambers for tires

Cut extrude to create axel holes

Full car assembly with tires and axels

Prototype simulation

Surface plot showing high and low amounts of drag

flow simulation gif showing directional drag force

Chart showing drag feedback

chart showing drag feedback

Redesigning

Adding angled covers to the roof of the car to add downforce and stop air from entering

Doubling the previous feature and adding variable filets to round it

Moving the guide hole for the string into the body of the car to run between the tires

Adding an extrusion in the middle of the car to bring the string through a gap

Adding more depth to the cartidge hole

Final assembly of the car to be used in testing

Surface plot showing high and low amounts of drag on the prototype, showing great improvements than the previous design

Data results

Chart showing the values of force in y and z directions, the drag of the car was cut almost into a third of what it was before.

Graph showing Y force

Graph showing force in the drag on the car

Data Comparisons

First test above Second test below

First

Second

Race Day

Before racing the car, supports from printing had to be fully removed and sanded down, and axels and tires were added after redrilling tire holes to ensure the right fit.

Below is the first day of test racing, the bullet car ended the day in first place for the thin tire competition with a time of 1.51s to reach the end of the track, this race had a maximum velocity of 71.8563 MPH

Below is the second day of test racing, the bullet car ended the day in second place for the thin tire competition with a time of 1.63s to reach the end of the track, this race had a maximum velocity of 49.3827 MPH

Below is the third and final day of test racing, the bullet car ended the day in first place for the thin tire competition with a time of 1.17s to reach the end of the track, this race was also completed with a 8g canister of cO2 rather than 12, this race had a maximum velocity of 75.4717 MPH and was the fastest race overall for the thin tire competition.

Calculations and derivations

Race 1- 71.8563 MPH

Race 2- 49.3827 MPH

Race 3- 75.4717 MPH

Average maximum velocity: 63 MPH

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