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 Construction

Body Construction

Front Wheel

Rear Wheel

Axle / Washer

CO2 Cartridge

Rail Car Assembly

Engineering Drawing

Flow Simulation

Flowsim Animation

After running the assembled CO2 car through the flowsim, I went back into the assembly and swapped out the big rear wheels for the same ones used in the front.

Flowsim Animation for small wheels

Custom Car Design

Thumbnail Sketches

Before designing my car in SOLIDWORKS, I drafted down some ideas progressing through what I hoped the car to look like in the end.

This is the general concept I plan on using for the car. It consists of a large, hollow tube that cuts through the middle of the car. This should help prevent large vortices from forming in the back, increasing aerodynamics. I drafted two possible ideas for how the wheels would attach to the car, with the axlerod cutting through the center being the least preferred option.

This section shows some notes I took during the in-class lectures on automotive aerodynamics as well as some more concept drawings I made during the lessons. The direction of airflow is clearly labeled in the pictures. I noted that having the vent smaller in the back would help get the air flowing faster, however the cars themselves are really small so I do not plan on going through with that one. Due to the requirements that the wheels have to be a specific distance above the ground, I am putting the hollow tube on top of a raised base. Initially, I planned on using a spoiler, however I do not know where I would be able to put it given the unique design I am going through with.

This shows the updated design after combining the large air tunnel, the raised base, and the wheel and guideline holes. The guide hole is needed because the car will be racing along a straight track with a string weaved through the bottom in order to hold it in place. The top part where the CO2 chamber goes is slanted upwards to allow air to flow smoothly over it.

Another note I made during the aerodynamics lessons in class is that a lot of formula-1 cars have diffusers in the back which pulls air upwards, helping with downforce. Downforce is a factor I must consider because we are using CO2 rockets to launch these cars at high speeds and I dont want mine to end up flying. These things arent very big, only a couple millimeters across.

A bottom view of the base of the car, with holes for the guideline and axlerods shown. I decided to give the base the curved shape to reduce weight and give the air a smooth path the follow as the car moves forwards. Many race cars have this needle design to them in order to allow them to cut through the air effectively. My hopes is that I can funnel as much air into that central tunnel as possible, however there will still be dirty air underneath the car that I would have to deal with. This curved shape will hopefully eliminate some of that dirty air.

Race Day