The STF Racing Car

Below you can see our finished car design. The image below is a photo of our newest car with paint and stickers applied.

STF Racer

What is Drag?

Drag

Drag is a force trying to prevent rapid movement of a car through the air. This force is generated through a difference in pressure between the front and rear of the vehicle. This pressure difference acts of the frontal area of the car to give the drag force — hence the larger the frontal area, the greater the drag.

The following equation can be used to calculate the drag on an object:

Drag Equation

What is the Bernoulli Effect?

The Bernoulli Effect means that if a fluid (gas or liquid) flows around an object at different speeds, the slower moving fluid will exert more pressure than the faster moving fluid on the object. The object will then be forced toward the faster moving fluid.

Indy cars use this principle. The shape of the chassis is similar to an upside-down airfoil. The air moving under the car moves faster than that above it, creating downforce or negative lift on the car, which helps it take corners faster.

What is Lift?

Velocity is a vector quantity — it has both speed and direction. Changing either the speed or direction generates a force. Lift is a force generated by turning a moving fluid. It acts at the centre of pressure of an object and is directed perpendicular to the flow direction — up in the case of a moving car.
Lift

Lift occurs when a moving flow of gas is turned by a solid object. The flow is turned in one direction and the lift is generated in the opposite direction. This can be derived from Newton's Third Law of Motion — to every action there is an equal but opposite reaction. Because air is a gas and the molecules are free to move about, any solid surface can deflect a flow.

Initial Design Ideas

Car Idea
This is one of our original sketches. We had the idea of a wedge-shape in our heads.

Car Idea
The designs became more complicated and intricate as we came up with more different ideas. The sketch above shows arcs being used for aerodynamics.

Car Idea


The image to the left was created to illustrate a possible design scheme for the car once it had been created. Black and red were suggested as colours.

Virtual Wind Tunnel Analysis

We tested our designs using SolidWorks Flow Simulation 2010. This allowed us to make small changes to the areas that mattered most as far as aerodynamics are concerned. The images below show the results of the Flow Simulation on our final chosen design for the National Finals.

Fluid Flow around Car
Side view of our final design


Fluid Flow around Car
Isometric view of our final design

Manufacturing

Our first car was manufactured at Cork Institute of Technology on Monday, February 22. The machine used was a Bridgeport 800 5-axis CNC milling machine, shown below.

Bridgeport 800

After not doing as well as we had hoped in the South Regional Final races, we came to the conclusion that we needed to make our car lighter — so we made a second car.

Fluid Hydrodynamic Bearings

Fluid Hydrodynamic Bearing

Spraying and Finishing

Our Resources Manager, Bryan, spray-painted our car. Gallahue's Garage, Anglesboro, generously sponsored three weeks of "training" for Bryan to learn how to professionaly paint the car.

A video of Bryan spraying the car can be found in the Video Galley.

Car - Top
Car - Top

Once the car was sprayed, the stickers — our logo, Gallahue's Garage, Sports4All, and the Formula 1 logo — were added.