CO2 Car

Annie Douglas

1. Define the Problem

What need or want must be met by the solution?

Create a Dragster to win in a virtual race.

2. Brainstorming

In the space provided, sketch three possible solutions to the given problem. Remember to be creative!

One of my designs i made along the way to get to my goal, this was the first one with rounded sides i made.

This was my original design that looks like an ant but was a bit too heavy and did not work very well speed wise.

This green design was just another prototype that worked pretty well for a while

3. Research and Generating Ideas

In the space below, document your research. Be sure to include proper citations at the end of your notes.


  • The most common power plant used in land transportation vehicles is the internal combustion engine.
  • A four-stroke engine uses a piston and cylinder to draw fuel and air into the cylinder on its down or intake stroke. On the upstroke the air fuel mixture is compressed. At the top of this stroke, a spark ignites the fuel causing an explosion that forces the piston down, power stroke. When the piston comes back up the exhaust from the explosion is released.
  • A typical four-cylinder engine has a displacement of 1.8 liters and produces 140 hp.
  • A six-cylinder engine has displacement around 3.0 liters and produces about 200 hp.
  • Suspension connects the vehicle to the environment. For cars, it helps keep the rubber on the road. Suspension systems use control arms attached to the frame to allow wheels to move up and down.
  • Springs support the vehicle. Shocks are used to dampen the movement of the spring so the car does not bounce.
  • The guidance system provides information to the operator to help guide him/her to his/her destination.
  • The throttle system provides the driver with a mechanism to control the amount of air-fuel mixture that enters the combustion chamber. This control allows the operator to accelerate or decelerate the vehicle by increasing or decreasing air-fuel mixture
  • When a brake pedal is pressed, a hydraulic cylinder pushes fluid through lines to brake calipers. The calipers use hydraulic cylinders to push pads against a steel rotor to create friction. The friction caused by the pads clamping on the rotor slows down and stops the vehicle
  • The Ladder Chassis is made from two or more rails connected by a cross brace. It's like a ladder. This system was commonly used in automobiles through the 1970's. It is heavier than newer chassis designs and not as stiff.
  • The Tubular Space Frame is a light, stiff and safe chassis design. The frame uses steel tubes welded together with diagonal braces. Used in race cars.
  • The Unibody Chassis is made of sheet metal integrated into the design of the car. Sheet metal welded together forms tubes, beams, braces and other structural elements to make a system that is relatively light and stiff while protecting passengers
  • The support subsystem is not part of a land transportation vehicle.
  • The acceleration of an object of constant mass is proportional to the force acting upon it.
  • In mathematical form, the relationship of force, mass and acceleration is defined as:
  • An increase in force (F) will increase acceleration. Acceleration will also increase by decreasing mass (m).
  • The center of mass is a point. It has an x-coordinate and a y-coordinate, and both are important for different reasons. Its position from the ground (y-coordinate) affects the stability of the vehicle. Its position from the rear (x-coordinate) determines the distribution of mass between the front and rear axle assemblies.
  • Friction occurs when two surfaces are in contact and a force is moving one surface over the other
  • Friction is caused by the roughness of the two objects in contact. Even two materials that seem very smooth have some degree of roughness
  • Rolling friction is a force that resists the motion of wheels or balls. Rolling friction will slow your dragster but it is much less than sliding friction.
  • Drag occurs when a solid object moves through a gas or liquid.
  • When wind speed increases, the pressure increases. A vehicle moving through the air is like the wind pushing on your body
  • Streamlining involves changing the shape of an object to reduce pressure and friction caused by air flow
  • Frontal area is what the air stream sees or what you see looking at the front of a car.
  • The force from the cartridge (FC) is working to move the car forward. Drag (FD) and friction (FF) forces are working against this force. To maximize the net force, the equation tells us to increase the cartridge force and/or reduce the forces of drag and friction. Since we can't change the cartridge force, net force can only be increased by reducing all forms of drag and friction.


4. Identifying criteria and specifying constraints

What are the criteria and constraints?

Body  Tolerance  Minimum  Maximum  Length

202 mm

303 mm

Height with Wheels


73 mm

Width at Axles

36 mm

42 mm

Total width including wheels


88 mm

Mass (without CO2 cartridge)

43 g


Axles and Wheelbase  Tolerance  Minimum  Maximum  Number of Axles



Bottom of axle hole above car bottom

5 mm

8 mm

Rear axle hole from car rear

10 mm

98 mm

Wheelbase (measured at farthest point)

108 mm

268 mm

Space Washers



Axle Clips



Wheels  Tolerance  Minimum  Maximum  Front Diameter

31 mm

36 mm

Front Width

2 mm

5 mm

Rear Diameter

30 mm

40 mm

Rear Width

13 mm

18 mm

Power  Tolerance  Minimum  Maximum  Hole Depth

50 mm

52 mm

Wall Thickness

4 mm


Chamber Diameter

19 mm

20 mm

Lowest Point of Hole to Race Surface (with wheel/axle assembly)

28 mm

38 mm

5. Exploring possibilities

Reflect on your brainstorm ideas and research notes. Generate any additional designs which you feel meet the criteria and constraints in the space below.

6. Selecting an Approach

a. Enter the constraints of the project in the first column.

b. Score each sketch for each constraint. + = 3 pts., √=2 pts., - = 1 pt. c. Total the columns and circle the highest score.

Constraint              Sketch 1     Sketch 2     Sketch 3

Mass                       3                  1                  2

Width                      3                  1                  2

Wall Thickness       2                   3                  2

Length                    3                   3                 3

Total:                       11                 8                   9

7. Developing a Design Proposal

Take your highest scoring sketch and create working drawings (sketches with dimensions, so that you could build your project). Attach your working drawings to this sheet.

8. Making a model or prototype

In the space below, document (using digital pictures) your construction of the model/prototype. Be sure to include a picture of the final product.

9. Testing and Evaluating the Design, using specifications

As you create your solution, you will perform tests to make sure that the solution is meeting the needs of the given problem. If you solution does not work, you may need to repeat the previous steps of the Engineering Design Process, until you find a functional design. In the space below, document the type of test you conducted and the results.

Tests Performed: Raced against other cars in my class multiple times and was in the number one spot at one point.

10.Refining the Design

Based on your tests, propose refinements to the design and construction of the design problem in the space below.

My Final Product

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