1. CO2 Dragster Design

2. Research and Development Objectives
Research in CO2 auto design involves the study of a few sciences related to the motion of your dragster.
Aerodynamics- the study of how solid objects displace fluid air and other gases;
Physics- the study of matter in motion;
Tribology- the study of friction;

3. Research and Development Objectives
Development of CO2 auto design requires-
Understanding the problem or purpose- trying to achieve the fastest speed and/or best appearance;
Knowing your limitations- being aware of safety regulations, materials allowed, specifications, tolerances and functionality;
Making intelligent decisions- taking what you learn and using it to your best advantage;
Testing your solution- comparing results with your classmates to see what works better;

4. Terms to Know- Aerodynamics
Fluid
Mass
Aerodynamics
Drag
Lift
Rear Suction
Down Force
Frontal Area

5. Research- Aerodynamics
Air-
Is a type of fluid such as water that can be directed or displaced;
Has mass and is measured in terms of pressure;
Applies direct and frictional forces to objects in motion;

6. Research- Aerodynamics
You should be aware of four aerodynamic principles-
Drag
Lift/Down Force
Drag Coefficient
Frontal Area

7. Research- Aerodynamics
Drag is a combination of two forces that will work against the acceleration of your CO2 car.
Frontal Pressure occurs when tiny molecules of air hit the front of your car and is forced away to make room for other molecules to hit it.
Rear Suction occurs when an empty pocket of air is created in the back of your car resulting in a vacuum cleaner effect that tries to pull your car backward.

8. Air Flow
Rear Suction

9. More Science on Suction
Since we know that air has mass with weight measured in pressure, we take notice that liquid is pushed up a straw when the balanced air pressure is removed. When fluid air is removed from a surface around your car, air pressure causes the empty space to be filled in by the weight of the atmosphere.

10. Research- Aerodynamics
Lift is similar to rear suction in that a thin empty pocket occurs as air passes over a flat surface causing the car to lift.
Down Force is due to high pressure in curved surfaces that causes the car to be pushed down. (Up next, notice how the windshield takes the shape of a spoiler.)

11. Air Flow
Lift
Down Force

12. Air Friction and Lift
When a ball rotates in motion, it causes the air around it to flow with the rotation, often changing the direction with lift and down force.
The dimples in a golf ball are also used for reducing air friction with the surface.

13. Research- Aerodynamics
Drag Coefficient is a way of expressing how slippery a car is.
Here is a tip to increase your speed and lower your drag coefficient-
(the more ways you can eliminate drag, turbulence, rear suction, lift and down force, the faster your car will go)

14. Research- Aerodynamics
Frontal Area is the total of all surfaces in the front of your vehicle which cause drag.
Area = Length x Width

15. Review With one hand, which can be thrown further, a football . . .
or a soccer ball?

16. Review Tips- Aerodynamics
Avoid flat upright surfaces in the front of your car to reduce turbulence.
Avoid flat upright surfaces in the back of your car to reduce rear suction.
Shield as much air at the bottom of your car to maintain traction.
Keep the surface area exposed to oncoming air to a minimum.

17. Research- Physics (Preview)
Which ball can I hit farther, a base ball or a softball?
how about a golf ball?

18. Terms to Know- Physics
Force
Acceleration

19. Force = Mass x Acceleration
Research- Physics
Force = Mass x Acceleration
Heavier objects require more effort to move at the same speed;
It is easier to push a CO2 car out of the ditch than to push an actual car out of the ditch.

20. Research Physics Heavy Mountain Bike Durable For Rough Terrain
Requires more Energy
Light Racing Bike
Fast
For Long Distance
Requires less Energy

21. Research- Physics
How does the angle of your CO2 cartridge affect the efficiency of your car?

22. Review Tips- Physics
Avoid unnecessary extensions and ornaments that add weight to your car.
The lighter you design your car, the more power will be used out of your CO2 cartridge.
Make sure that your drill holes are straight and accurate to reduce extra forces acting on your car.

23. Research- Tribology
Tribology is the study of friction between solid surfaces.
Friction is a force that resists movement.
Friction is found between moving parts and surfaces.
Without friction, objects would never come to rest.
Where will you find friction forces acting on your car?

24. Research- Tribology
How many wheels should you have and why?

25. Research- Triboloby
Does the paint job affect your car: Why or why not?

26. Research Physics Heavy Mountain Bike Wider Ground Contact
More Surface Friction
Light Racing Bike
Narrower Ground Contact
Less Surface Friction

27. Review Tips- Tribology
Painting your car will reduce aerodynamic friction.
Axel design is important to reducing friction.
Lubrication of the axels can reduce friction.
Less ground contact wheels have with the ground, the less friction will be present.

28. Review Tips- Aerodynamics
Avoid flat upright surfaces in the front of your car to reduce turbulence.
Avoid flat upright surfaces in the back of your car to reduce rear suction.
Shield as much air at the bottom of your car to maintain traction.
Keep the surface area exposed to oncoming air to a minimum.

29. Review Tips- Physics
Avoid unnecessary extensions and ornaments that add weight to your car.
The lighter you design your car, the more power will be used out of your CO2 cartridge.
Make sure that your drill holes are straight and accurate to reduce extra forces acting on your car.

30. Review Tips- Painting your car will reduce aerodynamic friction.
Axle design is important to reducing friction.
Less ground contact wheels have with the ground, the less friction will be present.

31. Wisconsin Applicable Teaching Standards
By the end of 8th grade, students will be able to:
A.8.1 Show that technology has allowed us to further the efforts of science and, in
turn, science has enabled us to develop better technology
A.8.2 Explain the need for and application of knowledge and skills from other
disciplines when engaging in technological activities
A.8.3 Identify and contrast the connections and differences between technology and
other disciplines
A.8.4 Determine that technological knowledge is valuable but not always available to
everyone on an equal basis
A.8.7 Discover that human will or desire can lead to the design of new technology in
order to seize an opportunity or solve a problem