Design and Manufacturing CO 2 Race Cars

Terms CO 2 : Carbon Dioxide Gas CO 2 : Carbon Dioxide Gas Mass: The bulk of an object Mass: The bulk of an object Drag: The resistance of wind moving over an object. Drag: The resistance of wind moving over an object. Friction: The resistance that one surface or object encounters when moving over another. Friction: The resistance that one surface or object encounters when moving over another. Newton's 3 rd Law: For every action, there is an equal and opposite reaction. Newton's 3 rd Law: For every action, there is an equal and opposite reaction.

CO 2 Cars: Introduction Everyone wants to design a CO 2 car that will scream down the track and leave their classmates in the dust, right? Well, designing a CO 2 car is like any other design challenge. In order to do well, you have to know what your doing, and this requires some homework and brainstorming on your part. It is important that you follow the design process or your car will not be constructed very well, giving your classmates the power to crush your car come race day. Making a super fast car involves learning about the principles behind CO 2 cars, the engineering factors involved, and the design envelope or constraints the project must remain within.

CO 2 Cars: Principles Most people will refer to CO 2 cars as dragsters. This invites the comparison to top fuel dragsters the likes of which are often seen (and heard) screaming down a drag strip at incredible speeds. And yes it's true that CO 2 cars are run two at a time in a race down a track just as those big thunderous top fuel dragsters are. But that's where the comparison ends. CO 2 powered cars run on the same principle that propels rocket or jet powered land speed record vehicles. One of these vehicles, Thrust SSC of the Thrusts SSC Team from England, recently broke the land-speed record as well as the sound barrier (over 760 MPH).

CO 2 Cars: Principles The driving principle behind these cars is that of Newton's Third Law: "For every action, there is an equal and opposite reaction.“ When the CO2 cartridge is punctured in the starting gate, the CO2 escapes with a great deal of force towards the rear of the car. And just as good Sir Newton would have predicted, the CO2 car reacts in the opposite direction with equal force rocketing down the track. Unlike a dragster engine that converts fuel into energy to drive a set of wheels, our CO2 race car is basically pushed by the CO2 cartridge.

CO 2 Cars: Principles Many of the features of a dragster will actually work against a CO 2 race car. For example, spoilers are used to force a dragster's wheels into the ground in an effort to increase traction so that all the engine's energy can be transformed into forward motion. Thanks to Newton's Third Law, the Co2 cartridge pushing our cars takes care of forward motion for us; spoilers, although cool looking, just add drag. Dragster engines burn enormous amounts of fuel which requires large air intakes and exhaust pipes to suck air into the engine and shoot hot exhaust gasses out of the engine. Our CO 2 race cars have no engine and burn no fuel, so air intakes and exhaust pipes only act like parachutes to slow them down.

CO 2 Cars: Principles Moral of the story: When one looks at the similarities between a CO 2 race car and land speed record vehicles (LSRV), then throw in knowledge of Newton's Third Law, it becomes clear that designs for CO 2 race cars should be styled after an LSRV, not as a dragster. Moral of the story: When one looks at the similarities between a CO 2 race car and land speed record vehicles (LSRV), then throw in knowledge of Newton's Third Law, it becomes clear that designs for CO 2 race cars should be styled after an LSRV, not as a dragster.

CO 2 Cars: 4 Engineering Principles Mass: Mass: Cars with less mass go much faster. Cars with less mass go much faster. Cars with less mass are less stable and less durable. Cars with less mass are less stable and less durable. Drag: Drag: Aerodynamically shaped cars are less "draggy," so they go faster. Aerodynamically "clean" cars are more difficult to build.

CO 2 Cars: 4 Engineering Principles Friction: Friction: A friction filled car is easy to build. A friction filled car is slow, so it tends to be more durable. A friction filled car is easy to build. A friction filled car is slow, so it tends to be more durable. Reducing friction takes a lot of extra effort, time and patience. Reducing friction takes a lot of extra effort, time and patience. Design Envelope Design Envelope Cars that follow a design envelope can compete equally and safely. Cars may go faster if a design envelope is not followed, but will be disqualified.

Design Envelope Specifications

CO 2 Car Types: Normal Cars Normal cars are built to race. Normal cars are built to race. Normal cars may use characteristics of other car styles. Normal cars may use characteristics of other car styles. Although the wheels are usually external, Normal Cars sometimes have internal front wheels. Although the wheels are usually external, Normal Cars sometimes have internal front wheels.

CO 2 Car Types: Normal Cars Pros: Pros: Totally reflects the skills, abilities and creativity of the designer/builder. Totally reflects the skills, abilities and creativity of the designer/builder. Always gets to race, and often does well at the school level. Always gets to race, and often does well at the school level. Can be built by the average student with average ability and normal tools. Can be built by the average student with average ability and normal tools. Doesn't require any special parts or materials. Doesn't require any special parts or materials. Cons: Cons: May or may not be competitive on a national level. May or may not be competitive on a national level.

CO 2 Car Types: Rail Cars A narrow "rail" that connects the front axle to the back of the car. A narrow "rail" that connects the front axle to the back of the car. Typically use external wheels Typically use external wheels The body of the car is usually lower to the ground in the front and middle and then rises up abruptly to hold the Co2 cartridge. The body of the car is usually lower to the ground in the front and middle and then rises up abruptly to hold the Co2 cartridge.

CO 2 Car Types: Rail Cars Pros: Pros: Easiest to build and design. Easiest to build and design. Thin rails reduce mass of the car, increasing speed. Thin rails reduce mass of the car, increasing speed. Can be built with normal wood working tools by most normal students. Can be built with normal wood working tools by most normal students. Cons: Cons: The thinner the rail, the greater chance of structural failure (breaking). The thinner the rail, the greater chance of structural failure (breaking). Exterior wheels are bad for aerodynamics. Exterior wheels are bad for aerodynamics. Body shape tends to encourage drag and hamper good aerodynamics. Body shape tends to encourage drag and hamper good aerodynamics.

CO 2 Car Types: Shell Cars Internal wheels. Internal wheels. Clean aerodynamic “bullet” shape. Clean aerodynamic “bullet” shape. Hollow underside forming a thin “shell” body. Hollow underside forming a thin “shell” body.

CO 2 Car Types: Shell Cars Pros: Pros: Very low drag aerodynamic shape. Very low drag aerodynamic shape. Hollow underside reduces weight. Hollow underside reduces weight. Usually capable of high speeds by design. Usually capable of high speeds by design. A great extension activity for gifted middle school students or pre-engineering students. A great extension activity for gifted middle school students or pre-engineering students. A perfect place for math and science activities on aerodynamics through wind tunnel use. A perfect place for math and science activities on aerodynamics through wind tunnel use. The highest use of technology when designed on CAD and created with a CNC. The highest use of technology when designed on CAD and created with a CNC.

CO 2 Car Types: Shell Cars Cons: Cons: Requires special wheels, axles and attachment clips - all non-stock parts that will add cost and friction. Requires special wheels, axles and attachment clips - all non-stock parts that will add cost and friction. More difficult to build, especially by hand; may be beyond the skill level of younger students. More difficult to build, especially by hand; may be beyond the skill level of younger students. Can be unstable, flips over easily. Can be unstable, flips over easily. Shell cars tend to all look similar reducing individual creative expression. Shell cars tend to all look similar reducing individual creative expression. Wheels and axles can cause friction very easily. Wheels and axles can cause friction very easily.

CO 2 Car Types: Transportation Modeling Cars Transportation modeling cars are recognizable as actual vehicles that one would see in real life. Transportation modeling cars are recognizable as actual vehicles that one would see in real life.

CO 2 Car Types: Transportation Modeling Cars Pros: Pros: A cool challenge to the design and build skills of their creators. A cool challenge to the design and build skills of their creators. Cons: Cons: TM cars, by design, often don't race. TM cars, by design, often don't race. When raced, due to their size and shape they may not achieve top speeds. When raced, due to their size and shape they may not achieve top speeds. Requires a high degree of modeling skill. Requires a high degree of modeling skill. Requires a higher skill level to build than other cars. Requires a higher skill level to build than other cars. Often uses special chrome parts, such as rims, that are an added expense. Often uses special chrome parts, such as rims, that are an added expense.

CO 2 Car Types: Show Cars Stunning design. Stunning design. High degree of creativity in the design. High degree of creativity in the design. Usually very intricate and delicate in their construction. Usually very intricate and delicate in their construction. Very showy paint jobs with glass like finishes. Very showy paint jobs with glass like finishes.

CO 2 Car Types: Show Cars Pros: Pros: Just plain cool to look at. Just plain cool to look at. An excellent way to develop visualization, design, and manufacturing skills. An excellent way to develop visualization, design, and manufacturing skills. Cons: Cons: Normally not made for racing. Normally not made for racing. Showy designs often flaunt structural weaknesses making them fragile. Showy designs often flaunt structural weaknesses making them fragile. Often uses special chrome parts, such as rims, that are an added expense. Often uses special chrome parts, such as rims, that are an added expense. Usually requires special tools such as a rotary sanding tool to create intricate details. Usually requires special tools such as a rotary sanding tool to create intricate details.

Manufacturing and Automotive Careers Mechanical Engineer Mechanical Engineer Electrical Engineer Electrical Engineer Automotive Engineer Automotive Engineer Auto Designer Auto Designer Auto Mechanic Auto Mechanic Auto Body and Paint Auto Body and Paint Race Car Driver / Pit Crew Race Car Driver / Pit Crew

CO2 Cars: Quiz

Grading Overall Car, 25 Points Total: The engineering principle of Mass has been considered The engineering principle of Friction has been considered The engineering principle of Drag has been considered Design involves advanced ideas, construction, or detail Design is thoughtful, not haphazard or block-like Body, 25 Points Total: Body meets design envelope Body is free of structurally weak areas Body shape is free of flaws

Grading Finish, 25 Points Total: Preparation for painting was done properly, smooth sanding Paint and finish is smooth and defect free Special details (multi-color, decals, special effects) are included Craftsmanship and Quality, 25 Points Total: Finished project maintains original design Attention to detail is evident Project was completed in a timely manner

Try to Beat This!!!!!