CO2 Dragster Design

CO2 Dragster DesignCO2 Dragster Design

http://www.science-of-speed.com/science.asp

Research and DevelopmentResearch and DevelopmentObjectivesObjectives

Research in CO2 auto design involves the study Research in CO2 auto design involves the study of a few sciences related to the motion of your of a few sciences related to the motion of your dragster.dragster.

• AerodynamicsAerodynamics- the study of how solid objects displace fluid - the study of how solid objects displace fluid air and other gases;air and other gases;

• PhysicsPhysics- the study of matter in motion;- the study of matter in motion;

• TribologyTribology- the study of friction;- the study of friction;

Development of CO2 auto design requires-Development of CO2 auto design requires-

• Understanding the problem or purposeUnderstanding the problem or purpose- trying to achieve the - trying to achieve the fastest speed and/or best appearance;fastest speed and/or best appearance;

• Knowing your limitationsKnowing your limitations- being aware of safety regulations, - being aware of safety regulations, materials allowed, specifications, tolerances and materials allowed, specifications, tolerances and functionality;functionality;

• Making intelligent decisionsMaking intelligent decisions- taking what you learn and - taking what you learn and using it to your best advantage;using it to your best advantage;

• Testing your solutionTesting your solution- comparing results with your - comparing results with your classmates to see what works better;classmates to see what works better;

Research and DevelopmentResearch and DevelopmentObjectivesObjectives

Terms to Know- AerodynamicsTerms to Know- Aerodynamics

FluidFluid MassMass AerodynamicsAerodynamics DragDrag LiftLift Rear SuctionRear Suction Down ForceDown Force Frontal AreaFrontal Area

Aerodynamics in race cars Circle Track magazineAerodynamics in race cars Hot Rod Magazine

Research- AerodynamicsResearch- Aerodynamics

Air-Air-– Is a type of fluid such as water that can be Is a type of fluid such as water that can be

directed or displaced;directed or displaced;– Has mass and is measured in terms of pressure;Has mass and is measured in terms of pressure;– Applies direct and frictional forces to objects in Applies direct and frictional forces to objects in

motion;motion;


You should be aware of four aerodynamic You should be aware of four aerodynamic principles-principles-– DragDrag– Lift/Down ForceLift/Down Force– Drag CoefficientDrag Coefficient– Frontal AreaFrontal Area

http://www.hotrod.com/techarticles/body/hdrp_0609_aero_tricks_tips/


DragDrag is a combination of two forces that will is a combination of two forces that will work against the acceleration of your CO2 work against the acceleration of your CO2 car.car.– Frontal PressureFrontal Pressure occurs when tiny molecules of air hit the occurs when tiny molecules of air hit the

front of your car and is forced away to make room for front of your car and is forced away to make room for other molecules to hit it.other molecules to hit it.

– Rear SuctionRear Suction occurs when an empty pocket of air is occurs when an empty pocket of air is created in the back of your car resulting in a vacuum created in the back of your car resulting in a vacuum cleaner effect that tries to pull your car backward.cleaner effect that tries to pull your car backward.

Drag

• Aerodynamic force that resists the motion of an object moving through a fluid (air and water are both fluids).

•Try this next time you are in a car… put your hand out a window and rotate it. You will notice much more force (drag) when the palm of your hand is open and vertical then when it is open and horizontal

The amount of drag that your hand creates depends on a few factors, such as the size of your hand, the speed of the car and the density of the air. If you were to slow down, you would notice that the drag on your hand would decrease.

SuctionSuction

Notice that liquid is pushed up Notice that liquid is pushed up a straw when the balanced air a straw when the balanced air pressure is removed. The pressure is removed. The same effect happens to objects same effect happens to objects in motion. The air traveling in motion. The air traveling around the object can create a around the object can create a pocket of less air pressure pocket of less air pressure causing suction to occurcausing suction to occur

Air FlowAir FlowRear SuctionRear Suction


LiftLift is similar to rear suction in that a thin is similar to rear suction in that a thin empty pocket occurs as air passes over a flat empty pocket occurs as air passes over a flat surface causing the car to lift.surface causing the car to lift.

Down ForceDown Force is due to high pressure in curved is due to high pressure in curved surfaces that causes the car to be pushed surfaces that causes the car to be pushed down. down.

The Bernouli Effect:

•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.

In an airplane, when:Drag = Thrust & Weight = Lift

the plane will fly STRAIGHT & LEVEL

• If drag increases and/or thrust decreases the car will slow down

• Cars create thrust using engines. Your dragster will use a CO2 Cartridge

• In a race car (Indy or F1 style) the car is designed like an upside-down airplane wing which creates downforce rather than lift. This keeps the car on the ground and prevents lift-off.

• With cars, the principles of design are the same – which is to have the 4 aspects equal each other thus maximizing its aerodynamic efficiency.

•Airfoils or wings are also used in the front and rear of the car in an effort to generate more downforce. Downforce is necessary in maintaining high speeds through the corners and forces the car to the track. An Indy ground effect race car can reach speeds in excess of 230 mph using downforce. •In addition the shape of the underbody (an inverted wing) creates an area of low pressure between the bottom of the car and the racing surface. This sucks the car to road which results in higher cornering speeds.

The air moving under the car moves faster than that above it, creating downforce or negative lift on the car.

Because of the amount of downforce a race car creates, (in theory) if a race car is traveling at high enough speeds (+200kph) it could travel along a wall or even upside down on a road without falling!

Air FlowAir FlowLiftLiftDown ForceDown Force

Air Friction and LiftAir Friction and LiftWhen a ball rotates in motion, When a ball rotates in motion,

it causes the air around it to it causes the air around it to flow with the rotation, often flow with the rotation, often changing the direction with changing the direction with lift and down force.lift and down force.

The dimples in a golf ball are also used The dimples in a golf ball are also used

for reducing air friction with the surface.for reducing air friction with the surface.

But…read this -->But…read this -->Golf Ball Dimples & Drag


Drag CoefficientDrag Coefficient is a way of expressing how is a way of expressing how slippery a car is. slippery a car is.

Here is a tip to increase your speed and lower Here is a tip to increase your speed and lower your drag coefficient- your drag coefficient- (the more ways you can eliminate drag, turbulence, (the more ways you can eliminate drag, turbulence,

rear suction, lift and down force, the faster your rear suction, lift and down force, the faster your car will go)car will go)


Frontal AreaFrontal Area is the total of all surfaces in the front of your vehicle is the total of all surfaces in the front of your vehicle which cause drag.which cause drag.

Area = Length x WidthArea = Length x Width

ReviewReview

With one hand, which can be With one hand, which can be thrown further, a football . . .thrown further, a football . . .

or a soccer ball?or a soccer ball?

Review Tips- AerodynamicsReview Tips- Aerodynamics

Avoid flat upright surfaces in the front of Avoid flat upright surfaces in the front of your car to reduce turbulence.your car to reduce turbulence.

Avoid flat upright surfaces in the back of Avoid flat upright surfaces in the back of your car to reduce rear suction.your car to reduce rear suction.

Shield as much air at the bottom of your car Shield as much air at the bottom of your car to maintain traction.to maintain traction.

Keep the surface area exposed to Keep the surface area exposed to oncoming air to a minimum.oncoming air to a minimum.

Terms to Know- PhysicsTerms to Know- Physics

ForceForce AccelerationAcceleration

Research- PhysicsResearch- Physics

Force = Mass x AccelerationForce = Mass x AccelerationHeavier objects require more effort to move at the same Heavier objects require more effort to move at the same

speed;speed;

It is easier to push a CO2 car out of the ditch than to push an It is easier to push a CO2 car out of the ditch than to push an actual car out of the ditch.actual car out of the ditch.

Everyone’s force on the CO2 car will be the same. The less Everyone’s force on the CO2 car will be the same. The less mass, the greater the accelerationmass, the greater the acceleration

Research PhysicsResearch PhysicsHeavy Mountain BikeHeavy Mountain Bike•DurableDurable•For Rough TerrainFor Rough Terrain•Requires more EnergyRequires more Energy

Light Racing BikeLight Racing Bike•FastFast•For Long DistanceFor Long Distance•Requires less EnergyRequires less Energy

Research- PhysicsResearch- PhysicsHow does the angle of your CO2 cartridge How does the angle of your CO2 cartridge

affect the efficiency of your car? affect the efficiency of your car?

Review Tips- PhysicsReview Tips- Physics

Avoid unnecessary extensions and ornaments that add Avoid unnecessary extensions and ornaments that add weight to your car.weight to your car.

The lighter you design your car, the more power will be The lighter you design your car, the more power will be used out of your CO2 cartridge.used out of your CO2 cartridge.

Make sure that your drill holes are straight and accurate to Make sure that your drill holes are straight and accurate to reduce extra forces acting on your car.reduce extra forces acting on your car.

Research- TribologyResearch- TribologyTribologyTribology is the study of friction between solid surfaces. is the study of friction between solid surfaces.

Friction is a force that resists movement.Friction is a force that resists movement. Friction is found between moving parts and surfaces.Friction is found between moving parts and surfaces. Without friction, objects would never come to rest.Without friction, objects would never come to rest.

Where will you find friction forces acting on Where will you find friction forces acting on your car?your car?

Research- TribologyResearch- Tribology

How many wheels should you have and why?How many wheels should you have and why?

Research- TribolobyResearch- Triboloby

Does the paint job affect your car: Why or why not?Does the paint job affect your car: Why or why not?

Research PhysicsResearch PhysicsHeavy Mountain BikeHeavy Mountain Bike

•Wider Ground ContactWider Ground Contact•More Surface FrictionMore Surface Friction

Light Racing BikeLight Racing Bike•Narrower Ground ContactNarrower Ground Contact•Less Surface FrictionLess Surface Friction

Review Tips- TribologyReview Tips- Tribology

Painting your car will reduce aerodynamic Painting your car will reduce aerodynamic friction.friction.

Axel design is important to reducing friction.Axel design is important to reducing friction. Lubrication of the axels can reduce friction.Lubrication of the axels can reduce friction. Less ground contact wheels have with the Less ground contact wheels have with the

ground, the less friction will be present.ground, the less friction will be present.

Review Tips- AerodynamicsReview Tips- Aerodynamics

Avoid flat upright surfaces in the front of Avoid flat upright surfaces in the front of your car to reduce turbulence.your car to reduce turbulence.

Avoid flat upright surfaces in the back of Avoid flat upright surfaces in the back of your car to reduce rear suction.your car to reduce rear suction.

Shield as much air at the bottom of your car Shield as much air at the bottom of your car to maintain traction.to maintain traction.

Keep the surface area exposed to Keep the surface area exposed to oncoming air to a minimum.oncoming air to a minimum.

Review Tips- PhysicsReview Tips- Physics

Avoid unnecessary extensions and ornaments that add Avoid unnecessary extensions and ornaments that add weight to your car.weight to your car.

The lighter you design your car, the more power will be The lighter you design your car, the more power will be used out of your CO2 cartridge.used out of your CO2 cartridge.

Make sure that your drill holes are straight and accurate to Make sure that your drill holes are straight and accurate to reduce extra forces acting on your car.reduce extra forces acting on your car.

Review Tips- TribologyReview Tips- Tribology

Painting your car will reduce aerodynamic Painting your car will reduce aerodynamic friction.friction.

Axel design is important to reducing friction.Axel design is important to reducing friction. Lubrication of the axels can reduce friction.Lubrication of the axels can reduce friction. Less ground contact wheels have with the Less ground contact wheels have with the

ground, the less friction will be present.ground, the less friction will be present.

Documents

CO2 Dragster Design