CO2 Dragster Cars Mr. Kassel Technology Foundations Technology Education
Purpose of CO2 Activity • Understand how a CO2 car works • Design your CO2 car • Build your CO2 car • Race your CO2 car
Overview • Intro to Racing CO2 cars • Student examples • Engineering Principles • Designing your CO2 Car • Manufacturing your CO2 Car
Intro to Racing CO2 cars • 2 Cars are set up • Cars ride on guide wire from start of track to end of track • Co2 cartridge is punctured –propelling car forward • Two cars race • Cars go through end gate • light goes for fastest car • Race time is recorded for each car
What do you use for the track? • Many times when people are new to CO2 racing, they hear about cars running on a "track" and think that a track specially made for CO2 cars is needed to race them. • You can easily build a simple and inexpensive race track
CO2 Racetrack • The only track required is 50# test fishing line. • Fishing line is used as a guide line that the eye-hooks on the bottom of the cars attach to. • The fishing line runs between the start gate and the finish gate • We will likely run our races using only fishing line along the concrete floor of my lab. The smoother the surface, the faster the times will be.
length of the track • The length of the track is also important. You need to have at least 60 feet without any obstructions. Any shorter distance than this, and the cars will destroy themselves upon finishing a race. • The optimum track length is 66 feet (20 Meters), which is in scale with real dragstrip lengths of a quarter mile.
How fast are these things? • Up to 60 mph (100 kmh)
What is CO2? • Power is created by CO2 gas propulsion - CO2 gas is in the metal cartridges. • CO2 is the chemical abbreviation for Carbon Dioxide. Not to be confused with the poisonous Carbon Monoxide (CO) , • Carbon Dioxide is made up of two Oxygen atoms and one Carbon atom sharing electrons.
Engineering Principles The following Engineering Principles Relate to how and why a CO2 car works • Newton’s Laws of Motion • Mass • Drag • Friction
Newton’s 2nd Law of Motion • greater force = greater action. • Acceleration is dependent upon the mass and force of the car. F = ma • F = force • m = mass • a = acceleration • For a fast car, you need: • Big force • Light car
Mass • The Balancing Act: – Advantages: Cars with less mass go much faster. – Disadvantages: Cars with less mass are less stable and less durable. • Does takes more or less force to push 40g than it does to push 130g?
Acceleration • Acceleration is produced by the CO2 gas cylinder. • The CO2 canister produces thrust when you puncture it – propelling the CO2 car forward • It works similar to sticking a pin in a balloon - The balloon is propelled around the room by the thrust created by the escaping gas.
Forces of Resistance • Drag (from air resistance) (FW) • Friction
Drag Take a piece of wood, slap wheels on it, shoot it down a track at 60 MPH and the air rushing over the body and wheels will try to slow it down. • Scientifically this is called drag: the resistance of wind moving over an object.
Minimizing DRAG The Balancing Act: – Advantages: Aerodynamically shaped cars have less drag so they go faster. – Disadvantages: Aerodynamically "clean" cars are more difficult to build.
Friction Friction is a product of gravity • On a CO2 car, friction occurs primarily in three places: – between the wheels and the ground, – between the axles and the car body, – between the eye-hook and the fish line track.
Minimizing Friction • Make sure the axle & tires are free rotate. • Make sure the wheels are not rubbing on the car body. • Be sure to install your eye-hooks properly. Poorly aligned eye-hooks often the cause of a slow car.
What's the best design for a CO2 car? • Your Car must meet the size and dimensional requirements of TSA. • The best design is the one that wins. There is no "one design" that is best. • Generally, the two best indicators of a good car are clean aerodynamics and high craftsmanship. Often, really good designs that are built poorly will loose to so-so designs built well.
What is Design • 1.to intend for a definite purpose • 2.to form or conceive in the mind; • 3.to make drawings, preliminary sketches, or plans. • 4.to plan and fashion the form and structure of an object, work of art, etc. • 5.an outline, sketch, or plan, as of the form and structure of a work of art, or a machine • 6.the art of designing
Designing your CO2 car • Step 1: Fill out the design Brief • The client is you (it is your car) • The problem is? • The design statement explains what you are trying to design • The constraints are listed on the “overview and specifications” sheet *read this thoroughly before proceeding*
Design Statement • A Design Statement should be one of the first tasks undertaken in the design process • It should explain how you are going to solve your design problem (what you have to do to solve the problem). • The design statement is your vision – it should not be an afterthought merely to justify a pre-determined solution
Designing your CO2 car • Step 2 • Brainstorming (think about what you want your car to look like) • Sketch 6 different possible design ideas • Create detailed sketch
Designing your CO2 car • Step 3 • Complete technical drawing for CO2 car • You must have a high quality, accurate drawing • Drawing must be 1:1scale (actual size) • Drawing must be dimensioned (all dimensions must be in millimeters (mm) – note: 10mm =1cm)
Designing your CO2 car • Step 4 • Fill out list of the parts you will be using • Step 5 • Fill out plan of procedure (fill out using pencil, incase you need to change this later) • Step 6 • Get instructor to look over your drawings and activity booklet. • You must get instructor sign off before beginning to manufacture the car that you designed
Overview of the CO2 Car Manufacturing Process • http://co2.technologyeducator.com/cars/babybro.htm - Sample CO2 car being made • http://co2.technologyeducator.com/steps/steps4.htm - Step by step overview
Manufacturing your CO2 car • Step 7 - Create a template • Draw or trace the outline of your car on the graph paper. Attached it to the side and top of your basswood block - using clear or masking tape.
Manufacturing your CO2 car • Step 8 - drill the holes for the axles (using the drill press). • Make sure the axle holes are in the right spot and are straight • The holes should be perpendicular to the center line of the car and parallel with the bottom surface of the car. • * Take care to make sure these holes line up evenly and are drilled accurately. Crooked holes mean a slow car! Use a drill press and take your time! *
Manufacturing your CO2 car • Step 9 - Using the Bandsaw, cut out your shape. • When using the band saw to cut curves, you must use relief cuts (or you will break the band). • Follow the shape that is on the template that is taped to your CO2 car.
Manufacturing your CO2 car • Step 10 – Shaping and Sanding • Use a rasp or wood file ( you may also use the belt or spindle sander) for the initial sanding, in order to create desired roundness and curves • Hand Sand your CO2 car until you have reached the desired shape • Hand sand with fine sand paper to prepare the CO2 car for finishing.
Manufacturing your CO2 car • Step 11 – Finishing • Finish cars with wood stain, wood oil, varnish or spray paint. • Allow to dry and finish sand between coats.
Manufacturing your CO2 car • Step 12 – assembly • Assemble all the parts of the CO2 car • Wheels • Axels • Body • Eyelets • CO2 cartridge
CO2 Cars • If you need more info on the Design and Manufacturing Process check out: • http://co2.technologyeducator.com/steps/steps1.htm