Designing the dragster
Compressed Air Vehicles
Activity 5.1A – Dragster Design Lab
In this activity, you will work on the 3D model fabrication of a Dragster. You will then use the working drawings you create in the unit on Science of Technology.
It is important that you apply the basic principles of design and materials that you have learned in the prior lessons of this unit on Design and Modeling in order to solve problems. In this activity, you will need to apply problem-solving skills, group dynamics, and research, and to use your knowledge coupled with common sense to design and develop the 3D model of the vehicle. You will want to consider requirements, such as designing the vehicle so that it will travel a distance in the shortest amount of time when powered by compressed air as its fuel.
Computer with Inventor software
Part One: Designing the Dragster
First, you will need to read over the specifications and suggestions provided so that you are aware of the requirements (criteria and constraints), and you will need to complete the dragster specification worksheet.
Second, you will draw several sketches of your dragster ideas and use the design process to narrow down your choice.
SPECIFICATIONS AND REQUIREMENTS OF THE DRAGSTER
|1||The dragster will be constructed from a wedge of pine that is 1 1/2 inches thick x 12 inches long.|
|2||In the design process, you may reduce the length to 9 inches minimum.|
|3||The wedge is 3/4 inch high on the front end and 2 3/4 inches high at the other side.|
|4||On your sketch paper, you are to sketch (draw lightly in pencil so erasure is easy to do) three possible designs that you think would be both lightweight and aerodynamic. An aerodynamic dragster has smooth lines that resist friction from air.|
|5||After sketching three designs, choose the design idea you like the best and lightly sketch the outline for the side view in the wedge shaped space provided by your teacher. It is important to consider the design specifications at all times or your design will not meet the criteria and constraints.|
|6||Measure the total length of the car body and refer to the Design Specifications to confirm that your design conforms in size. If not, correct before continuing.|
|7||Locate places along the axle position line (this is the long horizontal line) where you will drill your axles. Be sure these are set back to the right of the vertical line for the front axle and to the left of the vertical line for the rear axle.|
|8||The design restrictions require that the dragster body be the full height and width of the original wood block at the point where the axles are located.|
|9||Correct the dragster design so that the outline for the body touches the top and bottom edges of the wedge block.|
|10||The specifications require that the height of the dragster body be at least 1/2 inch thick at all points between the axle locations|
|11||The axle centers for the wheels are located 1/2 inch above the bottom of the wood and the diameter of each hole is 9/64 of an inch.|
|12||Sketch the top view of your dragster. Again, be sure that your design uses the full width of the wood block at the axle locations.|
|13||The specifications require that the dragster is at least 3/8 inch wide at all points between the axles.|
SUGGESTIONS FOR IMPROVING PERFORMANCE OF YOUR DRAGSTER
Assuming the wheels are as friction free as possible, there are two things that will affect the performance or air racers – WEIGHT and AERODYNAMICS. Both factors are crucial for good performance.
A well-designed dragster will weigh less than 40 grams.
Designing the dragster with rounded corners and edges will greatly improve weight and aerodynamics.
When designing the dragster be sure the car slips off the air tube easily.
Part Two: Drawing the Dragster in Inventor
Now that you have your sketch approved, you will need to complete the following drawings in Inventor for this activity.
Isometric printout of the Dragster Body
Assembly Drawing of the Dragster (dragster with axles + wheels)
3D Model Fabrication of the Dragster in Inventor
When you create the design of the dragster in Inventor, all beginning steps will be the same for each dragster. Once the block has been extruded and holes drilled, all additional work you do in Inventor will depend on your own.
The following steps will lead you up to where you will add design features that will make your dragster uniquely yours.