Air Powered Dragster Introduction An important consideration in designing a vehicle is aerodynamics

The aerodynamics of a vehicle can be tested with the aid of a wind tunnel. In a wind tunnel, we can observe and measure the effects of the air stream on the vehicle. The flow of air moving around a vehicle is called streamline. A body with an overall rounded or square shape will cause air to break away from the streamline into swirls of air. This uneven or turbulent air movement that will slow the vehicle down is called drag. Vehicles have less resistance if they are rounded in the front and tapered off to a point in the rear (teardrop shape).

In this activity, you will design, construct, and test an aerodynamically sound vehicle. The car you will be building is like a miniature air powered dragster. As you build your dragster, take your time. It will have a better chance of looking good and going fast if you build it with patience and care. One major mistake can ruin the whole dragster and disqualify you from racing. Take pride in your work and try to make the best dragster in the class.
Engineering Design Challenge
You are an automotive design engineer in the research and development department of the Rattler Automotive Company. You have been assigned the task of designing the new, fuel-efficient, aerodynamically sound, stylish, and futuristic automobile for the company. You will be in charge of the designing, constructing, and testing of the new vehicle. All cars in the company will be compared for excellence in design, craftsmanship, aerodynamics, and the fastest racing time.
Materials/Supplies
- 1/4” graph paper - masking tape -sandpaper

- soda straw - 2 axles - 2 front wheels

- 5/8” x 2-3/4” x 12” basswood block - 2 rear wheels


Specifications

1. 
   The car must be at least 9-3/4” long. The block is 9-15/16”” to start so you have little room to sand the front and/or back ends.
   
2. 
   At the point that the axles pass through the car, the car must remain the full width of the block (1-1/8” wide).
   
3. 
   The minimum wheel base is 5” and the maximum is 7-1/2”.
   
4. 
   You cannot cut into the engine compartment in any way.
   
5. 
   The car body must be at least 3/8” thick at all points between the axle locations.
   

2. Look over the thumbnails and choose the best idea(s). Sketch this best idea a little larger, with more detail, and from several angles or views (rough sketch).

3. Very neatly draw your dragster exact size and detail on the preprinted block templates. These templates will be used as the pattern to cut out your dragster. Be sure to show the location of the axle holes. Use a pencil so that you can easily make changes if necessary.

4. Check to see that your templates meet ALL specifications – total car length, wheel base, etc.)

5. Take your thumbnails, rough sketch, and templates to the teacher to have them approved. (Teacher Signature: _________________________________ )

6. Carefully cut out the top and side views of your car from the graph paper.

7. Tape the templates on your Styrofoam block and trace around them with a felt-tip pen. (Note: Tape the top view template to the bottom of the Styrofoam block.

8. Using the hot wire Styrofoam cutter cut the side view of your car. Be careful. The Styrofoam will break very easily.

9. Cut the shapes drawn on the bottom of the piece next.

10. Shape your vehicle using files and sandpaper.

11. Test your Styrofoam mock-up in the wind tunnel and modify it if necessary.

12. Take your Styrofoam mock-up or prototype to the teacher for approval.

(Teacher Signature: __________________________________ )

13. Tape the templates on your wooden block and trace around them with a pencil. Be sure to locate and mark the axle holes and engine housing. (Note: Tape the top view template to the bottom of the wooden block.

14. Drill the axle holes (11/64”) on the drill press being very careful to keep them straight and parallel to each other. They should be 1/4” from the bottom of the car.

15. Shape the side view first. Then, shape the top view which you traced on the bottom of the block. Be very careful not to cut into the engine housing.

16. Finish smoothing the car using finer and finer grit sandpaper

17. Test your vehicle in the wind tunnel and modify it if necessary.

19. Take your car home an apply spray paint and/or decals (optional).

20. Cut two pieces of soda straw 1-1/8” long for bearings. Insert one straw through the front axle hole and the other through the rear axle hole.

21. Insert axles through the straws.

22. Carefully place the wheels on the axles. Be careful not to break the wheels. If the wheel does not stay on place a drop of hot-melt glue in the wheel before placing it on the axle.

23. Your dragster is now ready to test. You may test it in the wind tunnel again and roll it down an inclined ramp to test that it rolls straight and has little friction.

- sketches (3 thumbnail sketches/1 rough sketch/templates) 5 pts

- Styrofoam mock-up 5 pts

- LSRAV dragster

- design (creativity/appearance) 10 pts

- workmanship (shaping/smoothing/finishing) 10 pts

- aerodynamic design (wind tunnel results) 10 pts

- performance (speed) 10 pts

1st place = 10 pts

2nd place = 9 pts

3^rd & 4^th place = 8 pts

5th-8th = 7 pts

9th-16th = 6 pts

17th-32nd = 5 pts

All Others = 4 pts

2. In addition, winners of each of the following will receive additional points:
- Most Creative (as voted by class) 5 pts

- Best Built (as voted by class) 5 pts

- Most Aerodynamic (lowest drag in wind tunnel) 5 pts

- Fastest Dragster 5 pts