Science of Speed Unit 2

Design for Speed

Student Workbook Student Designer/Engineer: __________________________________________________________________________ Teacher: _________________________________________________________________ Class Period: ______________

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Written by Brad Blue and Cody White.

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Table of Contents Design for Speed

Part 1 Dragster Design Checklist: Dream, Design, Build, Test, Race..................................................................................................1 “Engineering Design Process” resource page...............................................................................................................................3 Phase 1: Design: Graphics and Layout............................................................................................................................................6 “Thumbnail Drawing Sheet”...............................................................................................................................................................9 Phase 2: Go/No Go: Checking Specifications............................................................................................................................ 11 “Design Specifications” data sheet................................................................................................................................................ 13 “Using the Go/No Go Gauge” resource page............................................................................................................................. 15 Phase 3: Prototyping, Part 1............................................................................................................................................................. 17 Phase 4: Go/No Go: Prototyping, Part 2...................................................................................................................................... 18 “Prototype Evaluation” worksheet................................................................................................................................................. 21 Phase 5: Car Construction – From Prototype to Model......................................................................................................... 23 Phase 6: Go/No Go: Collect Data – Meaningful Measurements......................................................................................... 25 “Car Specifications” data sheet....................................................................................................................................................... 27 “Meaningful Measurements” data sheet..................................................................................................................................... 29 Part 2 Phase 8: Crunching the Numbers.................................................................................................................................................. 32 “Need for Speed” data sheet........................................................................................................................................................... 33 Phase 9: Analyze Data – Interpretation....................................................................................................................................... 37 Phase 10: Propose and Make Modifications.............................................................................................................................. 38 “Proposed Changes” worksheet..................................................................................................................................................... 39 Phase 11: Go/No Go: Design Modifications and Detail......................................................................................................... 41 Phase 14: Collect Data....................................................................................................................................................................... 42 “Final Results” worksheet.................................................................................................................................................................. 43 Glossary................................................................................................................................................................................................... 45

Design for Speed Part 1

Dragster Design Checklist

Student Designer/Engineer: _______________________________ Teacher: _______________________________________________ Date: ________________________ Car Name: _________________

Dream, Design, Build, Test, Race ❑❑ ❑❑ ❑❑ ❑❑ ❑❑ ❑❑ ❑❑ ❑❑ ❑❑ ❑❑ ❑❑ ❑❑ ❑❑ ❑❑

Phase 1: Design: Graphics and Layout Phase 2: Go/No Go: Checking Specifications Phase 3: Prototyping, Part 1 Phase 4: Go/No Go: Prototyping, Part 2 Phase 5: Car Construction – From Prototype to Model Phase 6: Go/No Go: Collect Data – Meaningful Measurements Phase 7: Trial Races – Performance Phase 8: Crunching the Numbers Phase 9: Analyze Data – Interpretation Phase 10: Propose and Make Modifications Phase 11: Go/No Go: Design Modification and Detail Phase 12: Design and Aesthetic Judging Phase 13: A Day at the Races – Performance Phase 14: Collect Data

1

Engineering Design Process

1

Determine the problem or the opportunity (idea).

3

Design is complete.

F

Redesign or improve the solution.

2

Determine the specifications.

E

Test and analyze the solution.

A

Research.

B

D

Brainstorm possible solutions.

Prototype or model the solution.

C

Formulate a solution to implement.

3

Engineering Design Process The process of engineering design is the road map to converting an idea into reality. It provides the steps that are necessary for success and helps keep those who are involved on track.

The process involves nine basic steps, many of which may be repeated. This repetition makes up the looping part of the process. The illustration shows how the process takes place.

1. Determine the problem or opportunity (idea).

Have you ever heard the expression “Necessity is the mother of invention”? That means that new creations and inventions often are made to fill a specific need. For engineers looking to create a product, it really pays to think about the need they are seeking to serve. The more clearly their goals are defined, the more their creation can be true to those goals. In the case of a CO2 dragster, for example, one engineer might decide that super speed is the number one goal. But another engineer might decide that a cool look is ultimately what is most important in their design. Knowing this guides the engineers when they make decisions about the design of their dragsters.

2. Determine specifications.

When the problem is understood, it is time to get down to the finer details. Specifications tell an engineer in very specific terms what is needed. Often these specifications are in the form of numbers or measurements. A weight range that a product must fall within, measurements for specific parts of the design, or how fast something must move are all common types of specifications an engineer may face. In the Science of Speed, a list of specifications has been provided for you. Your design must meet these specifications. (You can only move forward from Go/No Go points when your design meets them.)

The Design Loop: The following steps may be repeated a number of times to reach a solution. Each cycle through the loop is called an iteration.

A – Research.

Research is an organized study of the problem or idea. It might include looking at what other engineers have done to address similar problems, properties of materials, science principles, facts, and theories. An automotive engineer would not think of designing a car completely from scratch. He or she would draw inspiration from existing designs while also trying to make them unique.

B – Brainstorm possible solutions.

Brainstorming usually involves coming up with numerous ideas before settling on one. The ideas don’t have to all be brilliant – or even good. The point is to kick-start the imagination so that innovative solutions can be discovered. When you are brainstorming, one idea often leads to another.

C – Formulate a solution to implement.

From the brainstorming session, select a single method to solve the problem. The method (or solution) should begin to take form through written descriptions, sketches, outlined procedures, and a list of needed materials.

D – Prototype or model the solution.

Construct a model, which is also called a prototype. Depending on the problem, the model might be full size or a scale model. The model might also be a working model; a critical portion of the model may incorporate a working part; or it might just be a model to determine size, fit, or compatibility. The model is intended to provide feedback (positive or negative) regarding the proposed solution.

4

Engineering Design Process E – Test and analyze the solution.

Test the solution, which in most cases is the model, in an appropriate fashion to determine durability, ease of use, adherence to specifications, functionality (if it does what it is supposed to do), and other characteristics. These results of the test are recorded as both observations and data. To analyze results, look at them in a way that helps you see the observations and data in an organized fashion. This could be an essay, a graph, or an image. Engineers must think carefully to be sure they aren’t misinterpreting their data. Approach the data with an open mind and a willingness to challenge your assumptions.

F – Redesign or improve the solution.

From the testing and analysis process – and from deciding a time frame for completing the design – a decision is made to do one of the following: • Accept the proposed and modeled solution as the final product.

• Attempt to redesign or improve the solution. If this decision is made, then an additional iteration (going through the design loop again) is completed. When you are finished working through the second iteration, the solution is tested and analyzed, and again the decision whether to do another iteration is made. If not, this is the final solution.

• Stop the design process without a successful solution. Sometimes, there are instances in which a practical solution cannot be found – at least not within the given time frame, with the materials and equipment available, or with a solution that satisfies all the specifications determined in the beginning.

For some projects, numerous iterations are done to find a satisfactory solution.

3. Design is complete.

The design process is complete when the choice is made to use a final design. At this point, the design process exits the design loop and goes to an implementation stage where the product or idea is put to use. It is likely that more challenges will arise when an idea or product is implemented. At that point, the engineering design process can be used again to determine the best way forward.

5

Student Instruction Phase 1 Design: Graphics and Layout QuickView Review car designs you like and draw multiple thumbnail sketches to generate ideas for your own car. After creating at least three designs, select one and do a more detailed multiview drawing.

Materials “Thumbnail Drawing Sheet” “Multiview Design Sheet”

Engineering Design Process 1. Determine the problem or the opportunity (idea).

2. Determine the specifications.

The Design Loop A. Research.

B. Brainstorm possible solutions.

C. Formulate a solution to implement.

Procedure 1. Look through the collection of vehicle photos, both the real-world cars and the CO2 dragsters. You will notice that many CO2 cars are inspired by features of real cars but that they have a form all their own. Pick out several photos of cars that you like.

2. Sketch at least three car designs on your “Thumbnail Drawing Sheet.” You can sketch more than three if you like. Each design should have a top, side, and isometric drawing. The designs you make do not need to look exactly like the cars in your chosen photos. In fact, they do not need to look like them at all. The photos are only for inspiration and ideas. The drawings you are making are only quick sketches. The point is to capture an idea, not to make a polished, perfect drawing (Figure 1).

3. After you have drawn three thumbnail sketches, decide whether you like any of these well enough to use it as a final design. If not, keep making more sketches. If one is close to being satisfactory but not quite where you want it to be, make another sketch of that design but with modifications that make it to your liking. Do not just erase sketches you have already made. Instead, create new sketches. Stop when you have at least three sketches and one that you really like.

4. When you have created all your thumbnail sketches, choose the one that you like the most. Study it and imagine how it will look from the side, from the top, from the front, and from the back.

6

Top

Side

Isometric

(Figure 1)

Student Instruction 5. You will now transform your sketch into a series of detailed full-size drawings. Fill out the information at the top of the “Multiview Design Sheet.” For Design Number, write the numeral 1. If you do another detailed drawing later, you will redraw it on another sheet with your changes and keep track of the number of designs you’ve made.

6. You will do a side-view and a top-view drawing. Before you begin drawing, however, look at the specifications indicated on the “Multiview Design Sheet.” These tell you such things as how long or short the car may be and how far apart the wheels may be. When you make your drawings, make sure that you follow these specifications.

7. Make a detailed side-view drawing of this sketch on the “Multiview Design Sheet.” You will make your drawing full scale, which means that your drawing will be the same size that you want your car to be. If your car will be 220 millimeters inches from front to back, so will your drawing. When making a side-view drawing, show only the side. You should not show any of the top, bottom, back, or front. Include the placement of the screw eyes on this drawing. (These should not be placed below the axles.)

8. Make a top-view drawing on the “Multiview Design Sheet.” Just as before, the drawing will be at full scale.

Show only the top of the vehicle. To do this, imagine that you are standing directly over your vehicle and looking down at it. Use the graph lines to make sure that the two drawings are aligned.

9. If time remains, you may also draw a front-view drawing and a back-view drawing. You may also add details to your car such as decals and painting ideas.

10. Save all your work in your portfolio.

7

Thumbnail Drawing Sheet

Student Designer/Engineer: _______________________________ Teacher: _______________________________________________ Date: ________________________ Car Name: _________________

9

1

Top

Side

Isometric

2

Top

Side

Isometric

3

Top

Side

Isometric

Student Instruction Phase 2 Go/No Go: Checking Specifications QuickView Use the Go/No Go Gauge to ensure your multiview drawings meet the specifications. If not, adjust your drawings as needed.

Materials “Design Specifications” data sheet “Using the Go/No Go Gauge” data sheet “Multiview Design Sheet”

Engineering Design Process C – Formulate a solution to implement.

Procedure 1. On the “Design Specifications” data sheet, find the first column of blank boxes. Write “Design #1” in the top space of this column.

2. Look carefully at the Go/No Go Gauge to find all the measurements that are listed on the “Design Specifications” data sheet. Each of these is written as a range. For example, the full body length of your car design may not be more than 305 millimeters, but it must also be at least 200 millimeters. Consult the “Using the Go/No Go Gauge” data sheet for clarification as needed.

3. Using the Go/No Go Gauge, measure each aspect of the car that is listed on the “Design Specifications” data sheet. Lay the gauge directly down onto your “Multiview Design Sheet” and measure your drawing. Fill in your measurements in the appropriate spaces in the column that you have labeled “Design #1.” (Leave the two bottom spaces in the column blank as they don’t apply to the design drawing.)

4. Compare each measurement to its appropriate acceptable range.

5. Are any of your measurements outside of the acceptable range? If so, you will need to create a new drawing using a new “Multiview Design Sheet.” For example, if the car needs to be taller, redraw your drawing, but make the car taller. Sometimes, in changing one thing, you find that you are no longer satisfied with your car’s design. You might have to change other aspects of your design as well. If you make a second design, write a number 2 in the Design Number line.

6. If all your measurements were within the acceptable ranges and you made no changes, you are done. If you made changes, however, you must now remeasure each aspect of your design using the Go/No Go Gauge.

Record the new measurements in the next column on the “Design Specifications” data sheet. Label the column “Design #2.” (Leave the two bottom spaces in the column blank as they don’t apply to the design drawing.)

7. Compare each measurement to its appropriate specification range. If all your measurements are within the acceptable ranges and you made no changes, you are done. If any measurements are still not within range, continue to rework your design until all the specifications are met.

11

Student Instruction 8. When you are satisfied with your drawing and all the measurements fall within the acceptable ranges, present them to your teacher for final approval.

9. Save all your work in your portfolio.

12

Design Specifications

Student Designer/Engineer: _______________________________ Teacher: _______________________________________________ Date: ________________________ Car Name: _________________

Acceptable Ranges

13

Car length

200 mm-305 mm

Wheelbase

105 mm-270 mm

Distance between screw eyes

155 mm-270 mm

Body width – front axle

35 mm-42 mm

Body width – rear axle

35 mm-42 mm

Front axle length

42 mm-70 mm

Rear axle length

42 mm-70 mm

Rear axle hole from rear of wooden block

9 mm-100 mm

Bottom of front axle hole above bottom of wooden block

5 mm-10 mm

Bottom of rear axle hole above bottom of wooden block

5 mm-10 mm

Height of cartridge hole from bottom of wooden block to hole center

31 mm-35 mm

Clearance around cartridge hole

3 mm minimum

Teacher Signature: __________________________________________ Check one: ____ Go ____ No Go

Using the Go/No Go Gauge To measure with the Go/No Go Gauge, hold it directly up to your car or design drawing. Some parts of the car are made to be measured with specific parts of the gauge. Other parts are measured with the metric ruler on the back of the gauge. The gauge lists more specifications than you are required to use in the Science of Speed. This sheet shows you which specifications to check, which parts of the gauge to consult, and which areas of your car to measure.

Acceptable Ranges

Letter on Diagrams

Car length

200 mm-305 mm

A

Wheelbase

105 mm-270 mm

B

Distance between screw eyes

155 mm-270 mm

C

Body width – front axle

35 mm-42 mm

D

Body width – rear axle

35 mm-42 mm

E

Front axle length

42 mm-70 mm

F

Rear axle length

42 mm-70 mm

G

Rear axle hole from rear of wooden block

9 mm-100 mm

H

Bottom of front axle hole above bottom of wooden block

5 mm-10 mm

I

Bottom of rear axle hole above bottom of wooden block

5 mm-10 mm

J

Height of cartridge hole from bottom of wooden block to hole center

31 mm-35 mm

K

Clearance around cartridge hole

3 mm minimum

L

D, E L C A 15 H

B, F, G, H, I, J, K

GE

L

DF

B

K J C A

I

Student Instruction Phase 3 Prototyping, Part 1 QuickView Create a polystyrene prototype based on your design.

Materials Polystyrene blank Copy of your “Multiview Design Sheet” Marker Cutting tool Fine sandpaper or knife Masking tape

Engineering Design Process D – Prototype or model the solution.

Procedure 1. Gather a printout or photocopy of your most up-to-date full-scale design. Do not destroy your original drawing. That must be kept for your portfolio.

2. Cut out the top and side views from the design.

3. Tape the side view to the polystyrene blank.

4. Using the marker, outline the side view onto the polystyrene blank.

5. Remove the side view.

6. Tape the top view to the polystyrene blank. Make sure the edges of the drawing are aligned with the side view.

7. Outline the top view onto the polystyrene blank.

8. Remove the top view.

9. You will now cut out the design from the blank. First, cut out along the side view. When you cut through the blank along the line, waste pieces will fall off. Keep these. You will need them shortly.

10. Gather the waste pieces and fit them back onto the working piece. Now, use two bands of masking tape around the assembly to secure the pieces together.

11. Cut out the top view.

12. Now, you can throw away the waste pieces and masking tape.

13. Smooth the corners of your prototype.

14. Use a marker to identify the axle location, but do not drill it.

15. Write your name on your prototype.

17

Student Instruction Phase 4 Go/No Go: Prototyping, Part 2 QuickView Test your polystyrene prototypes to measure and evaluate various aspects of the design and its performance. Then, write a brief essay about the results and whether you wish to make any changes to your design based on the tests.

Make any design changes.

Materials Go/No Go Gauge Prototype “Prototype Evaluation” worksheet

Engineering Design Process D – Prototype or model the solution.

E – Test and analyze the solution.

F – Redesign or improve the solution.

Procedure 1. Inspect your prototype. Compare it to your design. Is the shape of your prototype different from the shape of the car you envisioned? In what ways? Are there any features of your design that didn’t turn out right or that were more difficult to create than you expected? Write a paragraph that answers these questions on your “Prototype Evaluation” worksheet. You may also use a digital camera to take photographs that accompany your paragraph.

2. Use the Go/No Go Gauge to see how the measurements of your prototype compare to the final measurements you took of your design drawing. Write your results in the next available column on the “Design Specifications” data sheet. Label the column “Prototype.”

3. Were there any differences between the two sets of measurements? Were there any features that measured within the acceptable range in the drawing but not in the prototype? What are the reasons for these differences? Can you think of any tips for the construction phase to make sure the dragster you create is like your drawn design? Write a paragraph that answers these questions on your “Prototype Evaluation” worksheet.

4. If a wind tunnel is available in your class, use it to test how aerodynamic your design is. There are a couple different types of wind tunnel: • Does your wind tunnel use smoke or fog to visualize the way air flows around your car? When the smoke or fog goes around your car, you will be able to see if it moves smoothly over the surface or if there are eddies.

These eddies cause drag, which will slow your car down when it races.

• Does your wind tunnel not use smoke or fog but instead display a numeric value for the drag? The more drag measured, the less aerodynamic is your vehicle’s shape.

5. Write a paragraph on your “Prototype Evaluation” worksheet explaining how the car performed in the wind tunnel test. If you used smoke or fog, note any areas where it eddied. Also explain any ways you can see that your design needs to change to be more aerodynamic. Remember, speed is a big concern, but it is not the only one. The aesthetics of your car might also matter to you. If there is a conflict between the aerodynamics and 18

Student Instruction the look of the design, it is up to you to decide which is more important. You may include a photograph with your paragraph here as well.

6. It is time to make any desired changes to your design that you might have described in your essay. Instead of erasing and altering your original design, use a new “Multiview Design Sheet.� Mark it with the appropriate design number.

7. Save all your work in your portfolio.

19

Prototype Evaluation Worksheet

Student Designer/Engineer: _______________________________ Teacher: _______________________________________________ Date: ________________________ Car Name: _________________

Write your thoughts below. Consider the following questions: • Does the prototype you built differ from the way you envisioned it? How? • What aspects of your design were more difficult to create than you expected?

• Were there any differences between the measurements of your “Multiview Design Sheet” drawings and the measurements of your prototype? What caused these differences?

• What construction tips would you give to someone about how to cut out a prototype?

• If you conducted a wind tunnel test, how did your design perform? If you used smoke or fog, were there any eddies? Do the wind tunnel results cause you to reconsider any aspects of your design?

__________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________

21

Student Instruction Phase 5 Car Construction – From Prototype to Model QuickView Use tools to create a balsa wood or basswood car based on your prototype and design.

Materials Wooden blank Storage box Tools Copy of your current dragster design

Engineering Design Process D – Prototype or model the solution.

Procedure Transferring the design 1. Locate a printout or photocopy of your most up-to-date design. Do not destroy your original drawing. That must be kept for your portfolio.

2. Cut out the top and side views from your design.

3. Tape the side view to the wood blank.

4. Outline the side view onto the wood blank.

5. Push the pen or pencil through the side-view design at the two axle hole locations.

6. Remove the side view.

7. Tape the top view to the blank. Make sure the edges of the drawing are aligned with the side view.

8. Outline the top view onto the blank.

9. Remove the top view.

Shaping the car 10. Drill the axle holes.

11. You will now cut out the design from the blank. First, cut out along the side view. When you cut through the blank along the line, waste pieces will fall off. Keep these.

12. Gather the waste pieces and fit them back onto the working piece. Now, use enough bands of masking tape around the assembly to secure the pieces together.

13. Cut out the top view.

14. Now, you can throw away the waste pieces and masking tape.

15. Round the edges of your car. Do not sand aggressively.

23

Student Instruction Assembly 16. Gather a resealable bag, wheels, axles, straws, washers, and screw eyes.

17. Cut straws to fit the front and rear axle holes. The lengths should be the same as the body width at the front and rear axles.

18. Slide the straws, or axle bearings, into the axle holes.

19. Insert axles into the front and rear axle holes.

20. Insert one washer and wheel on each axle end.

21. Screw the screw eyes into your vehicle.

22. Write your name in pencil lightly on the bottom of your car.

24

Student Instruction Phase 6 Go/No Go: Collect Data – Meaningful Measurements QuickView Test several variables of your vehicle.

Materials “Car Specifications” data sheet “Meaningful Measurements” data sheet

Engineering Design Process E – Test and analyze the solution.

Procedure 1. Use the Go/No Go Gauge to check the measurements of your car. Are all its features within the allowed limits?

Write your results in the next available column on the “Car Specifications” data sheet. Label the column “Car 1.” Hopefully, your car meets all the specifications already. If not, there will be plenty of time later to make adjustments before the race.

2. Weigh your vehicle on the scale to ensure it is within specifications. In case changes were made, you will weigh in again before you test your car’s speed in the next activity, but this time it is for your personal information.

Record your information on the “Meaningful Measurements” data sheet.

3. Insert an empty CO2 cartridge into your car. Keep it in the car for each test you perform.

4. If a wind tunnel is available in your class, use it to test how aerodynamic your design is. There are a couple different types of wind tunnel: • Does your wind tunnel use smoke or fog to visualize the way air flows around your car? When the smoke or fog goes around your car, you will be able to see if it moves smoothly over the surface or if there are eddies.

These eddies cause drag, which will slow your car down when it races.

• Does your wind tunnel not use smoke or fog but instead display a numeric value for the drag? The more drag measured, the less aerodynamic your vehicle’s shape.

5. Note your observations on the “Meaningful Measurements” data sheet. Again, you may choose to supplement your notes with photographs.

6. Perform a ramp test of your vehicle. Place your car at the top of the ramp at the center and let it roll down.

Watch carefully as it rolls. Does the car look stable or does it wobble as it rolls? Problems with its roll can be caused by wheels that aren’t properly attached or by bad wheel alignment. Also note whether the car travels straight or goes off at an angle. A car that naturally travels straight will be a better performer. This is up to its wheel alignment. One thing this test does not tell you, however, is how fast your car will roll during the race.

7. You might have to perform multiple ramp tests to collect all the data. Note your observations on the “Meaningful Measurements” data sheet.

8. Save all your work in your portfolio.

9. This is a Go/No Go point. You may not advance until all students have completed their tests.

25

Car Specifications

Student Designer/Engineer: _______________________________ Teacher: _______________________________________________ Date: ________________________ Car Name: _________________

Acceptable Ranges

27

Car length

200 mm-305 mm

Wheelbase

105 mm-270 mm

Distance between screw eyes (proposed)

155 mm-270 mm

Body width – front axle

35 mm-42 mm

Body width – rear axle

35 mm-42 mm

Front axle length

42 mm-70 mm

Rear axle length

42 mm-70 mm

Rear axle hole from rear of wooden block

9 mm-100 mm

Bottom of front axle hole above bottom of wooden block

5 mm-10 mm

Bottom of rear axle hole above bottom of wooden block

5 mm-10 mm

Height of cartridge hole from bottom of wooden block to hole center

31 mm-35 mm

Clearance around cartridge hole

3 mm minimum

Teacher Signature: __________________________________________ Check one: ____ Go ____ No Go

Meaningful Measurements

Student Designer/Engineer: _______________________________ Teacher: _______________________________________________

Page 1 of 2

Date: ________________________ Car Name: _________________

Car weight: _________________

Observations from the wind tunnel test If your wind tunnel displays a numeric value for drag, what is your car’s value? __________________ If your wind tunnel uses smoke or fog, are there noticeable eddies? If so, where? __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ You may also draw a picture or include a photo to show where the eddies are located:

Observations from the ramp test Does your car look stable or does it wobble? If it wobbles, can you tell which wheel or wheels are making it wobble? __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ Does your car travel straight or go off at an angle? __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________

29

Meaningful Measurements

Page 2 of 2

Observations from the time trial How long did it take your car to travel down the track? __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ Do you have any other observations about its run? __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________

30

Design for Speed Part 2

Student Instruction Phase 8 Crunching the Numbers QuickView Evaluate the data from your time trial and calculate your car’s speed using the formula provided. Explore the meaning of this data in preparation for a redesign of your vehicle.

Materials “Need for Speed” data sheet Index card

Engineering Design Process E – Test and analyze the solution.

Procedure 1. You recorded your car’s time as it was launched down the track. Now, you will calculate its speed using the formula speed equals distance divided by time, or:

s= d t

After you know the distance and the time, you can calculate speed. Calculate this on your “Need for Speed” data sheet. Then, convert this number into kilometers per hour.

2. Reference your previous measurements of your car. On your index card, write the following pieces of information about your car: A. Finish time (in seconds) B. Speed (in kilometers per hour) C. Weight (in kilograms) D. Length (in millimeters) E. Wheelbase (in millimeters) F. Drag (only include if you measured your car with a wind tunnel that provided a numerical measurement) G. On the back of your index card, write your name and your car’s name.

3. How fast did your dragster go? The number doesn’t mean much unless you have something to compare it to.

On your “Need for Speed” data sheet, find the speed comparisons. The objects are arranged from slowest to fastest. Place an X where your dragster would go in this sequence.

4. Explore the difference between average velocity and instantaneous velocity.

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Need for Speed

Student Designer/Engineer: _______________________________ Teacher: _______________________________________________

Page 1 of 3

Date: ________________________ Car Name: _________________

Calculate your car’s speed using the formula speed equals distance divided by time, or:

s= d t

Show your work:

Convert this number to kilometers per hour. There are 100 centimeters in a meter and 1,000 meters in a kilometer.

Show your work:

Speed Comparisons The objects below are arranged from slowest to fastest. Place an X where your dragster would go in this sequence.

Snail – 0.048 kilometers per hour Person walking – 5 kilometers per hour Person on bike – 16 kilometers per hour Sprinting house cat – 48.3 kilometers per hour Car on highway – 96.5 kilometers per hour Top Fuel dragster – 531 kilometers per hour

33

Need for Speed

Page 2 of 3

Graphs

Speed

For each car, plot a single point on the graph that shows the speed of the car and the variable listed on the x-axis.

Speed

Weight

Length

34

Page 3 of 3

Speed

Need for Speed

Speed

Wheelbase

Drag

35

Student Instruction Phase 9 Analyze Data – Interpretation QuickView Look at data from all designs and determine the common characteristics of faster cars. Brainstorm in small groups to determine the common characteristics of faster cars. Create a graph that shows how various factors affect speed.

Materials “Need for Speed” data sheet

Engineering Design Process E – Test and analyze the solution.

Procedure 1. As a group, visually inspect the cars. They are arranged from slowest to fastest. Spend a few minutes looking at (but not touching) the cars. Also, look at the data written on the index cards. Try to identify features that are common among the faster cars and features that are common among the slower cars. Here are just a few questions you could consider while looking at the cars: • Do most of the fast cars share a similar shape?

• Can you see a relationship between how fast a car is and how much it weighs?

• Are there any features (such as fins or curves) that you see mostly on either the fast cars or the slow cars?

2. Discuss with your group what makes a car fast or slow. Discuss any patterns you notice. You might consult the Science of Speed glossary of terms to give your group ideas about what to discuss.

3. Each person in the group should plot the points on the Speed and Weight graph on their “Need for Speed” data sheet. You are creating a scatterplot.

4. Each person in the group should plot the points on the Speed and Length graph on their “Need for Speed” data sheet. You are creating a scatterplot.

5. Each person in the group should plot the points on the Speed and Wheelbase graph on their “Need for Speed” data sheet. (The wheelbase is the distance between the front and rear axles.) You are creating a scatterplot.

6. If you used a wind tunnel that displayed a numeric value for drag, each person in the group should plot the points on the Speed and Drag graph on their “Need for Speed” data sheet.

7. For each of the graphs drawn, estimate and draw a line of best fit or write, “No line of best fit.” The line of best fit will help you see any trends in your data. Though there are more precise ways to make a line of best fit, you will just try to see an imaginary line going right through the middle of the scattered data points. Here are a few examples of what this might look like:

No line of best fit

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Student Instruction Phase 10 Propose and Make Modifications QuickView Write a short essay explaining the changes you propose to make to your vehicle. You will then create new scale drawings of the top and side views. The drawings will be checked with the Go/No Go Gauge to ensure the new design is within specifications.

Materials “Proposed Changes” worksheet New “Multiview Design Sheet” Go/No Go Gauge

Engineering Design Process F – Redesign or improve the solution.

Procedure 1. You will now consider the changes to your vehicle design based on the data you learned from the launch tests.

On the “Proposed Changes” worksheet, answer the five questions. Write one paragraph for each question.

Paragraphs should be at least three sentences each. You don’t have to propose a change for every part of your car, but you must propose at least three changes that aim to improve either the speed or the aesthetics of your vehicle.

Note: Remember that speed isn’t necessarily everything. You have spent a lot of time studying speed, but the aesthetics of your car might be just as important to you. And that is perfectly OK! The world needs coollooking cars just as much as it needs fast ones. But if you make any design decisions that don’t maximize speed, just know that you might have to stick up for your ideas!

2. Create a new scale drawing of your vehicle. Create top and side views. You can use your most recent scale drawing as a reference, but you must draw your new design with the modifications you explained on the “Proposed Changes” worksheet. You will make your drawing on a new “Multiview Design Sheet.”

3. Measure your new design with the Go/No Go Gauge to ensure it is within specifications.

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Proposed Changes

Student Designer/Engineer: _______________________________ Teacher: _______________________________________________ Date: ________________________ Car Name: _________________

Write a paragraph of at least three sentences for each of the five questions below.

1. Explain what is more important to you, the speed or the look of your car. If they are equally important, you can say that as well. Explain whether you plan to emphasize the aesthetics or the speed in your redesign – or if you want to strike a balance between the two. ____________________________________________________________________________________________ ____________________________________________________________________________________________ ____________________________________________________________________________________________ ____________________________________________________________________________________________ 2. Consider what you discovered in the last activity about the way design affects speed. What design features make for a faster car? Why do you think these features make the cars faster? ____________________________________________________________________________________________ ____________________________________________________________________________________________ ____________________________________________________________________________________________ ____________________________________________________________________________________________ 3. Based on your observations, what changes do you propose to make to your car? Be specific. Explain what effect you think each of these changes will have on the performance of your car. ____________________________________________________________________________________________ ____________________________________________________________________________________________ ____________________________________________________________________________________________ ____________________________________________________________________________________________ 4. Based on your proposed changes, predict how well your car will perform. Be bold! Predict a performance time.

Give reasons you think your car will perform this way. ____________________________________________________________________________________________ ____________________________________________________________________________________________ ____________________________________________________________________________________________ ____________________________________________________________________________________________ 5. If you could make any changes you wished to your car, what changes would you make? Explain why you would make those changes. You are just imagining here, so you don’t have to stick to the specifications. You can let your imagination go wild. ____________________________________________________________________________________________ ____________________________________________________________________________________________ ____________________________________________________________________________________________ ____________________________________________________________________________________________

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Student Instruction Phase 11 Go/No Go: Design Modifications and Detail QuickView Make modifications to your car based on your new design. When the car is ready, conduct tests of your car and measure it to ensure it is within specifications.

Materials Car “Multiview Design Sheet” Woodworking tools Painting supplies Testing equipment

Engineering Design Process F – Redesign or improve the solution.

Procedure 1. Examine your car and your newly drawn scale images. Before you make any modifications, it is important that you think through the process of making them. If you don’t do a little bit of mental planning, you will be likely make a mistake that you will regret.

2. Make the proposed changes to your vehicle. Your teacher will indicate which tools and materials are available.

3. Sand your vehicle to remove the rough edges. Do any final detail work to the body – but do not paint the car yet and do not add the wheels.

4. Check your car with the Go/No Go Gauge to make sure it is within specifications. You know the drill by now!

5. Paint your car to make it look how you want it to look. If you have decals or other elements that need to be put on after the paint, wait until the paint has dried.

6. Conduct tests of your car. Use the same tests that you used for your prototype. Ramp tests, roll tests, wind tunnel tests, and weighing the car are all possibilities, depending on the equipment available in the class.

7. Are you happy with the way your car performed in the tests? Are you happy with the way it looks? Aesthetics judging and race day are coming up.

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Student Instruction Phase 14 Collect Data QuickView Complete your “Final Results” worksheet and discuss the results of the race. Assemble your portfolios and turn them in.

Materials “Final Results” worksheet All portfolio materials (all your data sheets, worksheets, drawings, and at least one photograph of your finished car)

Engineering Design Process E – Test and analyze the solution.

Procedure 1. Complete your “Final Results” worksheet.

2. Do any remaining work in your portfolio.

3. Assemble your portfolio. Make sure you have all your data sheets, worksheets, drawings, and at least one photograph of your finished car.

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Final Results

Student Designer/Engineer: _______________________________ Teacher: _______________________________________________

Page 1 of 2

Date: ________________________ Car Name: _________________

What was your vehicle’s time in the Day at the Races event? (If you raced multiple times, use your best time.)

Calculate your speed from this time.

What was your speed during the trial race?

Did your speed increase or decrease?

What was the percentage of increase or decrease?

What was the time prediction you made on the “Proposed Changes” worksheet?

How close were you (in seconds)?

If you could make additional changes to your car, what changes would you make? Why?

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Final Results

Page 2 of 2

What was the most surprising thing you learned while creating your CO2 car?

What advice do you have for the next designer?

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Glossary Note: This glossary contains terms from both Let’s Get Moving and Design for Speed.

aerodynamics – the study of the movement of objects through air and other gases aesthetic – the consideration of outward appearance or beauty alignment – being situated in a straight line average velocity – the overall speed of an object over an elapsed time axis – a line around which an object rotates brainstorming – generating several ideas quickly before selecting the best one circumference – the length around the outside edge of a circle double elimination – a type of tournament in which competitors are ruled out after losing two rounds drag – a force that resists the motion of an object moving through air or another fluid dry friction – friction between two solid, non-lubricated surfaces eddy – a small current (such as in air) that moves in an opposing direction from the main current, causing drag experiment – a scientific method to make a discovery or test a hypothesis fluid friction – friction between an object and a fluid such as air or liquid force – power exerted on an object friction – the resisting force that occurs when two objects moving at different speeds rub together gauge – a tool for quickly measuring hypothesis – a proposed explanation that can be tested with an experiment instantaneous velocity – the precise speed that an object is moving at a given instant lubricant – a substance that is designed to reduce friction on the object it is placed on mass – the amount of matter in an object (similar to weight but not exactly the same) momentum – the force with which something moves pascals – the standard unit for pressure; one newton per square meter 45

Glossary pit stop – a brief rest during a race for refueling and minor repairs polystyrene – a type of stiff foam portfolio – a place for storing completed work pressure – a continuous force on an object from another object in contact with it prototype – a test model that is made before creating the final product PSI – a unit for measuring pressure; pounds per square inch radius – the distance from the center of a circle to its outside edge range – a set of numbers that a value must fall between scale – the ratio of the size of a drawing compared to the actual size of the object scatterplot – a data table that uses individual points of data to show a relationship between the values on the x-axis and the values on the y-axis

single elimination – a type of tournament in which competitors are ruled out if they lose one round specification – a requirement that a design must meet thumbnail – a small, quick drawing made to illustrate a rough idea trial – an attempt at doing something variable – something that can be changed in an experiment viscosity – the thickness of a fluid; its resistance to flowing volume – the amount of space an object takes up wheelbase – the distance from the center of the front wheel to the center of the back wheel

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Parts, helpful hints, videos – you’ve got the green light.

Visit www.science-of-speed.com.