Step 1: Short Intro Lecture
Project overview, goals, rules-requirements-constraints, design process, the systems of the car. Please note these are generally the steps LBMS takes to design, test, and race the cars in a 2 to 3 week period.
Step 2: Understanding the problem and the constraints
- Look at the example car from past students that was given to
your group to study. Please be very gentle and careful. Each person, sketch THIS car into your own composition book first as an orthographic sketch (top, front, right side), then as an isometric sketch
- the driven axle and the non-driven axle,
- the chassis and what material it was made out of.
- the solar panel structure and if it has a flat, fixed or has an adjustable angle.
- Now answer the following questions on the same page as your sketch:
- How the individual ‘systems’ of the car get assembled?
- What material was used as the axle bearing?
- How much does the car weigh in grams?
- The solar panel holder system holds the panel how high in millimeters above the chassis?
- Think you’re done? Look at these past student examples. Do NOT go on until you show the teacher your sketches – it’s a grade!
Step 3: Analyzing Data from Past Cars
- Now, in each of your composition books, make a table with the following ‘columns’: Name of car, race time in second, weight of car, number of teeth of the gear on the axle (driven gear), number of teeth of the gear that’s on the motor (drive gear), and the gear ratio.
- Now…each person login to Chrome and your Google Classroom. Click here for a list of race results from LBMS. Know how to scroll to the right?
- Fastest times: In each of your composition books, fill in the information you just made in the table above for the fastest 3 cars
- Now, gather the same data for random 3 cars that have times between 20 and 60 seconds. (Thanks Aya for the suggestion)
- Look at your data and compare the fast cars to the slow cars. With the members of your team, see if there are any patterns and if you can possibly draw conclusions on ‘why’ the fast cars went fast and the slow cars went slow and write this down into your composition book.
- Together, watch the following movies – #1 and #2 and #3. Now…make a list in your composition book of ‘other things’ that could affect the performance of a car that you couldn’t deduce from the data.
Step 4: Research
Look at the example cars from past students. Note where the motor has been positioned, what types of gears are on the axle and the motor,
Now, do some searches online, looking for pictures of JSS cars from other students around the country.
- NOTE: How can you ‘take’ ideas from other cars and alter them, evolving that idea to make a better design? Also remember – don’t STEAL.
- REMEMBER…you must design your vehicle so that all parts can either be recycled or reused
Step 5: Brainstorm ideas / Sketch
Step 5A: Start first with ‘thumbnail’ sketches – focusing on a ‘TOP VIEW’ of the chassis’ shape as well as where axles/wheel will be placed. Be creative! Think inside and outside of the box. In fact – don’t draw ANY ‘boxes.’ Try to make lines smooth and aerodynamic, like a bird or airplane. Click here for some examples. Quickly sketch 9 different ‘chassis’ configurations in each of your composition books like the example above. Each of the team members should have DIFFERENT ideas/sketches – meaning, don’t copy off each other. You don’t have to label anything, but you certainly can, if you wish.
Step 5B: Each person pick which thumbnail would be their best design (from their OWN 9 thumbnail sketches) and sketch a larger, more detailed sketch of JUST THAT ONE.
This should be a pretty good sketch. If you can, do an orthographic and/or isometric, but you don’t have to.
Step 5C First – look at each other’s best design. Discuss and pick which plan which one you will start building as your first prototype.
- Where will you get materials? What team members will bring what?
- Both team members -together take your sketches up to the teacher. Show the teacher your thumbnails and the larger sketch. Tell him which design you’ll be making.
- If given the ‘okay’ you’ll get some materials from the teacher – if you wish to use them.
- As a group, watch the movie on utility knife safety (click on picture). When you’re done, take the quiz
- Tell the teacher when you’re done
- When the first group is done, the class will be stopped and a ‘demo’ will be given on use of the available tools, how to use them, safety procedures, cleanup procedures, and strategies on teamwork and how to best use available time
- Utility knives: Path of blade, what other tools to use them with, retraction of blade, how to get blade replaced if dull
- Cutting board, safe-t-bar
Step 7: Grading and goals
In the next steps, you’ll be using measuring and cutting tools to make your chassis according to your plan. Be as precise as you can using these tools. Remember that the instructional movies and the live demonstrations are there to help you do your best. Rewind movies to see over again if you don’t understand. Ask the teacher questions. Don’t be afraid to start over again. Learn from your mistakes. Once you learn the basics, doing something over again takes less time.
The goal at this point: make a working prototype (car goes at least 3 meters) with a high degree of precision. Click on the picture to ‘preview’ how you’ll be graded.
Step 8: Measure, mark, cut the chassis.
Before starting this step, watch the movie to the right
- First cut a small bit off of one edge for your ‘reference’ side. Mark that edge with an ‘x’
- Layout/cut the the width and then the length of chassis with rulers and T-squares.
- Super important: Mark where axles are to be placed with T-square to ensure parallel axles
- Cut the ‘slot’ where driven axle gear will be
- If your chassis has a ‘shape’ other than a rectangle, cut that out now.
- Show the teacher your finished chassis
Interjection: Gears What gears will you be using and why? What’s the math behind it? Can you try different gear combinations (resulting in different gear ratios). How do the size of wheels relate to the gear ratio?
Step 8: Axles
- NOTE: Before gluing, you MUST have the teacher check your work.
- Driven axle
- Put the gear on the driven axle and locate it to fit in the slot
- Glue your axles to your chassis as accurately as possible
- Test your car (still without the motor) on the test ramp. Check for turning. If your car turns, tear off and re-glue the non-driven axle (the axle without the gear)
- Driven axle
Step 9: Attach Motor and Test
- Attach the motor to your chassis. Be sure to glue with the cooling ducts facing upward
- You can use a motor mount, but consider the pros and cons, especially how it affects testing
- Let the glue dry and with a battery pack test your car. Observe any turning, how fast the car goes, how quickly it accelerates, and any possible friction issues.
Step 10: Solar Panel Structure
- Look at past cars and their solar panel structure. Remember – WEIGHT – one of the biggest factors. Design with simplicity in mind.
- Solar panel structure must: hold the panel so that the panel can’t fall off during race; allow the leads of the motor to attach to the leads of the panel; must be able to switch out panels quickly if needed
- Trade offs: will your car go faster if you make the panel holding structure horizontal (least weight) or at an angle (what angle?) or adjustable?
- Build and glue your solar panel structure and attach it to your chassis – then test your car with the battery pack panel. Adjust if needed
- LBMS Weight and Balance Test: You must show that your car can balance with a solar panel attached
Interjection: Aerodynamics. What if the race is on a windy day? Will your car flip over if the wind grabs a hold of it? What design ideas can you implement to reduce any ‘drag’ caused by wind.
Step 11: Guidance System
- Look at past cars and how they attempted to design and build their guidance systems
- Trade-off: One contact point system or two? If only one, which end of the car should it be on?
- Note: The guidance system is critical. Some cars that run incredibly on their own, won’t run at all when on the race wire. Point? Spend time designing and testing your guidance system.
- LBMS Line Test: You team must prove that you can attach your car to the race wire (test race track) in under 30 seconds and that the car runs the entire 10 meters of the test track.
Step 12: Optimization
- Observe the running of your car. Brainstorm how you can do any of the following:
- Make it weigh less
- Make the moving parts produce less friction
Step 13: Data input
- Using the online data input form, submit your car’s data. Note: This MUST be done BEFORE the race, or your car is automatically disqualified.
- Click here to submit your data