The 20th annual Solar Car Challenge is happening at Cal Young Middle School on June 10th from 9:30-1:30 ish. Our science classes will be sending one or two of the fastest cars from each class to compete in this annual race.
Monday, May 22-Friday May 26
- Finish the actual size drawings showing 3 views of your car design, top, bottom and side view. Each person in the group must complete a drawing.
- Get the drawing approved and initialed by Ms Hohenemser. Staple your pink planning sheet and your green scoring rubric and turn in to the basket at the end of the period. It will be returned to you the next day
- Fill out your Materials Request Form (green) with our names and the parts you need to make a rolling chassis and to prepare for the roll down test (up to gears). You will need the wood or foam core for the chassis, axels, wheels and gears.
- Bring the filled our Materials Request form to Ms. Hohenemser and receive your parts. You will need to bring this form any time you want to trade out parts or get new ones
- Trace the outline of your chassis (body shape) using the overhead projectors onto a blank piece of white paper. Cut out the shape with scissors and put all scraps in the recycling
- Attach the traced drawing to the wood/foam with tape and trace around it onto the wood/foam core
BEFORE you CUT….Use the triangle to make parallel lines on your wood to show EXACTLY where the axels will be attached. Make some extra parallel lines so that you can line other items up. - Check out a knife and get a cutting board from Ms Hohenemser’s computer cart at the front counter and cut out your balsa wood/foam core. (she will do a demonstration in class)
- While one student is cutting the chassis out, the other partners will take photos of the progress for the keynote journal and get the bushings axels and gears ready. In some cases you may want to mount your bushing before you start cutting at all.
- Cut your axels to the right length and file the sharp ends by following the directions in this video
- Use hot glue to attach your bushings to the chassis (Check out this video at 2:48 to see how to attach the bushings and axels.) Place the gears and attach the wheels.
- You are ready for the Roll Down test. Get the Yellow Roll Down sheet from the front counter file folder and make your measurements. Record your Roll Down score on the bulletin board data table as well as the class spreadsheet on your teachers computer. A score of 20 or higher is generally good.
Friday June 2-Tuesday June 6th
12: After you have completed your roll down test to your satisfaction, filled out the sheet and turned it into the turn in basket and record your scores on the spreadsheet on your teacher’s computer, it is time to get your motor, wiring, mount and battery pack signed out and attached.
13. Bring your Green materials sheet to the front counter with the items listed above filled out. You can choose from a prewired motor or do your own wiring. You will attach your motor with hot glue and your battery pack with velcro (please do not glue it). If you plan to use a motor mount you can also ask for some tiny screws to attach the motor to the mount. Be careful not to get glue in the teeth of your gears.
14. The important thing about mounting your motor is to get the gear spacing perfect. Gears that are too tight will reduce the rotational force that comes from your motor and slow down your car, but gears that barely touch each other will also not move your car very fast. You have to find that perfect sweet spot where they make good contact but don’t exert too great a force on each other.
15. Once you have mounted your motor with a pinion gear, attached your battery pack with velcro and inserted your used batteries, it is time to take your car “out for a spin”, Get a green speed sheet for your group from the file folder on the table under the whiteboard. Your initial speed test will be completed on the track in the back off the classroom. This track is marked at 8 meters in length. In order to calculate your speed you will divide 8m by your car’s time in seconds. There are some timers on the counter near the track. You may also use your iPad or phone for timing. For example 8 meters in 4 seconds would be 8/4= 2 m/s. A fast speed on this track is about 3 m/s. Record your speed on the bulletin board chart as well as on the computer spreadsheet.
16. Once you are happy with your time trials on the 8 meter track, you are ready to set up the hallway track and get a 20 meter speed that should be faster than your 8 meter speed. You may need to add some traction to your drive wheels (the ones that are connected to the motor) You can use rubber bands or part of an inner tube from a bike tire. You may also decide that you want to make some kind of bumper for your car if it always pulls to one side. Possible materials are aluminum axel material or zip ties or anything else you can think of.
17. Once you are happy with your hallway speed without a solar panel, record your top speed on the bulletin board data table and the computer spread sheet as well as on your green speed sheet. It is now time to attach your solar panel. A good time for the 20 meter track without a solar panel is 5- 6 seconds. So the speed would be 20 m/ 6 sec = 3.3 m/s 20m/5 seconds= 4 m/s.
18. Now it is time to attach your solar panel mounts. Use the scraps that you made cutting out your chassis or any of the balsa scraps from the scrap box near the table by the whiteboard. The solar panel mounts should be glued down, but your solar panel MUST BE ATTACHED WITH VELCRO. You teacher will probably give you a broken solar panel to test with unless there is an outdoor track set up.
19. For you last require speed test you must run your car in the hall with batteries and the the solar panel. Record your speed in m/s on the bulletin board data table and computer spreadsheet. This speed will be slower than without the panel. Finish your green speed sheet and turn it into the turn in basket. If we have time, we will set up an outdoor track.