Solar Wheels
The information below is subject to change as
more event tips and details are included. Please monitor this page
regularly.
Faculty coordinator: Professor Roy Clarke [royc@umich.edu].
Event Description:
Teams of two students will design, construct and race a model car powered by solar energy. Points toward the team's final score are awarded for the car's performance in a timed
race as well as the team's score on a quiz. Cars will be timed over a prescribed distance. Cars will travel in a
nominally straight line and will be timed over the length of the track. The race track will be
approximately 30 feet long and 15 feet wide. The shortest of two times (in seconds,
rounded to the nearest second) for each team will be subtracted from 50. The resulting number, multiplied by 2, comprises the race
score for the event. The fifty-point quiz is designed to test basic physics concepts related to solar energy and motion. The event
score for a team is the sum of the race score and the quiz score. In the event of a tie, the fastest race time wins.
Event Location and Time:
Sidewalk outside the Dennison Building.
In the case of bad weather, the event will take place at an inside location (TBA).
10:30AM - 11:50AM and 1:00PM - 2:50PM
Apparatus and Materials:
Prior to the competition:
Each team will design and construct a model "solar car"
powered by the solar panel and electric motor supplied by the event organizers in advance. The solar panel dimensions are
approximately 4" x 2 1/2" x 1/4". The motor is approximately 3/4" diameter x 1" long.
Contestants are free to choose any design they wish (and it need not conform to that of a car, as such),
but they must use the motor and solar panel provided. No substitutes are permitted.
Batteries may be used to test the car, but no batteries of any kind will be permitted during the race.
Car Testing: It is recommended that cars be tested thoroughly before the day of the event to
ensure straight running and to optimize performance. The mechanics can be tested with a AA battery connected
to the motor instead of the solar panel, but no batteries will be permitted during the race.
Support Equipment during the competition:
Contestants may bring any tools, equipment and supplies they wish to support their solar wheels.
No support equipment or materials will be provided. Tools, equipment and supplies may be brought to the
race area and staged before the official race window begins.
No additional tools or materials may be brought
to the race area once the race window has begun. Last minute
adjustments to the cars will be permitted at the discretion of the Race Director.
Bad weather option:
In case the sky is not cloud-free on the day of the event (as is often the case in early May)
the race will be held indoors (in a hallway of the Randall Building) using high intensity lamps as a substitute for the sun.
These lamps (Task Force Model 227293 from Lowe's) will be provided by the event organizers.
Event Rules:
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Teams: Each team shall have two members.
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Quiz: Prior to the start of the competition each team will take a written quiz worth 50 points.
The questions will be based on the following topics: energy, power, sunlight, solar energy
conversion from light to electricity, and motion (including speed).
The time allotted for the quiz is 15 minutes.
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Starting Time: Each team shall be assigned a starting time, at random, prior to the start of the race competition.
- Ready Area: The team next in line to race
will stage their models and equipment in the designated ready area.
- Race Area: Only team members and officials are allowed in the race area during the competition,
and no outside assistance or advice may be given to a team during the race. Any team receiving outside assistance will be disqualified.
Contestants are not allowed to have physical contact (other than light) with their car during the race,
including externally disturbing the air around the car to make it go faster.
If a car stops during a race, contestants are allowed to restart it, but only with a
small push, enough to get over the obstacle. Teams whose car drives outside of the
designated race area before crossing the finish line will not receive a time for that heat.
- Timing: The official time for each race is defined as the interval from when the front wheels
of the model cross the start line to when the front wheels cross the finish line. Each car will
have two goes and the fastest time of the two will be used as the team's race time.
- Repairs: Models may be repaired as required during the race window, but no
additional time will be allotted for repairs. No repairs may be made during the race itself.
Judging Criteria:
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Total Score: Each team will run their car over the prescribed track twice.
The times for each race will be recorded and rounded to the nearest second.
The shortest of the two times (in seconds, rounded to the nearest second) for each team will
be subtracted from 50. The resulting number, multiplied by 2, comprises the race score for
the event. The total event score for a team is the sum of the race score and the quiz score.
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Ties: In the event of a tie, the team with the fastest race time shall be declared the winner.
- Awards: Gold, Silver, and Bronze medals will be awarded to the teams with the highest three total scores, respectively.
Hints and Tips for Competitors:
Improving Performance: There are many technical aspects that go into a well designed solar wheels platform. These include:
- Straight running: if your car does not maintain a reasonably straight course it will run out
of bounds and be disqualified. It is very important to make sure the car can run over 30 feet without
veering off significantly to the left or the right. Getting this right is one of the most important
design requirements for this event. Test your design thoroughly before the event to make sure it runs true.
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Light Weight: Lighter models will accelerate faster, but are more easily damaged
and may be less stable. Experiment to find the best compromise between light weight,
stability and robustness. Choose your construction materials with these aspects in mind.
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Wheel size: larger wheel diameter helps with overcoming obstacles on rougher surfaces (like brushed concrete),
but requires some thought how to couple efficiently to the motor.
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Drive coupling:
coupling the motor to the drive wheels is a key part of the design. There are many ways to do this, from rubber bands to gear
sprockets. Experiment with various designs to get the most efficient transfer of power from the motor to the wheels.
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Friction: Friction between the road and the wheels is necessary for traction, but in some other components
friction needs to be minimized. Lubricating the axel supports / bearings with light oil improves performance.
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Safe Storage: Preserve your models in good racing condition by storing and transporting them in a box,
such as a cardboard or plastic household storage container.
Sources for Supplies and Materials:
The event organizers will provide, in advance, a kit containing several items for
building the solar car. Two of these items, the solar panel and the electric motor, must be used.
No substitutes are allowed for these two items. In addition, some other items provided, like gears and sprockets,
pulleys, wheels, etc., may be used at the team's discretion. Other sources for supplies and materials may be found:
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Some of the items you will need for this project may be found around your home.
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Hardware stores: Good hardware stores (like Stadium Hardware in Ann Arbor) carry a wide range of
small plastic parts suitable for constructing a solar wheels platform.
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Ryder's Hobby Shops: The Ryder's Hobby chain of stores stocks a good selection of materials and supplies including
small gears and sprockets.
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The Internet is a good source of information and online supplies for constructing your model solar wheels.
