Electric Drag Race

The information on this event is up to date.

Faculty coordinators: Professor Roy Clarke [royc@umich.edu].
Preparation Team and Judges: Lynn Endicott, Abe Oraiqat, Daniel Wilcox

Event Description:

Teams of two students will design, construct and race a model car powered by electricity from an ultracapacitor. This is a device for storing charge, with a surprisingly large energy density. 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 three times for each team will be used to determine the winning time. Each team’s score on a quiz, designed to test basic physics concepts related to solar energy, electric energy storage and motion, will be used in the event of a tie.

Event Location and Time:

Sidewalk outside the Dennison Building.
In the case of bad weather: Randall 2^nd-floor Hallway.
10:30AM - 11:50AM and 1:00PM - 2:50PM

Apparatus and Materials:

Prior to the competition:

Each team will design and construct a model car driven by an electric motor. The motor will be powered by an ultracapacitor which will be pre-charged by a solar panel (or in the event of cloudy weather, a constant voltage power supply). The ultracapacitor, the motor and a switch will be supplied by the event organizers in advance. A solar panel, or other power supply, will be available to each team at the time of the race. This will be used to charge the ultracapacitor to a maximum of 2 volts. The solar cell will then be disconnected from the ultracapacitor and the stored charge will then be used to power the electric motor. A switch will be supplied to release the stored charge to the motor at the beginning of the race. Note that the solar panel itself will not be included in the design of the car, its only purpose is to provide the initial charge for the ultracapacitor. 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 ultracapacitor provided. No substitutes are permitted. A AA battery (1.5 volts) 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 to charge the ultracapacitor, or connected directly to the motor, but no batteries will be permitted during the race. Do not exceed 2 volts when charging the ultracapacitor.

Support equipment during the competition:

Contestants may bring any tools, equipment and supplies they wish to support their model car. 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 of bad weather on the day of the event (as sometimes is the case in early May) the race will be held indoors (in a hallway of the Randall Building) using a fixed voltage power supply (2 volts) to charge the supercapacitor. The power supply will be provided by the event organizers.

Event Rules:

Teams: Each team shall have two members.
Quiz: Prior to the start of the competition each team will take a written quiz. The questions will be based on the following topics: energy, power, sunlight, solar energy conversion from light to electricity, and motion (including speed and acceleration). The time allotted for the quiz is 15 minutes.
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 three goes and the fastest time of the three 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:

Each team will run their car over the prescribed track three times. The fastest of these three times is used to determine the winning time.
Ties: In the event of a tie, team’s score on the quiz will be used to break the tie.
Awards: Gold, Silver, and Bronze medals will be awarded to the teams with the best times.

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.
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.
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.
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.
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.
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 parts kit containing useful items for building your model car. Two of these items, the ultracapacitor 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. A switch will be provided to release current from the ultracapacitor at the beginning of the race, to power the motor. Additional sources for supplies and materials may be useful:

Most of what you need for a successful design can be found in the parts kit provided. Additional items that might be useful for this project may be found around your home or at hardware stores: Good hardware stores (like Stadium Hardware in Ann Arbor) carry a wide range of small plastic parts suitable for constructing a light wheels platform.
Ryder's Hobby Shops: The Ryder's Hobby chain of stores stocks a good selection of materials and supplies including small gears and sprockets.
The Internet is a good source of information and online supplies for constructing your model car.

Finally: TEST EARLY and TEST OFTEN !!

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Electric Drag Race