Solar Car

Introduction: (Initial Observation)

Solar Racer activity introduces students to alternative energy concepts while incorporating problem solving, design and modeling. In addition, students will experience using hand tools as they construct their solar vehicle.

The solar car activity may be tried as a science project or as a technology/ engineering project. In either case design and construction of the solar car is the first part of the activity.

As a technology/ engineering project your model car will be evaluated based on design features and performance.

Teachers may arrange a car race as one step in evaluating the performance of solar cars made by different students.

As a science project, you must use your solar car to study one factor such as the angle of solar panel or the angle of sunlight to see how do they affect the performance (speed) of the car. More advanced students may make larger solar car models with 2 or more solar panels.

In this project guide we will provide you with steps of trying solar car project as a Science Project.

Information Gathering:

Find out about solar energy and how it can be used. Read books, magazines or ask professionals who might know in order to learn about the ways you can maximize the use of energy from the sun. Keep track of where you got your information from.

Following are samples of information you may find:

Background

The federal government has encouraged alternative forms of transportation due to a limited supply of oil and increasing environmental pollution. Solar cars are just one of many transportation concepts emerging. Solar cars use solar cell panels instead of gasoline as the fuel. As a result, exhaust fumes and oil consumption are eliminated.

The solar cell panel generates an electrical charge that is stored in a battery and used to provide energy as the vehicle is driven. The lighter the vehicle, the less energy used and the farther the vehicle will travel. In cloudy days, or at night, energy can be drawn from reserve batteries. In the future, charge stations will be located on the road sides for quick battery charging.

Gear Propulsion Solar Car

Introduction:
MiniScience’s Solar Racer activity introduces students to alternative energy concepts while incorporating problem solving, design and modeling. In addition, students will experience using hand tools as they construct their solar vehicle.

Teacher Preparation:
During construction of the solar racer vehicle, students can experiment and comprehend methods of power transfer, soldering (optional), gear alignment and calculating gear ratios. It is up to the teacher to make sure this background information is provided to students in some manner.

Propulsion Systems:

Propulsion systems include using a solar cell and toy motor with a:

• gear drive
• Pulley and Rubber band drive

Advanced students are encouraged to experiment with different size pulleys, and gears if available.

Basic Tools Required

These items may be required to build the solar vehicle: (You can make your solar car model without them as well)

• craft knife, used to cut or trim soft wood.
• White glue, wood glue or glue gun
• Soldering Iron, needed if you need to solder wires.
• Pliers, used to connect and twist wires together if needed
• rulers, used for measurements
• Pencil, used for marking

Safety Recommendations

During the construction of the solar vehicle, the following safety precautions should be observed.

• Wear safety glasses
• Use care with sharp cutting blades
• Avoid touching the tip of the glue gun or soldering gun
• Put safety first

Competition Categories

Competition between students can be based on design, drawings, final appearance, distance-traveled, speed, etc.

Races can be held between cars that have similar or different types of propulsion Systems.

In addition, teachers could implement a problem-solving category for advanced or older students. Teachers would provide students with the solar racer kit then instruct students to make use of additional materials in the classroom to construct a customized solar vehicle. additional items could include wood scraps, stickers, paint, CD, colored wheels and more. How elaborate or complex the solar cars are depends on imagination and resources.

Question/ Purpose:

What do you want to find out? Write a statement that describes what you want to do. Use your observations and questions to write the statement.

The purpose of this project is to design and construct a solar car model, powered by a solar panel and a small DC motor.

As a technology project, your car may be evaluated based on design, drawings, final appearance, distance-traveled, speed, etc

As a Science Project, you must study one specific factor or question. This is a sample:

How does the angle of sun rays affect the speed of a solar car?

Identify Variables:

When you think you know what variables may be involved, think about ways to change one at a time. If you change more than one at a time, you will not know what variable is causing your observation. Sometimes variables are linked and work together to cause something. At first, try to choose variables that you think act independently of each other.

This is a sample of how you may define variables:

• The independent variable is the angle of the sun rays.
• Dependent variable is the speed of the car
• Control variables are test ground and the condition of the sky. Perform all experiments in clear sky.
• Constants are the direction of the car and the test ground.

Hypothesis:

Based on your gathered information, make an educated guess about what types of things affect the system you are working with. Identifying variables is necessary before you can make a hypothesis.

This is a sample of how you may propose a hypothesis:

I hypothesize that the model solar car will drive faster when the angle of the sunlight is is the most (mid day). (This is the angle of sunlight with the ground)

Experiment Design:

Design an experiment to test each hypothesis. Make a step-by-step list of what you will do to answer each question. This list is called an experimental procedure. For an experiment to give answers you can trust, it must have a “control.” A control is an additional experimental trial or run. It is a separate experiment, done exactly like the others. The only difference is that no experimental variables are changed. A control is a neutral “reference point” for comparison that allows you to see what changing a variable does by comparing it to not changing anything. Dependable controls are sometimes very hard to develop. They can be the hardest part of a project. Without a control you cannot be sure that changing the variable causes your observations. A series of experiments that includes a control is called a “controlled experiment.”

Make the Solar Car

Introduction:

You must make a solar car that is well designed, strong and has low friction between the moving components.

Materials Checklist:

Following is a list of materials used in a solar car. (These materials are also available as a kit at MiniScience.com). Solar cars may be propelled using a pulley/ rubber band method or some types of interlocking gears. In this project we will use gears.

1. Solar Cell
2. DC motor
3. Rear Slicks 1 9/16″ diameter x 5/8″ wide (1/2″ wide for geared slicks)
4. Front Wheels 1 3/8″ diameter
5. 1/8″ dowel for axles
6. Traction Bands (for non-geared slicks)
7. Eyelets or washers
8. Straw
9. Wood Sheet 5″ x 2″ x 3/32″ (or larger, so you can cut to any size)
10. Basswood 5mm x 5mm x 20cm stick
11. Motor Mount (With straps if needed)
12. Gears or pulleys
13. Procedure Sheet or Grid Planning Sheet

Standard Assembly Steps

Before starting to assemble (put together) your solar car, prepare your design with exact location of the axles, wheels, gears and motors. Note that if you mount the motor in a wrong place, either the gears do not engage or they will create too much friction bringing your car to a halt.

1. Locate the grid planning sheet in the kit.
2. Using a pencil and ruler, design the body of the vehicle and propulsion system.
   Remember, the lighter the vehicle’s body, the further it will travel.
3. Show the drawing to the teacher when ready.

After your drawings are approved, Make your solar car model in 3 simple steps. The details of these steps may be different depending on your design.

Construct the basic car chassis with 4 wheels

Step 1:

Mount the axles:
Cut a strip of wood that is 2″ (5cm) wide.

Mark the location of axles by drawing two lines, one on each end of the car, parallel to the front or back side.

On the axle lines, mark two points that are 1/4″ (6mm) away from each side. Insert one eye screw in each of the points.

In the model shown here, the gears are built in the rear slicks (rear wheels). With plain wheels, you had to insert a pulley or gear in the same axle with one wheel.

If you don’t need to install pulleys or gears, continue with step 2.

Also read the second method of mounting the axle.

To mount a pulley or gear next to one wheel, it is a good idea to cut some space for that on your chassis; otherwise, one wheel will stand out and your model will not have a symmetrical shape. The size of this space may vary depending on the size of your pulley or gear.

(3/8″ x 1 1/2″ cut is shown in this example)

This is how a pulley or gear may be mounted beside one of the wheels. The pulley or gear must have a hole matching the axle diameter and must feet snugly. Some pulleys and gears require a plastic insert and some drilling in order to adapt the diameter of the axle you are using.

After mounting, make sure that the wheels can spin freely. If necessary, mount a metal washer between the spacer and eye screws.

You may not have eye screws for mounting the axles. This is an alternate method for mounting wheels and axle.

Insert the axle in one wheel, slide a washer onto it. Insert a 5 1/2″ straw over it and finally insert another washer and another wheel.

Your final wheels and axle will look like this. Hold the straw and spin the wheels. Make sure the wheels can spin freely. If necessary, make some adjustments.

Cut 4 pieces of 2″ (5cm) long wood strips and glue them about 1/5″ (5mm) apart where you want to mount the axles.

Insert the axle in the space between the strips and secure them in place using some glue. Cover it with a strip of cardboard or heavy construction paper.

Note that the glue will touch the straw, not the axle. This is how the bottom of your car will look like after covering the axle holder with a strip of paper.

Step 2: Mount the motor

Insert the small gear or pulley onto the motor’s shaft. Place the motor on the self adhesive motor mount and strap it securely and snugly.

Place the motor on the car while the car is on a flat surface. Move it towards the gears until the gears engage. Mark the location of the motor. Avoid too much pressure on the gears because it will increase the friction and make it difficult for the car to move.

If you use pulleys to transmit force, motor must be mounted away from the pulley so that the rubber belt is slightly stretched.

Carefully peal off the protective cover of the adhesive pad. Make sure you will not remove the adhesive pad itself. Place the motor where you already marked. Push it down firmly to stick in place.

Step 3: Mount the solar panel

Place the solar panel on the car. Connect the solar panel to the motor (if they are not already connected).

The solar panel may be mounted horizontally or slanted. It may be secured in place using a few pieces of clear tape.

Take the car outside in a sunny location and test it. Does the motor run while you have the car in your hand? Do the wheels spin? Now place the car on a smooth flat surface so that the solar panel is faced to the sun. Does it run on the ground?

The final solar car you make may be different based on the materials you use, the design implementation and additional decorations you may add.

Decoration may include wooden or cardboard pieces you can add or paints you may use.

Experiment the angle of the sun: How does the angle of sun rays affect the speed of a solar car?

1. Mount the solar panel horizontal. You may use cardboard or Styrofoam and some tape to support it.
2. Find a flat and smooth surface for your test. If the ground is not smooth, tape sheets of construction paper on the ground to make a smooth runway.
3. Bring you car to the beginning of the runway while the solar panel is covered by a black paper or black cloth.
4. Set the timer or stopwatch and immediately remove the black paper or cloth. Also make sure that nothing else is blocking the sunlight.
5. Stop timing immediately at the end of the runway. Record the travel time. Divide the travel distance to travel time to calculate the speed. Repeat this 3 times.
6. Repeat the steps 3 to 5 at least 5 times during a sunny day with clear sky. Each time also measure and record the angle of the sun.
7. Record you findings in a table like this:

How to measure the angle of the sunlight?

Hold a meter stick vertically on the ground. Measure the length of the shadow. Now that you know the length of the meter stick’s shadow, plug your measurement into the calculator below to determine the angle of the sun above the horizon.

Materials and Equipment:

This is a sample list of materials.

1. Solar Cell (MiniScience product code SOLARP.6W)
2. DC motor (MiniScience product code RE140RA)
3. Rear Slicks 1 9/16″ diameter x 5/8″ wide (1/2″ wide for geared slicks)
4. Front Wheels 1 3/8″ diameter
5. 1/8″ dowel for axles
6. Traction Bands (for non-geared slicks)
7. Eyelets or washers
8. Straw
9. Wood Sheet 5″ x 2″ x 3/32″ (or larger, so you can cut to any size)
10. Basswood 5mm x 5mm x 20cm stick
11. Motor Mount (With straps if needed)
12. Gears or pulleys
13. Procedure Sheet or Grid Planning Sheet

If you don’t have the materials to construct a solar car, you can order a kit from MiniScience.com. It is available both as a single pack and class pack. Kit content may be different from the images shown in this page.

Results of Experiment (Observation):

Experiments are often done in series. A series of experiments can be done by changing one variable a different amount each time. A series of experiments is made up of separate experimental “runs.” During each run you make a measurement of how much the variable affected the system under study. For each run, a different amount of change in the variable is used. This produces a different amount of response in the system. You measure this response, or record data, in a table for this purpose. This is considered “raw data” since it has not been processed or interpreted yet. When raw data gets processed mathematically, for example, it becomes results.

Calculations:

If you do any calculations, write your calculations in this section of your report.

Summary of Results:

Summarize what happened. This can be in the form of a table of processed numerical data, or graphs. It could also be a written statement of what occurred during experiments.

It is from calculations using recorded data that tables and graphs are made. Studying tables and graphs, we can see trends that tell us how different variables cause our observations. Based on these trends, we can draw conclusions about the system under study. These conclusions help us confirm or deny our original hypothesis. Often, mathematical equations can be made from graphs. These equations allow us to predict how a change will affect the system without the need to do additional experiments. Advanced levels of experimental science rely heavily on graphical and mathematical analysis of data. At this level, science becomes even more interesting and powerful.

Conclusion:

Using the trends in your experimental data and your experimental observations, try to answer your original questions. Is your hypothesis correct? Now is the time to pull together what happened, and assess the experiments you did.

Related Questions & Answers:

What you have learned may allow you to answer other questions. Many questions are related. Several new questions may have occurred to you while doing experiments. You may now be able to understand or verify things that you discovered when gathering information for the project. Questions lead to more questions, which lead to additional hypothesis that need to be tested.

Possible Errors:

If you did not observe anything different than what happened with your control, the variable you changed may not affect the system you are investigating. If you did not observe a consistent, reproducible trend in your series of experimental runs there may be experimental errors affecting your results. The first thing to check is how you are making your measurements. Is the measurement method questionable or unreliable? Maybe you are reading a scale incorrectly, or maybe the measuring instrument is working erratically.

If you determine that experimental errors are influencing your results, carefully rethink the design of your experiments. Review each step of the procedure to find sources of potential errors. If possible, have a scientist review the procedure with you. Sometimes the designer of an experiment can miss the obvious.

References:

List your references in this section of your report.