Lighter Than Air

By: Alex
School: Sally Ride Elementary
Grade: 5th

Hello! I am Alex. I am a 5th grader gifted/magnet student at Sally Ride. I am very excited to participate in the Junior Solar Sprint Competition, representing my school. This is my first time here and I am learning a lot about solar energy usage, designing, and construction of solar cars.

About My Solar Car

When creating my solar car, I had several ideas in mind:
1. to make the chassis entirely out of wood
2. to make the car as lightweight as possible
3. to include some materials that were previously used.

My STEM teacher supplied the materials, like the balsa wood and solar panel
Cutting the wood wasn’t hard because it was very soft, so I could use scissors. I assemble the car like I can do a kite. I wanted it to be light and I did it!

Materials I used for the car is:

  • Balsa Wood
  • Wooden Skewers (Axels and Solar Panel support)
  • Hot Glue
  • Plastic Wheels and Gears (1:4 gear ratio)
  • Motor
  • Tape
  • Battery Pack
  • Binder Spine (Guide for the car)

How Much Weight Did I Save Exactly?

The original balsa wooden board I used was 27 cm x 10 cm x 0.5 cm
The chassis is made out of 2 types of sticks:
• 27 cm x 1 cm x 0.5 cm (long stick)
• 10 cm x 1 cm x 0.5 cm (short stick)
Each stick has 3 notches in them so they slot together, similar to Lincoln Logs.
The volume of the original balsa board is 27cm x 10 cm x 0.5 cm = 135 cm^3
The volume of the “long stick” is 27 x 1 x 0.5 =13.5 cm^3
The volume of the “short stick” is 10 cm x 1 cm x 0.5 cm = 5 cm^3
Because there are 3 of each stick, we need to multiply each volume of the sticks by 3.
13.5 x 3 = 40.5
3 x 5 = 15
to find the total amount of balsa wood used, we now have to add both 15 and 40.5
40.5 + 15 = 55.5
135 – 55.5 = 79.5
79.5 + 10.75 = 90.25
(10.75 is extra balsa wood used for supporting the solar panel and motor)
The volume of the orginal balsa wood board is 27cm x 10cm x 0.5cm = 135cm^3
135 – 90.25 = 44.75
44.75 cm^3 of balsa wood was saved

The weight of the car is 202 grams (without AA batteries)
The weight of the standard solar car (metal rods, Energy Whiz solar car set, 27 cm x 10 cm x 0.5 cm balsa wood board, etc.) is around 290 – 280 grams (without AA batteries
280 g – 202 g – 78 g
78 grams saved on weight

What is the Speed of My Car?

The car ran reached 20 meters in 6 seconds. Its speed can be expressed as 12 Kilometers per hour!

This project and its content has been approved by Ms. Berriz.

11 thoughts on “Lighter Than Air

  • Super speedy! It looks like you got the wheels to turn as fast as the motor goes, must be pretty light on weight!

  • Excellent time for 20 meters. !!! very good selection of lightweight materials. Congratulations to that future Formula 1 engineer.

  • I like that you used Math to demonstrate how you lessened the car’s weight. I’m sure that helped increase its speed. Great run, so congratulations and good luck!

  • Lighter than air indeed! Way to go Alex! What a great attention to detail in your build and explanation. Congratulations!

  • You are the future minds! By creating this solar car you are learning how to reduce the CO2 emissions. You definitely, accomplished your goal by making this car with high speed! Congratulations!!!

  • Alex I am proud to be your teacher! Great job utilizing your math skills to provide evidence and rationale for your design choices!

  • Solar cars are some of the inventions that will help us to mitigate climate change. Well done!

  • 20 minutes in 6 seconds!! way to go! Great planning and computational skills to come up with an outstanding design!!

  • This was a very cool concept car that you made; especially since solar cars and electric cars are so popular right now. I’m very impressed that you were able to build such a light-weight and fast car and the math you did to figure out the weight saved and speed was also quite impressive. Great job on this project!


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