Kid's corner

Make your own hybrid rocket!

Many good engineers and scientists are required to develop a rocket powerful enough to send satellites in space and accurate enough to put them on the right orbit. However, the principle on which they function is pretty simple, and you could make your own at home – with the help and supervision of your parents, of course!

How to proceed?

For this experiment, you will need:

  • A plastic bottle for the rocket body;
  • A cork that fits tightly the bottleneck of your plastic bottle;
  • A tube, cardboard or plastic, for the launcher;
  • Cling wrap;
  • White vinegar;
  • Baking soda;
  • The help and supervision of an adult.

Now be ready to launch your rocket in a few easy steps:

  1. Make sure your rocket-bottle fits into your launcher-tube. Put the launcher-tube in an outdoor area aiming for the sky. You can for example maintain it in position with logs. Well-designed rockets can fly up to 20 meters, so it’s important you launch it somewhere safe, away from buildings and people.
  2. Fill about a quarter of your bottle with vinegar. We suggest white vinegar because it is less messy but actually any vinegar will do.
  3. Put several large spoonful of baking soda on a square of cling wrap, fold the corners up, and twist it several times. This will be your time-release mechanism: once in the vinegar, the cling wrap will unravel slowly, allowing you to take cover before the rocket launch!
  4. From this step onwards, you will need to act fast!
  5. Put the cling wrap filled with baking soda inside your bottle. Try not to agitate it!
  6. Put the cork on the bottleneck.
  7. Place the bottle inside your launcher tube, aiming for the sky.
  8. Enjoy the show!

How does it work?

A hybrid rocket uses both solid and liquid fuel. In this case, the solid is the baking soda and the liquid is the vinegar. When the two are mixed, a chemical reaction takes place and forms two products: water and carbon dioxide. Carbon dioxide is a gas, and takes a lot more space than the solid baking soda or the liquid vinegar. The bottle is too small to contain it, so it pushes on the cork, harder and harder until… At some point, it pushes so hard that the cork cannot contain it anymore and… The rocket lifts off!

Schematically, the rocket engine developed during the HYPROGEO project works on the same principle: the reaction of a solid fuel and a liquid catalyst (see figure below). The chemical reaction also produces water and carbon dioxide. While on the Earth carbon dioxide contributes to the global warming through greenhouse effect, the rocket engine of HYPROGEO is meant to work in space, where carbon dioxide is harmless. Most importantly, neither water nor carbon dioxide are toxic. That’s why we call hybrid propulsion a green technology.

The similarity is striking between our home-made rocket and a hybrid propulsion engine! (Source: BBC)

You can make it better!

Like a real engineer, you can improve your rocket! Try to add fins to stabilize it, or a pointy nose to enhance its aerodynamics. You can also optimise the ratio of baking soda and vinegar, or improve your launcher. The only limit is your imagination!

Send us your best pictures or videos, and we will feature them on our website!

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