Fonctionnement - Pet-Star water rocket car

Fill about half of the bottle with water (the exact relationship between air and water can obviously be optimized).

Screw the cap on the bottle.

Connect the tube with the bicycle valve to the bigger tube.

Pump the air in the bottle with a bicycle pump.

As soon as the pipes separate the car moves forward.

Do not use an electric compressor (max. 8 bar)...

To test your rocket find an open area (min. 50 metres). Warn everyone around before launch.

This video shows the winning car in the 2007 competition. The car travelled nearly 78 metres, following a very straight line.