How to build a dry-ice-rocket / Mentos-Cola-rocket
Cut the upper part of a plastic bottle to form the top part of the rocket. The "combustion chamber" of the rocket will be made of an entire plastic bottle that you turn upside down.
Fix a washer on the outside bottom of the inner whole bottle.
Wrap dry ice around a magnet. Or in the case of the Mentos-Cola-rocket, glue the Mentos to the magnet.
By hitting the top of the rocket with a hammer, the magnet will lose bond with the washer and will fall into the water / cola.
Finally, the overpressure will cause the rocket to start off. Wings will stabilize the trajectory.
Fotos from my first model will follow as well as a video of the take off of my dry-ice-rocket.