All aero planes with engines and all rockets depend on thrust. Thrust makes them move forward. They push large amount of air or other gases in one direction. This makes the aircraft fly in the other direction. Now you can see how thrust work in these experiments with balloons.
Things need :
o Long balloon
o Heavy paper
o Felt-tipped pens
Uncontrolled flight :
v Use felt-tipped pen to decorate the balloon as an aero plane if you like. It is easier to draw on the balloon if you blow it up first. Do not tie it shut. Tie it round a matchstick or a pencil.
v Cut wings from the heavy paper. Tape them to the Centre top of the plane.
v Remove the matchstick or pencil. Blow the balloon up as full as you can. Let it go. Thrust will make it fly around the room in a series of loops and turns until it runs out of air.