The following design works quite well on a smooth floor and is easy enough for a child to make; it works like a catherine wheel. It has no bearings and large wheels so there is very little friction, it should weigh about 12 gm.
It is a bit difficult to insert two balloons at once, they should be inflated to the same size or it tips over.
It is a bit like the rotodyne.
Read about the Great Panjandrum (article no. 10).
This is a preliminary exercise
It can be made out of almost anything, eg a sweet wrapper; aluminium foil is good. It can be made without sellotape even but you must have a drinking straw and some means of making a hole in it. If you make them one-ended they sound like a steam train. You can make several on one straw, different types, different directions etc. Attach one to a hat with a bendy straw to blow through.
This one works a lot better
this one goes round & round on the spot (no balloon in picture)
detail of motor
the flange reduces the rolling resistance quite a lot
This one comes towards you as you blow it away from you through a hand-held straw
it will even go slightly uphill
bottle jet car
my email is email@example.com
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