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anyone know how to make a self propelled "toy car" with out batteries or motors because i need it for tech class?

i need this info for a tech class one day project we're build and raceing cars out of a set amount of materials and it needs to be self proppelling also anything on making it aerodynamic would be appreciated.

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rickharris5 years ago
Rubber bands wound round the axle

Catapult fired along a fixed line (faster and more exciting.) Aero dynamics has more effect at speed.

Down hill! or so called gravity powered.

Falling water or sand if electricity is out I assume rockets are out as well.

here

here

here

cryptex (author)  rickharris5 years ago
sorry gravity and rockets are out
All brilliant options.
:-) Can you tell I have done this before?

Mouse trap as well. Watch fingers

reeaaalllly ?????

;-)

Steve
Rubber bands around the axle work well. Two things you can try are:

Stretch the rubber band before winding it around the axle to get more use out of the available length of the band.

Add something like a cone to your axle. Start wrapping the rubber band around the larger portion of the cone first. Having a larger radius will help with your acceleration because the band will tug on a larger moment arm. Then after a few wraps around the larger end of the cone, start winding it down to the skinny portion of the cone and then to the thinner axle. Once you have accelerated and are up to speed using the larger end of the cone, you can conserve the length of the rubber band in use when it is around the axle with a smaller radius.

I won a contest using this method a while back.

Let us know how it goes.
balloon