A helium balloon with a little remote control car in it. It has little hinged paddles glued around the horizontal axis that fully extend due to gravity when at the bottom of the balloon and fold out of the way when they're at the top.

As the car rolls, the balloon under it spins, the bottom paddle extends and pushes the air moving the entire unit. When it rotates around to the top heading into the airstream, it folds out of the way so it doesn't negate the push of the paddles on the bottom. (see illustration link)

I think you might even be able to steer it with the little car's front wheels since when you turn the car's front wheels, the axis would tilt making the bottom driver paddle push to the side as well as back. The centrifugal force of the relatively heavy paddles around the perimeter would act to stabilize the unit as well.

It could also be called a paddlewheel balloon.
-- doctorremulac3, Mar 27 2014

Simple remote control balloon https://www.dropbox...loon-O-Stat%202.jpg
Turn the car left, it goes right but other than that the forward and reverse are the same for the car and the balloon. [doctorremulac3, Mar 27 2014]

Next step would be to adapt this to the screw propulsion model, as opposed to the paddle wheel. (Just going by apparent similarities here between Brunel's propulsion system, and the one that replaced it, for ships.)

I'll grant the modification could get ugly or complicated (which is often another word for ugly).
-- skoomphemph, Mar 27 2014


Now that I think of it, this should be called a paddle wheel balloon.
-- doctorremulac3, Mar 27 2014


You'd want to add a inductive charger to the little car in the baloon, so that you wouldn't have to remove it to recharge it every 10 min or so. A nearly transparent baloon would be a plus so you could see which way the car was pointing. That problem aside, sounds like cheap and easy fun, the folding paddles being the hardest part of the build.
-- CraigD, Apr 04 2014



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