The solar thermal motor operates by using bands of stretched black plastic bag
to continually pull a flywheel off-center as it rotates on an axle.
The strips are heated by sunlight on one side of a flywheel assembly,
pulling the flywheel toward the sun-side. As the strips rotate to the back,
they cool in the shadow of the drum and relax.
This makes the flywheel continuously off-center on the sun side,
causing it to rotate.