Flywheel & Displacer
The flywheel (shown upside down) provides momentum to bring the engine
through the full cycle. The attached foam displacer moves air back and
forth between the hot and cold chamber sections. The flywheel is made
of 1/8" thick 6061 aluminum. The short tab counterbalances the foam.
The flywheel has six spokes of which two are hidden by the foam. The
three pie shaped sections of the flywheel hidden by foam are filled
with foam. This prevents the outer foam sheets from flexing which would
reduce compression. The foam was cut with a hot wire to 1/8" sheets and
then scissor cut. The center hub is brass and press fits to the
flywheel. (Not shown is the latest variation which screws to the
flywheel with 3 screws.) The ends of the brass hub slip fit to ball
bearings. The thin crank shaft is 1/16" music wire (steel) press fit
into the brass. Hidden on the other side of the flywheel are two pieces
of tape for precision balance. Alternatives: the flywheel could be a
solid disk of thinner and lighter material however it must be flat to
avoid wobble.
