An easy test...

[iacob alex]

  ...can be made,after you watch carefully a short movie on   youtube.com  ,more exactly at: 
     http://www.youtube.com/watch?v=hl8dM2wQBk&feature=related

    It's a classic design in the old manner of the "old PM folklore"...

    Now let's simplify it,so to use the "essence idea" :

     -take only one simple hinged arm (spoke)

     -move the rotating axle of the hub...not having,this time the axis placed centrally,so to get a "self pulsatory lever" equivalent (fixed arm/eccentric hub vs. pulsatory arm/simple hinged mass).

    If you like ,take this  as a "flapping fish" in two "surroundings"(gravity flow and rotational inertia).

    It can be a simple mobile "toy" ...or maybe more...

        All the best! / Alex

[iacob alex]

   ...sorry about the wrong address...

   So,try again at:   http://www.youtube.com/watch?v=hl8dM2wQB4k&feature=related

       All the best ! /Alex