.....of air , with an oscillating cylinder , at : http://www.mechlabs.in/articles/building-an-compressed-air-engine-concept (http://www.mechlabs.in/articles/building-an-compressed-air-engine-concept)
...has something in common , with playing gravity unbalance (fall...)/"self-compression"/, with an oscillating lever (age) , at :
www.youtube.com/watch?v=Upp-Xr5JAg0 (http://www.youtube.com/watch?v=Upp-Xr5JAg0) (if we make a "cut"...).
Al_ex
...this time due to rotational inertia ("centrifugal throwing") , at:
www.invention-conception.com/inertialpropulsion.php
It seems that ,generally speaking , the natural and artificial gravity , have a common application for a gravity motor and a space drive , if we use rotational effect.
Al_ex