.....at : http://www.youtube.com/watch?v=sbuGCgc-JCM (http://www.youtube.com/watch?v=sbuGCgc-JCM) (see from 0:08 to 0:20 ) , can be developed as a simplified flying device.
.....at : http://www.youtube.com/watch?v=uGBANgbRkws (http://www.youtube.com/watch?v=uGBANgbRkws) (see from 0:30 to 0:38) , can be a manner to imagine a simplified self-running gravity powered device.
Al_ex