I'm hoping to make a small mechanical demo (~10cm tall) that models an orbit that is similar to the Earth-Moon orbit - that is, only one side of the Moon faces Earth. I'm trying to keep it simple, so here's my idea so far:
where the blue and yellow represent Earth and Moon, respectively. These are meant to represent a different planet and its moon though.
The orbit of the Planet (blue) and its Moon (yellow) has the following differences:
- Planet is eccentric
- Only one face of the Planet and see its Moon, i.e. the horizontal bar on each disc should remain parallel. The bars are for explanatory purposes only.
- Planet's rotation axis may shift (vertically along the green bar), but the Moon's orbital axis is fixed, i.e. Moon should be always in contact with the outer ring housing
My question is: how should the two discs be connected in order to to have the above properties? I've thought about using springs, but I think it'd be quite flimsy though.
I know about orreries, but typically they don't self-adjust orbits though. Also, I was hoping for a simpler mechanism given that there doesn't need to be empty space between the two discs. I'm only hoping to model the motion on just one plane.