And the diagram does not show a prop or spinner. I assume your 'large plastic disk' is the spinner backplate. This goes behind the prop. A heavy steel washer goes in fron of the prop, along with the prop nut. Then the spinner cone goes in front of all that.

I have abandoned the use of spinners, and have gone over to spinner nuts on most of my planes:

http://www3.towerhobbies.com/cgi-bin...?&I=LXE158&P=0

They make it easier to change props, and they don't get chewed up by the starter.