No, all projectors need a mount to hang them upside down. They all have 3 or 4 locations on the bottom to secure the mount. Plus, the mount gives you adjustability to center and align the image to screen.
If you MUST have it flush with the ceiling (and you haven't told us why), then the only option is open the ceiling and install a recess. As far as how down...you should consult the manual for that information. Every projector is just a bit different, if not more.
Originally Posted by qwerty11
Can you flush mount the hd20 without a separate mount? IE Is the projector itself mountable?