I have a walk behind gas lawnmower with a belt drive. Love it.
However I dislike it for often clogging with grass and I dislike
having to empty the rear bag every 10 minutes or so. My solution is
to use a crossbar to prop the rear chute cover partly open whereby it
discharges the grass out and downward back onto the lawn. That way I
can make an uninterrupted pass to cut the grass until the gas tank
empties. My lawn size is two tanks of gas and 2 plus hours of work. I
leave the grass to dry for a few days, rake them and it fills around
9 large garbage bags. Its a lot of work for one guy my age.

I am thinking of modifying a lawnmower blade so that it functions as a
propeller type device to pick up the dried cut grass and fling them
into the rear bagger. My current idea is to bolt or rivet a backward
pitched paddle on the upper side of the blade. It will work (?) like
the impeller in a vacuum motor. Has anyone done this before? Any
other suggestions as to making such a modification?