Actually the blades have nothing to do with lifting the mower.The mower is a powered rotary push lawn mower that use an impeller above the spinning blades to drive air downwards creating an air cushion that lifts the mower above the ground.
The downside to the mower is that it's usability in rough terrain or on the edges of lawns as the lifting air-cushion is destroyed by wide gaps and holes between the chassis and the ground.
They were basically built to operate on steep slopes, waterfronts or around ponds and high-weeded areas, not to cut lawns and they do a poor job of that. The quality of cut is far inferior to that of a regular rotary mower because the grass is pushed away from the blade by the impeller building the cushion of air that it rides on.