A cushion-less passenger seat. The passenger seat includes spaced left and right spreaders, each having a front and rear leg with top and bottom ends and a seating surface formed from a flexible bottom diaphragm attached to and extending between the left and right spreaders. The passenger seat also includes a lumbar support having lower and upper sections and front and back sides formed from a flexible diaphragm. The lower section of the lumbar support is attached to and between the left and right spreaders. The lumbar support upper section extends upwardly above the seat's rear legs and seating surface.