Abstract: A rotary distributor head for a sprinkler is disclosed. In a particular embodiment, the head includes a stack of deflector pads axially aligned. The head also includes a plurality of distribution channels radially disposed on at least one deflector pad that are configured to distribute a stream of water over a surrounding area. A plurality of spiral grooves is disposed on at least one deflector pad that are configured to cause the head to rotate when the water is flowing through the grooves. In addition, the head includes an orifice on each upstream deflector pad configured to pass a portion of the stream of water through to an adjacent downstream deflector pad. The head controls a rotational speed while increasing the uniform wetted footprint of instantaneous impact under a range of operating pressures and flow rates.