Nodal precession is the precession of an orbital plane around the rotation axis of an astronomical body such as Earth. This precession is due to the
Lead is the axial advance of a helix or screw during one complete turn (360°). The lead for a screw thread is the axial travel for a single revolution.
Flattening - 1st variant
Flattening is a measure of the compression of a circle or sphere along a diameter to form an ellipse or an ellipsoid of revolution (spheroid) respectively.
Turbine specific speed
The specific speed value (radian/second) for a turbine is the speed of a geometrically similar turbine which would produce one unit of the specific speed