disk and the distant wake, we have: Combining equations, the disk loading is: The total pressure in the distant wake is: So the pressure change across the disk is equal to the disk loading. Above the disk the pressure change is: Below the disk, the pressure change is: The pressure along the slipstream is always falling downstream, except for the positive pressure jump across the disk. Power required From the momentum theory, thrust is: The induced velocity is: Where is the disk loading as before, and the power required in hover (in the ideal case) is: Therefore, the induced velocity can be expressed as: So, the induced velocity is inversely proportional to the power loading . Examples See also Wing loading References Aerospace engineering