The first work on the calculation of rotor airloads in forward flight is published
Wednesday, January 31, 1962
The paper by Miller was the first to attempt to model the effects of the rotor wake (both shed and trailed) in the calculation of oscillatory airloads in forward flight.
Miller, R. H.: Rotor Blade Harmonic Air Loading. IAS Paper No. 62-82, Jan. 1962.
Source: "Milestones in Rotorcraft Aeromechanics", Johnson W., , NASA/TP-2011-25971, May 2011, Page 17