In flight mechanics, the “thrust acting on the disc” refers to the total force exerted by the propeller or rotor on the surrounding air as it accelerates the air in the downward direction to generate lift or propulsion. This concept is particularly relevant for propellers and helicopters or other rotary-wing aircraft.
T = Thrust generated by the aircraft or airfoil A = Area of the airfoil or wing perpendicular to the flow direction Δp = Change in momentum of the air or pressure