the view from an alternate universe: FAA in USA
How interesting! In 50 years of flying FAA-certified aircraft using FAA-generated aeronautical theory texts, up to Aerodynamics for Naval Aviators (US Navy), I had never been exposed to thrust as an ingredient to Vx!
I believe (as a former FAA Designated Examiner) that in this corner of the globe, THRUST is not mentioned! All explanations of Vx are based on the POWER-required curve, Vx being found at the minimum-power-required (top of polar curve) speed, Vy being found at the point of tangency of a line from origin to polar curve. Similarly in Gliders (minimum sink vs best L/D).
Add this conundrum to the fact that French helicopter rotors revolve in the opposite direction to USA helicopter rotors. Vive la difference!
Dave
ATP CFI ASMELIGH