I am reading Cat A heli procedures, and there is Vtoss speed, so what is the difference between Vx(best angle of climb speed) and Vtoss(take off safety speed) ?
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$\begingroup$ Related: How a takeoff decision point (TDP) for vertical takeoff vehicle is defined? $\endgroup$– minsCommented Sep 22, 2023 at 17:44
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1 Answer
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Vx is the best angle of climb speed, with all engines operating. Helicopters can climb vertically in some situations, in which case their airspeed is zero, so Vx is zero. Vx increases above zero for certain loading and density altitude when the helicopter loses the ability to climb vertically.
Vtoss is the minimum airspeed at which a helicopter can maintain a climb if its most critical engine fails. An engine failure below this airspeed will cause the helicopter to begin to lose altitude until its airspeed increases above Vtoss or it hits the ground.
