maximum gradient speed

best angle-of-climb speed (Vx)

best angle-of-climb speed (Vx)click for a larger image
The air speed at which an aircraft will gain the greatest amount of altitude for a given distance. It is less than the best rate of climb speed, and its usual value is about 1.2 times the basic stalling speed. The climb is usually carried out at high-power and only for sufficient time to clear obstacles encountered in flight. In aircraft with reciprocating engines, the lower speeds lead to less cooling and consequently higher engine temperatures. This speed is determined by actual flying trials. Also called maximum gradient speed and occasionally confused with takeoff obstacle clearance speed.
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