A helicopter operating with limited power, the speed giving the steepest or maximum angle of climb…

(Limited power: Power available is less than the hover power required)

Refer to figure. **1.** Where the greatest difference between power required and power available (maximum power margin) occurs at the lowest point (bottom) of the power required curve **(Point 1)**, the corresponding speed is the Minimum Power Airspeed (V_{MP}).

Also, at the lowest point of the power required curve, the fuel consumption is at its minimum. Thus, the maximum endurance can be achieved, and the corresponding speed is the V_{MAX END}.

Therefore, the V_{Y} is also V_{MP} and V_{MAX END}.

**2.** At the tangent of the origin to the power required curve **(Point 3)**, the maximum range speed, V_{MR}, is found, which is also the minimum angle of descent speed and the minimum drag speed, V_{MD}, (Best Rotor thrust / Rotor drag ratio).

**3.** On the power required curve, at the tangent from the power available line at the vertical axis (0 kt) **(Point 4)**, the best angle of climb speed, V_{X}, is found. It is the speed which gives the steepest climb angle to clear obstructions.

The question is referring to the best angle of climb which is Vx therefore, it ** will always be less than the endurance speed**.

Your Notes (not visible to others)

This question has appeared on the real examination, you can find the related countries below.