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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)

  • A

    Decreases as altitude increases.

  • B

    Is always less than the best endurance speed.

  • C

    Is always equal to the best rate of climb speed.

  • D

    Is always equal to the best endurance speed.

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 (VMP).

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 VMAX END.

Therefore, the VY is also VMP and VMAX END.

2. At the tangent of the origin to the power required curve (Point 3), the maximum range speed, VMR, is found, which is also the minimum angle of descent speed and the minimum drag speed, VMD, (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, VX, 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.

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