Refer to figure.

The power required curve can be described as a fuel flow curve. Where the power required is high, fuel flow is high:

**1. At the bottom of the power required curve **(Point 1), the power required is at a minimum and fuel flow will be at a minimum as well.

__, which is also the maximum endurance speed, V__

**The corresponding TAS is the minimum power required speed, V**_{MP}_{MAXEND }and best RoC speed, V

_{Y}.

**2. At the intersection between the power available and power required curves** (Point 2), where the power margin is zero, since no further power is availbale to accelerate the helicopter in level flight, **the V _{MAX} is found**. It is the highest sustainable speed (subject to V

_{NE}) while flying straight and level.

**3. 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**(Best Rotor thrust / Rotor drad ratio).

_{MD }**4.** 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.

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