FAA Private Pilot Helicopter (PRH)Performance and LimitationsEasy
A helicopter's power-required curve is plotted against airspeed. The lowest point on this curve occurs at 60 KIAS. Flying at this airspeed provides the helicopter's:
- ANever-exceed speed (Vne)
- BMaximum range
- CBest rate of climb (Vy)
- DMaximum endurance
Show answer & explanationAnswer & explanation
Correct answer: D. Maximum endurance
The lowest point on the power-required curve is the airspeed that requires the least power to maintain level flight. Because it uses the least fuel per unit of time, this airspeed gives maximum endurance, not maximum range (which requires the best power-to-airspeed ratio) or best climb.
Why the other options are wrong
- A. Vne is a structural airspeed limit unrelated to the power curve's shape.
- B. Maximum range comes from the airspeed with the best ratio of speed to power, found by a tangent line from the origin, not the curve's minimum point.
- C. Vy is related to excess power available, not simply minimum power required.
Power-Required Curve
A graph showing the power needed to maintain level flight at various airspeeds; its lowest point identifies the maximum endurance airspeed.
- Bottom of curve = minimum power required = best endurance
- Tangent from origin to curve = best range airspeed
- Curve rises again at high speed due to increasing parasite drag
Memory trick: Bottom of the bowl = longest time in the air (endurance)