Definition
A graph showing how much engine power an airplane needs to maintain level flight at each airspeed. The curve is U-shaped: power required is high at very slow speeds, drops to a minimum at a specific speed, then rises again as speed increases. The low point of the curve marks the airspeed at which the airplane flies most efficiently in terms of power.
Plain English
A chart that shows how much power the engine has to produce to keep the airplane flying level at any given speed. Both very slow flight and very fast flight need a lot of power; somewhere in the middle is the speed where the airplane needs the least.
Context Anchor
Seen in discussions of slow flight, elevator use, and why an airplane may need more power to hold altitude when it is flown slower.
Derivation
Curve comes from the Latin word curvus, meaning bent. That helps here because the line on the graph is not straight; it bends down to a low point and then rises again as speed changes.
Why Pilots Care
It reveals the airspeed for minimum power use and explains why power demand rises sharply at low speeds, directly affecting safety and efficiency decisions.
Grounding Statement
For each airspeed, the curve answers one practical question: how much power is needed to keep the airplane level?
Intuition Check
Do not read power required as the power you happen to have selected with the throttle. It means the power the airplane must have to maintain steady, level flight at that speed.
Example Sentence 1
The instructor pointed out that the airplane was operating on the back side of the power required curve and would need more throttle to maintain altitude, not less.
Example Sentence 2
Near the stall, the left side of the power required curve rises steeply, showing why more power is needed at very low airspeeds.