In a propeller-driven airplane, when does maximum range occur?

• A. At maximum climb speed
• B. At constant speed and altitude
• C. At maximum lift/drag ratio
• D. At minimum fuel consumption

Answer: (C)

Maximum range for a propeller-driven airplane typically occurs at the point where the lift-to-drag ratio is maximized. This ratio represents the efficiency of the aircraft in generating lift relative to the drag it experiences. When the lift/drag ratio is at its peak, the airplane can cover the greatest horizontal distance for a given amount of fuel consumed.

At this point, the aircraft is optimally balancing the forces acting upon it and minimizing the energy lost to drag. Since endurance (time in the air) and range (distance traveled) are both impacted by fuel usage and aerodynamic efficiency, achieving the best lift/drag ratio directly contributes to maximizing range.

While other factors such as fuel consumption rates and operating speeds can influence range, it is the aerodynamic efficiency that fundamentally determines how far the aircraft can travel with that fuel.