Which three speeds are effectively the same for a jet aircraft?

In the context of jet aircraft performance, best angle of climb, minimum drag, and endurance speeds are closely related because they all focus on optimizing certain aerodynamic and performance characteristics of the aircraft.

Best angle of climb speed is the speed that allows the aircraft to gain the most altitude for the least horizontal distance. This is crucial during takeoff and initial climb phases. At this speed, the lift-to-drag ratio is optimized, allowing for maximum height gain.

Minimum drag speed is the speed at which the aircraft experiences the least aerodynamic drag. This speed is often related to the stall speed and is where the aircraft can maximize its performance without excessive energy loss due to drag.

Endurance speed, on the other hand, is the speed that maximizes the time an aircraft can stay aloft for a given amount of fuel. It typically occurs at a lower speed where fuel consumption is minimized. The relationship among these three speeds is significant because flying at best angle of climb speed or minimum drag speed can influence the overall endurance of the flight, especially in various phases like takeoff and climb.

Understanding that these speeds share a common aerodynamic performance aspect helps clarify why choosing them together is appropriate, as they are all critical parameters used to optimize flight performance during specific flight regimes.