Endurance (aircraft)

In aviation, Endurance is the maximum length of time that an aircraft can spend in cruising flight. Endurance is sometimes erroneously equated with range. The two concepts are distinctly different: range is a measure of "distance flown" while endurance is a measure of "time spent in the air". For example, a typical sailplane exhibits high endurance characteristics but poor range characteristics.

Endurance can be written as:

$E=int\_\{t\_1\}^\{t\_2\}dt=int\_\{W\_1\}^\{W\_2\}-frac\{dW\}\{F\}=int\_\{W\_2\}^\{W\_1\}frac\{dW\}\{F\}$

where W stands for fuel weight, F for fuel flow, t for time.

Endurance can factor into aviation design in a number of ways. Some aircraft, such as the P-3 Orion or U-2 spyplane, require high endurance characteristics as part of their mission profile (often referred to as loiter time (on target)). Endurance, like range, is also related to fuel efficiency; fuel efficient aircraft will tend to exhibit good endurance characteristics.