Question

An aircraft has a minimum sink rate of \(1.5\ \text{m/s}\). If it starts gliding from an altitude of \(1800\) metres, what is its maximum endurance (loiter time) in minutes?

• A. 22 minutes
• B. 20 minutes
• C. 28 minutes
• D. 30 minutes

Hint:

For a gliding aircraft, \[ \boxed{ \text{Maximum Endurance} = \frac{\text{Altitude}}{\text{Minimum Sink Rate}}. } \] Minimum sink speed provides the longest time aloft.

Answer 1

The Correct Option is B

Step 1: Use the relation for endurance during glide. The maximum endurance is given by \[ \boxed{ \text{Endurance} = \frac{\text{Altitude}}{\text{Minimum Sink Rate}}. } \]

Step 2: Substitute the given values. Given, \[ \text{Altitude}=1800\ \text{m}, \] \[ \text{Minimum Sink Rate}=1.5\ \text{m/s}. \] Hence, \[ \text{Endurance} = \frac{1800}{1.5} = 1200\ \text{s}. \] Converting into minutes, \[ 1200\div60=20\ \text{minutes}. \] Therefore, \[ \boxed{20\ \text{minutes}} \] is the correct answer. Thus, \[ \boxed{(B)} \] is the correct answer.