Question

For a conventional airplane in straight, level, constant velocity flight condition, which of the following condition(s) is/are possible on Euler angles (\(\phi, \theta, \psi\)), angle of attack (\(\alpha\)) and the sideslip angle (\(\beta\))?

• A. \(\phi = 0^\circ, \theta = 2^\circ, \psi = 0^\circ, \alpha = 2^\circ, \beta = 0^\circ\)
• B. \(\phi = 5^\circ, \theta = 0^\circ, \psi = 0^\circ, \alpha = 2^\circ, \beta = 0^\circ\)
• C. \(\phi = 0^\circ, \theta = 3^\circ, \psi = 0^\circ, \alpha = 3^\circ, \beta = 5^\circ\)
• D. \(\phi = 0^\circ, \theta = 5^\circ, \psi = 0^\circ, \alpha = 2^\circ, \beta = 5^\circ\)

Hint:

In steady, straight, and level flight, roll and yaw angles are usually zero, with small values for the angle of attack and sideslip.

Answer 1

The Correct Option is A

Step 1: Understand Euler angles and flight conditions.
For a straight and level flight condition with constant velocity, the pitch angle \(\theta\) and roll angle \(\phi\) are typically small, and the yaw angle \(\psi\) is generally zero in the absence of sideslip. The angle of attack \(\alpha\) and sideslip \(\beta\) are generally small for steady flight conditions.
Step 2: Analyze each option.
Option (A): All conditions match the typical steady flight scenario, so it is correct.
Option (B): A roll angle \(\phi = 5^\circ\) is uncommon for straight, level flight.
Option (C): Yaw \(\psi = 5^\circ\) is not typical for straight, level flight.
Option (D): Similarly, a roll angle \(\phi = 5^\circ\) is not typically observed in steady flight.
Hence, the correct answer is (A).