Discussion
Regarding the horizontal tail of a conventional airplane, which one of the following statements is true?
Answer: A
The horizontal tail contributes to \(C_{m_{\alpha}} \lt 0\).
Static longitudinal stability requires the pitching moment coefficient to fall as angle of attack rises (\(C_{m_{\alpha}} \lt 0\)), so that a nose-up disturbance produces a nose-down restoring moment. A tail behind the centre of gravity gains lift when the angle of attack increases, and because it acts on a long moment arm aft of the c.g., that lift produces a nose-down moment. This is the main stabilising contribution in a conventional airplane.
The tail does not make \(C_{m_{\alpha}}\) zero (neutral stability) or positive (unstable); those would describe an aircraft without adequate tail volume. The tail is usually set to give a positive \(C_{m0}\) for trim, but paired with a positive \(C_{m_{\alpha}}\) that option describes an unstable airplane.
Post your comment
Please log in or register to post a comment.
Examination Categories
- SSC Exams
- Banking Exams
- Teaching Exams
- Civil Services Exams
- Railways Exams
- Engineering Recruitment Exams
- Defence Exams
- State Government Exams
- Police Exams
- Insurance Exams
- Nursing Exams
- Other Government Exams
- NRA CET
- PG Entrance Exams
- Campus Placement
- MBA Entrance Exams
- CUET and UG Entrance
- Judiciary Exams
- Regulatory Body Exams
- Software Development