Discussion
Statement I: The phugoid takes place at nearly constant angle of attack.
Statement II: In the phugoid the total energy of the aeroplane is exactly constant.
In the light of the above statements, choose the correct answer.
Answer: D
The first statement is the defining property of the mode. The second is nearly but not exactly true, and the difference is the whole reason the phugoid decays. Kinetic and potential energy trade back and forth almost losslessly, but drag removes energy on every cycle, and that slow leak is the damping. If total energy really were constant the motion would be undamped and the aeroplane would oscillate for ever. Lanchester's original idealisation did assume constant energy, which is why it predicts the period well and says nothing about the damping.
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