Discussion
For \( C_{l_p} = -0.45 \), \( \bar q = 3000 \ \mathrm{Pa} \), \( S = 25 \ \mathrm{m^2} \), \( b = 12 \ \mathrm{m} \), \( V = 120 \ \mathrm{m/s} \) and \( I_{xx} = 30\,000 \ \mathrm{kg\,m^2} \), the dimensional \( L_p = C_{l_p}\bar q S b^{2}/(2VI_{xx}) \) is about
Answer: D
Assembling the conversion:
\[ \begin{aligned} \bar q S b^{2} &= 3000 \times 25 \times 144 \\ &= 1.08 \times 10^{7} \\ 2VI_{xx} &= 7.2 \times 10^{6} \\ L_p &= -0.45 \times 1.5 = -0.68 \ \mathrm{s^{-1}} \end{aligned} \]
so -0.68 per second, giving a roll time constant of about 1.5 seconds. -1.35 omits the factor of two in the normalisation, which doubles every rate derivative and is the classic error here. -0.45 is the coefficient itself, dimensionless and unusable in the equations of motion. -0.07 slips a decade.
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