JNTU
JNTU B.Tech III FLIGHT MECHANICS II Previous Question Paper (November/December - 2018 - R13)
Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit. Each question carries 10 marks.
Part A
What is the significance of trim curve?
Answer
The trim curve represents the equilibrium state of an aircraft where the sum of all moments about the center of gravity is zero. It is significant for determining the control surface deflections required to maintain steady flight at various speeds and altitudes, ensuring the aircraft remains stable and controllable.
Write about effect of flap and flight speed on force and moment coefficients.
Answer
Flap deflection increases the lift coefficient (CL) and produces a nose-down pitching moment (CM) due to the shift in the center of pressure. As flight speed increases, the dynamic pressure rises, requiring smaller control surface deflections to achieve the same force and moment changes, while aerodynamic coefficients generally remain constant in the linear range of the angle of attack.
What is significance of aerodynamic derivatives?
Answer
Sign in to view the complete answer paper.
Explain the function of differential aileron.
Answer
Sign in to view the complete answer paper.
What do you mean by aerodynamic balancing? Explain.
Answer
Sign in to view the complete answer paper.
Explain maneuver margin and their relation to static margin.
Answer
Sign in to view the complete answer paper.
Draw the system reference frame of earth to body axis for the flight vehicle.
Answer
Sign in to view the complete answer paper.
Explain with neat sketch about the Dutch roll phenomena.
Answer
Sign in to view the complete answer paper.
What do you mean by Phugoid motion? Discuss.
Answer
Sign in to view the complete answer paper.
Explain in brief about the phenomena of roll coupling.
Answer
Sign in to view the complete answer paper.
Part B
Explain the need for stability in airplanes with neat sketch of Cm vs CL graph.
Answer
Sign in to view the complete answer paper.
Derive an expression for the criterion for static longitudinal stability for an airplane with conventional wing-tail combination and draw the neat sketch.
Answer
Sign in to view the complete answer paper.
Explain pitch damping, control to trim and their relation to static margin with neat Cm Vs CL or alpha curve.
Answer
Sign in to view the complete answer paper.
What are the factors affecting the tail contribution? Describe them.
Answer
Sign in to view the complete answer paper.
Derive the relationship between elevator angle for trim and total lift coefficient.
Answer
Sign in to view the complete answer paper.
Explain in brief about asymmetric power and adverse yaw with neat sketch.
Answer
Sign in to view the complete answer paper.
Explain about Static Margin and derive an expression of dCm/dCL for stick fixed condition with neat sketches.
Answer
Sign in to view the complete answer paper.
Explain with neat sketch the effect of pitching velocity on tail incidence.
Answer
Sign in to view the complete answer paper.
Derive the relationship between elevator angle for trim and total lift coefficient.
Answer
Sign in to view the complete answer paper.
Consider an aircraft taking a turn in flight, Justify the statement- "Aerodynamic forces and moments acting on the aircraft due to roll and yaw".
Answer
Sign in to view the complete answer paper.
Derive an expression for relationship between stick-fixed and stick-free static stability.
Answer
Sign in to view the complete answer paper.
Discuss the phenomena of weather cock stability with neat sketches.
Answer
Sign in to view the complete answer paper.
Write the Equation of motion in perturbation variables. State the assumptions of small perturbations.
Answer
Sign in to view the complete answer paper.
Explain decoupling of equations of motion of the aircraft by mentioning the conditions for its validity.
Answer
Sign in to view the complete answer paper.
Explain the concept of solution of the stability quartic in dynamic stability.
Answer
Sign in to view the complete answer paper.
Explain about the modes of stability with suitable examples.
Answer
Sign in to view the complete answer paper.
An aircraft has a mass of 20000kg and wing area of 50m2. It is flying at 240m/s at an altitude having sigma = 0.5 and the stability quadratic equation is given as lambda^4 + 7.7lambda^3 + 9.3lambda^2 + 13.2lambda + 0.28 = 0. Find the period of motion and time to half the amplitude.
Answer
Sign in to view the complete answer paper.
Justify the statement that in longitudinal dynamic stability "The sideways velocity and the angular velocities in roll and yaw are always zero".
Answer
Sign in to view the complete answer paper.
The statically stable aircraft may be dynamically stable or unstable. Similarly "dynamically stable aircraft may be statically stable or unstable". Are both statements true? Justify.
Answer
Sign in to view the complete answer paper.