JNTU
JNTU B.Tech III FLIGHT MECHANICS II Previous Question Paper (November/December - 2017 - 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 and may have a, b, c as sub questions.
Part A
Distinguish between equilibrium and stability of an aircraft.
Answer
Equilibrium refers to a state where the sum of all forces and moments acting on the aircraft is zero, meaning the aircraft maintains a constant flight path and attitude. Stability refers to the tendency of an aircraft to return to its original equilibrium state after being subjected to a small disturbance.
What is stick-fixed neutral point of an aircraft?
Answer
The stick-fixed neutral point is the center of gravity location at which the aircraft's longitudinal static stability is neutral (i.e., the aerodynamic center of the complete aircraft). At this point, the pitching moment coefficient with respect to the angle of attack is zero, meaning the aircraft has no inherent tendency to return to or depart from its trimmed angle of attack.
Explain two aerodynamic and two stability derivatives that influence the stability of an aircraft flying in the pitch plane.
Answer
Sign in to view the complete answer paper.
Explain the derivatives of axial and normal force components and pitching moment with respect to flight speed and angle of attack.
Answer
Sign in to view the complete answer paper.
Define elevator hinge moment.
Answer
Sign in to view the complete answer paper.
Define lateral – directional stability.
Answer
Sign in to view the complete answer paper.
Define Euler angles.
Answer
Sign in to view the complete answer paper.
Derive an expression for the angular momentum of a body.
Answer
Sign in to view the complete answer paper.
Define the term ‘time constant’ of a first order system.
Answer
Sign in to view the complete answer paper.
Describe phugoid mode of flight.
Answer
Sign in to view the complete answer paper.
Part B
a) Show in a diagram and explain all the forces and moments acting on an aircraft moving in the pitch plane.
b) Derive an expression for the longitudinal static stability, equilibrium lift coefficient, and statutory limits on static margin.
Answer
Sign in to view the complete answer paper.
a) Define load factor. Derive an expression for the pitch rate of an aircraft in a turn manoeuvre in a horizontal plane in terms of the load factor.
b) Derive an expression for elevator angle required in a turn, where delta is elevator angle and n is the load factor.
Answer
Sign in to view the complete answer paper.
a) What are the components of the aircraft that contribute to the pitching moment of an aircraft? How do they vary with the geometric and flight parameters of the aircraft?
b) Explain the stability derivatives that influence the roll of an aircraft.
Answer
Sign in to view the complete answer paper.
Following Munk’s method, estimate the variation of the pitching moment of an aircraft with angle of attack for the given correction factors and average fuselage widths.
Answer
Sign in to view the complete answer paper.
a) Derive an expression for the parameter where Cm and CL are the pitch moment and lift force coefficients.
b) Derive an expression for the stick force of an aircraft in pitch manoeuvre.
Answer
Sign in to view the complete answer paper.
a) Derive an expression for the stick force gradient, variation of the stick force with the speed of the aircraft in an unaccelerated flight.
b) Define equilibrium lift coefficient. Derive an expression for the rate of change of elevator angle with equilibrium lift coefficient.
Answer
Sign in to view the complete answer paper.
Derive the equations of motion of a rigid body.
Answer
Sign in to view the complete answer paper.
a) An aircraft flying north east is climbing at a speed of 200 kmph at 45 degree to horizontal. Analyze the kinematics.
b) An aircraft has a lift curve slope of 0.15 per degree and the rate of change of pitching moment with angle of attack is -1.8 per radian. What is the static margin?
Answer
Sign in to view the complete answer paper.
a) Given the transfer function determine the roll angle of the aircraft.
b) Explain short period mode of an aircraft.
Answer
Sign in to view the complete answer paper.
State the linearized equations of motion of a rigid body and derive the linearized equations of motion of an aircraft.
Answer
Sign in to view the complete answer paper.