JNTU
JNTU B.Tech III AIRCRAFT PERFORMANCE AND STABILITY Previous Question Paper (January/February - 2023 - R18)
Note: i) Question paper consists of Part A, Part B.
ii) Part A is compulsory, which carries 25 marks. In Part A, Answer all questions.
iii) In Part B, Answer any one question from each unit. Each question carries 10 marks and may have a, b as sub questions.
PART – A
(25 Marks)
What are the different types of drag acting on an airplane?
Answer
The total drag acting on an airplane is primarily categorized into two main types: parasite drag and induced drag. Parasite drag is caused by the friction and pressure differences resulting from the aircraft moving through the air, including skin friction, form drag, and interference drag. Induced drag is the byproduct of lift generation, resulting from the formation of wingtip vortices as high-pressure air beneath the wing flows toward the low-pressure region above the wingtip.
What are the different types of airspeed?
Answer
There are four primary types of airspeed used in aviation:
- Indicated Airspeed (IAS): The speed read directly from the airspeed indicator, which measures the difference between pitot (total) pressure and static pressure without accounting for instrument or position errors.
- Calibrated Airspeed (CAS): Indicated airspeed corrected for instrument installation and position errors.
- Equivalent Airspeed (EAS): Calibrated airspeed corrected for adiabatic compressible flow at a specific altitude. It is the speed at which the aircraft experiences the same dynamic pressure as it would at sea level.
- True Airspeed (TAS): The actual speed of the aircraft relative to the undisturbed air mass, obtained by correcting equivalent airspeed for non-standard air density.
Define drag polar. Write expression and plot the graph.
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Explain in brief about the different methods of drag reduction in an aircraft.
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What do you mean by specific air range?
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With the help of graph, explain about absolute ceiling and service ceiling?
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What do you mean by wing loading and load factor?
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How excess power is affecting the aircraft performance? Draw graph.
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What do you understand by trip fuel and tankering?
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What are the different types of air safety procedures and requirement during landing?
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PART – B
(50 Marks)
Explain in brief about the mission profile with neat sketches. Mention all the stages.
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Explain with the help of diagrams how the lift characteristics of a plain, cambered airfoil can be modified by leading edge and trailing edge flaps.
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Discuss aircraft force system needed for formulating the performance equations of motion.
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With the help of neat graphs, explain the variation of pressure, temperature and density with increase in altitude.
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Derive an expression of coefficient of pitching moment on an aerofoil at a distance ‘x’ from the leading edge.
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What is drag divergence Mach number? Discuss about various streamlined and bluff bodies in brief.
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Explain in brief about the Area Rule. Draw neat sketches.
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What are the different methods of thrust augmentation? Explain each.
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Derive an expression for minimum drag condition in a steady level flight.
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An aeroplane has a wing loading of 2400N/m2, and its drag equation is CD = 0.016 + 0.055 CL2, calculate its maximum lift/drag ratio, the minimum drag speed and the lift/drag ratio at a speed of 100m/s, E.A.S.
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A sailplane weighs 4500N and has a wing loading of 600 N/m2. Its drag equation is CD = 0.010 + 0.022 CL2. After completing a launch at 350m in still air, what is the greatest distance the sailplane can cover, and what is the greatest duration of flight possible, assuming in both cases flight over level ground? Find also the corresponding speeds of flight. Ignore changes of density of the atmosphere.
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Obtain an expression for turn radius and turn rate for maneuvering flight.
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An aeroplane having weight of 1500 kg is turning at a speed of 200 km/hr and bank angle of 50 deg. Obtain the centrifugal force, lift and radius of turn.
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Deduce an expression of pull up maneuver? Also draw neat diagram.
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An aircraft weighs 1500 kg and having a wing area of 2 m2, takes 18 sec for one full coordinate turn at sea level. If CL during turn is 1.1 and CD is given by CD = 0.0175 + CL2. Find aircraft bank angle and thrust required during turn.
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Describe the phases of descending flight through a diagram and discuss the estimation of landing distances.
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What are the important parameters to be considered for the flight planning and safety?
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An aeroplane has a constant Thrust to Weight (T/W) ratio of 0.25 and braking friction coefficient of 0.5 while take-off on an 850 m strip not yet airborne, the engine fails. At that instant the plane had attained a speed of 69 knots. The pilot immediately applies brake. Will the plane stop before the end of the runway (neglect aerodynamic drag) Justify your answer.
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