Jawaharlal Nehru Technological University Hyderabad
Jawaharlal Nehru Technological University Hyderabad B.Tech II AIRCRAFT PERFORMANCE Previous Question Paper (March - 2022 - R16)
Answer any five questions. All questions carry equal marks.
Main
Write the relation between sea level gravity and gravity at flying. How these terms are related? Write the expression and explain.
Answer
The variation of gravitational acceleration with altitude is governed by Newton's law of universal gravitation. The relation between gravity at sea level (g0) and gravity at an altitude (h) is expressed as:
Where g0 is the acceleration due to gravity at sea level (approximately 9.80665 m/s2), R is the radius of the Earth (approximately 6371 km), and h is the altitude above sea level. As altitude increases, the distance from the center of the Earth increases, causing the gravitational force to decrease according to the inverse-square law. For most aircraft performance calculations within the troposphere, the variation is often considered negligible, and g is assumed to be constant; however, for high-altitude flight or orbital mechanics, this relationship is essential to account for the reduction in weight.
Derive expression for maximum lift to drag ratio (L/D). With respect to the coefficient of drag (CD,0) at zero angle of attack.
Answer
The drag polar for a typical aircraft is given by the equation:
where CD,0 is the zero-lift drag coefficient and K is the induced drag factor. The lift-to-drag ratio is defined as:
To find the maximum L/D, we differentiate the expression with respect to CL and set it to zero:
This implies CD = CL * (dCD/dCL). Since dCD/dCL = 2 * K * CL, we have:
Solving this gives the condition for maximum L/D:
Substituting this back into the drag polar, we find that at maximum L/D, the parasite drag equals the induced drag (CD,0 = K * CL2), resulting in a total drag coefficient of 2 * CD,0. The maximum lift-to-drag ratio is therefore:
Derive an equation for the total drag condition and drag reduction methods.
Answer
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Derive an expression for range and endurance for aircraft with thrust producing engines with the necessary equations.
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Describe the equations of motion of an aircraft undergoing lateral maneuver or level turn and derive an expression for radius of turn. Discuss with the help of a diagram the maneuver boundaries for turning performance.
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Derive the expression for the Maximum Climb Angle by using analytical approach for jet propelled airplane.
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Given an airplane mass of 50000 kg, Lift/Drag ratio 10, thrust per engine 60000 N, assume g = 10 m/s2. For a straight, steady, wings level climb of a twin engine airplane. Calculate the all engine climb gradient.
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Explain about the transport aircraft maneuver performance and military aircraft maneuver Performance.
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Determine the load factor, bank angle turn radius for an aircraft in a level turn at a true speed of 120km and a turn rate of 15 deg/s.
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Explain about the boost glide trajectory with graphical solution and iteration method with neat sketches.
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Explain the effect on the take-off distances of the flight variables.
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Find lift to drag ratio when drag coefficient at zero lift is 0.2 density of air at 10 km is 0.4135 kg/cubic meter and speed of aircraft is 300 kmph. The mass of the aircraft is 5000 kg area of wing plan form is 5 sqm and its AR is 6, span efficiency factor is 1.
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