JNTU
JNTU B.Tech III AIRCRAFT PERFORMANCE AND STABILITY Previous Question Paper (February - 2022 - R18)
Answer any five questions. All questions carry equal marks.
Main
What is total air plane drag?
Answer
Total airplane drag is the aerodynamic force that opposes the motion of an aircraft through the air. It is the sum of two primary components: parasite drag and induced drag.
Parasite drag results from the aircraft's movement through the air and includes skin friction drag (due to air viscosity), form drag (due to the shape of the aircraft), and interference drag (due to the interaction of airflow between different components). It is proportional to the square of the velocity.
Induced drag is a byproduct of lift generation. As wings produce lift, they create wingtip vortices, which alter the local airflow and tilt the lift vector rearward, creating a drag component. Induced drag is inversely proportional to the square of the velocity.
The total drag equation is expressed as:
where CD,0 is the parasite drag coefficient and CD,i is the induced drag coefficient.
The atmosphere of certain planet is made of gases whose average specific gas constant is 4257 J/kg.K. The acceleration due to gravity is 25.6 m/s2. If the atmosphere is only Isothermal layer with a typical temperature of 170 oK, Calculate the altitude above the surface where the pressure is one-fourth that of earth surface.
Answer
For an isothermal atmosphere, the pressure variation with altitude is given by the hydrostatic equation integrated with the ideal gas law:
Given the condition that the pressure at altitude h is one-fourth of the surface pressure (P/P0 = 0.25), we have:
Taking the natural logarithm on both sides:
Solving for h:
The altitude above the surface is approximately 39.18 km.
Calculate properties of atmosphere at following altitudes using equations:
i) 64.2km altitude
ii) 29.6km altitude.
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Derive an expression for minimum drag speed.
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An aeroplane having a weight of 118 kN is fitted with non-rectangular wing having an area 53 m2 and aspect ratio 8.2. The power plant of airplane provides static thrust of 99 kN at sea level. It is jet engine. Calculate power required and maximum velocity at 4.95 km altitude. Assume that engine thrust varies directly with free stream.
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What is the effect of weight and altitude on climb performance?
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Illustrate Head wind, tail wind, and cross wind and their impact on flight performance of aircraft.
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Draw the power required and power available curve for a jet engine and piston engine aircraft and state your observations.
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An aircraft flying with 300 H.P at a speed of 290 km/hr. It has used fuel up to 19% of the total weight. What is the new level flight and corresponding Horse Power?
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Obtain an expression for turn radius and turn rate for maneuvering flight.
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What do you mean by fuel planning? Explain the basic principles of reserve tankering.
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