Standard Book, Technical General
The Atmosphere: DGCA Technical General questions
Most aerodynamic sums start from air pressure, temperature and density. Those values come from the ICAO Standard Atmosphere, a reference model with a sea level pressure of 1013.25 hPa, a sea level temperature of 15 degrees C and a steady lapse rate through the troposphere.
Its 21 questions are mostly multiple statement items on ISA, density, dynamic pressure and the steps from IAS to TAS. DGCA exam sessions have included 1 of these ISA questions.
The ISA lapse rate holds to 11 km, about 36,000 ft, not 11,000 ft. The speed of sound depends on temperature alone. CAS is IAS corrected for instrument and position error, EAS then removes compressibility error, and a density correction gives TAS.
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Question 1 of 5
Mach number is:
Question 2 of 5
When considering air, which combination of statements is true? 1 Air has mass. 2 Air is not compressible. 3 Air is able to flow or change its shape under even small pressures. 4 The viscosity of air is very high. 5 Moving air has kinetic energy.
Question 3 of 5
When considering static pressure, which statements are correct? 1 In aviation, static pressure can be measured in hectopascals. 2 The SI unit for static pressure is N/m2. 3 Static pressure is the product of the mass of air pressing down on the air beneath. 4 Called static pressure because of the air's stationary or static presence. 5 The lower the altitude, the greater the static pressure.
Question 4 of 5
When considering the ICAO ISA, which statements are correct? 1 Temperature lapse rate is 2°C per 1000 ft up to 11,000 ft. 2 Sea level temperature is assumed to be 15°C. 3 Sea level static pressure is assumed to be 1.225 kg/m3. 4 Sea level density is assumed to be 1013.25 hPa.
Question 5 of 5
Air density is:
16 more questions in this chapter
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