1 QUIZ Intro/Air/basics aerodynamic theory

Which of the following statements, about a venturi in a subsonic airflow are correct? 1. The dynamic pressures in the undisturbed flow and in the throat are equal. 2. The total pressures in the undisturbed flow and in the throat are equal.

• 1 is incorrect and 2 is correct.
• 1 is correct and 2 is incorrect.
• 1 and 2 are incorrect.
• 1 and 2 are correct.

Assuming subsonic incompressible flow, how will air density change as air flows through a tube of increasing cross-sectional area? The air density:

• increases with increasing cross-sectional area.
• decreases with increasing cross-sectional area.
• does not vary.
• depends upon the shape of the tube alone and not its cross-sectional area

Considering subsonic incompressible airflow through a Venturi, which statement is correct? I. The static pressure in the undisturbed airflow is higher than in the throat. II. The speed in the undisturbed airflow is higher than in the throat.

• I is correct, II is correct.
• I is incorrect, II is correct.
• I is incorrect, II is incorrect.
• I is correct, II is incorrect.

True airspeed (TAS) is:

• Lower than the indicated airspeed (IAS) at altitudes below sea level, under ISA conditions.
• EAS corrected for compressibility.
• Higher than the indicated airspeed (IAS) at altitudes below sea level, under ISA conditions.
• Equal to the IAS, multiplied by the air density at sea level.

Given: pstat = static pressure; q = dynamic pressure; ptot = total pressure. In a convergent tube with an incompressible subsonic airflow, what pressure changes will occur?

• Pstat increases, q decreases, ptot remains constant.
• Pstat decreases, q increases, ptot increases.
• Pstat decreases, q increases, ptot decreases.
• Pstat decreases, q increases, ptot remains constant.

Which of these statements about weight or mass is correct?

• In the SI system the unit of measurement for weight is the kilogram.
• Mass = weight * volume.
• The mass of an object is independent of the acceleration due to gravity.
• The weight of an object is independent of the acceleration due to gravity.

The angle between the direction of the undisturbed airflow (relative wind) and the chord line of an aerofoil is the:

• climb path angle.
• same as the angle between chord line and fuselage axis.
• glide path angle.
• angle of attack.

An aeroplane’s angle of incidence is defined as the angle between the…

• fin chord line and the horizontal plane.
• lateral axis and the wing tip chord line.
• horizontal stabiliser chord line and the normal axis.
• longitudinal axis and the wing root chord line.

For a subsonic flow, the continuity equation states that if the cross-sectional area of a stream tube increases, the speed of the flow…

• first increases then decreases.
• does not change.
• decreases.
• increases.

The SI units of air density (I) and force (II) are:

• (I) kg / m², (II) kg.
• (I) N / kg, (II) kg.
• (I) kg / m³, (II) N.
• (I) N / m³, (II) N.