Q1. What is a vector?
ANSWER: A quantity that has both magnitude and direction. A resultant
vector may be divided into separate components.
Q2. What is air density?
ANSWER: The total mass of air particles per unit volume (mass/volume).
Denoted by rho (ρ).
Q3. What is a moment?
ANSWER: A rotational force acting around a fixed point. Calculated as Force
× Distance (moment arm).
Q4. What is a moment arm?
ANSWER: The perpendicular distance from the pivot point to the line of action
of the force.
Q5. What are the requirements for an aircraft to be in equilibrium flight?
ANSWER: The sum of all forces AND the sum of all moments around the
center of gravity must equal zero.
Q6. Can equilibrium flight be achieved in a turn?
ANSWER: No. A turn involves acceleration (centripetal), so there are
unbalanced moments and forces.
Q7. What are the requirements for trimmed flight?
ANSWER: The sum of all moments around the center of gravity must equal
zero. Forces need not be balanced.
Q8. What remains constant in trimmed flight?
ANSWER: Aircraft attitude (pitch, roll, yaw orientation) remains constant.
Q9. Can trimmed flight be achieved in a turn?
ANSWER: Yes. Moments can be balanced even when accelerating in a level
turn.
Page 1 of 20
,Q10. What is the relationship between temperature and altitude?
ANSWER: Air temperature decreases linearly with altitude at 2°C per 1,000
feet up to 36,000 feet. This is called the average lapse rate.
Q11. What is a streamline?
ANSWER: The path that air particles follow in steady (non-turbulent) airflow.
Q12. What is a streamtube and what kind of system is it?
ANSWER: A collection of many adjacent streamlines that form a tube. It is a
closed system — no air crosses the boundaries of the streamtube.
Q13. What is the relationship between humidity and air density?
ANSWER: Inverse relationship: as humidity increases, air density decreases
(moist air is less dense than dry air).
Q14. State the General Gas Law.
ANSWER: Pressure = Density × Temperature × Gas Constant (P = ρRT). It
relates the pressure, density, and temperature of a gas.
Q15. What is static pressure?
ANSWER: The weight of the air column above a given point; the pressure
exerted by air molecules not in motion relative to the surface.
Q16. What is dynamic pressure (q)?
ANSWER: The pressure resulting from the motion of air. q = ½ρV². It
increases with both air density and velocity.
Q17. State Bernoulli's Equation.
ANSWER: Total Pressure = Static Pressure + Dynamic Pressure (Pt = Ps +
q). Total pressure is constant in a streamtube.
Q18. What is the continuity equation?
ANSWER: ρ₁A₁V₁ = ρ₂A₂V₂. For incompressible flow, A₁V₁ = A₂V₂. As cross-
sectional area decreases, velocity increases.
Q19. What is the aerodynamic center (AC)?
ANSWER: The point on the airfoil where all aerodynamic forces act and
where the pitching moment coefficient remains constant with changes in AOA.
Located approximately 25% aft of the leading edge (quarter chord).
Q20. Where is the center of gravity (CG)?
ANSWER: The point at which all of an aircraft's weight is considered to be
concentrated. The aircraft balances around this point.
Page 2 of 20
, Q21. What is the center of pressure (CP)?
ANSWER: The point along the chord line where the resultant aerodynamic
force acts. It moves with changes in angle of attack.
Q22. Define relative wind.
ANSWER: The airflow that is opposite in direction to the aircraft's flight path. It
is determined by the direction the aircraft is moving.
Q23. Define angle of attack (AOA).
ANSWER: The angle formed between the chord line of the airfoil and the
relative wind. Denoted by alpha (α).
Q24. Define pitch attitude.
ANSWER: The angle between the aircraft's longitudinal axis and the horizon.
Q25. Define angle of incidence.
ANSWER: The fixed angle between the wing chord line and the aircraft's
longitudinal axis. It is built into the aircraft structure and does not change in
flight.
LESSON 2 — LIFT & DRAG (Q26–Q45)
Q26. Define lift.
ANSWER: The aerodynamic force that acts perpendicular to the relative wind.
It is generated by pressure distribution over the airfoil.
Q27. Define drag.
ANSWER: The aerodynamic force that acts parallel to the relative wind and
opposes motion. It is the component of the total aerodynamic force in the drag
direction.
Q28. What is the lift equation?
ANSWER: L = CL × q × S = CL × ½ρV² × S. Where CL = lift coefficient, ρ = air
density, V = velocity, S = wing area.
Q29. What factors affect lift?
ANSWER: Coefficient of lift (CL), air density (ρ), velocity (V²), and wing area
(S). CL is affected by AOA and airfoil shape.
Q30. What is the drag equation?
ANSWER: D = CD × q × S = CD × ½ρV² × S. Where CD = drag coefficient,
determined by AOA, shape, and surface roughness.
Q31. Define parasite drag and its two components.
Page 3 of 20
ANSWER: A quantity that has both magnitude and direction. A resultant
vector may be divided into separate components.
Q2. What is air density?
ANSWER: The total mass of air particles per unit volume (mass/volume).
Denoted by rho (ρ).
Q3. What is a moment?
ANSWER: A rotational force acting around a fixed point. Calculated as Force
× Distance (moment arm).
Q4. What is a moment arm?
ANSWER: The perpendicular distance from the pivot point to the line of action
of the force.
Q5. What are the requirements for an aircraft to be in equilibrium flight?
ANSWER: The sum of all forces AND the sum of all moments around the
center of gravity must equal zero.
Q6. Can equilibrium flight be achieved in a turn?
ANSWER: No. A turn involves acceleration (centripetal), so there are
unbalanced moments and forces.
Q7. What are the requirements for trimmed flight?
ANSWER: The sum of all moments around the center of gravity must equal
zero. Forces need not be balanced.
Q8. What remains constant in trimmed flight?
ANSWER: Aircraft attitude (pitch, roll, yaw orientation) remains constant.
Q9. Can trimmed flight be achieved in a turn?
ANSWER: Yes. Moments can be balanced even when accelerating in a level
turn.
Page 1 of 20
,Q10. What is the relationship between temperature and altitude?
ANSWER: Air temperature decreases linearly with altitude at 2°C per 1,000
feet up to 36,000 feet. This is called the average lapse rate.
Q11. What is a streamline?
ANSWER: The path that air particles follow in steady (non-turbulent) airflow.
Q12. What is a streamtube and what kind of system is it?
ANSWER: A collection of many adjacent streamlines that form a tube. It is a
closed system — no air crosses the boundaries of the streamtube.
Q13. What is the relationship between humidity and air density?
ANSWER: Inverse relationship: as humidity increases, air density decreases
(moist air is less dense than dry air).
Q14. State the General Gas Law.
ANSWER: Pressure = Density × Temperature × Gas Constant (P = ρRT). It
relates the pressure, density, and temperature of a gas.
Q15. What is static pressure?
ANSWER: The weight of the air column above a given point; the pressure
exerted by air molecules not in motion relative to the surface.
Q16. What is dynamic pressure (q)?
ANSWER: The pressure resulting from the motion of air. q = ½ρV². It
increases with both air density and velocity.
Q17. State Bernoulli's Equation.
ANSWER: Total Pressure = Static Pressure + Dynamic Pressure (Pt = Ps +
q). Total pressure is constant in a streamtube.
Q18. What is the continuity equation?
ANSWER: ρ₁A₁V₁ = ρ₂A₂V₂. For incompressible flow, A₁V₁ = A₂V₂. As cross-
sectional area decreases, velocity increases.
Q19. What is the aerodynamic center (AC)?
ANSWER: The point on the airfoil where all aerodynamic forces act and
where the pitching moment coefficient remains constant with changes in AOA.
Located approximately 25% aft of the leading edge (quarter chord).
Q20. Where is the center of gravity (CG)?
ANSWER: The point at which all of an aircraft's weight is considered to be
concentrated. The aircraft balances around this point.
Page 2 of 20
, Q21. What is the center of pressure (CP)?
ANSWER: The point along the chord line where the resultant aerodynamic
force acts. It moves with changes in angle of attack.
Q22. Define relative wind.
ANSWER: The airflow that is opposite in direction to the aircraft's flight path. It
is determined by the direction the aircraft is moving.
Q23. Define angle of attack (AOA).
ANSWER: The angle formed between the chord line of the airfoil and the
relative wind. Denoted by alpha (α).
Q24. Define pitch attitude.
ANSWER: The angle between the aircraft's longitudinal axis and the horizon.
Q25. Define angle of incidence.
ANSWER: The fixed angle between the wing chord line and the aircraft's
longitudinal axis. It is built into the aircraft structure and does not change in
flight.
LESSON 2 — LIFT & DRAG (Q26–Q45)
Q26. Define lift.
ANSWER: The aerodynamic force that acts perpendicular to the relative wind.
It is generated by pressure distribution over the airfoil.
Q27. Define drag.
ANSWER: The aerodynamic force that acts parallel to the relative wind and
opposes motion. It is the component of the total aerodynamic force in the drag
direction.
Q28. What is the lift equation?
ANSWER: L = CL × q × S = CL × ½ρV² × S. Where CL = lift coefficient, ρ = air
density, V = velocity, S = wing area.
Q29. What factors affect lift?
ANSWER: Coefficient of lift (CL), air density (ρ), velocity (V²), and wing area
(S). CL is affected by AOA and airfoil shape.
Q30. What is the drag equation?
ANSWER: D = CD × q × S = CD × ½ρV² × S. Where CD = drag coefficient,
determined by AOA, shape, and surface roughness.
Q31. Define parasite drag and its two components.
Page 3 of 20
