The Aerofoil and Subsonic AirflowAircraft & Engines — DGCA CPL practice questions
Question 1 of 5
The angle of incidence is the fixed angle between:
All 5 questions — The Aerofoil and Subsonic Airflow
Aircraft & Engines · DGCA CPL. The correct option is marked on each.
Q1. The angle of incidence is the fixed angle between:
- A.Chord line and relative airflow
- B.Chord line and the aircraft's longitudinal axis✓
- C.Mean camber line and chord line
- D.Relative airflow and flight path
Why: Incidence is built in by the designer: chord line vs longitudinal axis. Chord line vs relative airflow is the angle of ATTACK.
Q2. A symmetrical aerofoil is one in which:
- A.The thickness/chord ratio is zero
- B.The mean camber line and chord line coincide✓
- C.The leading edge radius is zero
- D.Maximum camber is at 50% chord
Why: No camber means the mean camber line lies on the chord line — upper and lower surfaces are mirror images.
Q3. Lift is defined as the component of the Total Reaction acting:
- A.Parallel to the chord line
- B.Perpendicular to the relative airflow✓
- C.Parallel to the relative airflow
- D.Perpendicular to the longitudinal axis
Why: Lift acts perpendicular to the relative airflow; the parallel component of the total reaction is drag.
Q4. The Centre of Pressure is the point:
- A.Where the aircraft's weight acts
- B.On the chord line through which total lift is considered to act✓
- C.Where the relative airflow is fastest
- D.At 50% of the chord
Why: The CP is the point on the chord line through which the total lift force effectively acts; its position moves with angle of attack.
Q5. The Relative Air Flow (RAF) is:
- A.Parallel and opposite to the aircraft's flight path✓
- B.Always horizontal
- C.Parallel to the chord line
- D.Perpendicular to the flight path
Why: RAF is parallel and opposite to the flight path, with magnitude equal to TAS.