Exam code: CADA / CADHPass mark: 70% · 1.5 hrsFixed & Rotary specific streams
Aerodynamics is one of the 7 CASA CPL/PPL theory subjects under CASR Part 61 MOS Schedule 3.
Every topic below is drawn from the same syllabus registry that drives Aero Academic's Knowledge
Deficiency Report — including which regulatory citations are confirmed against the published MOS
text and which are still awaiting review.
Topics covered in depth
Angle of Attack & the Lift Curve
How CL, drag and the lift/drag ratio change as angle of attack increases to the stalling angle and beyond — read off the CL, CD and CL/CD graphs. The shared aerodynamic basis for an aeroplane wing and a helicopter rotor blade.
CASR Part 61 MOS Schedule 3 (AD) 2.1.1 (p.397) — Effect of changing angle of attack up to the stalling angleVerified“Explain the effect of changes in angle of attack up to the stalling angle on the following: (a) pressure changes above and below an aerofoil; (b) changes in airflow characteristics streamlined to turbulent; (c) lift and drag; (d) the boundary layer.”
CASR Part 61 MOS Schedule 3 (AD) 2.1.2 (p.397) — Identifying angles of attack on the CL, CD and CL/CD graphsVerified“With reference to CL, CD, CL/CD graphs identify angles of attack associated with the following: (a) minimum drag – maximum level flight speed; (b) maximum lift – stalling angle; (c) best CL/CD – best glide range and still air range.”
Common exam mistakes
The stall is defined by angle of attack, not by airspeed — a wing can stall at any speed or attitude.
Past the stalling angle, more angle of attack gives LESS lift, not more.
Best glide range and minimum drag occur at the SAME angle of attack — the best CL/CD point.
Recovery from a stall is to reduce angle of attack first; power and attitude do not un-stall a wing.
On a helicopter the retreating blade meets the lowest relative airflow and reaches this stalling angle first.
How Bernoulli's theorem of constant energy flow — kinetic energy (dynamic pressure) trading against potential energy (static pressure) — explains accelerating flow through a venturi and the pressure difference an aerofoil generates as air speeds up over the upper surface.
CASR Part 61 MOS Schedule 3 (AD) 2.2.1 (p.396) — Bernoulli's theorem — energy exchange through a venturi and over an aerofoilVerified“Apply Bernoulli's theorem of constant energy flow to describe how an aerofoil produces lift, limited to the variation of kinetic energy (dynamic pressure) and potential energy (static pressure) as air flows through a venturi or over a aerofoil.”
Common exam mistakes
Total energy (dynamic + static pressure) stays constant along a streamline — it is exchanged, not created.
Faster airflow over the upper cambered surface means LOWER static pressure there, not higher.
A venturi speeds up the flow through its narrowest section by the same energy trade, before the air ever meets a wing.
Bernoulli explains the pressure difference; it is not the complete picture of lift on its own — reaction/downwash also contributes.
Vortex Ring State & Loss of Tail Rotor Effectiveness
Two helicopter-specific descending-flight hazards: vortex ring state (settling with power), where the main rotor re-ingests its own tip-vortex downwash in a steep low-speed descent, and loss of tail rotor effectiveness, where relative wind direction starves the tail rotor of authority — the conditions that lead into each and the recovery action.
CASR Part 61 MOS Schedule 3 (AD) 2.2.3 (p.400) — Vortex ring state and loss of tail rotor effectiveness — conditions and recoveryVerified“Explain the meaning the following, including the conditions leading thereto and appropriate recovery action: (a) vortex ring state (settling with power); (b) loss of tail rotor effectiveness (LTE).”
Common exam mistakes
Vortex ring state needs power applied AND a steep, low-airspeed descent together — power alone or descent alone does not cause it.
Recovery from vortex ring state is to fly out of the disturbed downwash — forward cyclic to gain airspeed, not simply pulling more power, which can worsen the sink rate.
LTE is a loss of tail rotor authority relative to the wind, not a mechanical tail rotor failure — the tail rotor is still working.
LTE is most likely at low airspeed with a left/right crosswind or tailwind component (main-rotor-direction dependent), not necessarily at high power.
Vortex ring state affects the main rotor system; LTE affects the tail rotor — the recognition cues and recovery actions are different for each.
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