Principles of Flight
The full EASA ATPL(A) Principles of Flight syllabus, taught properly: subsonic and high-speed aerodynamics, stall, stability and control, limitations, propellers and flight mechanics — every learning objective explained with worked examples and the equations set out step by step.
How air behaves and how a wing turns that behaviour into lift: the definitions, laws and flow mechanics every later topic of Principles of Flight builds on.
Everything in Principles of Flight rests on this module. It starts from the vocabulary, the quantities, units and laws that aerodynamic arguments are written in, and builds up through airflow around aerofoils to lift, drag and the devices that change them. Work through it in order: later modules assume this one without warning.
What changes when an aeroplane flies fast enough for the air's compressibility to matter: the speed of sound, Mach number, shock waves, and the design tricks that let airliners cruise at the edge of them.
The subsonic module treated air as incompressible, a safe fiction at low speed that fails as flight speed approaches the speed of sound. This module follows what actually happens: how the speed of sound sets the scale, how shock waves form and what they do to lift, drag and pitch, and how swept wings and supercritical sections push the trouble to higher Mach numbers. Jet transport aircraft cruise inside this module every day of their working lives.
What actually happens when a wing stops flying: the separation mechanics, the speeds and load factors, the warning systems, the special cases from power-on stalls to deep stall and spin, and the buffet boundaries that fence in high-altitude flight.
Every lesson so far has treated the stall as a boundary: the place where the lift curve ends. This module goes inside it: how separation actually develops, what decides the speed at which it arrives, how the aeroplane warns its pilot, what changes when power, sweep, ice or a spin get involved, and how the same physics reappears at high altitude as the buffet boundary. It is the safety heart of the subject, and the exam treats it accordingly.
Why an aeroplane holds its flight condition when the pilot lets go: the balance of forces and moments, the stabilising surfaces and CG limits that keep pitch, yaw and roll in hand, and the oscillations that appear when the balances interact.
An aeroplane spends most of its life not being actively flown: trimmed out, hands light on the controls, riding gusts it must absorb on its own. This module explains why a well-designed aeroplane does that: starting from the bare definitions of stability, through the longitudinal, directional and lateral balances and the CG limits they impose, to the coupled oscillations (Dutch roll, the spiral, the phugoid) that emerge when those balances interact. The stall module borrowed its ideas repeatedly; here they are built properly.
How the pilot commands the aeroplane: the surfaces that generate pitch, roll and yaw, the interactions between them, the tricks that keep control forces humane, fly-by-wire, and the trim systems that make an aircraft flyable for hours.
The stability module studied the moments an aeroplane generates by itself; this module studies the moments the pilot orders. The physics is deliberately the same (every control surface is an aerofoil whose lift is being adjusted), but the questions change: how much force must the pilot apply, how does one control's action spill into another axis, and what stands between a human hand and a surface fighting a four-hundred-knot airstream.
Where the flight envelope's edges come from: flutter and the aeroelastic limits, the placarded speeds from flap limits to VNE and MMO, the V-n manoeuvring envelope with its load-factor corners, and the gust loads that draw their own boundary.
Every speed and load-factor limit in the manual is a boundary someone computed, tested and certified. This module traces the limits to their sources: the aeroelastic phenomena that forbid certain speeds outright, the placarded speeds that protect structure and systems, and the two envelopes (manoeuvring and gust) that together define where the aircraft may be flown and what may be demanded of it there.
The rotating wing that turns engine torque into thrust: the blade element and its velocity triangle, pitch and constant-speed operation, efficiency, windmilling and feathering, and the asymmetric and secondary effects every propeller pilot must anticipate.
A propeller blade is a wing flown in a spiral. Everything this course taught about aerofoils applies to it, with one complication: each blade station meets the air at its own speed and angle, and the pilot (or a governor) can change the blade's pitch in flight. This module builds the blade element, follows it through normal, windmilling, feathered and reverse operation, and closes with the moments a turning propeller quietly imposes on the whole aircraft.
The whole course applied to whole flights: the four forces balanced in level flight, climb, descent, glide and turn, the calculations the exam loves for each, and the asymmetric-thrust case that certification, checkrides and this subject's hardest questions all share.
Every module so far studied a force or a moment; this closing module studies flights. The method never changes: draw the forces on the aircraft, resolve them along and across the flight path, and demand that they balance. From that single recipe come the climb-angle formula, the glide range, the turn radius and load factor, and the minimum control speeds of asymmetric flight — the exam's most reliable calculation questions, all of them.