Part-66 Module 8: Basic Aerodynamics

There are five topics under EASA and four under the UK CAA, and the running order is the argument: nothing after the first row can be answered without it, so the module opens on the air and not on the aeroplane. Physics of the atmosphere is the floor the rest stands on, and it’s largely one idea told several ways, since pressure falls as you climb, temperature falls with it up to a point, and humidity swaps heavier air for lighter, so every one of those roads ends at air density. A wing has no idea what altitude it’s at, and what it responds to, like the engine, is how much air is actually there. That’s why the same aeroplane wants more runway on a hot afternoon at a high airfield than on a cold morning at sea level.

Aerodynamics, topic 8.2, is what the air does around a body. The boundary layer clings to the skin and turns from laminar to turbulent along it, then separates when made to climb too steep a pressure gradient. Then the chord line, with the camber measured from it, the angle of attack between that chord line and the oncoming air, and two kinds of drag: the cost of pushing a shape through air, against the quite different drag that is the price of making lift. Theory of flight, 8.3, puts all of that on an aeroplane: the four forces in balance, what a turn does to the stalling speed once the wing carries more than its own weight, the edges of the flight envelope, and the flaps and slats that buy a low speed margin back by adding camber and waking up the flow over the wing.

Somewhere below Mach one, the air stops behaving like a conveniently incompressible fluid, and topic 8.4 is where the syllabus deals with what happens next. Sound travels at a speed set by temperature alone, so an aeroplane climbing into colder air closes on it without changing its indicated speed, and the flow over the thickest part of the wing goes supersonic well before the aeroplane does, stands a shock wave there, and separates behind it. The sweep of a wing and the row of vortex generators ahead of a control surface are answers to that, and they’re on the airframe you’ll be signing for.

Flight stability and dynamics closes the module, and it’s the part that bears hardest on the spanner work. Stability is whether an aeroplane disturbed in pitch, roll or yaw tends back towards where it started, and how it behaves on the way there: a tailplane sized to hold a nose that wants to drop, dihedral that turns a sideslip into a roll back towards level. EASA’s Module 11 has you rigging and mass balancing those surfaces to a level 3 standard, and this is the module that says what a surface left half a degree out actually does to the aeroplane.

Here EASA asks 24 questions in 30 minutes, against 20 in 25 from the UK CAA, and the gap between them is one row of the syllabus rather than any difference of standard, because EASA sets five topics in this module and the UK CAA sets four, the missing one being the high speed row. It hasn’t been dropped: the UK CAA examines high speed flight in Module 11A instead, where it appears as 11.1.2.

Passing at 75% takes 18 correct answers under EASA and forgives 6, while under the UK CAA it takes 15 and forgives 5. A UK candidate looking at the smaller of those allowances isn’t looking at a smaller subject, only at one filed elsewhere. Compressibility, shock waves and the behaviour of an aerofoil near the speed of sound are ground an EASA candidate risks part of this margin on, and ground a UK candidate risks part of quite another margin on, in a paper where plenty else is competing for the same room. Nothing about the shorter sitting makes the aeroplane any slower.

Every row EASA sets in Module 8 sits at level 2, so nothing in it is background reading and nothing in it reaches the depth level 3 asks for. What the paper wants instead is precision: angle of attack and pitch attitude aren’t the same thing, and neither are indicated airspeed and true airspeed, so a question can turn entirely on which one of the pair its stem happens to name.

There’s no UK entry at row 8.5, and that blank is a renumbering rather than a subject the UK CAA leaves out, and the section beneath the table says where the material has gone. Row 8.4 above it carries the UK CAA’s own wording underneath EASA’s, because at that number the two texts aren’t describing the same subject at all, and everywhere above those two rows the tables agree title for title. The EASA column is level 2 the whole way down, the UK column matches it on our reading of the assimilated text, and nothing on either side is marked as not required for B1.1.

Yes, and in two ways at once. The paper is the visible one: 24 questions in 30 minutes against 20 in 25, and the distance between those figures isn’t a difference of standard but the width of a single topic, since EASA carries five of them here and the UK CAA four. Of the four papers where the two authorities part ways on length, this is the one whose difference you can put a finger on in the table.

The missing row is “High speed airflow”, and the UK has no topic for it anywhere in Module 8, so UK 8.4 isn’t EASA’s 8.4 at all: it’s Flight stability and dynamics, which EASA numbers 8.5. Both texts word 8.1 to 8.3 identically, so the whole difference sits in those last two numbers, and it’s the kind a single table can only half show.

None of that means a UK candidate is examined on less: the material is in the UK syllabus, in Module 11A, as topic 11.1.2 High speed flight. So Mach number and the shock wave reach a UK candidate through the applied aeroplane paper rather than the basic one, while an EASA candidate meets the same ground earlier and in a more general form. What it changes in practice is your revision material rather than your knowledge, so work from a course built around EASA’s Module 8 for a UK paper and you’ll spend time on a row that isn’t on it. Work from a UK one for an EASA paper and you’ll walk into the exam never having been taught 8.4 at all.

The wider split between the two authorities is on the EASA versus UK CAA page: mutual recognition, which licence to go for, and what happened to the conversion route.

This page covers one of the 13 papers. The rest of the guide covers the route they sit inside: what the exam is, what else you must have done besides passing it, and how the two authorities differ.

Both authorities require the same thirteen subjects. Only the numbering and some of the titles differ, and the UK still uses the A suffix on four of them where EASA has dropped it. Each has a page of its own.