Basic Aerodynamics and Flight Mechanics
What you must understand
Begin with the four forces and their balance in steady flight. Understand how lift is generated - circulation and pressure distribution, not just Bernoulli - and the meaning of angle of attack, the critical angle, and the stall. Know the lift formula qualitatively: lift rises with density, speed squared, and wing area, and with lift coefficient up to the stall. Understand induced drag and its relationship to speed (high at low speed), parasite drag (high at high speed), and the total drag curve and the speed for minimum drag.
Know stability: static and dynamic, longitudinal, lateral and directional, and the role of the tailplane, fin and dihedral. Understand the effect of centre of gravity position on stability and control, and why forward CG increases stability but reduces performance. Understand load factor, the manoeuvring envelope, and why load factor increases in a level turn. Know the effects of altitude on true airspeed and stall speed, and the meaning of Mach number and critical Mach.
Traps
A classic trap is assuming stall speed is fixed. It rises with weight and load factor and with altitude in terms of true airspeed. Another is confusing best glide speed (minimum drag) with minimum sink speed.
Worked example
In a level turn at 60° bank, load factor n = 1/cos(60°) = 2. Stall speed increases with the square root of load factor, so the stall speed rises by √2 ≈ 1.41 times the straight-and-level value.