Principles of Flight
Principles of flight questions test physical reasoning. Start with the four forces and the generation of lift: the pressure distribution over the wing, angle of attack, and the lift equation where lift is proportional to density, velocity squared, and wing area. Understand the stall as exceeding the critical angle of attack, and why stall speed varies with mass, load factor, and altitude.
Learn the drag types: parasite drag rising with velocity squared, and induced drag falling as velocity increases. The total drag curve and the speed for minimum drag and maximum endurance are key relationships. Understand stability: static and dynamic, longitudinal, lateral, and directional, and the role of the tailplane, dihedral, and fin.
Know the effects of flaps, slats, and spoilers, and the meaning of the load factor and the manoeuvring speed. Understand how a turn increases load factor and stall speed.
Worked example
In a 60° banked level turn, load factor is 1/cos 60° = 2. Stall speed increases by the square root of the load factor, so it rises by about 41%. Use the square-root rule for any load factor question.
Traps include confusing angle of attack with pitch attitude, mixing parasite and induced drag trends, and forgetting the load factor effect in turns.