Aeronautics - General Knowledge: Flight Principles and Performance
Forces and control
General-knowledge questions link aerodynamics to practical handling: lift depends on angle of attack, airspeed, wing area and air density; induced drag decreases as speed increases, while parasite drag rises with the square of speed. Know the four forces in climb, glide and turn, why an aft centre of gravity reduces longitudinal stability, and how flaps change lift, drag and stall speed. Stability questions distinguish static from dynamic stability and longitudinal, lateral and directional axes. Performance questions combine weight, density altitude, wind and runway slope; systems questions cover carburettor icing, mixture, electrical load and pre-flight inspection.
Traps
Stall questions often imply that a stall is caused by low speed alone; the real trigger is exceeding the critical angle of attack, which can occur at any speed or attitude. Load factor questions trap candidates who forget that stall speed increases with the square root of load factor. In a level 60° bank, load factor is 2, so stall speed rises by about 41%. Weight-and-balance traps include confusing empty weight with basic empty weight and forgetting that fuel and passengers shift the CG. Carburettor icing is most likely in humid air at moderate temperatures, not only in freezing weather.
Worked example
An aircraft stalls at 50 KCAS in level flight. In a 60° level bank, load factor = 1/cos 60° = 2. New stall speed = 50 × √2 ≈ 71 KCAS. Rule of thumb: stall speed rises by about 41% at 60° bank, so keep extra speed and avoid abrupt control input near the ground.