Aerodynamics
Lift, weight, thrust, and drag explain stalls, steep turns, and ground effect.
Four forces
In steady unaccelerated flight, lift equals weight and thrust equals drag. Parasite drag rises with speed; induced drag falls with speed. Total drag is minimum near L/D max, which is related to best glide speed.
Angle of attack & stalls
AOA is the angle between the chord line and relative wind. The wing stalls at the critical AOA regardless of airspeed. Weight, load factor, and CG change stall airspeed, not the critical AOA concept.
Safety
Uncoordinated stalls set up spins. Recovery starts by reducing AOA. Fly your POH/AFH procedure.
Turns & load factor
In a level turn, lift must increase. Load factor n = 1/cos(bank). At 60° bank, n ≈ 2. Stall speed rises with the square root of load factor.
Ground effect
Within about one wingspan of the surface, induced drag decreases. That can cause float on landing or a premature liftoff that will not climb out of ground effect on a heavy/soft/short-field takeoff.
Practice questions
1. Does a wing always stall at the same airspeed?
Show Answer
No. It stalls at critical AOA; stall speed varies with weight, G, CG, etc.
2. Load factor in a level 60° bank?
Show Answer
About 2 Gs.
3. Primary aerodynamic effect of ground effect?
Show Answer
Reduced induced drag near the surface.