PoF 19/08/25

Explain stall recognition cues (stall-warning + buffet, lack of authority, uncommanded pitch/roll).

Stall recognition includes continuous stall-warning activation, aerodynamic buffet, reduced pitch or roll control authority, uncommanded nose-down pitch or roll, and inability to arrest descent—regardless of airspeed or attitude.

Explain why Cn depends on sideslip angle beta, equilibrium beta = 0, and conditions.

The yawing moment coefficient (Cn) changes with sideslip angle (beta); a positive slope (dCn/dBeta > 0) indicates directional stability. Equilibrium beta = 0 when there's no asymmetric thrust or imbalance, meaning no net yawing moment.

Explain situations where turn radius is critical (departure, arrival plates, approach speed limits).

Turn radius is critical during SID/STAR procedures, missed approaches, and when maneuvering in confined airspace. Exceeding speed limits can lead to overshooting protected airspace or violating ATC clearances.

Describe & explain influence of CG, thrust, slipstream, mass, sweep, contamination, altitude on stall speed.

Forward CG increases stall speed due to increased tail downforce required. High thrust and slipstream can lower stall speed by energizing airflow. Higher mass, wing sweep, contamination (ice/dirt), and altitude increase stall speed due to degraded lift or compressibility effects.

Explain working principle of rudder, relation of deflection to normal-axis moment, and effect of sideslip.

The rudder controls yaw by deflecting airflow, creating a side force on the tail, which generates a moment about the normal (vertical) axis. Sideslip increases yaw moment, requiring rudder correction to maintain coordination.

Explain buffet/stall at high altitude (ITCZ, jet streams, CAT) and mitigation.

High-altitude flight near the ITCZ, jet streams, or clear-air turbulence (CAT) can cause sudden alpha increases, risking stall or buffet. Mitigation includes reducing Mach, increasing margin from stall buffet boundary, and avoiding turbulence regions.

Explain flap-setting errors (late/early selection) and their effects on distance, performance, buffet margins.

Late flap extension delays lift and increases landing distance; early extension increases drag and may cause premature stall. Incorrect flap settings reduce climb/descent performance and narrow buffet/stall margins.

Describe how wing, fin, fuselage, strakes contribute to static directional stability.

The vertical fin is the main contributor to yaw stability. Swept wings, dorsal/ventral fins, and fuselage shape at high alpha also help. Strakes and chines guide airflow to improve yaw damping and stability.

Explain buffet/stall at low altitude (thunderstorms, shear, turbulence, icing) and mitigation.

Turbulence, wind shear, or icing at low altitude can cause abrupt alpha changes, leading to buffet or stall. Mitigation includes using proper configuration, avoiding known hazards, and maintaining higher margins from stall.

Explain significant points of CL–alpha curve (zero lift, alpha=0, CLmax).

On the CL–alpha graph: zero lift is where CL = 0 (slightly negative alpha for cambered aerofoils), alpha = 0 is the reference point, and CLmax is the peak lift before stall (critical angle of attack, alphaCRIT).