Stalling Mass Brief Aim • To discover the aerodynamic principles and factors of a stall. Considering the approach to a stall, recognition of the symptoms, and how to recover with minimum height loss in varying configurations. Application – High AoA / Low IAS Operations – Take-off and landing – Inadvertent stall recovery Overview • Aim • Revision • Definitions • Principles – Stalling • Considerations • Air Exercise • Airmanship • Review Revision • Aerofoil and Lift Airspeed Lift Revision Drag Induced Drag Parasite drag TOTAL DRAG Slow Fast DRAG AIRSPEED Minimum Drag Best L/D Ratio Revision • Lift distribution Pressure distribution Centre of pressure Aerodynamic Force + _ ≡ Definitions • Critical angle AoA CL 16º Definitions • Stall – Occurs when the AoA exceeds the critical angle • Stall speed (VS) – In following configuration: MTOW @ MSL, Idle power, straight and level altitude, most forward CG position, clean configuration. Definitions • Streamline/Laminar Airflow • Turbulent Airflow • Separation Point • Boundary Layer • Transition Region • Stagnation Point Definitions • Load Factor Weight Load Factor Lift cosAngle of Bank Load Factor 1 Principles CL CL CL CL L L L L W W W W 110kt 4o 70kt 8o 44kt 16o <44kt >16o IAS AoA
Principles Usual Symptoms Close to stall 1. High nose attitude 2. Low IAS 3. Reduced effectiveness of controls 4. Stall Warning 5. Control Buffet Symptom after stall 1. Nose pitch down 2. Loss of height
Considerations • Manoeuvres Actual Stalled Flightpath Attempted 3G Pullout Planned Flightpath Considerations • Manoeuvres V V LF New StallSpeed S CosAoB LF 1 Increased Stall Speed 1G 2G 3G 4G 2.0 1.8 1.6 1.4 1.2 1.0 “g” load A stall occurs at an AoA, not an IAS Considerations • Weight L L W W 16o 16o 40 kt 44 kt Considerations • Centre of Gravity Weight Lift Considerations • Ice Considerations • Flap Relative Airflow Stall with flap Lower Nose Attitude Stall without flap High Nose Attitude Considerations • Power Thrust TH TV Considerations • Stability in the stall
Air Exercise • Pre-Stalling Checks – Height sufficient to recover by 3000ft – Hatches/Harnesses secure – Engine Temperature & Pressures – Location – not above a populated area – Loose articles secure – Lookout (360 degree turn) Air Exercise • Entry – Pick a reference point ( maintain with rudder) – Retard throttle, maintaining height – Note the symptoms • Stall • Recovery – Lower nose to horizon – Allow speed to increase through 65KIAS, full power – Climb out • Wing drop recovery – Apply opposite rudder to stop yaw and or bank – Lower nose to unstall – Passing 65KIAS, full power – Climb out Airmanship • Inadvertent stalls should never occur • Lookout • Smooth co-ordinated control input • Correct handover/takeover procedure • Monitor engine gauges Review • Critical angle • Separation point • Boundary layer • Load factor • Manoeuvres • Weight • CoG • Ice • Flap • Power |