Uncontrolled copy not subject to amendment

1. Uncontrolled copy not subject to amendment Principles of Flight

2. Principles of Flight Learning Outcome 3: Know the principles of stalling

3. Principles of Flight Revision

4. Questions • What effect does a Trailing Edge Flap have on the Stalling • Speed? • Higher. • Lower. • c. The same. • d. No difference.

5. Questions • One type of Leading Edge Flap is: • Plain. • Slot. • c. Split. • d. Krueger.

6. Questions • What are some of the High Lift Devices on the Leading • Edge called? • a. Plain Flaps. • b. Ailerons. • c. Slats. • d. Split Flaps.

7. Stalling • Objectives: • Describe the Stall in terms of Lift. • State the generally used Critical or Stall • Angle of Attack. • Understand the relationship between Stalling and • Airspeed. • State where the Pilot obtains information regarding the • Aircraft’s Stalling Speed. • 5. List the Factors which affect the Stalling Speed.

8. Stalling It isESSENTIALthat a Pilot understands Stalling. During Take-Off and Landing, the Aircraft is at Low Speed. In Aerobatics the Aircraft experiences High “G”. What has Stalling got to do with these?

9. Lift = CLMAX½ρV2MINS Stalling Remember the Lift Formula? Lift = CL½ ρV2S If we slow down (reduce V) we must keep Lift the same (for Straight & Level Flight) by increasing CL. The Limit is CLMAX, so theEquivalent speed is VMIN (stalling speed) Cl Max α Crit AOA ~ 15o

10. Stalling Speed Is: The speed at which a clean aircraft (flaps up), At a stated weight, With the throttle closed, Flying straight and level, Can no longer maintain height.

11. The Mechanism of Stalling

12. TOWARDS HIGHER PRESSURE PLUS VISCOUS ADHESION - “ SLOWER” TOWARDS LOWER PRESSURE - FASTER TRANSITION POINT (PERHAPS) FROM LAMINAR TO TURBULENT BOUNDARY LAYER BOUNDARY LAYER SEPARATION – Low AoA

13. TOWARDS HIGHER PRESSURE PLUS VISCOUS ADHESION - “MUCHSLOWER” TOWARDS LOWER PRESSURE - FASTER SEPARATION POINT BOUNDARY LAYER SEPARATION – Higher AoA

14. TOWARDS LOWER PRESSURE - FASTER BOUNDARY LAYER SEPARATION – Wing Stalled SEPARATION COMPLETE

16. Factors affecting stalling speed Aircraft Weight

17. EFFECT OF WEIGHT Lift HEAVY WT = CL MAX½ ρV2 HEAVY STALL S  Lift BASIC WT = CL MAX½ρV2 BASIC STALL S

18. Lift HEAVY WT CL MAX½ ρV2 HEAVY STALL S Lift BASIC WT CL MAX½ρV2 BASIC STALL S EFFECT OF WEIGHT =

19. Lift HEAVY WT V2 HEAVY STALL = Lift BASIC WT V2 BASIC STALL LIFT HEAVY WT V2BASIC STALL = V2HEAVY STALL X LIFT BASIC WT LIFT HEAVY WT V2HEAVY STALL = V2BASIC STALL X LIFT BASIC WT EFFECT OF WEIGHT

20. LIFT HEAVY WT V2HEAVY STALL = V2BASIC STALL X LIFT BASIC WT LIFT HEAVY V STALL HVY = V STALL BASIC X LIFT BASIC Weight HEAVY V STALL HVY = V STALL BASIC X Weight BASIC EFFECT OF WEIGHT

21. Factors affecting stalling speed Pulling ‘g’

22. LIFT HEAVY LIFT BASIC SAME FOR PULLING “g” V STALL MAN’VRE = VSTALL BASIC X “g” V STALL MAN’VRE = 90 x 4 = 90 x 2 EFFECT OF ‘G’ V STALL HVY = V STALL BASIC X e.g. Vstall basic =90kts, 4g loop = 180kts

23. Danger Danger Danger Danger EFFECT OF ‘G’ If you pull ‘g’, the stalling speed increases, e.g. if you pull 4g the stalling speed doubles!

24. Factors affecting stalling speed Engine Thrust

25. Flight Path EFFECT OF THRUST ON STALLING Lift Thrust Weight

26. Flight Path EFFECT OF THRUST ON STALLING Lift Lift TR Thrust Weight

27. FLIGHT PATH EFFECT OF THRUST ON STALLING Aircraft in level flight have a high nose attitude at the stall, particularly swept wing aircraft. If the engine is at high power - two thrust components: 1. Along flight path (countering drag). 2. Vertical (opposing weight). Therefore less lift required from wings, so: SLOWER STALLING SPEED (V) AT CLMAX

28. NATURAL STALL WARNING Speed Nose Attitude Controls Light Buffet Heavy Buffet Nose Drop Wing Drop Descent

29. NATURAL STALL WARNING TURBULENT AIR MISSING TAILPLANE NORMAL FLIGHT

30. NATURAL STALL WARNING TURBULENT AIR MISSING TAILPLANE TURBULENT AIR JUST TOUCHING TAILPLANE STALL WARNING LIGHT BUFFET NORMAL FLIGHT

31. Aircraft Descending NATURAL STALL WARNING TURBULENT AIR JUST TOUCHING TAILPLANE TURBULENT AIR COVERING TAILPLANE STALL WARNING LIGHT BUFFET STALL HEAVY BUFFET

32. Synthetic Stall Warning Firefly/Tutor: Warning Horn Warning Light (Firefly only) Tucano: Warning Horn AoA Gauge Stick Shaker Indexer

33. Typical – Stall Warning Vane Vane held down by airflow Micro-switch not made No stall warning given Vane lifted up by airflow Micro-switch made Stall warning given

34. Example of a Stall Warning Vane

35. EFFECT OF FLAP Basic ‘Clean’ Situation Chord α Relative Airflow

36. EFFECT OF FLAP Flap Lowered Basic ‘Clean’ Situation Chord α Relative Airflow Effective Increase in AoA

37. EFFECT OF FLAP Flap Lowered Maintaining the Same Lift α To obtain the same CL the Attitude is Lowered to Reduce the AoA Effective Increase in AoA

38. EFFECT OF FLAP Cl Max Without Flap CL Critical Angle AoA AT STALL: WEIGHT = LIFT = CLMAX½ρ V2STALL S

39. EFFECT OF FLAP THIS IS IF THIS IS CONSTANT LESS MORE Cl Max More With Flap Cl Max Without Flap CL Nose lower at Stall Critical Angle AoA AT STALL: WEIGHT = LIFT = CLMAX½ρ V2STALL S

40. Stall Recovery

41. STANDARD STALL RECOVERY Move stick Centrally forward until buffet stops. Open throttle at the same time. Only then level the wings. Raise nose at a safe speed and climb.

42. Other Factors Affecting Stalling Ice: Alters the ‘Shape’ of the wing, this will reduce Lift. Damage: Can also reduce Lift ie after a ‘Birdstrike’.

43. Summary of Stalling Speeds What happens to the Stalling Speed if: Aircraft Weight Increases: Increase. If we Lower Flap: Decrease. If we are “Pulling G”: Increase. If the Aircraft is damaged or had a Birdstrike, it will probably: Increase. Using Engine Thrust: Decrease.

44. Stalling REMEMBER: An Aircraft can STALL in any Attitude, level, turning, upside-down etc. Where would we find our Stalling Speeds? Pilot’s Notes/Aircrew Manual etc.

45. Any Questions?

46. Stalling • Objectives: • Describe the Stall in terms of Lift. • State the generally used Critical or Stall • Angle of Attack. • Understand the relationship between Stalling and • Airspeed. • State where the Pilot obtains information regarding the • Aircraft’s Stalling Speed. • 5. List the Factors which affect the Stalling Speed.

47. Questions • What happens to Lift when a Wing is Stalled? • Lift Increases as Angle of Attack Decreases. • Lift Decreases as Angle of Attack Increases. • Lift is Greatly Reduced. • Lift Remains unchanged.

48. Questions • The Critical Angle of Attack is Generally about? • 5o. • 15o. • 25o. • 35o.

49. Questions • Which of the following will NOT REDUCE the Stalling Speed? • Extra Weight. • Larger Wing Area. • Flaps Lowered. • Flaps Raised.

50. Questions • Where would you find the information regarding • the Aircraft’s various Stalling Speeds? • Pilot’s Notes. • Air Traffic Control. • Ground Crew. • McDonald’s.