Presentation is loading. Please wait.

Presentation is loading. Please wait.

Uncontrolled copy not subject to amendment Principles of Flight.

Similar presentations


Presentation on theme: "Uncontrolled copy not subject to amendment Principles of Flight."— Presentation transcript:

1 Uncontrolled copy not subject to amendment Principles of Flight

2 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? a.Higher. b.Lower. c. The same. d. No difference.

5 Questions One type of Leading Edge Flap is: a.Plain. b.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: 1.Describe the Stall in terms of Lift. 2.State the generally used Critical or Stall Angle of Attack. 3Understand the relationship between Stalling and Airspeed. 4.State where the Pilot obtains information regarding the Aircraft’s Stalling Speed. 5.List the Factors which affect the Stalling Speed.

8 Stalling It is ESSENTIAL that 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 Remember the Lift Formula? Lift = C L ½ ρV 2 S If we slow down (reduce V) we must keep Lift the same (for Straight & Level Flight) by increasing C L. The Limit is C LMAX, so the Equivalent speed is V MIN (stalling speed) Lift = C LMAX ½ρV 2 MIN S Cl Max α Stalling Crit AOA ~ 15 o

10 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. Stalling Speed

11 The Mechanism of Stalling

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

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

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

15

16 Factors affecting stalling speed Aircraft Weight

17 EFFECT OF WEIGHT Lift BASIC WT = C L MAX ½ ρ V 2 BASIC STALL S Lift HEAVY WT = C L MAX ½ ρ V 2 HEAVY STALL S 

18 EFFECT OF WEIGHT = Lift BASIC WT C L MAX ½ ρ V 2 BASIC STALL S Lift HEAVY WT C L MAX ½ ρ V 2 HEAVY STALL S

19 EFFECT OF WEIGHT Lift BASIC WT V 2 BASIC STALL Lift HEAVY WT V 2 HEAVY STALL = V 2 BASIC STALL = V 2 HEAVY STALL X LIFT HEAVY WT LIFT BASIC WT LIFT HEAVY WT LIFT BASIC WT V 2 HEAVY STALL = V 2 BASIC STALL X

20 LIFT HEAVY WT V 2 HEAVY STALL = V 2 BASIC STALL X LIFT BASIC WT V STALL HVY = V STALL BASIC X LIFT HEAVY LIFT BASIC EFFECT OF WEIGHT V STALL HVY = V STALL BASIC X Weight HEAVY Weight BASIC

21 Factors affecting stalling speed Pulling ‘g’

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

23 ’ EFFECT OF ‘G’ Danger 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 Weight Lift Thrust Flight Path EFFECT OF THRUST ON STALLING

26 Weight Thrust LiftLiftLift TR Flight Path EFFECT OF THRUST ON STALLING

27 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 C LMAX FLIGHT PATH

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

29 NATURAL STALL WARNING NORMAL FLIGHT TURBULENT AIR MISSING TAILPLANE

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

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

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 Relative Airflow Chord Basic ‘Clean’ Situation α

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

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

38 Cl Max AT STALL: WEIGHT = LIFT = C LMAX ½ρ V 2 STALL S EFFECT OF FLAP Critical Angle Without Flap AoA CLCL

39 AT STALL: WEIGHT = LIFT = C LMAX ½ρ V 2 STALL S IF THIS IS THIS IS CONSTANT MORE LESS EFFECT OF FLAP Critical Angle With Flap Cl Max More AoA CLCL Nose lower at Stall Without Flap Cl Max

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: 1.Describe the Stall in terms of Lift. 2.State the generally used Critical or Stall Angle of Attack. 3Understand the relationship between Stalling and Airspeed. 4.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? a.Lift Increases as Angle of Attack Decreases. b.Lift Decreases as Angle of Attack Increases. c.Lift is Greatly Reduced. d.Lift Remains unchanged.

48 Questions The Critical Angle of Attack is Generally about? a. 5 o. b.15 o. c.25 o. d.35 o.

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

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

51


Download ppt "Uncontrolled copy not subject to amendment Principles of Flight."

Similar presentations


Ads by Google