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Principals O f Flight

Principals O f Flight. Scenario: Today we will be discussing the principals of flight, covering how aircraft fly, different wing designs, drag, lift, turning tendencies in an aircraft and wake turbulence. . Objective.

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Principals O f Flight

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  1. Principals Of Flight Scenario: Today we will be discussing the principals of flight, covering how aircraft fly, different wing designs, drag, lift, turning tendencies in an aircraft and wake turbulence.

  2. Objective To determine the applicant exhibits knowledge of the principals of flight by describing: Airfoil design and characteristics, Airplane stability and controllability. Turning tendency. Load factors. Wing tip vortices and precautions to take. Principles of flight - YouTube

  3. Newton's 3 Laws When a body is in motion it stays in motion, and a body at rest will stay at rest till a force is applied to the object. When a force is applied to an object, the acceleration is proportional to the mass and force of the object. ( F=MxA) For every action there is an equal and opposite reaction.

  4. Four Forces • During all phases of flight there are four forces on an aircraft. • Thrust :opposing drag. • Drag: opposing thrust. • Lift: opposing Weight or gravity • Weight: Opposing lift.

  5. Four Forces • Straight and level un accelerated flight everything is in equilibrium. Lift = weight and thrust = drag. • To enter a climb lift must be momentarily increased to over come weight. • To speed up thrust must be momentarily increased to over come drag.

  6. Three Axis Aircraft have three axis of rotation. A combination of these are what allow us to fly and maneuver the aircraft.

  7. THREE • As we just discussed an aircraft has THREE axis of rotation which are all controlled by the THREE primary flight controls: • Ailerons (Roll, longitudinal axis) • Elevator (pitch, lateral axis) • Rudder (yaw, vertical axis) Chuck Coleman Aerobatic Flying in his Extra 300 - YouTube

  8. Bernoulli's Principal As water is forced into a confined space two things happen. Velocity is increased. An area of low pressure is formed.

  9. Bernoulli’s Principal So why does this work with the atmosphere and apply to an aircraft?

  10. Newton's 3rd law of motion For every action there is an equal and opposite reaction. As air is pushed downward, the aircraft is pushed upward.

  11. Airfoils An airfoil is any surface that creates a aerodynamic force when coming in contact with moving air. Leading Edge: Beginning of the airfoil Trailing Edge: The last surface area to come in contact with the moving air. Chord Line: imaginary line connecting the leading edge to the trailing edge. Camber:is the airfoils curvature both on the upper and lower surface. Relative wind: the wind opposite the flight path of the aircraft. AOA: Angle between chord line and relative wind.

  12. Airfoils

  13. Wing Designs Aspect ratio: This is the ratio between the wings length, and the width. Wing Area: The total surface of the wing, how much surface area is exposed to the air. Angle of incidence: Angle at which the wing meets the fuselage. We can not change this. Plan Form: How the wing appears when viewing it from above, or below.

  14. Aspect Ratio

  15. Wing designs Some wing designs will cause the wing to stall at the roots and move outward. others will stall at the tips and move inward.

  16. Stalls • Every airfoil has a critical angle of attack. • Angle at which smooth airflow is disrupted over the top of the airfoil. • Stalls have nothing to do with airspeed. Only AOA.

  17. Stalls • As you approach the Critical Angle Of Attack the airflow begins to separate and actually flows backward, resulting in a Huge increase in drag!! Airflow during a stall. - YouTube

  18. Lift • Lift can actually be controlled by the pilot by doing several things: • Lift is the square of your airspeed,so you can increase/decrees lift by speeding up, or slowing down. • Changing your AOA • Changing the wing shape and or area by adding flaps or other high lift devices. • Also, pressure, temperature and humidity can affect lift.

  19. Lift • Aircraft lift is not in just an upward direction. • Lift also occurs in a horizontal, path this is what enables the aircraft to turn. • Vertical component • Horizontal component

  20. High lift devices High Lift devices: Trailing Edge flaps Leading Edge flaps Leading Edge Slots Leading Edge Slats Canard

  21. Drag Parasite Induced • Three forms: • Skin Friction Drag. (Surface of the aircraft) • Form Drag. (LDNG gear, antennas) • Interference Drag. (where wing meets fuselage) • A function of Lift. This type of drag is only formed as the aircraft is creating lift and will decrease as your airspeed increases. • This drag is created due to our induced AOA and airflow disruption.

  22. Parasite Drag • Works opposite thrust and comes in three forms: • Form • Skin friction • Interference As speed grows parasite drag grows

  23. Induced • Works opposite thrust and is a product of lift. • Created by the induce AOA and airflow separation as AOA grows greater. slower airspeeds greater induced drag.

  24. 90 Degrees

  25. Drag

  26. Aircraft stability Stability: the tendency for the aircraft to return to straight and level flight. (Positive, Neutral and negative) Two types: Static Dynamic

  27. Aircraft Stability static dynamic • This stability refers to the initial reaction for your aircraft. • Does it want to return to starting position. • Stay where it is at. • Or continue to grow in the movement you just applied. • This stability refers to your aircrafts motion over a length of time. • Does it want to return to starting position. • Stay where it is at. • Or continue to grow in the movement you just applied.

  28. Aircraft Stability

  29. Aircraft Stability There can be a few different ways that your aircraft can either be stable, or unstable. Longitudinal stability: Whether the airplane will want to pitch up, or pitch down. Lateral Stability: Whether or not the wings will want to roll left/right or stay level.

  30. Controllability How easily a body responds to control inputs controllability is affected by the location of your C.G (center of gravity)

  31. Controllability AFT C.G FORWARD C.G • Not as stable • More controllable • Lower Stall speed. • Higher cruise speeds. • More stable • Less controllable • Higher stall speed. • Lower cruise speeds.

  32. Load Factors Any force that attempts to move an aircraft from its flight pathwill impose a certain amount of “load” or G forces on an aircraft. Newton's 1st law..

  33. Load Factors This is important to know for two reasons: It is possible for a pilot to impose to much stress or to many “G” forces on an aircraft and damage the aircraft structure. An increase in load factor will increase the stall speed, making it possible to stall at an airspeed that seems perfectly safe.

  34. Load Factors Once you reach a 45 degree bank angle any further bank increase will rapidly increase both the “G” loads imposed on an aircraft and stall speed.

  35. G loads and stall sped

  36. Load Factor

  37. Turning Tendencies Our aircraft always wants to turn left to some degree especially in a climb. This is due to the effects of: P-Factor Torque Spiraling Slipstream Effect

  38. Turning tendencies P-Factor Spiraling Slip Stream

  39. Turning tendencies Torque

  40. Wingtip Vortices Wingtip Vortices are a production of lift, only created when the aircraft is producing lift. Greatest when aircraft is clean, slow, high angles of attack. (Takeoff) They flow outward and downward. They like to hang around for a few minutes

  41. Wingtip Vortices

  42. Wingtip Vortices: How to avoid wake turbulence: Land after. Takeoff before. Side step if able Stay slightly above

  43. Ground Effect When within 1 wingspan distance from the ground this phenomenon starts to occur. When within ½ wingspan from the ground this becomes very apparent and noticeable. During takeoff the aircraft may seem ready to fly when it actually is not. (always accelerate to VR) During the landing flair any excess speed may expose you to a very long float down the runway.

  44. Ground Effect Occurs due to the interference from the ground. Ground interferes with airflow around the wings (up/down wash and wingtip vortices) Airplane experience a reduction in drag and increased lift.

  45. Ground Effect Reduction in the induced AOA

  46. Ground Effect • Vortices create drag and reduce lift, by reducing the vortices you decrees drag and increase lift.

  47. Multi-Engine Aerodynamics • Single engine ops we have 2 main concerns: • Maintaining directional control. • Reducing drag. • 50% loss in thrust. • 80% loss in performance.

  48. Multi-Engine The effects: Pitch down around the lateral axis. Roll around the longitudinal axis towards the dead engine. Yaw around the vertical axis toward the dead engine.

  49. P.A.S.T P-factor Asymmetrical thrust,accelerated slip stream Spiraling slip stream Torque

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