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Uncontrolled copy not subject to amendment

Uncontrolled copy not subject to amendment. Principles of Flight. Principles of Flight. Learning Outcome 1: Know the principles of lift, weight, thrust and drag and how a balance of forces affects an aeroplane in flight Part 2. Principles of Flight. Revision. Questions.

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  1. Uncontrolled copy not subject to amendment Principles of Flight

  2. Principles of Flight Learning Outcome 1: Know the principles of lift, weight, thrust and drag and how a balance of forces affects an aeroplane in flight Part 2

  3. Principles of Flight Revision

  4. Questions • Newton’s 3rd Law States: • Every object has weight. • Weight equals lift during flight. • Every action has an equal and opposite reaction. • Every force causes an object to move.

  5. Questions • In which direction does LIFT operate relative to airflow? • Parallel to it. • Perpendicular (at 90o) to it. • c. Straight up. • d. Straight down.

  6. C A B Questions What has happened to the air pressure at point ‘B’? • It is greater than at point ‘A’. • It is greater than at point ‘C’. • It is the same as point ‘C’. • It is lower than at point ‘A’.

  7. Drag and Thrust Objectives: 1. Explain Drag and Thrust. 2. Describe the effect that Streamlining has on Drag. 3. State the effect that Airspeed has on Drag. • Describe the relationship between Drag and Thrust when an aircraft is: a. At Constant Speed. b. Accelerating. c. Decelerating.

  8. Drag and Thrust Lift Thrust Drag Weight

  9. How do we produce Thrust? Propellers Jet Engines Thrust

  10. Remember Newton’s 3rd Law? The engine achieves this by “pushing” the air backwards from either through a propeller or from the rear of a jet engine. The amount of Thrust depends on engine size, etc. Thrust

  11. Drag What is Drag? Remember riding a bicycle into a wind or riding faster? PHEW!!

  12. Variation of Drag with Airspeed The amount of Drag varies with the square of the Airspeed. So, Double the Airspeed, then Drag is Four times as much! Triple the Airspeed, then Drag is Nine times as much! Drag Airspeed

  13. Airflow Drag Drag is the force which hinders your progress. The faster you go the more drag you feel. We need Thrust to overcome the Drag. Consider: Maximum Drag. 20 “people” needed on “the team”.

  14. Airflow Drag What happens we pull a ball of the same diameter as the plate? Drag is reduced by 50%. Now only 10 “people” needed on “the team”.

  15. Airflow Drag What happens we ‘streamline’ a shape of the same diameter? Drag is reduced to 5%. Only 1 “person” needed on “the team”.

  16. VERY TURBULENT WAKE REDUCTION IN FORM DRAG 50% 85% 90 - 95% Form Drag

  17. Drag This type of drag is “Form Drag”, ie the shape of the object. So do we need: OR? This Shape? This Shape? Reducing Drag, reduces the amount of Thrust required!

  18. Examples of Streamlining

  19. Surface Friction Drag Boundary layer Total surface area Viscosity of the air Thickness of the boundary layer Surface friction drag is reduced by smooth surfaces

  20. Interference Drag Reduced by adding fairings

  21. JSF

  22. 1. Form Drag (The Shape) Flat Plate 100lbs drag Streamlined Shape 5lbs drag 2. Surface Friction Drag (Smooth/Rough) Smooth - 4lbs drag Rough - 6lbs drag 3. Interference Drag 11lbs drag 5lbs drag Zero Lift Drag

  23. Low Pressure Low Pressure Lift Dependent Drag Relatively High Pressure

  24. TIP VORTEX SPILLAGE Formation of Wingtip Vortices

  25. HIGH SPEED LOW SPEED SMALL VORTEX LARGE VORTEX Effect of Speed on Wing Tip Vortex

  26. LOW ASPECT RATIO CHORD CHORD LARGE VORTEX SMALL VORTEX Effect of Aspect Ratio on Wing Tip Vortex HIGH ASPECT RATIO

  27. Vortex Drag

  28. Drag Drag has several components as the following “Tree” will illustrate: Vortex Drag Surface Friction Drag Form Drag Interference Drag Lift Dependent Drag Zero Lift Drag Total Drag Increments of Zero Lift Drag

  29. TOTAL DRAG VIMD Drag Drag can be represented by the following graph: DRAG ZERO LIFT DRAG LIFT DEPENDENT DRAG IAS

  30. Thrust and Drag in Straight & Level Flight Aircraft Accelerating: What is the difference between Thrust and Drag? Thrust is Greater than Drag

  31. Thrust and Drag in Straight & Level Flight Aircraft Decelerating: What is the difference between Thrust and Drag? Drag is Greater than Thrust

  32. Thrust and Drag in Straight & Level Flight Aircraft Constant Speed: What is the difference between Thrust and Drag? Thrust = Drag

  33. Straight & Level Flight For Straight & Level Flight at Constant Speed ALL Forces are in Balance Lift Thrust Drag Weight

  34. ANY QUESTIONS?

  35. Drag and Thrust Objectives: 1. Explain Drag and Thrust. 2. Describe the effect that Streamlining has on Drag. 3. State the effect that Airspeed has on Drag. • Describe the relationship between Drag and Thrust when an aircraft is: a. At Constant Speed. b. Accelerating. c. Decelerating.

  36. Questions What is the force called that drives an aircraft forwards? Lift Weight Drag Thrust

  37. Questions What is the force called that resists the forward motion of an aircraft? Lift Weight Drag Thrust

  38. Questions If you speed is doubled, by how much would the Drag be increased? x2 x4 x6 x8

  39. Questions If Thrust= Drag and Lift=Weight then the aircraft is: Climbing Flying Straight & Level and Accelerating Flying Straight & Level and Decelerating Flying Straight & Level at Constant Speed

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