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Straight & Level Aim: To learn the principles and considerations of straight and level flight, and how to maintain it Application: •Used in the cruise segment •Shortest distance between two points •Improve passenger comfort Overview • Revision • Definitions • Principles • Considerations • Air Exercise • Review Revision • Control Effects Revision • Control Effects • Bernoulli’s Theorem PT = PD + PS Revision • Control Effects • Bernoulli’s Theorem • Lift L AoA IAS L = CL ½V2 S AIRSPEED L Revision • Control Effects • Bernoulli’s Theorem • Lift • Aerofoil Definitions • Centre of Pressure (CoP) The total reaction of the aerodynamic forces around the aerofoil can be considered to act through the CoP + _ Lift Definitions • Centre of Gravity The point through which the entire aircraft weight acts Definitions Lift • Lift is produced by a pressure differential • Acts perpendicular to the relative airflow through the centre of pressure Weight • Acts vertically downwards towards the centre of the Earth • Equal to mass x gravity Definitions Thrust • Produced by the propeller through the propeller shaft Drag • Opposes thrust, enemy of flight • Parallel to the relative airflow Definitions • Moment Equal to force x distance Definitions SUMMARY Weight Drag Thrust Lift Principles Couple Moments • Caused by the interaction of the two forces separated by a horizontal distance Weight Thrust Drag Lift T/D couple L/W couple Elevator down force. Pivot Point Principles DRAG Two Main types: 1. Parasite Drag 2. Induced Drag Principles Parasite Drag • Skin Friction DRAG due to FRICTION FORCES Principles Parasite Drag • Skin Friction • Form Drag DRAG DRAG DRAG due to FLOW SEPARATION Principles Parasite Drag • Skin Friction • Form Drag • Interference Drag Principles Parasite Drag Follows the “SQUARE RULE” Parasite Drag Low speed cruise High speed cruise EXAMPLE •If we double our airspeed then we will have 2 x 2 the drag 4 Times the drag Principles _ _ _ _ _ _ _ _ + + + + + + Low Pressure High Pressure VORTICES Induced Drag • Is a by-product of AoA Principles INDUCED DRAG INCREASES WITH DECREASING SPEED Induced Drag Airspeed High AoA / Low IAS Induced drag Low AoA / High IAS Induced drag Principles TOTAL DRAG - Summary Slow Fast DRAG AIRSPEED Induced Drag Parasite drag TOTAL DRAG Minimum Drag Best L/D Ratio Considerations • Stability Displacement Displacement Ball returns STABLE Displacement UNSTABLE Ball remains NEUTRAL Considerations LONGITUDINAL STABILITY Considerations LATERAL STABILITY Lift Weight Pendulous effect of offset lift and weight corrects the roll. Lift Horizontal lift component causes a side slip. Relative airflow strikes the down going wing at a higher AoA which corrects the roll. Considerations DIRECTIONAL STABILITY Aerodynamic Force Air Exercise • Slow Cruise • 1800RPM + 2 fingers 80KIAS • Normal Cruise • 2100RPM + 4 fingers 110KIAS • Fast Cruise • 2300RPM + 5 fingers 120KIAS • From Climb From Descent Monitor – Using Attitude Lookout Attitude Performance Airmanship • LOOKOUT • Smooth throttle and control movements • Correct Handover/Takeover procedure • Monitor engine gauges Review Review Slow Fast DRAG AIRSPEED Induced Drag Parasite drag TOTAL DRAG Minimum Drag Best L/D Ratio |
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