ASCI 202 - Presentation Slides & Discussion.

Angle of attack is the angle of the relative wind to the chord line of the aerofoil - Chord line is the imaginary line from the leading edge to the trailing edge of the aerofoil - Drag is a factor in the angle of an ai ...

Angle of attack is the angle of the relative wind to the chord line of the aerofoil - Chord line is the imaginary line from the leading edge to the trailing edge of the aerofoil - Drag is a factor in the angle of an aircraft - Parasitic Drag - Not associated with the production of lift. - Induced Drag - Associated with the production of lift. - Implications of AOA - Speed - The higher the AOA, the slower the airspeed for the same given power - Attitude - As attitude increases, a pull force will result in a larger change in pitch angle resulting in an increasing angle of attack - Aircraft Weight - When weight is increased, the aircraft needs to fly at a higher AOA to produce more lift to oppose the increase in weight - CG - A forward CG will cause the aircraft to fly at a higher AOA. - Planes can stall at any speed as long as they exceed the critical angle of attack. - AOA indicators help to inform pilots of an imminent stall through audio or stick shakers. - The four forces of flight - Thrust - Force that propels a flying machine - Drag - Opposing aerodynamic force along the flight direction and can be either desirable or undesirable. - Lift - Force directly opposing the weight of the aircraft. Lift is generated when a moving flow of gas is turned by a solid object. Lift coefficient - CL = Weight/Dynamic Pressure (q) * Wing Area (S) - Weight - A force that is always directed towards the center of the Earth. - Mach number is a number that indicates the ratio of the speed of an object to the speed of sound in the medium through which the object is moving. - M = Velocity of Object (Object Speed/Speed of Sound) - Subsonic - Less than mach 0.8 (B737, A330) - Transonic - Between Mach 0.8 and 1.2 (777, 767) - Supersonic - Between Mach 1.2 and 5 (Concorde) - Hypersonic - Above Mach 5 (X-15) - A sonic boom occurs when an aircraft flies faster than the speed of sound (761 mph) - Higher temperature > Air molecules spread further apart > Less dense air; Air temperature is inversely related to air density - High ambient temperatures - Engine components reach maximum operating temperatures before the appropriate thrust setting is produced - Low air density - Reduced density of inlet air causes lesser airflow mass through the turbine, which causes lesser overall power output. - High ambient temperature and low air density - Higher density altitude - Decrease in generated lift - Increase in take-off distance (1% every 1 degrees Celsius) - Decrease in climb rate - Real-world implications due to hotter ambient conditions - Increased take-off distance - Limited runway length; Limited airport expansion - Increased engine power settings - Increase maintenance costs; Decreased service life - Reduced climb performance - Unable to meet obstacle clearance - Increased take-off weight restrictions - Factors affecting landing distance - Meteorological/Environmental Conditions - Surface Winds/Runway Contamination - Geographical Conditions - Aircraft Malfunction - Pilot Error - Types of wing planform - Rectangular Wings - Tapered Wings - Decrease in drag - Increase in lift - Swept Back Wings - Able to achieve high subsonic speeds - Less drag when flying - Delta Wings - Critical in achieving high lift for supersonic flights - Low aspect ratio, it induces high drag - Unstable at high angles of attack - Elliptical - Commercial aircraft mainly adopts the sweptback wing while fighter jets adopt the delta wing designs. - Axes of movement - Vertical Axis - Control Surface: Rudders - Instrument: PFD, Turn and Slip Indicator