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
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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
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