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  • Airplanes and Aerodynamics
    AVIATION/CPL
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    Summary

    1.1 Flaps

    Main functions : During approach and landing, increase angle of attack. causes the wing to produce the same amount of lift at a slower airspeed.


    1.2 Airplane Wings

    Spoilers
    many mordern turbojets have, top of the wing can be deployed automatically or PIC to disrupt airflow and destroy lift
    just after landing, spoiliers allow the brakes to be more effective.

    Rectangular wings
    generally are designed. root stalls first with the stall progression toward the wingtip.

    change in the angle of attack of the wing, lift, drag, airspeed changed.

    angle of attack of wing directly controls the distribution of positive and negative pressure acting on the wing.

    Frost on the upper wing disrupts the smooth airflow => increases drag
    and causes the airplane to stall at higher airspeed and lower angle of attack than normal => stall speed incareses


    1.3 Stalls

    Angle of attack remains constant regardlees of [ Weight / Dynamic pressure / Bank angle / Pitch attitude ]

    Stall speed is Affected by [ Wiehgt / Load factor / Power setting ]

    Tubulence can increases stall speed due to increased load factors.

     

     

    1.4 Spins

    Recover from spin, may become difficult when the CG is too far rearward.

    Rotation of aa spin is always around the C.G

     


    1.5 Lift and Drag

    wing produces lift, Higher pressure below the wing, lower pressure above the wing

    Lift is force acting perpendicular to the relative wind.

    increase in the angle of attack wll increase drag. ( drag acts paraleel to the flight path)

    In all staday state flight, Sum is same(forward = rearward, upward=downward)

     

    Angle of bank increase => vertical compnent of lift decreases and the hoizontal lift increases.

     

    airspeed increase => lift, parasite drag increase, as suare of the increase in airspeed

     

    induced drag is byproduct fo lift, also greatly affected by changes in airspeed

     

    * drag diagram

    As Airspeed increase, total drag increases due to the increased parasite drag.

    As airspeed decrease, total drag increase due to increased inducred drag

     L/D Max is the minimum point of the total drag curve.

     


    1.6 Ground Effect

    due to the interference of the ground surface with the airflow patterns

    within distance of its wingspans to the surface.

    change alters the wing's upwash, downwach, and wingtip vortices.

     

    leaving ground effect zone, increase in induced grag and requires more thrust.

    in ground effect needs a lower angle of attack to producxe the same lift as when out of ground effect. 

     


    1.7 Airplane Stability

    inherent ability of an objet

    return to its original potsition.

    ex ) in turbulent air

     

    Stactic stability : Positive - Neutral - Negative

    Poitive : return to original position

    Neutral : no tendency

    Negative : continue to move directionof the force

     

    Dynamic stability

    Positive : oscillation become smaller and smaller, settles down

    Neutral : oscillationss remain unchanged

    Negative : oscillatiions tend to increase.

     

    in airplane

    Longitudinal stability about lateral axis

    Lateral stability about ongitudinal axis

    Directional stability about the vertical axis

     

    rear of CG range, will tend to be unstable about lateral axis

     


    1.8 Turns

    increase ins airspeed in turn, increase in the radius, decrease rate of turn.

     

    contant bank angle, load factor will be constant ergardless of

    rate of turn / airpseed / weight

     

    as bank increased => additional vertiacl lift convert to horizontal lift, decreasing vertical lift

    => need increasing angle of attack

     

    standard rate of turn : 2min. for 360 degree. 3degree / sec.

     

     

    1.9 Load Factor

    ratio between the total airload on the wing, gross weight of the airplane

     

    increase load factor will cause an airplane to stall at higher airspeed

     

    as bank angle increase, load factor will increase. 

     

    Load factor is multipe of the weight x gravity

     

    60 degreee bank has load factor of 2.0

     


    1.10 Transonic and Supersonic Flight

    ratio of ture airspeed in kts to the speed of sound in kts.
    => Mach number

    subsonic : below 0.75

    transonic : 0.75 - 1.20 

    super sonic : 1.2 - 5

    hyper sonic : above 5

     

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