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  • Best climb angle/Best rate of climb

    Some of this section is a right brain ache...!!

    Please could someone clarify a point regarding the best rate of climb speed, Vy.

    I understand that if you extend flaps and/or landing gear, total drag of the aircraft is higher - which must influence the power avilable : power required ratio, and hence reduce overall Vy airspeed.

    However, apparently the same cannot be said when it comes to a heavier aircraft. Apparenty Vy then occurs at a higher airspeed...?!
    Why is this so?? Surely if the wings are required to produce more lift to support the increased weight, lift induced drag will also increase, so why is the situation different to my first point?!

    Many thanks for any assistance.

  • #2
    Re: Best climb angle/Best rate of climb

    Hi Jezz
    I assume you'll be coming to the brush up where I spend some time on this particular subject.
    If you can grasp the behaviour of the total drag curve and power required curve with changes in drag, altitude and temperature you will understand what happens to the speeds.
    Profile/parasite drag influences the right hand side of the drag curve and power required curve moving it up and left. Total drag and power required increase and the point where you pick off your best speed, Vx/Vy, decreases.
    Induced drag influences the left hand side of the drag curve and power required curve moving it up and right. Total drag and power required increase and the point where you pick off your best speed Vx/Vy increases.The total drag is unaffected by changes in altitude and temperature as an EAS but the power required curve (which is Drag x TAS) is affected by an increase in altitude and temperature. As the TAS increases the power required curve moves up asnd right and your best speed Vy increases as a TAS.
    I've got some nice animations that I use in the classroom that will help your understanding.

    Colin
    Last edited by colin; 17-02-2011, 08:28. Reason: data

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    • #3
      Re: Best climb angle/Best rate of climb

      Thanks, Colin. That's a bit clearer - it's all about the curves...!!

      I will indeed be at brush-up; I was hoping to attend in April, however my progress is slow compared to Mod 1, so more likely May.
      Last edited by jezzc100; 18-02-2011, 12:59.

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