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Strange solution tip for Q13142

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  • Strange solution tip for Q13142

    Approximately how long does it take to fly a complete circle during a horizontal steady co-ordinated turn with a bank angle of 45? and a TAS of 200 kt?
    Solution says:

    The formula to calculate the circumference of a circle is:
    C = 2 x Pi x r
    = 2 x 3,1415 x 1060 m = 6660 m

    speed = distance / time --> time = distance / speed
    TAS = 200 kts = 103 m/s
    6660 / 103 = 63 sec.
    Quite a long way to get the solution and you end up using "v" 3 times and 3 calculations. Another (and more accurate) way of simplifying the above is:

    (gtan45 * 57.3rads per second)/200kts*.514 = 64.58seconds

  • #2
    Re: Strange solution tip for Q13142

    Hi globalste

    Yes there are often many different ways to calculate questions, we try to reduce the number of formula that a student needs to remember. The ATPL syllabus requires the student to know Radius = TAS squared / g Tan bank angle.

    John H

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    • #3
      Re: Strange solution tip for Q13142

      Ok understood

      Comment


      • #4
        Re: Strange solution tip for Q13142

        I've a query about the radius calculation for this question. Isn't the radius equal to the speed squared in this example?

        As in 103m/s x 103m/s = 10609m

        The solution uses 1060m as the radius of the turn...

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        • #5
          Re: Strange solution tip for Q13142

          Hi trid

          The radius of turn = TAS squared / g x tan of bank angle . TAS must be in m/s and radius will be in m.

          The TAS squared = 10609 m/s ( 103 x103) that is not the radius.

          the radius = 10609 (TAS squared) / 10 ( g rounded up) x Tan 45

          Tan 45 = 1 so radius = 10609/10 = 1060.9 ?

          Hope this helps

          Regards

          John H

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          • #6
            Re: Strange solution tip for Q13142

            Yes, that's very helpful thank you!

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            • #7
              Hi all 1kt is 0.514 m/s NOT 0.515 just checked the CAA LO's and online. Also that radius equation does not apply here because, it is asking for how long it would take not, the distance.
              so it would be better to use ROT equation not R

              ROT equation then *57.3 to degrees/second then 360 degrees (full circle)/ previous answer in degrees per second= 64.58
              Last edited by freddymitchell; 22-02-2020, 18:11.

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