Rate of Climb and Climb Gradient Question
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Rate of Climb and Climb Gradient Question
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I have been given some rate of climb and climb gradient data and am having difficulty calculating the true airspeed used. I would really appreciate some advice on where I am going wrong.
Example data @ ISA and sea level
Gross Climb Gradient = 0.2014
Rate of Climb = 2,590 ft/min or 25.57552 nm/hr
My solution
ROC = KTAS * sine(Gross Climb Gradient)
= KTAS * Gross Climb Gradient (sine dropped due to small angle approximation)
Leading to
KTAS = ROC / Gross Climb Gradient
= 25.57552 / 0.2014
= 126.988
~= 127
My problem lies with the known indicated airspeed, which is 125 KIAS. Can anyone point me to how 125 KIAS becomes 127 KIAS?
I have been given some rate of climb and climb gradient data and am having difficulty calculating the true airspeed used. I would really appreciate some advice on where I am going wrong.
Example data @ ISA and sea level
Gross Climb Gradient = 0.2014
Rate of Climb = 2,590 ft/min or 25.57552 nm/hr
My solution
ROC = KTAS * sine(Gross Climb Gradient)
= KTAS * Gross Climb Gradient (sine dropped due to small angle approximation)
Leading to
KTAS = ROC / Gross Climb Gradient
= 25.57552 / 0.2014
= 126.988
~= 127
My problem lies with the known indicated airspeed, which is 125 KIAS. Can anyone point me to how 125 KIAS becomes 127 KIAS?
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My problem lies with the known indicated airspeed, which is 125 KIAS. Can anyone point me to how 125 KIAS becomes 127 KIAS?
2590fpm x 60 / 6076 = 25.576 kts vertical speed.
Inverse Tan (0.2014) = 11.387 degrees.
25.576 / sin(11.387) = 129.5 kTAS.
Possible errors, in decreasing order of significance:
Pressure error (also known as position error)
Trigonometric error by dropping the sine
Rounding error in calculation
For in-flight purposes, it might look something like this:
My airspeed (IAS or TAS will do at sea level) is 125kts.
My required climb gradient is just over 20%.
125 x 20 = 2500fpm.
I need to achieve just over 2500fpm.