Tailwind effects on lift during a microburst
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Tailwind effects on lift during a microburst
Hello guys ,
According to the principles of flight book i understood that only GS is affected by wind changes which is TAS corrected for wind, and the indicated airspeed remains constant .
According to the lift formula , lift is half density times TAS squared times S times Cl .
1: I know engine performance decreases with a tailwind , but how lift is lost during an approach with a high tailwind if my lift formula is not affected since my indicated airspeed is constant and everything else in the formula did not decrease ?
2
oes my indicated airspeed decrease in a tailwind or microburst and increase in a headwind or it stays constant ?
3: The book mentioned that airspeed dangerously drops during a micro burst so we try to compensate that drop with more pitch up and thus stall . What airspeed they are talking about ?
Thanks
According to the principles of flight book i understood that only GS is affected by wind changes which is TAS corrected for wind, and the indicated airspeed remains constant .
According to the lift formula , lift is half density times TAS squared times S times Cl .
1: I know engine performance decreases with a tailwind , but how lift is lost during an approach with a high tailwind if my lift formula is not affected since my indicated airspeed is constant and everything else in the formula did not decrease ?
2
oes my indicated airspeed decrease in a tailwind or microburst and increase in a headwind or it stays constant ? 3: The book mentioned that airspeed dangerously drops during a micro burst so we try to compensate that drop with more pitch up and thus stall . What airspeed they are talking about ?
Thanks
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1. A tailwind causes less air over the wing reducing lift. IAS is proportionate to the air around the wing. No air - no IAS.
2. IAS will decrease with a tailwind - refer to 1.
3. Not sure what book you're reading but that's very vague. Firstly, you wouldn't go anywhere near a microburst. If you're unfortunate to encounter one, you would reduce your speed to the turbulence penetration speed or worst case scenario and dropping like a stone, pitch right up just before the stick shaker (that is possibly why the book's author mentions a pitch up).
2. IAS will decrease with a tailwind - refer to 1.
3. Not sure what book you're reading but that's very vague. Firstly, you wouldn't go anywhere near a microburst. If you're unfortunate to encounter one, you would reduce your speed to the turbulence penetration speed or worst case scenario and dropping like a stone, pitch right up just before the stick shaker (that is possibly why the book's author mentions a pitch up).
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1. Your TAS quantify the relative speed between the aircraft and the surrounding air mass. So when flying with a tailwind, the plane is moving, but the air is also moving in the same direction...so the relative speed decreases as well as TAS and Lift.
2. It decreases with tailwind and increases with an headwind. See above.
3. It is true for every airspeed but the GS. You can assume he's talking about TAS or IAS if you prefer.
Edit: Of course you increase your pitch to increase alpha (->Cl) to compensate for the loss of TAS. This is true until the stall point, where an increase of the alpha angle produces a decreased Cl value.
2. It decreases with tailwind and increases with an headwind. See above.
3. It is true for every airspeed but the GS. You can assume he's talking about TAS or IAS if you prefer.
Edit: Of course you increase your pitch to increase alpha (->Cl) to compensate for the loss of TAS. This is true until the stall point, where an increase of the alpha angle produces a decreased Cl value.
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Try this for an explanation: https://www.youtube.com/watch?v=FxXw...YK0vhB&index=4
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