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egger wrote at 2012-10-29 00:33:08
Here is how I look at it. An aircraft in steady, level flight has lift equal to weight and thrust equal to drag. Steady wind does not affect the aircraft aerodynamics, it only changes the ground speed. An aircraft that flies at 200 kts in still air and sees a steady 50 kt tail wind will fly at 250 kts over the ground, but the wings must see airflow at 200 kts to get the same lift and drag as before.



But if an aircraft sees a change in wind speed it will react to it as if it were a gust. If an aircraft encounters a sudden head wind, it will see increased airspeed over the wings and will climb temporarily, but the drag will go up so the climb will taper off, airspeed will decrease and the aircraft will achieve level flight again at the original airspeed relative to the air around it, but will be at a higher altitude than before (assuming the pilot does not correct).



A model airplane making a sharp turn from a tail wind to a head wind will respond in the same way. In the turn it will sink because the lift vector is not vertical. But when the aircraft first sees the head wind it will climb temporarily for the reasons stated above and increase altitude. When turning from a head wind to a tail wind, the aircraft will sink temporarily and then level off.



Propeller thrust is also affected by a gust, but it does not change the outcome.


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