ORIGINAL: Andrew McGregor
ORIGINAL: mesae
ORIGINAL: Jet A1
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As the glider has a mass and the inertial system for this is earth, the mass will be accelerated when turning from headwind to tailwind....
The aircraft does not "feel" this supposed acceleration.
The airborne glider is acting not directly against the earth, but rather on the atmosphere. Its reference frame for performance is the air.
Mass has no reference frame, first problem here.
Second, aircraft do feel the acceleration turning downwind... but it's no different than turning crosswind or any old turn at the same bank angle in still air, for that matter. It's kind of hard to see this with a model, but if you turn into a constant bank angle turn, you fly a helical course with the spacing of the turns being how far the wind carries you downwind (I've actually done this with a fullsize power plane and measured the spacing... it was a very windy day so it was nearly a mile per 2-minute turn... the math all worked out, of course). Flying in circles in still air is a special case of this.
If you are trying to counter my statement that the airplane does not feel the earlier referenced acceleration, then you misunderstand me. Your post seems to read as though you are trying to correct me, but I believe we agree perfectly. I'm a full-scale pilot too: a 4700 hour ATP. You make exactly the same points I've been trying to make, namely that airplanes in constant bank turns feel the same acceleration regardless of wind speed or direction (in steady wind). The exercise you described is an excellent way to illustrate this point, and also to measure wind velocity (your wind was a little less than 30 knots, though you didn't report the direction of drift).