G2,
Happy new year.
Any aerodyne will lose speed in a turn because, ceteris parabus, the supporting vector shifts from the straight and level position to produce a centripetal component. The frame of reference is the air mass within which it is flying.
Wind is only an earth-referenced concept.
Humans regularly injure themselves (ither physically or mentally) when they attempt dynamic activities in the incorrect frame of reference. I used to demonstrate this problem at reasonable speeds in the earth's boundary layer by getting the student to observe the IAS and attitude in turns flown on the clocks and then in turns flown by reference to the ground. They generally had no problem thereafter recognising that they had to actively prevent the visually-inspired desire to maintain a constant ground speed from interfering with the need to maintain air speed.
All and any reference to the issue should be to "the downwind turn illusion" so that the urban myths scattered throughout this forum and the minds of the ill-informed are contained rather than perpetuated.
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Stay Alive,
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