PaulisHome, hate to tell you but
Heston, as are you with
But if your groundspeed is changing, you will be accelerating. Even if the airspeed stays the same. And no matter what speed the wind is.
are incorrect.
You are not accelerating. There are two frames of reference, in both of which Newtonian physics apply. One frame is the earth, the other is the airmass, and for an aircraft in flight the relevant frame is the airmass. The only acceleration an aircraft experiences when making a turn, while maintaining a constant airspeed, is that of "g" in its vertical axis, being 2 "g" for a balanced 60° banked turn. Have a read up on Galilean invariance.
eckhard in his post re the model in a train exemplifies exactly the Galilean invariance.