cwatters wrote:
I suspect the reality is somewhere between the two positions being taken on inertia.
I suspect this is right, too. However, I am sure from empirical means that the effects of intertia are very small. I have flown thousands of 360 degree circles at 45 degrees of bank and an IAS of 45kt, in airmasses which are moving at 30kt or more. It is possible to maintain an apparently steady airspeed doing this. If head/tailwind had any appreciable effect on airspeed I'd stall once on each orbit!
I can't believe that proximity to the ground makes any difference, and I have enough circles at 600 ft agl to know that, again, there are no detectable speed differences related to the wind direction and my heading.
My
guess is that the force of the aircraft's intertia (is it a force? Why is there never a physicist on hand when you need one?) operates at a tangent to the circle you are flying. Thus as you turn through 180 degrees the inertial force is at all times nearly aligned with your heading, so that for practical purposes you can assume no headwind/tailwind difference.
Losing airspeed because of the higher induced drag in the turn is an entirely different matter - this would equally be a problem turning from downwind to headwind.