L2 Driver, do your comments apply to a constant circular turn (ie constant attitude, IAs etc) or a constant orbit relative to the fixed point ?
If the latter then I fully agree that power changes will be needed. But I am still struggling to see how they are needed for a constant rate turn (except the initiation of the turn).
I see where you are going. You are right in that you have to increase power to make up for lost ground speed when flying into the wind and decrease power flying with tailwind to make that circle circular. That is however not what I am talking about. I am talking about the need to release stored energy (engine power or altitude) to keep your IAS in relation to the air around you to keep you flying safely.
If you are flying a constant f. ex 45 degree banked turn without any fixed ground references, the the energy requirement will change constantly during the turn. They will increase turning downwind and decrease turning upwind. This is of course only valid during accelerations (Acceleration= velocity vector change, not only speed change). This is due to the fact that we live on Earth, and all accelerations need energy.
I have experienced this a lot of times flying compass swings on the AS332L2, where you are required to keep a constant bank of 30 degrees and thereafter 45 degrees in both directions with a constant airspeed. I have done this at 50 kts winds and I can assure you that even when using autopilot, the required power, manually or automatically, changes a lot during the turn.
So if you want to keep a very constant IAS and complely level altitude, you need to vary your engine power. Simple as that.
