Sorry, and with all due respect, the helicopter does not care about the ground as a reference point. (unless you hit it)
Inertia measured relative to the ground is not valid....just as it is not valid to say that a helicopter hovering at the equator has more energy then one hovering at the pole.
Sure it does from the frame of reference to an interstellar object....but that does not have any effect on the dynamic of flight.....Just as a frame of reference to the ground has no effect.
AIRSPEED is the the only measurement that matters to a flying object. It does not care if you turn upwind or downwind....so long as airspeed stays the same.
Like I said earlier.....it is possible that climbing or descending through a gradient CAN have a effect or flying in gusty conditions. This can add or decrease energy from the ship.....relative to it's airspeed.....which is the only one that matters.