I can not believe some of you guys are serious.
I am serious. Maintaining
constant airspeed well within performance limits in a
relatively gradual turn with lift to spare is one thing, and I agree with you... wind direction makes no difference. This is not the case here.
Making a very tight 180 turn at a steep bank like the helicopter that started this thread will require a huge amount of extra lift to maintain altitude, due to g loading (as Brian Abraham also said). For a time at the apex of the turn (at 90 degree bank or more), there is no vertical lift component relative to the ground, since the rotor is on its side... the aircraft wants to descend. Bear in mind also loss of forward velocity (read; airspeed), converted into centripetal force in making a turn like this.
If the aircraft is to complete the turn and maintain or regain level flight, in the absence of enough spare available power for lift, it needs more airspeed. Will it gain this more quickly with a 30kt wind up its ar*se or 30kts into its face? When exiting a steep 180 turn downwind like this it has less airspeed than the identical manouevre made into wind. It takes more time to accelerate to the required airspeed, whilst still subject to the same value of gravity. Hence it will lose more height. The altitude lost is
not the same: the amount of air travelled through to regain lift is the constant.
Maybe someone else can explain it better than I have.... anyone got any crayons?