No, you missed my point. In the example I gave the idea was to MAINTAIN 20 k IAS, , ie effectively hovering into wind and then (with the same forward cyclic position which gave 20 kIAS ) allowing the heli to accelerate when turning it downwind to try and maintain that 20 K IAS The IAS WILL fall as the machine accelerates to a groundspeed of 40 K whilst recovering that 20 K IAS, with some loss of translational lift, and resultant sink if power/torque is not added ! The sink and some loss of some (translational)lift is caused by turning downwind.

The retreating blade IS a high speed phenomenon but contrary to what someone else said a heli. is not always, at all parts of the disc, away from the stall, (or at least loss of lift because the blade angle may not be at a value at which it stalls, it is merely too slow to produce significant lift or may even suffer from reverse flow if speed is high enough) .

Of course my CFS(H) instructors at Tern Hill back in the '60s COULD have been teaching a load of rubbish or my memory really has gone to pot, but as I seem to recall that no one seems to have told the Bell 47 (Sioux in RAF speak) that the downward turn was a myth, ! !

On fixed wing is not something I have noticed !

Regards, David.