Granted, the forward airspeed should have been taken into account as well, however, with those speeds taken into account for the advancing and retreating sides of the disc, its just exasserbates the overall issue. I think that as the fuselage turns thorugh 180 degrees, its the inflow roll that causes the disc from the pilots view point to flap up, leading to a nose up attitude to develop unless the pilot does stuff. Hence lose speed/need more power in the turn to maintain the original into wind speed.....
The above theory works for a helo with a clockwise head (when viewed from above) turning at low speed to the right - still working the idea otherwise..
