Lu,
To my knowledge (Tmk
), no one has yet built a blade with full Active Blade Twist.
Tmk, the ABT methods that are currently being experimented with are slow to reposition and/or have only a few degrees of pitch change. Tmk, there aren't any blades with ABT in actual helicopters; if you exclude Kaman's long existing servo-flap rotor. Tmk, a tip flap control was being considered for Northrop Grumman's UCAR tailless concept featuring twin intermeshing rotors but this project was canceled in December.
Your question therefor becomes a hypothetical one.
The
" 0-degrees AOA to the relative wind", which you mention, may be Mart's personal feeling as to what would be optimal angle at the tip. Perhaps he would be the best person to answer your specific question.
The preliminary and crude calculations for the UniCopter show that for a full ATB (including reverse velocity) the blades must be able to twist from -16.8º to +10.8º. More information on this is at;
UniCopter ~ Control - Flight - Independent Root & Tip (IRAT) ~ Blade Pitch Settings
Dave