JCRAN,
that helps, like always, thank you.
I was wondering is the use of a supercritical airfoil could be justified at the very tip of a blade, combined with a vortex fence (short anhedral).
The APACHE and Black Hawh blades seem to have that kind of airfoil or am i wrong ? at least those blades have a sudden change in twist at the tip.
what do you think ?
thanks for the link, indeed the airflow shape is scaring !
i really wonder how a 2d study is usefull , unless you apply a lot of empirical corrections..alas i have not acces to a full 3D airfliw simulation software.
Thank you