HELICOPTER: A rotorcraft with a power driven rotor system whose axis (axes) is (are) fixed and substantially perpendicular to the longitudinal axis of the rotorcraft
I think this describes x2 exactly. However, a bit back in this thread we came up with:
Originally Posted by NickLappos
IFMU,
Here are the definitions:
A compound helo has auxiliary propulsion - a jet or prop. It is said that the world record Lynx used about 7% aux thrust from its engines (a small enough percentage to allow it to be classed as a true helicopter).
A winged helicopter has a wing that develops lift.
A winged compound has both.
So if we believe Nick, it is a compound helicopter. It seems clear to me that the X2 can never take away G-LYNX's record, as it is a different class of machine. None of that is necessarily bad.
-- IFMU