Risk mitigation is still a part of things I would think.
Agreed.
However, a couple of years ago the Coaxial-ABC was Sikorsky's proposal for the Joint Heavy Lift requirement. Apparently it was rejected. Then Sikorsky changed horses and started to promote the Variable Diameter Rotor system.
With cynicism, I suspect that the X2 craft, its
Design Patents, and its promotion, collectively suggest that the craft may have originated in the Marketing department and not the Engineering department.
My question and that of others has been; Assuming that the aerodynamic and aeromechanical features of the Coaxial-ABC configuration are potentially viable, why wasn't there a low-budget and low-profile continuation of research and development on the Advancing Blade Concepts during the past 30 years, since the XH-59A ABC.
Dave