Spline claims that:
Loads, radius, airfoil thickness, blade stiffness, and tip deflection all change so that the blades are strained the same.
Exactly how do you propose you achieve stiffness for the same strain within a linearly scaled aero envelope without increasing structure and in turn weight?
An increase in size by a factor of 2 would require a
quadratic increase in stiffness (EI), as your material modulus is invariant in our example case. Greater stiffness with the same materials requires more material, and results in larger weight and therefore larger loads. This is a snowball effect. Mach scaling a rotor radius 200% is a cubic function for mass, square function for loads.
A blanket statement like:
blade tuning to similar fan plots is acheiveable across wide ranges of rotor diameters
in light of the immense structural changes required by scaling up is dubious. I've seen it time and time again on trade studies of rigid rotors - from coax to tiltrotor.
In any case, the added mass has a cascading effect on mast moments and rotor hub structure also increasing the sizing in the non-blade rotating system as well.
If rigid rotors in general scaled as easily as you suggest here, then existing conventional medium and heavy helicopters would already implement that rotor system as it offers significantly better control power and a far less complex and costly rotor head assembly. Sikorsky also would not have candidly admitted that
X2 technology does not scale beyond the medium class in 2011
Edit: The link is now dead, I wonder why?
Alt reference