Originally Posted by
paco
...Bell once used blades on a Bell 206 that were double the normal weight and they ended up with a gamma of 180°! In fact, the blades had so much energy that there was also no H/V curve.
paco, you motivated me to search the internet for more about these tests and the test report is publicly available at:
https://apps.dtic.mil/sti/tr/pdf/ADA071648.pdf
The report titled "Flight Test Evaluation of the High Inertia Rotor System" was produced by Bell Helicopter Textron in June 1979. The tests used a modified prototype OH-58A and evaluated three different rotor inertias with the lowest being similar to the rotors of the standard OH-58A and the highest being more than double that inertia. Blades were not necessarily double the standard weight, rather the high inertia was achieved by adding more tip masses to the modified rotor system. Page 40 shows the H-V curve for the standard and three different inertias. No limit curve for the highest inertia as you said. Page 96 reports a case of apparent entry into VRS for one of the test points with the helicopter contacting the ground but then becoming airborne again due to the available inertia! Page 97 discusses the more sluggish response of the higher inertia rotor, but addressed by incorporating a "control quickener".