>>1318405The S-97 can most likely operate in a near-autorotation state. At very high forward velocities, the fuselage (and hence the rotor system) is pitched nose up about 3-5 degrees, drastically reducing the power consumed by the rotor system and allowing more power to go to the propulsor. The rotor power required doesn't drop to zero, like a true autogyro, but is very close. Maybe around 10-20 HP? See attached image.
Note: this is all speculation based on reading about the X2TD, although I assume the S97 works basically the same way.
