Helicopter rotor dynamic inflow modeling for maneuvering flight

Off-axis coupling of a helicopter exhibits the opposite sign in flight test s as compared to simulations. It has been shown that this effect may be att ributable to the bending of the wake during a pitching maneuver, which intr oduces a fore-to-aft gradient in induced How that can reverse the predicted sign of roll coupling. It has been shown that this result can also be obta ined with momentum and vortex theory. In the present work, a generalized mo del for wake curvature in hover is developed using the exact relation deriv ed from vortex tube theory. This model is coupled with a flap model to inve stigate the influence on dynamic coupling.