Helicopter Longitudinal Stability in Forward Flight With Control Feedback and Fuselage Aerodynamics

An evaluation of forward flight longitudinal stability is made for a small single-rotor helicopter with various types of control feedback. The effects of fuselage pitching moment characteristics on stability are also evaluated. The evaluations are based on solutions from an electronic analog computer. Control displacement due to feedback is proportional to changes in each of the following variables (with zero time lag), considered separately: Pitch attitude, Pitching velocity, Normal acceleration, and Angle of attack.