Flight envelope limit detection and avoidance for rotorcraft

Tactile cueing systems have been shown to be effective for protecting against envelope violations and providing carefree handling qualities. Cueing systems require algorithms to detect approaching limits before they are exceeded. In a previous study, dynamic trim estimation using neural networks was shown to be an effective method for detecting limits that are reached in quasi-steady flight, and the method was demonstrated in real-time piloted simulation. The method has been extended to include adaptation to variations in weight and balance parameters or modeling errors. The adaptive limit avoidance system is applied to provide angle of attack and load factor protection on the XV-15, and the system is demonstrated in non-real-time simulation using a pilot model. A modified algorithm is developed to provide envelope cueing for parameters that impinge on limits in the transient response and is applied to limit longitudinal flapping on the XV-15.