Many flight vehicles use controllable flight surfaces, such as canards or tails, to achieve guidance acceleration commands as well as to control various aspects of the vehicle's flight including roll angle. At higher angles-of-attack, some canard-controlled flight vehicles may experience control instability, such as a roll-control reversal. A roll-control reversal occurs when the airflow over the canards interacts with the tail fins to cause the flight-vehicle to roll in a direction opposite that achieved at lower angles-of-attack.
Static acceleration limits have been conventionally used to help ensure flight-vehicle stability by statically limiting the angle-of-attack of a flight vehicle. One problem with these static acceleration limits is that these limits are conservative to account for the uncertainty of the angle-of-attack at which roll-control reversals occur. As a result, the acceleration capability of a flight vehicle is reduced, resulting in lower performance levels (e.g., lower maneuverability and range).
Thus, what are needed are improved flight-control systems that prevent instability, such as roll-control reversal, in flight vehicles. What are also needed are flight-control systems that avoid roll-control reversals but do not overly restrict the acceleration capability of the flight vehicle. What are also needed are flight-control systems that help avoid roll-control reversal by adapting in real-time to measures of flight performance to allow higher acceleration limits.