Maneuver Load Analysis of Overdetermined Trim Systems

A new method for computational fluid dynamics-based maneuver trim optimization is presented, in which the aircraft is trimmed by using the angle-of-attack, tail deflection, and wing control surfaces. The method belongs to the category of closely coupled aeroelastic analyses, in which the flow analysis, elastic deformations, and trim optimization computations are embedded within the computational fluid dynamics code, and performed within a single run. The method is tested on a maneuvering fighterlike aircraft model in a 1-g level flight, at Mach 0.5, sea level, and a 5-g pull-up maneuver, at Mach 0.8, sea level. The trim algorithm is found to be robust, and the closely coupled approach is computationally efficient. The newly proposed methodology provides a tool for computing loads on a maneuvering realistic aircraft in both traditional maneuver trim, and when wing control surfaces are used. It can be used to compute nonlinear maneuver loads, in the transonic flight regime, for structural design, and to gain insight on control laws that can be applied to reduce maneuver loads on existing aircrafts.