Aircraft Stability Analysis Including Unsteady Aerodynamic Effects

1205 ConclusionsPhysical models may have a higher computational cost than the functional ones, but theirderivation follows a rationale that is dictated by the physical laws that, like a roadmap,lead to a logical result. Otherwise, there are theoretically lots of functional modelscapable of representing a certain physical phenomenon and this research has shown thatthe job of figuring out the one that fits can be daunting. Here, the job of finding onedynamic functional model with a state-space formulation that represents wing rock wasmade a little bit less daunting by following the guidance of physical properties of theflow observed in previous work. As a result, the second proposed and investigated modelwas shown to be capable of representing wing rock even when used with sparseexperimental data. We believe that, with the help of a better set of experimental data,obtained from the wind tunnel or from computational fluid dynamic programs, far betterresults can be reached.It is opportune to remember that the slender delta wing configuration simulated here wassplit into just two panels, and that the simulation is carried out for just one degree offreedom. According to the results shown in Section 4.2, the application of the proposedformulation to this kind of problem gives as a result a dynamic system containing twoequations of motion plus six internal state equations for the unsteady aerodynamic model,making a total of eight first-order differential equations to be simultaneously integrated.Notice that, if we had a conventional airplane configuration split into six panels to besimulated in a six degree of freedom motion, the total number of state equations would bethirty.In system identification, an appropriate model should have the following characteristics:(a) to reproduce well enough the plant behavior in the range where the data used toidentify parameters were gathered;(b) the parameter identification should be easy;(c) have good ability for generalization.