## 2 Model and Methods  
The analysis model used is a standard type commonly employed for dynamic analysis. The structural components are represented using a finite element (FE) stick model, the aerodynamics is handled by a doublet-lattice method (DLM), and non-structural masses (fuel, payload, engines, etc.) are represented by concentrated masses. The model is shown in Figure 1.  
Regarding the active controller, the control surfaces already modeled in the aeroelastic model include the ailerons, which move symmetrically, and the elevator. A minor modification to the model was necessary to account for the folding wing tip. Specifically, the outboard section of the wing was modified to incorporate the hinge kinematics. At the location of the hinge, two coincident nodes were introduced, with the two parts connected through a set of multiple point constraints (MPCs), except for the rotational degree of freedom related to the hinge. Additionally, a dedicated coordinate system was added to replicate the flare angle identified in the study conducted by the University of Bristol [36]. Figure 2 presents a schematic of the model of the flared FWT. Although the model is written in Nastran format, the analysis was performed using NeoCASS. NeoCASS includes a feature that identifies the generalized aerodynamic forces (GAFs) using matrix fraction approximation (MFA) [38], which enables the aero-servo-elastic problem to be formulated in the time domain. The aeroelastic problem is expressed in a state-space model, as shown in Equation (1). The subscript \(x_{ae}\), representing the aeroelastic state, indicates that the state vector includes both structural states (modal velocity and displacement) and the aerodynamic states used to determine the unsteady GAFs. The system inputs are the control surface deflections \(u\) and the gust \(v_{g}\). \(\mathbf{A}\) is the state or system matrix, \(\mathbf{B_{\bullet}}\) are the inputs matrices, \(\mathbf{C}\) is the output matrix and \(\mathbf{D_{\bullet}}\) are the feed-through matrices. A second-order low-pass filter with a cut-off frequency of 15 Hz was applied to mimic the behavior of real actuators. \[ \begin{cases}\dot{\mathbf{x}}_{\mathbf{ae}}&=\mathbf{A}\mathbf{x}_{\mathbf{ae }}+\mathbf{B}_{\mathbf{u}}\mathbf{u}+\mathbf{B}_{\mathbf{g}}\mathbf{v}_{ \mathbf{g}}\\ \mathbf{y}&=\mathbf{C}\mathbf{x}_{\mathbf{ae}}+\mathbf{D}_{\mathbf{u}}\mathbf{ u}+\mathbf{D}_{\mathbf{g}}\mathbf{v}_{\mathbf{g}}\end{cases}  \tag{1}\]  
Several flight and mass conditions were analyzed in this work, resulting in the development of multiple state-space models that account for varying aerodynamic conditions (Mach number), as well as different payload and fuel distributions. A constant equivalent air speed (EAS) of \(V_{EAS}=150\) m/s was considered across six different altitudes, ranging from 0 m to 10,000 m in 2000 m increments. The four mass configurations are detailed in Table 1.  
Figure 1: The aeroelastic model of the considered aircraft. Figure 2: The plan-form view of the wing with the modified kinematics to model the flared FWT. For each flight condition and mass configuration, 20 gusts are considered, with both positive and negative amplitudes. Their 1-cosine gust gradients are evenly spaced between H = 9 m and H = 107 m, in accordance with CS25 regulations [39]. The gust amplitude is calculated using Equation (2), with an alleviation factor of \(F_{g}=1\). Following the CS 25.341 Gust and Turbulence Loads nomenclature, \(U_{ds}\) is the design gust velocity in the equivalent airspeed, \(U_{ref}\) is the reference gust velocity in the equivalent airspeed and \(\rho_{\bullet}\) is the air density at sea level (0) and at a prescribed altitude (z).