## 3 Research Environment and Plan of Experiment  
### Flight Simulation Environment and Data Acquisition  
A simulator station (Figure 7) was used to evaluate the potential of estimating gust values using the algorithms described in Section 2. The external components of the simulator and their connection are presented on the block diagram (Figure 8). A professional and certified version of the X-Plane 11 Pro software was utilized, enabling enhanced use of the environment's features for research purposes. The weather configuration tool within X-Plane allowed for the generation of wind layers from selected directions. It was possible to define both a constant wind speed and the intensity of gusts generated by the simulator environment. Experimental simulator flights were conducted using a realistic model of the widely used medium-range narrow-body aircraft the B737-800 (Figure 9). This advanced model accurately reflects the aircraft's dynamic characteristics and operational behavior. A major advantage of the selected software is its ability to record all flight parameters required by the estimation methods under consideration. Table 1 presents a comprehensive overview of the recorded flight parameters, encompassing all potentially accessible physical data sources.  
The developed estimation algorithms required the recording of both weather parameters and data from various on-board aircraft's systems, including the: ADIRU, GPS, FCC (Flight Control Computer). More advanced data were not accessible via X-Plane's built-in user interface and instead required referencing X-Plane internal data structures (Datarefs). To accomplish this, the X-Plane Communication Toolbox (XPC) [41] was used to record all flight parameters. XPC was initialized and configured in the Matlab/Simulink environment. This setup enabled the recording and retrieval of internal variables using the UDP protocol (Figure 8).  
Figure 7: Stationary simulator stand with cockpit view of a jet airliner—Boeing 737-800.  
The X-Plane 11 Pro software employs a sophisticated nonlinear model to simulate aircraft dynamics [42]. This model utilizes blade element theory, which divide the aircraft into numerous small elements and calculates the aerodynamic forces acting on each element at frequencies ranging from several to dozens of hertz [43,44]. It accounts for complex environmental factors, including various wind phenomena, such as gusts. Wind parameters (direction, speed, and gust intensity) can be configured independently for each atmospheric layer via the instructor's station module (shown on the right in Figure 8). During data recording, the wind output parameters are stored in the OpenGL coordinate system, which is Earth referenced (illustrated by the red arrows in Figure 10). For the purposes of this study, these parameters were converted into the aircraft's body-fixed coordinate system. As a result, the \(\mathrm{U_{g}}\), \(\mathrm{W_{g}}\), and \(\mathrm{V_{g}}\) wind components were determined (represented by blue arrows in Figure 10).  
Figure 8: Block diagram of the simulator station and data acquisition.  
Figure 10: Coordinate systems: OpenGL—related to the Earth (red), fixed to the center of gravity of the aircraft (green), related to the plane (blue).  
Figure 9: External view of a Boeing 737-800 during simulation (X-Plane v11 Pro, B737-800 ZIBO model).  
In the conducted research, the X-Plane 11 Pro simulator provided three categories of data to the Matlab/Simulink environment:  
Indications from flight instruments (cockpit indicators),  
Data from simulated avionics systems (flight model controls and flight model position),  
Real-time gust parameters generated by predefined wind layers (simulation weather).