## 4 Results and Discussion
### Estimation Accuracy--Side Gusts  
The graphs in this section depict ideal side gusts measurement (obtained from the simulator's weather section module) with the low-frequency signal V\({}_{\text{g-lo}}\) (derived from speed and drift angle measurements) and the complete estimation V\({}_{\text{g-est}}\) (a fusion of low-frequency signal V\({}_{\text{g-lo}}\) and high frequency signal V\({}_{\text{g-hi}}\)--based on side acceleration measurement, using a CF). These comparisons were made for three considered phases of flight. The first analyzed flight phase was descent (Figures 38-40). Three data ranges were chosen for graphical presentation: the entire descent part of simulation (50-320 s), a series of selected gusts (120-195 s), and a single gust (146-168 s). The graphs illustrate the influence of varying the complementary filter time constant \(T_{\text{cv}}\) on the estimation results. Four \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**F. Phase**} & \multirow{2}{*}{**Rising Gust Speed**} & \multicolumn{3}{c}{**Weakening Gust Speed**} & \multicolumn{2}{c}{**Average Values**} \\  & & \multicolumn{3}{c}{**Speed**} & \multicolumn{2}{c}{**Average Values**} \\ \hline \(\mathbf{T_{\text{cu}}}\) & **Difference** & **Delay** & **Difference** & **Delay** & **Difference** & **Delay** \\ \hline D/T\({}_{\text{cu}}\) = 0.5 s & \(-\)0.64 m/s & 0.39 s & 0.37 m/s & 0.95 s & \(-\)0.135 m/s & 0.67 s \\ D/T\({}_{\text{cu}}\) = 0.8 s & **0.02 m/s** & 0.39 s & \(-\)**0.04 m/s** & 0.95 s & \(-\)**0.01 m/s** & **0.67 s** \\ D/T\({}_{\text{cu}}\) = 1.0 s & 0.34 m/s & 0.39 s & \(-\)0.20 m/s & 0.95 s & 0.07 m/s & 0.67 s \\ D/T\({}_{\text{cu}}\) = 1.5 s & 0.79 m/s & 0.39 s & \(-\)0.34 m/s & 1.05 s & 0.225 m/s & 0.72 s \\ \hline L/T\({}_{\text{cu}}\) = 0.5 s & \(-\)**0.20 m/s** & 0.50 s & 0.58 m/s & 0.30 s & **0.19 m/s** & **0.40 s** \\ L/T\({}_{\text{cu}}\) = 0.8 s & 0.46 m/s & 0.50 s & \(-\)**0.03 m/s** & 0.30 s & 0.215 m/s & 0.40 s \\ L/T\({}_{\text{cu}}\) = 1.0 s & 0.84 m/s & 0.50 s & \(-\)0.39 m/s & 0.32 s & 0.225 m/s & 0.41 s \\ L/T\({}_{\text{cu}}\) = 1.5 s & 1.61 m/s & 0.50 s & \(-\)1.20 m/s & 0.32 s & 0.205 m/s & 0.42 s \\ \hline C/T\({}_{\text{cu}}\) = 0.5 s & \(-\)3.94 m/s & 0.71 s & \(-\)**0.05 m/s** & 0.25 s & \(-\)1.995 m/s & 0.48 s \\ C/T\({}_{\text{cu}}\) = 0.8 s & \(-\)3.02 m/s & 0.71 s & \(-\)0.46 m/s & 0.26 s & \(-\)1.74 m/s & 0.485 s \\ C/T\({}_{\text{cu}}\) = 1.0 s & \(-\)2.47 m/s & 0.71 s & \(-\)0.78 m/s & 0.26 s & \(-\)1.625 m/s & 0.485 s \\ C/T\({}_{\text{cu}}\) = 1.5 s & \(-\)**1.33 m/s** & 0.71 s & \(-\)1.60 m/s & 0.26 s & \(-\)**1.465 m/s** & **0.485 s** \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Computational comparison of the selected peak gusts values for complete headwind estimation with reference measurements for different time constants and flight phases (D—descent, L—level flight, C—climb). Figure 37: Comparison of the gust value with the estimation results—climb crossing a gust area; single selected gust (complementary filter, (**A**) T\({}_{\text{cu}}\) = 0.5 s, (**B**) T\({}_{\text{cu}}\) = 0.8 s, (**C**) T\({}_{\text{cu}}\) = 1.0 s, (**D**) T\({}_{\text{cu}}\) = 1.5 s). selected time constant values (0.5 s, 0.8 s, 1 s, 1.5 s) were used for graphical comparison of the estimation against the recorded gusts. Based on the charts, it can be concluded that the estimation results best matched the reference measurements for time constants of 0.5 s and 0.8 s. The assessment also confirmed that increasing the time constant from 0.8 s to 1.0 and 1.5 s led to an underestimation of the maximum gust values--mostly opposite to the trend observed in the head-on gusts estimation. Figure 39: Comparison of the gust value with the estimation results—descent crossing a gust area; series of selected gusts (complementary filter, (**A**) T\({}_{\rm cv}\) = 0.5 s, (**B**) T\({}_{\rm cv}\) = 0.8 s, (**C**) T\({}_{\rm cv}\) = 1.0 s, (**D**) T\({}_{\rm cv}\) = 1.5 s).