# Effect of Electric Ducted Fans Structural Arrangement on Their Performance Characteristics
## 3 Results  
The differences in the dependence of thrust on electrical power for all tested EDFs are shown in Figure 5. A comparison of the original EDFs and the printed prototypes with fan diameters of 50 mm and 64 mm is then shown in Figure 5A. The figure shows that the 3D printed prototypes have worse energy characteristics compared to the purchased originals. To achieve a thrust value of 0.2 kgf (approx. 1.96 N), the 50 mm 3D printed prototype needs 37 W more power than the purchased EDF and the 64 mm prototype needs 61 W more power than the purchased EDF. Additionally, the produced prototypes achieved a lower maximum thrust value. The original EDF achieved thrust values of around 0.7 kgf (approx. 6.87 N) and the produced prototypes achieved around 0.3 kgf (approx. 2.94 N). In Figure 5B, the difference for the tested 50 mm 3D printed prototypes is shown. The increasing outlet diameter (EDF\({}_{50/1.1}\)) reduced power consumption to achieve the same thrust, when 123 W was needed to achieve a thrust of 0.2 kgf (aprox. 1.96 N). On the contrary, narrowing the channel (EDF\({}_{50/0.8}\)) toward the output increased the power consumption and a thrust of 0.2 kgf (approx. 1.96 N) was achieved with a consumption of 198 W, which is the highest consumption of all tested 50 mm prototypes. In a constant reference cross-section (EDF\({}_{50/1}\)), a thrust of 0.2 kgf (approx. 1.96 N) was achieved with a power input of 135 W.  
The difference in dependencies for 3D printed prototypes with a diameter of 64 mm with 12-blade fan is shown in Figure 5C. The results show that the energy consumption decreases with the widening outlet and the consumption increases with the narrowing outlet. With an expanding output (EDF\({}_{64/1.1}\)), the power consumption was 152 W to produce 0.2 kgf (approx. 1.96 N) thrust, which is even an increase of 4 W compared to the constant cross-section. However, with a further increase of \(a_{w}\) value, the consumption already decreases as EDF\({}_{64/1.3}\) consumption of 140 W was measured. Such a value is already close to the difference for the modification with 50 mm diameter (EDF\({}_{50/1.1}\)). The last modification tested (EDF\({}_{64/1.7}\)) achieved the lowest consumption of all prototypes of 116 W. In the 64 mm specification, the narrowing channel (EDF\({}_{64/0.8}\)) was also tested and reached the highest consumption of all prototypes, approximately 220 W for a thrust of 0.2 kgf (approx. 1.96 N). The PCA confirms that the different EDFs show unique characteristics as the 95% confidence ellipses which are constructed around separate clusters do not overlap (see Figure 5D). Furthermore, it is apparent that the characteristics of each EDF obtained during repeated measurements are similar, since the clusters consisting of respective scores are rather small, as are the areas of the ellipses. Comparisons of the dependence of thrust on fan RPM for identical EDFs shown in previous figures are presented in Figure 6. In Figure 6A, a comparison of the original  
Figure 5: Comparison of power characteristics for (**A**) 3D printed vs original EDF, (**B**) 50 mm 3D printed prototypes, (**C**) 64 mm 3D printed prototypes, (**D**) biplot showing loadings for first two principal components (PC1 and PC2), and scores with 95% confidence ellipses. Note that top-right axes (blue) correspond to the loadings and bottom-left axes (black) correspond to the scores. purchased EDF and 3D printed prototypes with fan diameters of 50 mm and 64 mm is shown. Printed prototypes have a worse dependence and generally need to reach a higher RPM to achieve the same thrust value. The results also show that as the diameter of the fan increases, the necessary revolutions to achieve a specific thrust value decrease. For the 50 mm 3D printed prototype, it is necessary to reach \(2.63\times 10^{4}\) RPM to achieve a thrust of 0.2 kgf (approx. 1.96 N), while for the 64 mm prototype, it is necessary to achieve only \(1.6\times 10^{4}\) RPM. In Figure 6B, the dependence for 50 mm prototypes is shown.