###### Abstract
There are several types of electric machines, such as induction machines, switched reluctance motors, permanent magnet machines, and superconducting machines. There are advantages and disadvantages for each type of machine. To explain briefly, \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Class** & **Category** & **Mass [kg]** & **Range [km]** & **Altitude [m]** \\ \hline Class I & Micro & \textless{}5 & \textless{}5 & \textless{}100 \\  & Mini & \textless{}15 & \textless{}25 & \textless{}1000 \\  & Small & \textgreater{}15 & \textless{}50 & \textless{}1500 \\ Class II & Tactical & 150–600 & \textless{}200 & \textless{}5500 \\ Class III & MALE & \textgreater{}600 & Unlimited & \textless{}13,000 \\  & HALE & \textgreater{}600 & Unlimited & \textless{}20,000 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: UAV classification. Figure 1: Schematic representation of an electric propulsion system. induction machines have a low efficiency when compared with others, as well as a low break torque limit and power factor. Switched reluctance motors have a low cost, are easy to maintain, and have independent torque-speed control, but they also have a high torque pulse and complex control circuits and are noisy during operation. Superconducting machines have a high efficiency, a high power density, and a small size, but they have not yet been practically realized, and heat issues are very critical because of their inherent structure. Permanent magnet machines have a high power density and efficiency and simple control circuits and are easy to maintain. Permanent magnet synchronous machines and brushless DC machines are often preferred to electric propulsion systems. However, permanent magnet synchronous machines often work at high speeds and need additional components such as gearboxes to implement them on board, in addition to their high power density and low technical risk [31, 32]. A brushless DC (BLDC) motor was chosen for this work because of its easy and precise control of speed, reliability, low cost, easy maintenance, high torque-weight ratio, high efficiency, and low-noise operation. In the literature, there are several studies on the design and implementation of BLDC motors for fully electric Class I and Class II UAVs [23, 33, 34, 35]. However, electric propulsion systems are hard to implement in Class III UAVs because of endurance concerns. Fully electric Class III UAVs can lose their advantages, which come from their long range and flight hours [10, 36, 37, 38, 39]. However, an electric propulsion system could be selected depending on the mission profile due to its inherent advantages. In this respect, the performance of an electric propulsion system was studied, and possible flight durations with the implementation of a newly designed machine on a selected reference UAV model are demonstrated, which constitutes the originality of this study. In the Methodology section, the BLDC motor design processes, the creation of a UAV model with computer-aided programs, the creation of a battery model, and a mission profile are presented with supporting tables and figures. After the creation of all models, information about the processes of combining separately created models is presented, and after that, the simulation is described. The data obtained for both separate and combined models are presented in the Results section. All gathered results are evaluated in the Conclusion section, in addition to the results of the evaluation.