# Design of a Human Muscle-Powered Flying Machine
## 6 Structural Development of the Human-Powered Aircraft
### Final Evaluation of Results  
All initial assumptions were met during the design stages of the structure, hypothetically making the muscle-powered aircraft (Figure 18) capable of flying at a speed of 9.5 m/s at an altitude greater than 3 m. According to the assumption, with a total mass of 96.4 kg, the lift force needed to sustain the aircraft in the air should be around 945 N. Analyses conducted in the Fluid Scenario Creations module of the 3 DE experience program showed that the designed structure is capable of reaching an altitude of 6.4 m, where the lift force will be 963.7 N, and the drag force will be 24.7 N. To generate the thrust necessary to counteract the drag force, a power of 269.5 W is needed. This value is significantly lower than the value assumed in the initial assumptions (350 W). According to the graph of human output power over time (Figure 2), this value of power (269.5 W) allows an average, healthy man weighing 70 kg to sustain a flight of approximately 20 min. Figure 17: (**a**) Designed propeller wing (**b**) complete propeller (**c**) location of bearings and gears. Table 1 compares the proposed design solution with selected known solutions from the past. The main design innovation in this paper (Table 1) was the use of a drive belt applied in modern bicycle drive designs, which is characterized by low weight, lower losses in comparison with traditional types of toothed belts and extended service life compared to a chain. Table 2 summarizes the important operating data of selected HPAs. From Table 2, it follows that the mean weight of most past HPAs is 37.9 kg, while the weight of the designed construction is only 26.4 kg. However, during the next stages of this research, when building the prototype and conducting tests, this weight could increase by approximately 15% (around 4 kg). The assumed wingspan of the designed HPA is 1.5 m larger than the mean wingspan of previously successful HPAs. The calculated power required for flight and the propeller RPM are 16 W lower and 24.5 RPM higher, respectively, than the average values. Another important observation is the design flight altitude, which, for previous HPAs, was approximately 6.7 m (though this data were difficult to obtain for many HPAs), while the designed airplane assumes an altitude of 6.4 m. The designed flight speed of 9.5 m/s of the proposed HPA is higher than that of most earlier typical \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Name of HPA** & **Propeller Location** & **Drive Transmission** & **Pilot Position** \\ \hline SUHPA Lazarus & Pusher propeller & Chain & Upright \\ \hline Gossammer Albatross & Pusher propeller & Chain & Upright \\ \hline Velair 89 & Pusher propeller & Chain + shaft & Recumbent \\ \hline Light Eagle & Tractor propeller & Chain & Recumbent \\ \hline DaSH v5 (or PA) & Tractor propeller & Chain & Recumbent \\ \hline Daedelus & Tractor propeller & Shaft & Recumbent \\ \hline Airglow & Pusher propeller & Shaft + chain & Recumbent \\ \hline Aerocycle 3 & Pusher propeller & Shaft + chain & Recumbent \\ \hline Gossamer Condor & Pusher propeller & Chain & Recumbent \\ \hline Bionic Bat & Pusher propeller & Chain & Recumbent \\ \hline Betterfly & Tractor propeller & Chain & Recumbent \\ \hline Abhilasha & Tractor propeller & Chain & Upright \\ \hline Monarch B & Tractor propeller & Chain & Recumbent \\ \hline Proposed design & Pusher propeller & Drive belt & Recumbent \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Main differences in HPA design. Figure 18: The final model created in the 3 DExperience program. constructions (see Table 2), as well as those competing in the Japan Birdman Rally, which range from 6 to 7.5 m/s [13]. The insights gained from HPA design techniques can potentially advance the development of unmanned high-altitude airplanes, particularly in terms of lightweight structures, low Reynolds number aerodynamics, and efficient propeller design needed for atmospheric research applications.