# Design of a Human Muscle-Powered Flying Machine
## 6 Structural Development of the Human-Powered Aircraft
### Comparison of Results with Requirements  
The aircraft design scheme proposed by [PERSON] (Figure 3) consists of ten stages focused on analyzing and optimizing the structure [45]. The paper presented a preliminarily optimized design, where continuous adjustments were made at each individual stage. After determining the drag in the earlier stages of the design process, it is necessary to select the thrust force required for flight. An average thrust force of 25 N was adopted based on prior aerodynamic calculations and flight requirements. The propeller blade shape was designed using the JavaProp program. In the first stage, the propeller profile and angle of attack were selected. The Clark Y profile, available in the JavaProp program, was chosen as it meets the design requirements (Figure 10(a)). Next, in the Design tab, the basic parameters of the propeller were determined as follows: the number of blades were 2, the rotations per minute are 185 rpm, the outer diameter is 2.8 m, the inner diameter is 0.1 m, the flight speed is 9.5 m/s, and the thrust generated 25 N (Figure 10(b)). The desired parameters are calculated by the program after entering the base parameters (Figure 10(c)). From these, it can be observed that the power required to drive the propeller should be \(P_{P}=267.12\) W. This is consistent with the design assumptions made at the outset. The propeller efficiency is 88.9%. The final stage involved transferring the blade geometry (Figure 11(a)) to the 3 DEperience program to model the entire propeller. The file was saved in the.IGS format, which can be opened as a surface. Based on the blade geometry, the propeller project was created. The Thick Surface function was utilized to generate a wing shell from the surface. Using the Shaft function, a shaft of complete propeller was created (Figure 11(b)). The final step in determining the power required to keep the structure in the air was to establish losses in the belt drive. For this purpose, the total belt tension and forces on the shaft needed to be determined. The belt used has low initial tension and can transmit large forces, so formulas used for calculating chain drive parameters were applied. For the project, an initial tension of 150 N, a pitch of the belt of 11 mm, a speed of the driving wheel of 90 RPM, and the power transmitted by the drive of 0.3 kW were assumed. The linear velocity for two belts was determined using formula \(v=(pZ_{1}n_{1})/(60\cdot 10^{3})\). Calculated results were \(v_{1}=0.64\) m/s, and for the second one, \(v_{2}=1.15\) m/s. Following the total static tension was calculated using formula \(F_{ST}=(1000P)/v\). For the first belt, it was \(F_{ST1}=468.8\) N, and for the second one, it was \(F_{ST1}=260.9\) N. In the next step, the losses in the belts were determined, amounting to \(L_{SP1}=3\) W for the first belt and \(L_{SP2}=2.5\) W for the second belt. The final step was to calculate the forces on the shaft \(F_{SH}=F_{ST}\cdot 1.2\). For the first belt, this amounted to \(F_{SH1}=562.6\) N, and for the second belt, \(F_{SH2}=313.1\) N.  
Figure 16: Steps in aerodynamic analysis process. All models of bearingsings used in the design were obtained from the SKF manufacturer. This allowed for the use of a special bearing selection and parameter SKF online tool [56]. In the first step, the positions of the bearings and gears were determined, using the previously created model and based on models created by the manufacturer (Figure 17c). Knowing the losses and the power required to drive the propeller, the total power required to keep the structure in the air was calculated. To calculate the total power \(P_{T}\) required to keep the aircraft in the air, the following equation was used:  
\[P_{T}=P_{P}+P_{SL1}+P_{SL2}+P_{SL3}+P_{SL4}+P_{SL5}+P_{SL6}+4P_{P}. \tag{8}\]  
The term \(P_{P}\) refers to the power required to drive the propeller, while \(P_{SL}\) refers to various system losses. The term \(4P_{P}\) represents additional power considerations based on fourfold thrust requirements.