## 4 Simulation Results and Discussion
### Simulation of Flight Cruising in a Real Wind Field
#### 4.2.2 Comparison of Energy Generation  
Figure 14a,b illustrate the electricity generation of the PV array for the two-day wind-resistance strategy. The red, blue, yellow, and green lines represent the RC, SP, VTCT, and HTCT, respectively. With this strategy, the airship exhibits minimal yaw angle variation, resulting in a stable output power curve for the array. The airship experiences minimal variation in yaw angle, and the output power of the PV array is relatively stable. On 21 December, the PV array began generating electricity at 7:00, reaching maximum power at approximately 13:00, with values of 186.5 kW, 171.2 kW, 177.8 kW, and 135.2 kW for the RC, SP, VTCT, and HTCT, respectively. Electricity generation ceased at 17:50, with the RC maintaining the highest output power throughout the day. Notably, the RC configuration showed significant improvement during the time periods of 9:00 to 11:00 and 14:00 to 16:00. This can be attributed to lower solar altitude and the airship's curvature, resulting in significant differences in the irradiance distribution along the axial and radial. Due to rapid changes in pitch angles, all configurations experienced fluctuations at 14:20 and 16:50. Figure 14b exhibits the same pattern. It is worth noting that on both days of the simulation, the HTCT configuration consistently exhibited the lowest output power. Configurations with row modules arranged radially on the airship are inferior and unsuitable for airship PV array deployment. The PV array exhibits more pronounced fluctuations in output power during the circular cruising strategy compared to wind resistance, as depicted in Figure 14c,d. On 23 December, with periodic changes in the roll angle, the output curves of the SP and VTCT configurations show significant power dips, occurring 7 times and aligning with the airship's cruising cycle. Conversely, the HTCT configuration exhibits opposite fluctuations. The RC configuration maintains a stable power output, with only a minor power fluctuation occurring at 13:00, and the output power remains at its maximum throughout the entire irradiation process. Additionally, the RC configuration performs even better on 24 December, with no power fluctuations observed throughout the full irradiation period, despite other configurations still experiencing significant cyclic fluctuations, while maintaining the optimal output power consistently. For circular cruising, the RC configuration not only enhances the output power of the PV array but also improves the stability of the PV array's output. Furthermore, it is evident that the yaw angle has a greater impact on the output power than the roll angle during the cruising mode. Figure 15 presents the daily energy generation of the four configurations. The RC configuration consistently demonstrates the highest performance level throughout the four-day flight period. The total energy output amounts to 10,220 kWh, surpassing the VTCT configuration by 10.6%, the SP configuration by 13.8%, and the HTCT configuration by 26.6%. This significant improvement enhances the power supply capability of the PV array, thus confirming the superiority of the proposed RC configuration. The introduced RC configuration offers a promising solution to mitigate the energy shortage issue during  
Figure 13: Yaw angle and Pitch angle from 21 December to 25 December. verification, it has been demonstrated that the proposed RC configuration effectively improves the output power of the airship photovoltaic array compared to the traditional TCT and SP configurations. Additionally, the issue of local maximum power points caused by variations in irradiance distribution are eliminated. The main conclusions can be summarized as follows:  
1. The irradiance of the PV array exhibits a radial and circumferential gradient along the stratospheric airship. This gradient distribution varies systematically with the pitch and yaw angles. The non-uniformity in the irradiance distribution across the array leads to mismatch losses and significantly impacts the power output of the PV array.