Long flight durations are highly desirable to expand mission capabilities for unmanned air systems and autonomous applications in particular. Flapping wing aerial vehicles are unmanned air system platforms offering several performance advantages over fixed wing and rotorcraft platforms, but are unable to reach comparable flight times when powered by batteries. One solution to this problem has been to integrate energy harvesting technologies in components, such as wings. To this end, a framework for designing flapping wing aerial vehicle using multifunctional wings using solar cells is described. This framework consists of: (1) modeling solar energy harvesting while flying, (2) determining the number of solar cells that meet flight power requirements, and (3) determining appropriate locations to accommodate the desired number of solar cells. A system model for flapping flight was also developed to predict payload capacity for carrying batteries to provide energy only for power spikes and to enable time-to-land safely in an area where batteries can recharge when the sun sets. The design framework was applied to a case study using flexible high-efficiency (>24%) solar cells on a flapping wing aerial vehicle platform, known as Robo Raven IIIv5, with the caveat that a powertrain with 81% efficiency is used in place of the current servos. A key finding was the fraction of solar flux incident on the wings during flapping was 0.63 at the lowest solar altitude. Using a 1.25 safety factor, the lowest value for the purposes of design will be 0.51. Wind tunnel measurements and aerodynamic modeling of the platform determined integrating solar cells in the wings resulted in a loss of thrust and greater drag, but the resulting payload capacity was unaffected because of a higher lift coefficient. A time-to-land of 2500 s was predicted, and the flight capability of the platform was validated in a netted test facility.

中文翻译：

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一种利用太阳能电池实现扑翼飞行器多功能机翼的设计框架

长飞行持续时间非常适合扩展无人机系统和自主应用的任务能力。扑翼飞行器是无人空中系统平台，与固定翼和旋翼机平台相比具有多项性能优势，但在由电池供电时无法达到可比的飞行时间。这个问题的一个解决方案是将能量收集技术集成到部件中，例如机翼。为此，描述了使用太阳能电池的多功能机翼设计扑翼飞行器的框架。该框架包括：(1) 在飞行时对太阳能收集进行建模，(2) 确定满足飞行功率要求的太阳能电池数量，以及 (3) 确定合适的位置以容纳所需数量的太阳能电池。还开发了扑翼飞行系统模型，以预测携带电池的有效载荷容量，以便仅为功率峰值提供能量，并确保在太阳落山时电池可以充电的区域安全着陆。该设计框架应用于在名为 Robo Raven IIIv5 的扑翼飞行器平台上使用灵活高效 (>24%) 太阳能电池的案例研究，但需要注意的是，使用效率为 81% 的动力总成代替当前的伺服器。一个关键的发现是，在最低太阳高度，拍动期间入射到机翼上的太阳通量分数为 0.63。使用 1.25 的安全系数，出于设计目的的最低值为 0.51。该平台的风洞测量和空气动力学建模确定，在机翼中集成太阳能电池会导致推力损失和更大阻力，但由于升力系数较高，因此产生的有效载荷能力不受影响。预计着陆时间为 2500 秒，平台的飞行能力在网状测试设施中得到验证。