Vertical takeoff and landing (VTOL) capability has extended the application of unmanned aerial vehicle (UAV) significantly. In this paper, simulation modeling and flight test were employed to investigate the hovering stability of a tail-sitter UAV named Egretta. The hovering stability simulation model was developed based on a simplified rigid body flight dynamic and the time-averaged propeller slipstream flow distribution. Meanwhile, a testing vehicle with PID controllers was built and tested to verify the hovering stability model. It was found that the Egretta UAV can achieve stable hovering in the roll, pitch, and yaw directions. The simulation model has demonstrated accuracy in predicting the hovering stability and dynamic responses with large perturbations in both trend and magnitude. Moreover, the simulation model can be extended to analyze the hovering stability of tail-sitter UAVs with different sizes. The simulation model will be very useful for initial stability sizing and PID optimization investigation.

中文翻译：

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Egretta Tail-Sitter 垂直起降无人机的悬停稳定性

垂直起降（VTOL）能力大大扩展了无人机（UAV）的应用。本文采用仿真建模和飞行试验研究了名为 Egretta 的尾翼无人机悬停稳定性。基于简化的刚体飞行动力学和时间平均的螺旋桨滑流分布，建立了悬停稳定性仿真模型。同时，搭建了带有PID控制器的测试车并进行了测试，以验证悬停稳定性模型。研究发现，Egretta 无人机可以实现横滚、俯仰和偏航方向的稳定悬停。仿真模型在预测悬停稳定性和动态响应方面表现出准确性，并在趋势和幅度上都有较大的扰动。而且，该仿真模型可扩展用于分析不同尺寸的尾翼无人机悬停稳定性。该仿真模型对于初始稳定性确定和 PID 优化研究非常有用。