垂直起降无人机兼具固定翼高效平飞和旋翼垂直起降的特点，能在狭小空间作业，对起飞场地的依赖性低，适用更多的场合，具有更大的价值。小型垂直起降无人机通常采用锂电池、电机和螺旋桨为能源动力系统，飞行过程中锂电池的实际工作电压发生变化，但飞机的总重量不变，因此电动飞机的设计与传统飞机设计方法有所不同。本文首先建立了小型电动无人机动力系统的模型，通过实验数据验证了各部分模型的准确性。并将此模型应用在电动飞机设计中，为飞机航程航时等性能的评估提供了有力的工具。针对现有尾座式垂直起降无人机的不足，提出了一种将四旋翼与固定翼飞机结合起来具有全新布局的垂直起降无人机，为确定无人机的总体参数，研究了飞机起飞重量与外形参数、结构重量、气动参数之间的关系，得到了以航时和起飞重量为优化目标的整机设计优化模型，采用多目标遗传算法确定了设计点，完成了无人机的设计与制作。随后建立了无人机的动力学模型，利用气动估算软件Datcom得到了无人机的气动力和力矩，结合螺旋桨推力模型，得到无人机的非线性仿真模型，并对飞机的纵向稳定性和操纵性进行了分析。基于动力学模型和最优控制理论，研究了转换过程中的能量消耗问题，利用数值方法得到了以锂电池能量消耗为目标函数的最优控制解，给出了所设计的垂直起降无人机能量消耗最小的转换方案。
VTOL UAVs have the characteristics of both fixed-wing and helicopter. They can operate in narrow space. Without the limitation of landing places, they are applicable on more occasions and more valuable.The energy and propulsion system of small electric UAVs usually consists of lithium batteries, electric motors and propellers. The voltage of lithium batteries varies during flight while the total weight of the aircraft remains unchanged. Therefore, the design process of electric aircraft and traditional aircraft is quite different.This paper establishes the model of propulsion system for small electric UAVs and comparison with the experimental data has proved the model to be reliable. Then the propulsion model is applied to range and endurance estimation which provides a useful tool for performance analysis in the electric UAV design.A novel VTOL UAV combining the drones and fixed-wing aircraft is proposed To determine the parameters of the UAV, relationship among weight, configuration parameters, structure and aerodynamic properties are studied and the optimization model is obtained. Based on the multi-objective genetic algorithm, the best design parameters are determined.Afterwards, the dynamic model of the UAV is established. The aerodynamic force and torque are estimated with Datcom. With the propeller thrust model the nonlinear simulation model of the UAV is obtained. and the longitudinal stability and maneuverability are analyzed. Based on the dynamic model and optimal control theory, the energy consumption in the transition from vertical flight to level flight is studied. Taking battery energy consumption as the objective function, the optimal control solution for the transition flight is found with numerical method and the minimum energy consumption transition plan for the UAV is given.
