水空跨介质航行器具备在水空2种介质中的运动能力，因此可在海洋领域的监测、救援、资源勘探、环境保护等方面发挥重要作用，具有广泛的应用前景。设计了具有可折叠机臂的回转体结构旋翼航行器——代号为“飞翊”，其拥有水下潜行、水面航行和空中飞行3种工作模式，并能进行多次水空跨越。在总体设计方面，“飞翊”采用回转体设计，以减少其在水中运动阻力和缩小回收储藏空间；采用头部四旋翼和尾部四推进器的动力布局分别实现控制和水下的姿态和运动控制；为了同时保证水中航行效率及空中飞行效率，“飞翊”在水中呈水平姿态航行，在空中呈直立姿态飞行，介质跨越过程采用推进器组合控制进行姿态调整。最后，研制原理样机并进行了水下航行、水面航行、跨介质、空中飞行等多模态验证。试验表明“飞翊”飞行高度为30 m，高度控制精度为±0.1 m，角度控制精度为±0.5°，相较于已有的航行器，在高度与控制精度方面达到了较高的水平。

Cross-medium vehicles， capable of operating in both aquatic and aerial environments， have significant potential for applications in ocean monitoring， rescue operations， resource exploration， and environmental protection， making them valuable in a wide range of fields. This paper presents the design of a rotary-wing vehicle with foldable arms， codenamed “Feiyi”， which can operate in three distinct modes： underwater cruising， surface navigation， and aerial flight， with the ability to transition between air and water multiple times. In terms of overall design， “Feiyi” utilizes a rotary body structure to minimize hydrodynamic resistance during underwater motion and to reduce storage space when retracted. The vehicle features a propulsion system with four rotors at the front for flight control and four thrusters at the rear for underwater attitude and movement control. To optimize efficiency in both water and air， “Feiyi” adopts a horizontal posture for underwater navigation and a vertical posture for aerial flight， with attitude adjustments during medium transitions managed by a combination of thrusters. A prototype was developed and tested in various operational modes， including underwater navigation， surface cruising， cross-medium transitions， and aerial flight. The experiments demonstrated that “Feiyi” can achieve a flight altitude of 30 m with a height control precision of ± 0.1 m and an angular control precision of ± 0.5°， representing a significant improvement in control accuracy compared to existing vehicles.