Abstract: A coaxial tilt-rotor unmanned aerial vehicle (CTRUAV) and a control method thereof. CTRUAV comprises three rotor modules, five rotors with motors respectively and a control system. Three rotor modules are in an inverted triangle layout. The left and right coaxial tiltable rotor modules in the front of the CTRUAV can rotate around the plane of a fuselage. A rear rotor is installed on the rear fixed-axis rotor module. Two pairs of coaxial rotors are respectively installed on the left and right coaxial tiltable rotor modules. Namely, the left and right coaxial tiltable rotor modules consists of an upper rotor and a lower rotor respectively; the upper rotor and the lower rotor have opposite rotation directions and the same rotation speed during the flight. Moreover, in the two pairs of coaxial rotors, the rotors on same layers have opposite rotation directions, and therotors on different layers have the same rotation directions.

Abstract: An air, sea and underwater tilt tri-rotor UAV capable of performing vertical take-off and landing. By the method for controlling a submerged floating device and a tilt tri-rotor device, the UAV is switched among the vertical take-off and landing mode, fixed wing mode, water surface sailing mode and underwater submerging mode.

Abstract: An underwater launching apparatus for a small unmanned aerial vehicle capable of floating on water, having an airbag, inflating module, airbag arm, cylindrical body, upper baffle plate, spring, airbag arm connecting rod, lower baffle plate, upper buckle and lower buckle. This apparatus has compact and reliable structure. Relative to a traditional underwater catapult, the apparatus has smaller body and completes deployment and ejection of the launching apparatus by means of elasticity of the spring. The underwater launching apparatus for the small unmanned aerial vehicle has high stability and diversified applications. After the airbag arm of the catapult is deployed on the water and the inflating module inflates the airbag, developed area is larger and resistance to wind and waves is stronger. In a deployed state, a sensor on the unmanned aerial vehicle can be matched and steadily deployed on the water for investigation.

Abstract: An air, sea, land and underwater tilt tri-rotor UAV capable of performing vertical take-off and landing. By the method for controlling a submerged floating device and a tilt tri-rotor device, the UAV is switched among the vertical take-off and landing mode, fixed wing mode, water surface sailing mode and underwater submerging mode, thereby making same have the advantages of four kinds of UAVs, and enhancing the applicability, maneuverability and efficiency of UAV. This has high efficiency in power system, has obviously improved endurance time and flight distance as compared with the traditional multi rotor UAV because of having the fixed wing mode, is applicable to more scenarios, and may operate on flat land, mountain land, water surface and underwater, thereby completing designated missions such as aerial, ground, water surface and underwater investigation, survey and concealment.