A UAV having a fuselage body including a cavity that forms a cargo bay for transporting a payload, and a lower access opening providing an exit for the payload from the cargo bay, the lower access opening including a lower cargo bay door, an actuator positioned in the fuselage body, a linkage assembly connected to the actuator and connected to the lower cargo bay door, wherein the actuator and linkage assembly are operable to open and/or close the lower cargo bay door, wherein a first horn is mounted to the actuator, and wherein the linkage assembly includes a first linkage member having a first end and a second end, the first end of the first linkage member pivotally attached to the first horn and the second end of the first linkage member pivotally attached to the cargo bay door.