Communication technology plays an important role in disaster management to propagate and convey information to the concerned authorities. Considering potential risks and hazards, unmanned aerial systems (UASs) show promise in developing robust and well-defined communication systems for disaster management. However, UASs suffer from achieving long flight times due to limited energy supply. In this paper, we introduce a software-defined UAS model and present a test rig to analyze the energy consumption and the total flight time of the UAS model. The proposed UAS model may provide access to sensitive places where Wi-Fi communication is most needed for rescue operations. A number of UAS models can simultaneously communicate to the base station over the Wi-Fi network. The UAS model is equipped with smart obstacle avoiding assistance and can navigate in a global positioning system (GPS) denied environments to accomplish rescue operations successfully. We conduct indoor simulations of the developed UAS model with mounted light detection and ranging (LIDAR) sensors. Simulation results show that the UAS model is capable of semi-autonomous navigation in an unknown environment with obstacle avoidance. According to the outdoor experimental results, the flight time efficiency with respect to the energy consumption of the UAS model is increased by 47% on average when compared to that of a Matrice 100 quadcopter. This work can be extended to designing commercial products such as controller area network (CAN) electronic speed controllers (ESCs).