Investigation of Wind Flow Conditions on the Flight Endurance of UAVs in Hovering Flight: A Preliminary Study

Over the past decade the use of Unmanned Aerial Vehicles (UAVs) for the inspection of turbine blades has been registering steady progress and is fast becoming a well-established inspection methodology especially at offshore wind farms. A UAV operating in the open field is subject to varying ambient conditions which have an effect on the power required to maintain stable flight. This may have an impact on the flight endurance of the UAV, especially when operating in windy conditions. Simulations are a very useful tool for estimating the impact of such ambient conditions on the performance and flight endurance of a UAV. However, it is extremely difficult to accurately model all the dynamics at play in the open field where flow conditions are highly stochastic. Few open field studies necessary to validate such simulation models have been carried out to date in this regard. In this study, the impact of open field wind conditions on the flight endurance of a hovering UAV is investigated. The test vehicle used in this study is a quadrotor UAV, which was fitted with an array of sensors to monitor power consumption parameters of the propulsion motors whilst the vehicle is hovering at a fixed altitude above the ground. The quadrotor was also fitted with an ultrasonic wind sensor in order to measure the relevant wind parameters that the quadrotor was being subjected to during the hovering study. The test UAV was flown in different ambient conditions to establish the impact on the UAV flight endurance when subjected to different wind speeds. Results from a series of UAV test flights in the open field indicated that the power required by the UAV to maintain hovering flight decreases as the wind speed increases.