Experiments in aerial firefighting with and without additives and its application to suppress wildfires near electrical transmission lines

A comparison scheme is proposed to extinguish non-uniform fire scenes and continuously uniform fire scenes using a helicopter’s bucket fire-extinguishing device to spray extinguishing agent. Pure water, and Class AB, gel, and Class A extinguishing agents were added to the bucket fire-extinguishing device to spray 4-layer, 6-layer, and 12-layer wood crib fires. It was discovered that the depth (the distance from the top of the wood crib) of effective cooling and prevention of temperature recovery by extinguishing agents was 0.36 m and that the cooling performance of the extinguishing agents in sequence from high to low was Class A extinguishing agent > gel extinguishing agent > Class AB extinguishing agent > pure water. Their capacity to prevent temperature recovery in the wood crib fires in sequence from high to low was gel extinguishing agent > Class A extinguishing agent > Class AB extinguishing agent > pure water. A device has been developed that can add extinguishing agent to the helicopter bucket efficiently, and its application on-site during the 2020–2021 Spring Festival and other events showed that it can quickly extinguish small-area wildfires near electrical transmission lines to reduce line trips due to wildfire.