A valve mountable to a bottom of a container around an opening, such as an aerial firefighting bucket, and has a hub and telescoping arms extending radially from the hub. The telescoping arms are connected to the hub and to the bottom of the container. Hence, they radiate from the hub to a periphery around the opening. The hub may be raised and lowered with respect to the opening. When raised the telescoping arms extend and when lowered the telescoping arms contract. A valve flap is connected to the telescoping arms and covers the opening when the hub is lowered to inhibit liquid flow out of the opening and exposes part of the opening as the hub is raised to allow liquid to flow past the valve flap.