Among other projected weapons intended to attack airships from above, including Ranken darts and small incendiary bombs, was the "Fiery Grapnel". Developed at the Royal Aircraft Factory, the grapnel consisted of a two-inch long hollow steel shaft packed with an explosive charge and fitted with a sharp four-sided nose and metal plates that acted as fins; this would have been attached to a winch-mounted cable and carried by a single B.E.2. It was intended for the fighter to approach a Zeppelin from above, after which the grapnel would be dropped and appropriate manoeuvring employed to strike the surface of the Zeppelin with it: it then would bury itself and explode, causing ignition of the airship's hydrogen gas.