Gravesend To Blyth Sands Isle Of Grain 55
Some time after 1887, a launching station for the Brennan torpedo, a weapon which has been described as "the world's first practical guided missile" (fire by wire) was added to the fort. One of the magazines was converted into a chamber for the engine room with ancillary chambers for other machinery. One of the emplacements in the open battery also had to be taken out of service. A large concrete room was built onto the front of the fort to store the torpedoes, which were launched from a rail mounted on the roof of the torpedo room. Flank walls were added to the roof to protect the launch crews from enemy fire. Two slipways were built at different times, the second being added most likely in the 1900s, along with a telescopic control tower on the roof to direct the torpedoes. The torpedo had two propellers, rotated by wires which were attached to winding engines on the shore station and which played out after the torpedo was fired. By varying the speed at which the two wires were extracted, the torpedo could be steered to the left or right by an operator. Today only one of the slipways, along with the launching rails and vestiges of the tower are visible; the other slipway has long been in-filled. Only one example of the torpedo itself exists, which can be viewed at the Royal Engineer's Museum Chatham.