Published Resources Details Journal Article
- Title
- The Ericsson Pneumatic Torpedo
- In
- Scientific American
- Imprint
- 19 December 1874, p. 390
- Description
Accession No.1636
- Abstract
"The body of the torpedo consisted of a box of thin steel plates, 8 feet 6 inches long, 30 inches deep, and 20 inches wide. The explosive was placed in the bow. During the experiments a block of wood 27 inches long represented the containing vessel. A tapering block 18 inches long and secured to the rear of the box formed the stern, immediately aft of which were the propellers. These were two bladed and 3 feet 6 inches in diameter with a pitch of 5 feet. Both revolved around a common centre, yet in opposite directions, a necessary condition since the powerful rotary movement of a single screw would cause the small hull to heel and probably revolve unless retained in a vertical position by the ingenious expedient of causing the rotary tendency of one propeller to counteract the other. The displacement was greater than might have been supposed, considering the small dimensions of the body, 2,000 pounds being barely sufficient to balance the weight of the whole apparatus The motive power was a small double cylinder-oscillating engine, driven by compressed air, which was transmitted through a tubular cable, connected just abaft of the stern (see illustration). The air pressure also governed an equipoise rudder, secured under the bottom and near the bow. The steering was affected by applying the force of the air against the tiller on one side, which was counteracted by the tension of a spring on the opposite side. The action of the apparatus was such as to be wholly independent of the differential force of the compressed air and the spring tension, and was set in motion by admitting more or less air into the cable, thereby opening more or less, a small connecting valve. The submersion was regulated by two horizontal rudders turning on a transverse axle, which projected from each side near the bow. These wings or rudders were so contrived and governed that they kept the torpedo at a depth of 7 to 12 feet below the surface, and were provided with automatic devices so that the latter limit could not be exceeded. In order that the course of the torpedo could be noted a light steel mast terminated with a green ball, the forward side of which was painted sea green so as not to be perceptible to the enemy, and the rear white so as to be easily distinguished above the water by those dispatching the torpedo."