DaveBrt
1st Lieutenant
- Joined
- Mar 6, 2010
- Location
- Charlotte, NC
Charleston Mercury, October 16, 1862
Iron-Clad Frigates -- Bending their Armor Plates
[From the Scientific American]
The steam frigate Roanoke, which is now in the Navy Yard at Brooklyn, has been razeed, and is being converted into an iron-clad turret warship. She is to be clothed amidships with thick iron plates, which are to extend about five feet below the water line; and she will have three great revolving gun turrets on deck, and a powerful iron beak or ram on her bow. This beak resembles a huge axe, and is formed of plates 20 feet long, four and a half inches thick, thus making nine inches of iron on the front edge. Each of the revolving gun turrets will be twenty feet inside diameter, and the sides will be formed of eleven courses of inch thick plates.
These plates are laid over and rivetted to one another in such a manner as to "break joints," and her vertical plates are also bolted to several courses so as to secure the whole in the most rigid and perfect manner. These gun towers for the Roanoke are now being constructed at the Novelty Works, in this city, where the plates for them, likewise those for the armor, are bent to the proper curves. Each plate for a turret is about nine feet in length by forty inches in width, and an inch in thickness. Two courses of rivet holes are punched out in each, and they are all bent cold in a powerful hydraulic press. The bed plate of the press is of a concave form, and the top block is of a convex form.
A plate to be bent is placed upon the concave bed plate of the press, and when properly adjusted the pump forces up three rams under it, and the plate is reduced to the proper curve against the top plate. The pressure to which each plate is submitted, to give it the proper curve, is three and a half million pounds (1750 tons). By this method of bending the turret plates cold, there is perfect uniformity and accuracy secured for the whole. The turrets for the Roanoke will be of a superior character, but only six courses of plates have as yet been laid on two of them.
The bending of the thick plates for the ram, and also for the sides of the frigate, is quite a different and difficult operation to perform compared with those of the gun towers. Each of these plates has to be bent to the proper curve to suite its own particular place on the vessel, and not only the broadside but the edges also must be bent to suit the particular curves. The bending operations are under the charge of Mr. George Bonniwell, an intelligent young shipwright. All these plates are hammered iron, and are furnished by several companies in Pa., NY and Mass. When they arrive the resemble huge straight iron slabs, varying in length from eleven to twenty-two feet, and in breadth from twenty-two to twenty-four inches, and their average thickness is four and a half inches. One of eleven and a half feet in length weighs about 4210 pounds, one of twenty-two feet, for the ram, weights over four tons. Such masses of iron are difficult to move about, and the operations connected with bending them are necessarily tedious and troublesome; and they require great care and skill to conduct properly. Of course it is impossible to bend such mass of iron cold, hence each plate is heated to nearly a white heat in a long furnace, shaped somewhat like a baker's oven, with a moveable arched cover.
The press for bending is quite different from the ones used for bending the turret plates. Outwardly it resembles a long, strong iron screw press, used for pressing woolen cloth. Its top block or platen, is moved up and down, , but its bed is fixed and very solid. A dudgeon hydraulic jack at each end supports and moves the block up and down. The bed upon which the heated plate is laid, is formed of series of adjustable bolster blocks, each of which is capable of being set by a screw to any desired height on either side, and at any desired angle to suite the bend to be given to a plate which is compressed between the descending top block and the adjustable bed. A plate is first placed in the furnace, and it is then raised to nearly a white heat. The cover of the furnace is now raised by a block and tackle, and the plate is then seized by a powerful crane, secured on a carriage. The heated plate is now lifted, the crane carriage moved back, and the plate swung around and placed in the press, where it is perfectly adjusted to obtain the proper curve. The huge top block is thus forced down, squeezing the great mass of iron into the desired shape.
In about half an hour the plate has acquired a permanent set, and it is taken out, ready to have its edges planed, when it is fit for bolting to the frigate. The port holes in these plates are all drilled. It requires a large number of men to move such a great mass of iron, and from the time a glowing plate is lifted out of the furnace until it is secured in the press, the scene is one of extraordinary activity and excitement, as the plate requires to be placed in the press as expeditiously as possible before it becomes cool. The metal of these plates appears to be first-class; but until within a few days past they were furnished very slowly by the various contractors. The plating of the Roanoke will now proceed with greater rapidity; still she will not be finished for several months to come. We are told that this frigate is expected to obtain a speed of ten knots per hour. If she makes nine knots we will be agreeably disappointed. As the Roanoke will sit very low in the water, we hope that proper arrangements will be made for ventilation on the main deck. The defects on the Monitor and Galena, so clearly pointed out in the Scientific American of last week, will be reproduced in the Roanoke, rendering her very deficient as a "sea-boat," unless this advice is heeded.
Iron-Clad Frigates -- Bending their Armor Plates
[From the Scientific American]
The steam frigate Roanoke, which is now in the Navy Yard at Brooklyn, has been razeed, and is being converted into an iron-clad turret warship. She is to be clothed amidships with thick iron plates, which are to extend about five feet below the water line; and she will have three great revolving gun turrets on deck, and a powerful iron beak or ram on her bow. This beak resembles a huge axe, and is formed of plates 20 feet long, four and a half inches thick, thus making nine inches of iron on the front edge. Each of the revolving gun turrets will be twenty feet inside diameter, and the sides will be formed of eleven courses of inch thick plates.
These plates are laid over and rivetted to one another in such a manner as to "break joints," and her vertical plates are also bolted to several courses so as to secure the whole in the most rigid and perfect manner. These gun towers for the Roanoke are now being constructed at the Novelty Works, in this city, where the plates for them, likewise those for the armor, are bent to the proper curves. Each plate for a turret is about nine feet in length by forty inches in width, and an inch in thickness. Two courses of rivet holes are punched out in each, and they are all bent cold in a powerful hydraulic press. The bed plate of the press is of a concave form, and the top block is of a convex form.
A plate to be bent is placed upon the concave bed plate of the press, and when properly adjusted the pump forces up three rams under it, and the plate is reduced to the proper curve against the top plate. The pressure to which each plate is submitted, to give it the proper curve, is three and a half million pounds (1750 tons). By this method of bending the turret plates cold, there is perfect uniformity and accuracy secured for the whole. The turrets for the Roanoke will be of a superior character, but only six courses of plates have as yet been laid on two of them.
The bending of the thick plates for the ram, and also for the sides of the frigate, is quite a different and difficult operation to perform compared with those of the gun towers. Each of these plates has to be bent to the proper curve to suite its own particular place on the vessel, and not only the broadside but the edges also must be bent to suit the particular curves. The bending operations are under the charge of Mr. George Bonniwell, an intelligent young shipwright. All these plates are hammered iron, and are furnished by several companies in Pa., NY and Mass. When they arrive the resemble huge straight iron slabs, varying in length from eleven to twenty-two feet, and in breadth from twenty-two to twenty-four inches, and their average thickness is four and a half inches. One of eleven and a half feet in length weighs about 4210 pounds, one of twenty-two feet, for the ram, weights over four tons. Such masses of iron are difficult to move about, and the operations connected with bending them are necessarily tedious and troublesome; and they require great care and skill to conduct properly. Of course it is impossible to bend such mass of iron cold, hence each plate is heated to nearly a white heat in a long furnace, shaped somewhat like a baker's oven, with a moveable arched cover.
The press for bending is quite different from the ones used for bending the turret plates. Outwardly it resembles a long, strong iron screw press, used for pressing woolen cloth. Its top block or platen, is moved up and down, , but its bed is fixed and very solid. A dudgeon hydraulic jack at each end supports and moves the block up and down. The bed upon which the heated plate is laid, is formed of series of adjustable bolster blocks, each of which is capable of being set by a screw to any desired height on either side, and at any desired angle to suite the bend to be given to a plate which is compressed between the descending top block and the adjustable bed. A plate is first placed in the furnace, and it is then raised to nearly a white heat. The cover of the furnace is now raised by a block and tackle, and the plate is then seized by a powerful crane, secured on a carriage. The heated plate is now lifted, the crane carriage moved back, and the plate swung around and placed in the press, where it is perfectly adjusted to obtain the proper curve. The huge top block is thus forced down, squeezing the great mass of iron into the desired shape.
In about half an hour the plate has acquired a permanent set, and it is taken out, ready to have its edges planed, when it is fit for bolting to the frigate. The port holes in these plates are all drilled. It requires a large number of men to move such a great mass of iron, and from the time a glowing plate is lifted out of the furnace until it is secured in the press, the scene is one of extraordinary activity and excitement, as the plate requires to be placed in the press as expeditiously as possible before it becomes cool. The metal of these plates appears to be first-class; but until within a few days past they were furnished very slowly by the various contractors. The plating of the Roanoke will now proceed with greater rapidity; still she will not be finished for several months to come. We are told that this frigate is expected to obtain a speed of ten knots per hour. If she makes nine knots we will be agreeably disappointed. As the Roanoke will sit very low in the water, we hope that proper arrangements will be made for ventilation on the main deck. The defects on the Monitor and Galena, so clearly pointed out in the Scientific American of last week, will be reproduced in the Roanoke, rendering her very deficient as a "sea-boat," unless this advice is heeded.
Bringing the