Brazilian Warship "Minas Geraes." Strongest Warship ever Built.

Progress, Volume V, Issue 7, 2 May 1910, Page 231

Brazilian Warship " Minas Geraes." Strongest Warship ever Built.

Built by Sir W. G. Armstrong & Co. Ltd. This vessel was handed over to the Brazilian Government by the constructing firm on January sth last according to contract in every respect. She is the most powerful warship yet built, and with the smallest displacement in comparison Moreover, she shows great proof of constructive ability and experience, as one might expect from the fact that all the explosives and ordinance arrangements were in the hands of Sir Andrew Noble, the greatest authority in Britain on the^e matters. Messrs Vickery, Sons, and Maxim, were associated with the Elsw ick firm. They, in fact, designed and constructed the propelling machinery, and they are building the sister ship, the "Sao Paolo." for Ihe Brazilian Navy. The distinctive feature in the design is that the ship cm fire eight twelve inch guns ahead and ten on the broadside, each throwing a projectile of 8251bs weight. No other vessel afloat can fire such a broadside, and no vessel yet built is strong enough to fire i 1 if she possessed the power

Disposition of the Guns The mounting an<l loading arrangements are so good as to require the fullest detailed descriptions We take it from the column*- of our "ontemporary, Engine a ing:— -Forward, as well as aft, it has therefore been possible to tit two gun-houses in the centre line of the ship, these each accommodating two guns of 12-in. bore and 45 calibres in length. Amidships, on each side, there is a similar gun-house, and in order to allow the immense armour hood protecting the ordnance machinery to rotate through 180 cleg., the deck structure is cut away in a semi-circle Otherwise the upper deck of the ship is free of obstruction. This freedom from obstruction is one of the notable features of the ship. Four of the gun-houses are on the upper deck level, but the after of the pair of turrets for ,'ard, and the forward of the pair ot turrets aft, are on a level some 12ft. above these, so that the guns in this case may fire over the guns in front of them (Fig. 1). The centres of the turrets of each pair are about 36ft. apart. Thus eight guns may fire forward, including the four amidships (Fig. 1), eight aft, and ten on either broadside. In this way, it will be recognised, an unusually high proportion of gun-power is utilisable under any conditions of warfare, while the higher elevation of four of the

guns gives them a very considerable advantage. The central superstructure in the ship has been utilised for housing at the forward end. on two different levels, four 4.7 in. guns — two on each side of the bridge — firing forward in line with the keel, with a considerable angle of fire abaft the beam, while aft there are also four such guns similarly arranged Six three-pounder guns have been housed in the superstructure, and two others are placed one on the top of each of the higher 12in. gun-houses, forward and aft. In addition there are on the main deck, and. therefore, within the citadel of 9-in. armour, seven 4. Tin. guns on each side of the ship The upper works forward and aft are indented, in order that the forward and aft 4 Tin guns on each side may fire ahead oi a i tern in line with the keel, as well as on the beam Thovo are in all twenty-two 4. Tin. guns.

The broadside fire, therefore, aggregates ten guns firing 8501b. projectiles, eleven guns firing 451b. projectiles, and six guns using three-pounder projectiles. As in each case great rapidity of fire has been ensured, the armament constitutes the most formidable attack 3 r et provided for in any battleshir* afloat.

The Gun Mountings. The mounting's for the 12-in. guns follow the most recent Elswick practice, with the exception that, to conform to the desire of the Brazilian authorities, electricity is utilised for the training of the turrets; otherwise hydraulic power is applied, and for every operation there is emergency gear either of the hydraulic type or for manual working. In accordance with the latest Elswick practice, air blast is fitted for clear-

ing the gun immediately after each round has been fired ; and there is a water-spray on the rammer, -which plays upon the upturator pad immediately the breech is open, to ensure that any sparks then remaining may at once be extinguished. The guns are arranged to be operated through 18 deg. of elevation, and the gear is so designed that the guns must be loaded at 5 deg. of elevation. The hydraulic power for elevating each gun is normally under the control of the captain of the turret, but for loading operations the main valve is thrown out of gear, so that the gun at once returns to the 5 deg of elevation, and, having been loaded, is again placed under the control of the captain of the turret for elevation to suit the obiective. The recoil is taken up by hydraulic cylinders in the usual way. ' The loading machinery has been worked out with the care characteristic of the Ordnance Department at Blswick, and is on the two-staere system. so that there i« no possibility of the magazine being ieopardi^ed bv any acHdent at the arm-platform. The shell rooms under each turret are subdivided, and in this connection it may be stated that a shellchamber has been arranged between the two engine-rooms. The shells are traversed from tbeir bins bv an overhead hydraulic traverser, using toggle-jaw clips, and arrangements have been made so that this tranverse can be worked by hand. A circular traversing rail is arranged round the hoist-trunk, and the tray for loading the projectile into the hoist-cage travels with the trunk when the" turret is being trained. The door admitting the shot into the cage is interlocked with the cage itself. The charges of ammunition are loaded by hand on the level above the shell-rooms. The charge is put into a hopper in the central portion of the trunk and falls into the upper tray of the hoist-cage. The cage is elevated by an hydraulic ram working through rope gear to the working-chamber level, where the charge and projectile are driven by an hydraulic rammer into the upper or gun-loading hoist-cage, which travels to the gun-loading position on guide-rails, set to the required curvature. The breech of the gun having been opened, the upper travel of the cage tilts a loadingtray into the breech of the gun, in order to protect the screw-thread of the breach. The rammer in use is of the usual chain type, and its first motion locks the cage, which must consequently remain in position until the gun has been loaded. "When the chainrammer is withdrawn from the breech, the cage falls, and the tilting-tray is then automatically withdrawn. The tilting-tray has a locking-bolt fixed to a slide-arm, which locks the valve of the breach opening and closing motor, so that the breech-block cannot be operated during the process of. loading. It will thus be seen that from first to last every action must follow the proper sequence from the moment the charge is -put into the hoist at the base of the turret until the gun is loaded and the breech closed

again. The lower and upper cages can be worked by two distinct hydraulic systems, electricity being used to supply the emergency hydraulic power. The turret is trained by a variable-speed motor, a separate installation of motorgenerators being provided in each turret to supply the current, and there are suitable resistances to compensate for the variable speeds required. The worm-wheel is fitted with friction-plates, which are kept up to

their work by Belleville springs, so that there can be no shock upon the motor should the training-gear come hard back against the stops on the turn-table roller path. On the worm-shaft two bevel wheels are fitted for transmitting, through chain gear, the manual power for training the turrets,. The electric current for training the turrets is supplied from the main electric installation on board the ship, which includes six generating sets, consisting of Elswick engines and

dynamos, the collective electric power being 3600 amperes at 220 volts and 400 revolutions. There are three hydraulic pumps, in separate engine-rooms — two forward and one aft — connected with one system of pipes, the pressure being 10001b. to the square inch. One of these pumps is practieallv sufficient to operate the six turrets Great care has been exercised in connection with the cooling of the magazines, and four of Hall's CO2 machines are provided, with a collective capacity of 300,000 cubic feet of air per hour — a capacity greatly in excess of that hitherto fitted. This is due to the hot climate in which the ship will usually bo servins:. Part of this cooling capacity may be utilised in connection with the food stores.

Armour. A special feature of the turrets is the large space allowed for the operations. The gun-house* seem larger than usual The side plating iei c in one piece, Avhile the tops are in two pieces only, with a junction down the centre. The front, being 12in. thick has had to "be made in three pieces, to form the gun-ports The broadside armour amidships is Oin in thickness for a depth of over 22ft 4in ,

s£t. of which is now below the normal load water-line. Forward and aft there is a transverse bulkhead, 9in. thick, enclosing the belt it is reduced first to 6in., and then to 4in. at the ends. The upper strake amidships, extending to the top deck, is also 9in. armour, and within the citadel thus formed are the 4.7 in. guns on each side. There are two protective decks, the waterline deck being 2in. thick and the upper one l^in. thick. The whole of the armour was manufactured at the Openshaw Works of Sir W. G. Armstrong, Whitworth, and Co., and the 9in. plates on their trial were subjected to three rounds, the striking energy in each case being 9300 foot-tons. So satisfactory was the resistance to this attack that it was decided to fire a supplementary round, with a striking energy of 10,300 foot-tons. The result of this was exceptionally satisfactory, the penetration in no ease exceeding 2y 2 in. During the trials in the North Sea" the seas were so heavy that the spray washed the upper bridges 60 feet above the water line. The ship behaved with remarkable steadiness throughout.

Gun Trials. The account of these is of great interest, in consequence of the great number and large calibre of the guns, as well as the success all round. The trials began with the 3 pounders and 4.7 in. guns. The ship carries twenty-two of the latter, fourteen of which are on the

main deck, well protected behind armour, and the remaining eight are on the upper deck and superstructure, protected by large shields. After each gun had been separately fired twice, broadsides were fired from each side. There was no hitch or difficulty of any description; the breeches were easy to work*, and the loading was very quickly performed.

The trials of the 12in. guns Avere afterwards carried out, two rounds being first fired from each gun in succession. A view taken when the port beam guns were being fired is given in Fig. 6. This illustration is specially interesting, as it shows the wings of the navigating bridge removed for action, and the boats discarded, and the davits swung back out of the way This view should be compared with Fig. 1. Afterwards five turrets were all trained on the port beam, each gun being given an elevation of 7 deg. and loaded with full charge. These guns were all fired simultaneously, which constituted the heaviest broadside ever fired by a warship. When it is recollected that each gun fired a shot of 8501b. weight, and a charge of 2851b. of cordite, it will be readily understood what an imposing sight this broadside was. This is the first occasion of the simultaneous firing of ten 12-in. guns on the broadside, as this is the first ship upon which such a performance was possible Tbe illustration. Fig. 7/ is therefore unique ; it is a view looking forward. The sixth turret was used for firing with rapidity and accuracy. Excellent shooting was made in very creditable time. Another trial of great interest was the firing of one pair of 12in. guns immediately over another 12in. turret. Some little apprehension existed in the minds of gunnery men as to the effect that the blast might have on the crew of the lower turret, but the experiment clearly showed that the crew might have remained in their turret, and have suffered no inconvenience whatever, in spite of the large guns being fired at a distance of only 4ft. or sft above their heads. The heavy roof of the lower turret was proved to be an ample protection, and in no way suffered from the explosion above it. This trial evoked so much interest that representatives from foreign countries had obtained special permission to come on board and witness it. Fig. 8 will be studied with care by those who thought that the placing of two pairs of guns at the forward and after end, within 36ft. of each other, on the same bearing fore and aft. would result in the flash fro;n the forward pair interfering with the aiming of the after pair. The view shows the four guns at the after end firing in the same bearing astern. In the foreground there is the smoke from the after funnel, but the port gun in each pair is easily seen. The views in Figs. 8 and 9 afford sharp contrast betAveen war and peace conditions.

The Dimensions of the Ship. Length ovei a 1 1... ... ... 543 ft Length between pei pendicnlais ... SOOit Bieadth, moulded ... ... 83ft Depth, moulded ... ... 42ft. 3m Draught ... ... ... 25ft. Displacement ... . .. 19,280 tons Speed ... ... . ... 21 knots . Noimalcoalpapacih on this draught 800 tons Total bunkers capacity ... ... 23G0 tons

Speed Knots 48-houis' tnal at 10 knots ... 10 468 Average of six measured-mile runs on 10-knots trial ... 10 G23 30-houis' trial 19 13 Six measured - mile runs on this trial 19 35 8-hours' natural-di aught trial 20 762 Mean of six runs on tins trial 20.863 Full - power forced - draught trial at 2501b. pressure, mean of six mile runs ... 21.189 Forced-draught trial at 2801b Indicated Bevolu- Hoi setions Power C 6.3 2,495 G7.28 2,683 126 9 16,177 128. 2G 16,352 137.85 21,265 138.5 20,948 140 07 25,519 pressure 21.432 147.47 27,212

Results of Steam Trials.