Design_and_description HNoMS_Mjølner_(1868)

1 design , description

1.1 propulsion
1.2 armament
1.3 armor

design , description

the john ericsson-class ironclads designed meet need of swedish , norwegian navies small, shallow-draft armored ships capable of defending coastal waters. standoff between uss monitor , larger css virginia during battle of hampton roads in, 1862, roused interest in sweden in new type of warship, seemed ideal coastal defense duties. john ericsson, designer , builder of monitor, born in sweden—although becoming american citizen in 1848—offered share design swedes. in response, sent lieutenant john christian d ailly united states study monitor design , construction under ericsson. d ailly arrived in july 1862 , toured rolling mills, gun foundries, , visited several different ironclads under construction. returned sweden in 1863 having completed drawings of monitor-type ship under ericsson s supervision.

the ship measured 60.88 meters (199 ft 9 in) long overall, beam of 13.54 meters (44 ft 5 in). had draft of 3.4 meters (11 ft 2 in) , displaced 1,522 metric tons (1,498 long tons). mjølner divided 9 main compartments 8 watertight bulkheads. on time flying bridge and, later, full superstructure, added each ship between gun turret , funnel. crew numbered 80 officers , men, increased 104 modified additional weapons.

propulsion

the john ericsson-class ships had 1 twin-cylinder vibrating lever steam engines, designed ericsson himself, driving single four-bladed, 3.74-meter (12 ft 3 in) propeller. engines powered 4 fire-tube boilers @ working pressure of 40 psi (276 kpa; 3 kgf/cm). engines produced total of 380 indicated horsepower (280 kw) gave monitors maximum speed of 6.5 knots (12.0 km/h; 7.5 mph) in calm waters. ships carried 110 tonnes (110 long tons) of coal, enough 6 day s steaming.

armament

mjølner armed pair of armstrong 270-millimeter (10.6 in) rifled muzzle-loading guns. each gun constructed of steel , weighed 18.5 long tons (18.8 t). ship carried 80-millimeter (3.1 in) gun. during mjølner s reconstruction in 1897 gun turret fixed in place , modified serve barbette 2 new breech-loading cockerill 120-millimeter (5 in) guns. received 2 124-millimeter (4.9 in) , 65-millimeter (2.6 in) cockerill guns mounted in superstructure. in addition 2 37-millimeter (1.5 in) hotchkiss 5-barrel revolving guns mounted in superstructure. fired shell weighing 1.1 lb (0.50 kg) @ muzzle velocity of 2,000 ft/s (610 m/s). gave them range of 3,500 yards (3,200 m). had rate of fire of 30 rounds per minute

armor

the john ericsson-class ships had complete waterline armor belt of wrought iron 1.8 meters (5 ft 11 in) high , 124 millimeters (4.9 in) thick. armor consisted of 5 plates backed 91 millimeters (3.6 in) of wood. lower edge of belt 74.2 millimeters (2.9 in) thick 3 plates thick. maximum thickness of armored deck 24.7 millimeters (1.0 in) in 2 layers. gun turret s armor consisted of twelve layers of iron, totalling 270 millimeters (10.6 in) in thickness on first 4 monitors. inside of turret lined mattresses catch splinters. base of turret protected 127-millimeter (5.0 in) glacis, 520 millimeters (20.5 in) high, , turret s roof 127 millimeters thick. conning tower positioned on top of turret , sides ten layers (250 millimeters (9.8 in)) thick. funnel protected 6 layers of armor total thickness of 120 millimeters (4.7 in) half height.