Design_and_description HSwMS_Tirfing_(1866)

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, had been born in sweden, although had become 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). john ericsson 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

tirfing, , sister ship thordön, briefly armed pair of 267-millimeter (10.5 in) m/66 smoothbore guns before being rearmed in 1873 2 240-millimeter (9.4 in) m/69 rifled breech loaders, derived french design. weighed 14,670 kilograms (32,340 lb) , fired projectiles @ muzzle velocity of 397 m/s (1,300 ft/s). @ maximum elevation of 7.5° had range of 3,500 meters (3,800 yd). improved version developed in 1870s; guns heavier, 16,688 kilograms (36,791 lb), had higher muzzle velocity of 413 m/s (1,350 ft/s). coupled increased elevation of 11.29°, gave them range of 5,000 meters (5,500 yd). tirfing received guns in 1885.

in 1877 each monitor received pair of 10-barreled 12.17-millimeter (0.479 in) m/75 machine guns designed helge palmcrantz. each machine gun weighed 115 kilograms (254 lb) , had rate of fire of 500 rounds per minute. projectiles had muzzle velocity of 386 m/s (1,270 ft/s) , maximum range of 900 meters (980 yd). these guns replaced during 1880s 4-barreled 25.4-millimeter (1.00 in) m/77 nordenfeldt gun, enlarged version of palmcrantz s original design. 203-kilogram (448 lb) gun had rate of fire of 120 rounds per minute , each round had muzzle velocity of 490 m/s (1,600 ft/s). maximum range 1,600 meters (1,700 yd).

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.