Ko-hyoteki class submarine

From Wikipedia, the free encyclopedia

Ko-hyoteki class submarine
Ko-hyoteki class submarine grounded in the surf on Oahu after the Attack on Pearl Harbor, December 1941.
Class
Lead Ship:
Builders:
Number of Ships:
General characteristics
Displacement:	46 tons submerged
Length:	23.9 m (78.5 ft)
Beam:	1.8 m (6 ft)
Height:	3 m (10.2 ft)
Ballast:	5,899 lb (2,670 kg) in 534 × 11 lb (5 kg) lead bars
Designed depth:	30 m (100 ft)
Propulsion:	192 trays of two two-volt cells each, 136 trays forward, 56 trays aft; one electric motor, 600 horsepower (450 kW) at 1800 rpm, two screws conter-rotating on single shaft, leading prop 1.35 m diameter, right-handed; trailing prop 1.25 m diameter, left-handed
Speed:	23 knots (43 km/h) surfaced, 19 knots (35 km/h) submerged
Range:	100 nautical miles at 2 knots (190 km at 4 km/h), 80 nautical miles at 6 knots (150 km at 11 km/h), 18 nautical miles at 19 knots (33 km at 35 km/h)
Complement:	2
Armament:	2 × 18 in (457 mm) torpedoes muzzle-loaded into tubes, one 300 lb (140 kg) scuttling charge

The Ko-hyoteki (甲標的, "Type 'A' Target") class of Japanese midget submarines had hull numbers but no names. For simplicity, they are most often referred to by the hull number of the mother submarine. Thus, the midget carried by I-16 was known as the I-16 midget. The midget submarine hull number began with the character "HA", but is visible only on the builder's plate inside the hull.

Fifty were built. The "A Target" name was assigned as a ruse—if their design was prematurely discovered by Japan's foes, the Japanese Navy could insist that the vessels were battle practice targets. They were also called "tubes" and other slang names.

The first two, Ha-1 and Ha-2, were used only in testing. They did not have conning towers, which were added to the later boats for stability underwater.

Ha-19 was launched by the I-24 at Pearl Harbor. Most of the other fifty hull numbers are unaccounted for, although two were captured in Sydney (Australia), and others in Guam, Guadalcanal, and Kiska Island, accounting for some of the other hull numbers.

The submarines were each armed with two 17.7 inch (450 mm) torpedoes in muzzle-loading tubes one above the other on the port bow. In the Pearl Harbor attack the specially designed type 97 torpedo was used, but problems with the oxygen flasks meant that all later attacks used the type 91 torpedo designed for aircraft launching. There was also a demolition charge which it has been suggested was large enough to enable the submarine to be used as a suicide weapon, but there is no evidence that it was ever used as one.

Five of these boats participated in the Pearl Harbor attack, with one actually making into the harbor. Of the five used at Pearl Harbor, HA-19 was captured, and the other four sank or were lost. "During World War II, HA-19 was put on tour across the United States to help sell War Bonds..." [1]. Now a US National Historic Landmark, HA-19 is now an exhibit at the National Museum of the Pacific War. [2].

A photograph taken from a Japanese plane during the Pearl Harbor attack appears to show a midget submarine inside Pearl Harbor firing torpedoes at Battleship Row. According to analysis conducted by the United States Naval Institute in 1999, the midget submarine may well have scored a direct hit on the USS West Virginia. This conclusion is disputed by several noted historians on the Pearl Harbor Attacked Message Board linked below. Only one submarine is known to have penetrated the harbor and it fired its torpedoes at the USS Curtiss and USS Monaghan. Another sub fired its torpedoes at the USS St. Louis as she exited the harbor. The remaining three subs (the one captured, one found in 1960 and one found in 2003) had their torpedoes onboard when found. That accounts for the torpedoes of all five submarines, effectively proving that the photo interpretation is spurious.

In May 1942, Type A midget submarines were also used to strike at Allied shipping in Sydney, Australia, and attack the Allied campaign in Madagascar.