Kaiten - "Turn Toward Heaven"

The Human Torpedo

The design of the Japanese Kaiten was originally based on the highly successful surfaced-launched Type 93 "Long Lance" torpedo. Nearly 400 Type 1's were built, and were the only type used operationally. The Type 4 oxygen-kerosene engine produced 1,500 horsepower on one shaft. Top speed was 40 knots. Range for Type 4 is listed as 38.52 miles at 20 knots, 23.61 miles at 30 knots, and 16.78 miles at 40 knots. The warhead contained 3,960 pounds of TNT. Approximately 45-50 Type 4's were built in 1945, but were never used operationally. An escape hatch was not provided for Kaiten built late in the war, and in any case, no pilot is known to have attempted to escape from his speeding torpedo as it approached its target. Many Type 4 weapons were found at the Kure Naval Base after the War.

Kaiten were carried piggyback aboard mother submarines, and possibly aboard a few surface ships adapted for that purpose. At least three could be carried at a time on one mother sub; some I-boats carried as many as six Kaiten. Maximum depth was 264 feet, which placed that limit on the mother boat. The most successful attack was the sinking of the fleet tanker Mississinewa in Ulithi anchorage on 20 November 1944; the destroyer escort Underhill was also sunk on 24 July 1945. A few other ships were damaged. In the Japanese human torpedo program, eight mother submarines and almost 900 lives were lost.