Sí, así era...
Mark 13 Air Launched Torpedo.
This 2,200 pound weapon had been introduced in 1938, had not been adequately tested, but was the only one available. Its use required release at less than 60 feet and slow air speed. Over a year after the Battle of Midway and after some improvements, the Bureau of Ordinance ran a test with over 100 torpedoes and found only 31 percent gave a satisfactory run. Add to this -- exploder problems and erratic launches under fire against evading targets -- it is no wonder that dive bombing became the attack method of choice.
-- "Black Cat Raiders" by R. C. Knott
The Mk 13 aerial torpedo design dated from the early 1930s. It was stubby. It's warhead originally carried 400 pounds of TNT, later 600 pounds of Torpex, that made it nose-heavy. Fleet squadrons limited drops to 50 feet at no more than 110 knots from a range of approximately 800 yards. Performance was so bad (until improved in 1944) as to make American torpedo-plane attacks well nigh futile.
-- "Unknown Battle of Midway" by Alvin Kernan
Air Attacks
Lea -- 13 launched, one hit ; in harbor
Tulagi -- 22 launched, one hit ; in harbor
Shoho -- 24 launched, 7 hits ; already damaged by bombs
Shokaku -- 20 launched, no hits.
Midway -- 51 torpedoes carried, no hits, 43 planes lost.
Suzuya -- 6 torpedoes, improved Mod 2, three reported explosions. Japanese reported no hits.
Tactical Problem . The torpedo was so slow and short range that a warship could outrun one of our torpedoes when not launched from ahead. The TBD Devastator torpedo bomber was too slow to get ahead of a turning ship. The torpedo made a clear wake allowing ships to steer away from its path. Some were observed in clear water on stationary targets to go under the enemy ship and detonate on the other side. Slow air speed allowed fighters to easily catch the torpedo bombers and shoot them down and a required approach to 800 yards allowed hits from all calibers of ship-borne anti-aircraft guns. The model 2 was introduced after Midway : many reported hits were actually premature explosions, according to Japanese records. Therefore many reported hits and sinkings were false.
Further improvements in 1943 allowed air drops at higher speeds and altitudes and resulted in 40% hit rates. The six engagements listed above with 136 torpedoes scored 7%, sinking only transport Yokohama Maru, destroyer Kikuzuki, and light carrier Shoko.
Type 91
The most extensive damage received by the Pacific Fleet's capital ships on December 7th was inflicted by aerial torpedoes dropped from the Nakajima Type 97 torpedo bomber, known in the West as "Kate." In employing their Type 91 aerial
torpedoes the Japanese had had to correct the tendency of the torpedoes, when dropped, to plunge too deep in the water before ascending to their programmed attack depth. The water depth at Pearl Harbor was 30 feet, except in the channels, where it was 45 feet. The successful British aerial torpedo attacks at Taranto, Italy, on 12 November 1940 had been made in depths of 84 to 90 feet, with a few runs made at 66 to 72 feet depths. (The Japanese studied the site and took photographs, but said after the war that Taranto had had no influence on their own tactics for Pearl Harbor.) Unless some modifications were made to the Japanese torpedoes it was certain that they would dive uselessly into the muck at shallow Pearl.
Still one more refinement was required, and that was finding what should be the pilot's correct altitude, airspeed, and trim for making the drop. Sometime during the period 11-13 November 1941 the answers were found--20 meters (66 feet) off the deck at 100 knots and with trim set to place the torpedo in the water at 17-20 degree incidence. It was a tactic worked out just in time, since to make an aerial torpedo attack at Pearl Harbor on 8 December, carriers would have to depart by November 26.
Japanese estimated that, out of the 40 drops planned for Pearl Harbor, 27 torpedoes would hit home. (In the actual attack, there were 36 successful drops, of which 25 scored hits; 11 missed, malfunctioned, or bore into the muck; four met unknown fates.)
This torpedo was nonetheless a good weapon, reliable and with a high maximum launch speed. However, contrary to Japanese expectations, a single hit was not capable of penetrating the torpedo protection of American battleships. In the attack on Pearl Harbor, Nevada was hit by a single Type 91 Mod 2 that split seams and caused leaks, but did not penetrate the holding bulkhead. California was hit by two Type 91 Mod 2 torpedoes that deflected the holding bulkhead inwards but left it intact. California sank only because the hatches to the void spaces of the underwater protection system had been left open for an upcoming inspection, allowing extensive flooding that would not have taken place had the ship beenin watertight condition.
Mk13, Mk13a
30m, 205 km/h
• Mk13 late
180m, 400 km/h
(this torpedo had a much wider range of drop than the early one)
• Type91
30m, 240 Km/h
• Type91 late
60m, 330 km/h
(this torpedo had a much wider range of drop than the early one)
