North American B-25 Mitchell #43-3981 “Lucky Legs” of the 47th Bombardment Squadron, 41st Bombardment Group, 7th Air Force, prepares to take off from Ryuku Retto, Okinawa for a mission against Sasebo Harbor on Kyushu in the Japanese Home Islands, 28 July 1945. Lucky is carrying a Mark 13/44 GT-1 (glide torpedo), a weapon the particular plane used for the first time, in this mission.
[Source: USAF Photo via Mark Allen Collection]
While primarily a Navy-dropped weapon, the Mark 13 was used by the Army in a few instances, such as the 41st BG’s B-25s, and by B-26 Marauder units at Midway and in the Aleutian Islands, the Southwest Pacific, North Africa, and the Mediterranean, with limited success.
Mark 13 Torpedo on display in the World War II Gallery at the National Museum of the United States Air Force. Notably, the fish does not have her “pickle barrel” wooden drop nose attached. (U.S. Air Force photo)
With that being said, the Mark 13 was probably the most common air-dropped anti-ship torpedo in history, with more than 17,000 made, and had the distinction of being the U.S. Navy’s final such weapon used in combat, by Skyraiders from USS Princeton against the Hwachon Dam in Korea. Notably, late-war PT-boats also used the weapon as it was lighter than their older Mark 8s. Some 13-feet long and 22.4-inches in diameter (wider than a tube-launched torp) the Mark 13 weighed about 2,200-pounds, including 600 of Torpex high explosives. Once dropped, it could make 33.5 knots to 6,300 yards.
From “U.S. Naval Weapons” by Norman Friedman via Navweaps:
“A review of war experience showed a total of 1,287 attacks [this count only includes those launched by carrier-borne aircraft, other US Navy aircraft launched another 150 torpedoes – TD], of which 40 percent (514) resulted in hits, including 50 percent hits on battleships and carriers (322 attacks, including Midway), 31 percent on destroyers (179 attacks), and 41 percent (out of 445 attacks) on merchant ships.”
More info on the Mark 13, below:
For the record, the 47th BS inactivated 27 January 1946 at Manila and has remained that way while the parent 41st BG endured into the Cold War as an F-4 unit, the 41st TG, until it was inactivated in 1970 at Incirlik. Ironically, the F-4, a tactical fighter, could carry more ordinance than the B-25 of WWII fame.