Type 4 Ka-Tsu

Type 4 Ka-Tsu
A Ka-Tsu on display
Type	Amphibious armored personnel carrier
Place of origin	Empire of Japan
Production history
Designed	1942–1943
No. built	49[1]
Specifications
Mass	16 tons[1]
Length	11 m
Width	4 m
Height	2.25 m
Crew	5
Armor	10 mm[1]
Main armament	2x torpedoes[2]
Secondary armament	2x 13 mm machine guns[1]
Engine	gasoline (petrol) in a water-tight pressure box 62 HP
Power/weight	3 HP/1 ton
Suspension	-
Operational range	-
Maximum speed	(sea) 5 knots

The special Type 4 Launch Ka-Tsu (特四式内火艇 カツ, toku-yon-shiki uchibitei Ka-Tsu) was a Japanese amphibious landing craft of World War II. The first prototype was completed in late 1943 and trials were conducted off Kure in March 1944.

History

Japan's combat experience in the Solomon Islands in 1942, which revealed the difficulty of resupplying Japanese forces in such situations, prompted the IJN to commence an amphibious tractor program in 1943, as the Ka-Tsu.^[3]

Design

The Ka-Tsu's primary purpose was to transport cargo and/or troops ashore.^[2] It had light armored shielding with a maximum of 10 mm.^[1] Its engine compartment and electric final drives were hermetically sealed, as it was intended to be launched from a submarine.^[3] The twin drive propeller shafts were designed to retract "into their ducts" once the vehicle reached the beach.^[2]

The first prototype was completed in late 1943 and trials were conducted off Kure in March 1944.^[3] By the time development had been completed, it was proposed that the Ka-Tsu be used to attack US battleships anchored in atolls (such as Ulithi), which could not readily be attacked using conventional means. It was proposed that a Ka-Tsu armed with a pair of naval Type 93 torpedoes^[4] be dropped off by submarine away from the atoll, propel itself to the outer reef using its tracks, and then enter the lagoon on the inside of the reef.^[3] Tests were successfully carried out with a modified Ka-Tsu carrying two torpedoes on its deck.^[3] A total of 49 units were produced.^[1]

Operation Tatsumaki

In May 1944, the submarines I-36, I-38, I-41, I-44 and I-53 and the auxiliary submarine tender Tsukushi Maru began training in the Seto Inland Sea off Nasakejima for Operation Tatsumaki ("Tornado"), which called for the submarines to transport modified Ka-Tsu's, each armed with two torpedoes, from Kure to Majuro.^[5][6] After the submarines launched the Ka-Tsu's, the operation called for the tracked vehicles to proceed to shore, moving overland across the atoll's, then enter the water of the lagoon and attack Allied ships with the torpedoes.^[5][6] Operation Tatsumaki was thereafter postponed pending the correction of defects found in the modified Ka-Tsu vehicles.^[7] The war ended before any such mission could be mounted and the Ka-Tsu deployed in combat.^[3]

Gallery

• 
  Type 4 Ka-Tsu with machine guns mounted
• 
  Rear-side angle view of Type 4 Ka-Tsu
• 
  Two Type 4 Ka-Tsu with torpedoes on the deck of a IJN submarine

See also

• Blockade Runner
• Type 3 submergence transport vehicle
• Ha-101 class submarine

Notes

1. Taki's Imperial Japanese Army: Type 4 Amphibious Vehicle "Ka-Tsu"
2. Tomczyk 2003, p. 33.
3. Zaloga 2007, p. 24.
4. Tomczyk 2003, pp. 33, 37.
5. Hackett, Bob; Kingsepp, Sander (2014). "IJN Submarine I-44: Tabular Record of Movement". combinedfleet.com. Retrieved 15 September 2020.
6. Hackett, Bob; Kingsepp, Sander (2019). "IJN Submarine I-53: Tabular Record of Movement". combinedfleet.com. Retrieved 15 September 2020.
7. Hackett, Bob; Kingsepp, Sander (2019). "IJN Submarine I-36: Tabular Record of Movement". combinedfleet.com. Retrieved 15 September 2020.

References

• Tomczyk, Andrzej (2003). Japanese Armor Vol. 3. AJ Press. ISBN 978-8372371287.
• Zaloga, Steven J. (2007). Japanese Tanks 1939–45. Osprey Publishing. ISBN 978-1-8460-3091-8.

External links

• Taki's Imperial Japanese Army Page - Akira Takizawa