Type 4 Ka-Tsu
The Ka Tsu was developed by the Imperial Japanese Navy to give it a ship–to–shore capability similar to that provided by the USA’s LVTs. Introduced in 1944, the 16-ton vehicle could carry up to 40 troops or four tons of cargo, plus a crew of five. Access to the cargo area was via six hatches in the top deck, so it was unable to carry vehicles or large artillery pieces. It was armed with two pedestal–mounted Type 93 13mm machine guns. Propulsion in the water was via two propellers which gave it a top speed of 5 knots.
Special Type 4 floating tank (Katsu car) was a vehicle whose character was largely different from that of other floating tanks developed by the Japanese Navy, and is not a so-called amphibious tank, but is developed mainly for the transportation of personnel and supplies in island areas. It is an amphibious transport vehicle. The vehicle was expected to launch from the submarine and transport supplies directly to the inland area. This is a war against Gudarkanal in 1942-43, etc., while being successfully transported on the coast, it could not be transported to the inland area, and received war training that lost many of the landing materials by air raids and gunfire.
Since this vehicle, which was developed by Mitsubishi Heavy Industries under the secret name "Katsu vehicle", is premised on transportation by a submarine like other floating tanks, the engine and electrical system are with special floating tanks (Ka-Mi vehicles) Likewise, it was designed to be mounted on the vehicle body after surfacing.
The special Type-4 boat used the Japanese 95-type heavy-duty tank chassis, which made it the only amphibious tank capable of carrying torpedo weapons, but, with insufficient power, it could climb no faster than a tortoise in actual use after carrying torpedoes.
The vehicle could carry torpedoes one by one to the left and right on the deck, and these two torpedoes were the main armament of this vehicle. About torpedoes to be mounted vary according to document, and there are documents which assume 45cm torpedoes and documents which assume eight-year type torpedoes (aperture 61cm). In any case, it was said that the Ka-Tsu was able to launch the torpedo without problems in the launch test.
As a secondary arm, two 93-type 13mm machine guns were equipped on the deck. The 93-type 13-mm machine gun was a domesticated 13.2 mm ochikis M1 929 machine gun introduced by the Japanese Navy from France, and was manufactured at the Yokosuka Naval Factory. In the case of using the Type-II armor-piercing bullet, it was possible to penetrate a 12 mm uniform rolling armor plate with an initial velocity of 800 m / sec. The maximum range was 6,000m, and the bullet system was a 30-shot clip system.
Since the vehcile was originally developed for transportation of personnel and goods, armor defense ability was poor compared with other floating tanks developed for combat. Even with the thickest front of the vehicle, the armor thickness was only 10 mm, and because the vehicle body was made of mild steel instead of bulletproof steel, even bullets could easily be penetrated if shot.
However, while other floating tanks were equipped with floats for floatation at the front and back of the vehicle body to obtain buoyancy, the Ka-Tsu had sufficient buoyancy as the vehicle body itself like the LVT of the US Army. It did not need floats. While other floating tanks were unable to sail on the water again because they would discard the float after landing, the Ka-Tsu could reciprocate between the sea and the land any number of times.
By the way, the loading capacity of the was 40 people or 4t of cargo. The engine mounted on the motor-driven katsuka was the same A6120VDe in-line 6-cylinder air-cooled diesel engine (power 120hp) made by Mitsubishi Heavy Industries, which is the same as the kami-ka, and the same shift and steering machine as the kami-ka was used. In addition, it was equipped with a distributor that switched the powertrain to the actuating wheel on the front of the vehicle body or a screw provided on the rear panel of the vehicle body as well as the razor.
When sailing on the water, power to the track was cut off, and two screws were rotated by two shafts passing from the distributor to both sides of the engine. The distributor also played the role of a bilge pump that drains water into the vehicle. The suspension system of the Ka-Tsu uses the same seesaw system as the camber, and the suspension mechanism consisting of the horizontal coil spring and the link arm was housed inside the vehicle body in consideration of the water tightness and the bulletproof effect.
However, since the body was significantly extended compared to the base design, two sets of suspension are mounted on one side, and the number of rolling wheels is doubled to eight on one side and four on the upper support wheel. It was The weight of the katsu was greatly increased compared to the kami because the body was extended significantly. However, the weight of the Ka-Tsu was greatly reduced as the engine was equipped with the same one. The maximum speed on the road of the cut-off vehicle remained at 20 km / h, and on land it was only possible to deliver about half the speed of the Ka-Mi.
The basic design is said to have been drafted by the navy's Horimoto shipbuilder, but his recollections are that the prototype was completed several months after the design was made in the safe of the navy factory. The design may have been entrusted to Mitsubishi. The reason why the period from the completion of the basic design of the vehicle to the actual completion of the prototype was surprisingly short. Contrary to the concept of the amphibious transport vehicle at the beginning of development, it was equipped with torpedoes. The vehicle was mass-produced at Mitsubishi Heavy Industries' Tokyo Equipment Works, just like any other in-house boat.
The Japanese commissioned Mitsubishi Heavy Industries in Tokyo to start trial of the amphibious chariot, and by March 1944, 3 prototypes had been completed, named special Type-4 inner-fire boats.
It was planned to cut off the loading capacity to the submarine in the middle of production, and shift production to “2 type” corresponding to the increase of loading capacity and liquid fuel transportation, along with that, the conventional type It came to be called "one type". As of January 1945, the cut-off vehicles to be procured from the same month were basically planned to be two types, but it is doubtful that there were two types of unit deployment because production was delayed in practice.
Although 18 vehicles were produced in this vehicle, there is also a document that here were finally produced nearly 50 vehicles. Only one of the 49 Type 4s produced has survived, and until a few years ago it was on display as part the amphibious tractor collection at the USMC’s Camp Pendleton, California. It was stored in the open air at the Marine Corps Logistics Base at Barstow, California. It does not appear to have been modified to carry torpedoes.
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