Sumida AMP

The Sumida AMP ("AMP" for amphibious) was an experimental amphibious armoured car developed for the Japanese army's cavalry. It was built in 1931 by Ishikawajima, whose earlier company name was Sumida, and tested in 1932.

Background

In the years after the First World War, the Japanese cavalry looked at armoured cars as a way to mechanise. Wheeled cars did badly on China's poor roads, so the cavalry turned to tracked and amphibious designs, starting with this one.

Design

The AMP was based on the Citroën-Kégresse half-track layout, in the same way as the British Crossley-Martel. It had a boat-shaped hull, rear-mounted tracks and wheels at the front. On land it was steered by its wheels, and afloat by propellers mounted next to them. According to one Japanese account it ran in the opposite direction in the water to the one it used on land. George Forty's Photo History of Armoured Cars gives a weight of 2.5 tonnes, 5 mm armour, 45 km/h on the road and 9 km/h in the water.

Outcome

The AMP did better afloat than expected, but its engine was troublesome and its cross-country performance poor, so it was dropped. The cavalry tried other amphibious cars and then gave up the idea, ordering the land-only Type 92 combat car from Ishikawajima instead (finished 1932). A small number of amphibious Type 92s followed.

Later Japanese amphibians

The archive's overview of Japanese amphibious armour follows the line further. It covers Mitsubishi's float-equipped SR-I (1933-34, one built), the boat-hulled SR-II from Ishikawajima (a small pilot batch), and the SR-III with a 13.2 mm machine gun, after which the army passed the work to the navy. Then came the navy's Type 2 Ka-Mi amphibious tank, with detachable front and rear pontoons, in production from 1941 and used on Saipan, Rabaul and Leyte. Last were the Type 3 Ka-Chi (about 20 built), the Type 4 Ka-Tsu armoured amphibious transport (about 100 built, some carried by submarine) and the unbuilt Type 5 To-Ku.