Renault NC-31 Light Tank

In 1928 Renault succeeded in his attempt to get his Renault NC accepted as the basis for further light infantry tank development; he was granted an order to build two prototypes. The Army called this project the Char D, Renault used the designation NC28. Of the two prototypes, the first was fitted with the twin machine gun turret of the SRA Char de Bataille prototype. Also a new suspension system was tested incorporating the special chenille légère ("light track") designed by Colonel Balland, which was optimised for high speeds. As this vehicle was a derivative of the NC1, it was later indicated with the designation NC2, creating confusion with the earlier project of that name; mNC3 gun tank, and ordered a pre-series of ten vehicles in December 1929. These had the Renault factory designation NC31, after the intended year of delivery. Renault merely had to build the hulls at a price of 400,000FF each; the cast turrets were, as usual in France, separately ordered with the Schneider company; they were of the ST1 type (Schneider Tourelle 1). As this turret was much wider than the Renault FT turret used on all previous NC models, Renault broadened the hull accordingly; the typical tapering nose point of the Renault FT was abandoned. The ten hulls were delivered between May and November 1931: after an interval of ten years after the delivery of the last Char 2C in 1921, French tank series production for the home market was thus resumed.
any later books assumed they were one and the same vehicle. The Army made a choice in March 1929 for the second prototype, the

The ten pre-series hulls were tested by the 503e Régiment de Chars de Combat. Many shortcomings were discovered by the Commission de Bourges, the French Infantry matériel commission. Steering was difficult, the suspension too weak and the exhaust pipes overheated the engine compartment. Nevertheless the type was accepted for mass production — the commission had little choice in this as the main series had already been ordered — provided that changes were made. The strangely squeezed ST1 turret, the first ten of which were delivered from November 1930, was rejected though as being unacceptably cramped and unbalanced. To prevent that each time the gun was loaded, the breech had to be lowered into the fighting compartment or otherwise the round could not be shoved in, the main armament had been placed in a very forward position. The ST1 turrets were therefore again removed from the first ten vehicles.

Specifications
Weight	14 metric tons
Length	5.76 m
Width	2.16 m
Height	2.40 m
Crew	3
Armor	40 mm
Main armament	47 mm SA34 tank gun
Secondary armament	2x 7.5 mm Reibel machine gun
Engine	Renault V-4 74 hp
Suspension	vertical springs
Operational range	90 km
Speed	18.6 km/h (11.6 mph)

Source : Wikipedia