Osorio T-1

The Engesa EE-T1 Osório was a Brazilian main battle tank prototype developed by Engesa between 1982 and 1986. The project was intended to produce a vehicle for export to Arab and Third World countries, with the goal of using export revenue to fund later production for the Brazilian Army. Development was initially privately funded by Engesa, but the Brazilian National Development Bank provided a loan in 1987 to address cashflow issues within the program. Two prototypes were completed by 1986. While the tank was considered by Algeria, Iraq, Libya, and Saudi Arabia, the lack of finalized orders and the end of the Cold War led to the project's termination. The program was officially scrapped following Engesa's 1993 bankruptcy filing and the subsequent collapse of the Brazilian armored vehicle industry in the late 1990s.

The EE-T1 was designed for a four-man crew consisting of a commander, gunner, loader, and driver. Its protection consisted of composite armor incorporating aluminum, steel, carbon fibers, and ceramics. Two distinct armament configurations were produced: the P1 prototype was equipped with a 105 mm L7 rifled gun, while the P2 prototype featured a 120 mm Giat Industries G1 smoothbore gun. Secondary armament for both versions included two 12.7 mm M2HB machine guns, with one mounted coaxially and the other on the roof. The vehicle was powered by a 12-cylinder MWM TBD 234 Diesel engine paired with a ZF Friedrichshafen LSG 3000 transmission and a hydropneumatic suspension system. Although intended to be cost-effective through the use of domestic components, the design utilized imported parts, including the turret and transmission.

The Osório never entered serial production or saw combat. Following the cancellation of the project, pre-series components were returned to manufacturers to recoup financial losses. The two existing prototypes were stored at the São Paulo War Arsenal in Barueri until March 2003, when they were officially assigned to the 13th Mechanized Cavalry Regiment in Pirassununga. The vehicles remained in limited service with the regiment until 2013. The 105 mm prototype is currently on display at the Military Museum Conde de Linhares, and the 120 mm prototype is located at the Armored Instruction Center in Rio de Janeiro.