The VI-100 project was an ambitious one for its time, with advanced features such as a pressurised cabin, all-metal construction, turbo-superchargers, and many electrically actuated systems. In addition, the performance requirements were also quite demanding: it was to be capable of reaching 630 km/h at an altitude of 10,000 m, a ceiling of 12,500 m, and a range of 1,400 km. The aircraft would also need a reinforced structure in order to withstand the Mach stresses of making diving attacks from high altitude against enemy bomber formations. In order to assist with the challenging development of the "100", other OKBs such as those of Yakovlev, Mikoyan & Gurevich, and Sukhoi were also enlisted. The first full-scale VI-100 mock-up was completed in May 1939, and the first flight of the prototype occurred on 22 December 1939.