At the time of the evacuation of the Sukhoi OKB to Novosibirsk, the prototype of a developed version of the Su-1, the Su-3, was under construction. Initiated under the designation I-360, the Su-3 mated the Su-1 fuselage and tail surfaces with an entirely new wing of revised profile with shorter-span outer panels resulting in a 2.00m² reduction in wing area. The radiator bath was enlarged, but in all other major respects the Su-3 was similar to the Su-1. Retaining the M-105P engine and the same armament, the Su-3 was completed at Novosibirsk and entered flight test in the late summer of 1942. Although the TsIAM had meanwhile undertaken much development work on the TK-2 turbo-supercharger, the principal defects were found to remain, and, as a consequence, development of the Su-3 was discontinued towards the end of 1942.