The last of the "A" series high-altitude fighter prototypes to enter flight test, the I-224 was flown for the first time on 20 October 1944. Powered by a Mikulin AM-39B engine rated at 1750hp for take-off, driving an 3.50m diameter propeller with 40cm chord "paddle" blades, and equipped with a single TK-300B turbo-supercharger on the starboard side, the I-224 carried an armament of two synchronised 20mm ShVAK cannon. An unusual feature of the I-224 was its exhaust system which included four fixed aft-facing ejection "chimneys". The I-224 achieved an altitude of 14,100m during its brief flight test programme which reportedly terminated when a malfunctioning supercharger resulted in an uncontrollable engine fire.