The pilots were especially bothered by the unusually high landing speed, resulting from the high surface load exceeding 170 kg/m2 and nobody was impressed by the maximum speed of 550 km/h, which did not match the designers' calculations. Improved performance was expected for the second and third prototypes with an enlarged wing area, a modified engine cowling and structural modifications aimed at overall lightness. While the first and second prototypes were armed with two 12.7 mm Ho-103 machine guns mounted above the engine and two 20 mm Mauser MG 151 guns in the wing, the third prototype carried two Ho-103 machine guns instead of two wing guns.
