This flew in 1952, and by the end of the year was followed by the 451M (Mlazni – "Jet") which had conventional seating for the pilot and in place of the two Walter Minor 6-III inline engines of the original Ikarus 451 (which has two inverted Walter six-cylinder piston engines of 160 horsepower each, 6.7 m (22 ft) wingspan, a maximum speed of 335 km/h (182 knots) and a ceiling of 4750m (15,570 ft).)