 The Dornier Do X was the largest, heaviest, and most powerful flying boat in the world when it flew in 1929, having a similar span of 48 m (157 ft 6 in) and a maximum takeoff weight of 56,000 kg (123,459 lb).During the years between the two World Wars, only the Soviet Tupolev ANT-20 "Maxim Gorki" landplane of 1934 was larger at 63.00 m (206 ft 9 in) span, but at 53 metric tons maximum takeoff weight it was not as heavy as the Do X's 56 tonnes.The largest airship ever built was the Zeppelin LZ 129 "Hindenburg".