In the early 20th century, the most powerful flying boat in the world soared into the sky.

The Do X, manufactured by the German company Dornier, was the world’s largest, heaviest, and most powerful flying boat when it was introduced in 1929. Aircraft designer Claude Dornier, founder of the German company Dornier, conceived the Do X in late 1925. After more than 240,000 hours of work, the flying boat was completed in June 1929. It was a monoplane with a fuselage made entirely of duralumin, and wings made of steel-reinforced duralumin, covered with thick linen and coated with aluminum paint. The aircraft was 40 m long and had a wingspan of 48 m.

The Do X was initially powered by 12 391 kW Bristol Jupiter engines. However, they were prone to overheating and could barely get the Do X to its 425 m altitude. The engines were controlled by a flight engineer. The pilot would relay commands to the engineer to adjust power in a similar way to the systems on ships using voice commands. Many features of the Do X reflected the naval designs of the time, including a cockpit that looked very much like a ship’s cockpit.

After completing 103 flights, in 1930, the Do X was re-equipped with a Curtiss V-1570 Conqueror engine with a capacity of 455 kW. Thanks to this, it can reach the 500 m altitude needed to cross the Atlantic Ocean. Do X’s luxurious space for passengers approaches the standards of transatlantic ships. The ship has three decks. On the main deck is a smoking room with a private bar, dining room, seating for 66 passengers that can be converted into beds for night flights. At the end of the passenger space is the kitchen, toilet, and cargo compartment. The cockpit, navigation room, engine control room, and radio room were located on the upper deck. Meanwhile, the lower deck contains fuel tanks and 9 watertight compartments, only 7 of which are enough to keep the flying boat completely afloat.

Do X made its first test flight on July 12, 1929, with a crew of 14 people. During the 70th test flight on October 21, there were 169 people on the plane, of which 150 were passengers (mainly workers and their families and some journalists), 10 were crew members, and 9 stowaways. The flight set a new world record for the number of people carried on a single flight. This record stood for 20 years. After a 50-second run-up, the Do X gradually climbed to a height of 200 meters. Passengers were asked to gather on one side or the other to help the plane turn. It flew for about 40 minutes.

To impress the potential American market, the Do X took off from Friedrichshafen, Germany, on November 3, 1930, under the command of Friedrich Christiansen for a transatlantic test flight to New York. The journey took the aircraft to the Netherlands, England, France, Spain, and Portugal, but was interrupted in Lisbon on November 29, when a tarpaulin came into contact with a hot exhaust pipe and caught fire, burning off much of the left wing. The Do X continued its journey to New York, finally reaching the city on August 27, 1931. It spent nine months in New York for engine maintenance before returning to Berlin.

The Great Depression of 1929 – 1933 negatively affected Dornier’s marketing plans for Do X. The plane left New York on May 21, 1932, via Newfoundland and the Azores to Müggelsee, Berlin. It landed in Berlin on May 24 and was greeted by a crowd of 200,000 people. Do X was transferred to German national airline Lufthansa after Dornier ran into financial difficulties and was unable to continue operating the flying boat. After a successful flight to German coastal cities in 1932, Lufthansa planned for the Do X to be used in regular transatlantic passenger service. However, during an unfortunate landing in a lake near Passau, the flying boat was torn apart.

Do X became an exhibit until it was destroyed during World War II. Fragments of the torn tail are on display at the Dornier Museum in Friedrichshafen. Although not commercially successful, the Do X once set a world record by carrying 169 passengers on a single flight.