The Dornier Do X: The world’s largest ‘flying boat’ that could barely get off the ground, 1929-1933

When built in 1929 by the Dornier Company of Germany, the Dornier DO-X was the largest, heaviest and most powerful flying boat in the world.

With a wingspan of 157 feet (48 m) and a length of 130 feet (40 m), the Do X had 12 engines and carried 169 passengers.

First conceived by Claude Dornier in 1924, planning began in late 1925 and was completed in June 1929 after more than 240,000 working hours.

The Do X was a semi-cantilever monoplane and had an all-duralumine hull, with wings made of a steel-reinforced duralumin framework covered in a heavy linen cloth covered with aluminum paint.

It was initially powered by twelve 391 kW (524 hp) Siemens-built Bristol Jupiter radial engines, with six tractor propellers and six pushers mounted on six strut-mounted nacelles above the wing.

The nacelles were attached by an auxiliary wing to stabilize the mounting. The air-cooled Jupiter engines were likely to overheat and could barely lift the DO X to a height of 425 m (1,394 ft).

The engines were managed by a flight engineer, who controlled 12 throttles and supervised 12 sets of gauges. The pilot would request the engineer to adjust the power setting, using an engine order telegraph, similar to a system used on seaplanes.

Many aspects of the aircraft echoed the maritime arrangements of the time, including the flight deck, which bore a strong resemblance to a ship's bridge. After completing 103 flights in 1930, the Do X was refined with the 455 kW (610 hp) Curtiss V-1570 "Winner" water-cooled V-12 engine.

Only then was it able to reach the height of 500 meters (1,600 ft) needed to cross the Atlantic. Dornier designed the flying boat to carry 66 passengers on long-haul flights or 100 passengers on short flights.

The luxurious passenger accommodations were up to the standards of transatlantic liners. There were three decks. The main deck had its own wet bar, a dining saloon and a smoking room with seating for 66 passengers that could also be converted into sleeping berths for night flights.

Behind the passenger spaces was an electro-electric galley, toilet and cargo hold. On the upper deck were the cockpit, shipping office, engine control and radio room.

The lower deck contained fuel tanks and nine waterproof compartments, of which only seven were required to provide full flotation.

A total of three Do X's were built. The original operated by Dornier, and two other machines based on orders from Italy. X2, named Umberto Maddalena (registered I-REDI) and X3, named Alessandro Guidoni (registered I-ABBN). The Italian versions were slightly larger and used a different powerplant and engine mount.

The Flugschiff ("flying ship"), as it was called, was launched on 12 July 1929 for its first test flight with a crew of 14. To satisfy the skeptics, its 70th test flight on October 21 had 169 aboard. It had 150 passengers (mostly production workers and their families, and some journalists), ten aircrew and nine stowaways.

The flight set a new world record for the number of people in a single flight, a record that would stand for 20 years.

The DO X slowly climbed to an altitude of 200 m (660 ft) after a 50-second takeoff run. Passengers were asked to crowd together on one side or the other to help with the turn. It flew for 40 minutes.

To introduce the airliner to the potential United States market, the DO X took off from Friedrichshafen, Germany on 3 November 1930 for a transatlantic test flight to New York under the command of Friedrich Christiansen.

The route took the Do X to the Netherlands, the United Kingdom, France, Spain and Portugal. The voyage was interrupted in Lisbon on 29 November, when a tarpaulin contacted a heated exhaust pipe and caught fire, burning most of the left wing.

After sitting for six weeks in the port of Lisbon, while new parts were fabricated and damage repaired, the flying boat continued with several more accidents and delays along the west coast of Africa and reached the islands of Cape Verde by 5 June 1931. From where it crossed the sea in Brazil and reached Natal.

The flight headed north for the United States via San Juan, reaching New York on 27 August 1931, about ten months after departing Friedrichshafen.

Do X and crew spent the next nine months there as its engines were repaired, and thousands of spectators traveled to Glen Curtis Airport (now LaGuardia) for sightseeing.

The Great Depression dashed Dornier's marketing plans for Do X, and it sailed from New York to Newfoundland and the Azores to Berlin, Berlin, on 21 May 1932, where it arrived on 24 May and was met by an enthusiastic crowd of 200,000. found.