The Dornier Do X, the first example built in 1929, was the largest flying boat in the world when it was produced. Its maximum take-off weight was 56 metric tons, length 40m, wingspan 48m and height 10.25m. On the test flight in October 1929, it carried 169 people on board; a record that was not broken for another 20 years. It was powered by twelve engines (six tractor propellers and six pushers) mounted on the wing.
The Do X was built in a plant by Lake Constance at Altenrhein (Switzerland), because the Treaty of Versailles forbade such large and powerful aircraft to be built in Germany. It was intended for luxurious travel, with passenger accommodation approaching the standards of trans-Atlantic liners. Only three examples were built, because of a lack of commercial interest, caused by the Great Depression and numerous non-fatal accidents.
A trans-Atlantic flight to New York, to introduce the aircraft to the potential USA market, began on 3rd November, 1930, when the Do X took off from Friedrichshafen, Germany. The Do X made several stops in the Netherlands, England, France, Spain and Portugal.
On 29th November, the aircraft was damaged by a fire that broke out on board. The journey had to be interrupted in Lisbon for six weeks, whilst the necessary repairs were carried out.
The Do X then continued its journey along the western coast of Africa to Cape Verde, with several other accidents and delays. It crossed the Atlantic Ocean and landed in Rio de Janeiro, Brazil, on 20th June, 1931. The flight continued along the Atlantic coast of South America, with numerous stops in various towns; then across the Caribbean to the USA, finally reaching New York on 27th August, 1931. The journey took almost nine months!
The return to Germany was again delayed by necessary repairs. The Do X departed from New York on 21st May, 1932, flying via Newfoundland and the Azores, and arriving to Berlin on 24th May, 1932.
The Do X subsequently flew in Europe, but its last flight occurred in September 1933. The other two produced examples were used by the Italian Air Force.