Dornier Do X flying boat over New York in 1931

Dornier Do X: The Swiss-Built Flying Boat That Was the Jumbo of 1929

by Max Grünwald | Oct 11, 2026 | Geschichte & Legenden | 0 comments

In a glass case at the Swiss Museum of Transport in Lucerne sits a model of a flying boat with twelve engines mounted in pairs above its wing. The placard beside it calls the Dornier Do X the “Jumbo der 1930er-Jahre”, the jumbo of the 1930s. It was built not in Germany but on the Swiss shore of Lake Constance, and in November 1932 it even landed on Lake Zurich.

The placard gets the big picture right. A few of its numbers need a closer look, and one of its conclusions about ocean flying is too simple.

Kurzinfo

Bauherr: Dornier, at Altenrhein (canton of St. Gallen), Switzerland
Erster Flug: 12 July 1929
Motoren: 12 in push-pull pairs: Siemens-built Bristol Jupiter, later Curtiss Conqueror
Spannweite: 47.8 m; length 40.05 m
Gewicht: About 28 t empty, up to about 56 t maximum
Reisegeschwindigkeit: About 170–175 km/h
Passagiere: 66 on long flights; 169 people carried on 21 October 1929
Gebaut: 3: the Do X1 and two for Italy (X2 and X3)

Why a German Giant Was Built in Switzerland

Claude Dornier designed the Do X in Friedrichshafen, but the Treaty of Versailles still restricted aircraft building in Germany. So Dornier built it at a purpose-built plant in Altenrhein, across Lake Constance in Switzerland. It flew there for the first time on 12 July 1929, and by most accounts it lifted off by accident during what was planned as a taxi test.

“Die Dornier Do-X war das grösste Flugzeug der Welt und der Inbegriff des technischen Fortschritts.”

Swiss Museum of Transport — placard “Jumbo der 1930er-Jahre” (“The Dornier Do X was the largest aircraft in the world and the epitome of technical progress.”)

“Largest aircraft in the world” is fair for its time. In 1929 the Do X was the largest, heaviest and most powerful flying boat ever built. It kept that title until 1934, when the Soviet Tupolev ANT-20 “Maxim Gorky” flew with a 63-metre wingspan, although the Do X remained heavier.

Dornier Do X in flight over Lake Constance in 1929 — The Do X in flight over Lake Constance in 1929. Photo: Agence Meurisse / Bibliothèque nationale de France, public domain

169 People in One Aircraft

The placard says the Do X was designed for about 70 passengers and once carried 169. On long flights it was laid out for 66 passengers, so “about 70” is a rounding. The 169 figure is right, but it counts everyone aboard, not just passengers. On 21 October 1929, on a flight of around 40 minutes over Lake Constance, the Do X carried 169 people: 150 passengers, 10 crew and, by most accounts, nine stowaways. The record for the most people carried in one aircraft stood for about 20 years.

The Long Tour to New York

From November 1930 the Do X set off on a demonstration tour that turned into an epic. It flew via the Netherlands, England, France and Spain to Lisbon, where a fire on 29 November 1930 damaged a wing and kept it there for about six weeks. It continued via the Canary and Cape Verde Islands, crossed to Natal in Brazil on 5 June 1931, and reached New York on 27 August 1931, around ten months after leaving. It stayed there for about nine months, left on 21 May 1932 and landed on the Müggelsee in Berlin on 24 May 1932 in front of some 200,000 spectators.

Dornier Do X flying boat over the Atlantic in 1932 — The Do X over the Atlantic on its return from America in May 1932. Photo: Bundesarchiv, Bild 102-13510 / CC BY-SA 3.0 DE

Lake Zurich, November 1932

After a tour of German cities from June 1932, the Do X ended its season on Lake Zurich on 2 November 1932, as the placard says. About two weeks later it flew back to Altenrhein for its winter overhaul. In 1933 it was handed to Luft Hansa, damaged its tail in a landing near Passau that May, and from 1934 was displayed in an aviation museum in Berlin, where it was destroyed in an RAF bombing raid in November 1943. The two Italian Do Xs were scrapped at La Spezia in 1937. Fragments of the original survive at the Dornier Museum in Friedrichshafen, and a full-size static replica is under construction for the type’s centenary in 2029.

Did Landplanes Win the Ocean?

The placard closes by saying that landplanes, not flying boats, later made the breakthrough over the oceans. That is true in the long run but skips a whole chapter. The first scheduled transatlantic passenger service was flown by a flying boat, Pan Am’s Boeing 314, in June 1939. Landplanes such as the Douglas DC-4 and Lockheed Constellation only took over after 1945. The Do X itself was too slow and too heavy for regular service, but flying boats had their decade.

“… stellten Bau und Einsatz dieses Riesenflugbootes eine Pioniertat ersten Ranges dar.”

Swiss Museum of Transport — placard “Jumbo der 1930er-Jahre” (“… building and operating this giant flying boat was a pioneering achievement of the first order.”)

Placard Check

Right: built at Altenrhein, 169 people on one flight in 1929, demonstration flights across Europe and to South and North America, and a landing on Lake Zurich in 1932. Generous: “largest aircraft in the world” (true from 1929 to 1934) and “about 70 passengers” (66 on long flights). Too simple: the claim that landplanes made the ocean breakthrough, when flying boats opened scheduled transatlantic service in 1939. The museum’s online collection page also gives the first flight as 13 July 1929; most sources say 12 July.

Sources: Swiss Museum of Transport (placard and collection item VHS-4165); Wikipedia, Dornier Do X and Tupolev ANT-20; Flug Revue, “Dornier Do X: Der erste Jumbo”; HistoryLink (Pan Am Boeing 314); Schwäbische Zeitung and Do-X-Vision (replica project); Bundesarchiv; Bibliothèque nationale de France; US Navy / San Diego Air & Space Museum

Häufig gestellte Fragen

Where was the Dornier Do X built?

The Dornier Do X was built at Altenrhein in the Swiss canton of St. Gallen, on the shore of Lake Constance, because the Treaty of Versailles restricted aircraft construction in Germany. It was designed by Claude Dornier in Friedrichshafen and first flew at Altenrhein on 12 July 1929.

How many passengers did the Dornier Do X carry?

The Dornier Do X was laid out for 66 passengers on long flights. On 21 October 1929 it carried 169 people over Lake Constance, usually given as 150 passengers, 10 crew and nine stowaways, a record that stood for about 20 years.

Was the Dornier Do X the largest aircraft in the world?

Yes, in 1929 the Dornier Do X was the largest, heaviest and most powerful flying boat built. The Soviet Tupolev ANT-20 overtook it in wingspan in 1934 with 63 metres against the Do X’s 47.8, although the Do X remained heavier.

Did the Dornier Do X land on Lake Zurich?

Yes. After a tour of German cities, the Dornier Do X landed on Lake Zurich on 2 November 1932 and about two weeks later flew back to Altenrhein for its winter overhaul.

How fast was the Dornier Do X?

The Dornier Do X cruised at about 170 to 175 km/h and had a top speed of about 242 km/h. Its slow speed and weight, together with a fire in Lisbon, helped stretch its flight to New York to around ten months in 1930 and 1931.

What happened to the Dornier Do X?

The original Dornier Do X went to Luft Hansa in 1933 and from 1934 was displayed in a Berlin aviation museum, where it was destroyed in an RAF bombing raid in November 1943. The two Italian examples were scrapped in 1937, and a full-size replica is being built for the centenary in 2029.