Dornier Do X

Updated: October 2026 – A hull like an ocean liner, above it a gigantic wing carrying twelve engines in a neat row: the Dornier Do X still looks spectacular even in yellowed black-and-white photos. In 1929, it was the largest aircraft in the world, it flew with 169 people on board and made it all the way to New York. You can’t photograph it today – but you can find its traces on Lake Constance, in Berlin and in a replica project that wants to bring the legend back. Here you get history, technology, identifying features and the places where you can still encounter the Do X.

What was the Dornier Do X?

The Do X was a passenger flying boat that contemporaries liked to call a “Flugschiff” (flying ship) – and that fits well. Claude Dornier sketched the idea of a large monoplane flying boat as early as 1924, and the actual design began at the end of 1926. The goal was an aircraft that could carry passengers and mail over long distances at sea, ultimately across the Atlantic. Because the Treaty of Versailles still restricted aircraft building in Germany at the time, the aircraft was built at the Altenrhein plant on the Swiss side of Lake Constance. Much of the money came from the Reich Ministry of Transport. You can find more about the company itself on the page for Dornier.

Construction of the first aircraft began in December 1927 and, according to company figures, consumed around 240,000 working hours. On July 12, 1929, the Do X was launched and briefly lifted off during taxi tests; German sources give July 15, 1929 as the official first flight. It carried the registration D-1929 – the year of its first flight.

Much on board recalled a ship, starting with the commander at the head of the crew. Besides the pilots, a flight engineer flew along who operated the throttles and instruments of the twelve engines from his own station; the navigation and radio rooms were also on the upper deck.

Technology: twelve engines and three decks

The fuselage was built as a boat hull, with a step in the bottom so the aircraft could “tear loose” from the water on takeoff. On the sides sat short sponsons, which Dornier had already used on the Wal: they kept the flying boat stable in the water, replaced floats under the wings and also served as attachment points for the wing struts.

Inside, the space was spread over three levels. At the very top were the cockpit, navigation room, radio room and the flight engineer’s station. The passengers traveled on the main deck: according to descriptions, there was a dining saloon, a smoking saloon with a bar and seats for 66 passengers that could be converted into sleeping berths, plus a galley and toilets. The lower deck held fuel tanks and watertight compartments. For the early 1930s, this was luxury at a level otherwise offered only by zeppelins – how the airships from the same town were built is told in the history of the zeppelins.

The powerplant was the big problem. The first twelve engines were Siemens Jupiter radial engines, air-cooled license-built versions of the Bristol Jupiter with around 500 PS. They tended to overheat and lost power during longer running. In 1930, the Do X was therefore given water-cooled Curtiss Conqueror V12 engines with a good 600 PS each. The two Italian aircraft flew with Fiat engines.

Feature	Do X1 (as of 1930)
Length	40.10 m
Wingspan	48.00 m
Height	10.25 m
Wing area	around 450 m²
Engines	12 × Curtiss Conqueror (previously Siemens Jupiter)
Max. takeoff mass	around 50 t
Cruise speed	around 170 km/h
Range (literature figure)	around 2,800 km

Fully loaded, the Do X reached only low altitudes. For the planned Atlantic route, that was a real risk – and one of the reasons nothing ever came of scheduled service.

The record flight with 169 people

On October 21, 1929, the Do X made aviation history. With 169 people on board, including ten crew members and mostly Dornier employees with their families, it flew over Lake Constance for around 53 minutes. How the passengers were split up exactly is given differently in the literature – some sources also mention stowaways. At that point, it did not yet have an approval for passenger flights at all. The record for the most people on board an aircraft stood for around 20 years.

The pictures from that day went around the world and made the Do X famous overnight. In October 1930, it then received official acceptance from the German Aviation Research Institute (Deutsche Versuchsanstalt für Luftfahrt).

The great publicity flight to America

To win buyers, Dornier sent the Do X on a goodwill tour that was more like an odyssey.

The Do X had wintered at the then Glenn Curtiss Airport in Queens, the site of today’s LaGuardia Airport. Anyone standing in Planeview Park at LaGuardia Airport today is therefore spotting on historic ground. On board the return flight, by the way, was also the pilot Antonie Strassmann.

After the return, more visiting flights to German cities followed. On May 9, 1933, the Do X touched down too hard when landing on a Danube reservoir near Passau, and the tail broke off. The aircraft was repaired, but passenger service was history.

Do X2 and Do X3: the Italian sisters

In 1931, the Italian company SANA ordered two aircraft for Mediterranean service. They were named “Umberto Maddalena” (I-REDI) and “Alessandro Guidoni” (I-ABBN) and flew with Fiat engines in streamlined cowled nacelles. The planned scheduled service never happened. Instead, the Italian military used the two flying ships for training flights and ceremonial duties. The Do X2 was retired in 1935 after several mishaps, and in 1937 both were scrapped.

Aircraft	Registration	Engines	Fate
Do X1	D-1929	Siemens Jupiter, later Curtiss Conqueror	Destroyed in Berlin in 1943
Do X2 “Umberto Maddalena”	I-REDI	Fiat	Scrapped in 1937
Do X3 “Alessandro Guidoni”	I-ABBN	Fiat	Scrapped in 1937

How to recognize the Do X in photos and models

You will never see a flying Do X. But in historical photographs, postcards, stamps or as a model in a museum, you often come across it – and then a trained eye helps you tell it from other flying boats of the time.

Whether it is an early version or a conversion is revealed by the nacelles: with the Siemens engines, the powerplants stood fairly exposed on frameworks; after the switch to Curtiss engines, the nacelles look longer and more enclosed. The guide Identifying vintage aircraft in the sky offers more tricks for vintage aircraft.

Size comparison: Do X, Spruce Goose and today

The Do X was eventually overtaken in its role as the largest aircraft – a later giant is especially famous, the Hughes H-4 “Spruce Goose”, whose story is told in the article Hughes H-4 Hercules. The comparison with today’s aircraft is interesting: at 48 meters of wingspan, the Do X was wider than an A320 or Boeing 737, while its takeoff mass was well below theirs. It used the space mainly for wings, engines and fuel – not for payload.

This very ratio shows why flying boats of this size hit limits in the 1930s. More powerful engines and later land-based aircraft with fixed runways took over long-distance service.

What became of the Do X

In 1933, the Do X1 came to Berlin and was displayed in the German Aviation Collection, a predecessor of today’s German Museum of Technology in Berlin. It was badly damaged in an air raid in November 1943, and after the war the remains largely disappeared. Today only individual parts survive:

• Dornier Museum Friedrichshafen: parts of the tail broken off at Passau in 1933 and a spar profile
• German Museum of Technology in Berlin: a few metal parts
• Friesen Museum on Föhr: a wooden propeller, because Commander Christiansen came from the island

The Dornier Museum Friedrichshafen sits right next to Friedrichshafen Airport. There is no complete Do X replica there; the flying boat era is represented by the 1:1 replicas of the Merkur and Wal, with the Do X part of the company history in the exhibition. Just a few minutes away, the Zeppelin Museum Friedrichshafen tells the story of the airships, from whose circle Claude Dornier came.

The museum replica: a flying ship is being rebuilt

Since 2014, the German Freundes- und Förderkreis Do X e.V. (Friends and Supporters of the Do X), chaired by Peter Kielhorn, has been working on a static, walk-through reconstruction at 1:1 scale. Students of the Baden-Württemberg Cooperative State University (campuses in Friedrichshafen, Mosbach and Lörrach) have helped with the reconstruction. The templates are historical photos and documents as well as surviving original components – including loans from a collection in Turin, which were laser-scanned in 2022.

Whether and where the replica will be permanently displayed is open as of October 2026. According to press reports, the association is in regular contact with the management of the Dornier Museum. If you want to experience the project live, you have good chances at the aviation trade show in Friedrichshafen – what awaits you there is covered in the article AERO Friedrichshafen. How you can get involved in such projects yourself is shown in Volunteering at aviation museums.

A flyable 1:8-scale model with a wingspan of around six meters was built by model aviators from the region as early as 1998 for an air show on Lake Constance; according to reference works, it is housed at the Altenrhein aviation museum. The airfield where the Do X was once built is described in the spot entry Altenrhein Aviation Museum on Lake Constance.

Your Do X tour on Lake Constance

With Planetrack, you put the Do X on your wish list and post photos of original parts and the replica with aircraft type, place and spot. In your hangar, you then see at a glance what you have already collected. Other Dornier types you can find on Lake Constance are the Do 27 and the Dornier 228. The magazine article Dornier Do X delivers the detailed story of the flying ship.

Conclusion

The Do X was ahead of its time – and at the same time too early. Twelve engines, three decks and a record flight with 169 people made it a sensation, while weak engines and low altitude prevented success in scheduled service. No aircraft has survived, but tail remnants, propellers and a replica in the making keep the legend alive.