Jetrader - Spring 2017 - 41

aviation history

The Dornier Do X
By Jack Feir, ISTAT Member Emeritus

Photo: German National Archive via Wikimedia Commons.

Claude Dornier
During the 1920s, Claude Dornier and his company Dornier GmbH
earned a well-regarded reputation for developing a variety of
aircraft, including land planes and sea planes, some with single
engines and some with two or more engines.
During that time, to comply with the restrictions of the Treaty
of Versailles after World War I that curtailed the manufacture of
aircraft in Germany, Dornier built his aircraft outside Germany and
licensed his designs to be manufactured in Italy, Spain, Japan and
the Netherlands. Later, when the Nazi government came to power,
the treaty's restrictions were abandoned, and some production
took place in Germany.
Dornier's model designations initially were simply single letters of
the alphabet, beginning with the Dornier Do A in 1921, up through
Do B, Do C and so on until the alphabet was nearly exhausted at
X. In fact, one of his most famous efforts was the Dornier Do X,
begun in 1925 and first flown in 1929. It was a huge flying boat,
almost entirely made of metal, larger and heavier than any other
aircraft in the world at that time.

number of paying passengers. As such, the Do X was intended to
carry about 65 passengers in grand style, with 16 to 20 crewmembers manning the ship.
For propulsion, the first Do X was fitted with 12 (yes, 12!) 9-cylinder Bristol Jupiter radial, air-cooled engines rated at 524 horsepower
each, mounted in push-pull pairs on the front and rear of pylons
above the top of the wing. Despite having about 6,300 total horsepower, the Do X was under-powered. Moreover, the pusher engines
on the aft end of the pylons did not receive much cooling slipstream
and tended to overheat and could not be trusted to run very long
at full power.
Flight testing showed that the aircraft could barely reach an altitude of 1,400 feet. However, in 1930, after about 100 flights, it was
refitted with more powerful 610 hp Curtiss Conqueror water-cooled
V−12 engines. While the new engines were more powerful, they were
also much heavier, so overall the aircraft was still under-powered.
With inefficient fixed-pitch wooden propellers and no wing flaps to
create more lift, it needed a long run to take off, and it cruised at
a sedate airspeed of about 110 miles per hour while the 12 engines
were burning prodigious amounts of fuel.

Inside the Do X
The interior of the Do X was divided into three levels. Like a
grand ship, the top level was a wheelhouse for two pilots near the
front, followed by a navigation and communication area. Further
aft, under the wing, was the engine control room where the engineer's panel included six throttles and instrumentation on the port
side of the compartment and six more throttles and instruments
on the starboard side.
The second level accommodated the passengers, with the space
divided into 11 rooms. Amenities included a lounge, a smoking room,
coat closets, two toilets and washrooms and an electric kitchen
where meals were served on special porcelain dinnerware and fine
linen tablecloths. This was at a time when airline passengers were
primarily celebrities and the upper class, and ticket prices could

The Dornier Do X
The Do X was manufactured at Dornier's factory in Switzerland,
located on the shore of Lake Constance near the site of today's
airport at Altenrhein. Having no wheels of its own, it was rolled
out of the factory on a huge dolly and then eased down a ramp into
the water. The maiden flight took place on 15 July 1929.
Dornier was not necessarily trying to set a record for size, but
if it was going to be profitable for Deutsche Luft Hansa and other
airlines to operate it, the aircraft needed to be able to carry a large

The flight engineer at his post controlling throttles on the six engines on the
starboard, with his back to similar controls for the six port-side engines.
Photo: Wikimedia Commons.
Jetrader * Spring 2017 41

Jetrader - Spring 2017

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