Galeria

Dornier and His Do-X Flying Boat.

With a wingspan of 157 feet & wing area of nearly 5.000 square feet, Dornier had built the biggest airplane in the world. But, at 72.000 pounds empty, it was also the heaviest. He had hoped to install twelve 640 horsepower Curtis Conquerer liquid-cooled engines, which had become initially unavailable, so Dornier had settle with twelve 525 horsepower Siemens-Halske radial engines, still inadequate for the job.
Richerd Wagner was the pilot for the first flight, leaving Lake Constance on July 12, 1929. The altitude of 13.000 feet of the lake sapped the power of the Do-X's engines of 240hp, and other minor problems. An exhibition flight on September 4, 1929, with 60 passengers, incluiding three U.S. Naval officers, who acclaimed the flight as very impressive.
The engine installation was complex, requiring the engineers to have access to the engines, even in flight. The height of the upper wing surface allowed the men to walk within the wing. Finally, the U.S. policy allowed Dornier to acquire the Curtiss Conqueror engines, which were quickly installed. Tests showed only a marginal improvement in performance. This also was experienced in an October international flight - disappointing the engineers by flying at 105mph, instead of the planned 137mph top speed; and it had a service ceiling of about 1.650 instead of the plannes 5.000 ft ceiling. {Can you imagine flying to Europe on a jet today that would take 5 or 6 hours longer?}
I spite of its short-comings, the Do-X was ready to start its sales trips, which began with a flight to America on November 5, 1930. Multiple mishaps on the American trip didn't completely discourage the Dornier sales force, and they delivered two Do-X planes to Fascist Italy in 1942. They were fitted with Fiat engines, but the Italian found the big plane unsuitable for military usage.
In an attempt to recoup some of Do-X testing money, the German government sent the ship on a 32-city tour through East Prussia, Danzig, northern Germany, and then along the Rhein. The tour ran from June 23 until November 14, 1932 resulting in another propaganda triumph. Another flight was planned for 1933, with the Do-X flying along the Danube to Istanbul, but the plane was in a landing accident, requiring repairs. A few more flights were made before it was taken out of service and put on display at the German Aviation Collection in Berlin, before being destroyed in an RAF raid November 23/824, 1943.

*- In the 1920s the German aircraft designers were in center stage of creating giant planes and lighter-than-air ships that required gigantic hangars. Along with Dornier's Do-X, take a look at Junker's largest, the G-38, a four-engine monster that created a sensation at LUPOSTA in 1929.

Danzig Report Nr. 150 - 2011, page 15.