Dornier-X (DO-X) Flying Boat
Completed in June 1929 and first flown on 23 July 1929, the 56-ton Dornier Do-X was then the world’s largest, heaviest, and most powerful flying boat. Powered by 12 engines (six tractor propellers and six pushers), it was designed to carry 66 passengers in luxurious accommodations on long flights (like on an ocean liner) and 100 on short flights. The engines consumed 400 gallons of gas each hour.
The 1930-1931 Promotional Flight
To introduce the airliner to the potential United States market the Do-X took off from Friedrichshafen, Germany, on 3 November 1930, for a transatlantic test flight to New York, just three years after Lindbergh's historic trans-Atlantic flight. The convoluted route (shown in red on the map) first took the Do-X to the Netherlands, England, France, Spain, and Portugal.
Treaty mail from certain European countries was accepted for dispatch via Friedrichshafen with stamps of the country of origin exclusively. The American Air Mail Society (AAMS) catalogue lists these countries as Austria, Danzig, Liechtenstein, Netherlands, Saar and Switzerland, with the possibility of mail “dispatched from Luxembourg (with Luxembourg and Dutch stamps)” (5th ed., vol. 5, p. 2353).
The scarcity of Luxembourg-franked treaty mail is evident from the $1000 value placed on such mail by the AAMS in the 1985 catalog ($1000. in 1985 = $2170. in today’s inflated US dollars).
Luxembourg-Ville, 10 Jan 1931
’sGravenhage, 12 Jan 1931
Transit cancel and DO-X cachet, 15 Jan 1931
At Lisbon, the journey was interrupted on 29 November, when a tarpaulin made contact with a hot exhaust pipe and started a fire that consumed most of the portside wing. The DO-X remained in Lisbon harbor for six weeks, until the end of January, while new parts were fabricated and the damage repaired by Dornier technicians. Additional mail was taken aboard at Lisbon.
Do-X cancel – 30 Jan 1931
Just prior to departing from Lisbon on 31 Jan 1931
The DO-X resumed its demonstration flight on 31 January 1931, and after 7 hours and an average speed of 190 km/h, the flying boat reached its first stop at Las Palmas in the Canary Islands.
But the aircraft was dogged by bad luck. On 3 February shortly before take-off, the Do X collided with a swell that came rolling in. The boat suffered a heavy blow, and the wings were almost torn off. The aircraft was stuck in Las Palmas for the next three months because of the necessary improvements to her structure.
The AAMS catalogue notes that a “few [covers] are known with [the] backstamp of Puerto de la Luz.” citing only Austrian-franked mail as having such a backstamp. (Las Palmas is also known as Puerto de la Luz.) Here the Luxembourg-franked card shown above also bears the backstamp of Puerto de la Luz:
Puerto de la Luz (Canaries) backstamp
26 Mar 1931
The flight continued on from Las Palmas. However, this card was returned from Las Palmas to Rotterdam, where it arrived on 31 March 1931, and from whence it was forwarded to The Hague, the addressee being G.A.G. Thoolen, whose cachet on the back reads “Air Post Specialist ‘s-Gravenhage – Holland.”
Rotterdam Receiving Cancel
31 March 1931
By 5 June 1931, the DO-X had reached the islands of Cape Verde, from which it crossed the ocean to Natal in Brazil, where the crew were greeted as heroes by the local German émigré communities.
The flight continued north to the United States, finally reaching New York on 27 August 1931, almost nine months after departing Friedrichshafen.
Quite a memorable era in aviation and aeropostal history!