Propeller Island, by Henri Defrasse – and not Jules Gabriel Verne

The floating island designed by Henri Defrasse. Anon., “Un Nuevo proyecto de isla flotante.” Alas, 1 June 1928, 189.

Welcome and bienvenue, my reading friend. Are you ready to hear about one of the crucial aspects of the history of technology? Yes? Welcome, then, to the world of failure. You seem surprised. Don’t you know that most aircraft designs of the 20th and 21st centuries have been failures? Not every aircraft design was actually put to the test and a great many that were tested were never put in production. Worse still, many operational aircraft did not prove successful, for a variety of reasons. So, we do live in a world chock full of failures. Please keep this thought in mind as you turn your attention to the illustration above, extracted from the pages of the Spanish monthly magazine Alas, one of the many vintage foreign periodicals found in the amazing library of the Canada Aviation and Space Museum in Ottawa, Ontario. Said illustration could well be a black and white version of a drawing / painting made more than 90 years ago by Frenchman Henri Defrasse (1896-?), Arch. D.P.L.G. (Architecte diplômé par le gouvernement).

Our story began in 1923-24 when this son of famous architect Henri Alphonse Alexandre Defrasse completed the plans of a floating seaplane base. By 1928, the detailed study that accompanied these documents had received 2 if not 3 prestigious awards.

Ninety years ago, the giant jet-powered airliners we take for granted were beyond anything the people of the time could imagine. Indeed, airliners capable of carrying passengers across the oceans of the globe simply did not exist. This explains why countries like Germany and the United Kingdom spent a great deal of money building huge rigid airships. Yours truly would like nothing more than spend the next hour pontificating about these giants of the air, and the fascinating visit to Saint-Hubert, Québec, of the British rigid airship R 100, in July and August 1930. I shall resist temptation, however, and stick with the topic at hand. Bribes will not be accepted, for the moment. Come and see me after work, and bring some Romulan ale, but back to our story.

Would you believe that the general consensus in the 1920s was that the transoceanic airliners that would hopefully appear in the following decade would be flying boats rather than landplanes? Flying boats were deemed to be safer given their ability to land in mid ocean in case of emergency. Their use also eliminated the need to build and maintain large and costly runways, but back to our story.

Well aware of the limitations of the airliners of the early to mid 1920s, Defrasse suggested that giant flying boats be used in conjunction with, you guessed it, a network of the aforementioned floating bases. From the looks of it, he proposed that 12 or so of these floating islands be used to facilitate the crossing of the North Atlantic (France – United States), South Atlantic (Afrique occidentale française – Brazil) and Pacific (United States – Japan). Besides their main use as refuelling stops, the floating islands would be very handy if a flying boat suffered mechanical problems or had to seek shelter if bad weather swept in. In either case, passengers and crews would find comfortable accommodations on board. The floating islands could also provide assistance to ships in distress.

And no, Afrique occidentale française was not mentioned in a March 2018 issue of our blog / bulletin / thingee. You are mistaking this federation of French colonies in West Africa with Afrique équatoriale française, a federation of the 4 French colonies in Equatorial Africa. No need to apologise.

You may think that the expression floating island was a mere figure of speech, my reading friend. This, however, would be a mistake. The structure imagined by Defrasse was approximately 220 metres (about 725 feet) wide and 480 metres (1 475 feet) long. Seen from above it looked like a very broad ship with an open stern – or a gigantic horseshoe. The seaplane basin nested within the reinforced concrete structure of the floating island was approximately 335 metres (about 1 100 feet) long and 100 (about 330 feet) metres wide. The depth of the water contained therein was no less than 6 metres (almost 20 feet). Twin mobile barriers and a series of small side openings kept the waves under control. As a result, small flying boats could use this calm water area to take off and land.

The depth of the waters below the floating island was such that any anchoring system would be horrendously complicated, if not impossible, to design. Instead, Defrasse included two powerful sets of Diesel engines in his floating island, which allowed its commander to orient it to facilitate the landing of flying boats even if the ocean was a bit rough. Top speed of the colossal structure was a breathtaking 5 knots (9.25 kilometres per hour / 5.75 miles per hour).

It should be noted that the transoceanic flying boats would not use the seaplane basin to leave a floating island. A flight deck located on the port / left side, near the 5 hangars and the workshop, included an accelerator / catapult powered by electricity that allowed the aforementioned flying boats to fly away even if the ocean was a bit rough. The largest hangar could accommodate a flying boat with a wing span of up to 70 metres (230 feet). Would you believe that the total area of the 5 hangars was almost as large as that of the main building of the Canada Aviation and Space Museum?

Do you have a question, my reading friend? How did each flying boat that landed in the seaplane basin or the open sea get to the flight deck? A fine question, say I. A powered raft would move underneath said aircraft. Its crew would secure the flying boat before moving toward a ramp. The aircraft would then be attached to the chariot of the accelerator / catapult and moved to the flight deck. Do you have any more trick questions, my mischievous reading friend?

How about the passenger accommodations, you ask? Another fine question. An easy one too. If you must know, there would be a terminal and a 165 room hotel on the starboard / right side, not to mention a terrace as well as several staterooms, restaurants, game rooms and covered tennis courts. There would be but one bar. The very size of the floating islands would make these accommodations remarkably stable in bad weather.

The command centre, weather office and radio room would be located at the front of the floating island, near the quarters for its 120 or so crew members, and not far from the stock rooms and workshops. This writer was unable to find the location of the floating island’s sick bay. And yes, the design of this amazing structure island evolved over time, as was to be expected.

As you may well imagine, the floating island designed by Defrasse would have been hugely expensive. No government showed much interest in the project, even though articles about it were published as late as 1928 – if not later. Pity.

The author of these lines wishes to thank all the people who provided information. Any mistake contained in this article is my fault, not theirs.

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Rénald Fortier