MY 200 PASSENGER ’PLANES AND THEIR CONSTRUCTION.

Star (Christchurch), Issue 19035, 2 April 1930, Page 8

MY 200 PASSENGER ’PLANES AND THEIR CONSTRUCTION.

To-day’s Signed Article

Specially written for the “Star” By Dr Claude Dornier.

(Builder of the largest aeroplane in the world.) On a memorable bright day last autumn the largest aeroplane in the world, the flying boat, DO.X., which I designed and built in my factory on the shores of Bake Constance, was hauled out of the workshops where it had taken shape and launched into the lake ready for its trial Right. There were many anxious spectators along the shore—many of them workmen who had helped in building the giant —but I must confess that I was as anxious as any of them, seated in the control room alongside the pilot, waiting to see if the seaplane which I had dreamed out on paper and watched take shape in wood and aluminium, would actually Ry. importance to form some view of the seaworthiness of each boat. Seaworthiness is not a simple thing to define, and it is not at all clear what qualities are desirable. For the present and, it would seem, for a long time to come, most experts would think it rash to lay down precise requirements. As a personal opinion, the seaplane must be able to fly and to meet prescribed civil or military requirements. It must be able with full equipment, instruments and crew, to carry prescribed loads to a given place in a given time (with reasonable latitude). This implies ability to stait under normal conditions. Next in importance is the ability to make a forced landing, with skilful handling. The materials of construction available at present do not afford the means of building flying boats in a rational way, strong enough to get off in a heavy sea without risk. To meet such requirements the useful load and range would be so heavily reduced that such flying boats would answer no civil or military purp ise and would therefore be practically worthless.

I knew, of course, that it would fly, despite its loaded weight of more than twenty tons, for every detail had been figured out carefully in advance. There was no reason why I should feel at all nervous, sitting there, waiting—but there is always a tenseness at such a moment, and I can only hope I did not look the way I felt. The pilot flashed back his signals to the engine room—the twelve motors roared—the graceful hull cut through ’the water, and in twenty-eight seconds the great wing had borne us up into the sky! The DO.X was a success, and I felt a natural thrill of pride as its designer. Recent Tests. In order to form a complete picture of what the recent ten weeks’ test we have conducted with the 200-passenger DO.X may mean, one must consider that repeatedly, without the slightest difficulty, we have taken off from Lake Constance (1200 feet above sea level) a load of 20,000 kilogrammes, or 44,000 pounds. This is done in less than sixty seconds. We think that we can say with absolute certainty that reliable flight can be made with a load of at least 24,000 kilogrammes or 52,000 pounds. This load is 20,000 pounds more than the weight of 200 passengers, who would weigh 30,000 pounds. That means there is a 20,000 pound margin for fuel. Such a load means that the wings are supporting a total weight of well over 100,000 pounds, or 45,900 kilogrammes. It is a weight equal to the average passenger locomotive! Flying Boats. You may wonder how we knew we could build a 'plane like the DO.X—so huge and so heavy. In order to form a picture of what lies behind this design one must first consider that the importance of the flying boat was first realised in England, and generally developed there. No other country can look back on so long a continuous and systematic development of building flying boats. In Germany we had built many also. So when we came to design a huge flying air liner, we had many good designs to depart from. The construction of the DO.X differs from other seaplanes in having more than two wing spars. The possibility of finer and lighter wing construction are exploited in this type and entirely new lines are followed. One of the most notable new features is that the wing covering is no longer permanently attached to the spars and ribs, but consists of large stiff sell contained plates, which are attached to the wing frames in an easily detachable manner. The engines are installed in pans above the wings. The wings are of sermcantilever construction. Unfortunately the construction of the wings is not the same for the flying boats under comparison m the table, but there is not much difference in weight. Carrying Capacity. Besides the question of carrying capacity, speed and radius of action, it is of special

Seaworthiness. It is difficult to meet the one-sided demands of sea pilots for continuously increasing seaworthiness in v\ew of the tare weight imposed by economic considerations. Yet increase of size opens prospects of removing more or less completely the causes which very often lead to damage in a sea. This refers especially to the frequent damage to running airscrews by waves. It is easy to see the advantage of the DO.X in this respect, with its airscrews 18.9 feet above the waterline. In the DO.X type pilots and mechanics are increasingly safe from seas washing over their positions. At the same time, comfort, endurance and ability to carry out repairs in rough weather are all inc»ea?.ed. The Future. I will have to wait until the DO.X is used in the regular air traffic before I will really be in a position to say that the tonkilometre costs so-and-so much with DO.X. Then I will be able to compare with other aeroplane types and decide whether DO.X comes up to the expectatiuns I have of her from the economic point of view. But one must have time for all this. For the moment we must be satisfied with the great engineering success—and hope for the best. At the moment we are carrying out tests with crude oil engines at the wharf at Friedrichshafen. If the results are good—the fuel consumption of the Diesel crude oil aeroplane engine only amounts to 3.9 pounds per h.p. hour —the DO.X, equipped with engines of this kind, would have a radius of action of about 3600 miles. This is all I have to say about the future! (Anglo-American N.S.—Copyright.)