Why We Chose the Dornier-Wal Type
As the expense of using airships was prohibitive, we could only consider the employment of flying-machines. The choice of type depended upon the idea we could form of the landing conditions among the ice. The highest authority in the “world of polar-exploration,” and many others who had hunted and fished Greenland’s east coast for many years, all contended that there would be many suitable landing places on the numerous big flat ice-floes, and also that we should find water-lanes where the seaplanes could land. Some voices were raised against these contentions but as they were only “voices” we didn’t lay much weight on their opinion, though, as was proved later, these latter were right,—but that is a different matter. We regarded it at that time as certain that we should find plenty of big-enough landing places. Accordingly we based our plans, on making an expedition which could land to carry out observations and which would be of considerably more value than an exploration expedition which would only fly over the ice. An expedition thus equipped would be safer, as a forced landing might have to be made at any time. We decided therefore to use two machines, which would allow the expedition to continue with one plane if the other had to make a forced landing on account of irreparable engine trouble. In a forced landing, too, the machine might be damaged, as there would not be the same opportunity to find a suitable landing-place, as in the case of a voluntary landing. It is also certain that it would double the chances of reaching the goal ahead to set off with two machines rather than with only one,—always, of course, banking on the probability of good opportunities for landing being found.
On the other hand, if such opportunities for landing did not offer, the use of two machines would halve the chances of success, as the risk of engine trouble where two are concerned is naturally double what it would be if only one machine were employed. The arrangements, therefore, were, that both seaplanes’ crews should keep together.
When we made our forced landing on the ice we were convinced that there were no suitable landing places to be found up there, and in consequence we decided that we would only use one seaplane for the homeward flight. We spent some days at first getting both machines ready for a start, because starting conditions were so difficult, that it was an advantage to hold one machine in reserve in case the other should get damaged in attempting to get away; but we discovered that it would take the six of us to tackle the work in each case, so we chose the machine which was in the best condition and therefore safest for the homeward flight.
The reason why I have gone into so many details regarding this side of our plans and our conduct of the expedition, is that we have been publicly criticized “because we flew with two machines over a stretch of territory that offered no landing possibilities, and thus we took a double risk of engine trouble.” This is putting a wrong construction on it. The reason that we continued our northward flight after we had reached 83°, and, being free of the fog, saw that there were only bad chances of landing, was because we naturally had a goal to reach and we thought conditions would improve further north.
Back to the choice of type! In clear weather, especially in sunshine, one can see from overhead unevennesses on a place, even when one cannot be certain that all is clear, as the snow may have “covered-in” some banks of drift-ice. If the weather is hazy, even a voluntary landing is a matter of chance, for it is impossible to see even the biggest undulations in the snow.
There are three kinds of under-carriages to choose from—skis, floats, or flying boats. If one has chosen skis or floats, and should strike against a projection with them, tearing off the under part, the machine will turn over, and a continuation of the flight with the same machine will be impossible.
A flying boat on the contrary has fewer sidewise projections (which means that it would be less exposed to the danger of being damaged by unevennesses) and, furthermore, it will not capsize so quickly. If one has also ordered it of durable aluminium it will afford the uttermost safety. Where a big strain would tear the bottom of a wooden boat (making reparation impossible or at least very difficult in the conditions prevailing up there) under the same strain durable aluminium would only suffer some denting which could be straightened out again if it proved sufficient to hinder progress. Aluminium does not break easily.
There were also other reasons that counted in making the choice of a type of boat. Should one have the intention of rising from deep snow, the burden (of the boat or the machine’s under-carriage) lying on the snow must not be greater than a certain weight on the flat, namely, 600 kilograms per square meter.
As our machine would average a weight of six tons it was a simple matter to calculate that we must lie on an area of at least ten square yards, and even then it would be bearing the maximum weight. Thus, a ski-attachment would be particularly heavy, and the floats would have to be unnecessarily large if the bottom’s lines were to satisfy the seamanlike desire “to rise from the water.”
After making these calculations we were never in doubt, but decided that we should choose a flying boat built of durable aluminium. With regard to ski-machines, we should gain a further advantage in being able to land in, or rise from, possible water-lanes, while in a wooden boat a collision with ice in the water-lanes presented a smaller risk.
The point now was to find the right dur-aluminium boat as Dornier was not the only builder of such boats. If one wishes to rise from loose snow it is not only the flat-weight which counts, but it is distinctly necessary that the bottom lines of the boat must be so designed that no power shall be lost by the unnecessary pushing aside of snow when gliding forward. There was thus only one type of boat which satisfied our demands and that was Dornier-Wal.
Dornier-Wal has furthermore a distinct advantage which we first became aware of up in the ice regions. It has not got wing-floats to afford the necessary stability on the water, but for this purpose—as shown in the illustration—has attached at each side of the propeller a big “flyndre.” During our start from the water-lane the boat sank through the new ice and a part of the weight fell on the “flyndres.” In this way we were able to go to the assistance of N 25 in the capacity of an ice-breaker and help it out of several critical situations. Had there been floats on the wings, too great a weight would naturally have fallen on these, and we should have been unable to avoid damage.
From the above it can be seen that there was nothing else for it but to choose Dornier-Wal for our flight even though it might have been handicapped by certain failings. I cannot at present mention one single failing, but it had numerous advantages. The best of these in my estimation is the fact that it is fitted with Rolls-Royce twin-engines (Eagle IX). I should scarcely have agreed to undertake a flight of this kind without a Rolls-Royce. It is not a matter of “chance” that made Dornier fix Rolls-Royce engines to his Wal type: it would have been bad policy to put anything but the very best engines in a flying-machine of the “Wal’s” high standard.
It will also be noticed from the illustrations that the “Wal” is fitted with two engines and that these are placed immediately behind each other—one pulls and one pushes—thus the aft propeller turns contrariwise to the fore propeller, each rotating in its own way. The wonderfully effective qualities which are thus attained, in conjunction with the suitable lines and ingenious “wing-frontage,” make it possible for a weight equal to that of the machine itself to be lifted. As we started from King’s Bay we had a load of 3,100 kilograms, while the “Wal” itself weighs 3,300 kilograms—yet the machine rose with such ease from the ice that I am sure we could have taken an additional 200 kilograms on board. This very fact seemed most apparent during the hardships we underwent in the ice regions, when we thought longingly of how many boxes of biscuits or how much tobacco we might safely have brought with us. We always closed these ruminations by a unanimous agreement that it was a good thing we had carried no more with us than we actually had brought, for a heavier load might have demanded more revolutions from the engine.
The fact that the “Wal” had twin-engines gave us greater confidence in it. In view of the situation of each engine it is possible with a “Wal” to fly with one engine alone, with a heavy load on board, much more easily than if the engines had been placed by each wing, as they are in many other twin-motor machines. With a light load on board a “Wal” can rise quite easily from the water with one engine alone.
Our machine was built by “S. A. I. di Construzioni Mecchaniche i Marina di Pisa” with only a few unimportant differences from the usual Dornier-Wal. We owe a deep debt of gratitude to the factory’s technical director, Herr Schulte-Frohlinde, for the great interest he showed in our expedition. The director accompanied us to Spitzbergen and superintended the setting up of the machines. In all he spent three months of his valuable time on us. We, who otherwise would have been taken up with this work, could now (while the work of mounting was proceeding) give ourselves up to the completion of other tasks.
We also owe much gratitude to the Rolls-Royce factory. They sent five men to Marina di Pisa to introduce certain new improvements and inventions which they had hardly had time to “try out,” and they also sent Mr. Green with us to Spitzbergen. Mr. Green superintended all the trial flights and cared for the engines as though they were his “darlings.” As he (after his final inspection on the 21st of May) smiled and nodded in answer to my request to be told if all was in order, I set off at full speed feeling just as safe as if I were only going to cross the waters of the fjord.