My Airships/Chapter 6

by Alberto Santos-Dumont

I YIELD TO THE STEERABLE BALLOON IDEA

DURING my ascent with M. Machuron, while our guide rope was wrapped around the tree and the wind was shaking us so outrageously, he improved the occasion to discourage me against all steerable ballooning.

"Observe the treachery and vindictiveness of the wind," he cried between shocks. "We are tied to the tree, yet see with what force it tries to jerk us loose." (Here I was thrown again to the bottom of the basket.) "What screw propeller could hold a course against it? What elongated balloon would not double up and take you flying to destruction?"

It was discouraging. Returning to Paris by rail I gave up the ambition to continue Giffard's trials, and this state of mind lasted with me for weeks. I would have argued fluently against the dirigibility of balloons. Then came a new period of temptation, for a long-cherished idea dies hard. When I took account of its practical difficulties I found my mind working automatically to convince itself that they were not. I caught myself saying: "If I make a cylindrical balloon long enough and thin enough it will cut the air . . . " and, with respect to the wind, "shall I not be as a sailing yachtsman who is not criticised for refusing to go out in a squall?"

At last an accident decided me. I have always been charmed by simplicity, while complications, be they never so ingenious, repel me. Automobile tricycle motors happened to be very much perfected at the moment. I delighted in their simplicity, and, illogically enough, their merits had the effect of deciding my mind against all other objections to steerable ballooning.

"I will use this light and powerful motor," I said. "Giffard had no such opportunity."

Giffard's primitive steam-engine, weak in proportion to its weight, spitting red-hot sparks from its coal fuel, had afforded that courageous innovator no fair chance, I argued. I did not dally a single moment with the idea of an electric motor, which promises little danger, it is true, but which has the capital ballooning defect of being the heaviest known engine, counting the weight of its battery. Indeed, I have so little patience with the idea that I shall say no more about it except to repeat what Mr Edison said to me on this head in April 1902: "You have done well," he said, "to choose the petroleum motor. It is the only one of which an aeronaut can dream in the present state of the industry; and steerable balloons with electric motors, especially as they were fifteen or twenty years ago, could have led to no result. That is why the Tissandier brothers gave them up."

In spite of the recent immense improvements made in the steam-engine it would not have been able to decide me in favour of steerable ballooning. Motor for motor it is, perhaps, better than the petroleum motor, but when you compare the boiler with the carburator the latter weighs grammes per horse-power while the boiler weighs kilogrammes. In certain light steam-motors, that are lighter even than petroleum motors, the boiler always ruins the proportion. With one pound of petroleum you can exert one horse-power during one hour. To get this same energy from the most improved steam-engine you will want many kilogrammes of water and of fuel, be it petroleum or other. Even condensing the water, you cannot have less than several kilogrammes per horse-power.

Then if one uses coal fuel with the steam-motor there are the burning sparks; while if one uses petroleum with burners you have a great amount of fire. We must do the petroleum motor the justice to admit that it makes neither flame nor burning sparks.

At the present moment I have a Clement petroleum motor that weighs but 2 kilogrammes (4${\tfrac {1}{2}}$ lbs.) per horse-power. This is my 60 horse-power "No. 7," whose total weight is but 120 kilogrammes (264 lbs.). Compare this with the new steel-and-nickel battery of Mr Edison, which promises to weigh 18 kilogrammes (40 lbs.) per horse-power.

The light weight and the simplicity of the little tricycle motor of 1897 are, therefore, responsible for all my trials. I started from this principle: To make any kind of success it would be necessary to economise weight, and so comply with the pecuniary, as well as the mechanical, conditions of the problem.

Nowadays I build air-ships in a large way. I am in it as a kind of lifework. Then I was but a half-decided beginner, unwilling to spend large sums of money in a doubtful project.

Therefore I resolved to build an elongated balloon just large enough to raise, along with my own 50 kilogrammes (110 lbs.) of weight, as much more as might be necessary for the basket and rigging, motor, fuel, and absolutely indispensable ballast. In reality I was building an air-ship to fit my little tricycle motor.

I looked for the workshop of some small mechanic near my residence in the centre of residential Paris where I could have my plans executed under my own eyes and could apply my own hands to the task. I found such an one in the Rue du Colisée. There I first worked out a tandem of two cylinders of a tricycle motor—that is, their prolongation, one after the other, to work the same connecting-rod while fed by a single carburator.

To bring everything down to a minimum weight, I cut out from every part of the motor whatever was not strictly necessary to solidity. In this way I realised something that was interesting in those days—a 3${\tfrac {1}{2}}$ horse-power motor that weighed 30 kilogrammes (66 lbs.).

I soon had an opportunity to test my tandem motor. The great series of automobile road-races, which seems to have had its climax in Paris-Madrid in 1903, was raising the power of these wonderful engines by leaps and bounds year after year. Paris-Bordeaux in 1895 was won with a 4 horse-power machine at an average speed of 25 kilometres (15${\tfrac {1}{2}}$ miles) per hour. In 1896 Paris-Marseilles-and-return was accomplished at the rate of 30 kilometres (18${\tfrac {1}{2}}$ miles) per hour. Now, in 1897, it was Paris-Amsterdam. Although not entered for the race it occurred to me to try my tandem motor attached to its original tricycle. I started, and to my contentment found that I could keep well up with the pace. Indeed, I might have won a good place in the finish—my vehicle was the most powerful of the lot in proportion to its weight, and the average speed of the winner was only 40 kilometres (25 miles) per hour—had I not begun to fear that the jarring of my motor in so strenuous an effort might in the long run derange it, and I imagined I had more important work for it to do.

For that matter, my automobiling experience has stood me in good stead with my air-ships. The petroleum motor is still a delicate and capricious thing, and there are sounds in its spitting rumble that are intelligible only to the long-experienced ear. Should the time come in some future flight of mine when the motor of my air-ship threatens danger I am convinced that my ear will hear, and I shall heed, the warning. This almost instinctive faculty I owe only to experience. Having broken up the tricycle for the sake of its motor I purchased at about this time an up-to-date 6 horse-power Panhard, with which I went from Paris to Nice in 54 hours—night and day, without stop—and had I not taken up dirigible ballooning I must have become a road-racing automobile enthusiast, continually exchanging one type for another, continually in search of greater speed, keeping pace with the progress of the industry, as so many others do, to the glory of French mechanics and the new Parisian sporting spirit.

But my air-ships stopped me. While experimenting I was tied down to Paris. I could take no long trips, and the petroleum automobile, with its wonderful facility for finding fuel in every hamlet, lost its greatest use in my eyes. In 1898 I happened to see what was to me an unknown make of light American electric buggy. It appealed alike to my eye, my needs, and my reason, and I bought it. I have never had cause to regret the purchase. It serves me for running about Paris, and it goes lightly, noiselessly, and without odour.

I had already handed the plan of my balloon envelope to the constructors. It was that of a cylindrical balloon terminating fore and aft in cones, 25 metres (82${\tfrac {1}{2}}$ feet) long, with a diameter of 3*5 metres (11${\tfrac {1}{2}}$ feet) and a gas capacity of 180 cubic metres (6354 cubic feet). My calculations had left me only 30 kilogrammes (66 lbs.) for both the balloon material and its varnish. Therefore I gave up the usual network and chemise, or outer cover; indeed, I considered this second envelope, holding the balloon proper within it, to be not only superfluous but harmful, if not dangerous. Instead I attached the suspension cords of my basket directly to the balloon envelope by means of small wooden rods introduced into long horizontal hems sewed on both sides to its stuff for a great part of the balloon's length. Again, in order not to pass my 30 kilogrammes (66 lbs.), including varnish, I was obliged to have recourse to my Japanese silk, which had proved so staunch in the "Brazil."

After glancing at this order for the balloon envelope M. Lachambre at first refused it plumply. He would not make himself a party to such rashness. But when I recalled to his memory how he had said the same thing with respect to the "Brazil," and went on to assure him that, if necessary, I would cut and sew the balloon with my own hands, he gave way to me and undertook the job. He would cut and sew and varnish the balloon according to my plans.

The balloon envelope being thus put under way I prepared my basket, motor, propeller, rudder, and machinery. When they were completed I made many trials with them, suspending the whole system by a cord from the rafters of the workshop, starting the motor, and measuring the force of the forward swing caused by the propeller working on the atmosphere behind it. Holding back this forward movement by means of a horizontal rope attached to a dynamometer, I found that the traction power developed by the motor in my propeller with two arms, each measuring one metre across, was as high as 11*4 kilogrammes (25 lbs.). This was a figure that promised good speed to a cylindrical balloon of my dimensions, whose length was equal to nearly seven times its diameter. With 1200 turns to the minute the propeller, which was attached directly to the motor shaft, might easily, if all went well, give the air-ship a speed of not less than 8 metres (26${\tfrac {1}{2}}$ feet) per second.

The rudder I made of silk, stretched over a triangular steel frame. There now remained nothing to devise but a system of shifting weights, which from the very first I saw would be indispensable. For this purpose I placed two bags

of ballast, one fore and one aft, suspended from the balloon envelope by cords. By means of lighter cords each of these two weights could be drawn into the basket (see Fig. 3), thus shifting the centre of gravity of the whole system. Pulling in the fore weight would cause the stem of the balloon to point diagonally upward; pulling in the aft weight would have just the opposite effect. Besides these I had a guide rope some 60 metres (200 feet) long, which could also be used, at need, as shifting ballast.

All this occupied several months, and the work was all carried on in the little machine-shop of the Rue du Colisée, only a few steps from the place where later the Paris Aéro Club was to have its first offices.