Page:Popular Science Monthly Volume 90.djvu/534

 Why Zeppelins Are Frightful

��How a Zeppelin is built, how it navigates, and how it drops bombs

By Carl Dienstbach

��THERE are three ways of building a dirigible airship. The first and the oldest consists simply in suspending from a cigar-shaped gas-bag a car in w lich the motor is carried. Such an airship (the non-rigid type), made famous in our time by Santos-Dumont, is apt to "buckle" — in other words, to break or bend in the middle. It can never be made very long for that reason. To prevent buckling the "semi-rigid" type of airship was invented — a type in which a stiff keel is attached to the under side of the long gas-bag, from which keel the car is suspended. The French built many semi-rigid ships of large size and proved conclusively that the idea is fundamentally sound. Then came old Count von Zeppelin, with his rigid type. Zeppelin had been an attache in our Civil War and watched with great interest our attempts of over fifty years ago to use captive balloons for reconnoitering.

An Airship Must Preserve Its Shape at All Altitudes

Von Zeppelin had a good deal more in view than the building of a long airship which would not buckle or break in two. When a balloon or an airship of any kind rises, the gas within the envelope expands. At great heights it becomes necessary to let out some of the gas to prevent the burst- ing of the envelope. When the aeronaut drops later to a lower altitude the gas contracts, with the result that the envelope is only partly filled. That condition is dangerous because the strains are no longer distributed properly. What is more, the shape of the gas-bag is not the best for speedy propulsion. Therefore, all airships, with the exception of those of Count von Zeppelin, use what are known as "ballon- ets" — small air-bags within the big gas-bag. As soon as the airship drops, a blower connected with the air-bag by a pipe is started up in the car, and the air-bag is inflated to such a degree that the gas-bag in turn is distended to the full.

Count von Zeppelin wanted an airship that would preserve its shape at all alti- tudes, something that would not buckle. So he conceived an airship which consists of

��a very light but strong frame several hundred feet long. Within the frame he disposed a dozen and a half separate gas- bags. The outside of the frame was covered with a tightly stretched fabric. From the frame two cars were suspended in the earliest models. The cars were con- nected by a gangway and they contained the motors.

The Art of Building a Zeppelin Is Not Acquired Over Night

Now it is immediately evident that a Zeppelin thus constructed will always have the same shape no matter at what altitude it may be navigated. What is more, only a rigid Zeppelin can be made large enough to travel at very high speed. Everything depends on speed in a Zeppelin. Moreover, several gas-bags can be punc- tured without endangering the lives of the navigators.

It is doubtful if any country could start in at once and build Zeppelins. Indeed, England has tried it and failed. Knowledge of the kind that Count von Zeppelin acquired only after the loss of his entire personal fortune in experimenting and only after much financial assistance from the German people and from the German government is not gained over night. A nation cannot merely copy fallen Zeppelins and hope to succeed. It must do original thinking.

Is the Zeppelin the Surviving Type?

It is still much too early to write the aeronautic history of the present war. This much, however, is certain: With the ex- ception of very small British motor bal- loons, called "convertible aeroplanes," and suitable only for short patroling journeys in fair weather, the Zeppelin is the only dirigible type that has survived the test of warfare. It seems to have totally eclipsed even the German non-rigid and semi-rigid airships. The war has apparently proved that speed is the life and soul of a dirigible, and speed the Zeppelins certainly have when it is considered that they are capable of making as much as sixty miles an hour against a twenty-mile wind and are on the

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