Page:Popular Science Monthly Volume 90.djvu/538

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��Popular Science Monthly

���The early car of the Zeppelin and the new car are here contrasted. The new car is far more comfortable. It is roofed over probably to prevent the possibility of a chance spark reaching the gas envelope above rather than for any protection required by the navigators. Note the positions of the machine guns near the motor, which is unfortunate because of the motor vibration

��craft aloft. The gas in a Zeppelin (but not in other types because they are too slow) is required for buoyancy only when the ship is standing still or merely drifting. Down on the ground, in starting and land- ing, the gas is a blessing.

By giving his titanic structures a speed greater than that of most railway trains, Count von Zeppelin has at one stroke removed all the fatal imperfections of bal- loon support — the fluctuations in displace- ment resulting from the chilling effect of high altitudes on confined gas as well as the changes in volume that take place in rising and falling.

I have spoken at some length about speed and the aeroplane lifting effect of a Zeppe- lin because the entire future of the dirigible depends on its transformation when in motion into an efficient aeroplane. More- over, the Zeppelin is regarded both in Great Britain and in the United States as an out-and-out dirigible. Only recently an illustrated London weekly attempted to demonstrate the harmlessness of a Zeppelin by graphically depicting its diminishing gas lift at increasing altitudes. The power- ful aeroplane lift was not considered at all! Similarly, in a presumably authoritative

��American review of European dirigibles, published just before the war, the aeroplane lift of a Zeppelin was considered negligible. And yet the Germans themselves con- stantly harped upon it! In one German official publication, for example, it was plainly enough stated that without aero- plane lift, a Zeppelin would be an impos- sibility.

Advantages of Speed and Carrying Capacity

Next to speed, the most astonishing feature of a Zeppelin is its carrying capa- city. That has its merits, especially in a fighting craft. It means that much cargo can be supported at high altitudes and that the favorable swift upper currents, prevail- ing chiefly at high altitudes, can be utilized for speedy journeys. It costs thousands of. dollars to inflate a Zeppelin with hydrogen j gas. Unlike other airships a Zeppelin need" not be inflated to the full at low altitudes,; but with just enough to allow for complete] expansion at high altitudes. No loss isj incurred to relieve pressure.

The third advantage which accrues to Zeppelin because of its great size, the ac vantage of enormous radius of action, is

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