THE IMPORTANCE OF THE "BLIMP."
Thus, it will be seen that the blimp is an important auxiliary of the flying-machine in the pursuit of the submarines. Both together, in this exciting sport, supplement the swift power-boats called "submarine-chasers."
For some time the Navy Department has trained enlisted men and officers for this work, chiefly at a Gulf port, where a school—it is no war secret—of aviation and ballooning has been maintained. Six officers and 40 men are required for each coast station.
The Navy Department adopted for the blimp a standardized pattern, with definite published specifications, in accordance with which contractors turned them out in numbers. It is a sausage-shaped balloon 160 feet long, with a great diameter of 31-1/2 feet, and containing, when inflated, 77,000 cubic feet of hydrogen gas.
The fabric of the "envelope"—that is to say, of the gas-bag—is coated both outside and inside with rubber. It is required that the balloon shall not lose more than 1 per cent of its gas-content in 24 hours. When inflated it must be able to carry (including its own weight) a total of 5275 pounds.
If the "Zeppelin" be excepted, the blimp is the most highly-developed and scientific heavier-than-air flying machine ever devised. It has a cruising speed of 35 miles an hour, but at a pinch can travel ten miles an hour faster. At the "cruising" rate, it carries enough gasoline to keep going for sixteen hours; at 45 miles, its load of "petrol" will suffice for ten hours.
Even the best war balloons of a few years ago were at the mercy of the winds. It is not so with the blimp. Barring storms, it is able to navigate the air as it wishes. It can rise safely to an altitude of a mile and a half. To furnish fuel for its engine of 100 horsepower it carries, in two tanks, 100 gallons of gasoline.
DESCRIPTION OF THE "BLIMP."
In effect, the blimp is a combination of balloon and aeroplane. Like the latter, it is provided with "skids" (resembling sled runners and made of ash wood), or sometimes with bicycle wheels, for safe landing on terra firma. When designed for sea scouting, floats—cylinders of waterproof fabric stuffed with vegetable fibre—are attached to the skids, or to the wheels, so that the airship, in calm weather, may be able to rest, like a sea bird, on the waves, if desired.
The blimp's balloon envelope must contain two smaller balloons, together holding 19,250 feet of hydrogen gas. The idea, of course, is that if anything happens to the major balloon—puncturing by gunfire or by other mishap—the "balloonets" inside of it will keep the machine afloat.