Yet with this curious assortment of airships of various sizes, types and ages, the Navy carried on practice patrols covering the areas between Montauk and the Virginia Capes, flying day after day, built an impressive accumulation of flight data, missed very few days on account of weather, made it a point not to miss a rendezvous with the surface fleet. More than any one thing it was this demonstration, over an 18-month period, which led to the revival of an airship program in this country, the ordering of ships and land bases.
Let us see what a blimp patrol is like. The airship can fly up to 65 knots or better, but this is no speed flight. The motors are throttled down to 40 knots, so that the crew may see clearly, take its time, study the moving surface underneath, scrutinize every trace of oil smear on the surface, alert for the tell-tale "feather" of the submarine's wake, air bubbles, a phosphorescent glow at night, for even a bit of debris which might conceal a periscope.
A school of whales, a lone hammerhead shark on the surface or submerged stirs the interest of the patrol, offers a tempting live target for the bombs,--light charges with little more powder than a shot gun shell uses. Now a ship records a direct hit on a shark's back 500 feet below. He shakes his head, dives to escape this unseen enemy aloft. The airship gives chase, follows the moving shadow below, so strikingly resembling a submarine, finds the practice useful.
Of the crew of eight, everyone on the airship is on watch, with an observation tower open on all sides, without interference of wings, as in the airplane. Compared with surface craft, the airship can patrol more area in a dawn to dusk patrol because of its speed and its wide range of unbroken observation.
The submarine is more efficient in relatively shallow depths, but airships have spotted the silhouetted shadow of U-boats in clear water as deep as 70 feet below the surface. The submarine will attempt to maneuver within a mile of its target to launch its torpedoes effectively. But even at a mile away the ten inches of periscope which projects above the surface is difficult for other craft to detect,--either for a cruiser at sea level, or an airplane, flying at relatively high speed, a threat either may miss.
