Can the Germans Bomb New York from the Air?

By Waldemar Kaempffert and Carl Dienstbach

[The American Review of Reviews, May 1918]

[This article is not a romantic essay in pseudo-science, but the solid contribution of two men who have real reputations to sustain among mechanical engineers and scientists. Mr. Kaempffert is editor of Popular Science Monthly, and is widely known as a well-informed and exact writer on scientific subjects. Mr. Dienstbach was one of the first American students of modern aviation, and has made a notably careful study of each advance in the conquest of the air, wherever achieved.—THE EDITOR.]

Picture to yourself an attack from the air on an Atlantic seaport—New York leaps to the mind—and at once you conjure up a fleet of slim, black super-Zeppelins raining death from a height of ten thousand feet. In the next moment you remember the vastness of the Atlantic Ocean, which has not yet been traversed by aircraft. Your momentary fears are dispelled. The foremost aeronautic engineers of Germany reinforce your conclusions. Did they not discuss, last summer, the possibility of a Zeppelin's voyaging across the ocean, after the war, and did they not decide that if all useless cargo were to give place to fuel, New York might be reached, but only if no severe storm were encountered? Evidently the feat is impossible, and that from the German standpoint. Transform the exploit into a daring military adventure involving more than the ordinary aeronautic risks, and the conviction becomes unshakable that New York is safe from Zeppelins. If the Germans themselves conclude that barely enough fuel can be carried for one crossing, how can the vessel ever return? Besides, bombs must be transported. Even for an attack on London, gasoline is sacrificed for high explosives. A bombless Zeppelin setting out from a German base and hovering over New York is a military absurdity.

ESTABLISHING A BASE OF SUPPLIES

But the case of the Zeppelin is not to be so easily dismissed. A secret base of supplies must be established. Where? Clearly, not on the Atlantic seaboard. Perhaps in the ocean itself? Suppose the airship were to set out with a full equipment of bombs, and suppose that it were to meet in mid-ocean a capacious, cargo-carrying "mother" submarine, of the Deutschland species—might it not be possible to refill exhausted reservoirs? New supplies can be easily and quickly shipped. All Zeppelins have electric winches, by means of which tanks can be lowered and raised in less time than a safe is hoisted from the sidewalk to the fifth story of a New York building.

It will not be necessary to provide tanks or steel bottles for replenishing the gas supply of the huge dirigible, for the simple reason that the leakage of gas would not be very great. Zeppelins remain in their sheds for a month and more, and lose so little gas that the pressure within their envelopes is easily brought to standard requirements by an occasional brief connection with the gas tanks. Moreover, it must never be forgotten that a Zeppelin flies like an airplane when it is driven at high speed. In other words, the air pressure beneath its huge bulk has a tremendous lifting effect, so much so that a Zeppelin can rise at a far steeper angle than an ascending airplane can assume. This very aerodynamic lift, to use a technical phrase, enables the navigator to compensate for such slight leakage as may occur at great heights.

But a rendezvous is a necessary prerequisite, and appointments in mid-ocean cannot be kept punctiliously. A delay would involve the risk of being discovered and thwarted in waters almost constantly plowed by merchantmen and convoying warships. A meeting might be effected without much loss of time if a Zeppelin could heave to in a given latitude and longitude as easily as a submarine. Over Europe a Zeppelin's commander always knows exactly where he is, because he is in periodic communication with two widely separated German radio stations. In mid-Atlantic only the signals sent out by Nauen could reach him. If there were at least one German radio station in Southern Europe as powerful as that of Nauen, the task of picking up a submarine in mid-ocean would be simplified; for it would involve merely the application of those principles of radio trigonometry with which every Zeppelin commander is thoroughly familiar. He is thrown back on the traditional navigator's instruments. To be sure, the sextant can be manipulated on a Zeppelin as easily as on a steamer, and more frequently; but before two astronomical observations can be advantageously utilized, the giant bubble of gas may drift so far that the submarine may be missed time and time again. These repeated efforts to effect a meeting must be paid for in fuel.

The conclusion is forced upon us that even the chance of reaching New York in stages is slim. When the difficulties of re-provisioning the airship in mid-ocean are pointed out, it becomes apparent that even with the assistance of a Deutschland a Zeppelin could hardly hope to bomb New York.

THE LESSER ANTILLES A POSSIBLE METHOD OF APPROACH

We have assumed, thus far, that a northerly parallel of latitude would be followed and that for lack of a base on the North American shore, the attempt of a Zeppelin to reach New York with a full load of bombs is not likely to succeed. What if the Atlantic were to be crossed on a southerly course? Are the chances of establishing a refueling station in the South, any better? Assume that the craft starts out from Pola, on the Adriatic. It drops to an isolated spot on the barren coast of Morocco and refills its tanks—a performance quite possible along that sparsely inhabited stretch of land. Rising once more- and speeding toward the Atlantic, which way would the commander lay his course? Straight for the Lesser Antilles, like a buccaneer of the eighteenth century. Among the hundreds of coves that indent the islands and that sheltered the looters of the Spanish Main in their time, a haven could be found where a submarine might lurk with explosives and gasoline. It is even conceivable that a base might be established in Mexico. The coast of that country is not too well patrolled, and among a people not yet brought under complete subjection by the present government, friends enough could be found to further a German enterprise.

A nation which has not hesitated to build and equip a submarine for the purpose of running the British blockade and trading coal-tar products with the United States for nickel and rubber, a nation which has even built a gun with a range of seventy-five miles for the sole purpose of displaying its technical supremacy in the manufacture of military weapons, might deem it worth while to convert this possibility into a sensational reality. By voyaging at a well-chosen level the trade winds could be utilized to reduce the fuel consumption. An attack on the United States by a Zeppelin operated from a West Indian base must of necessity be a desperate maneuver; but futile as it must be from a military standpoint, it is nevertheless feasible.

What then? What would be the range of a craft, freighted to the utmost with those terrible bombs that have been dropped on Antwerp, Bucharest, Paris, and London? Washington, the very brain of the country in this critical time, might sustain some injury. Even New York might learn what it means to have bombs dropped from the sky into its densely packed streets or on its congested wharves, if the Zeppelin's commander were to burn his last drop of fuel and then descend and fire a flaming bullet into the inflammable gas with which his envelope is inflated.

BAD WEATHER THE AIRCRAFT'S FOE

Not more than one attack could be made even on the city most accessible from the Caribbean Sea or the Gulf of Mexico. A super-Zeppelin of the highly developed type that has become familiar to the Allies through the fortunate capture of the L-49 last year, must sooner or later return to its harbor or shed, a huge, especially built structure with a complicated equipment for mooring the great hull on flat cars or boats and guiding it to shelter. A quick return must be made to Europe after a single raid. Now the voyage from Pola, the attack on Washington, the return to the Antilles for fresh fuel, and the home voyage would require at least ten days. The safety and success of the enterprise, therefore, depend entirely on the weather. Zeppelins have been wrecked time and time again by sudden and terrific winds. The guiding minds of so bold and undertaking must therefore calculate the meteorological chances for and against success. Under no circumstances must God fail the Kaiser. Atmospherically considered, the United States from the Gulf of Mexico to Maine is a region of gentle winds in summer—a startling meteorological contrast to the rain and wind that prevail during a German summer. But we, too, have our sudden storms. Is it worth while to run all the meteorological risks for the sake of driving the people of an American city to their cellars? Only the German General Staff can answer. A gambler's chance would have to be taken; but even gamblers occasionally succeed, especially when they are bold.

THE CASE OF THE GIANT SEAPLANE

Less favorable, if anything, than the case of the Zeppelin, is that of the trans-Atlantic seaplane. Although the exploit of a Handley-Page machine in flying from England to Constantinople in order to bomb the Goeben will live as one of the most brilliant exploits of the war, the truth is that a huge flying machine has not the radius of a Zeppelin. The longest flights without stop have thus far been made by lone pilots in rather small machines. The longer radius of large planes is deceptive. It is attained by reducing the number of the crew. Proportionately, the four men who man a German Gotha bombing plane weigh less than the single man who pilots a small long-distance flying machine; but even if these four men were reduced to one, not very much more fuel could be carried, relatively to the fuel required by a mammoth plane. Compared with the giant Zeppelin, the large plane has chiefly speed in its favor—speed which is a kind of insurance that favorable winds will continue as long as the voyage. It was only, after "re-coaling" as it were, only after alighting several times, that the Handley-Page was able to reach Constantinople and to carry a great load of spare parts and tools. The airplane has the limitations of a locomotive; the Zeppelin has some of the advantages of a steamer. A locomotive must be re-fueled more frequently than a ship; so must an airplane.

It must be admitted that the Atlantic could undoubtedly be crossed at the present time by the giant Handley-Page machines of England, the huge Capronis of Italy, and the mammoth Gothas of Germany—but only if bombs are left behind.

If a Zeppelin cannot hope to cross the Atlantic with both an adequate supply of fuel and of bombs, if a Zeppelin cannot be sure of meeting a "mother" submarine in mid-ocean, the possibility of bombing New York with a "Gotha" of the largest size that Germany has thus far built seems positively fantastic.

It is even harder for a seaplane than for a Zeppelin to meet a "mother" submarine in mid-ocean. Unlike the dirigible, the plane would be compelled to descend to the surface in order to re-provision itself. The water must be smooth. In a rough sea the task of taking on fresh fuel becomes difficult, if not impossible; the preliminary run without which an airplane cannot be launched into the atmosphere cannot be made. Even if the weather-be fair but the sea choppy, the plane must stay aloft and perhaps exhaust what little fuel may still remain in the tanks. Contrary winds would hamper the craft as much as they would a Zeppelin, although her greater speed would enable her to stem them more readily. Still, delay would be more fatal because of the seaplane's more limited fuel supply. The giant dirigible can afford to lose time; it actually saves fuel by reducing speed. A seaplane's effective radius depends entirely on speed; it cannot lose a minute on a transatlantic voyage; it can save no fuel by slowing down. The trade winds, comparatively gentle as they are, would add but little to the seaplane's speed, but appreciably to the Zeppelin's radius.

Since the limitations of the giant transatlantic seaplane are more pronounced than those of the Zeppelin, since a base must be found for the seaplane as well as the Zeppelin, the Lesser Antilles again suggest themselves as the site of a secret supply station. From his secret haven he vaults into the air, and heads either for New Orleans, Galveston, Jacksonville, or some other Southern port, or perhaps for the Panama Canal. On the whole, the seaplane is most imperilled while flying over the ocean; the Zeppelin after it has arrived at its Southern base. Both seaplane and Zeppelin must reckon with the weather. There is at least one chance in ten that either type of vessel could operate from the Lesser Antilles, and one chance in fifty that it would be able to return home in safety.

WOULD A SEAPLANE COOPERATING WITH A "MOTHER" SUBMARINE SUCCEED?

A prudent General Staff will decide that the odds are against the use of transatlantic aircraft. What if submarines alone were to be relied upon? What if a Deutschland were to transport a dismounted seaplane in its hold, assemble it on its deck when near these shores and launch it for an attack? The Germans build their huge Friedrichshafen sea planes in sections so that they may be readily transported to the coast of the North Sea. At their destination the planes are assembled and then sent forth to raid English towns. But it takes time to assemble even a Friedrichshafen seaplane—-many hours in fact. It is doubtful, too, if the sections could be fastened together on the low, narrow deck of a submarine over which waves break at frequent intervals. On the other hand it would not be a severe test of ingenuity to design a platform which could be quickly erected on the deck, nor a seaplane which could be assembled more readily than the Friedrichshafen type. Much, again, depends on the weather. But fifty or a hundred miles off the Atlantic coast, one day is often as calm as another. It is conceivable that a single submarine might assemble and launch as many planes as it could carry; the number would depend entirely on the capacity of the vessel. If there is any truth in the report published early in April that the Germans are building submarines of five thousand tons displacement— vessels which can actually engage a small cruiser or destroyer on equal terms—the chief technical difficulty of assembling the craft vanishes. Such a submarine might carry a whole seaplane on its deck and the parts of three more below.

Far more practicable than the dispatching of Zeppelins or seaplanes to a Southern base, is this plan of employing the submarine. When it is considered that the Deutschland on her two voyages to this country was not even sighted, it is not too much to suppose that the tedious process of assembling a plane may be carried out without necessarily involving discovery. The hull of a submarine lies low; it is scarcely visible five miles away.

If Boston, New York, Washington, Baltimore, or Norfolk are bombed by craft thus transported—and the possibility is incontestable—it must be at the sacrifice of the seaplanes employed. If a bombing seaplane were to succeed in picking up its submarine mother, the process of dismembering the craft would be difficult and perilous. Armed patrol boats, destroyers, all the fastest vessels that could be summoned for hundreds of miles by wireless, would scour the coast for the aerial raider. Only by a miracle would he escape. And yet, although his return to the submarine is a possibility too remote for serious consideration, although a bombing pilot's attack would probably end in capture or death, who can deny that New York may be thus bombarded? Lives and machines are not reckoned in waging war. Because an enterprise is suicidal, it is not impossible.

THE "WOLF'S" SEAPLANE MIGHT HAVE BOMBED US

If we can imagine New York bombed by a seaplane transported within striking distance of our Atlantic cities by a submarine, is it asking too much to imagine an ordinary steamer, a sea raider perhaps serving as a thoroughly practical "mother" ship? At once the reply leaps to the tongue: The blockade of the North Sea must be run, and the certainty of capture by swift British or American warships must be faced. To this there is one crushing rejoinder. Only a few weeks ago the last of the German sea raiders, aptly termed the Wolf, returned safely to her home port after wreaking havoc on the high seas. She is one of several German steamers which have successfully eluded the hundreds of vessels that swarm in the waters of Northern Europe and the Northern Atlantic Ocean. But the Wolf, so far as we know, conducted her devastations more efficiently, more methodically than the Moewe and other predecessors of hers.

She actually carried a seaplane, with the aid of which she located her prey. We wonder if any Government official shuddered in alarm at what might well have happened. Who knows but New York may have been in actual danger? There is no technical reason why the commander of the Wolf might not have ordered his plane to fly over Washington or New York and to destroy what it could.

A German raider, to all appearances an ordinary merchantman flying a neutral, even an American flag, can carry more than one seaplane. Awaiting a moment when the water is very smooth, the craft is dropped over-board. How much easier is this than the more difficult feat of erecting an assembling platform on a submarine? To be sure, the risk of being discovered is ever present; but if it is incurred by a Wolf bent on commerce-destroying, it may also be incurred by a Wolf bent on bombing American cities. No technical difficulties need' be overcome; only courage and luck are needed.

THE POSSIBILITIES OF SUBMARINE AND CAPTURED STEAMER

The risk of sending out a raider like the Wolf is always formidable. On the other hand, submarines easily run the British blockade. Suppose we substitute a submarine for a Wolf. What is to prevent a submarine loaded with seaplane sections from capturing an English or American steamer in the Atlantic? From transferring a crew to the prize as well as the seaplane parts? Why should not such a captured ship and its seaplane become a menace to the Atlantic seaboard? To all the objections that may be raised, there is always the sufficient answer: The Germans have captured steamers on the high seas and used them as commerce-destroyers, and the Wolf carried a seaplane. Combine both plans, and the danger that threatens New York and other coast cities becomes very real, very alarming.

New York is not so easily defended as London. A far greater number of batteries and searchlights would be required. Even if the necessary batteries have been mounted—and as yet we have seen no signs of such activity—the defenses could not be moved as far from Manhattan as they have been from the heart of London or Paris. What is more, the guns could be more easily evaded by a daring and skilful man in a fast seaplane-bomber.

NEW YORK—A SHINING MARK

How helpless is New York! Stand on the narrow platform that encircles the top of the Woolworth Building, and you behold the city almost as it appears to an airman flying lower than is his wont. How easily you recognize the clearly defined topographic features of the metropolis! There is the harbor, Governor's Island, and. the Statue of Liberty enlightening the world. Here is Manhattan, a thin tongue protruding into the harbor and washed on either side by the Hudson and East Rivers. Across the Hudson you see Jersey City and Hoboken; across the East River, Brooklyn. A map is not half so easily read. You couldn't lose your way if you were the pilot of an aerial vessel—couldn't even at night.

London, Paris, Berlin, must be scanned for a long time if their principal landmarks are to be identified from on high. New York identifies itself to one who-has but glanced at a map. London has its docks on the Thames; but they are not comparable in extent or importance with those of New York, or in accessibility from the air. Nor is the Thames like the Hudson—a long, lake-like expanse over which a seaplane can glide-faster than any express train. Absolute inky gloom never prevails, even on a moonless night. Water is always distinguishable by its sheen. And New York is a port—a city of great water expanses.

So, the heart of New York, which is the island of Manhattan, is literally cut out for the eye to gaze upon, by the Hudson and East rivers, and the harbor itself. Imagine a seaplane launched fifty miles out at sea and manned by a former officer of a German transatlantic liner, a man who knows the city and its surroundings as well as he does his own pocket. He reaches lower Manhattan.

He flies low to escape the fire of any guns we may have mounted to beat off aircraft. Skimming fifty feet above the docks that line the shores of the Hudson and East rivers, he releases his bombs—incendiary bombs which would set the entire water-side aflame. The projectiles have the motion of the machine and travel at first horizontally. He has only to direct his plane as if it were a gun at the particular wharf which he desires to hit. He cannot miss. Have we not read of the sudden downward swoops made by the airmen of Germany and the Allies on the helpless men in the trenches? The massed fire of rifles is of no avail in stopping such a descent. Have we not read how the flyers as they come spew death from machine-guns fired head-on? These tactics are far safer than those in which a man must indulge in fighting an adversary three miles in the air, or when dodging shrapnel hurled at him by anti-aircraft guns during a reconnaissance trip over the enemy's lines. If a pilot were to fly over New York or its harbor at any ordinary height, he would surely be hit by gunners who would concentrate their fire upon him from widely scattered points. But let him skim over the water at high speed, let him twist and turn as erratically as a swallow, and he is safe. Nothing would oppose him but the futile rifles of the river guards. Surely, enough has here been presented to prove that non-combatants at home may yet experience some of the horrors that have been visited on Paris and London. The attack may never come. But if we cherish the illusion that New York and other coast cities are safe from aerial bombardment, we live in a fool's paradise.

© J. Fred MacDonald, 2013



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