Aircraft and Submarines

Many other devices to trap, sink or capture submarines have been invented. A large number of these, of course, have been found impracticable. Others, however, have been used with success. Few details of any of these have been allowed to become known.

The most dangerous power of submarines, is their ability to approach very closely to their object of attack without making their presence known to their prey. This naturally suggested that a way be found to detect the presence of submarines early enough to make it possible to stave off an attack or even to assume the offensive against the underwater boat. A recent invention, the perfection of which is due to the work of Mr. William Dubilier, an American electrical engineer, and of Professor Tissot, a member of the French Academy of Science, is the microphone. Few details are known about this instrument except that it records sound waves at as great a distance as fifty-five miles. This would permit in most cases the calling of patrol boats or the use of other defensive means before the submarine would be able to execute an attack.

At the present moment it would appear that the most dangerous enemy of the submarine yet discovered is the airplane or the dirigible. Some figures as to the mortality among submarines due to the efforts of aircraft have been published in an earlier chapter. The chief value of aircraft in this work is due to the fact that objects under the water are readily discernible at a considerable depth when viewed from a point directly over them. An illustration familiar to every boy is to be found in the fact that he can see fish at the bottom of a clear stream from a bridge, while from the shore the refraction of the water is such that he can see nothing. From the air the aviator can readily see a submarine at a depth of fifty feet unless the water is unusually rough or turbid. The higher he rises the wider is his sphere of vision. With the lurking craft thus located the airman can either signal to watching destroyers or may bide his time and follow the submarine until it rises to the surface, when a well placed bomb will destroy it. Both of these methods have been adopted with success. For a time the submarines were immune from this form of attack because of the difficulty of finding a bomb which would not explode on striking the surface of the water, thus allowing its force to be dissipated before it reached the submarine, or else would not have its velocity so greatly checked by the water that on reaching the submarine the shock of its impact would not be great enough to explode it at all. Both of these difficulties have been overcome. The new high explosives have such power, taken in connection with the fact that water transmits the force of an explosion undiminished to a great distance, that many of them exploding at the surface will put out of action a submarine at a considerable depth. Furthermore bombs have been invented, which being fired, not merely dropped from an airplane, will go through the water with almost undiminished momentum and explode on striking the target, or after a period fixed by the assailant. Other bombs known as "depth bombs" are fitted with flanges that revolve as they sink, causing an explosion at any desired depth.

About the actual achievements of the airplane as a foe to submarines there hangs a haze of mystery. It has been the policy of the Allied governments to keep secret the record of submarines destroyed and particularly the methods of destruction. But we know that a few have met their fate from bolts dropped from the blue. In The Outlook Lawrence La Tourette Driggs, himself a flying man of no contemptible record, describes the method and result of such an attack. After recounting the steps by which a brother airman attained a position directly above a submerged submarine preparatory to dropping his bomb, he says:

Down shot his plummet of steel and neatly parted the waters ahead of the labouring submarine. But it did not explode. I could see a whirling metal propeller on the torpedo revolve as it sank. It must have missed the craft by twenty feet.

Suddenly a column of water higher than my position in the air stood straight up over the sea, then slipped noiselessly back. By all that is wonderful how did that happen?

As we covered the spot again and again in our circling machines, we were joined by two more pilots, and finally by a fast clipper steam yacht. The surface of the water was literally covered with oil, breaking up the ripple of the waves, and smoothing a huge area into gleaming bronze. Here and there floated a cork belt, odd bunches of cotton waste, a strip of carpet, and a wooden three-legged stool. These fragments alone remained to testify to the corpus delicti.

"Philip," I said half an hour later, as the hot coffee was thawing out our insides, "what kind of a civilized bomb do you call that?"

"That bears the simple little title of trinitrotoluol; call it T. N. T. for short," replied Sergeant Pieron.

"But what made it hang fire so long?" I demanded.

"It's made to work that way. When the bomb begins sinking the little propeller is turned as it is pulled down through the water. It continues turning until it screws to the end. There it touches the fuse-pin and that sets off the high explosive – at any depth you arrange it for."

I regarded him steadfastly. Then I remarked, "But it did not touch the submarine. I saw it miss."

"Yes, you can miss it fifty yards and still crush the submarine." He took up an empty egg shell. "The submarine is hollow like this. She is held rigidly on all her sides by the water. Water is non-compressible like steel. Now when the T. N. T. explodes, even some distance away, the violent expending concussion is communicated to this hollow shell just as though a battering ram struck it. The submarine can't give any because the surrounding water holds her in place. So she crumples up – like this."

Pieron opened his hand and the flakes of egg shell fluttered down until they struck the floor.

Gunfire undoubtedly is still the most reliable preventive against submarine attacks. Comparatively small calibred guns can cause serious damage to submarines even by one well directed shot. Submarines have been sunk both by warships and merchantmen in this way and many more have been forced to desist from attacks. Not every merchantman, of course, can be equipped with the necessary guns and gunners. Neither equipment nor men can be spared in sufficient quantities. But the efficiency of gun protection has been proved beyond all doubt by many authentic reports of successful encounters between armed merchantmen and submarines in which the latter were defeated.

Ramming, too, has been advocated and tried. It is, however, a procedure involving considerable danger to the attacking boat. For one thing all the submarine has to do is to dive quick and deep enough and it is out of harm's way. Then, too, the chances are that the submarine can launch a torpedo in time to reach the ramming vessel before the latter can do any damage.

There have been reports of submarine duels between Austrian and Italian submarines in the Adriatic in which it was claimed that in each at least one submarine was destroyed, and, at least, in one instance both the duellists were sunk. Generally speaking the fact has been established, however, that submarines cannot fight submarines with any degree of success, except in exceptional cases and under exceptional conditions.

Since the outbreak of the war between the United States and Germany the question of combating the submarine has become more acute than ever. The latest development has been along negative rather than affirmative lines. It has apparently been decided that none of the devices, known at present and capable of destroying submarines, is sufficient either alone or in combinations to defeat the submarines decisively. The best means of balancing as much as possible the losses which German submarines are inflicting on the shipping facilities of the Allies at the present seems to be the unlimited and prompt building of large fleets of comparatively small ships. If this can be accomplished in time, the German submarines undoubtedly will find it impossible to destroy a tonnage sufficient to exert any great influence on the final outcome of the war.

CHAPTER XVII

THE FUTURE OF THE SUBMARINE

The world will not always be at war. Interminable as the conflict by which it is now racked seems, and endless as appear the resources of the nations participating in it, the time must come when victory or sheer exhaustion shall compel peace. People talk of that peace being permanent. That is perhaps too sanguine a dream while human nature remains what it is, and nations can still be as covetous, ambitious, and heedless of others' rights as are individuals. But beyond doubt a prolonged period of peace awaits the world. What then is to be the future of the aircraft and the submarine which had to wait for war to secure any recognition from mankind of their prodigious possibilities?

Of the future of the aircraft there can be no doubt. Its uses in peace will be innumerable. Poor old Count Zeppelin, who thought of his invention only as a weapon of war, nevertheless showed how it might be successfully adapted to the needs of peace merely as a byproduct. As for the airplane both for sport and business its opportunities are endless. Easy and inexpensive to build, simple to operate with but little training on the part of the aviator, it will be made the common carrier of all nations. Already the United States is maintaining an aërial mail service in Alaska. Already too, bi- and triplanes are built capable of carrying twenty-five to thirty men besides guns and ammunition. It is easy to foresee the use that can be made of machines of this character in times of peace. Needing no tracks or right of way, requiring no expensive signalling or operative system, asking only that at each end of the route there shall be a huge level field for rising and for landing, these machines will in time take to themselves the passenger business of the world.

But the future of the submarine is more dubious. Always it will be a potent weapon of war. It may indeed force the relegation of dreadnoughts to the scrap heap. But of its peaceful services there is more doubt. That it can be made a cargo carrier is unquestionably true. But to what good? There is no intelligent reason for carrying cargoes slowly under water which might just as well be carried swiftly on the surface unless war compels concealment. Underwater navigation must always be slower and more expensive than surface navigation, nor does it seem probable that the underwater boats can ever equal in size ordinary ships, though undoubtedly their present proportions are going to be greatly increased.

As a result of the German submarine campaign it is possible that the United States may develop a fleet of underwater merchantmen to circumvent the enemy while this war continues, though there has been but little discussion of it. But even so, commonsense would indicate that such a fleet would be abandoned on the restoration of peace. If anything is to be done toward making the submarine a vessel of ordinary everyday use the present double system of motors – the Diesels for surface navigation and the electric for submerged service – will have to be abandoned. Inventors however are diligently working on this problem to-day. Indeed so well known and successful a builder of submarines as Mr. Simon Lake seemed to have faith in their possibilities as merchant craft. As early as February, 1916, he announced that he had taken out a patent on a new form of cargo-carrying submarine which he described as made up of "nests of light-weight circular tanks of comparatively small diameter surrounded by a ship-shape form of hull." What advantage was to accrue from this type of vessel Mr. Lake has not explained. However the Germans who seemed to originate everything successfully demonstrated that the merchant submarine was a practicable and useful craft with which to beat the blockade.

This was proved by the two successful trips made by the unarmed German merchant submarine Deutschland between Germany and the United States in 1916. Loaded with a cargo of dyestuffs and chemicals she left Bremen on June 14, 1916, and arrived in Baltimore early in July. After a short stay, during which she took on a full return cargo, consisting chiefly of rubber and metal, she started on August 1, 1916, for her return trip to Bremen where she arrived safely soon after August 15, 1916. Once more, in October of the same year she made a successful round trip, docking this time in New London. There was considerable talk about additional trips by other German merchant submarines, but none of them were ever carried out. It has never become known whether this was due to the loss of these merchant submarines or to political relations between Germany and the United States which were then gradually assuming a less friendly form.

Of course, it is true that such boats are blockade runners and in a way, therefore, part and parcel of warfare. But they are unarmed merchantmen just the same and their exclusively mercantile character has been officially acknowledged by the United States Government. Under conditions of peace, however, it is very doubtful whether submarine merchantmen would pay, nor does it seem as if they possessed any advantages at all over surface merchant vessels. Nevertheless they represent an entirely new development of submarine navigation and, therefore, deserve attention.

During her stay in the United States, very few people were permitted to get more than a glance of the Deutschland. As a result, comparatively little became known regarding her mechanical details. The Scientific American, however, in its issue of July 22, 1916, gives a fairly detailed description of this first merchant submarine.

From this account we learn that the Deutschland conforms rather closely to the typical German naval U-boat. The hull proper consists of an internal cigar-shaped, cylindrical structure, which extends from stem to stern, and in its largest diameter measures about twenty feet. Enclosing this hull is a lighter false hull, which is perforated, to permit the entrance and exit of the sea-water, and is so shaped as to give the submarine a fairly good ship model for driving at high speed on the surface and at a much lesser speed submerged. The upper portion of the false hull does not present such a flat deck-like appearance as is noticeable in the naval U-boats. In fact, the whole modelling of the Deutschland, as compared with the naval boats, suggests that she has been fulled out somewhat, with a view to obtaining the necessary displacement for cargo carrying.

The interior cylindrical hull is divided by four transverse bulkheads into five separate water-tight compartments. Compartment No. 1, at the bow, contains the anchor cables and electric winches for handling the anchor; also general ship stores, and a certain amount of cargo. Compartment No. 2 is given up entirely to cargo. Compartment No. 3, which is considerably larger than any of the others, contains the living quarters of the officers and crew. At the after end of this compartment, and communicating with it, is the conning tower. Compartment No. 4 is given up entirely to cargo. Compartment No. 5 contains the propelling machinery, consisting of two heavy oil engines and two electric motors. The storage batteries are carried in the bottom of the boat, below the living compartment. For purposes of communication, a gangway, 2 feet 6 inches wide by 6 feet high, is built through each cargo compartment, thus rendering it possible for the crew to pass entirely from one end of the boat to the other.

The length of the Deutschland is about 315 feet; beam 30 feet, and draught 17 feet. For surface propulsion and for charging the batteries, the boat carries two 4-cylinder, Diesel, heavy-oil motors of about 600 H. P. each. The speed at the surface is from 12 to 13 knots; and submerged it is 7 knots. At the surface the displacement of the boat is about 2000 tons, and she has a cargo capacity of about 700 tons.

The freeboard to the main deck, which runs the full length of the boat, but is only about 5-½ feet wide, is about 6 feet, and the cockpit at the top of the conning tower is about 15 feet above the water. This cockpit, by the way, is suggestive of the protection afforded a chauffeur in an automobile, there being a shield in front of the quartermaster, so shaped as to throw the wind and spray upwards and clear of his face.

Two periscopes are provided; one at the forward end of the conning tower, and the other, of larger diameter, being forward and on the starboard of the conning tower. An interesting feature is the two folding, steel, wireless masts, about 50 feet in height, both of which fold aft into pockets built in the deck of the ship. The forward one of these masts carries a crow's nest for the lookout.

The commander of the Deutschland, Captain Paul König, was before the war a popular captain of North German Lloyd liners. He has published a very vivid and interesting account of the Deutschland's trip, the Voyage of the Deutschland. In this book, he tells us how he was offered this novel command while the plans were still being drawn and that he immediately accepted, making, however, the proviso "if the thing really comes off."

The men, backing the venture, lost no time and, so Captain König tells us, in less than two months a telegram called me to Berlin to an important conference. Here I looked at sketches, plans, and working drawings until my eyes swam. Four more months passed which I utilized to the full. I then went to Kiel and saw a remarkable framework of steel slowly take shape upon the stocks across the way at Gaarden. Rotund, snug, and harmless the thing lay there. Inside it were hidden all the countless, complicated, and powerful features of those sketches and working drawings. I cannot boast that the reality as executed in steel and brass was any easier to grasp than the endless network of lines and circles which had bewildered me when inspecting the blueprints.

Those of you who have seen illustrations and photographs of the interior of the "central station" or the "turret" of a submarine, will understand what I mean. And should you have entered a submarine itself and felt yourself hopelessly confused by the bewildering chaos of wheels, vents, screws, cocks, pipes, conduits – above, below, and all about – not to speak of the mysterious levers and weird mechanisms, each of which has some important function to fulfill, you may find some consolation in the thought that my own brains performed a devils' dance at the sight.

But after this monster, with its tangle of tubes and pipes, had been duly christened, and its huge grey-green body had slid majestically into the water, it suddenly became a ship. It swam in its element as though born to it – as though it had never known another.

For the first time I trod the tiny deck and mounted the turret to the navigation platform. From here I glanced down and was surprised to see beneath me a long, slender craft – with gracious lines and dainty contours. Only the sides, where the green body vaulted massively above the water, gave an indication of the huge size of the hull. I felt pride and rapture as my eye took in this picture. The fabric swayed slightly beneath my feet – an impressive combination of power and delicacy.

And now I know that what had at first seemed to me nothing more than the product of some mad phantasy on the part of the technicians was in reality a ship. It was a ship in which oceans might be crossed, a real ship, to which the heart of an old sailor like myself might safely attach itself.

Then came a short period of trial trips and diving tests, all of which were carried off successfully, and at last the day of departure arrived. As soon as the last escort had turned around a final diving test was ordered.

Instantly the response came back from the turret and the central station, and the men hurried to their posts. The oil engines were still hammering away at a mad rate. I left the manhole of the turret. The cover was battened down, the engines stopped at the same moment.

We felt a slight pressure in our ears for a moment. We were cut off from outside and silence reigned. But this silence was merely an illusion – and was due to the change.

"Open the diving-valves! Submerge!"

The valves were flung open and the compressed air escaped hissing from the tanks. At the same time a gigantic, intermittent snorting ensued, like the blowing and belching of some prehistoric monster. There was an uncomfortable pressure in our ears, then the noise became more regular, followed by a buzzing and a shrill hum. All the high notes of the engines in the central station intermingled and made a bewildering noise. It was like a mad diabolical singsong. And yet it was almost like silence after the dull, heavy pounding of the oil-motors – only more insistent and irritating. The penetrating hum in the various vents announced the fact that the diving mechanism was in operation. It moaned and sang lower and lower in the scale of tones. These slowly diminishing and steadily deepening tones give one the physical feeling of mighty volumes of water pouring in and flooding full.

You have the sensation of growing heavier and sinking as the boat grows heavier and sinks, even though you may not be able to see through the turret window, or the periscope, how the bows are gradually submerged and the water climbs higher and higher up the turret until all things without are wrapped in the eerie twilight of the depths.

The faithful lamps burned, however, and then a real silence suddenly ensued. There was no sound but the gentle trembling rhythm of the electric engines.

I then gave the order:

"Submerge to twenty meters!"

"Both engines half steam ahead!"

I was able to follow our submersion by means of the manometer. Through flooding the tanks, the boat is given several tons over-weight and the enclosed ship's space is made heavier than the displaced quantity of water. The titanic fish, therefore, began to sink downward in its element, that is to say, it began, in a certain sense, to fall. At the same time the electric engines are put into motion and the propulsive force of the propellers acts upon the diving rudders and causes the sinking to become a gliding. After the required depth has been reached – something which may easily be read from the manometer that records the depth – all further sinking may be stopped by simply lightening the hull, which is done by forcing out some of the water in the submarine's tanks. The furious growling of the pump is always a sure sign that the required depth is being approached. The noise ceased, only the electric motors continued to purr, and the word came from the central station:

"Twenty meters – even keel!"

"Rudder set!"

So we forged ahead at a depth of twenty meters. Of course we are "blind" under such conditions and can regulate our movements only by means of the depth recorder and that precious little jewel of the boat, our compass. No ray of light reached us any longer from without, the periscope was submerged long ago and the steel safety covers over the windows were closed. We had been metamorphosed completely into a fish.

Orders were then given to rise again. The Deutschland carried out this manœuvre with the same facility with which she had taken the initial dive of her long voyage. In record time the ballast tanks were emptied and the change from electric motors to oil engines was completed without further loss of time. The boat was started at top surface speed towards her ultimate goal, the United States.

On the following day the Deutschland barely escaped running foul of a British submarine chaser, disguised as a neutral merchantman. A quick dive alone saved her. When she came up again a wild storm and a heavy sea were raging. Even before the change from the electric motors to the oil engines had been completed, another dangerous looking vessel appeared and before long was recognized as a hostile destroyer by Captain König. He tells us that he "Made one jump into the turret and slammed the cover fast."

"Alarm! Dive quickly! Flood!"

"Set diving rudder!"

"Twenty meters' depth!"

The commands were uttered in almost one breath. But the execution of them!