Germany's High Seas Fleet in the World War/Chapter 12
Chapter 12 - Airship AttacksEdit
ON the outbreak of war the Navy had at its disposal only three airships, "L 3," "L4" and "L5," of 15,000 cb.m. capacity. The last Zeppelin built during the war bore the number "L 71," and its capacity was 62,000 cb.m. These figures express the gigantic development which the airships underwent. The airships placed at the service of the Fleet were almost all of the Zeppelin type. The firm of Schiitt-Lanz built a few ships as well, which at first were only used experimentally, but subsequently were put to practical use.
Probably no arm of any service has suffered such severe losses as our airships, with the exception of the U-boats. Out of 61 Zeppelins which were assigned to the Fleet in the course of the war, 17, with their whole crews, were destroyed by the enemy, namely "L" 7, 10, 19, 21, 22, 23, 31, 32, 34, 39, 43, 44, 48, 53, 59, 62 and 70.
Twenty-eight airships were lost through stranding and other accidents, such as the burning of sheds in consequence of explosion. The crews of these were all saved, though in six instances they were made prisoner. Six ships had to be placed out of service as being useless; at the end, ten were still left in a condition fit for use.
Owing to the ever-increasing defensive measures of the enemy the airships at the front were built in two sizes, the types being "L50" and "L 70."
The chief distinctive features of the former were five motors, each of 260 h.p., and such as could develop sufficient speed even in the highly rarefied atmosphere of the upper strata of the air; four propellers, all coupled directly to the shafts (the two rear motors are coupled to one propeller); a central gangway, 196.5 m. long; a breadth of 239 m.; a gas capacity of 55,000 cb.m.; a speed of 30 metres per second (about 1 10 km. per hour); a load of 38 tons.
Type "L 70": Seven motors, each of 260 h.p.; six propellers; central gangway, 21 1.5 m.; greatest diameter, 239 m.; volume of gas, 62,000 cb.m.; speed, 35 metres per second (equal to 130 km. per hour); load, 43 tons.
The "L50 " carried a crew of 21, and "L 70" one of 25, among whom were 1 Commander, 1 Officer of the Watch, 1 Quarter-Master, 1 Chief Artificer-Engineer, 2 men for lifting gear (Yeomen of Signals,) 2 men for the balancing gear (Boatswains), 2 Motormen (stoker petty officers) for each motor, 1 Sailmaker, 1 Petty Officer Telegraphist, and 1 Ordinary Telegraphist for the wireless installation.
They carried two machine-guns, and later on a 2-cm. gun as well. The supply of bombs consisted of incendiary bombs of 11.4 kilo weight, and explosive bombs of 50, 100, and 300 kilos.
In order to gain some idea of the difficulties encountered by airships, it may not be out of place to make a few general remarks on the navigation of these ships.
Their main task was scouting. That is why they were retained during the war as a weapon by the Navy; the Army had no use for them. The development of the aeroplane produced a keen competitor and a dangerous opponent. The Flying Service could not, at first, overcome the difficulty of covering the great distances which scouting at sea entailed. It was a question of flying over large sea areas, such as the North Sea, and providing the Fleet with trustworthy information and reports. Flights of twenty-four hours and longer had to be reckoned with, and no flying-man could hold out for so long.
The great load that the airship could carry, combined with its high speed, made it especially suitable for purposes of attack. The dangers to which the airship itself was exposed were best overcome by assigning to the crews some definite task for furthering the war, for which they gladly risked their lives. Any activity which did not bring them into contact with the enemy would not have satisfied them for so long a period as the duration of the war, and this would have hindered the development of this arm of the service.
When navigating on the water you steer for a goal which lies in a horizontal plane, on the surface of the water; the airship has to negotiate a second dimension due to differences in height. And this it is which presents such great difficulties in aerial navigation. In contradistinction to the aeroplane, the load, including its own weight, carried by an airship is not borne by motor power, dynamic lifting power, but by gas-tight cells filled with a gas lighter than air.
Hydrogen of specific gravity 0.07, which was used for filling, gave a ship of 55,000 cub.m. capacity a lifting power of 64,000 kilos. Of these, 26,000 kilos, in round numbers, were taken up by the weight of the unloaded airship itself, so that the load she could carry would be 38,000 kilos, i.e. 38,000 kilos can be packed into the ship before she will float in the air, being neither heavier nor lighter than air. The weight of the crew, stores of benzine and oil, spare parts, supplies of oxygen for the passage through high altitudes, and bombs amounted to about 10,000 kilos; the remainder, about 26,000 kilos, is available for water ballast. This is most essential in order to neutralise such influences as affect unfavourably the carrying power of the ship. At first, when ascending, the upward pressure of the atmosphere ceases; the gas pressure in the cells becomes proportionately greater. In order to equalise the pressure, every gas-cell is provided with a safety-valve through which the superfluous gas escapes; in this event, carrying power is consequently diminished; the ship becomes too heavy. To remedy this, a proportionate weight of water must be thrown out, so that the ship recovers her equilibrium. As a standard of measurement, we may state that for every 100 m. that she rises the ship loses 1 per cent, of her carrying power, that is 640 kilos.
Temperature, both of the air and the gas, also exerts an influence. Cold air is heavier than warm, whereas the lifting power of the gas, on the contrary, is increased by warmth and diminished by cold. In this respect the following law obtains: a change of one degree in the temperature increases or diminishes the carrying power by about 240 kilos. The commander must, therefore, constantly keep an eye on the temperature and judge by the changes what the behaviour of his ship is likely to be.
The weight is also affected by the amount of moisture that collects on the ship's envelope when passing through clouds; ice is also easily formed if the temperature becomes sufficiently low. The additional weight on the ship due to rain may amount to 3,000 kilos, and owing to ice as much as 5 - 6,000 kilos. The heat of the sun's rays and the strong draught caused by rapid progress soon make the deposit due to rain disappear. Ice has the further disadvantage that pieces of it may be hurled through the envelope by the revolving propellers and may possibly pierce the cells so that gas escapes.
Further, since hydrogen is highly explosive, and when mixed in certain proportions with air becomes very dangerous, care must be taken to prevent fire or electric sparks from coming into contact with escaping gas. But the gas escapes of its own accord when the cells are deflated - when in rising the limit of elasticity of the cells is reached, and when the cells are injured, either by pieces of ice or by hostile projectiles. If the hostile missiles generate flames, as incendiary weapons do, then the ship is inevitably destroyed.
Care is needed, too, in thunderstorms. It is best to avoid clouds charged with electricity. If you cannot go round them you should go under or over them. When rising to get over them, in no circumstances must you rise to such a height that the gas completely fills the cells, for owing to the diminished pressure of the air the superfluous gas is bound to escape and a flash of lightning striking this gas mixture will immediately destroy the ship by fire. There is no danger if the ship is struck by lightning if no gas is escaping, so long as the framework is intact. The framework of aluminium is connected throughout the ship, and acts as a conductor for lightning, which passes out by the stern." Instances in which this has happened have been quite frequent; but such experiences, of course, are better avoided if it is possible to do so.
As regards the height at which the gas completely fills the cells, the following should be noted: When a ship has risen above this height and has let off gas and then descended again, the remaining gas is insufficient to fill the cells completely; it only fills the upper part of them, while the lower part remains empty. The ship is then no longer buoyant. The higher the ship has risen, the less gas the cells contain upon descent; it is forced to come down to earth. In this case more water-ballast must be discharged. The water is distributed in ballast-bags along the entire length of the ship. The valves of these bags are connected by wires with the steering car. Every bag holds 1,000 kilos. The commander is in a position to release any quantity of water desired, from whatever part of the ship he thinks proper. Fore and aft of the ship there are another four bags each containing 250 kilos, which can also be opened from the steering car. These differ from the others in that when opened they discharge their contents instantaneously, whereas the others let the water run out slowly. When the ship needs to be lightened suddenly, the containers fore and aft are used, e.g. for a sharp rise when attacked by aeroplanes, or when a cell has been emptied owing to damage by a missile or some other accident, and one end of the ship suddenly becomes heavy; and also when landing with a "heavy" ship.
Below the ship and at the sides the cars are hung. The foremost and largest of these contains the steering-gear in front, next to that the wireless installation, and at the rear a motor. The last car, which hangs on the central line of the ship, carries two motors which both connect with one propeller. The cars at the side each carry one motor.
As soon as there are no guiding objects in sight, such as land, lightships, or one's own warships, by which the ship's position may be ascertained, navigation becomes very difficult, because of the leeway when the wind blows at an angle to the course of the ship. That is where wireless telegraphy comes in; the installation is such that the ships can be called up by directing stations, their whereabouts calculated, and their position reported to them by wireless.
The airship stations were so placed that they lay as near as possible to the coast, and had a sufficient extent of level ground for ascending and landing; but they had to be placed sufficiently inland to obviate the danger of an unexpected attack from the sea. The Navy possessed the following airship stations on the coast of the North Sea: Nordholz near Cuxhaven, Ahlhorn near Oldenburg, Wittmundshaven (East Friesland), Tondern (Schleswig-Holstein). Hage, south of Norderney, was abandoned.
The ideal airship hangar is a revolving shed which can be turned according to the direction of the wind. Unfortunately, we possessed only one such shed, that of Nordholz, as it involves a great deal of time and uncommonly large expense to build them. The problem of building material had also to be faced in the course of the war. Most of the sheds were placed in a position suitable to the prevailing wind in the neighbourhood. It is not possible to take an airship into or out of a shed if the wind blows across its path at a speed of more than 8 metres per second.
This consideration, and the fact that airship attacks had to be made during the time of the new moon, occasioned the long pauses between the raids, pauses which often gave rise to the impression that other influences had led to the abandonment of these activities. This was not so. From the date of the first airship raid on England, on January 15, 1915, no regulations were made limiting the offensive action of the airships. So far as London was concerned, we had orders at first only to attack such establishments as were immediately connected with military work, such as arsenals, docks, batteries and so forth. But this limitation could not be adhered to in the long run, partly because of the difficulty of discovering, these particular places, partly because just round London the defences were especially intense. But it never was the object of an airship raid to attack defenceless dwelling-places. Their aim always was to destroy those establishments which, either directly or indirectly, served some military purpose: munition factories, arsenals, stores, docks, wharves, etc. Airships frequently returned from their expeditions with their full complement of bombs, because they had not been able to make out such targets with sufficient certainty. It would have been easy enough for them before returning to get rid of their bombs and drop them on any place over which they happened to fly, if they had wanted to kill harmless citizens.
Once the airship was in the air there were no further difficulties except such as arose from thunderstorms or very high winds; just as at sea, very bad weather hinders and circumscribes the activities of ships. The revolving shed is a factor of the utmost importance for the future of the airship.
While the U-boats were at full swing at their work of destroying English commerce, the airships with dogged perseverance did their best to contrive their attacks on the island. In March, 1917, a raid was made by five airships. Two of them reached London. In consequence of a considerable freshening of the wind, the return journey became very difficult. "L 2" was forced to descend in Juteborg, "L 35" in Dresden, "L 40" and "L 41" came down to their shed at Ahlhorn. "L 39" (Commander, Lieutenant-Commander Rob. Koch) was driven by the storm to the south-west, passed over the enemy lines in France, and, according to a wireless message from the Eiffel Tower, was shot down at Compiegne. Her crew perished in the flames.
A raid which was started in April had to be abandoned because on the outward journey the weather became unfavourable.
May again presented an opportunity for a successful raid which took place in the night of May 23 - 24. The following took part in it: 'L 40,"L 42," "L 43," "L 44" and "L 45." Captain Strasser, the Head of the Airship Service, was on board the "L 44." The officer commanding the airships made the following report:
- "Towards 1.45 a.m. we crossed the coast near Harwich; cloudy sky with breaks in it. A number of searchlights tried in vain to pick up the ship. Very little gunfire; no aeroplanes. In consequence of three motors missing simultaneously, did not carry out attack on London, as ship lost height rapidly, but dropped bombs to amount of 2,000 kilos on Harwich. Shortly after attack all engines began to miss, ship travelled like a balloon for three-quarters of an hour over enemy country and fell from 5,700 m. to 3,900 m. After this till 10 a.m. travelled with one motor only going, from 10 A.M. with 2-3 motors; landed at Nordholz 7.20 p.m. 'L 43' had to pass through severe thunderstorms with extraordinarily heavy hail-showers on return journey. Lightning struck ship in forepart and ran along the framework without doing any damage."
The next attack was on June 17. "L42," "L43," "L44" and "L45" took part in it. The raid on London was again prevented owing to the shortness of the night, because detours had to be made to avoid several thunderstorms. "L42" could not reach London, and at 3 a.m. expended her entire ammunition on Dover. There was severe gunfire during the attack, but the searchlights could not hold the ship for long owing to heavy mist. The bombs fell on their targets. Violent explosions at intervals of 10 minutes followed one detonation; whole districts of houses seemed to be hurled into the air; fires could be observed for a long time afterwards. Shortly after the raid the ship was pursued and violently bombarded by light craft, apparently torpedo-boats or small cruisers.
From "L 42" it was observed that one of our ships was being attacked by an airman. The airship was at a height of 4,500 - 5,000 metres, with the airman 300 - 500 metres above her. As "L 43" (Lieutenant-Commander Kraushaar) did not return from this journey, we were forced to assume that the airman had destroyed her. Later reports from England confirmed this.
On August 30 the Ordre pour le Merite was conferred on Captain Strasser. I took the opportunity of handing him this distinction personally, and for that purpose went to the airship station at Ahlhorn, 20 km. south of Oldenburg, which had been erected during the war and was now the chief base of the airships.
It is to Captain Strasser's credit that he developed Count Zeppelin's invention to military perfection, and made the airship a weapon of great efficiency, besides rousing the enthusiasm of the crews of the airships by his example. He was the life and soul of the whole and made everyone under his command share his conviction that airships had a great future before them. He was particularly gifted in estimating meteorological conditions. He had an almost prophetic instinct for the weather. How often we have had to apologise mentally to him, when in apparently favourable weather the airships did not go out; for he was always right, and shortly afterwards there was invariably a change in the weather which would have endangered the ships and made their return impossible. But he recognised no such thing as insurmountable difficulties; the stronger the enemy's defence grew, the more energetically did he concentrate on counter-measures. Thus he sent his ships up higher and higher, and ultimately they worked at an altitude of 6,000 metres - a height which was considered impossible at the beginning of the war. For this he needed elbow-room and sympathetic co-operation in his technical suggestions. His organisation of the airship service did not immediately place him in such a position as to get his demands satisfied quickly enough. Moreover, he was hampered by all sorts of difficulties connected with technical administration. Those in command of the Fleet, however, did not rest until the organisation had been changed so that he could have free play in the conduct and development of the airship service.
Captain Strasser took part in most of the airship raids, although permission was often given him very grudgingly. The loss of airships was so considerable that I was always afraid that one of these days he would not come back, and he was too valuable to the airship service for such a risk. But just because the difficulties always grew, I had to admit that he was right in considering it necessary to see for himself what conditions were like on the other side, so as to judge what he could demand of his crews and how he could improve the efficiency of the ships.
An attack in October, 1917, brought about the loss of five airships out of the eleven which set out. This was due to such a strong head wind setting in that four ships were blown far over into France, and one, though it reached Middle Germany, was lost in landing. The six others, thanks to their timely recognition of the change in the weather conditions, came home safely. The individual ships had more than the usual difficulty in determining their positions, because the angles from the directing stations became very steep when the ships were over the South of England, and consequently the calculation of their positions was less accurate.
Another very painful set-back for navigation by airships occurred in January, 1918, when owing to the spontaneous combustion of one of the airships in Ahlhorn, the fire spread by explosion to the remaining sheds, so that four Zeppelins and one Schiitt-Lanz machine were destroyed. All the sheds, too, with one exception, were rendered useless.
After this the Fleet had, for the time being, only 9 airships at its disposal. From the autumn of 1917 onwards, the building of airships had been restricted, because the material necessary for the building of aircraft was needed for aeroplanes for the army. From that date only one ship was placed on order every month. But even this did not prevent us from repeating our attacks on England from time to time, though we had to be careful to incur no further losses, so as not to be without airships for scouting which was so important for the other activities of the Fleet.
On August 5, 1918, the airships of the Navy attacked England for the last time. Captain Strasser was on board the "L70," the latest ship, commanded by Lieutenant-Commander von Lotznitzer. He did not return from this journey; his ship was the only one of those that took part in the raid that was shot down over England. Thus this leader followed his comrades who had preceded him and to whom he had always given a glowing example.
The value of airships as a weapon has been much called into question.
In the beginning of the war, when seaplane-flying was quite undeveloped, they were indispensable to us. Their wide field of vision, their high speed, and their great reliability when compared with the possibilities of scouting by war-ships, enabled the airships to lend us the greatest assistance. But only in fine weather. So the Fleet had to make its activities dependent on those of the airships, or do without them.
A weakish fleet needs scouts to push as far in advance as possible; scouts, too, which can make observations without being driven off. The airships could do this. The danger from aeroplanes only arose later, and was never very serious at sea; but over the land it was extremely unpleasant. Although as a rule an airship can mount more quickly than an aeroplane, yet it has far less chance of hitting its opponent. Ultimately the airships were forced up so high that it was beyond the power of human endurance (altitudes of more than 6,000 m.). That meant the end of their activities as an attacking force. But for far-reaching scouting they retained their importance and their superiority to other aircraft, for they can remain in the air much longer and are independent of assistance from other ships. But the bigger they grew the rarer grew the opportunities for them to go on expeditions, because of the difficulties of getting them out of the sheds, and later on of their landing.
We have no reliable information as to the results of their attacks. They were the first war-engines which scared the English out of their feeling of security on their island, and they forced them to organise a strong defence. To judge by this, their visits must have been regarded as a very considerable menace.
It was our business to make as much use as possible of our superiority in airships, and to increase their efficiency so that fear of them might be a contributory cause in inducing England to make peace possible.
Such an ideal of perfection can only be attained if it is perseveringly sought in spite of the set-backs we endured, and although the opposition we had to overcome was increasingly great.
That is the right warlike spirit - not to give in, but to redouble one's efforts as our airship men did in an exemplary way.
We may probably look upon the military career of the airship as over and done with. But the technical side of airship navigation has been developed in such a high degree by our experience in war, that airship traffic in peace times will derive great advantages from it, and the invention of Count Zeppelin will be preserved as a step in the progress of civilisation.