capacity of about 1,000,000 cubic feet, motors aggregating 1,000
horsepower or over, and a reputed speed of 65 miles per hour. Just what
was the fate of this particular ship did not become known, since
information of a military character has not been permitted to leak out
of Germany from that time on. But capture or destruction has accounted
for many of the intermediate numbers of the series; big German airships
have been brought down in England, in the North Sea, in France, and at
Saloniki, their loss culminating in the disaster to four out of the
fleet of five that attempted a raid over London but were caught by
adverse winds which exhausted their fuel supply so that they were blown
out of control, toward the south of France. French anti-aircraft
batteries or aeroplanes accounted for three of these, while the fourth,
the L-49, was captured intact.
[Illustration: Fig. 23. Nose of Giant L-49 and Group of Sightseers
_Copyright by Underwood and Underwood, New York_]
*L-49.* An essential part of the equipment of every form of German
military apparatus is a means of destroying it in case of capture. In
the case of the big airships, the officers are provided with revolvers
loaded with incendiary bullets, which are fired into the gas bag, so
that until the L-49 was forced to descend in the south of France by the
activities of a battle plane, plus a lack of fuel, no airship of a
recent type had ever been captured intact. In this case, the commander
fired his pistol at the balloon but missed and was prevented from firing
again by a French peasant who "covered" him with a shotgun. The wireless
operator succeeded in using a sledge hammer on some of the apparatus of
the very completely equipped wireless cabin before he was captured but
did not do sufficient damage to prevent reassembly of the parts with
little trouble. With the exception of the earlier type of Zeppelin that
was forced to descend at Luneville prior to the war, the L-49 was the
first that was ever known to have landed undamaged in hostile territory,
as practically all the others were destroyed in the air, most of them
having been wrecked either by aeroplane or anti-aircraft fire. Fig. 22
shows the L-49 as it rested on a hillside at Bourbon-les-Baines, France,
and Fig. 23 shows a close view of the nose of the monster.
_Standardized Parts._ Comparing the L-49 with many of its predecessors
led to the conclusion that it was one of the latest types, but an
inspection of its construction revealed the use of many parts produced
in quantities from standard patterns as well as a lack of the finish
that has always characterized airship construction. Appearance and
comfort had both been sacrificed with a view to saving the last ounce of
superfluous weight in order to carry more fuel and ammunition. Evidently
the production of these large airships has been reduced to a
manufacturing basis and they are constructed in series in much the same
manner as motor cars, though on a reduced scale.
_General Design._ In its general construction the L-49 was along the
same lines that have characterized the Zeppelin since its inception, the
outer envelope being stretched over a rigid frame of aluminum girders,
inclosing a large number of independent balloons inflated with the usual
hydrogen gas, no trace being discovered of the non-inflammable gas, the
discovery of which had been hailed by the German press. The commander’s
cabin was suspended well forward with the wireless room directly behind
it, while a V-shaped gangway, recessed in the envelope proper so as to
present no additional head resistance, ran back from the latter the
whole length of the ship. This and the gun platform on top, mounting two
machine guns and reached by a ladder suspended in a well amidships, have
been familiar features of all the recent Zeppelins. The main envelope
contained nineteen independent gas bags, each of which was made integral
with an air balloonet to take care of the expansion and contraction of
the hydrogen with varying altitudes and temperatures. Distributed along
the lower part of the frame inside the envelope were a series of
50-gallon water-ballast tanks.
_Power Plant._ No less than nine large motors were employed to drive the
huge gas bag, the maximum horsepower probably aggregating 1,600 to
2,000. The motors were distributed in five different locations, the
largest being suspended just abaft the wireless room. The remainder were
placed in self-contained units in the form of gondolas suspended from
the sides of the frame, as shown in Fig. 24, the outline being that of a
blunt-nosed fish. Each of these gondolas carried two motors placed side
by side and coupled up so that either one or both could be employed to
drive the single propeller. For cruising speeds one motor in each
gondola supplied sufficient power or in some gondolas both motors could
remain idle. No accommodation was provided for attendants in the
gondolas, any of which could easily be reached by light ladders from the
inclosed gangway.
To insure greater safety, the fuel supply was divided among sixteen
tanks, all of which were interconnected with each other and the engines
so that gasoline from any tank or tanks could be diverted to any
particular engine. The supply of lubricating oil for each engine was
carried in a tank in the gondola itself.
_Control._ Vertical and horizontal stabilizing surfaces of conventional
form were built on the sharply tapering rear end of the frame, the
elevator and rudder being similar to those used in aeroplane
construction, except that the rudder was in two sections, the larger of
which was placed on top of the envelope. The control of these surfaces,
the operation of all the engines, the control of the water ballast, the
air supply to the balloonets, and the fuel supply to the motors were all
concentrated at a panel board in the commander’s cabin, the forward end
of which bore a close resemblance to the bridge of a man-of-war. By
means of thirty-eight push buttons, half red and half white, air could
be released from or pumped into the balloonets, while in a similar
manner the contents of any one of the water-ballast tanks could be
emptied. Elaborate controls were provided for the power plant, it being
possible to vary the speed or stop any one or more of the motors from
the bridge. The rudder and elevators were operated by means of small
hand wheels, similar to a marine steering wheel. One of the most
prominent features of the operating cabin was a huge chart frame,
capable of carrying a large scale map covering a considerable area, as
well as an ample supply of maps. Few instruments were found in the
captured ship and it is thought highly probable that everything not
fastened in place had been dumped overboard at the last to increase its
lifting power.
[Illustration: Fig. 24. One of Six Gondolas, or Power Units of the
Zeppelin L-49
_Copyright by Underwood and Underwood, New York_]
Apart from the use of standardized fittings and parts and the employment
of a great deal more power in a slightly different manner than had
characterized the earlier types of Zeppelins, the L-49 revealed nothing
of unusual importance in airship design and certainly none of the
world-beating features that German propaganda had been heralding for
some time previous.
*Destruction of Zeppelins.* Mention has already been made of the fact
that practically the only use made by Germany of her huge airships has
been the bombardment of open cities, and that always at night. From the
first of September, 1914, up to the end of 1917, between thirty and
forty had met disaster, but only two were captured intact. The first of
these was discovered by a Russian cavalry patrol while at anchor and its
crew of thirty men were made prisoners. This was at an early period in
the war, while the second one to be captured was the L-49, already
referred to, which formed one of a squadron of five evidently sent out
on a bombing expedition against London. Owing to adverse winds, they
never reached their destination and four of them were known to have been
put out of action, all except the L-49 being destroyed in the air. Not a
few of these big airships have fallen victims to their own weakness and
succumbed to the elements, in one instance a high wind tearing the
airship loose from its moorings while the crew was not aboard. This was
at Kiel, and after traveling a number of miles unguided, the big bag
fell into the North Sea. In quite a number of other cases head winds
have prevented the return of the raiders to their base and they have
either been destroyed by their crews or wrecked at sea in attempting to
return. In still other instances the unwieldy monsters have been wrecked
by high winds when attempting to land, as was so frequently the case
prior to the war.
_Aeroplane and Anti-Aircraft Fire Effective._ Before the war broke out
the ability of either the aeroplane or the anti-aircraft gun to overcome
the Zeppelin was purely theoretical, but actual experience has
demonstrated that much of the theory was well founded. At least three
Zeppelins have been destroyed by British aviators in mid-air, all or
most of the crews being killed, while probably an equal number have been
accounted for by French aviators in open battle. The war had not been
under way a month before French anti-aircraft gunners showed their skill
by bringing down-a "Zep," while only a week later a Russian battery
accomplished the same feat, in this instance killing the entire crew. In
1916, British and French gunners succeeded in either "winging" or
setting on fire three or four, while two dropped into the North Sea and
one was blown up by its crew, having run out of fuel while raiding
Scotch towns.
_Bombing Raids against Zeppelin Sheds._ Not the least of the
disadvantages from which such huge and unwieldy craft suffer is the fact
that the correspondingly large structures required to house them make
exceedingly easy marks for the raiding aviator. Bombing, however, is
such an uncertain art that even such large buildings as these cannot be
struck from any altitude with a fair degree of accuracy. Consequently,
in the number of raids that have been carried out against Zeppelin
sheds, success has been due very largely to the temerity of the
aviators, who have descended within a few hundred feet of their mark
despite the fire directed at them from all quarters. At least three and
probably more of the big airships have been destroyed in this manner by
British aviators, who have made flights of several hundred miles to
reach their destination, while the destruction of as many more has been
ascribed by the Germans to the "accidental" explosion of a bomb in the
shed. In view of the great precautions taken against accident from the
explosion of the bombs carried by the airship itself, it is not
considered at all likely that there was anything accidental about the
wrecking of these craft.
One of the earliest attempts against Zeppelin headquarters at
Friedrichshafen on Lake Constance, which resulted in the destruction of
the L-31, is typical of the plan followed in attacks of this kind. Two
British aviators flew from their base in France, about 250 miles
distant, at a high altitude. They became separated before reaching their
destination owing to a mist. This, however, prevented their discovery
until they had dropped within a few hundred feet of the surface of the
lake, which it was necessary to do to obtain a view of the airship
sheds. The first pilot dropped his cargo of bombs from a height of only
100 feet or so over the shed and was rewarded by seeing it catch fire.
He had hardly straightened out on his return course before he heard the
attack of his companion. The latter was not so fortunate in escaping
unscathed, as a bullet pierced his fuel tank and compelled him to
descend. In the majority of instances, however, the raiders have
succeeded not only in carrying out their task but in escaping undamaged
as well.
CAPTIVE BALLOONS
*Military Value.* As an aid to military operations, the use of the
captive balloon dates back many years. It was extensively employed in
the Civil war and more recently in the Boer war, but with the advent of
both the dirigible and the aeroplane, it was generally considered
outside of Germany that its reason for existence had passed away. The
German military plans included a large number of balloons for artillery
observation purposes and they were used right from the start. It was
only when the fighting settled down to trench warfare, however, that
they came into prominence and the aid that they rendered the German
batteries put their opponents at a serious disadvantage. Like the
bayonet, which was also generally considered to have been relegated to
military operations of the past, the captive balloon is now playing a
very important role, particularly on the western front. In favorable
weather, anywhere from ten to forty of these aerial observation posts
will be visible from a single point on the line.
*Spherical Type Defective.* The captive balloon of the present day,
however, bears no resemblance to its predecessors. From a sphere, it has
been developed into a form that more nearly resembles the dirigible and
at the same time, it embodies some of the features of the aeroplane. The
old spherical balloon was always at the mercy of the wind, which not
only governed the altitude to which the balloon would rise but also made
things extremely uncomfortable as well as dangerous for the observers.
With 1,000 feet of cable out, such a balloon rises to an equivalent
height on a perfectly, calm day. But even a light wind cuts this height
down by 100 or 200 feet, while if a strong wind is blowing, the balloon
is held down to within a few hundred feet of the ground regardless of
the length of cable paid out. Every strong gust beats it over at a
perilous angle and the resulting shocks to the basket are so severe that
its occupants can have little thought for anything but their own safety.
Strong cross gusts set both the bag and basket to spinning and jumping
in a manner that would make the results of the severest storm at sea
seem mild by comparison, since the movements of the basket are executed
with such rapidity that they seem to be in almost every plane
simultaneously. As a result, the old type of captive balloon was
available for service only in the calmest weather.
*Modern Kite Balloon.* It should not be supposed that the improved type
of observation balloon now in use in such large numbers provides any
unusual amount of ease or comfort, since it is also prey to the wind and
does a great deal of swinging about as well as jerking when the wind is
more than 15 or 20 miles an hour. But it has been improved to a point
where the wind not only serves to elevate, instead of depressing it, but
also to steady it. The new type. Fig. 25, is technically known as a kite
balloon, because, in addition to the appendages attached to the bag
itself for steadying purposes, it is equipped with a tail to assist in
keeping it heading into the wind. This consists of a number of
bucket-shaped pieces of heavy canvas attached to the tail cable by
bridles so as to catch the wind and hold it, thus placing a heavy strain
on the cable and preventing the balloon from swinging violently. As is
the case with practically everything used at the front, the technical
name of the new type of balloon is prominent by its absence. It is a
_Drache_ (kite) to the Germans and a "blimp" to Tommy Atkins. Both its
shape and attitude when aloft bear a close resemblance to a huge
sausage, so that the term "sausage" is used by all the belligerents in
common to a large extent. A side view of an American type is shown in
Fig. 26.
[Illustration: Fig. 25. Head-On View of Modern Kite Balloon, Showing
Details of Tail Buckets
_Copyright by Central News Service, New York City_]
It will be noted from Figs. 25 and 26 that the suspension of the basket
and the appendages attached to the balloon at the rear hold it in a
position which is roughly the equivalent on a large scale of the curve
of an aeroplane wing. It has both camber and an angle of incidence, so
that the wind serves to elevate it instead of beating it down. This
lifting effect is further increased by tubes of large diameter, open at
the forward end only and curving around the end of the gas bag at the
rear. (It is also equipped with an air balloonet, the same as a
dirigible.) The wind enters the lower end of this tubular member, which
is in a line with the longitudinal axis of the balloon, but it must pass
around the curve at the end of the gas bag before it can fully inflate
it, so that it performs the double function of increasing the lift and
steadying the balloon, though the latter is its chief purpose. The
basket is suspended quite a distance below the gas bag and has
accommodation for two observers. Like scores of other inventions that
the Germans were the first to utilize on a large scale in the present
war, the kite balloon was not a German creation but was originally
developed in France.
[Illustration: Fig. 26. American Kite Balloon of Latest Type Ascending
_Copyright by Committee on Public Information, Washington, D C._]
*Methods of Inflation.* The average capacity of the kite balloons used
for observation purposes is 28,000 cubic feet. They are inflated with
hydrogen either from a portable generating plant forming part of the
equipment of the balloon company or from a supply carried under high
pressure in heavy steel "bottles" similar to those used for transporting
oxygen or carbonic acid gas intended for industrial use. Since the
balloon companies are stationed about 4 miles back of the firing line,
the use of the portable plant is practical, but it has been found more
economical and more convenient to generate the gas on a large scale at
special establishments in France and England and send it to the front in
containers. With a portable plant, several hours are necessary to
inflate the gas bag, whereas with a large supply of the gas at hand
under high pressure, the operation may be carried out in less than an
hour.
The balloon naturally works under the same difficulties as all
lighter-than-air craft, that is, there is a constant leakage of the
hydrogen through the fabric in addition to that lost by the expansion of
the gas on warm days when the summer sun beats down directly on the gas
bag. Where a field generating plant is employed, quick inflation of a
new balloon or replacement of loss is accomplished by the used of
several "nurses", Fig. 27. These are simply large gas bags which are
kept replenished by the gas plant working constantly, in other words,
they are storage tanks, and when it is necessary to inflate the balloon
quickly, their contents are simply transferred to it.
[Illustration: Fig. 27. Landing Big Kite Balloon at Training Station
"Somewhere in England." "Nurse" in Background
_Copyright by Underwood and Underwood, New York_]
*Balloon Company.* Though aeronautical in character, the kite balloon
service is actually a branch of the artillery, to which it is directly
attached. A balloon company accordingly consists of twelve to twenty
artillery officers of varying ranks and about 120 to 130 men. Of the
officers, six to eight are artillery lieutenants or captains and go
aloft as observers, this number being necessary because the strain of
watching constantly is very great and the observers must be relieved at
frequent intervals, the balloon otherwise being kept up continuously,
both day and night. There are also a number of sergeants, each of whom
is in charge of a different branch of the work, such as the inflation,
transport, telephone service, and winding machine. No less than fifteen
3-ton to 5-ton motor trucks are necessary for each balloon company
besides two or more motorcycle messengers, the care of the machines
usually being entrusted to the corporals of the company. The remainder
of the company are practically laborers, whose chief duties are to
attach the ballast bags to the ropes when it is intended to hold the
balloon on the ground for any length of time and to utilize their own
weight for the same purpose when the balloon is about to go aloft or is
only on the ground temporarily. In addition, every company has its
surgeon and assistants, quartermaster, cooks, company clerk, and other
attaches necessary to complete its organization, since a balloon company
serves as an independent unit.
*Equipment.* The paraphernalia required is quite as elaborate as that
necessary to keep several aeroplanes aloft, though naturally of a
different nature. It must all be readily portable, for a balloon company
has to change camp more or less frequently, or as often as the enemy
artillery happens to discover its range. To secure mobility is the
purpose of the great number of motor trucks employed. One of these is
equipped with a hoisting winch and a large drum capable of holding 3,000
or 4,000 feet of about 3/8-inch steel cable. The winch is driven by the
same engine that propels the truck, and in case of emergency the engine
may be applied to the two purposes alternately within a short space of
time. For instance, in case of attack either by shrapnel from an enemy
battery or by a hostile aviator, it may be used to quickly haul in or
let out cable to change the altitude of the balloon, or it may be
employed to drive the truck to another and more favorable location with
the balloon in tow.
Another truck houses a complete telephone exchange, since the observers
in the balloon may wish to communicate with any one of a number of
batteries which they are serving. Telephone communication is established
by means of an insulated wire which forms the core of the cable, while
the steel cable itself acts as the return wire to complete the circuit.
In some cases, a separate copper cable is employed, using the steel
cable as the return half of the circuit. In addition there is a truck
for transporting the balloons, for the company must always have
duplicate equipment at hand in case of the destruction of the balloon it
is using or, as more frequently happens, damage of a nature that
requires hours or days to repair. In addition to the balloon itself,
there are covers and the ground cloth, as in inflating a balloon no part
of its fabric must be allowed to touch the ground because of the danger
of stones or sticks tearing rents in it. The balloon proper and its
immediate accessories utilize at least one and sometimes two motor
trucks.
To hold the balloon on the ground when out of service, there are eighty
sacks of sand weighing 25 pounds each, or an aggregate of 1 ton of
ballast, in addition to which there are necessary a large number of
steel screw stakes, spare ropes and parts, ladders and the like, besides
the basket and its equipment. The stakes are employed to hold the
balloon down in a heavy wind by "pegging" it in the same manner as a
tent. Three or four trucks are required to carry the large supply of
hydrogen necessary, which entails the transportation of 130 to 150
containers. Each container holds several thousand cubic feet of gas
under high pressure, which is released through a reducing valve. Some of
the other transportation units required are the "cook wagon,"
quartermaster’s stores truck, truck for carrying tents, blankets, and
other impediments for the men, and the "doctor’s wagon" (ambulance).