Transcriber’s Note: Italic text is enclosed in _underscores_.
Additional notes will be found near the end of this ebook.




The Daily Telegraph

WAR BOOKS


AIRCRAFT IN WAR


[Illustration:

                                                     [_Topical Press._
  A FARMAN ARMED SCOUTING BIPLANE,

showing gun mounted in position, Gnome motor, ailerons on upper plane,
rudders at rear (see Chapter VII.).]




                           AIRCRAFT _in_ WAR


                                  _By_

                     ERIC STUART BRUCE, M.A. Oxon.

  _Fellow of the Royal Meteorological Society; late Honorary Secretary
      and Member of Council Aëronautical Society of Great Britain;
       Vice-President of the Aërial League of the British Empire;
              Membre d’Honneur of the Aëro Club of France_


                              ILLUSTRATED


                          HODDER AND STOUGHTON
                   LONDON      NEW YORK      TORONTO
                                 MCMXIV




TO MY WIFE,

_who during the eight years of my Honorary Secretaryship of the
Aëronautical Society of Great Britain incessantly and most materially
aided me in my efforts to secure the united interest of the British
nation in the mastery of the air, I dedicate this little volume_.




CONTENTS


  CHAPTER                                                           PAGE

        INTRODUCTION                                                  ix

     I. THE EARLIER AËRIAL SCOUTS                                      1

    II. THE DEVELOPMENT OF THE AIRSHIP                                11

   III. TYPES OF MODERN AIRSHIPS: BRITISH, FRENCH, GERMAN, ITALIAN,
            RUSSIAN, AUSTRIAN, AND BELGIAN                            18

    IV. THE GERMAN AIRSHIP FLEET                                      37

     V. ADVANTAGES AND DISADVANTAGES OF AIRSHIPS                      50

    VI. THE ADVENT OF THE AËROPLANE                                   78

   VII. TYPES OF AËROPLANES: BRITISH, FRENCH, ITALIAN, RUSSIAN,
            AUSTRIAN, BELGIAN, AND BULGARIAN                          91

  VIII. GERMANY’S AËROPLANE EQUIPMENT                                123

    IX. THE FIRST USE OF THE AËROPLANE IN WAR--TRIPOLI--THE
            BALKANS                                                  137

     X. THE NEW ARM IN ARMAGEDDON                                    144

    XI. PRESENT DEFICIENCIES AND FUTURE POSSIBILITIES OF THE
            MILITARY AËROPLANE                                       166




INTRODUCTION


When years ago we read in Tennyson’s “Locksley Hall” the following
lines:--

    Heard the heavens fill with shouting, and there rained a ghastly dew
    From the nations’ airy navies grappling in the central blue--

we little dreamt that not very far from the beginning of the twentieth
century the fancy of the poet would become the fact of reality; that in
the great European war in which the nation is so strenuously engaged,
“the wonder that would be” would come to pass.

Though happily, at present, in these isles the din of war is unheard,
yet a semi-darkened London and bright searchlights playing on the
skies tell the tale of prudent foresight against the advent of the
enemy’s airfleet. From the battlefields there daily come the reports of
actual battles in the air, sometimes betwixt aëroplane and aëroplane,
sometimes between the lighter and heavier than air craft. Often such
encounters are death-grip duels. Such conflicts of the air are the
direct consequence of the great and important use of both airship and
aëroplane as aërial scouts. These are the eyes of encountering armies.
To destroy as far as possible this penetrating vision of the enemy and
restore to him the fog of war is the untiring aim of either side.

During those first anxious days of the present war the public anxiously
awaited news of the doings of the Royal Flying Corps, as well as those
of the aviators of our Allies. Expectation was satisfied in the reading
of Sir John French’s report to Lord Kitchener, dated September 7th,
1914. Speaking of the use of the aëroplane in the war he says:--

    I wish particularly to bring to your Lordship’s notice the
    admirable work done by the Royal Flying Corps under Sir David
    Henderson. Their skill, energy, and perseverance have been beyond
    all praise. They have furnished me with the most complete and
    accurate information, which has been of inestimable value in the
    conduct of the operations. Fired at constantly both by friend and
    foe, and not hesitating to fly in every kind of weather, they have
    remained undaunted throughout.

    Further, by actually fighting in the air, they have succeeded in
    destroying five of the enemy’s machines.

For those brave heroes of the air our hearts beat with fervid
admiration. In accomplishing their all-important tasks they have not
only to fear disaster from shot and shell of the enemy, but from
the mistaken fire of their comrades and the very forces of nature.
These latter, owing to the imperfections of the flying machines, do
not entirely spare them; the Royal Flying Corps, in order to become
competent to perform the work it is now doing for King and country,
has had in manœuvres at home to pay a high price in the sacrifice of
human life.

It may, indeed, be reasonably thought that the knowledge of the vast
utility of aircraft in the present conflict will dispel the last
remnant of prejudice in this country against the development of aërial
navigation, and the grudging of a liberal national expenditure on
the service of the air. It was, perhaps, this ignoring of practical
utility, so vigorously combated by the pioneers in this country, that
caused Great Britain to be the last of the Great Powers to seriously
take up aircraft for military and naval use. Our delay had been a
wonder to many, since theoretically in the past this nation had been to
the fore. Nearly half a century ago it led the way of the air by being
the first country in the world to found a society for the encouragement
of aërial navigation--the Aëronautical Society of Great Britain. It
is no exaggeration to say that many of the great principles of human
flight were formulated and discussed at the earlier meetings of that
society. The late Mr. Wilbur Wright, when he came to this country to
receive the gold medal of the society, in his speech testified to the
substantial help he had received from the study of the transactions of
the oldest aëronautical society in the world. As the pioneer in laying
the foundations of aërial science, this country is not without honour
amongst the nations.




CHAPTER I

THE EARLIER AËRIAL SCOUTS


Patriotism has been the most powerful factor in developing aërial
navigation. Montgolfier experimented with his paper balloons filled
with heated air in the desire that his invention might be of use to
France in her wars, and throughout the history of both balloons and
flying machines we find that it has been the desire to employ them as
instruments of war that has most fostered their progress.

Very soon after Charles invented the gas balloon the latter was pressed
into military service for the very same purpose of reconnaissance for
which airships and aëroplanes are now being used. At the time of the
French revolutionary war an aëronautical school was founded at Meudon
under the control of Guyton de Morveau, Coutelle, and Conté, and a
company was formed called Aërostiers.

Captive balloons were used by the armies of the Sambre and Meuse, of
the Rhine and Moselle. Just before the battle of Fleurus, 1794, two
ascents were made, and the victory of the French was attributed to
observations made by Coutelle. At that time several ascents were made
from Liége with a spherical balloon and one of cylindrical shape. This
latter appears to have anticipated the well-known German kite-balloon.

There is a tradition that in those early days of the balloon the French
were possessed of a varnish which satisfactorily held the hydrogen gas,
but that the secret was lost--a grave loss indeed, if the tradition has
truth in it. The secret was never refound. A really gas-proof varnish
is unknown.

In the course of the American Civil War of 1861 captive balloons were
again employed with important results.

During the Franco-Prussian War of 1870 three captive balloons were
installed in Paris, the “Nadar” on the Place St. Pierre; the
“Neptune,” manned by Wilfred de Fonvielle, at the gasworks at
Vaugirard; and the “Celeste” on the Boulevard des Italiens.

Thus long before the advent of airships and flying machines the use of
altitude for military reconnaissance was realised. A great disadvantage
of the captive balloon was its stationary nature. It was not prudent to
ascend in it very close to the enemy, as there was not the same chance
of escape as when the aërial observer is in mobile aircraft.

Though rifle fire has over and over again failed to bring down a
captive balloon owing to the upward pressure of the hydrogen gas,
still, artillery fire has been known to have very destructive effect.

Undoubtedly, the best use that has been made of the captive balloon
was in the Boer War. The British observation balloon equipment, which
under the unceasing labours of Colonel Templer had reached a state of
considerable perfection, then proved to be highly efficient. But in
the light of modern aëronautical progress its doings were merely the
foreshadowings of the achievements the aviators in the present war are
daily carrying out.

Perhaps the most important feature of the balloons in the South African
War was the material of which they were made--gold-beaters’ skin. We
are all more or less familiar with this substance, for we use it as
a plaster when we cut our fingers. We should scarcely think that so
apparently fragile a substance was strong enough to form the envelope
of a balloon. It is, however, an admirable substance for the purpose
on account of its lightness and capacity of holding the gas, and the
desideratum of strength can be obtained by combining layer and layer
of the substance to any desired thickness. By the use of gold-beaters’
skin it became possible to have much smaller balloons for a given
lifting power than when varnished cambric or silk was employed. If
made of the latter materials a captive observation balloon had to be
at least 18,000 cubic feet to be of any service. Gold-beaters’ skin
reduced the volume to 10,000 cubic feet, or even less.

The only disadvantage of gold-beaters’ skin for the envelope of
balloons and airships appears to be its very great expense. This, in
the case of a large airship, is formidable. It should be mentioned,
however, that it has sometimes been used for the separate gas
compartments which, as will be seen, are a feature of the Zeppelin
airship.

As regards the actual achievements of the balloon in South Africa,
one section did excellent work at Ladysmith. In the words of Colonel
Templer, “it not only located all the Boer guns and their positions,
but it also withdrew all the Boer fire on to the balloon. Several
balloons were absolutely destroyed by shell fire.”

One of the balloons was burst at a height of 1,600 feet, and came down
with a very quick run, but the staff officer in the car was unhurt. At
Ladysmith, by means of the balloon, the British artillery fire was made
decisive and accurate.

With General Buller at Colenso, and up the Tugela River, Captain
Philips’ balloon section was very useful. Splendid work was done at
Spion Kop. There the whole position was located and made out to be
impregnable. It has been said that the British Army was then saved from
falling into a death trap by the aërial reconnaissance. Captain Jones’
section went up with Lord Methuen on Modder River. His observations
continued every day. It was considered there was not a single day that
they were not of the utmost importance.

Again, Lord Kitchener and Lord Roberts used balloons. From the
information they obtained from them they were enabled to march on to
Paardeburg. At the latter place itself they were able to locate the
whole position. Another section went to Kimberley and on to Mafeking.
A very important observation was made at Fourteen Streams. There a
balloon was used continuously for thirteen days without the gas being
replenished. By its means the Boers were prevented from relieving
Fourteen Streams.

It has been pointed out by Colonel Templer that one of the great
difficulties connected with the use of the comparatively small balloons
in the South African War was the heights the armies went over.

    On the march to Pretoria there were hills 6,000 feet above the
    sea, and to make an observation from these hills it was necessary
    to go up 1,500 or 2,000 feet, so that the barometrical height was
    hard work on the buoyancy of the balloon, because the barometrical
    height then became 8,000 feet--the 6,000 feet altitude above the
    sea-level, and the 2,000 feet it was necessary to go over the
    hills--that was about all our balloons would do.

That was a disadvantage of the captive balloons which would not have
been felt if the observers had been on aëroplanes!

Certainly, the excellent gas retaining power of gold-beaters’ skin
was well put to the test in the South African War. The thirteen days’
work with one charge of gas mentioned above was a fair trial for a
balloon of such comparatively small size; but Captain H. B. Jones gave
a still more striking experience of the value of gold-beaters’ skin as
a gas-holder. Speaking of the Bristol war balloon of 11,500 cubic feet
capacity, he says:--

    It was used at the engagements at Vet River and Land River,
    and arrived at Kroonstad on May 12th. The balloon was kept in a
    sheltered place near the river till we marched again, on May 22nd,
    and was not emptied till after we had crossed into the Transvaal
    at Vereeniging on May 27th. To keep a balloon going for thirteen
    days at one station is a good test; but in our case the Bristol was
    filled for twenty-two days, and did a march of 165 miles with the
    division.

The system of filling the balloons from steel cylinders in which the
hydrogen gas had been compressed, so well exemplified in the Boer War,
was a great improvement on the older methods of manufacturing the gas
on the spot. Speed in filling balloons is a desideratum for their use
in war. By the cylinder method, owing to the great pressure under which
the gas escapes from the cylinder, the inflation of the observation
balloons became a question of minutes instead of hours. The necessity
of speed applies to the inflation of airships also.

Although the present volume is designed rather to speak of the
aëronautical appliances of the present than those of the past, the
above-mentioned facts concerning aërial reconnaissance in the Boer War
have been included, as the value of the air scouts at the time was
hardly known and appreciated by the general public, whose mind in those
days was not constantly being directed to aërial matters as it is at
the present time. The knowledge of what just a few well-contrived and
well-utilised balloons could then do in the way of aërial scouting
must lead to the thought how the Boer War might have been shortened
had we then possessed the squadrons of fast-flying aëroplanes that are
taking part in the present war. To know, indeed, what a very few aërial
observers could do may enhance our estimation of the possibilities of
the squadrons of the flying machines of the British and allied armies
in the present war as they dart in search of information over the lines
of the enemy.

In the course of some articles on the subject of the new arm of war,
which contain many apt statements, Mr. F. W. Lanchester gives the
opinion that the number of aërial machines engaged in the war is a
negligible quantity. We might, indeed, well say the more the better,
provided they are on the Allies’ side; but no aëronaut or aviator
will allow the number is negligible. The writer compares the supposed
number of aëroplanes the Germans possess with the cost equivalent of
scouting cavalry. The comparison is not a happy one, on account of
the tremendous advantage of altitude and, consequently, long range of
vision possessed by the aërial scout. We have seen that in the Boer War
one observer at Spion Kop from his height and super-sight saved the
situation, and rescued our army from possible crushing disaster.

What might not even one shrewd British observer in a swift-moving
modern aërial craft accomplish at a critical moment in the present
conflict?




CHAPTER II

THE DEVELOPMENT OF THE AIRSHIP


Before free balloons were successfully motor driven and steered, stern
necessity had pressed them into the service of war. During the siege
of Paris, in 1870, when the Parisians were cut off from all means of
escape, there were only a few balloons in Paris; but the successful
escape of some aëronauts in them was considered encouraging enough to
establish an aërial highway involving a more wholesale manufacture
of balloons than had been accomplished before. The disused railway
stations were converted into balloon factories and training schools for
aëronauts. In four months sixty-six balloons left Paris, fifty-four
being adapted to the administration of post and telegraph; 160
persons were carried over the Prussian lines; three million letters
reached their destination; 360 pigeons were taken up, of which only
fifty-seven came back, but these brought 100,000 messages, by means of
microphotographical despatches. In these a film 38 by 50 mm. contained
2,500 messages. The pigeons usually carried eighteen films, with 40,000
messages.

At this time the French Government attempted to produce a navigable
balloon, and employed Dupuy de Lôme on the task of designing and
building it. This was to be driven by hand power, the screw being
driven by eight labourers. The balloon was actually made and tested.
Considering the h.p. was 0.8, it is needless to say it was not
successful.

It was during the siege of Paris that Krupp constructed the first
special gun for attacking balloons, a relict which has been preserved
at Berlin.

If such was the utility of balloons that merely drifted at the mercy
of the aërial currents they encountered, it was not to be wondered
at that, soon after the Franco-Prussian War, new attempts were made
to make them navigable. Though the term airship might reasonably be
applied to all the forms of navigable aircraft still in this country,
it has been applied in a less wide sense to those machines that
are lighter than air. In these pages the term will be used in this
connection.

The effort to navigate balloons almost dates back to the invention of
the balloon itself. It was, indeed, early realised that the spherical
shape of the ordinary balloons that drift with the winds would be
unsuitable for a craft that would have to travel against the wind. In
1784 Meusnier designed an elongated airship, in which the brothers
Robert actually ascended. It is noticeable that in this early design of
Meusnier was the now well-known ballonet, or inner balloon, which forms
an essential feature of modern non-rigid and semi-rigid airships for
preserving the rigidity of the outer envelope and facilitating ascent
or descent.

If we except the effort of Dupuy de Lôme, the next remarkable attempt
at airship construction was in 1852, when the Parisian Giffard made his
steam-driven elongated balloon, with which he made two experiments.
These merely proved that successful navigation against a wind would
require much larger motive power than his Lilliputian steam-engine of 3
h.p. Giffard, however, was the pioneer of the airship driven by other
than hand power. The following are the dimensions, etc., of what will
ever be an historic balloon:--

  Length                      44 metres
  Diameter                    12.00 metres
  Cubic capacity              2,500 cubic metres
  Horse power                 3.0
  Estimated speed per hour    6.71 miles

The experiments of Krebs and Renard in 1885 were noteworthy. They were
the first in which direct return journeys were made to the place whence
the balloon started.

These experiments showed the importance of the military factor in the
development of aërial navigation. Krebs and Renard were the officers
in charge of the French Military Aëronautical Department at Meudon,
and they applied national funds to the construction of an airship. It
was the development of the electrical industry and the production
of electric motors at that time which stimulated the experiments.
The brothers Tissandier had, in 1883, propelled an elongated balloon
against a wind of some three metres a second by means of an electric
bichromate battery which supplied the power to an electric motor. It
was thought that those experiments had been sufficiently successful for
further trial of the powers of electricity.

Renard made profound and exhaustive researches into the science of the
navigable balloon. To him we are, indeed, indebted for the elucidation
of the underlying principles that have made military airships possible.

The navigable balloon “La France” was dissymmetrical, being made very
much in the shape of a fish or bird. Its master diameter was near the
front, and the diameters diminished gradually to a point at the back.

The following were the dimensions of the envelope:--

  Length                 50.40  metres
  Diameter                8.40  metres
  Length in diameters     6.00  metres

The airship was remarkably steady on account of the minute precautions
taken to counteract the instability produced by a somewhat excessive
length. Any device which modifies pitching at the same time lessens
the loss of speed resulting from the resistance of the air when the
ship is moving at an angle. A direct means of reducing pitching is
the dissymmetrical form given to the envelope by placing the master
diameter near the front. The resistance of the air falls on the front
surface, which in this dissymmetric form of envelope is much shortened,
while the compensating surface at the back is augmented. Many experts
are of opinion that in this form of envelope Krebs and Renard came
nearer perfection than any other navigable balloon constructor.

Like the brothers Tissandier, they used an electric battery and motor
to drive their screw, their motive power being 9 h.p.

It was claimed that out of seven journeys, the airship returned five
times to the place whence it started. As an example of these journeys,
on September 22nd, 1885, a journey was made from Meudon to Paris and
back again. On this day the wind was blowing at a velocity of about
3.50 metres a second--what we should call a calm. Few, perhaps, who saw
the small naval airship, the “Beta,” manœuvring over London this autumn
realised that a navigable balloon, not so very much unlike it in form,
was speeding its way over Paris as long ago as 1885. The advent of
the first at all practical military airship was forgotten because the
experiments, comparatively successful as they were, suddenly ceased.
They came to an end because it was found that though electricity as a
motive power could afford an airship demonstration, it was unfitted for
serious and prolonged use.

One industry has often to wait for another--the world had to wait for
the missing link in aërial navigation. That was the light petroleum
motor. With its coming came the era of airships and aëroplanes.




CHAPTER III

TYPES OF MODERN AIRSHIPS


With the new century came the modern military airship--to stay, at any
rate, until the heavier-than-air principle of aërial navigation has so
developed as to absorb those features of utility the airship has and
the aëroplane has not.

During the fourteen years which have seen the construction of practical
airships, three distinct types have been evolved--(i.) rigid, (ii.)
non-rigid, (iii.) semi-rigid. In considering the airships of Great
Britain, France, and Germany, I propose to class them together as to
types rather than under nationalities.

Each type has its own peculiar advantages. The choice of type must
depend upon the circumstances under which it is proposed to be
employed.

[Illustration: Top: SNAPSHOT OF ZEPPELIN IN MID-AIR.

Centre: MILITARY LEBAUDY AIRSHIP, showing fixed vertical and horizontal
fins at the rear of gas-bag, vertical rudder, and car suspended from
rigid steel floor underneath gas-bag.

Bottom: CAR OF A LEBAUDY AIRSHIP, showing one of the propellers.]


I. RIGID TYPE.

(i.) _Zeppelin_ (German).--There are not many examples of the rigid
type. The most important is undoubtedly the Zeppelin. This form of
airship before the present war had elicited the interest of the
aëronautical world for the long-distance records it had established.
Indeed, no little sympathy had been extended to Count Zeppelin for his
perseverance in the face of the gravest difficulties. Now the Zeppelin
has accumulated notoriety instead of fame as having been the means of
carrying on a form of warfare repugnant to the British nation, and
condemned by the Hague Convention. Imagine some seventeen huge bicycle
wheels made of aluminium, with their aluminium spokes complete, and
these gigantic wheels to be united by longitudinal pieces of aluminium,
and in this way seventeen sections to be formed, each of which contains
a separate balloon, and it is easy to grasp the construction of the
Zeppelin airship. It consists of a number of drum-shaped gas-bags,
all in a row, held together by a framework of aluminium. They form
a number of safety compartments. The bursting of one does not
materially matter--the great airship should still remain in the air.
The dimensions of individual Zeppelins have varied to some extent. The
largest that has been built (“Sachsen,” 1913) had a cubic capacity of
21,000 cubic metres (742,000 cubic feet), and a length of 150 metres
(492 feet). The aluminium framework containing the balloons has an
outer covering of cloth. On each side of the frame of the airship
are placed two pairs of propellers. In the original airship of 1900
these were four-bladed, and made of aluminium. They were small, being
only 44 inches in diameter, but they revolved at a very high speed.
In the later airships the screws have been considerably modified in
detail, size, and shape. For instance, in the Zeppelin which descended
accidentally at Lunéville, in France, it was found that the back
pair of the propellers on each side were four-bladed, the front pair
two-bladed. The screws are driven by motors placed in the two aluminium
cars beneath the airship. These cars are connected by a covered
gangway, which also serves as a track for a movable balance weight,
by means of which a considerable change of balance can be effected.
The motive power in the first Zeppelin was only two Daimler motors of
16 horse power each. With this low power little success was attained,
but gradually the motive power has been increased. We find that in the
naval Zeppelin, L 3, 1914. The motive power is three Maybach motors,
giving total h.p. 650, whereas in the types building the total h.p. is
800.

The stability of these aërial monsters is attained by the use of large
projecting fins. Horizontal steering is effected by a large central
rudder and pairs of double vertical planes riveted between the fixed
horizontal stability planes. For vertical steering there are sixteen
planes provided in sets of four on each side of the front and rear
ends of the balloons. These can be independently inclined upwards or
downwards. When the forward ones are inclined upwards and the after
planes downwards, the reaction of the air on the planes as the airship
is driven forwards causes the front part to rise and the rear part
to sink, and the airship is propelled in an inclined direction to a
higher level. The favourite housing place for the Zeppelin airships
has in the past been on Lake Constance, near Friedrichshafen, so that
they could be taken out under protection from the direction of the
wind. It is also much safer for large airships to make their descent
over the surface of water. It has been estimated that the most powerful
Zeppelins have a speed of some fifty miles an hour.

When on April 3rd, 1913, Z 16, in the course of a journey from
Friedrichshafen, was forced to descend on French soil at Lunéville,
excellent opportunity was afforded the French of a close inspection of
its details.

The following were the exact dimensions, etc.:--

  Length                        140 metres
  Diameter                      15 metres
  Cubic capacity                20,000 metres
  Motive power three Maybach
    motors, 170 h.p. each       510 h.p.
  Speed                         22 metres per sec.
  Height attainable             2,200 metres
  Useful carrying power         7,000 kilos.

On the top of the ship was a platform, on which a mitrailleuse could be
mounted.

It was only a few weeks before the present war that the new Zeppelin,
L Z 24, attained a new world’s record of altitude and duration of
flight. The height attained was 3,125 metres. The voyage without a
break lasted thirty-four hours fifty-nine minutes. On May 22nd, 1914,
it left Friedrichshafen at 7.16 a.m. Bâle was reached at 10 a.m. At 6
p.m. it passed Frankfort, at 9 Metz, at 10.30 Bingen, at 2 a.m. Brême.
At 4 a.m. it arrived above Heligoland, from whence it made for Potsdam,
where it was hailed 9.20 a.m. At 5.15 p.m. it landed at Johannisthal.

That journey certainly showed the long-range powers of the latest
Zeppelins. If, as will be seen, it is comparatively easy for a few
well-directed aëroplanes to wreck them in mid-air, still they have
ceased to be military or naval playthings.

(ii.) _Schutte-Lanz_ (German).--The Schutte-Lanz rigid airship is
an attempt to secure the advantages of the rigid type without the
fragilities of the Zeppelin. The framework, which contains the
separate gas compartments, is made of fir wood. The gas-bags are
claimed to be very strong. These are filled, excepting two, which
remain empty when there is only sea-level pressure; when, however,
the gas expands, it flows into the latter. These become full when
an altitude of some 2,000 metres is reached. A centrifugal pump is
employed for distributing the gas.

The volume of this airship is 26,000 cubic metres (918,000 cubic feet).
It will be seen, therefore, that this mammoth airship in size surpasses
even the largest Zeppelins.


II. SEMI-RIGID.

(i.) _Lebaudy_ (French).--This airship is a crossbreed between
the rigid and non-rigid systems. By this method of construction a
considerable amount of support can be imparted to the gas-bag, though
it does not dispense with the services of the ballonet, as does the
entirely rigid type. To the genius of M. Julliot, Messrs. Lebaudy
Brothers’ engineer, we are indebted for the introduction of this
excellent type. It no doubt forms an exceedingly serviceable military
airship. In the Lebaudy original airship the underside of the balloon
consisted of a flat, rigid, oval floor made of steel tubes; to these
the stability planes were attached, and the car with its engine and
propellers was suspended. This secured a more even distribution of
weight over the balloon. The gas-bag was dissymmetrical in form. Though
not exactly resembling that excellent pattern, “La France,” it partook
of the important quality of having the master diameter near the front.
The car was a steel frame, covered with canvas, and in the form of a
boat. The screw propellers were placed on either side of the car.

In 1909, as the British Government at that time possessed only very
small airships, the nation raised a sum of money by subscription
to present the Government with one of efficient size. The military
authorities compiled a list of somewhat severe tests which, in their
opinion, they thought an airship should be able to perform before
acceptance. At the request of the Advisory Committee, of which Lord
Roberts was chairman, the writer went to France in an honorary capacity
to select the type of airship to be adopted. There was at that time
only one firm of airship makers in France who were willing to undertake
the formidable task of making an airship that would come up to the
requirements of the British Government--the brothers Lebaudy, whose
engineer and airship designer was M. Julliot.

The semi-rigid airship which M. Julliot designed and executed was
without doubt a _chef d’œuvre_ of its kind. The rigid tests it had to
undergo necessitated a modification of some of the details that were
conspicuous in the airships the constructor had previously built.

In this airship the girder-built underframe was not directly attached
to the balloon, but suspended a little way beneath it.

The gas envelope had a cubic capacity of 353,165.8 cubic feet; the
length was 337¾ feet. There were two Panhard-Levasseur motors of 135
h.p. each.

On October 26th, 1910, this airship made an historic and record flight
over the Channel from Moisson to Aldershot in five hours twenty-eight
minutes, at a speed of some thirty-eight miles an hour, sometimes
against a wind of twenty-five miles an hour. Unfortunately, owing to a
miscalculation by those responsible, the shed which had to receive the
new airship on its arrival was made too small to house it safely. While
the airship was being brought into the shed its envelope was torn and
placed _hors de combat_.

Since this airship was made the Lebaudy brothers have ventured to still
further increase the size of their semi-rigid airships.

(ii.) _Gross_ (German).--This airship may be described as being more or
less a German reproduction of the Lebaudy type. It forms part of the
German airfleet. A considerable number have been made of various sizes
(for dimensions, etc., see table, German Airships, Chapter IV., page
38).

III. NON-RIGID.

This type is dependent for its maintenance of form on the pressure of
the gas inside the envelope. It is all-important that the envelope of
a navigable balloon should not lose its shape--that it should be kept
distended with sufficient tautness, so that it may be driven through
the air with considerable velocity. On this account the non-rigid type
depends entirely on the ballonet system, which consists of having
one or more small balloons inside the outer envelope, into which air
can be pumped by means of a mechanically driven fan or ventilator to
compensate for the loss of gas from any cause. The ballonets occupy
about a quarter of the whole volume of the envelope. Such a type is
exceedingly well suited for the smaller-sized airships, destined
rather for field use than long-range offensive service. Such airships
are quickly inflated and deflated. They are also easily transported.
Even the Lebaudy or Gross semi-rigid types, though not so clumsy or
difficult of transport as the Zeppelins, require more wagon service
than the absolutely non-rigid.

[Illustration: PARSIFAL AIRSHIP LEAVING ITS HANGAR.]

[Illustration: PARSIFAL AIRSHIP, showing one of the fixed horizontal
planes, steering rudder, and car.]

The British Government have evolved several non-rigid airships of
moderate dimensions which have been exceedingly useful as _ballons
d’instruction_. For obvious reasons it is not desirable that
particulars concerning them should be published at the present crisis.

(i.) _Parsifal_ (German).--Very numerous examples of non-rigid airships
could be cited, but it will suffice now to mention two, the German
Parsifal and the French Clement-Bayard. The Parsifal is the only type
that the German nation has allowed to be supplied to foreign countries.
For instance, our Navy possesses one. It has also been supplied to
Austria, Italy, Russia, and Japan. On account of its portability it
is perhaps the most generally useful type of airship that has been
designed, if we exclude long-range service. It has been exceptionally
free from accidents on account of its subtleness. The originator of the
Parsifal seems to have thoroughly grasped the sound idea that to attain
success in navigating a subtle medium like air the machine should be
correspondingly subtle--as, indeed, are the animal exponents of flight.

In the Parsifal the exclusion of the element of rigidity has been
carefully studied. All that is rigid about it is the car and motor,
and this can be conveyed in one cart.

The size of the Parsifals has been advisedly limited. The majority of
them are not more than a third of the cubic capacity of the Zeppelins.
A distinctive feature is the distance of the car from the gas-bag. This
in the first types constructed was nine metres, though in more modern
forms the figure is less. Owing to the distance of the car from the
main body the attaching cords are distributed with equal tension over
the whole length of the envelope. In the Parsifal airships there are
two ballonets, one at the front and one at the back of the gas-bag.
They are not only used for keeping the envelope rigidly expanded, but
also to facilitate rising and falling, air being admitted into the one
and expelled from the other, as the case may be. Another distinctive
feature is the four-bladed propellers. These have fabric surfaces,
and are weighted with lead. When at rest the blades are limp, but in
revolving, owing to centrifugal force, they become endowed with the
necessary rigidity. The dimensions of the Parsifals vary considerably,
the smallest made had a capacity of 3,200 cubic metres (1908), the
largest more recent ones have a capacity of 11,000 cubic metres. A
very useful size is the P L 8 (1913), station Cologne, of which the
dimensions are:--

  Length         77 metres
  Diameter       15.50 metres
  Volume         8,250 cubic metres
  Total lift     5½ tons
  Motors         300 h.p. (Daimler 150 h.p. each)
  Speed          41 miles per hour

(ii.) _Clement-Bayard._--It is a question whether it is advisable to
extend the non-rigid system to the amount that has been latterly done
in the case of such a construction as the Clement-Bayard. This type of
French airship is familiar to many in this country, as it was the first
airship to cross the Channel from France to England.

The cubic capacity of this airship was 6,300 cubic metres. A feature
was the comparatively large size of the ballonet used. To realise how
the Clement-Bayards have grown since this type of airship came to this
country, see table, French Military Airships, page 34.

_Astra-Torres Type._--The Astra-Torres airships may be said to form a
rather special subdivision of the non-rigid class, for, though there
is no rigid metal in its construction, an unbendableness of keel is
assured by panels of cloth so placed horizontally as to be kept rigid
by the pressure of the air in a ballonet. Thus the virtue of rigidity
is attained without the extra weight generally appertaining thereto,
and a greater speed with economy of weight and size. The British naval
authorities possess one of these airships. For dimensions, etc., of the
latest Astra-Torres airships, see table, French Military Airships, page
34.

It will have been seen from the above short descriptions of distinctive
types of airships Germany is the only nation which makes a very marked
feature of retaining the rigid form. It is true France has evolved one
form of rigid, the Spiess, in which the framework is made of wood,
but she undoubtedly has a preference for the semi-rigid and non-rigid
types. The rigid type has not found much favour in Great Britain.

Reckoning from the year 1911, France appears to have nineteen
military dirigibles, and she may have one or two older ones in
repair. Some of these are building; and as in France there are many
eminent aëronautical factories, there are always also a number of
private airships built, or in building, of various sizes and various
types. These firms have enormous private airship hangars, and every
convenience for making, filling, and storing. The number of military
hangars in France is seven, at the following towns: Epinal, Maubeuge,
Belfort, Rheims, Toul, and Verdun, where there are two.

In the spring of 1913 the Italian military dirigible fleet consisted of
two units of Series M--M1 and M2--dirigibles of 12,000 cubic metres,
and three units building of Series M--M3, M4, and M5.

These dirigibles of the M series were found in practice to be the most
successful; they attained a speed of 70 kilometres per hour, and a
height of 2,000 metres; they are all semi-rigid. The Italian Government
is ambitious of rivalling in its aëronautical fleet that of Germany,
and decided in that year, 1913, on a new series--Series G. These
were to be of 24,000 cubic metres, and to travel at a speed of 100
kilometres the hour.


AIRSHIPS.

 ----+-----------------------+------------+----------+--------+-----+------
     |                       |            |          |Capacity|     |Speed
     |         Name.         |   Maker.   |   Type.  |  Cub.  | H.P.|m.p.h.
     |                       |            |          | Metres.|     |
 ----+-----------------------+------------+----------+--------+-----+------
 1911|Adjutant Reau          |    Astra   |Non-rigid | 8,950  |  220|  32
     |Lieut. Chaure          |    Astra   |Non-rigid | 8,850  |  220|  32
     |Le Temps               |  Zodiac 9  |Non-rigid | 2,300  |   50|  29
     |Capt. Ferber           | Zodiac 10  |Non-rigid | 6,000  |  180|  33
     |Capt. Marécahl         |  Lebaudy   |Semi-rigid| 7,500  |  160|  28
     |                       |            |          |        |     |
 1912|Adjutant Vincennot     | C. Bayard  |Non-rigid |  --    |  -- |  --
     |Dupuy de Lôme          | C. Bayard  |Non-rigid |  --    |  -- |  --
     |Selle de Beauchamp     |  Lebaudy   |Semi-rigid| 8,000  |  160|  28
     |Éclaireur Conté        |    Astra   |Non-rigid | 9,100  |  -- |  28
     |                       |            |          |        |     |
 1913|E. Montgolfier         | C. Bayard  |Non-rigid | 6,500  |  150|  36
     |Comot Coutelle         |   Zodiac   |Non-rigid | 9,500  |  360|  37
     |Fleurus                |  Military  |Non-rigid | 6,500  |  160|  40
     |                       |   Factory  |          |        |     |
     |Spies                  |   Zodiac   |Rigid     |16,400  |  400|  43½
     |                       |            |          |        |     |
 1914|[A]Clement-Bayard VIII.| C. Bayard  |Non-rigid |23,000  |1,000|  47
     |[A]Clement-Bayard IX.  | C. Bayard  |Non-rigid |23,000  |1,000|  47
     |Astra-Torres XV.       |   Astra    |Non-rigid |23,000  |  800|  43
     |Astra-Torres XVI.      |   Astra    |Non-rigid |23,000  |  800|  43
     |Zodiac XII.            |   Zodiac   |   --     |23,000  |1,000|  50
     |Zodiac XIII.           |   Zodiac   |   --     |23,000  |1,000|  50
 ----+-----------------------+------------+----------+--------+-----+------

  [A] These two carry each one gun.

At the present moment Italy is building some very large airships, some
even bigger than the Zeppelin, and she practises ascents diligently
with those she has. One of the new airships building for the Italian
navy is a Parsifal of 18,000 cubic metres.

Great attention is paid in Russia to aëronautics. The Russians have
no national types of dirigibles or aëroplanes yet developed; but they
manufacture in their own country.

They have thirteen dirigibles (one is rumoured to be destroyed),
semi-rigid and non-rigid, amongst them a Lebaudy made in 1910,
Parsifals of 1911 and 1913, an Astra of 1913. The Parsifal of 1913 has
a speed of 43–68 m.p.h. (km.).

Formerly Austria-Hungary led the way in aëronautics amongst the nations
of the Triple Alliance. Germany particularly looked to her for flying
machines, and the first Etrichs were hers; but military aëronautics in
Austria-Hungary are now at a low ebb.

The decline is ascribed to monopoly and centralisation. At the present
moment Austria has one dirigible, in a feeble condition, and about
ten aëroplanes of foreign make. Two German houses, the Albatross and
D.F.W., have quite lately opened branches in Austria.

The dual monarchy began well; in 1909 she had a small Parsifal, in 1910
a Lebaudy, in 1911 the Körting. These three perished in accidents. Her
own system, the Boemches, presented to her by a national subscription,
failed in speed; but though she has no dirigibles to inhabit them she
has three good hangars!

Belgium has three airships, all non-rigid--two Godards and one Astra.
Although not of very late construction, all three have innovations and
interesting features. The Astra is private property.

[Illustration:

                                                     [_Topical Press._
  ZEPPELIN AIRSHIP AT COLOGNE,

showing at the rear large vertical rudder, and two pairs of vertical
rudders for horizontal steering, the horizontal planes at the sides for
vertical steering, two of the four propellers at side of airship, car
beneath airship.]




CHAPTER IV

THE GERMAN AIRSHIP FLEET


Many reports have been current concerning the exact dimensions of the
airship fleet that Germany can put into action. It has been said that
she has been extremely active since the beginning of the present war
in adding fresh units to the forces she had available when the war
broke out. It has also been rumoured that she is making a new type of
Zeppelin--one much smaller, and which will have greater speed than the
larger type.


GERMAN AIRSHIPS IN THE SPRING OF 1913.

  -------------------+--------+-----------------------------------
                     |        |           Motive power.
                     | Volume +-----+----------+----------+-------
        Type.        |   m.   |     |          | h.p. per |  Max.
                     |        | No. |  Type.   |  Motor.  | Speed.
                     |        |     |          |          |  m/s
  -------------------+--------+-----+----------+----------+-------
  Zeppelin           | 17,700 |  3  | Maybach  |   150    |  21
  Zeppelin           | 18,700 |  3  |    --    |   150    |  21.1
  Zeppelin           | 18,700 |  3  |    --    |   150    |  22
  Zeppelin           | 18,700 |  3  |    --    |   150    |  22
  Zeppelin           | 22,000 |  3  |    --    |   150    |  --
  Zeppelin           | 20,000 |  3  |    --    |   170    |  --
  Zeppelin           | 18,700 |  3  |    --    |   170    |  --
  Zeppelin           |   --   | --  |    --    |    --    |  --
  Parsifal           |  4,000 |  1  | Daimler  |    85    |  14
  Parsifal           |  7,500 |  2  |  N.A.G.  |   110    |  15
  Parsifal           |  8,000 |  2  | Maybach  |   180    |  18.8
  Parsifal           | 10,000 |  2  | Koerting |   200    |  18.5
  Parsifal           |  8,000 |  2  |  N.A.G.  |   110    |  16
  Parsifal           | 10,000 |  4  | Maybach  |   180    |  --
  Siemens-Schückert  | 15,000 |  4  | Daimler  |   125    |  19.8
  Schutte-Lanz       | 19,500 |  2  | Daimler  |   270    |  20
  (1) Gross-Basenach |  5,200 |  2  | Koerting |    75    |  12.5
  (2)       --       |  5,200 | --  |    --    |    75    |  12.5
  -------------------+--------+-----+----------+----------+-------

    (1) and (2) as in 1911; since then they have been renovated,
    and no doubt their speed and volume are much greater.

We must accept with some reserve the reports that are current in this
respect, and it may be pointed out that in accounts of the doings of
Zeppelin airships in the papers it can be reasonably doubted whether
all the Zeppelins mentioned are in reality Zeppelins. Probably some are
the smaller types, such as the Gross or Parsifal. The word Zeppelin
seems to have become synonymous with a German airship, and the wounded
soldiers or prisoners who are responsible for many of the stories told
would not be likely to have complete knowledge of the distinctions
between classes of airships.

Though what Germany is exactly doing in way of new manufacture
must remain in much fog, still we can form some opinion as to her
preparedness with aircraft on the lighter-than-air principle from our
knowledge of what she possessed last year.

The table on the opposite page will show that her fleet of airships,
including those under construction, was then by no means negligible.

A nation possessing such a fleet of large airships as Germany does must
be provided with sheds (hangars) for their reception in all parts of
the country, and by the table that is appended it will be seen that in
this way last year Germany was very amply provided.

I am indebted to the _Aérophile_ for the following list of German
hangars for dirigibles, with dates of construction and names of
owners:--

 -------------------------+--------------------------+------------------
    Place and Date of     |       Proprietors.       |   Observations.
      Construction.       |                          |
 -------------------------+--------------------------+------------------
 Aix-la-Chapelle          |            --            | Designed for 1914
 Allenstein               |            --            | Designed for 1914
 Baden--Baden-Dos (1910)  |            --            |         --
 Berlin--Biesdorf (1909)  |       Siemens and        |
                          |        Schückert         |         --
 Berlin--Reinickendorf    |            --            |         --
 Berlin--Johannisthal     |       Aëronautical       |
   (1910)                 |      Sport Society       |         --
 Berlin--Johannisthal     |                          |
   (1911)                 |            --            |         --
 Berlin--Tegel (1905)     |      Prussian Army       |         --
 Berlin--Tegel (1907)     |      Prussian Army       |         --
 Berlin--Tegel (1908–10)  |      Prussian Army       |         --
 Bitterfeld (1908)        |       Luffahrtzeug       |         --
                          |         Society          |
 Bitterfeld (1909)        |       Luffahrtzeug       |         --
                          |         Society          |
 Braunschweig             |     Airship Harbour      | Designed for 1914
                          |   Society of Brunswick   |
 Cologne                  |            --            |         --
 Cologne--Leichlingen     |        Rheinwerke        |         --
                          |     Motorluftschiff      |
                          |         Society          |
 Cologne--Nippes          |          Clouth          |         --
 Cuxhaven                 |       German Navy        | Designed for 1914
 Dresden                  |     City of Dresden      |  Will only hold
                          |                          |    one balloon
 Düsseldorf (1910)        |    City of Düsseldorf    |         --
 Cologne--Bickendorf      |                          |
   (1909)                 |      Prussian Army       |         --
 Frankfurt am Main        |                          |
   (1911)                 |          Delay           |         --
 Friedrichshafen (1908)   |     Zeppelin Society     |         --
 Friedrichshafen--Manzell |     Workshops of the     |         --
   (1900)                 |     Zeppelin Society     |
 Gotha (1910)             |      Town of Gotha       |         --
 Graudenz                 |            --            | Designed for 1914
 Hannover                 |            --            | Designed for 1914
 Hamburg--Fuhlsbüttel     |     Hamburg Airship      |
   (1911)                 |     Harbour Society      |         --
 Hamburg--Hansa           |            --            |         --
 Kiel (1910)              | Union for Motor-Airship  |         --
                          |          Travel          |
 Königsberg-in-Preussen   |                          |         --
   (1911)                 |      Prussian Army       |
 Leehr                    |            --            | Designed for 1914
 Leipzig                  | Leipziger Luftschiffland |         --
                          |  Flugplatz Gesellschaft  |
 Liegnitz (1913)          |      Prussian Army       |  In construction
 Mannheim--Schwetzinger   |            --            |         --
 Mannheim--Rheinau        |      Luftschiffbau       |
   (1909)                 |     Schütte u. Lanz      |         --
 Metz (1909)              |      Prussian Army       |         --
 Potsdam, near Berlin     |     Zeppelin Society     |
   (1911)                 |            --            |         --
 Posen                    |            --            |    Constructing
 Schneidemühl             |            --            |      Building
 Strasbourg               |      Prussian Army       |         --
 Thorn (1912)             |            --            |         --
 Trèves                   |            --            |      Building
 Waune (1912)             |   Rhenish-Westphalien    |         --
                          |          Flying          |
                          |     and Sports Club      |
 -------------------------+--------------------------+------------------

Such monster airships as the Zeppelin call for a large proportion
of pure hydrogen. This is, indeed, manufactured on a large scale in
Germany. It is produced in quantities by the electro-chemical works
at Bitterfeld, Griesheim, and at Friedrichshafen, specially for the
needs of the Zeppelins at the latter place. There are also works for
the production of very pure hydrogen by electrolysis at Bitterfeld,
Griesheim, Gersthofen, and Dresden.

In the particular way Germany means to use her lighter-than-air fleet
in the present war time will show. If, however, there have not yet
been attempts at any combination of action, individual Zeppelins have
already played the rôle of dreadnoughts of the air. Though their powers
have been no doubt exaggerated, they have been the terror of some
Belgian cities.

Early in the morning of August 25th a Zeppelin airship visited Antwerp,
and drifting silently with the wind steered over the temporary Royal
palace. There it discharged six highly explosive bombs. Not one found
its intended mark, though all fell near the palace. One appears to
have been very near hitting the tower of the cathedral. Though the
bombs failed to attain the object sought, no less than six or seven
persons were victims to the outrage. One struck a private house,
killed a woman, and injured two girls, killed two civic guards, and
wounded another. One bomb fell in the courtyard of the hospital of St.
Elizabeth, tore a hole in the ground, smashed the windows, and riddled
the walls.

The Zeppelin repeated its visit early in the morning of September 2nd,
but this time with less deadly result. The bombs only wounded the
victims. The experiences of the first visit had given effective warning
against a repetition of aërial invasion. The city had been darkened,
and the airship was attacked from the forts and the high points of the
city as soon as it made its appearance. The crew of the airship seem to
have been struck with panic when it failed to find its bearings over
the darkened city.

It appears they suddenly dropped all their bombs as ballast and rose
quickly out of harm’s way. The bombs used on this occasion were not
of the same type as those used on the previous attempt on the city.
The latter were of high explosive power designed to destroy buildings.
The former were covered by thin envelopes, and held together by
mushroom-shaped rivets. They were filled with iron bolts and nuts, and
were evidently designed for the destruction of human life. It is stated
that this is a type of bomb which has never been used by artillery,
being made on the same model as that used by the notorious French
robber, Bonnet.

In reference to airship raids over cities, it has been suggested in
America that the air in their immediate neighbourhood should be mined.
This could be done by having a number of captive balloons or kites,
the mines on which could be discharged electrically from the ground.
For future wars there will no doubt be devised some form of travelling
aërial torpedoes for destroying the intruding airships. Such torpedoes
would, however, have to be capable of guidance. As has been pointed
out by Mr. W. F. Reid, in 1884, at the siege of Venice, the Austrians
used free balloons for the purpose of dropping bombs upon the town.
The bombs were attached to the balloons in such a way that after the
burning of a certain length of safety fuse, the connection was severed,
and the bomb fell. The length of fuse was calculated according to the
speed of the wind; but, unfortunately, when the balloons rose, they
entered an upper air-current travelling in a different direction from
that below, and many of the bombs burst in the Austrian lines, whence
they had started. Thus it would not be expedient to let loose ordinary
unmanned balloons loaded with timed explosives, even if the direction
of the wind seemed favourable, for their meeting an approaching airship
fleet, as an upper current might bring them back over the city, where
they might do mischief.

It is, however, quite conceivable that in the future aërial torpedoes
may be devised in the shape of unmanned balloons or aëroplanes
controlled by wireless waves of electricity. Those who saw the
striking experiment of steering a small navigable balloon in a large
hall entirely by wireless electric waves must have realised the
possibilities which may thus be opened out in the future.

       *       *       *       *       *

While writing, the news has come that another Zeppelin has dropped
three bombs on Ostend, the casualty list being one dog. Two unexploded
projectiles were found on a field near Waeragheim. These were probably
thrown from the same airship. They show how constantly missile throwing
from a moving airship may fail to come near the mark. There is no doubt
that to hit particular objects aimed at from airships is by no means
an easy matter. Success would seem to require considerable training in
this particular method of warfare. The late Colonel Moedebeck, in his
well-known pocket-book of aëronautics, makes the following remarks on
the throwing of balloon missiles:--

  We may assume that, if handled skilfully, the object aimed at will
  be hit very exactly. We must distinguish between the throw when the
  airship is at rest and that when it is in motion. In throwing out
  while at rest, which is only possible when the airship can travel
  against the wind, the following points must be considered:--

    (_a_) _The height of the object._--This may be accurately
    determined from the contour lines on the map, or from a
    determination of its normal barometric height. Both must be done
    before starting.

    (_b_) _The height of the airship above the object._--The barometric
    height is read and reduced to normal conditions. The difference in
    heights as found from (b) and (a) gives the height above the object.

    (_c_) _The velocity of the wind._--May be read on an anemometer in
    the airship, or determined beforehand by captive balloons.

    (_d_) _The time of fall._--Given by the law of gravitation from the
    determination under (b).

        The height of fall = h = gt²/2.
        Whence the time of fall t = √(2h/g).

    (_e_) _The resistance of the air._ R = (γ/g)Fv².

    (_f_) _The leeway._--The longer the fall, and the lighter and
    larger the falling body, the stronger is the drift. For known
    missiles, the drift for different heights and wind velocities may
    be determined practically.

    (_g_) _Unsteadiness of the airship._--The irregularity of the
    pressure of the wind, and its constant variation in direction,
    renders it impossible for the airship to remain perfectly steady.

    The elements stated under (_b_) and (_f_) must be rapidly
    determined, and suitable tables have been prepared for this
    purpose. The irregularity of the wind and the peculiarities of the
    airship mentioned under (_g_) render a preliminary trial necessary.
    The drift also is determined by this method, before the large
    air-torpedo is cast out.

    The air-torpedo must be brought by sight vertically over the object
    by steering the airship, the value of the mean drift previously
    determined being allowed for.

    In throwing out a missile while actually travelling, the velocity
    of the airship must be taken into account, as well as the elements
    (_a_) to (_g_) given above, since this velocity is also possessed
    by the body thrown out.

    The determination of the proper point is now greatly increased in
    difficulty. Its position is a function of the relative height of
    the airship above the object, of the velocity, and of the drift,
    and allowance must be made for all these factors. For this purpose,
    motion, either with or against the wind, is the simplest. On
    account of the point on the earth over which the missile must be
    thrown out not being in general well marked, it is necessary to
    use also angles of sight.

    The problem before the aëronaut is, then, as follows:--For a
    given height, velocity, and drift to find the necessary angle of
    depression at which the missile must be thrown out in order that it
    may fall on to the object.

    The casting out of the missile against the object while travelling
    is governed, therefore, by the same rules as those governing the
    discharge of a torpedo from a torpedo-boat.




CHAPTER V

ADVANTAGES AND DISADVANTAGES OF AIRSHIPS


The chief advantages of aircraft that are lighter than air over those
that are heavier than air in warfare are:--

    1. Their speed can be variable.

    2. They can hover over a particular point.

    3. They can be noiseless by cutting off motive power and drifting
    for a while with the wind.

    4. They can from their possible size have long range of action.

    5. They can carry considerable weights.

    6. They are endowed with sustaining power and stability.


1. _Their speed can be variable._

This advantage becomes apparent in cases where they are used both for
scouting and offensive purposes.

In a later chapter it will be pointed out that though the aëroplane
scout has often to make dashes over the enemy, and it would be thought
that from his swift movements his impressions might be vague, still,
in practice, most satisfactory work has been undoubtedly accomplished.
Many, however, will maintain that there are circumstances when it may
be advisable for observers to proceed at variable speeds. When at a
safe height it may be an advantage for the observers to take their time
and leisurely survey the country, observe, and take photographs. The
airship can stealthily travel over camp and fortress and steal secret
after secret of the enemy.


2. _They can hover over a particular point._

The fact that the maintenance of the airship in the air does not
depend upon a certain speed being maintained, as is the case with the
heavier-than-air machine, endows it with the property of being able
to hover in fairly calm weather. The hovering power is certainly an
advantage for such offensive operations as dropping bombs.


3. _They can be noiseless._

At night it may often be possible to approach over a fortress, camp or
city quite noiselessly at a low altitude by shutting off the motive
power and navigating by means of the natural forces alone.


4. _They can from their possible size have long range of action._

From their size and the amount of fuel they can carry it is possible
for them to travel for long distances.

This quality renders them specially fitted for naval purposes,
though possibly in the not very distant future more highly developed
hydroplanes will run them very close.


5. _They can carry considerable weights._

The weights large airships can carry is an advantage in offensive
operations. It enables larger stores of bombs to be carried than is at
present possible with aëroplanes. Then several persons can be carried
long distances in the larger airships.


6. _They are endowed with sustaining power and stability._

As the envelopes of airships are filled with a gas which lifts and
sustains, the great disadvantage of instability which is the bugbear
of aëroplanists is absent. If engines break down or stop, it does not
necessarily mean that the airship must immediately descend. It can
often remain in the air while the machinery is being repaired.

But in spite of these advantages airships have very numerous
counterbalancing disadvantages, so marked, indeed, that it seems a
question whether, if the world decided to entirely use aëroplanes in
their place, it would be much the loser.

The principal disadvantages would seem to be:

    1. The resistance of the gas-bag.

    2. Danger of fire from close combination of petroleum motor and
    gas-containing envelope.

    3. Danger of fire from self-electrification of surface.

    4. Difficulties in the way of applying the propulsive screws in the
    most effective position.

    5. Difficulties of making gas envelope gas-proof.

    6. Great cost of airships.

    7. The great amount of personnel needed for the manipulation of
    large airships.

    8. Great liability of being destroyed by aëroplanes in war.

    9. Insufficient power of quickly rising.


1. _The resistance of the gas-bag._

From a mechanical point of view it is in opposition to science to
attempt aërial navigation by pushing such a large resisting surface as
the envelope of an airship against the air. In navigating an airship
against the wind, as the latter increases speed is diminished, until
a limit is reached when the motive power will be unavailing. Thus
there are weather limitations to the airship. Not that the aëroplane
is unaffected by the weather. That also has its limits; but recent
practice has shown that the proportion of days when aëroplanes can fly
is considerably larger than those on which airships can venture forth
from their sheds.

This disadvantage of the resistance of surface was very manifest in the
earlier experiments with navigable balloons, when only feeble motive
power was available. For instance, in Count Zeppelin’s experiments
in 1900, his two motors of 16 h.p. could not combat a greater wind
force than about three metres a second. Then airships could indeed
only be called toys. It has only been possible to make them partially
successful concerns by enormously increasing motive power. At the h.p.
figures with which the latest made large airships have been endowed,
the wind limit is much lower than in the case of the heavier-than-air
constructions. Though now airships can encounter moderate winds, they
are still fair-weather instruments. For the great records of distance
established by Count Zeppelin favourable meteorological conditions have
been wisely selected. It was M. Santos Dumont who first led the way
in making airships something beyond toys. He, in his picturesque and
world-alluring experiments, first dared to encounter winds which in
force exceeded what would be called calm weather. It is exceedingly
difficult to ascertain what are the exact wind forces overcome by a
body moving in air. The measurements have to be taken from a point
independent of the moving body. We generally find this one important
figure omitted in accounts of airship voyages. M. Santos Dumont’s
experiments gave especially favourable opportunity for ascertaining
correct records of the wind forces overcome. Since M. Santos Dumont
so frequently rounded the Eiffel Tower close to the storey where the
meteorological instruments were placed, the writer obtained from the
authorities of the Eiffel Tower a record of the wind forces registered
on all the days of his experiments. A comparison of those records with
those of M. Santos Dumont’s journeys made it possible to approximately
ascertain the highest wind forces he combated on his journeys round
the tower; these were about five metres a second. M. Santos Dumont,
however, appears to have claimed six metres a second for his highest
wind record.

The brothers Lebaudy in their earlier experiments about doubled the
record of Santos Dumont in this respect. As time has gone on greater
advance has been made, though the limit is still represented by
moderate wind.

There is, perhaps, some consolation in this thought for those who fear
raids of an inimical airship fleet. The proverbial windy nature of our
favoured islands is perhaps even more protection than darkened cities
and artillery shot, though it is well indeed not to neglect the two
latter precautions.

Meteorologically speaking, to make a raid with bulky airships from a
distance over these islands would be a very risky undertaking, fraught
with the greatest danger to the occupants of the airships. It must
be remembered that, chiefly owing to the weather, the history of the
Zeppelin may well be called the history of disaster. For the very
reason of its fragility over and over again it has been the victim of
tempest and flame.

The use of aluminium for the framework of the Zeppelins has been
largely responsible for Count Zeppelin’s repeated weather misfortunes.
There has been a fascination about this brittle metal aluminium for
aëronautical work on account of its lightness. Its employment for
aircraft construction, except for trivial purposes, is, however, a
fallacy. That most practical aëronautical engineer, M. Julliot, in
working out his semi-rigid constructions, has never fallen into the
snare of aluminium allurement, wisely using steel instead. Considering
the aluminium framework of the first Zeppelin constructed was fairly
wrecked by the trifling accident of its falling down from the ceiling
of the shed to the floor, it is a wonder that this species of metal
has been retained, to be crumpled up almost like paper in the many
accidents that have occurred.


2. _Danger of fire from close combination of petroleum motor and
gas-containing envelope._

In airships of all three types--rigid, semi-rigid, and non-rigid--this
danger is constantly present. There have been examples of airship
conflagrations in mid-air, but the greatest danger of conflagrations
is in descending when the airships have been overtaken by strong and
gusty winds. As has before been stated, fire has been the great
destroyer of the Zeppelins.

The nearer the car containing the motors is placed to the gas envelope,
the greater the fire risk becomes. The Parsifal airship, in which the
car is suspended a considerable distance from the gas-bag, should in
this respect be the safest of all the types of airships yet constructed.


3. _Danger of fire from self-electrification of surface._

This appears to be a great danger in the case of airships whose
gas-bags are made with india-rubber surfaces. No less than two
Zeppelins have been destroyed from this cause. In the case of the
explosion of the gas in a Zeppelin of 1908, when it burst from its
anchorage at Echterdingen, the destruction of the airship appears
to have been caused by electric sparks produced by the friction of
the material of which the gas-bag compartments were made. Colonel
Moedebeck, in the _Aëronautical Journal_ of October, 1908, gave an
expert opinion as to the cause of this accident:--

    The balloon material, which is india-rubber coated, has the
    peculiar property of becoming electrified in dry air. When rolled
    up or creased in any way it rustles, and gives out electric
    sparks, the latter being (as shown by the experiments undertaken
    by Professor Bonsteim and Captain Dele for the Berlin Aëronautical
    Society) clearly visible in the dark.

    Now, the lower parts of the material of which the gas-cells are
    composed would, owing to the height to which the airship had
    ascended (1,100 m.) and the release of gas from the valves, become
    creased or folded upon each other, and the rubbing thus produced
    would be quite sufficient to generate the electric sparks above
    referred to. Under ordinary circumstances, when the space between
    the gas-cells and the outer envelope of the airship is full of
    atmospheric air, continually renewed, as when it is in full flight,
    these sparks would be harmless enough, but when the ship is at
    anchor, as at Echterdingen, this is not necessarily the case.

    We know that the carefully made tissue of the Continental
    Caoutchouc Company resists the penetration of hydrogen very
    strongly, but some may have leaked through into the space between
    the cells and the outer envelope, while it seems very probable that
    when the mechanics opened the valves, and the long axis of the
    balloon became inclined, more hydrogen entered this space and an
    explosive mixture was formed.

    According to the description given by eye-witnesses, the explosion
    took place after the forepart of the vessel (dragging its
    anchor) struck the ground. The shock thus caused would have been
    transmitted to the creased and wrinkled gas-cells, and the tearing
    of the material, already in an electrified condition, might easily
    have generated sufficient sparks to detonate the explosive mixture.

Again, in 1912, there was a repetition of this kind of disaster in the
case of the destruction of another Zeppelin, the “Schwaben.” In this
case the framework of the airship had got broken, being battered about
in landing in an adverse wind. The india-rubber-coated bags were rubbed
against each other, with the production of electric sparks. These
either set fire to the gas issuing from one of the gas-bags or exploded
the mixture of air and gas contained in the space between the gas-bags
and outer covering of the airship. Perhaps it was on account of this
accident that gold-beaters’ skin has sometimes been used for the gas
containers of the Zeppelin airships.


4. _Difficulties in the way of applying the propulsive screws in the
most effective position._

Most airships are exceedingly defective in this respect, the screws
being applied to the propulsion of the car and not to the whole system.
The result is that the cumbersome gas-bag lags behind. Certainly, one
of the best points in a Zeppelin was the attachment of the screws to
the airship framework above the cars, thus securing more advantageous
position. This, however, only amounted to something like half measures.
In the case of the ill-fated airship “La Paix,” the Brazilian aëronaut
Severo undoubtedly aimed at the ideal, though the experiment cost
him his life. He devised the ingenious system of combining balloon
and car in one symmetrical melon-shaped body, through the centre of
which passed longitudinally the shaft which revolved the propelling
screws at either end. The screws were therefore in the position in
which to propel the whole system and not the car only. This, however,
necessitated the introduction of a very small space between the car
and balloon proper. By reason of this very small space the presence of
the petroleum motor in the car could not fail to be dangerous, and was
the cause of the fiery end of Severo’s balloon and the death of the
inventor and engineer. On the morning of the ill-fated May 11th, 1902,
Severo and Sachet ascended in “La Paix.” A few moments after the ascent
the balloon exploded, in the words of an eye-witness, like a crash of
thunder, and the occupants were precipitated to the ground.

In spite of the engineering advantages of Severo’s system no one has
dared to revive the plan.

It has, however, been pointed out by the writer--and the suggestion
elicited the keen interest of the late Professor Langley--that if
electricity could be used as the motive power in an airship the Severo
system could be reasonably revived. Then the electric motors could be
inside the gas-bag. There, electric sparks and electric heating could
do no harm. For it is only the borderland that is the place of danger,
where there are oxygen atoms to combine with the hydrogen atoms.
In the case of a balloon filled with gas it is surprising to what
short distance the danger zone extends. In the case of the writer’s
electric signalling balloons, on one occasion the ladder framework
which supported the incandescent lamps was being hauled up into the
balloon. Through some fault in the connections there was sparking at
the framework just as it had passed over the dangerous borderland. The
sparks went on with safety. An inch or two lower and there would have
been an explosion!

But on account of the weight of the battery the practical application
of electricity for propelling navigable balloons seems to be as far
off as it was in the days of “La France,” and in airships we have to
continue placing the screws in the wrong place.


5. _Difficulties of making gas envelope gas-proof._

The absence of the knowledge how to obtain a really gas-proof
envelope is, no doubt, one of the greatest difficulties of airship
construction. As has already been pointed out, the gas-holding quality
of gold-beaters’ skin is remarkable. Its cost, however, is fairly
prohibitive in the case of large airships. A material which is a
combination of india-rubber and cotton surfaces is now generally used
for large airships, but this has undoubted disadvantages. India-rubber
is a substance which time, low temperature, and certain climatic
conditions deteriorate. All those who have worked with india-rubber
experimental _ballon-sondes_ (sounding balloons) can testify to its
perishing qualities. Very much can be accomplished with a brand-new
airship. Turned out of a factory it will retain its gas-holding
qualities for a short time excellently. The lapse of time reveals
deterioration and leakiness.

Considering the extreme importance of a varnish that will retain
pure hydrogen for a reasonable time, it is a matter of surprise that
chemists should have almost entirely neglected its production. Mr.
W. F. Reid alone of British chemists seems to have given any serious
thought to the question. In a paper which Mr. Reid read before the
Aëronautical Society of Great Britain, he made some exceedingly
important suggestions in the way of obtaining balloon and airship
varnishes. In case this little volume should fall into the hands of
any chemists who may like to devote their powers of original research
to the production of one missing link in airship construction, the
following quotation from Mr. Reid’s remarks are appended below.

    Varnishes may be divided into two classes--those in which the film
    solidifies or “dries” by absorption of oxygen from the air, and
    those in which the varnish “sets” by the evaporation of a volatile
    solvent in which the solid ingredients have been dissolved. To
    the first class belong the drying oils, chiefly linseed oil, for,
    although there are a number of “drying” oils, but two or three
    of them are used commercially in the manufacture of varnishes.
    When exposed to the air, especially in warm weather, linseed oil
    absorbs oxygen and forms an elastic translucent mass termed by
    Mulder “linoxyn.” This linoxyn has completely lost its oily nature,
    does not soil the fingers, and is, next to india-rubber, one of
    the most elastic substances known. It possesses but little tensile
    strength, however, and can be crumbled between the fingers. It
    forms the basis of all linseed oil paint films, and is largely
    used in the manufacture of linoleum. Linoxyn, however, is not, as
    Mulder supposed, the final product of the oxidation of linseed oil.
    When exposed to the air it is still further oxidised, and then
    forms a sticky, viscid mass, of the consistency of treacle and of
    an acid reaction. This latter property is of importance because
    it is due to it that fabrics impregnated with linseed oil so soon
    become rotten. In order to hasten the oxidation of linseed oil it
    is usually heated with a small quantity of a lead or manganese
    compound, and is then ready for use. No method of preparation can
    prevent the super-oxidation of linseed oil, but experience has
    indicated two ways of diminishing the evil effects so far as paints
    and varnishes are concerned. The first is to mix the oil with
    substances of a basic character or with which the acid product of
    oxidation can combine. In the case of paints, white lead or zinc
    oxide are chiefly used for this purpose. The other method consists
    in mixing with the oil a gum resin which renders the film harder
    and prevents liquefaction. Such a mixture of linseed oil and Kauri
    gum forms an elastic, tough mass, which is much more durable than
    the linoxyn alone, and also possesses greater tensile strength.
    During oxidation the linseed oil absorbs about 12 per cent. of
    its weight of oxygen, and when the area exposed is very large in
    proportion to the weight of the oil the temperature may rise until
    the mass catches fire. At a high temperature the super-oxidation
    of the oil takes place more rapidly than in the winter, and I have
    seen fabrics that had only been impregnated with an oil varnish
    for a month cemented together in one sticky mass, and, of course,
    completely ruined. When the linseed oil is thickened by the
    addition of a gum resin, it is too thick for direct application,
    and is thinned down with a solvent, usually turpentine or a mixture
    of this with light petroleum. Many resins and gum resins are used
    in the manufacture of varnishes in conjunction with linseed oil,
    but none of them can deprive the oil of the defect referred to,
    and if used in too large a proportion they become too brittle for
    balloon purposes. Both scientific investigation and practical
    experience show that any varnish containing linseed oil must be
    looked upon with suspicion by the aëronaut, in spite of the glowing
    testimonials some manufacturers are always ready to give their own
    goods.

    When we consider those varnishes which are solutions and which do
    not depend upon oxidation for their drying properties we enter upon
    a very wide field.

    Practically any substance that is soluble in a neutral solvent and
    leaves an impermeable film on drying is included in this class. One
    of the simplest examples is gelatine in its various forms, with
    water as a solvent. Until recently glue or gelatine would have
    been useless for our purpose on account of its ready solubility
    in water, but now that we are able to render it insoluble by
    means of chromic acid or formaldehyde it comes within the limits
    of practical applicability. A fabric may be rendered almost
    impermeable to gas when coated on the inside with insoluble
    gelatine, and on the outside with a waterproof varnish. Animal
    membranes are far less permeable to gases than fabrics coated with
    varnishes of the usual kinds. A balloon of gold-beaters’ skin, if
    carefully constructed, will retain hydrogen gas for a long time,
    and if treated with gelatine that is afterwards rendered insoluble
    it becomes practically impermeable. Fabrics treated with linseed
    oil varnish, on the other hand, allow gas to pass with comparative
    ease. This is not a question of porosity or “pinholes,” as is
    sometimes imagined, but a property inherent to the material.
    Hydrogen or coal gas is absorbed on the one side of the film and
    given off on the other in the same way as carbonic oxide will
    pass through cast iron. An inert gas, such as nitrogen, does not
    appear to diffuse in this way, even when there is a considerable
    difference in pressure between the two sides of the film. Such a
    varnished fabric transmits hydrogen readily, but retains nitrogen,
    and is perfectly watertight. In filling up the interstices of a
    fabric composed of cellulose the most obvious substance to use
    would be cellulose itself, but until recently solutions of this
    kind were difficult to obtain. Toy balloons have long been made
    of collodion, and are fairly satisfactory, but a cotton fabric
    impregnated with pure collodion becomes hard and even brittle.
    Celluloid solution, which is collodion with camphor and a small
    quantity of castor oil, is more flexible, but, probably on account
    of the camphor, is more permeable to hydrogen than collodion. A
    variety of collodion known as flexile collodion is a solution of
    collodion cotton with a slight addition of castor oil, and is
    much to be preferred to any of the preceding forms. In using it
    great care must be taken to exclude moisture, as the presence of
    this renders the film opaque, in which case it is always more or
    less porous. A substance allied to collodion is velvril material,
    composed of collodion cotton and nitrated castor oil. It is tough
    and flexible, even in thick films, and gives a good coating to
    paper or cotton fabric. Unless very carefully prepared, however,
    acid products may be generated from the decomposition of the
    nitro-compounds present, in which case the strength of the fabric
    would suffer. Another form of cellulose in solution is viscous,
    which forms a good coating when applied in a very thin layer, but
    makes the fabric harsh and brittle if used in excess. The solutions
    of this substance do not keep well and are liable to spontaneous
    decomposition.

    The difference in flexibility between thin and thick films of the
    same materials is very considerable.

    Given an elastic, supple cement, such as is afforded by
    concentrated solutions of some of the above-mentioned substances,
    it is quite possible to cement a tough, close-grained paper to
    a cotton fabric of open mesh, and the compound material thus
    produced is much more easily rendered impermeable than the fine
    cotton fabric now used. An extremely tough paper made from silk,
    a recent invention of T. Oishi, a Japanese manufacturer, would be
    specially useful for such a purpose....

    It will be noticed that the texture is very compact and free from
    pores, as might, indeed, be expected on account of the fineness of
    the silk fibres of which it is composed. It must not be forgotten
    that cotton fibres are tubes, and gas may pass through them even
    when they are embedded in an impermeable film. Silk fibres, on the
    other hand, are solid, as well as stronger than cotton.

    Another way in which a tough, flexible cement may be utilised is
    to cement a metal foil to a textile fabric. Aluminium foil, for
    instance, cemented to cotton by means of flexile collodion, gives a
    completely impermeable fabric of much greater suppleness than the
    sheet aluminium hitherto used for balloons.

    Fine aluminium flakes dusted upon the freshly varnished surface
    adds greatly to the impermeability of the fabric, and the same may
    be said of coarsely powdered mica.

It may be noted in this connection that an impermeable varnish does not
only apply to balloon and airship construction, but will also have its
use for impregnating the planes of the heavier-than-air machines.


6. _Great cost of airships._

The cost of airships compared with that of aëroplanes certainly favours
the extended use of the latter in war. It is easy to spend £50,000 on
a very large airship. Supposing the cost of an aëroplane seating two
persons is £1,000, it is a question from an economic point of view
whether the possession of fifty aëroplanes is not far better military
value for the money expended on the solitary airship. But in the case
of the latter it is not only initial expense that has to be considered,
but cost of housing, maintenance, and hydrogen gas. These items are
very considerable. The upkeep of one large airship very much exceeds
that incurred with fifty aëroplanes.


7. _The great amount of personnel needed for the manipulation of large
airships._

It is no exaggeration to say that the ground manipulation of large
airships necessitates the attendance of quite an army. In the case of
a Zeppelin the exigencies of wind may call for the assistance of 300
trained sappers on landing. This is the reason why it is so advisable
to have the resting-places of large airships on water. In the case of
rigid airships a slight bump on the earth may do considerable damage.
Colonel Moedebeck has laid especial stress on the advisability of water
landing.

    In practice it is never possible, even by working the motor
    against the wind, to avoid a certain amount of bumping, since the
    aërostatical equilibrium is not easily judged and allowed for,
    especially in strong winds. On this account the safer water landing
    is always preferable.

    An airship can be anchored more easily with the point against
    the wind on water. It is quite impossible to anchor on land
    when assistance is not forthcoming to hold down the airship. On
    water, also, the airship will give a little to side winds and to
    alterations in the direction of the wind, without overturning. On
    land this danger is not excluded, even with rigid airships. Of
    course, a watertight and seaworthy car is a necessary condition for
    landing on water.

    The landing requires great attention, and rapid, decisive handling
    and management on the part of the aëronaut.

In the opinion of the same expert airship travelling on a large scale
would not be possible without the publication of special charts,
which would furnish information concerning natural airship harbours,
and their relation to various winds, and also of the various airship
sheds which may be erected. He states it would be highly dangerous to
undertake airship voyages without the existence of suitable stations
against storms, and where gas supplies, driving material, and ballast
could be renewed.


8. _Great liability of being destroyed by aëroplanes in war._

This is no doubt one of the greatest dangers the airship has to face
in war. The aëroplane is the airship’s deadliest enemy. So terrible to
the airship is this hornet of the air that the former has no chance
of making an attack. It must ever remain on the defensive. The speed
and quickly rising power of modern aëroplanes settles this question.
When the aëroplane is advancing the airship cannot escape. Nor can it
now any longer rise to safe altitude, for the nimbler heavier-than-air
machines can easily outdo it.

The only salvation of the attacked airship is its mitrailleuse gun
fixed on the platform at its topmost part, but the chance of hitting
the swiftly advancing aëroplane is fairly remote.

There are more ways than one in which the fatal attack of aëroplane
v. airship can be made. The airman can, indeed, ram the gas-bags by
hurling himself and machine against it. Then destruction would be swift
and sure, with the probable loss of the airman’s own life. Better
tactics would be to fly above, and drop suitable weapons on the fragile
gas-bag; a few sharp and jagged stones would probably suffice. Sharp
darts of steel would be all-effective. So easy, indeed, would it be for
one aëroplane skilfully handled to end the existence of the largest
airship that one cannot refrain from asking the question whether on
this account alone it can survive as the instrument of war?


9. _Insufficient power of quickly rising._

This is a point which wants the attention of the aëronautical engineer.
The old-fashioned spherical balloons were made to rise and fall by the
alternate sacrifice of gas and ballast. Thus the very life-blood of the
balloon became quickly exhausted. It was obvious that when airships
supplanted balloons the former must be supplied with a less exhausting
process of vertical movement.

As has already been mentioned, when treating of the Zeppelin airship,
for the purpose of rising horizontal planes are now fitted to
airships. Some engineers have thought these should be supplemented by
a mechanical device, so that the speed of rising might be augmented.
The late Baron de Bradsky provided his airship with a horizontal
screw placed beneath the car. But one horizontal screw beneath an
airship tends to twist it round--to convert it into an aërial top.
To avoid this effect it would be necessary to have two horizontal
screws rotating in opposite directions. This precaution was absent
in de Bradsky’s construction, and it kept on twisting round, with
the disastrous effect that the steel wires which held the car to the
balloon snapped, with tragic results. But the idea of the horizontal
screw is worth reviving. It has been a cherished plan of M. Julliot to
include the principle in his designs, but on account of extra weight he
has, I believe, hitherto not tried the interesting experiment.

The colour of most of the airships is a disadvantage, though this is a
matter so easy of alteration that it has not been included in the list
of disadvantages.

In military airships, and, it may be added, aëroplanes also, the colour
should be a neutral tint that is as invisible as possible against the
sky. Most of the airships have been made a glaring yellow, so that the
india-rubber in the envelopes may be better preserved from the action
of light. This protection may have to be sacrificed to the overpowering
advantages of invisibility in the case of naval and military airships.




CHAPTER VI

THE ADVENT OF THE AËROPLANE


The year of 1908 will be memorable in aëronautical science for its
demonstration of the possibility of mechanical flight. Day after day
in France and America was then seen the spectacle of men flying in the
air, with a grace equal to that of the soaring bird. This was done with
a machine not raised by the buoyancy of a gas, but with one that was
heavier than the medium in which it travels, and whose sustentation
and direction was accomplished by dexterity and skill. The experiments
of the brothers Wright were new triumphs of man, new examples of the
old truths that a difficulty is a thing to be overcome, and that the
impossibility of to-day may be the achievement of to-morrow. This
progress in human flight was not the result of any new discovery; it
was the sequence of a long series of experiments; nor was it one
nation only that forged the links that connected past researches to the
successful issues of the present century.

It is, however, not without honour to the British nation that one of
the fundamental principles of the biplane was proposed and elucidated
by a Briton in 1866. I refer to the important principle of superposed
surfaces advanced in that year by the late F. H. Wenham. He pointed
out that the lifting power of such a surface can be most economically
obtained by placing a number of small surfaces above each other. Wenham
built flying machines on this principle with appliances for the use of
his own muscular power. He obtained valuable results as to the driving
power of his superposed surfaces, but he did not accomplish flight.

In 1872, H. von Helmholtz emphasised the improbability that man would
ever be able to drive a flying machine by his own muscular exertion.
After his statements there came a period of stagnation in the attempts
to navigate the air by bodies heavier than air.

It is difficult to say how much aëronautical science owes to two
illustrious names--Sir Hiram Maxim and the late Professor Langley.
The two eminent men took up the subject of flight about the same
time in the last decade of the last century, and applied to it all
the scientific knowledge of the time. The flying machine had come to
be associated in the public mind with foolhardiness and failure. In
the discussion following Sir Hiram Maxim’s paper, “Experiments in
Aëronautics,” read before the Society of Arts on November 28th, 1894,
he said, “At the time I took up this subject it was almost considered
a disgrace for anyone to think of it; it was quite out of the question
practically.” But these two scientific men stepped into the breach,
rescued aëronautics from a fallen position, and fired in its cause the
enthusiasm of men of light and leading.

Sir Hiram Maxim built the largest flying machine that had been
constructed. It spread 4,000 square feet of supporting surface, and
weighed 8,000 lb. The screw propellers were no less than 17 feet 11
inches in diameter, the width of the blade at the tip being 5 feet.
The boiler was of 363 h.p. The machine ran on wheels on a railway
line, and was restrained from premature flight by two wooden rails
placed on each side above the wheels. On one occasion, however, the
machine burst through the wooden rails and flew for 300 feet.

In 1896 Langley’s tandem-surfaced model aërodrome had luck with the
aërial currents, and flew for more than three-quarters of a mile over
the Potomac River. This machine had 70 square feet supporting surface,
weighed 72 lb., and had an engine of 1 h.p., weighing 7 lb. It is well
known how, in later years, Langley exaggerated his model into a machine
which carried a man, and how twice, when it was put to the test over
water, at the very moment of being launched, it caught in the launching
ways and was pulled into the water. It is interesting to note that
the American aviator, Mr. Curtiss, has lately unearthed the Langley
flying machine, and flown on it. Thus to Langley has come a posthumous
aëronautical honour.

Lilienthal, in Germany, in considering equilibrium, experimented with
what are called gliding machines--aëroplanes which are launched from
some hillside against the wind, and depend upon gravity for their
motive power. In this way the art of balancing could be practised on
motorless gliders. With Lilienthal commenced the age of systematic
experimental flight; he made the discovery of the driving forward
of arched surfaces against the wind; he made some 2,000 glides,
and sometimes from a height of 30 metres he glided 300 metres. The
underlying principle of maintaining equilibrium in the air has been
recognised to be that the centre of pressure should at all times be on
the same vertical line as the centre of gravity due to the weight of
the apparatus. Lilienthal sought to keep his balance by altering the
position of his centre of gravity by movements of his body. One day he
was upset by a side gust and was killed. Pilcher, in England, took up
his work. With his soaring machines he made some hundred glides, but he
also made one too many. One day, in 1899, in attempting to soar from
level ground by being towed by horses, his machine broke, and he fell
to the ground. He died shortly afterwards, a British martyr of the air.

Mr. Octave Chanute’s experiments in 1896–1902 formed important links
in flight development. He first introduced the vital principle of
making the surfaces movable instead of the aviator, and he made use of
superposed surfaces. Though his work was a stage in the development of
the flying machine, it was reserved to two other geniuses, the brothers
Wright, to bring flight to a point of progress where prejudiced critics
would be for ever silenced.

The brothers Wright first carried out laboratory experiments; they
then, in 1900, first began to experiment with gliding machines at Kitty
Hawk, North Carolina. With the comparatively small surfaces (15.3
square metres) they used in that year, they endeavoured to raise the
machine by the wind like a kite; but finding that it often blew too
strongly for such a system to be practical, in 1901 they abandoned the
idea and resorted to gliding flight.

These machines of 1901 had two superposed surfaces, 1.73 metres apart,
each being 6.7 metres from tip to tip, 2.13 metres wide, and arched
1-19th. The total supporting surface was 27 square metres. They
dispensed with the tail which previous experimenters had considered
necessary. Instead, they introduced into their machine two vital
principles, upon which not only the success of their preliminary
gliding experiments depended, but also their later ones with their
motor-driven aëroplanes--(1) the hinged horizontal rudder in front for
controlling the vertical movements of the machine; (2) the warping or
flexing of one wing or the other for steering to right or left.

Later, a vertical rudder was also added for horizontal steering.
The combined movements of these devices maintained equilibrium. The
importance of the system of torsion of the main carrying surfaces
cannot be overestimated. We have only to look to nature for its _raison
d’être_, and observe a flight of seagulls over the sea: how varied are
the flexings of nature’s aëroplanes in their wondrous manœuvrings to
maintain and recover equilibrium! Since the appearance of the Wright
motor-driven aëroplane, the principle of moving either the main
surface or attachments to the main surface has been very generally
adopted in other types of flying machines. A feature of these early
experiments was the placing of the operator prone upon the gliding
machine, instead of in an upright position, to secure greater safety
in alighting, and to diminish the resistance. This, however, was
only a temporary expedient while the Wrights were feeling their way.
In the motor-driven aëroplanes the navigator and his companion were
comfortably seated. After the experiments of 1901, the Wrights carried
on laboratory researches to determine the amount and direction of the
pressures produced by the wind upon planes and arched surfaces exposed
at various angles of incidence. They discovered that the tables of the
air pressures which had been in use were incorrect. Upon the results
of these experiments they produced, in 1902, a new and larger machine.
This had 28.44 square metres of sustaining surfaces--about twice the
area that previous experimenters had dared to handle. The machine was
first flown as a kite, so that it might be ascertained whether it
would soar in a wind having an upward trend of a trifle over seven
degrees; and this trend was found on the slope of a hill over which
the current was flowing. Experiment showed that the machine soared
under these circumstances whenever the wind was of sufficient force to
keep the angle of incidence between four and eight degrees. Hundreds
of successful glides were made along the full length of this slope,
the longest being 22½ feet, and the time 26 seconds. A motor and screw
propellers were then applied in place of gravity, in 1903, and four
flights made, the first lasting 12 seconds, and the last 59 seconds,
when 260 metres were covered at a height of two metres.

In 1904, several hundred flights were made, some being circular.
All this work was carried on in a secluded spot and unpublished. In
December, 1905, the world was startled by the news that the brothers
Wright had flown for 24¼ miles in half an hour, at a speed of 38
miles an hour. More than this at the time the brothers would not say,
and for three years the world thirsted for the fuller knowledge only
revealed in 1908. In the interval some went so far as to distrust the
statements of the brothers Wright; but those who, like myself, had had
the privilege of correspondence with them from their first experiments
felt the fullest confidence that every statement they had made was fact.

I have somewhat dwelt on the preliminary experiments of the brothers
Wright with their gliding structures as indicating the rapidity of
progress attained when sound scientific method is combined with
practical experiment. Too often in the past there has been a tendency
amongst the workers in science to keep theory and practice apart. They
are, however, interdependent. Each has a corrective influence on the
other.

To the labours of the Wright brothers we certainly owe the advent of
the mobile and truly efficient military air scout. It is their efforts
that have revolutionised warfare. In the present war we see only the
beginnings of what will one day be; but they are none the less truly
prophetic.

It was the enthusiastic Captain Ferber, who later became a victim
to his ardour for aërial achievement, who realised what the brothers
Wright had accomplished for military aëronautics. The latter having
entered into communications with the French Government respecting
the sale of their machines, Captain Ferber was deputed by the French
Government to go to America and report on their claims. As the brothers
Wright at that time so carefully guarded the secrecy of their details,
he was not allowed to see the machine when he arrived, and had to be
content with the mere hearsay of certain persons at Ohio, who had
witnessed their flights. But he had sufficient faith in the brothers
Wright to recommend the French Government to buy their invention.

The negotiations, however, fell through at the time, but in 1908 Wilbur
Wright came to France to carry on experiments at Le Mans, while his
brother, Mr. Orville Wright, went to Fort Myers in America.

In Wilbur Wright’s machine at Le Mans, the two superposed slightly
concave surfaces were about 12.50 metres long and 2 metres wide.
They were separated by a distance of 1.80 metres. At a distance of 3
metres from the main supporting surfaces was the horizontal rudder
for controlling the vertical motions; this was composed of two oval
superposed planes. At 2.50 metres in front of the main supporting
surfaces was the vertical rudder, composed of two vertical planes.

The 25 h.p. motor was placed on the lower aëro-surface; this weighed
ninety kilogrammes. At the left of the motor were the two seats, side
by side, for the aëronaut and his companion. The two wooden propellers
at the back of the machine were 2.50 metres in diameter. They revolved
at the rate of 450 revolutions per minute.

The area of the sustaining surfaces was fifty square metres. The weight
of the whole machine (with aviator) was about 450 kilogrammes. Levers
under the control of the aviator regulated the various functions of the
machine, the flexing of the carrying surfaces, the movements of the
horizontal rudders, the vertical rudder, etc.

Soon after the experiments at Le Mans had commenced there came the
news of the accident to Mr. Orville Wright’s machine in America, in
which the latter’s leg was broken and Lieutenant Selfridge was killed.
This was a critical moment for aëronautical science. I can myself
bear witness to its depressing effect on an illustrious aëronautical
assemblage, for I was myself present at Wilbur Wright’s aëroplane shed
when the telegram came bearing the sad news. The sacrifice of one life
at that moment seemed to counterbalance the advantages gained by the
triumph of the brothers Wright. Even Wilbur Wright himself seemed to
half repent he had conquered the air! He exclaimed, “It seems all my
fault.” It was, indeed, then little thought what the future toll of the
air would have to be.

Fortunately for aëronautical progress, two days afterwards Wilbur
Wright recovered his nerve, and made the convincing flight of 1 hour 31
minutes 25 4-5th seconds.

From that day onwards there has been an increasing flow of progress in
the mastery of the air.




CHAPTER VII

TYPES OF AËROPLANES


France has indeed been the breeding-place for types of aëroplanes.
From France have the nations of late been largely gathering them--save
Germany. She has preferred to evolve her own distinctive types.
Even before Wilbur Wright appeared with his machine at Le Mans and
the details were known, hearsay of his doings had fired the French
imagination to do what he had done. In ignorance of the vital principle
of movable surfaces that the Wrights had evolved, there came into
existence the unbending, rigid type that was not destined to survive.

The first of these was the bird of prey of M. Santos Dumont. Rudely
simple was it in its construction. Two box kites formed the supporting
surface. In the centre was the motor, with the screw behind. To attain
flight the machine was run upon wheels along the ground until a certain
speed was reached, when the machine rose into the air. With this the
inventor did not do much more than make aërial jumps; but rude as it
was it contained one feature which has since been retained in all
aëroplanes. In this one respect it was an advance--and a very necessary
one--upon the Wright machine. That feature was the attachment of
wheels to the machine that has been mentioned above. This was, indeed,
an important step in the evolution of the aërial scout. Had it been
necessary to continue using the external starting catapults that were a
feature of the early experiments of the Wrights, the application of the
aëroplane to warfare would have been somewhat limited.

The well-known Voisin machine was another outcome of this period, but,
imperfect as it was, it brought Mr. Henry Farman into fame, for on it
he was the first man in Europe to fly any distance worthy of mention.


THE FARMAN BIPLANE.

Discontented with the Voisin machine, Mr. Henry Farman constructed one
of his own design. Though it appeared at an early stage of aëroplane
development, it still remains one of the most efficient types of
biplanes. It has been used enormously in France, and armoured Farmans
play an important part in the great war that is proceeding.

Mr. Farman quickly realised that for maintaining lateral stability the
vertical planes fitted between the main planes of the Voisin type were
a very poor substitute for the wing-warping method of the brothers
Wright. He, however, produced the movement of the main surfaces in
an original manner. He hinged small flaps to the rear extremities of
the main planes. These he called “ailerons.” They produce much the
same effect as the wing-warping method of the brothers Wright. When
the biplane tilted sideways, the flaps were drawn down on the side
that was depressed. The pressure of the air on the flaps forced the
aëroplane back on an even keel. In the normal condition the flaps
flew out straight in the wind on a level with the main planes. Another
noticeable feature of Mr. Farman’s machine was the production of the
first light and efficient landing chassis. This was a combination of
wooden skids and bicycle wheels. Below the biplane, on wooden uprights,
he fitted two long wooden skids. On either side of each skid he placed
two little pneumatic tyred bicycle wheels, connected by a short axle.
These were held in position on the skid by stout rubber bands passing
over the axle.

In a general way the wheels raised the skids from the ground, but if
the ascent was abrupt the wheels were forced against the rubber bands
and the skids came in contact with the ground. With the abatement of
the force of the shock the wheels came again into play.

Simplification of the chassis is becoming evident in the latest forms
of all military aëroplanes, the reduction of weight in this portion of
the apparatus being important.

To Mr. Farman belongs the credit of having first applied to his
aëroplane the now famous Gnome motor, in which seven or more cylinders
revolve. It can truly be said that the influence of this motor on
facilitating flight generally, and very particularly military aviation,
has been nothing short of prodigious. The aëroplane, like the airship,
had to wait for the light petroleum motor. Its advent made flight
possible, but achievement in flight would have been comparatively small
had it not been for the welcome appearance of a motor specially adapted
to the purpose.

The early forms of aëroplane engines in which the cylinders were fixed
had proved to be quite unreliable owing to the high speeds at which
the engines had to work. Overheating, loss of power, and stopping
were frequent occurrences. The water-cooling and air-cooling systems
introduced were equally inefficient. The very fact that the cylinders
of the Gnome motor revolved effected the desideratum of automatic
cooling, and also gave a smooth, even thrust to the propeller.

If the aëroplanes in the present war were flying over the enemy’s lines
with old-fashioned engines, they would be dropping down into hostile
hands as quickly as dying flies from the ceiling on the first winter
days.

After the introduction of the Gnome motor, it was quickly realised that
the speeds secured by its use gave the aëroplane a stability that was
absent in the more slowly moving machines. Winds that were the bugbear
of the aëroplanists could then be combated, and the aëroplane ceased
to be the fine-weather machine. Heights could then be climbed that a
little while before were undreamt of. It is said that there are some
disadvantages in the case of revolving cylinders--that they have been
known to produce a gyroscopic effect that has upset the machine. This,
however, is a somewhat doubtful point. It may be urged that the greater
silence of motors with fixed cylinders is an advantage in war. This may
sometimes be so, and it is quite possible that for offensive aëroplanes
a special type of motor may be in the future evolved.

To return to the other features of the Farman machine. The plan he
adopted in his racing machines of making the upper plane larger than
the lower one was a valuable step in speed-producing machines.

The records won by Mr. Farman with his machines alone testify to
its efficiency. Often he has held the world’s records of distance,
duration, and height, wrestling, indeed, for these with the Blériot
monoplane.

In 1911 Mr. Farman began to make types of biplanes specially designed
for military use, and in which he studied how he could best give the
observing officer an unobstructed view of the ground beneath him. He
placed both pilot and observer in seats projecting in front of the main
planes. He also made a new departure in placing his upper plane in
advance of the lower one. He claimed that this facilitates climbing and
descent. He has, however, quite lately evolved a newer type of scouting
machine.

In this the lower plane is only one-third the span of the upper one.
The nacelle is not mounted on the lower plane, as in the ordinary
types of his machine, but, instead, strung from the main spars of the
top one. The usual chassis is absent. There is a single running wheel
mounted at each end of the lower plane, which is brought very close to
the ground. The upper and lower planes are separated by four pairs of
struts. The tail is similar to that used on the ordinary type.

The following are the dimensions of one of the latest 1914 types of
one-seated Farman machines:--

  Length             3.75 metres
  Span               11.50 metres
  Area               26 sq. metres
  Weight (total)     290 kgs.
    „    (useful)    175 kgs.
  Motor              80 h.p. Gnome
  Speed              110 km. per hour

The following are the details of one of his high-power hydroplanes
(1914):--

  Length              8.80 metres
  Span                18.08 metres
  Area                50 sq. metres
  Weight (total)      605 kgs.
    „    (useful)     275 kgs.
  Maximum speed       105 km. per hour

[Illustration:

                                                     [_Topical Press._
  A BLÉRIOT MONOPLANE IN FLIGHT,

showing one of the two wings attached to the tubular body of machine,
chassis, stabilising plane, and rudder at rear.]


THE BLÉRIOT MONOPLANE.

At the same time that Mr. Henry Farman was making his first flights on
his biplanes, M. Blériot was experimenting with monoplanes. His first
attempts were disastrous. Time after time he was dashed to the ground.
But he persevered, and produced a machine which by its performance
staggered the aëronautical world.

When he was first experimenting most people thought that it was
in superposed surfaces that success alone lay. They forgot the
researches of Langley. These had showed that support depended on
two factors--speed and surface; that when speed is increased a less
supporting surface will suffice. The success of Blériot took the world
by surprise. If I were asked to name the men who have done most to
further practical aëronautical development, I should unhesitatingly
say: 1, the brothers Wright; 2, Blériot; 3, Pégoud.

The first have been already dealt with. I will speak of the two latter
together.

Of the work of both there has been one underlying
characteristic--simplicity. The former has produced a machine stripped
indeed of encumbering complexities, in which the restriction of
accessories to what is absolutely necessary is carried to a fine art;
the latter with that very machine has performed experiments in the air
that the most sanguine enthusiast of a few years back would have deemed
far beyond the region of the possible. In his graceful air diving,
looping the loop, and flying upside down, he gave the world a great
object-lesson of the materiality of air. He showed the air can give the
aviator as much support as the water can to a fancy swimmer. He showed
that if the aëroplane is an unstable thing, the human brain can supply
the stability; that in human flight, like the bird and its wings, the
machine and individual can be in closest touch. No one has stripped
the air of its terrors as has M. Pégoud. In the yielding air there is
indeed safety! It is the ground the aviator has to fear!

I have spoken of the simplicity of the Blériot monoplane. In the
machine with which M. Blériot flew over the Channel in 1909, stretched
like the wings of a bird on either side of a tubular wooden frame
partly covered with canvas and tapering to the rear, are placed the two
supporting planes, rounded at the ends. At the front end is placed the
motor (in the original type a three-cylindered engine, now replaced by
the Gnome motor), geared direct to a 6 feet 6 inches wooden propeller,
and on a level with the rear end of the planes. Immediately behind
the engine is the petrol tank, and behind that the aviator’s seat.
Near the rear end of the frame and underneath it is the fixed tail,
with two movable elevating tips. How simple is the working of this
monoplane! Moving a lever backwards and forwards actuates the tips of
the fixed tail at the back of the machine, and causes it to rise or
fall. Moving the same lever from side to side warps the rear surfaces
of the supporting planes. The act of pushing from side to side a bar on
which the aviator’s feet rest puts the rudder into action and steers
the machine.

The triumphs of the Blériot monoplane would fill many pages. It was
the first machine to fly over an expanse of water--the Channel. Later,
it carried M. Prior from London to Paris without a stop, traversing
250 miles in three hours 56 minutes, beating the performances of the
fleetest express trains by three hours. If it no longer for the moment
holds the record of height, which it has so often done, it carried M.
Garros up to a height of 5,000 metres. When his engine broke down at
that prodigious height, by its superb gliding powers it brought him
safely to earth!

It has flown over the Alpine peaks! It carried the first aëroplane
post--1,750 letters and cards--from Hendon to Windsor in seventeen
minutes!

In 1911 Blériot No. XI. flew with ten persons on board.

Its past records have indeed fitted it to be a military machine. It
is doubtlessly destined to play an important rôle in the present war
in the hands of the French aviators. Especially suitable is this type
for the one-seated military machine. Often it may be desirable to
employ a two-seated machine to carry pilot and observer; but there is
often, too, a use for the single-seated type of machine flying at a
rate of some eighty miles an hour. The work of these observers is to
make swift dashes over the enemy’s lines, make a speedy reconnaissance
of the enemy’s position, and return at once to headquarters with what
information has been obtained.

The following are the dimensions, etc., of the 1914 type of armoured
Blériot monoplanes:--

  Length      6.15 metres
  Span        10.10 metres
  Area        19 sq. metres
  Motor       80 h.p. Gnome
  Speed       100 km. per hour


THE ANTOINETTE MONOPLANE.

There is another monoplane that will figure in the history of
aëronautics--the Antoinette monoplane. This was the first flying
machine to fly in a wind. Up to the time that Mr. Latham went to the
flying meeting at Blackpool, which took place almost immediately after
the famous Rheims meeting, aviators had only dared to fly in calm
weather. On the flying grounds there used to be tiny flags on posts.
When the flags hung down limply that was the time for flying. When they
moved about, even languidly, that was the time to put the aëroplane
to rest in its shed. Aviators then underestimated the capabilities of
their own machines.

When the aviators came to England the island breezes kept the little
flags vigorously moving about. The aviators were consternated. The
public was disappointed. It began to regard flight as a calm-weather
business. Aëroplanes could not face one breath of wind! Of what
practical use would they ever be!

Latham at that time had his Antoinette monoplane at Blackpool. It
consisted of large and strongly built wings, giving a surface of
about 575 square feet, set at a dihedral angle. The motor was some
60 h.p. At the back of the body of the machine were fixed horizontal
and vertical fins. There were hinged horizontal planes at the end of
the tail for elevating or lowering the machine. “Ailerons” were used
on the main surface for controlling lateral stability. One day, at
Blackpool, Latham went up in a very high wind, and remained in the
air for a considerable time. How much of the stability of his machine
was due to his dexterity, or how much to the machine, it is difficult
to say. Probably the fact that the wings were set at a dihedral angle
had much to do with it. He also had a much larger horse power than his
contemporaries, which no doubt contributed to his success. Anyhow, by
the Antoinette monoplane flight was redeemed from the reproach that
it was merely a pastime for ideal weather conditions. From that time
aviators have sought the winds as well as the calms. Now aircraft can
fly in winds of forty-eight or even fifty miles an hour! This step
of Latham gave a great impetus towards the military adoption of the
aëroplane. The military and naval mind tends to despise what is only
of use in the most favourable conditions. It had put aside the airship
till it could combat moderate winds. It did the same with the aëroplane.

The Wright, Farman, and Blériot machines may be described as the
parent types from which have sprung the large variety which at the
present time are at the disposal of the aviator. Amongst the various
types which have sprung from the parent forms we search in vain for
any underlying new principles, if we except the Dunne machine. There
is, however, in the various types plenty of variety of constructional
detail. Perhaps the two most important features of modern aëroplane
work are (1), the gradual substitution of steel in place of wood, and
the general strengthening of aëroplane construction; (2), the armouring
of vital parts of aëroplanes for the exigencies of warfare. Of this
latter innovation mention will be made later. Regarding the various
types of machines now available, it must suffice in this chapter to
especially mention a few which have features of special interest for
the purpose of warlike operations.

The success of the operations of the British aëroplanists in the war
is evidence of the efficiency of the apparatus being used. The British
military aëronautical authorities have evolved a very useful form of
aëroplane. In present circumstances, however, detailed description of
this must be omitted.


WEIGHT-LIFTING MACHINES.

i. _The Cody Biplane._--The Cody type was quite an experimental
machine. It should not, however, be without notice, as it was an early
effort towards the production of weight-lifting machines. These, in
the future, will have to be evolved if the aëroplane is to take a
large part in offensive operations. Scouting and offensive work call
for different types of machines. The Cody biplane had the largest
supporting surface that has been made, excepting that of Sir Hiram
Maxim’s flying machine. The two main surfaces were 52 feet in length,
7 feet 6 inches wide. They had a supporting surface of 775 square
feet. But this was small compared with the Maxim giant, which spread
4,000 square feet of surface. In the Cody machine the front elevators,
which bore some of the load, alone represented 150 square feet. The
two vertical rudders were at equal distances fore and aft of the main
supporting surfaces. A distinctive feature was the elevator. This was
in two separate parts, each of which could be moved independently
of the other. Cody adopted the method of the brothers Wright for
attaining lateral stability and steering--warping the main surfaces.

There were vertical and horizontal rudders operated by a single
steering wheel. Cody used generally an 80 h.p. engine, but in some of
his experiments he went up to 130 h.p. A peculiarity of the screws was
their greater width at the base than at the tips. The weight of the
machine was about one ton. Though it was such a large machine some
attempts were made to give it portability. The two ends of the main
decks, each 16 feet long, were removable. The girder supporting the
elevator could also be detached, as the rear rudder frame was made to
fold back against the body. With this machine Cody flew at excellent
speeds, averaging fifty miles an hour. On one occasion he was credited
with seventy miles an hour.

It was the Cody machine which won the first prizes which were open to
the world at the military trials in 1912. Of all the earlier practical
fliers in this country no one perhaps did so much to popularise flight
as Cody. His pluck and perseverance, despite the constant disasters
that were his lot, gained British appreciation, and all recognised that
if he was not a man of letters he was one of intuition. His well-known
man-lifting kite, unequalled indeed for the purpose for which it was
designed, was an example of the illuminating flashes that were wont to
cross his brain. It was not the product of calculation, but the happy
thought.

ii. _Maurice Farman Biplane._--A type of weight-carrying machine that
has survived is that designed by Mr. Henry Farman’s brother, Mr.
Maurice Farman. This machine has extensions to its main surfaces,
which enable it to carry a considerable weight. It has been found
capable of remaining in the air a very long time, which is an important
consideration for war use, especially when the aëroplane is on the
offensive. It is capable of flying at a very low speed. A disadvantage
is that it requires very skilful piloting, especially when used in high
winds.


THE BREGUET BIPLANE.

Very conspicuous in the Paris Salon exhibitions has been the Breguet
biplane. This is one of very advanced type; it is a military machine
_par excellence_. Simplicity and portability throughout are its
distinguishing features, and these are the essence of a machine
designed for war. One might almost call it a combination of monoplane
and biplane construction. There is the familiar tapering of the
framework, with controlling planes at the end, such as in the Blériot,
but two superposed planes, instead of the bird-like projecting wings
of the Blériot, are above and below the body of the machine. Steel
enters largely into the design. There is a maximum of supporting struts
between the main surfaces. These are constructed with thin metal
ribs, and are therefore flexible, an exceedingly important feature,
rendering the machine exceptionally stable in high and gusty winds.
For portability the main surfaces can be taken out of position in a
few minutes. By the excellent method of hinging the planes to the body
of the machine the former may be turned back and folded up beside the
body of the machine. The aëroplane can therefore be described as a
folding-up one. It can therefore travel on the road like a motor-car,
instead of having to be packed up and conveyed in a wagon. This method
of road conveyance would be impracticable with a machine with its wings
outspread.


THE SHORT DOUBLE-ENGINED AËROPLANE.

How many times have engines failed during flight on both monoplanes
and biplanes! How many tragedies have thus been enacted! Time and
experience indeed have mitigated this type of aërial disaster. The
improvement in engines has been one cause of salvation in this respect,
the practice of vol-planing the other. But even now from the seat of
war comes the news of engines that fail and machines that drop into the
realm of the enemy. The old proverb of having two strings to one’s bow
should apply to aëronautics.

The desideratum, indeed, is the duplication of such a vital part as
the motor. Considerations of weight have been the hindrance to engine
duplication. Mr. Short has given very special attention to this
matter, and has designed what appears to be an excellent machine,
undoubtedly of military value. The biplane is supplied with two Gnome
motors. One drives the screws in the front of the machine, and placed
a considerable distance apart. The other drives a single screw behind
the planes. In the ordinary way both engines run at moderate speed, but
if one fails the acceleration of the speed of the other will keep the
machine flying.


THE VENDÔME MONOPLANE.

A monoplane which has repute in France for strength, general aptitude,
and convenience is the Vendôme type. It has been especially commended
by experts on account of the quickness with which it can be put
together and dismantled. The only criticism to which it has been
exposed is, perhaps, that it is a little too strong for requisite
lightness, and that a modification of the metallic portions might
reduce weight without sacrifice of efficiency. This machine throughout
is made of hickory wood.


BREGUET-BRISTOL BIPLANE.

This is one of the newest machines France has at her disposal. It is a
happy combination of British and French make, due to the collaboration
of two firms, the Bristol Company and La Société Breguet.

The result of the combination is said to be eminently satisfactory. A
distinguishing feature of this machine is rapid dismantlement. There
are two pairs of wings. These are identical, interchangeable, and
connected in each case by a flexible partition, which permits of the
wings being laterally straightened up. The area of this interesting
machine is 39 square metres; length, 8.90 metres; span, 11.50 metres.


THE DESTROYER NIEUPORT MONOPLANE.

During this year, even before the outbreak of war, the aëroplane
had been well armoured and armed. A striking example of an armoured
air-scouting machine is the Nieuport monoplane. This type has obtained
brilliant result. Equipped with pilot, bombs, and armament it has
flown at the rate of 145 kilometres an hour, risen at the rate of 500
metres in 3 minutes 45 seconds, made its departure and landed within an
enclosure of 150 square metres.

This monoplane has 24 square metres of surface, and weighs more than
1,000 kgs. The armoury is carried out by a cuirass of steel or nickel
plates, which cover the vital front parts and the place where the pilot
sits.


ARMOURED CLEMENT-BAYARD MONOPLANE.

This new type is exceedingly well armoured, the protective caps
covering the motor and the middle of the machine.

The following are the dimensions, etc.:--

  Length      5.60 metres
  Span        9.50 metres
  Area        18 sq. metres
  Motor       100 h.p. Gnome
  Weight      415 kgs.
  Speed       150 km. per hour

On June 6th last the French military aviators with their armoured and
armed aëroplanes were reviewed at Villacoublay by General Joffre and
General Bernard, the director of military aëronautics. Amongst the
types of aëroplanes present was the Dorand biplane, having two Gnome
motors driving separate screws, armoured in its vital parts, and
armed with a Hotchkiss mitrailleuse. This was mounted on a pivot,
and could be fired in almost every direction. There were, too, the
Morane-Saulnier, Blériot-Gouin, Nieuport, and Breguet-Bristol types.

M. Raymond, in his speech before the Senate in February last, said
that Germany was in possession of armoured aëroplanes, but that France
had none. The June review at Villacoublay showed what vast strides in
military aëroplane construction the French had made in a few months.

The French military aëroplanes consist of Farman types, and many other
leading French forms. In 1913 there were about 500 French military
aëroplanes and a few naval hydroplanes.

France manufactures a great number of aëroplanes, of late years about
1,000 per year. These include Government machines, those of private
owners and export machines. There are at least twenty-nine French
flying grounds, many of them flying schools and trial grounds of the
leading French airship and aëroplane makers.

In 1913 Italy appears to have had about a hundred military aëroplanes,
including those on order, Blériots, Bristol (monoplanes), Farmans,
Nieuports, and others. She had six or eight naval aëroplanes. She is
well provided with military flying schools and other flying grounds,
nearly all fitted with hangars.

There are military airship hangars at Rome, Milan, Verona, Venice, and
Bracciano.

Belgium has a military school of aviation near Antwerp, and in 1913
she had as many as twenty-four military aëroplanes--H. Farman, 80 h.p.
Gnome. There are in Belgium about half a dozen flying grounds, and as
many aërial societies or clubs.

As already stated, Germany, in the first instance, looked to
Austria-Hungary for her aëroplanes, and the Etrich was an Austrian
machine. In late years, however, Austria’s aëroplanes were mainly
Lohners; the Government favoured this make and discouraged others,
consequently enterprise and invention languished. After the accident to
the Aspern the Lohner was condemned as of too feeble a resistance, and
meanwhile discouragement had effaced all the other systems.

Aëroplanes are used both in the Russian army and navy. Those of the
navy are hydro-aëroplanes, or capable of being so arranged. In number,
the Russian navy has about a dozen. Of military aëroplanes Russia has
probably from 250 to about 300, many of them of modern type, and built
in Russia, the principal types being Rumpler, Albatross, Aviatik,
Nieuport, Farman, Bristol and Deperdussin.

Bulgaria has a number of aëroplanes, mainly Blériots and Bristols.


SYKORSKY’S GIANT AËROPLANE.

A very remarkable type of aëroplane is the giant biplane invented by
the Russian aviator Sykorsky. It doubtless marks the beginning of
a new era in the construction of machines on the heavier-than-air
principle. Most aviators have shirked the use of a machine that could
carry a large number of persons. It would seem that Russia is destined
to take the lead in this class of machine, which may before long put
the lighter-than-air Zeppelins entirely out of date. The machine
of Sykorsky is not, indeed, a mere project, but a reality, for at
Petrograd on February 25th, it flew for eighteen minutes with sixteen
passengers on board. They represented a weight of 1,300 kilogrammes.
The height attained in this flight was 300 metres. On February 27th the
machine flew from Petrograd to Tsarskoe Selo and back again, taking
nine persons, in two hours six minutes, at a height of 1,000 metres.
The performance constituted a triple record of distance, height, and
duration of flight with nine persons on board.

The following are the dimensions, etc.:--

  Length                         20 metres
  Span                           37 metres
  Surface                        182 sq. metres
  Distance between planes        2.80 metres
  Motive power                   4 Argus motors (100 h.p. each)
  Weight of motors               220 kgs.
  Weight of machine without
   passengers                    3,500 kgs.
  Weight with 16 passengers      4,800 kgs.

The motors are placed in groups of two on each side of the body of the
machine. Each pair works a screw and each individual motor can be put
into action and stopped separately. The body of the machine contains a
chamber for the pilots three square metres in size, a passenger salon
of five square metres, and two other chambers of three and two square
metres respectively. The whole are lit by four windows on each side.
The rooms can be artificially lighted by electricity and warmed by
motor gas. There are, indeed, future possibilities for such a machine
in war!

I have mentioned that the type of aëroplane devised by Lieutenant Dunne
is characterised by a distinctive principle of its own. The claim is
made that it is automatically stable. It has, however, rather a claim
to “inherent stability” than “automatic stability,” if we accept the
terms as Professor Bryan has defined them.

The following details appeared in the “Aëronautical Journal”:--

    The salient features of the machine are the backward slope of the
    planes, which, in plan view, form an angle with the apex in the
    direction of flight, and the absence of a tail or supplementary
    planes of any description. The following are its chief
    dimensions:--Span, 46 feet; length (fore and aft), from apex to
    rear wing tip, 20 feet 4½ inches; length of body, 19 feet; surface,
    500 square feet; weight (including pilot and six gallons of
    petrol), 1,700 lb.; engine, four-cylinder 50–60 h.p. Green, 1,100
    r.p.m., driving twin propellers placed one on either side of the
    body in the rear.

    The weight in flight being 1,700 lb., the aëroplane carries a load
    of about 3 lb. per square foot. The speed in flight averages about
    40 m.p.h.

    The chord of the surfaces is even throughout--6 feet; the vertical
    distance between the surfaces is also constant at 6 feet; at
    either extremity a vertical curtain is placed between the surfaces
    to prevent leakage of air sideways. The surfaces slope back from
    the apex at an angle of 58° on either side, the rear wing tips,
    therefore, actually being in the rear of the aft end of the body,
    and the entire outer extremities of the wings lying back well
    behind the centre of gravity.

    The curve or camber of the planes is not uniform, and, briefly,
    it may be said that each wing may be viewed as a portion of the
    surface of a cone with the apex to the rear. A consequence of this
    is that the angle of incidence of each wing gradually decreases
    from the root to the tip; so much so, that while the angle at
    the root is positive, that at the tip is distinctly negative,
    the difference in the respective angles being 45°. Apart from
    this, an interesting feature is the extreme downward bend of the
    _trailing_ edges over a short distance where the two surfaces
    meet in the centre; this arrangement has been adopted chiefly
    to enable the aëroplane to right itself naturally in the event
    of its having assumed a vertical position in the air. A further
    interesting consideration is that this machine is the only one
    that could safely be forced backwards. It may be added, briefly,
    that the loss in efficiency arising from the negative angle of the
    wing-tips is compensated by the backward slope and angle of the
    surfaces, which naturally causes the flow of air to be depleted
    outwardly beneath the planes, and even induces a certain amount of
    compression beneath the outer ends. The body is entirely covered
    in; the pilot’s seat is in the prow; the motor further to the rear.
    The centre of gravity is well forward, and about six inches above
    the lower plane. The propellers are carried on a transverse girder,
    and are chain-driven in the same direction--contra-clockwise
    viewed from the rear. The centre of the boss is situated 1 foot
    2 inches above the lower plane, and 4 feet from the central axis
    of the machine. The propellers, designed by Capt. Carden, are
    of solid wood, 7 feet in diameter, 7 feet 6 inches pitch, each
    weighing 21 lb. The chassis comprises two main wheels, with a small
    wheel-and-skid fore and aft. The system of controls is extremely
    simple. The trailing edge of each extremity of the upper plane
    forms a hinged flap, measuring 7 feet 2 inches by 1 foot 9 inches.
    These are independently controlled by two levers, one on either
    hand of the pilot a couple of mirrors allow the pilot to ascertain
    the working of the steering-flaps when in flight. The throttle
    control is fixed to the right-hand lever.

On several occasions, while flying on this machine, the pilot used both
hands for writing and making notes, leaving the machine uncontrolled,
and came down with his hands raised above his head.

Germany has many forms of aëroplanes, and these will be treated of in
the next chapter.

[Illustration: _AVIONS ALLEMANDS_

  TIREZ
  sur ces Appareils

  MONOPLAN TAUBE

  TAUBE

  MONOPLAN GOTHA

  GOTHA

  MONOPLAN RUMPLER

  RUMPLER

  BIPLAN ALBATROS

  ALBATROS

  ZEPPELIN

A DIAGRAM ISSUED BY THE FRENCH WAR OFFICE FOR THE GUIDANCE OF THE MEN
IN THE TRENCHES.

It gives a silhouette of some Aëroplanes and an Airship in the German
service, and bears the injunction--“German Aëroplanes--fire on these
machines.”]




CHAPTER VIII

GERMANY’S AËROPLANE EQUIPMENT


The history of Germany’s developments in aërial navigation on the
heavier-than-air principle during the last few years is the history
of preparation for war. France was, indeed, the first nation to
realise that though there was a war use for the aircraft on the
lighter-than-air principle there would, in time, be no comparison
between the advantages of aëroplanes over airships.

Directly aërodrome performances were replaced by cross-country flights
that gave opportunities for the attainment of those records in
distance, height, and speed which have made the aëroplane the marvel
of the twentieth century, France vigorously attacked the problem
of turning out machines specially adapted for military purposes.
In 1910, France held the position of being the only nation who
possessed military aëroplanes to any great extent, having no less than
thirty-five. It may be noted that in that year the British Government
only possessed seven. It was in October, 1911, that the magnificent
tests carried out at Rheims taught the world the importance of the
aëroplane as an arm of war. It was those tests which woke up this
country to the fact that it was ignoring the greatest military arm of
the future. It was those tests that made Germany, ever on the alert to
increase and intensify her war weapons, determined to leave nothing
undone to set herself in the van of progress! Germany, therefore, set
to study the aëroplane especially from the military point of view,
and determined to build aëroplanes which should embody simplicity,
strength, high speed, and weight-carrying capacity. Early in 1911
Germany could boast of the possession of nearly fifty military
aëroplanes, and from that time forth she has been rapidly increasing
the number. The number of aëroplanes in Germany now available is
variously estimated; it is stated she has 500 quite modern military
aëroplanes, a number of older ones, and about 100 privately owned;
others assert, however, that Germany now has as many as 1,500 in the
country.

In Sir John French’s report, mentioned in the introductory chapter, he
tells us that our own Flying Corps in the present war were exposed to
the shot of friend as well as of foe. As the German aëroplanes have
a more or less distinctive appearance, it seems probable that these
peculiar shapes were not well known to our troops at the beginning
of the war. Such a knowledge would protect the aëroplanes of the
Allies from being mistaken for those of the enemy. The shape of a bird
has been very generally adopted for the German flying machines. The
monoplanes are specially given the form of a bird flying with wings
stretched out and tail distended, the ends of the back portion of the
wings projecting beyond the central part.

The biplane frequently presents in front an arrow-like appearance, and
the upper plane is bird-shaped. It will certainly be incumbent upon
us to ascertain, for the future development of flying machines, how
far the adoption of this natural bird-shape influences speed, etc.
The tables on the opposite page will give some idea of the aëroplane
equipment the Germans possessed at the beginning of the war.

Regarding the various types of German aëroplanes, it must suffice to
enumerate a selection.


THE ETRICH MONOPLANE.

This was the forerunner of the German monoplanes, and very
representative of German type. These machines were first made in
Austria, and are excellent examples of strong, simple, efficient
military aircraft. The wing-shaped supporting planes have upturned
wing tips at the back, which are flexed up and down for the purpose of
lateral stability; the back portion of the tail plane is movable, and
can be flexed for elevating.

Regarding the other types of German machines, Germany appears to have
gone through three stages of construction: 1. The stage in which
the types evolved were chiefly copies of various well-known French
machines. 2. That in which a characteristic German type was produced,
the Taube (dove), a type which possessed many excellent qualities, but
also several defects.


SOME GERMAN BIPLANES.

 --------------+-------+-------+--------+--------------------------+-----------
               |       |Length | Area in|                          | Speed by
    Make and   | Span. |  in   |metres².|      Engine and h.p.     |the hour in
      Type.    |       |metres.|        |                          |kilometres.
 --------------+-------+-------+--------+--------------------------+-----------
 L.V.G., 1913  |14·9 m.| 9 m.  |  44 m. |Argus or Mercèdes 100 h.p.|  100 km.
 Otto          |14·9 m.|10·8 m.|   --   |         100 h.p.         |  100 km.
 Albatross     |14·4 m.| 9·2 m.|   --   |Argus or Mercèdes 100 h.p.|  110 km.
 Rumpler Taube | 13 m. | 8·5 m.|  38 m. |    Mercèdes 100 h.p.     |    --
 Aviatik       | 16 m. |10·8 m.|  43 m. |Argus or Mercèdes 100 h.p.|  100 km.
 --------------+-------+-------+--------+--------------------------+-----------


SOME GERMAN MONOPLANES.

 --------------+-------+-------+--------+--------------------------+-----------
               |       |Length | Area in|                          | Speed by
    Make and   | Span. |  in   |metres².|      Engine and h.p.     |the hour in
      Type.    |       |metres.|        |                          |kilometres.
 --------------+-------+-------+--------+--------------------------+-----------
 Rumpler Taube,|       |       |        |                          |
   1913–14     | 14 m. |10·2 m.|  35 m. |    Mercèdes 100 h.p.     |  120 km.
 Kondor        | 14 m. | 9·8 m.|   --   |    Mercèdes 100 h.p.     |  120 km.
 Albatross     |       |       |        |                          |
   (Hirth Type)|14·6 m.| 10 m. |  35 m. |    Mercèdes 100 h.p.     |  105 km.
 Etrich Taube  |14·3 m.|9·85 m.|  38 m. |Argus or Mercèdes 100 h.p.|  105 km.
 Gotha Taube   |14·4 m.|10·2 m.|   --   |Argus or Mercèdes 100 h.p.|  100 km.
 --------------+-------+-------+--------+--------------------------+-----------

3. That in which the indifferent qualities of the characteristic type
were removed.

Of the first type may be mentioned the Euler, which is a modification
of the Voisin; the Otto, which embodies the H. Farman principles; the
D.F.W. (Deutsche Flüggen Werk); some of these are practically H. and M.
Farman biplanes. They also include a rapid type, called Mars biplanes,
in which the main surfaces are shaped like those of the famous Nieuport
machine.

Amongst the more distinctive machines are


THE AVIATIK BIPLANE.

This is one of the most noticeable of German machines. A special
feature is the space provided in the front part of the fuselage, which
gives the observer every opportunity of free movement for scouting,
writing, photographing, and throwing bombs. The vital parts and front
are well fortified with a metallic “capot,” and the rest of the
fuselage is also armoured. The rapid erection and dismantling of
this machine has been especially well planned. The supporting surface
consists of two planes of unequal dimensions, the upper one being
the larger. Each is divided into two sections fixed independently
on the fuselage. The planes are coated with a liquid to render them
incombustible. The longitudinal stability is assured by a fixed plane
prolonged by a rudder for controlling the vertical movements. Two large
“ailerons” at the back of the upper planes are provided for lateral
stability.

[Illustration:

                                                     [_Topical Press._
  A RUMPLER MONOPLANE (A TAUBE),

showing the distinctive bird shape so affected by the German monoplane
makers.]

Steering is effected by a vertical rudder placed between the two
portions of the horizontal plane rudder. The dimensions of one type of
the Aviatik can be seen in the table of types of German aëroplanes.


THE RUMPLER MONOPLANE.

In this, as in all the Taube flying machines, the wings are in the
shape of a dove or pigeon. The end of the wings are flexible. The
stability of the apparatus is assured both by the shape of the wings
and their flexibility. It is at once a combination of the inherent
stability type and that depending on the warping of surfaces; the
advisability of blending the principles is one practice alone can
decide. In some of the Rumpler monoplanes, instead of the ends of the
wings being flexible, there are “ailerons” attached.


THE RUMPLER BIPLANE.

This biplane with the Aviatik is remarkable for the amount of space
provided for pilot and observer. The fuselage is protected in front
with aluminium. The upper plane is not made to join in the centre, as
in most German machines; instead, there is a short immovable central
plane, which is permanently attached to the fuselage by four tubes; to
the ends of this central plane, on either side, the other planes are
fixed.


THE ALBATROSS.

This is a successful and much used German type, made at Johannisthal,
near Berlin; about two hundred of these machines were made in 1913.
The German Government have a great number of Albatross biplanes and
monoplanes (Taube), and also several Albatross waterplanes. There
appear to be four improved Albatross types for this year, two of them
biplanes, one waterplane, and one monoplane (Taube), all with Mercèdes
100 h.p. motors, capable of attaining a maximum speed of 65 to 68
m.p.h. The biplane types are just over 26 feet in length, while the
waterplane and monoplane average 29¼ feet.

The Germans have not favoured rotary engines and have almost
exclusively adopted those with stationary cylinders, but an exception
has been made in the case of the Sommer arrow-shaped biplane.

Another feature of German machines is that they are all, with one
exception, double seated, the extra swiftly dashing scouting monoplane
does not seem to appeal to the German. We find, however, one exception
to the rule: the Argo type of monoplane is a one-seated machine. It
has a span of 9 metres, surface of 15 square metres, and speed of 130
kilometres per hour.

A feature of aviation in Germany during the last few years of peace has
been the night flights. For these, they have made special provision
in the shape of aërial lighthouses, scattered all over the country.
Some of these are electrically lighted, others by acetylene; some
are “Morse” fires; some are fixed, others revolve, and the nature of
the light has a distinct meaning, such as “near is a high tower to
be avoided,” and so on. Germany is alone amongst the nations in her
appreciation of the necessity of aërial lighthouses.

Round Berlin there are six such stations at, respectively: Nauen,
Döberitz, Tegel, Reinickendorf, Linderberg, and Johannisthal; and there
are also aërial lighthouses at the following places:--Königsberg,
Posen, Liegnitz, Dresden, Belgern, Eilvese, Gotha, Weimar,
Schleissheim, Strasbourg, Grosser-Feldberg, Berncastel-Cues, Metz, and
Bonn.

Besides building aircraft on the lighter-than-air principle, Germany
has not been idle in their use during the last few years of peace.
She has German military flying schools, seventeen in number. They are
as follows, arranged alphabetically:--Darmstadt, Döberitz, Freiburg,
Germersheim, Graudenz, Hannover, Güterbog, Köln (Cologne), Königsberg,
Metz, München-Oberschleissheim, München-Oberwiesenfeld, Posen,
Saarbrücken, Schneidemühl, Strasbourg, and Zeithain.

There are three naval flying schools, at Kiel, Danzig, and
Wilhelmshaven, and about three dozen seaplanes, mainly
biplanes--Rumpler, Albatross, Curtiss, etc.

There are also in Germany no less than eighty-eight civilian
aëronautical bodies, many of whom possess flying grounds, and there
must be at least between thirty and forty of these private flying
grounds, in addition to those of the military schools.

M. Raoul Volens, in his lucid articles, has pointed out how Germany,
who was in 1911 so much behind France, has been able to produce by
1914 an equipment that rivals hers. He points out that in the Imperial
manœuvres of 1911 it was with difficulty that Germany could produce
eight aëroplanes; in 1912 she produced eight squadrons; at the end of
that year 230 certificates had been granted to pilots by the German
Aëro Club; in 1913 the number was 600; in 1912 the number of flying
machine manufacturing firms was twenty; there were fifty in 1913. The
number of flights made in Germany in 1911 was 7,489; in 1912, 17,651;
in 1913 it was 36,817.

In 1911, the total duration of flights was 821 hours 41 minutes; in
1912, 1,966 hours 3 minutes; in 1913, 4,096 hours 48 minutes.

The progress made appears to have been largely due to the efforts of
the German National Aërial League, which collected 7,234,506 marks,
to be spent on aëronautical development in a few months’ time. The
Council of the League made a very practical plan for acquiring a large
number of pilots, and at the same time developing the most efficient
class of machine possible. They left the training of the pilots to the
manufacturers, giving them grants for each qualified pilot they had
trained.

They also adopted the plan of giving premiums to pilots who
accomplished certain practical flights of the nature of what would be
required in war. For instance, if a pilot flew for an hour without
a drop, he received 1,000 marks; if he made the flight outside an
aërodrome, and was accompanied by a passenger, he received an
additional prize of 500 marks; for a flight of over six hours, a
monthly sum of 2,000 marks was given to a pilot who flew the longest
distance without descending for as long as he held the record.

Regarding the development of aëronautics in Germany, it is interesting
to note that just before the present war broke out two world records,
those of height and duration of flight, were won by Germans; up to this
year they had been held by France. These were the last victories of
peace! On July 14th last Herr Oelerich rose from Leipzig-Lindenthal at
3.45 in the morning on a D.F.W. biplane, military type, furnished with
a Mercèdes motor of 100 h.p., and attained an altitude of 8,150 metres.

On July 10th last, Rheinold Boehm rose from the Johannisthal Aërodrome
at 5.54 a.m. on an Albatross biplane of military type, furnished with
a Mercèdes motor of 75 h.p. He flew round about Berlin. During the
night-time the aërial lighthouses indicated to him his whereabouts.
He did not touch the earth till 6.12 p.m., having been in the air
for twenty-four hours and twelve minutes. It is curious to note in
what regular progress the records of duration had been won this year.
On February 4th the German Langer flew continuously for 14 hours 7
minutes. On February 7th the German Langer had flown for 16 hours 20
minutes. On April 8th the Frenchman Poulet had flown for 16 hours 28
minutes. On June 22nd and 23rd the German Basser wrested the record
away from Poulet, and accomplished 18 hours 12 minutes. Then the German
Landmann on June 27th and 28th beat his countryman with the record of
21 hours 50 minutes. Then came the final exploit of Boehm, which has
been recorded above.




CHAPTER IX

THE FIRST USE OF THE AËROPLANE IN WAR--TRIPOLI--THE BALKANS


Manœuvres in peace were the first practical test of the value of
aëroplanes in war. The French proved their efficiency in their
manœuvres in Picardy as long ago as 1910. The result of their use was
a surprise for the military authorities themselves. Before the test it
had been considered that an observer in an airship which could hover
over the lines of the enemy or over a fortification would have a good
chance of being able to bring back to headquarters useful details of
what they had seen; but it had been thought by many military experts
that the aëroplanist from his forced, rapid movement would not be able
to form a mental picture of what actually passed his eyes, that if
the retina had recorded the fleeting image on the brain, there would
be confusion. The success of the aviator was an example of the truism
that experience often does not coincide with preconceived opinion,
for the reason that some unknown factor exists, and is only brought
to light by the special circumstances of the case. Of all people, the
aviator is one who constantly practises sharpness and concentration
of sense; his eye and brain have a perpetual habit of harmonious and
close-bound working; time to him has an enhanced value; none, like
he, has ever learnt the exigencies of the minutes. His whole system
becomes acclimatised to the constant maintenance of the equilibrium
of his powers, for he has realised that for any negligence he will
pay the death penalty. Is it wonder then that the glance of the
practised aviator over the far-stretching regions beneath him becomes
super-sight? So is it that the best aërial observer is often one who
combines in himself the varied occupation of engineer, pilot, and
scout, and who in his swift machine, arrow-like, darts above the enemy.

In the case of the military machines at the French manœuvres above
mentioned, the work of pilot and observer was often divided; and it was
found that the observer generally required some familiarity with flight
before acquiring the requisite sharpness of vision.

Generally speaking, in the manœuvres, the information brought back was
clear, defined, decisive. The intelligence brought back by cavalry
scouts has sometimes been a puzzle to the generals in command--hints
suggesting to them probabilities, perhaps, rather than accumulated
certainties. But the air scouts brought such definite statements as
these: “Have seen infantry hidden in a wood,” “A squadron with machine
guns are marching towards ----,” “Seen a company digging trenches at
----,” “The enemy are in full retreat,” etc.

The value of the new arm was manifest in this country in the very
first manœuvres in which aëroplanes were used; by its use the plans
made were all rapidly discovered and rendered useless! Plans made on
the old principle of fighting in the dark, each side ignorant of the
operations of the other, fell through once and for all; and it became
recognised that the coming of the aëroplane meant the revolution of the
methods of conducting war.

But if from the experience of manœuvres the value of aëroplane
reconnaissance was patent to expert military authority, the public
generally did not realise the value of the new arm until it had been
tried in something beyond mimic warfare. This occurred in the Italian
war operations in Tripoli. In this war the need of reconnaissance was
great; operations had to be carried on in a difficult country, and with
an enemy that adopted “tricky” forms of warfare. To Italy belongs the
credit of being the first nation to put aëroplanes to the test in war,
both for reconnaissance and offensive purposes. The types of aëroplanes
used in this war were chiefly Blériot and Nieuport monoplanes; one
Etrich monoplane was also included.

Very valuable information was acquired on several occasions by the
air scouts, who flew over wide tracts of desert, marking the position
of Turks and Arabs, and ascertaining their movements preparatory to
making attacks on Italian positions. The aëroplanes were fired upon
by the enemy, and sometimes the wings of an aëroplane were riddled
by shot without resulting accident, proving that the riddling of the
wings, so long as sufficient supporting surface remains, is not the
greatest evil to be feared. On one occasion Lieutenant Rossi, while
making a reconnaissance, nearly fell into the hands of the Arabs. The
motor suddenly stopped, and his machine was rapidly falling; the motor,
however, recovered just in time for the aviator to remain in the air,
and he was able to return to Tripoli.

Regarding the offensive use of aëroplanes in this war, it was related
that Lieutenant Gavotti threw from his machine upon an Arab camp a bomb
made of picrate of potash; he was at the time 700 feet above the oasis
of Aïn-zara, when he discovered beneath two masses of Arabs, numbering
each about 1,500 men. He took out the bomb from a bag at his side
with one hand, while with the other he manœuvred the machine, and as
he passed over a group of Arabs he dropped the bomb. He could follow
its course for a moment or two while he was passing over the bright
green verdure of the oasis, but it was speedily lost to sight, while
the noise of the motor prevented his hearing the explosion below. He
saw, however, a cloud of smoke and the Arabs flying in all directions.
This was the first instance on record of bomb throwing from aircraft.
Gavotti was himself of opinion that in bomb throwing the operation
should be carried out with the aid of two aëroplanes; the one in
advance should throw the bomb, the one following observe the result.
The one in advance would have to fly at a lower level so as to drop
the bomb; the observer following would fly much higher. The dropping
of the bomb in this case produced excellent moral effects. When, on
a later occasion, the aviators revisited the same spot, there was no
trace of Arab encampments. On another occasion Captain Moizo threw two
bombs into the Turkish camp near Aïn-zara, which also had the effect of
putting the Turks to flight.

A troublesome feature of flight over sandy deserts is found to be the
intrusion of sand into the valves and bearings of the engines; but
if aëroplanes can be armoured against shot, doubtless a sufficiently
light and effective means of protecting the engines against sand can be
devised.

Use of aëroplanes was also made in the Balkan war; and it may be noted
that before that war broke out Germans went to instruct the Turks in
bomb throwing from aircraft. Bulgaria had a hastily formed aviation
corps, and it showed itself useful.

It is, however, in the present European war that the large-scale use of
aëroplanes is being daily more and more manifested.




CHAPTER X

THE NEW ARM IN ARMAGEDDON


The question has been often asked why we were so long in this country
in grasping the necessity of keeping pace with other countries by
having a national flying corps? In an introductory chapter I have
stated that a want of public interest was the cause of British
dilatoriness in aëronautical matters; but there was also another very
potent reason--a meteorological one. From the weather point of view,
the conditions for practising flight in this country cannot be compared
with those obtaining on the Continent. Our insular position affords an
uncertainty of wind force that in the earlier days of the aëroplane
would have been fatal to progress had the pioneers chosen this isle for
their experiments. Even while the aëroplanes were only calm-weather
machines, and even when they first essayed flight in moderate winds,
there was an undoubted instinct in the minds of an eminently practical
nation that the loss of life consequent upon a systematic military use
would be hardly justifiable. So the nation waited for a certain stage
of progress in flying machines before launching them into the winds
and gusts for serious military work. When they were first used in this
country, the nature of our climate proved exceedingly disastrous and
swelled the casualty lists of peace. Those who have survived have had
a hard and exceptionally strenuous training in the ways of the air,
ever having had to be on the alert against the ever-present threatening
blasts which tend to upset the stability of flying machines. But is
it not the exceptionally hard training that the military aviators in
this country have had to undergo that has produced the exceedingly able
and successful Flying Corps that is struggling for King and country in
the present campaign? It has been seen how they have been commended
in the first report of Sir John French. Their efforts have also met
with the greatest appreciation of the French. General Joffre in his
report specially dwelt on the regular and valuable reconnaissance of
the British Royal Flying Corps. In Sir John French’s report, dated
September 11th, the following passage appears:--

    Quite one of the features of the campaign, on our side, has been
    the success attained by the Royal Flying Corps. In regard to the
    collection of information it is impossible either to award too much
    praise to our aviators for the way they have carried out their
    duties or to overestimate the value of the intelligence collected,
    more especially during the recent advance.

    In due course certain examples of what has been effected may
    be specified, and the far-reaching nature of the results fully
    explained, but that time has not yet arrived. That the services
    of our Flying Corps, which has really been on trial, are fully
    appreciated by our Allies is shown by the following message from
    the Commander-in-Chief of the French armies, received on the night
    of September 9th by Field-Marshal Sir John French:--

    “Please express most particularly to Marshal French my thanks for
    services rendered on every day by the English Flying Corps. The
    precision, exactitude, and regularity of the news brought in by
    its members are evidence of their perfect organisation, and also
    of the perfect training of pilots and observers.”

    To give a rough idea of the amount of work carried out, it is
    sufficient to mention that, during a period of twenty days up to
    September 10th, a daily average of more than nine reconnaissance
    flights of over 100 miles each has been maintained.

    The constant object of our aviators has been to effect the accurate
    location of the enemy’s forces, and incidentally--since the
    operations cover so large an area--of our own units. Nevertheless,
    the tactics adopted for dealing with hostile aircraft are to attack
    them instantly with one or more British machines. This has been so
    far successful that in five cases German pilots or observers have
    been shot in the air and their machines brought to the ground.

    As a consequence, the British Flying Corps has succeeded in
    establishing an individual ascendancy which is as serviceable to us
    as it is damaging to the enemy. How far it is due to this cause it
    is not possible at present to ascertain definitely, but the fact
    remains that the enemy have recently become much less enterprising
    in their flights. Something in the direction of the mastery of the
    air has already been gained.

The Royal Flying Corps has already won the distinction of the Legion
d’Honneur.

The principal uses of the new arm in war may be said to be:--

  1. Reconnaissance.

  2. Directing and correcting artillery fire.

  3. Offensive operations.

  4. Rapid despatch carrying to a distance.

  5. Distributing handbills to cities.

  6. Photography.

  7. Locating submarines, mines, etc.


1. _Reconnaissance._

As a particular example of the value of reconnaissance in the present
war one may well refer to that mentioned in Sir John French’s first
report. He says, “When the news of the retirement of the French and
the heavy German threatening on my front reached me, I endeavoured
to confirm it by aëroplane reconnaissance, and as a result of this I
determined to effect a retirement to the Maubeuge position at daybreak
on the 24th.”

It is undoubtedly expedient to train aërial observers to make
reconnaissance at high altitudes. This has been the method employed
by Great Britain and France. During the present war we hear of the
British and French machines flying at 6,000 feet, where they are fairly
safe from gun-fire. The Germans often appear to fly considerably
lower. This probably accounts for the loss of so many German machines
from gun-fire. It has been stated that at the time of writing British
aviators have already brought down seventeen machines. But there
have been instances of the aëroplanes of the Allies also making
reconnaissance at lower levels. One very remarkable case of an aviator
persisting in his reconnoitring task in spite of the fire of the enemy
has been reported in the daily papers. The French aviator, M. Poiret,
who is in the Russian service, said that

    during the recent Russian-German fighting he reconnoitered over the
    enemy’s positions, with a captain of the General Staff as observer,
    at a height of 1,200 metres. He was for twenty minutes under rifle
    and shell fire. Ten bullets and two fragments of shell hit his
    aëroplane. Nevertheless, he retained his control of the machine.
    The captain was shot through the heel, the bullet coming out of
    his calf, notwithstanding which he continued taking notes. The
    aëroplane returned safely.

In making reconnaissance over the enemy’s lines it is well for the
aviator to be practised in the art of making vol-planés. On more than
one occasion in the present war the engine has failed while the aviator
has been flying over the enemy. A well-directed vol-plané has brought
him down within friendly soil. This gliding by means of gravity without
the motor working in times of peace may have been thought to be a
foolhardy practice, merely done for the sake of sensation. But the
sensation of a few years back is the necessity of to-day! The vol-plané
has become one of the most useful features of aëroplaning. A machine
that is fitted with wireless telegraphy equipment undoubtedly possesses
a great advantage for reconnoitring. It is especially useful when a
heavy attack on an enemy is in progress. By its means a continuous
stream of intelligence can be supplied to headquarters. The French have
been particularly active in the development of wireless messages from
aëroplanes, and have devised extremely portable forms of apparatus. It
will be of great interest to hear accurate information in regard to
their practical use in the present war.

Aëroplane reconnaissance in naval operations is almost equally as
important as its use on land. This will be one of the principal uses of
the hydroplane, which can either travel on the surface of water or rise
in the air. In the present war two seaplanes were recorded as scouting
near Antivari on September 8th, 1914. It is also said that the Germans
gave information to the Heligoland forts by biplanes concerning the
fight in Heligoland Bight.


2. _Directing and correcting artillery fire._

Very many reports of the use of the aëroplane in this respect have come
to hand during the present war. The Germans appear to be very keen
on this particular use. Stories told by wounded soldiers graphically
describe how with the appearance of the enemy’s aëroplane there comes
accurate and deadly fire. The Germans appear to have several simple and
ingenious means of indicating the instructions of the aërial observer
in this respect. An interesting contribution to our knowledge has been
supplied by Bombardier Smith, who was wounded by a bomb dropped from a
German aëroplane. Writing to the _Times_ he describes how the Germans
have special bombs for range-finding.

    Those bombs have proved a great success in the war, as they find
    the enemy’s ranges very accurately. The bomb when dropped leaves a
    thick, black, smoky line to enable their gunners to take the exact
    range. We were in a good position but suffered loss. The enemy
    could not find us until the aëroplane came on the scene. Then we
    had it rather hot. The gunners had to leave the guns, but later
    saved them all after being reinforced by other guns.

Another method the Germans adopt is to drop a silver ball. Almost as
the ball drops from the range-finding aëroplane, the shrapnel shell
bursts over the lines of the opponent.

They also sometimes pull up and down a little disc suspended beneath
the aëroplane. A still further variety of signalling is accomplished
by the use of lamps that are visible in daylight. Almost every method
of signalling can be used for the purpose, such as flag signalling;
wireless signals are no doubt especially effective.

I will quote from a recent article by Mr. F. W. Lanchester in
“Engineering” as to the German use of the aëroplane in this respect:--

    The value of aëroplane work will be relatively greater the longer
    the range; in fact, it may in future be found possible to employ
    heavy artillery of long range under conditions in which without
    the help of the aëroplane it would be comparatively useless. As
    an illustration, there is nothing to-day to prevent a long-range
    battery, well served by its aëroplanes, from effectively shelling
    an enemy without knowing in the least the character of its
    objective--_i.e._, whether an infantry force or position, a body
    of cavalry, or the enemy’s guns. In the present war the aëroplane
    appears to have been utilised by the German army, as a matter of
    regular routine, as an auxiliary to the artillery in the manner
    indicated. It has been reported again and again that the appearance
    of an aëroplane overhead has been the immediate prelude to the
    bursting of shrapnel, frequently the very first shell being so
    accurately placed as to indicate that the method of signalling,
    and, in fact, the whole performance, must have been well thought
    out and equally well rehearsed.


3. _Offensive operations._

This use might be well subdivided into legitimate and illegitimate
offensive operations. There has been, unfortunately, ample example
of the use of both airships and aëroplanes for purposes that are
illegitimate and barbaric in the present war. To use the advantage
of travelling in the air at altitudes for the purpose of the wanton
destruction of harmless citizens, and, further, to destroy in cities
the amassed wealth of art that only centuries, not years, produce,
is an unrighteous use of the science of aërial navigation. Before
the war it was condemned by the Hague Convention. Since, it has met
with the denouncement of all civilised nations--save the one that has
perpetrated the outrages. In the case of the aëroplane raid made into
Germany by our own British naval airmen, one party of aviators went
to Cologne to try to attack the airship halls there. The city was
enveloped with an opaque fog, and it was hopeless to try to locate the
position of the airship sheds. Though the British aviators circled
over the town for an hour and a half they refrained from discharging
any bombs, rather than run the risk of destroying civilian life or
property. An example, indeed, of the legitimate offensive use of the
aëroplane was the attempt to destroy or put out of action the very
kind of aircraft which had been so wantonly used over Paris, Antwerp,
Ostend, and other cities.

Perhaps the most important offensive use of the aëroplane is for
fighting airship and aëroplane. Mention has already been made about the
deadly character of the aëroplane when it encounters an airship. When
it meets an aëroplane the chances are more evenly balanced. Success
will depend chiefly upon the speed of the respective aëroplanes, their
climbing power, their armouring, and the guns with which they are
armed. Speed and climbing power are perhaps the greatest protective
factors. Several stories have already been told of the pursuit of
German aëroplanes by those of the Allies. The climbing power of the
machines of the latter has often been the cause of victory. It is the
well-directed shot from above to which the airman is exposed that has
ended the career of airman and machine.

At the beginning of the present chapter it was pointed out that the
British and French aëroplanes generally fly at about 6,000 feet, which
is a height fairly safe from gun-fire. While speaking of the offensive
work of aëroplanes, a few more words about the attack on them by
gun-fire may not be out of place. As Mr. Lanchester has pointed out, an
aëroplane is liable to attack by rifle, machine-gun, and shell fire.
Ordinary field artillery fire can be put out of the question in the
use of so rapidly moving a target as an aëroplane in flight. He has
estimated that an aëroplane is absolutely safe from rifle or small-bore
machine-gun fire at 7,000 feet, and it would be difficult to hit it a
thousand feet lower.

    Not only would the velocity become so reduced as to render a “hit”
    capable of but little mischief, but the time of flight of the
    bullet, rising vertically to this altitude, would be about eight or
    nine seconds, and the distance moved by the aëroplane 1,000 feet,
    more or less. Therefore, it would be necessary to fire into quite a
    different part of the heavens from that in which the aëroplane was
    seen.

The vertical range of aircraft artillery is much higher. In the case
of a one-pounder having the same velocity the range would be over
12,000 feet; but it is a question of luck whether the aëroplane would
be hit. The great difficulty is the angle of “lead” which must be given
to allow for the velocity of flight.

    This angle is only constant so long as the velocity of the
    projectile is constant, assuming (as fairly represents the
    conditions) the flight speed not to vary; at extreme heights the
    velocity of the projectile has fallen so low that a very slight
    error in range-finding will be fatal to accuracy.

In regard to aëroplane artillery, Mr. W. F. Reid has collected some
interesting details of the guns that Krupp has devised for the purpose
of hitting aëroplanes.

    The 7.5 cm. gun of this firm has seats for five men and storage for
    sixty-two shells. It is mounted on a car which weighs 4,300 kilos.,
    the weight of the gun alone being 1,065 kilos. Each projectile
    weighs 5.5 kilos. (12 lb. 2 oz.), and the horizontal range is given
    as 9 km. The vertical range is 6,300 metres.

    A lighter gun of 6.5 cm. gauge weighs, with car, 875 kilos., the
    gun weighing 352 kilos. Each projectile weighs 4 kilos. (8 lb. 13
    oz.), and the extreme horizontal range is stated to be 8,650 metres
    (9,450 yards). The height of fire obtainable is 5,700 metres
    (18,700 feet). The initial velocity of the projectile is 620 metres
    (2,034 feet) per second. A coiled spring balances the weight of the
    gun when pointed above the horizontal.

    For naval purposes Krupp has constructed a 10.5 cm. gun weighing
    3,000 kilos, with carriage. The projectile weighs 18 kilos. (40
    lb.). The muzzle velocity is 2,100 feet per second, and the shells
    discharge a train of smoke to facilitate aiming.

    Ehrhardt, in Düsseldorf, has also built a special gun for use
    against aërial craft. Its bore is 5 cm., and its barrel is 30
    calibres long, while the length of the Krupp barrels is 35
    calibres. The weight of the Ehrhardt gun alone is 400 kilos.; with
    car, ammunition, and five men the weight is 3,200 kilos.

With regard to the difficult subject of armouring aëroplanes, I should
like again to quote from Mr. Lanchester:--

    It is manifestly not possible for an aëroplane to perform all
    the duties required of it in connection with tactical operations
    at high altitude[B], and whenever it descends below 5,000 feet
    or thereabouts, it is liable to attack from beneath; in fact, at
    such moderate altitudes it must be considered as being under
    fire--mainly from machine-gun and rifle--the whole time it is
    over or within range of the enemy’s lines. Protection from the
    rifle bullet may be obtained in either of two ways: the most vital
    portions of the machine, including the motor, the pilot, and
    gunner, can only be effectively protected by armour-plate; the
    remainder of the machine, including the wing members, the tail
    members, and portions of the fuselage not protected by armour, also
    the controls, struts, and the propeller, can be so constructed
    as to be _transparent_ to rifle fire--that is to say, all these
    parts should be so designed that bullets will pass through without
    doing more than local injury and without serious effect on the
    strength or flying power of the machine as a whole; in certain
    cases components will require to be duplicated in order to realise
    this intention. It is important to understand clearly that any
    intermediate course is fatal. Either the bullet must be definitely
    resisted and stopped, or it must be let through with the least
    possible resistance; it is for the designer to decide in respect
    of each component which policy he will adopt. The thickness of the
    armour required will depend very much upon the minimum altitude at
    which, in the presence of the enemy, it is desired to fly; also
    upon the particular type of rifle and ammunition brought to bear.
    There is a great deal of difference in penetrative power, for
    example, between the round-nosed and pointed bullets used in an
    otherwise identical cartridge.

      [B] For military purposes we may take the term “high
          altitude” as defined by the effective vertical range of
          small-arm fire, in other words, as denoting an altitude
          of 5,000 feet or 6,000 feet or more.

    If it were not for the consideration of the weight of armour, there
    is no doubt that an altitude of about 1,000 feet would be found
    very well suited for most of the ordinary tactical duties of the
    aëroplane. At such an altitude, however, the thickness of steel
    plate necessary becomes too serious an item for the present-day
    machine, even allowing for the very excellent and highly efficient
    bullet-proof-treated steel that is now available; at the altitude
    in question, the minimum thickness that will stop a 0.303 Mark
    VI. round-nosed bullet is 3 mm. (⅛ in.), but, if attacked by the
    modern pointed-nose Mauser, nothing short of 5 mm. or 6 mm. is of
    avail. If we compromise somewhat in the matter of altitude and
    prescribe 2,000 feet as the minimum height for which protection
    is to be given, the figures become 2 mm. (about 145 W. gauge) for
    the 0.303 round-nosed bullet, and for the pointed Mauser 3 mm. or
    slightly over; at present it is not expected that it will pay to
    armour a machine for the duties in question more heavily; thus we
    may take 2,000 feet as representing the lower altitude limit of
    ordinary military flying.... On this question of armour it cannot
    be too strongly insisted upon that anything less than the necessary
    thickness definitely to stop the projectile is worse than useless;
    a “mushroomed” bullet, possibly accompanied by a few detached
    fragments of steel, is infinitely more disagreeable and dangerous
    than a bullet that has not been upset.

    An aëroplane armoured in all its vitals with 3 mm. steel, and
    otherwise designed on the lines indicated, flying at not less than
    2,000 feet altitude, will be extremely difficult to bring down; so
    much so, that unless its exposed structural members be literally
    riddled and shattered by rifle and machine-gun, or unless a gun of
    larger calibre be brought to bear, it will be virtually impossible
    to effect its capture by gun-fire alone.


4. _Rapid despatch carrying to a distance._

Considering the advantages of the swift monoplane for carrying
despatches from one commander to another, it would seem that in time it
must oust the despatch rider.

There is no obstacle to the despatch rider. The difficulties and delays
of hills, woods, and rivers melt away before his ever onward course.
The despatch rider on horseback may have to face the sudden appearance
of the enemy, but if the aëroplane despatch carrier does, he has only
to rise up out of his range of fire, and, still undisturbed, he can
make his way towards his destination. There must surely already be
many instances of the use of the new arm in this way in the present
war. It has been reported that the Germans used aëroplanes to send
messages to recall German troops stationed in the village of Coutrai to
reinforce those at Charleroi.


5. _Distributing handbills to cities._

This is a use which has not been much taken into account until the
present war. It appears, however, one that is destined to become very
general in war. It has been already used either to excite terror or
encouragement amongst the population of a city either already besieged
or threatened with speedy investment. It has been stated that when
Liége was besieged the French aviators distributed circulars over the
city to the effect that the citizens should keep up their courage, as
help would soon be forthcoming. When the Germans were approaching Paris
the German aviators distributed pamphlets urging the surrender of the
Parisian capital. Reports also came to hand that French aviators flew
over Alsace and Lorraine with pamphlets to describe the violation by
Germany of the neutrality of Belgium and Luxemburg!


6. _Photography._

The value of aëroplanes for this work in war is self-evident, and
various means for securing good photographs from flying machines
have been devised. Some years ago the public was made familiar with
photographs at great altitudes in the air by the beautiful specimens
taken by the late Rev. J. Bacon and the late Mr. Percival Spencer
from the cars of their balloons. Since then Mr. G. Brewer has become
an adept in the art of aërial photography. The clearness of detail in
these photographs gives sufficient evidence as to the value of aërial
photography in war.

Satisfactory photographs from balloons have been taken from as great
a height as 10,000 feet. The success of aërial photography, however,
depends upon the amount of haze upon the earth, which veils the plate
from the actinic power of the reflected light. In taking aërial
photographs from aëroplanes, owing to meteorological conditions it may
often be necessary in war to take the photographs from lower and more
perilous positions. The value of the photographs will, however, often
be worth the risk, as very complete aërial surveys of war regions can
be made from a series of photographs.

For taking photographs from aëroplanes special and in some cases
automatic cameras have been designed.

The Germans use a camera fitted with a special Telephoto lens.

In an apparatus of British make, designed by Mr. Baker, the camera is
suspended beneath the aëroplane. The airman presses one button to make
an exposure, another when he wishes to change the plate.


7. _Locating submarines, mines, etc._

In the present war ample evidence has been given of the deadly work
that submarines, torpedoes, and mines can perform. Some years ago the
late Rev. J. Bacon carried out experiments from balloons to show that
when the surface of the sea is viewed from an altitude the observer
has a vision which penetrates to some depth below the surface. At the
time the great advantage of such surveys in naval war-time was pointed
out.

Such aërial surveys form an important use for both the smaller types
of airships, aëroplanes, and hydroplanes. When more records come to
hand than it is now possible to obtain in regard to naval doings in the
present war it will be interesting to observe the amount of actual work
that has been done in detecting submarines and the other hidden dangers
in the sea.




CHAPTER XI

PRESENT DEFICIENCIES AND FUTURE POSSIBILITIES OF THE MILITARY AËROPLANE


In the portion of this handbook which especially dealt with airships,
certain advantages possessed by them over aëroplanes were noted;
several of their disadvantages were also a matter of comment. It
was hinted that in the future it might be possible to impart to
aëroplanes also those very advantages of which the airship can still
certainly make boast. Should this be done by engineering skill--and
it is well within the limits of reasonable possibility--then it would
seem that the lighter-than-air machine must entirely yield its claim
as an adjunct of war to the heavier-than-air principle. The free
balloon “mounting heavenwards,” as Carlyle said, “so beautifully,
so unguidably,” is now merely a past reminiscence, and even so, too,
will be the mammoth motor-impelled gas envelopes. When the din of war
ceases, the still greater perfection of the aëroplane should be the
object of the attention of British engineering skill. The endowment of
the aëroplane with certain qualities in which it is still deficient
appears to be merely a matter of engineering detail based on principles
that have been already elucidated.

Since the brothers Wright made their epoch motor flights which gave to
man the attribute of the bird, so long his envy, progress in flight
records has been largely made in the attempt to win a money prize.
In one sense the pilot has progressed at a faster rate than has the
evolution of the machine. He has accomplished heights, durations, and
distances on machines in which the margin of safety is indeed small.
It might be well if the next series of prizes should be devoted to the
further development of the machine itself--prizes which would, in their
turn, stimulate the genius of the aëronautical engineer.

Four essential points in the future development of flying machines
are:--

  1. Variable speed.

  2. Immediate rising into the air.

  3. Hovering in the air.

  4. Stability.


1. _Variable speed._

The aërial machine that cannot vary its speed, so as to be able to go
fast, at moderate pace, or quite slow, must from one point of view be
in a crude state of development. Yet aëroplanes are as yet in this
stage of growth.

More than one plan has been suggested for endowing the aëroplane with
the power of variable speed, which would make its use in war still
greater. One of these plans is the extension and reducing at will of
the sustaining surfaces, so that for high speeds the practical minimum
of surface may be utilised, for low speeds the practical maximum. A
machine to produce this result has been already planned by Mr. C. F.
Webb. It was described at a meeting of the Aëronautical Society of
Great Britain in 1906. At the time of the reading of the paper the
world was hardly ready to realise the importance of considering this
problem; at the present moment all military aëronautical experts agree
as to the advisability of the production of a variable speed flying
machine, though they shirk the complexity of structure the variable
speed machine would seem to necessitate. In Mr. Webb’s design is a
form of aëro-surface which, by special adaptation, can vary its area
in accordance with the requirements of, and in proportion to, the
constants, speed, and weight, and thus automatically adapt itself to
the requirements of the varying speed of the wind. In this machine the
two wings are situated on each side of the car in such a way that the
centre of support of each is some distance above the centre of the
mass of the machine. Each wing is fan-curved from front to rear, with
the outermost segment longer than the innermost. The fan wings are
opened or contracted by a hand-lever arrangement, and besides the hand
levers there is an automatic pendulum mechanism which regulates their
area to the requirements of the wind. Whether or no the inventor’s
exact arrangements may prove on trial to be successful is a matter on
which decisive opinion cannot be given; but the principle of expanding
and diminishing surface is thoroughly sound, and is worthy of lavish
expenditure and experiment. Other ways of attaining variable speed
machines have been suggested, though the method of a variable surface
would seem likely to carry the regulation of speed to a greater nicety
than do the other plans. One of these projects is to alter the angle
of the incidence of the planes while the machine is in flight; the
angle would have to be steep for slow speed, and gradually flatten for
increase of speed.


2. _Immediate rising into the air._

It is undoubtedly a disadvantage of the aëroplane that it has to run on
the ground on wheels to get the initial velocity necessary for flight.
In some of the earlier military experiments with aëroplanes the
machines were made to run over ploughed fields, for it was recognised
that machines which could only rise when running on smooth ground would
be useless for military work. But one can imagine that it may often
be expedient in military operations for machines to rise from land so
unequal that with the present method flight would be impossible.

The perfect military aëroplane should be able to rise in the air at any
time and from any place. The application of horizontal lifting screws
beneath the flying machine would make this a possibility, though it
would be necessary to have two of such screws revolving in opposite
directions. It is indeed curious that so little has been done in the
way of such experiments. It will be said that each added screw means
engine multiplication and complication; but these difficulties are
details of engineering that are not unsolvable.

In the case of such large aëroplanes as the Russian type that has been
described, it would seem specially feasible to attach the lifting
screws.


3. _Hovering in the air._

One great advantage of the lifting screws would be that by their use
the machines could hover in the air. Now, when the vertical screw
is stopped, the aëroplane must fall to earth unless the aviator
makes the “vol-plané.” This necessity brings into strong relief the
present imperfection of the flying machine. When horizontal screws
are attached to a flying machine we really have the essential feature
of sustentation, and the existence of the ordinary supporting surface
becomes superfluous. The flying machine has, in fact, become of the
“Hélicoptère” type, though doubtless for some time the supporting
surface will be retained as a means of additional security; in time it
may vanish altogether, and support as well as progression depend upon
revolving screws.


4. _Stability._

It has been stated that the properly constructed airship is stable
when in the air; it has not got to fear the more treacherous side gust
which over and over again has brought the aëroplane to earth, and
coupled its name with tragedy. The vexed problem of the stability and
equilibrium of aëroplanes is the most important that has yet to be
solved; until this is done it is not likely the airship will completely
disappear as an instrument of war. In speaking of the remarkable
exploits of Pégoud, it was said that they were an object-lesson on
the materiality of the air, and we have yet to learn how to use this
materiality to the best advantage, so as to afford us continual
stability. Until the problem is solved, man cannot be said to have
brought himself to the level of the soaring bird; the latter, indeed,
makes good use of the very attributes of the wind which at present
tend to upset the aëroplanist--the vertical component of the wind,
its internal work, _i.e._, its gustiness; its non-uniformity, _i.e._,
its different velocities at different levels. Every light, therefore,
that can be thrown experimentally or mathematically on the difficult
subject of equilibrium and stability should be eagerly sought.

Professor G. H. Bryan’s mathematical researches are indeed
epoch-making, and their study by the aëronautical engineer should be
prolific of practical result. He does much to elucidate points of
the problem of stability that before had been imperfectly grasped.
For instance, take the case of his remarks as to distinction between
equilibrium and stability.

    We say that the motion of a flying machine is steady when the
    resultant velocity is constant in direction and magnitude, and when
    the angle of the machine to the horizontal is constant. If this
    motion is slightly disturbed the machine may either return after a
    time to the original motion, or it may take up a new and altogether
    different mode of motion. In the first case, the steady motion is
    said to be stable, and in the second unstable.

    It is evidently necessary for steady motion of any kind that there
    should be equilibrium--_i.e._, that there should be no forces
    acting on the machine (apart from accidental disturbances) which
    tend to vary the motion, and hence it follows that the number
    of modes of steady motion of which a machine is capable is, in
    general, limited, and that when an unstable, steady motion is
    disturbed, the new mode of motion taken up is entirely different
    from the old.

    It is necessary to distinguish carefully between equilibrium and
    stability, as the two are very often confused together. Equilibrium
    is necessary to secure the existence of a mode of steady motion,
    but is not sufficient to ensure the stability of the motion. The
    question of the stability of a rigid body moving under the action
    of any forces has been solved by Routh. In order to apply his
    results to the stability of flying machines, it is necessary to
    know the moment of inertia of the machine about its centre of
    gravity, the resistance of the air on the supporting surfaces as a
    function of the velocity and angle of incidence, and also the point
    of application of this force--_i.e._, the centre of pressure for
    different angles of incidence. If these are known for the surfaces
    constituting any machine, then the problem of its stability for
    small oscillations can be completely solved. Unfortunately, our
    knowledge of these points is very unsatisfactory. Several valuable
    series of experiments have been made to determine the resistance
    on planes, but there is still some doubt as to the position of the
    centre of pressure at small angles of incidence, especially for
    oblong planes, and very little indeed is known as to the movement
    of the centre of pressure on concave surfaces. Until experiments
    are made on this point it will be impossible to solve the problem
    of stability for machines supported on concave surfaces.

The subject of the stability of aëroplanes falls under two heads:--

1. Automatic stability.

2. Inherent stability.

Attempts have been made to produce the first by the aid of moving
gyroscopes and pendulums without much success, and Professor Bryan has
pointed out, apart from the fact that movable parts are likely to get
out of order, they also increase the degree of the friction of the
machine, thus further adding to the number of conditions that have to
be satisfied for stability.

It would seem, therefore, that the desideratum is inherent stability.
Professor Bryan considers that there is hope of attaining longitudinal
and lateral stability by the use of exhaustive mathematical researches;
these will result in the fixing of independent auxiliary surfaces
in aëroplanes in such happy positions as will secure stability in
all conditions of atmosphere. Or it may well be that through some
unlooked-for observation or simple experiment the answer will come. In
the shape of the aëroplane surfaces alone may be the solution of the
problem. But if the aëroplane be still an imperfect instrument, it is
sufficiently developed to be already one of the greatest factors of
modern warfare.


_Printed by Hazell, Watson & Viney, Ld., London and Aylesbury._--1414573




Transcriber’s Notes


Punctuation, hyphenation, and spelling were made consistent when a
predominant preference was found in the original book; otherwise they
were not changed.

Simple typographical errors were corrected; unbalanced quotation
marks were remedied when the change was obvious, and otherwise left
unbalanced.

Illustrations in this eBook have been positioned between paragraphs
and outside quotations. In versions of this eBook that support
hyperlinks, the page references in the List of Illustrations lead to
the corresponding illustrations.

Page 2: “the battle of Fleurus, 1794” was misprinted as “the battle of
Fleurus, 1784”.

Page 86: “the longest being 22½ feet” was printed that way.