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CH.VI AIRSHIP VERSUS AEROPLANE 83

lines, or where existing lines had been destroyed.
There are, in fact, quite a number of ways in
which their services would be valuable, but such
purposes would all be of minor importance, and
subservient to the real uses which make aircraft
so invaluable in war.

In justice to airships, their early state
of development must be remarked upon. As
there have been thousands of aeroplanes con-*
structed as against about a hundred airships,
the former are naturally in a far more advanced
stage of evolution. It is, therefore, premature
to lay down a final judgment as to their value
for military purposes, for in the next great war
dirigibles may be capable of doing all manner of
things which appear utterly impossible for craft
of their class to-day.

We can, therefore, only specify their limita-
tions in the present campaign. That these
limitations are very narrow, and, indeed, in-
finitely out of all proportion to the utility of the
airship, is apparent. More than once since war
broke out the Zeppelin has been likened to a
battleship of the air, and the aeroplane to a sub-
marine or destroyer. But this parallel is all in
error, for the only similarity is that an ironclad,



84 AIRCRAFT

if unprotected by destroyers, is, like a Zeppelin,
more or less at the mercy of its small antagonist.
On the other hand, the battleship has enormous
and unequalled power for most operations of
naval warfare, and is supreme against all other
seacraft, while the submarine possesses no other
function but the one. A Zeppelin not only cannot
compete with the aeroplane as regards travelling
*power, but, moreover, it cannot perform most of
the military functions for which heavier-than-air
craft are employed.

The Zeppelins appear somehow to have
assumed, among the general public, terrifying
proportions ; their actual dimensions are, perhaps,
alarmingly big indeed, they certainly are. But
as engines of war they are lamentably defective
machines ; and it is only necessary to examine
closely their capabilities to discover how nearly
destitute they are of merit for military use.



CHAPTER VII

TYPES OF AIRCRAFT IN USE



IN the preceding chapter, when writing of air-
ships, reference was generally made specifically
to Zeppelins. This was done for two reasons ;
first, because it is against airships of the Zeppelin
type that we have chiefly to contend in the
present War; secondly, because they are the
finest and most efficient dirigibles yet produced,
and it is only fair to name the best examples
of a class of aircraft as representative of what
the whole is capable.

There are, however, various other kinds of
airships in use both in Germany and in other
countries. In Germany there are four chief
types. First, of course, there is the Zeppelin,
the distinctive feature of which is the rigid
framework, composed extensively of aluminium,
over which the envelope is stretched. Secondly,

85



86 AIRCRAFT PT.I

there is the Schiitte-Lanz, nearly equal in size
to the Zeppelin, also a rigid type of vessel,
but with the frame constructed chiefly of three-
ply wood instead of metal. This ship has a
pointed tail, unlike the blunt end of a Zeppelin,
which makes it rather the faster of the two. It
appears that some of the latest Zeppelins are
having their tails built in a pointed shape to
increase their speed. Thirdly, there are the
semi-rigid airships built by the German Govern-
ment, which are supple all round except at the
keel, along which iron girders are fixed the
whole length, and from which the cars are
suspended. The fourth type is the Parseval,
a rather smaller vessel, which is entirely supple,
with no rigid construction in the envelope at
all. Nearly all airships belong to one of these
four types.

| Germany is certainly far ahead of any other
nation as regards airships, both in knowledge
and in actual possession. France has a fairly
large fleet of dirigibles, chiefly of the Astra,
Clement-Bayard, Zodiac, and Lebaudy types;
Italy has about a dozen small but useful ships ;
and then (when war broke out) came Great
Britain with a few of the miniature ships of the



CH.VH TYPES OF AIRCRAFT IN USE 87

" Beta " type, a Parseval, and an Astra-Torres
one of the fastest ships ever built. These
originally belonged to the Army, but were later
taken over by the Navy. In the particular
spheres of utility to which all airships are limited,
they have done some good work during the War,
but compared to Zeppelins they resemble toys.

There is one function in military aeronautics
where lighter-than-air craft have proved in some
ways superior to aeroplanes in their imperfect
present-day state. This has been in directing
artillery fire. Three or four hours is quite a
short duration for one bombardment, and it is a
great strain on an aeroplane pilot to keep aloft
even for that period, especially when he has to
hover as slowly as possible round one position,
while he is subjected to a severe gunfire from the
enemy. The Germans some time ago brought
out the Parseval-Sigsfeld kite-balloon, which is a
small sausage-shaped balloon, anchored generally
to a motor-driven winch on the ground. Along
the bottom of the ballonnet is what looks in the
air like an additional bulge, which holds it
excellently against the wind. These balloons
carry from one to three observers, according to
their size, and their superiority to the ordinary



88 AIRCRAFT

man-lifting kite is, of course, that they do not
require a wind to lift them from the ground. It
was seen that these contrivances were excellent
for directing artillery fire, as they could stay up
for hours on end with ease, and, accordingly, the
Allies have sensibly made use of the idea. But
although these kite-balloons may be suitable
in some instances, there are many occasions for
which they are totally unsuited, such as when
one observer has to fly about and direct the
gunfire of several batteries. They are, of course,
very vulnerable, so can hardly be used except
near their own lines, and even then they must
be well protected by anti-aircraft guns ; they
cannot, obviously, be used for observing long-
range fire. Aeroplanes, therefore, continue to be
used for directing gunfire far more extensively
than these kite-balloons.

This particular comparison, like many others,
shows the desirability of fitting aeroplanes with
more than one engine, and with dual control, and
so enabling them to keep aloft for longer periods
with ease. It is an unnecessary drawback that
aeroplanes should only have a single engine,
for it is a drawback which can be overcome.
Also many pilots, when their engines have been




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CH. vii TYPES OF AIRCRAFT IN USE 89

stopped by a mechanical defect or by a bullet,
would have been saved from death and their
machines from falling into the hands of the enemy
if they had had even a partial reserve of engine
power to fall back upon; and numberless machines
would have been saved by observers when the
pilot had been shot, if dual control had been fitted.

For the merit of the multiple -engined aero-
plane in warfare is essentially, not so much
that it shall be provided with greater aggregate
power, as that it shall be far more reliable, by
being able to fly reasonably well with but a
proportion of its motors running, should the
remainder have been put out of gear.

There have been many attempts made in
this direction ; in England, years ago, by Short
Bros., and more recently by other constructors
in America and Russia. But the first successful
application of the principle during the War
apart from Sikorsky was the biplane fitted
with two 80 h.p. engines, each revolving a
separate propeller, made by the Caudron firm
in France. This was followed by the German
battle-aeroplane, which was an improvement of
the same idea. This battle-aeroplane he is
called " Fritz" -is extremely fast and very



90 AIRCRAFT FT. i

reliable, and at the time of appearance was
the best machine of the type that had been
produced.

Both the German machine and the Caudron
are aeroplanes which, though fitted with multiple
engines, are only incidentally larger than usual ;
in fact, in the latter the size is increased as little
as possible to accommodate the additional power
plant. This should be specially noted by those
who are under the impression that several
engines serve primarily as an end to the pro-
duction of altogether larger aeroplanes.

However, this increase of size actually is the
principal object in the Sikorsky biplanes, which
are designed chiefly to carry a large crew and
considerable weight.

The Sikorsky is a huge biplane fitted with
four 120 h.p. engines, which are placed at
almost equal distances along the front edge of
the wings. Each engine drives its own pro-
peller, and the aeroplane will fly quite well with
only two of them running. In the position
where the nacelle and engine are placed in an
ordinary machine, a totally enclosed cabin for
the crew is built. The Sikorsky can take sixteen
passengers quite easily, and has on occasions



CH. vn TYPES OF AIRCRAFT IN USE 91

ascended with well over twenty persons on
board.

Considered purely as a flying machine, aero-
planes of this type i.e. those in which weight-
carrying is the first consideration are quite
efficient ; but as serviceable war aeroplanes
their relatively slow speed and climbing power
detract from their value considerably. It would
seem that the most advantageous solution for
the present War is a compromise between size,
or rather weight-carrying capacity, the two
are synonymous in an aeroplane and the best
possible speed and climbing power consonant
with effectiveness. In other words, multi-
engined aeroplanes for the War should be large
and powerful enough to be able to carry a good
many more bombs than ordinary machines, and
yet still sacrifice enough of weight - carrying
capacity for sufficiently fast speed and climb to
make them really useful.

It can be seen that with the development of
the multi-engined machine, not only will the
aeroplane more nearly approach the airship as
regards weight-carrying, but it will also compete
with it in regard to duration. For the multi-
engine principle will greatly increase the re-



92 AIRCRAFT

liability of aeroplanes and go far to relieve the
pilot of the mental anxiety which he often feels
in war time when his engine is troublesome ;
while even a small consequent increase in the
size of aeroplanes will make it possible to carry
several pilots, who could take it in turns to
control the machine. So the great strain which
staying aloft for several hours at present im-
poses on pilots would be considerably lessened.

The task of flying in war time will also be
made far easier with the perfection of auto-
matically stable aeroplanes i.e. machines which
will maintain their balance without the assist-
ance of the pilot. At present there is quite a
graduated scale of machines possessing a greater
or lesser amount of inherent stability, from the
very fast scouts, in which the pilot dare not
remove his hands from the control lever for a
second, to the machines specially designed for
inherent stability, such as the Dunne 1 biplane,
on which the aviator can walk along the wings
in mid-air without having to worry in the least
about the machine not flying safely. In addi-

1 It should be stated that the Dunne biplane is a machine of
completely different type from any other aeroplane. The wings form
a V, and there is no fuselage. However, although the Dunne is the
most stable machine existing, there are many other aeroplanes of
ordinary type which are also very stable.





By courtesy of " Flight."



TWO VIEWS OF AN ETRICH MONOPLANE.

This is a typical example of the aeroplanes with swept-back wings which German constructors
used to build before the war. They were extremely stable, but had to be abandoned owing to
t.hp.ir vfilativfilv slow snfied.



CH. vn TYPES OF AIRCRAFT IN USE 93

tion to this particular aeroplane, there are many
others which will fly perfectly well without the
pilot touching the controls for long periods.

Automatic stability received more encourage-
ment in Germany than anywhere else, and for
years the predominating feature of nearly all
German machines was their swept-back wings,
which made them more stable than other aero-
planes. Wings of this shape were abandoned
in order to obtain greater speed and climbing
power, for indeed it has been found that
really stable aeroplanes are generally slow, and
therefore cannot be employed extensively in
war. The present campaign has shown that
completely automatic stability would be such
an enormous asset in war that constructors will
certainly experiment further in this direction
in order to endeavour to produce, if possible,
very fast machines that are inherently stable.
At present it would seem that biplanes generally
lack speed in proportion to their stability. But
from that it must not be imagined that slow
machines are necessarily stable, for this is cer-
tainly not the case.

In regard to aeroplanes increasing their
lifting capacity, vast new possibilities can be



94 AIKCRAFT

seen, some of which may reach fulfilment before
the end of the War. Some one has pointed out
that it is not necessarily an advantage at all for
machines to be able to carry more bombs than
they can at present, as that would mean " trust-
ing too many eggs to one basket." If this argu-
ment is set out on the hypothesis that where
forty small aeroplanes now perform a raid, half a
dozen larger machines carrying the same quantity
of explosives would do the work less effectively,
this view is probably correct ; because, in the
first place, the larger machines would present a
better target for the enemy ; secondly, if, say,
two machines out of forty were brought down,
it would not matter very much, while the loss
of two of the six large ones would make a con-
siderable difference to the raid. But if this is
the basis of the argument, the chief advantage
of having large aeroplanes which is that a far
greater total quantity of bombs can be dropped
immediately vanishes.

As regards the immediate evolution of really
large aeroplanes for use in the present War, a
great deal depends on the engines which we
can make for them. In this direction Germany
certainly has the lead, for she has had for long



CH. vii TYPES OF AIRCRAFT IN USE 95

past a very large output of engines which are
well constructed and very reliable ; whereas at
the beginning of the War there were only one
or two firms in this country constructing aero-
engines of any sort whatsoever. However, our
ally, France, has been of the utmost assistance
to us in the matter of motors, not only in send-
ing us large supplies of actual output, but also
in assisting British engineering firms to com-
mence the manufacture of French engines of
proved merit.

The engine of an aeroplane is indeed its very
life, and with a weak or faltering motor the best
designed machine is wasted. In the early days
of aviation it was the petrol motor that made
flying even possible ; and to-day the aeroplane
is still as dependent on the engine for the con-
tinued development of aviation, as it was in the
darkest ages of flying.

There are, roughly, two distinct types of
aero-engines in use to-day. There is the rotary
type, in which the whole engine revolves,
generally at the same rate as the propeller, and
of which the best examples are the Gnome
and Le Rhone. The great asset of engines of
this type is their extraordinary lightness for



96 AffiCKAFT

power, and it must be remembered that light
weight is an enormous advantage in an aero-
plane, where every pound saved is of the utmost
importance. On the other hand, their great
drawback is the delicate character and sen-
sitiveness of their working. They require a
great deal of attention, and not only must they
constantly be dismantled and cleaned out after
every few hours' running, but they also want
skilful, experienced handling and " tuning up "
to obtain the best results. This is naturally a
serious drawback in warfare.

The other 1 class of engine is the stationary
type, similar in principle to the ordinary motor-
car engine. A good stationary aero-engine
wants very little adjusting and will run for a
long period without attention ; but, although
it is more reliable than most rotaries, it is

heavier,
u

There is, therefore, on the one hand the
powerful, light, but delicate rotary engines,
which have been most successfully produced in

1 Besides these two chief types of engines, there are one or two
aeromotors constructed on the radial principle. In these, the
cylinders are placed in a circle, in the centre of which is the crank-
shaft. ^ The cylinders are fixed and do not revolve. Very good
results are obtained from these engines, which have proved highly
satisfactory.



CH.VII TYPES OF AIRCRAFT IN USE 97

France ; and, on the other hand, the wonder-
fully reliable, but comparatively heavy, station-
ary engines, made by such firms as Mercedes and
Benz in Germany, in Italy by F.I.A.T., and
in England by Beardmore, The Green Engine
Company, and the Sunbeam Company. Two
or three years ago the aeroplane seemed behind
the engine in point of development, but to-day
it has possibly surpassed it. What is now
awaited is the production of a very powerful
engine combining lightness with efficiency and
reliability.

It is most essential for the progress of aviation
that a really big petrol engine should be evolved.
Up to the present, approximately 300 horse-
power is about the utmost for a successful aero-
engine, but this is not nearly powerful enough,
for in the near future petrol engines will be
required developing, not hundreds, but thousands
of horse-power.

That such engines can be evolved there is
little doubt. When Bleriot crossed the Channel
in 1909 the aero -engine he used was a 25
horse-power Anzani ; and in the few years since
then we have increased the power of our

aero -engines tenfold, so that events show a

H



98 AIECEAFT

definite and distinct trend towards the demand
being met for really high-powered aeroplane
engines.

As regards the progress of aircraft in general,
there is one type in particular which it must
inevitably fall to the lot of Great Britain to
develop and perfect. That type is the seaplane.
It is natural, as an island nation possessing a
great Navy, a vast mercantile fleet, and having
interests and responsibilities chiefly on the seas,
that this country should find special interest in
seaplanes. Even to-day we have made greater
progress, and are better equipped with them,
than any other Power.

There are many special difficulties peculiar
to the seaplane. Even if, in specified cases, a
machine may fly and alight as well with floats
attached as with a land chassis, that does not
mean that seaplanes are simply aeroplanes fitted
with floats. Far from it.

There are, of course, various kinds of sea-
planes, ranging from the delicate contrivance
which, if carefully handled, may occasionally
descend safely on very calm water, to the
really big affair that will stand up to a fairly
choppy sea. The most difficult problem about



CH.VH TYPES OF AIKCEAFT IN USE 99

a seaplane is, indeed, to make it seaworthy. In
the future, when very big seaplanes are evolved,
they will have to be able to withstand much
rougher seas than can the machines which exist
to-day. In fact, they will have to be able to
remain safely anchored in almost as bad weather
as most ships can stand to-day.

The prospect of crossing the Atlantic by
aeroplane will almost certainly be revived after
the War, and there is a clear probability of a
successful crossing by air being made within a
short time after peace is declared.

One of two methods will have to be decided
upon by any one who resumes the attempt.
The first plan is to design a machine without
providing against an involuntary descent, which
in such an aeroplane would undoubtedly prove
fatal. The machine on which the late Mr.
Hamel intended to attempt the cross-Atlantic
flight was of this type, and the great advantage
gained is in lightness. The second plan is to
endeavour to construct a seaplane capable of
making an enforced and, if necessary, prolonged
descent in safety. At present no existing sea-
plane could stand up to ordinary Atlantic
breakers for five minutes ; and the problem of



100 AIKCKAFT

making a seaplane capable of doing so will
prove a very difficult one.

People who do not realise the extraordinary
driving force of the sea should witness a sea-
plane, which on land appears very strong, being
turned over and smashed like matchwood by
the breakers of a comparatively light sea. The
simple remedy of indefinitely increasing the
constructional strength of the seaplane is not
wholly practical, for the obvious reason that if
a seaplane is made too heavy it will not ascend
from the water easily, or fly properly ; and,
after all, the seaplane's element is the air and
not the water, even if it does have to rest on
the latter frequently for quite long periods. Be-
sides, resisting the waves is not only a matter of
material strength, because once a seaplane over-
turns it will sink, and the strongest seaplane
might overturn more easily than a lighter one
better designed to sit on rough water. The
really successful seaplane must be seaworthy as
a result of its design rather than of its actual
material strength, just as the best specimens
lift off the water easily because of the good
design of their floats, instead of by sheer engine
power alone.



on. vii TYPES OF AIBCE AFT IN USE 101

As a matter of fact, this " getting off'" with
seaplanes for long presented a difficult technical
problem to seaplane constructors. The suction
of the water to ordinary flat-bottomed floats is
enormous, and until recently this suction was
only overcome by engine power simply wrench-
ing the machine off the water. Now, however,
specially designed floats have practically elimi-
nated this obstacle, and seaplanes can " get
off" smoothly and without strain or effort.
But before any measure of success was attained,
floats of the most extraordinary shapes and
designs were produced, for years.

Many people express surprise when they
learn that it is far more difficult to fly a seaplane
than a land -machine. The general impression
seems to be that water is a sort of feather bed
which breaks the fall of a bad landing. The
actual facts, however, are quite different. Not
only has the seaplane pilot to land on a sub-
stance which is quite as unyielding for that
particular purpose as the ground, but, unlike
the solid earth, the portion of that substance
which he has selected for landing on may com-
pletely upset his calculations by rising up
several feet, or descending an equal distance,



102 AIRCRAFT

or doing both within two seconds, just at the
crucial moment when he is flattening out after
his volplane. Many stretches of water are quite
transparent from above, trees or plants growing
on the bottom being clearly visible, and in such
cases it is extremely difficult, when flying, to
judge exactly the level of the surface of the
water, especially when there is a slight mist or
fog. As a safe landing depends essentially on
the pilot being able to judge just when to
straighten the flying angle of his machine, this
is a serious matter.

It is probable that in the future considerable
attention will be paid to the amphibious type
of aeroplane i.e. that which can descend on,
and ascend from, land or water, for there
appear to be great possibilities in this class of
craft, especially in a country like England,
where the sea must be traversed for every
journey to a foreign land. There have been
several fairly successful attempts made to pro-
duce these amphibians, but somehow they have
been neglected.

As regards the two great types of machines,
monoplane and biplane very much the same
conditions apply to seaplanes as to land-machines,



cn.vn TYPES OF AIRCRAFT IN USE 103

and it is certain that for general naval and
military purposes the machine with two planes
or possibly more will retain its predominance
over the monoplane.

In so far as the principal classes of machines
go, such as pusher (with propeller behind the
planes) and tractor (with propeller in front of
planes), the War has not greatly altered the
opinions previously conceived about them. No
improvement has yet superseded the advantage


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Online LibraryWilliam Alexander RobsonAircraft in war and peace → online text (page 5 of 9)