A History of Aeronautics
by Evelyn Charles Vivian · English · Gutenberg #874 · 815,461 chars · public domain (US)
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Title: A History of Aeronautics
Author: Evelyn Charles Vivian
W. Lockwood Marsh
Release date: April 1, 1997 [eBook #874]
Most recently updated: July 26, 2008
Language: English
Other information and formats: www.gutenberg.org/ebooks/874
Credits: Produced by Dianne Bean, and David Widger
*** START OF THE PROJECT GUTENBERG EBOOK A HISTORY OF AERONAUTICS ***
Produced by Dianne Bean
A HISTORY OF AERONAUTICS
by E. Charles Vivian
FOREWORD
Although successful heavier-than-air flight is less than two decades
old, and successful dirigible propulsion antedates it by a very short
period, the mass of experiment and accomplishment renders any one-volume
history of the subject a matter of selection. In addition to the
restrictions imposed by space limits, the material for compilation is
fragmentary, and, in many cases, scattered through periodical and
other publications. Hitherto, there has been no attempt at furnishing a
detailed account of how the aeroplane and the dirigible of to-day came
to being, but each author who has treated the subject has devoted his
attention to some special phase or section. The principal exception to
this rule--Hildebrandt--wrote in 1906, and a good many of his statements
are inaccurate, especially with regard to heavier-than-air experiment.
Such statements as are made in this work are, where possible, given
with acknowledgment to the authorities on which they rest. Further
acknowledgment is due to Lieut.-Col. Lockwood Marsh, not only for the
section on aeroplane development which he has contributed to the work,
but also for his kindly assistance and advice in connection with the
section on aerostation. The author's thanks are also due to the
Royal Aeronautical Society for free access to its valuable library of
aeronautical literature, and to Mr A. Vincent Clarke for permission to
make use of his notes on the development of the aero engine.
In this work is no claim to originality--it has been a matter mainly of
compilation, and some stories, notably those of the Wright Brothers and
of Santos Dumont, are better told in the words of the men themselves
than any third party could tell them. The author claims, however, that
this is the first attempt at recording the facts of development and
stating, as fully as is possible in the compass of a single volume, how
flight and aerostation have evolved. The time for a critical history of
the subject is not yet.
In the matter of illustrations, it has been found very difficult to
secure suitable material. Even the official series of photographs of
aeroplanes in the war period is curiously incomplete' and the methods
of censorship during that period prevented any complete series being
privately collected. Omissions in this respect will probably be remedied
in future editions of the work, as fresh material is constantly being
located.
E.C.V. October, 1920.
CONTENTS
Part I--THE EVOLUTION OF THE AEROPLANE
I. THE PERIOD OF LEGEND
II. EARLY EXPERIMENTS
III. SIR GEORGE CAYLEY--THOMAS WALKER
IV. THE MIDDLE NINETEENTH CENTURY
V. WENHAM, LE BRIS, AND SOME OTHERS
VI. THE AGE OF THE GIANTS
VII. LILIENTHAL AND PILCHER
VIII. AMERICAN GLIDING EXPERIMENTS
IX. NOT PROVEN
X. SAMUEL PIERPOINT LANGLEY
XI. THE WRIGHT BROTHERS
XII. THE FIRST YEARS OF CONQUEST
XIII. FIRST FLIERS IN ENGLAND
XIV. RHEIMS, AND AFTER
XV. THE CHANNEL CROSSING
XVI. LONDON TO MANCHESTER
XVII. A SUMMARY--TO 1911
XVIII. A SUMMARY--TO 1914
XIX. THE WAR PERIOD--I
XX. THE WAR PERIOD--II
XXI. RECONSTRUCTION
XXII. 1919-1920
Part II--1903-1920: PROGRESS IN DESIGN
I. THE BEGINNINGS
II. MULTIPLICITY OF IDEAS
III. PROGRESS ON STANDARDISED LINES
IV. THE WAR PERIOD
Part III--AEROSTATICS
I. BEGINNINGS
II. THE FIRST DIRIGIBLES
III. SANTOS-DUMONT
IV. THE MILITARY DIRIGIBLE
V. BRITISH AIRSHIP DESIGN
VI. THE AIRSHIP COMMERCIALLY
VII. KITE BALLOONS
PART IV--ENGINE DEVELOPMENT
I. THE VERTICAL TYPE
II. THE VEE TYPE
III. THE RADIAL TYPE
IV. THE ROTARY TYPE
V. THE HORIZONTALLY-OPPOSED ENGINE
VI. THE TWO-STROKE CYCLE ENGINE
VII. ENGINES OF THE WAR PERIOD
APPENDICES
PART I. THE EVOLUTION OF THE AEROPLANE
I. THE PERIOD OF LEGEND
The blending of fact and fancy which men call legend reached its fullest
and richest expression in the golden age of Greece, and thus it is to
Greek mythology that one must turn for the best form of any legend which
foreshadows history. Yet the prevalence of legends regarding flight,
existing in the records of practically every race, shows that this form
of transit was a dream of many peoples--man always wanted to fly, and
imagined means of flight.
In this age of steel, a very great part of the inventive genius of man
has gone into devices intended to facilitate transport, both of men and
goods, and the growth of civilisation is in reality the facilitation of
transit, improvement of the means of communication. He was a genius who
first hoisted a sail on a boat and saved the labour of rowing; equally,
he who first harnessed ox or dog or horse to a wheeled vehicle was a
genius--and these looked up, as men have looked up from the earliest
days of all, seeing that the birds had solved the problem of transit far
more completely than themselves. So it must have appeared, and there
is no age in history in which some dreamers have not dreamed of the
conquest of the air; if the caveman had left records, these would
without doubt have showed that he, too, dreamed this dream. His main
aim, probably, was self-preservation; when the dinosaur looked round the
corner, the prehistoric bird got out of the way in his usual manner,
and prehistoric man, such of him as succeeded in getting out of the way
after his fashion--naturally envied the bird, and concluded that as lord
of creation in a doubtful sort of way he ought to have equal
facilities. He may have tried, like Simon the Magician, and other early
experimenters, to improvise those facilities; assuming that he did,
there is the groundwork of much of the older legend with regard to men
who flew, since, when history began, legends would be fashioned out
of attempts and even the desire to fly, these being compounded of some
small ingredient of truth and much exaggeration and addition.
In a study of the first beginnings of the art, it is worth while to
mention even the earliest of the legends and traditions, for they show
the trend of men's minds and the constancy of this dream that has become
reality in the twentieth century. In one of the oldest records of the
world, the Indian classic Mahabarata, it is stated that 'Krishna's
enemies sought the aid of the demons, who built an aerial chariot with
sides of iron and clad with wings. The chariot was driven through the
sky till it stood over Dwarakha, where Krishna's followers dwelt,
and from there it hurled down upon the city missiles that destroyed
everything on which they fell.' Here is pure fable, not legend, but
still a curious forecast of twentieth century bombs from a rigid
dirigible. It is to be noted in this case, as in many, that the power to
fly was an attribute of evil, not of good--it was the demons who built
the chariot, even as at Friedrichshavn. Mediaeval legend in nearly
every case, attributes flight to the aid of evil powers, and incites
well-disposed people to stick to the solid earth--though, curiously
enough, the pioneers of medieval times were very largely of priestly
type, as witness the monk of Malmesbury.
The legends of the dawn of history, however, distribute the power of
flight with less of prejudice. Egyptian sculpture gives the figure
of winged men; the British Museum has made the winged Assyrian bulls
familiar to many, and both the cuneiform records of Assyria and the
hieroglyphs of Egypt record flights that in reality were never made.
The desire fathered the story then, and until Clement Ader either hopped
with his Avion, as is persisted by his critics, or flew, as is claimed
by his friends.
While the origin of many legends is questionable, that of others is
easy enough to trace, though not to prove. Among the credulous the
significance of the name of a people of Asia Minor, the Capnobates,
'those who travel by smoke,' gave rise to the assertion that Montgolfier
was not first in the field--or rather in the air--since surely this
people must have been responsible for the first hot-air balloons. Far
less questionable is the legend of Icarus, for here it is possible
to trace a foundation of fact in the story. Such a tribe as Daedalus
governed could have had hardly any knowledge of the rudiments of
science, and even their ruler, seeing how easy it is for birds to
sustain themselves in the air, might be excused for believing that he,
if he fashioned wings for himself, could use them. In that belief, let
it be assumed, Daedalus made his wings; the boy, Icarus, learning that
his father had determined on an attempt at flight secured the wings and
fastened them to his own shoulders. A cliff seemed the likeliest place
for a 'take-off,' and Icarus leaped from the cliff edge only to find
that the possession of wings was not enough to assure flight to a human
being. The sea that to this day bears his name witnesses that he made
the attempt and perished by it.
In this is assumed the bald story, from which might grow the legend of a
wise king who ruled a peaceful people--'judged, sitting in the sun,' as
Browning has it, and fashioned for himself wings with which he flew over
the sea and where he would, until the prince, Icarus, desired to emulate
him. Icarus, fastening the wings to his shoulders with wax, was so
imprudent as to fly too near the sun, when the wax melted and he fell,
to lie mourned of water-nymphs on the shores of waters thenceforth
Icarian. Between what we have assumed to be the base of fact, and the
legend which has been invested with such poetic grace in Greek story,
there is no more than a century or so of re-telling might give to any
event among a people so simple and yet so given to imagery.
We may set aside as pure fable the stories of the winged horse of
Perseus, and the flights of Hermes as messenger of the gods. With them
may be placed the story of Empedocles, who failed to take Etna seriously
enough, and found himself caught by an eruption while within the crater,
so that, flying to safety in some hurry, he left behind but one sandal
to attest that he had sought refuge in space--in all probability, if
he escaped at all, he flew, but not in the sense that the aeronaut
understands it. But, bearing in mind the many men who tried to fly
in historic times, the legend of Icarus and Daedalus, in spite of the
impossible form in which it is presented, may rank with the story of the
Saracen of Constantinople, or with that of Simon the Magician. A simple
folk would naturally idealise the man and magnify his exploit, as they
magnified the deeds of some strong man to make the legends of Hercules,
and there, full-grown from a mere legend, is the first record of a
pioneer of flying. Such a theory is not nearly so fantastic as that
which makes the Capnobates, on the strength of their name, the inventors
of hot-air balloons. However it may be, both in story and in picture,
Icarus and his less conspicuous father have inspired the Caucasian mind,
and the world is the richer for them.
Of the unsupported myths--unsupported, that is, by even a shadow of
probability--there is no end. Although Latin legend approaches nearer
to fact than the Greek in some cases, in others it shows a disregard
for possibilities which renders it of far less account. Thus Diodorus of
Sicily relates that one Abaris travelled round the world on an arrow of
gold, and Cassiodorus and Glycas and their like told of mechanical birds
that flew and sang and even laid eggs. More credible is the story
of Aulus Gellius, who in his Attic Nights tells how Archytas, four
centuries prior to the opening of the Christian era, made a wooden
pigeon that actually flew by means of a mechanism of balancing weights
and the breath of a mysterious spirit hidden within it. There may yet
arise one credulous enough to state that the mysterious spirit was
precursor of the internal combustion engine, but, however that may be,
the pigeon of Archytas almost certainly existed, and perhaps it actually
glided or flew for short distances--or else Aulus Gellius was an utter
liar, like Cassiodorus and his fellows. In far later times a certain
John Muller, better known as Regiomontanus, is stated to have made an
artificial eagle which accompanied Charles V. on his entry to and exit
from Nuremberg, flying above the royal procession. But, since Muller
died in 1436 and Charles was born in 1500, Muller may be ruled out from
among the pioneers of mechanical flight, and it may be concluded that
the historian of this event got slightly mixed in his dates.
Thus far, we have but indicated how one may draw from the richest
stores from which the Aryan mind draws inspiration, the Greek and Latin
mythologies and poetic adaptations of history. The existing legends of
flight, however, are not thus to be localised, for with two possible
exceptions they belong to all the world and to every civilisation,
however primitive. The two exceptions are the Aztec and the Chinese;
regarding the first of these, the Spanish conquistadores destroyed such
civilisation as existed in Tenochtitlan so thoroughly that, if legend
of flight was among the Aztec records, it went with the rest; as to the
Chinese, it is more than passing strange that they, who claim to have
known and done everything while the first of history was shaping, even
to antedating the discovery of gunpowder that was not made by Roger
Bacon, have not yet set up a claim to successful handling of a monoplane
some four thousand years ago, or at least to the patrol of the Gulf of
Korea and the Mongolian frontier by a forerunner of the 'blimp.'
The Inca civilisation of Peru yields up a myth akin to that of Icarus,
which tells how the chieftain Ayar Utso grew wings and visited the
sun--it was from the sun, too, that the founders of the Peruvian Inca
dynasty, Manco Capac and his wife Mama Huella Capac, flew to earth near
Lake Titicaca, to make the only successful experiment in pure tyranny
that the world has ever witnessed. Teutonic legend gives forth Wieland
the Smith, who made himself a dress with wings and, clad in it, rose
and descended against the wind and in spite of it. Indian mythology, in
addition to the story of the demons and their rigid dirigible, already
quoted, gives the story of Hanouam, who fitted himself with wings by
means of which he sailed in the air and, according to his desire, landed
in the sacred Lauka. Bladud, the ninth king of Britain, is said to have
crowned his feats of wizardry by making himself wings and attempting
to fly--but the effort cost him a broken neck. Bladud may have been as
mythic as Uther, and again he may have been a very early pioneer. The
Finnish epic, 'Kalevala,' tells how Ilmarinen the Smith 'forged an eagle
of fire,' with 'boat's walls between the wings,' after which he 'sat
down on the bird's back and bones,' and flew.
Pure myths, these, telling how the desire to fly was characteristic of
every age and every people, and how, from time to time, there arose an
experimenter bolder than his fellows, who made some attempt to translate
desire into achievement. And the spirit that animated these pioneers,
in a time when things new were accounted things accursed, for the most
part, has found expression in this present century in the utter daring
and disregard of both danger and pain that stamps the flying man, a type
of humanity differing in spirit from his earthbound fellows as fully as
the soldier differs from the priest.
Throughout mediaeval times, records attest that here and there some man
believed in and attempted flight, and at the same time it is clear that
such were regarded as in league with the powers of evil. There is the
half-legend, half-history of Simon the Magician, who, in the third year
of the reign of Nero announced that he would raise himself in the air,
in order to assert his superiority over St Paul. The legend states that
by the aid of certain demons whom he had prevailed on to assist him, he
actually lifted himself in the air--but St Paul prayed him down again.
He slipped through the claws of the demons and fell headlong on the
Forum at Rome, breaking his neck. The 'demons' may have been some
primitive form of hot-air balloon, or a glider with which the magician
attempted to rise into the wind; more probably, however, Simon
threatened to ascend and made the attempt with apparatus as unsuitable
as Bladud's wings, paying the inevitable penalty. Another version of the
story gives St Peter instead of St Paul as the one whose prayers foiled
Simon--apart from the identity of the apostle, the two accounts are
similar, and both define the attitude of the age toward investigation
and experiment in things untried.
Another and later circumstantial story, with similar evidence of some
fact behind it, is that of the Saracen of Constantinople, who, in the
reign of the Emperor Comnenus--some little time before Norman William
made Saxon Harold swear away his crown on the bones of the saints at
Rouen--attempted to fly round the hippodrome at Constantinople, having
Comnenus among the great throng who gathered to witness the feat.
The Saracen chose for his starting-point a tower in the midst of the
hippodrome, and on the top of the tower he stood, clad in a long white
robe which was stiffened with rods so as to spread and catch the breeze,
waiting for a favourable wind to strike on him. The wind was so long in
coming that the spectators grew impatient. 'Fly, O Saracen!' they
called to him. 'Do not keep us waiting so long while you try the wind!'
Comnenus, who had present with him the Sultan of the Turks, gave it
as his opinion that the experiment was both dangerous and vain, and,
possibly in an attempt to controvert such statement, the Saracen leaned
into the wind and 'rose like a bird 'at the outset. But the record of
Cousin, who tells the story in his Histoire de Constantinople, states
that 'the weight of his body having more power to drag him down than his
artificial wings had to sustain him, he broke his bones, and his evil
plight was such that he did not long survive.'
Obviously, the Saracen was anticipating Lilienthal and his gliders by
some centuries; like Simon, a genuine experimenter--both legends
bear the impress of fact supporting them. Contemporary with him, and
belonging to the history rather than the legends of flight, was Oliver,
the monk of Malmesbury, who in the year 1065 made himself wings after
the pattern of those supposed to have been used by Daedalus, attaching
them to his hands and feet and attempting to fly with them. Twysden, in
his Historiae Anglicanae Scriptores X, sets forth the story of Oliver,
who chose a high tower as his starting-point, and launched himself in
the air. As a matter of course, he fell, permanently injuring himself,
and died some time later.
After these, a gap of centuries, filled in by impossible stories of
magical flight by witches, wizards, and the like--imagination was
fertile in the dark ages, but the ban of the church was on all attempt
at scientific development, especially in such a matter as the conquest
of the air. Yet there were observers of nature who argued that since
birds could raise themselves by flapping their wings, man had only to
make suitable wings, flap them, and he too would fly. As early as
the thirteenth century Roger Bacon, the scientific friar of unbounded
inquisitiveness and not a little real genius, announced that there could
be made 'some flying instrument, so that a man sitting in the middle and
turning some mechanism may put in motion some artificial wings which
may beat the air like a bird flying.' But being a cautious man, with a
natural dislike for being burnt at the stake as a necromancer through
having put forward such a dangerous theory, Roger added, 'not that
I ever knew a man who had such an instrument, but I am particularly
acquainted with the man who contrived one.' This might have been a lame
defence if Roger had been brought to trial as addicted to black arts; he
seems to have trusted to the inadmissibility of hearsay evidence.
Some four centuries later there was published a book entitled Perugia
Augusta, written by one C. Crispolti of Perugia--the date of the work in
question is 1648. In it is recorded that 'one day, towards the close of
the fifteenth century, whilst many of the principal gentry had come
to Perugia to honour the wedding of Giovanni Paolo Baglioni, and some
lancers were riding down the street by his palace, Giovanni Baptisti
Danti unexpectedly and by means of a contrivance of wings that he had
constructed proportionate to the size of his body took off from the top
of a tower near by, and with a horrible hissing sound flew successfully
across the great Piazza, which was densely crowded. But (oh, horror of
an unexpected accident!) he had scarcely flown three hundred paces on
his way to a certain point when the mainstay of the left wing gave way,
and, being unable to support himself with the right alone, he fell on a
roof and was injured in consequence. Those who saw not only this flight,
but also the wonderful construction of the framework of the wings,
said--and tradition bears them out--that he several times flew over the
waters of Lake Thrasimene to learn how he might gradually come to earth.
But, notwithstanding his great genius, he never succeeded.'
This reads circumstantially enough, but it may be borne in mind that the
date of writing is more than half a century later than the time of the
alleged achievement--the story had had time to round itself out. Danti,
however, is mentioned by a number of writers, one of whom states that
the failure of his experiment was due to the prayers of some individual
of a conservative turn of mind, who prayed so vigorously that Danti fell
appropriately enough on a church and injured himself to such an extent
as to put an end to his flying career. That Danti experimented, there
is little doubt, in view of the volume of evidence on the point, but the
darkness of the Middle Ages hides the real truth as to the results of
his experiments. If he had actually flown over Thrasimene, as alleged,
then in all probability both Napoleon and Wellington would have had air
scouts at Waterloo.
Danti's story may be taken as fact or left as fable, and with it the
period of legend or vague statement may be said to end--the rest is
history, both of genuine experimenters and of charlatans. Such instances
of legend as are given here are not a tithe of the whole, but there is
sufficient in the actual history of flight to bar out more than this
brief mention of the legends, which, on the whole, go farther to prove
man's desire to fly than his study and endeavour to solve the problems
of the air.
II. EARLY EXPERIMENTS
So far, the stories of the development of flight are either legendary
or of more or less doubtful authenticity, even including that of Danti,
who, although a man of remarkable attainments in more directions
than that of attempted flight, suffers--so far as reputation is
concerned--from the inexactitudes of his chroniclers; he may have soared
over Thrasimene, as stated, or a mere hop with an ineffectual glider may
have grown with the years to a legend of gliding flight. So far, too,
there is no evidence of the study that the conquest of the air demanded;
such men as made experiments either launched themselves in the air from
some height with made-up wings or other apparatus, and paid the penalty,
or else constructed some form of machine which would not leave the
earth, and then gave up. Each man followed his own way, and there was no
attempt--without the printing press and the dissemination of knowledge
there was little possibility of attempt--on the part of any one to
benefit by the failures of others.
Legend and doubtful history carries up to the fifteenth century, and
then came Leonardo da Vinci, first student of flight whose work endures
to the present day. The world knows da Vinci as artist; his age knew him
as architect, engineer, artist, and scientist in an age when science was
a single study, comprising all knowledge from mathematics to medicine.
He was, of course, in league with the devil, for in no other way
could his range of knowledge and observation be explained by his
contemporaries; he left a Treatise on the Flight of Birds in which are
statements and deductions that had to be rediscovered when the Treatise
had been forgotten--da Vinci anticipated modern knowledge as Plato
anticipated modern thought, and blazed the first broad trail toward
flight.
One Cuperus, who wrote a Treatise on the Excellence of Man, asserted
that da Vinci translated his theories into practice, and actually flew,
but the statement is unsupported. That he made models, especially on
the helicopter principle, is past question; these were made of paper and
wire, and actuated by springs of steel wire, which caused them to lift
themselves in the air. It is, however, in the theories which he put
forward that da Vinci's investigations are of greatest interest; these
prove him a patient as well as a keen student of the principles of
flight, and show that his manifold activities did not prevent him from
devoting some lengthy periods to observations of bird flight.
'A bird,' he says in his Treatise, 'is an instrument working according
to mathematical law, which instrument it is within the capacity of man
to reproduce with all its movements, but not with a corresponding
degree of strength, though it is deficient only in power of maintaining
equilibrium. We may say, therefore, that such an instrument constructed
by man is lacking in nothing except the life of the bird, and this life
must needs be supplied from that of man. The life which resides in the
bird's members will, without doubt, better conform to their needs than
will that of a man which is separated from them, and especially in the
almost imperceptible movements which produce equilibrium. But since we
see that the bird is equipped for many apparent varieties of movement,
we are able from this experience to deduce that the most rudimentary
of these movements will be capable of being comprehended by man's
understanding, and that he will to a great extent be able to provide
against the destruction of that instrument of which he himself has
become the living principle and the propeller.'
In this is the definite belief of da Vinci that man is capable of
flight, together with a far more definite statement of the principles by
which flight is to be achieved than any which had preceded it--and for
that matter, than many that have succeeded it. Two further extracts from
his work will show the exactness of his observations:--
'When a bird which is in equilibrium throws the centre of resistance of
the wings behind the centre of gravity, then such a bird will descend
with its head downward. This bird which finds itself in equilibrium
shall have the centre of resistance of the wings more forward than
the bird's centre of gravity; then such a bird will fall with its tail
turned toward the earth.'
And again: 'A man, when flying, shall be free from the waist up, that he
may be able to keep himself in equilibrium as he does in a boat, so
that the centre of his gravity and of the instrument may set itself in
equilibrium and change when necessity requires it to the changing of the
centre of its resistance.'
Here, in this last quotation, are the first beginnings of the inherent
stability which proved so great an advance in design, in this twentieth
century. But the extracts given do not begin to exhaust the range of
da Vinci's observations and deductions. With regard to bird flight, he
observed that so long as a bird keeps its wings outspread it cannot fall
directly to earth, but must glide down at an angle to alight--a small
thing, now that the principle of the plane in opposition to the air is
generally grasped, but da Vinci had to find it out. From observation
he gathered how a bird checks its own speed by opposing tail and wing
surface to the direction of flight, and thus alights at the proper
'landing speed.' He proved the existence of upward air currents by
noting how a bird takes off from level earth with wings outstretched and
motionless, and, in order to get an efficient substitute for the
natural wing, he recommended that there be used something similar to
the membrane of the wing of a bat--from this to the doped fabric of an
aeroplane wing is but a small step, for both are equally impervious to
air. Again, da Vinci recommended that experiments in flight be conducted
at a good height from the ground, since, if equilibrium be lost through
any cause, the height gives time to regain it. This recommendation, by
the way, received ample support in the training areas of war pilots.
Man's muscles, said da Vinci, are fully sufficient to enable him to
fly, for the larger birds, he noted, employ but a small part of their
strength in keeping themselves afloat in the air--by this theory he
attempted to encourage experiment, just as, when his time came, Borelli
reached the opposite conclusion and discouraged it. That Borelli was
right--so far--and da Vinci wrong, detracts not at all from the repute
of the earlier investigator, who had but the resources of his age to
support investigations conducted in the spirit of ages after.
His chief practical contributions to the science of flight--apart
from numerous drawings which have still a value--are the helicopter or
lifting screw, and the parachute. The former, as already noted, he
made and proved effective in model form, and the principle which he
demonstrated is that of the helicopter of to-day, on which sundry
experimenters work spasmodically, in spite of the success of the plane
with its driving propeller. As to the parachute, the idea was doubtless
inspired by observation of the effect a bird produced by pressure of its
wings against the direction of flight.
Da Vinci's conclusions, and his experiments, were forgotten easily by
most of his contemporaries; his Treatise lay forgotten for nearly four
centuries, overshadowed, mayhap, by his other work. There was, however,
a certain Paolo Guidotti of Lucca, who lived in the latter half of the
sixteenth century, and who attempted to carry da Vinci's theories--one
of them, at least, into practice. For this Guidotti, who was by
profession an artist and by inclination an investigator, made for
himself wings, of which the framework was of whalebone; these he covered
with feathers, and with them made a number of gliding flights, attaining
considerable proficiency. He is said in the end to have made a flight of
about four hundred yards, but this attempt at solving the problem
ended on a house roof, where Guidotti broke his thigh bone. After that,
apparently, he gave up the idea of flight, and went back to painting.
One other a Venetian architect named Veranzio, studied da Vinci's theory
of the parachute, and found it correct, if contemporary records and even
pictorial presentment are correct. Da Vinci showed his conception of a
parachute as a sort of inverted square bag; Veranzio modified this to a
'sort of square sail extended by four rods of equal size and having four
cords attached at the corners,' by means of which 'a man could without
danger throw himself from the top of a tower or any high place. For
though at the moment there may be no wind, yet the effort of his falling
will carry up the wind, which the sail will hold, by which means he does
not fall suddenly but descends little by little. The size of the sail
should be measured to the man.' By this last, evidently, Veranzio
intended to convey that the sheet must be of such content as would
enclose sufficient air to support the weight of the parachutist.
Veranzio made his experiments about 1617-1618, but, naturally, they
carried him no farther than the mere descent to earth, and since a
descent is merely a descent, it is to be conjectured that he soon got
tired of dropping from high roofs, and took to designing architecture
instead of putting it to such a use. With the end of his experiments the
work of da Vinci in relation to flying became neglected for nearly four
centuries.
Apart from these two experimenters, there is little to record in the
matter either of experiment or study until the seventeenth century.
Francis Bacon, it is true, wrote about flying in his Sylva Sylvarum, and
mentioned the subject in the New Atlantis, but, except for the insight
that he showed even in superficial mention of any specific subject,
he does not appear to have made attempt at serious investigation.
'Spreading of Feathers, thin and close and in great breadth will
likewise bear up a great Weight,' says Francis, 'being even laid without
Tilting upon the sides.' But a lesser genius could have told as much,
even in that age, and though the great Sir Francis is sometimes adduced
as one of the early students of the problems of flight, his writings
will not sustain the reputation.
The seventeenth century, however, gives us three names, those of
Borelli, Lana, and Robert Hooke, all of which take definite place in
the history of flight. Borelli ranks as one of the great figures in the
study of aeronautical problems, in spite of erroneous deductions through
which he arrived at a purely negative conclusion with regard to the
possibility of human flight.
Borelli was a versatile genius. Born in 1608, he was practically
contemporary with Francesco Lana, and there is evidence that he either
knew or was in correspondence with many prominent members of the Royal
Society of Great Britain, more especially with John Collins, Dr Wallis,
and Henry Oldenburgh, the then Secretary of the Society. He was author
of a long list of scientific essays, two of which only are responsible
for his fame, viz., Theorice Medicaearum Planetarum, published in
Florence, and the better known posthumous De Motu Animalium. The first
of these two is an astronomical study in which Borelli gives evidence of
an instinctive knowledge of gravitation, though no definite expression
is given of this. The second work, De Motu Animalium, deals with the
mechanical action of the limbs of birds and animals and with a theory of
the action of the internal organs. A section of the first part of
this work, called De Volatu, is a study of bird flight; it is quite
independent of Da Vinci's earlier work, which had been forgotten and
remained unnoticed until near on the beginning of practical flight.
Marey, in his work, La Machine Animale, credits Borelli with the first
correct idea of the mechanism of flight. He says: 'Therefore we must be
allowed to render to the genius of Borelli the justice which is due
to him, and only claim for ourselves the merit of having furnished the
experimental demonstration of a truth already suspected.' In fact, all
subsequent studies on this subject concur in making Borelli the first
investigator who illustrated the purely mechanical theory of the action
of a bird's wings.
Borelli's study is divided into a series of propositions in which he
traces the principles of flight, and the mechanical actions of the wings
of birds. The most interesting of these are the propositions in which he
sets forth the method in which birds move their wings during flight and
the manner in which the air offers resistance to the stroke of the wing.
With regard to the first of these two points he says: 'When birds in
repose rest on the earth their wings are folded up close against their
flanks, but when wishing to start on their flight they first bend their
legs and leap into the air. Whereupon the joints of their wings are
straightened out to form a straight line at right angles to the lateral
surface of the breast, so that the two wings, outstretched, are placed,
as it were, like the arms of a cross to the body of the bird. Next,
since the wings with their feathers attached form almost a plane
surface, they are raised slightly above the horizontal, and with a
most quick impulse beat down in a direction almost perpendicular to the
wing-plane, upon the underlying air; and to so intense a beat the air,
notwithstanding it to be fluid, offers resistance, partly by reason
of its natural inertia, which seeks to retain it at rest, and partly
because the particles of the air, compressed by the swiftness of the
stroke, resist this compression by their elasticity, just like the hard
ground. Hence the whole mass of the bird rebounds, making a fresh
leap through the air; whence it follows that flight is simply a motion
composed of successive leaps accomplished through the air. And I remark
that a wing can easily beat the air in a direction almost perpendicular
to its plane surface, although only a single one of the corners of the
humerus bone is attached to the scapula, the whole extent of its base
remaining free and loose, while the greater transverse feathers are
joined to the lateral skin of the thorax. Nevertheless the wing can
easily revolve about its base like unto a fan. Nor are there lacking
tendon ligaments which restrain the feathers and prevent them from
opening farther, in the same fashion that sheets hold in the sails of
ships. No less admirable is nature's cunning in unfolding and folding
the wings upwards, for she folds them not laterally, but by moving
upwards edgewise the osseous parts wherein the roots of the feathers are
inserted; for thus, without encountering the air's resistance the upward
motion of the wing surface is made as with a sword, hence they can be
uplifted with but small force. But thereafter when the wings are twisted
by being drawn transversely and by the resistance of the air, they are
flattened as has been declared and will be made manifest hereafter.'
Then with reference to the resistance to the air of the wings he
explains: 'The air when struck offers resistance by its elastic virtue
through which the particles of the air compressed by the wing-beat
strive to expand again. Through these two causes of resistance the
downward beat of the wing is not only opposed, but even caused to recoil
with a reflex movement; and these two causes of resistance ever increase
the more the down stroke of the wing is maintained and accelerated. On
the other hand, the impulse of the wing is continuously diminished and
weakened by the growing resistance. Hereby the force of the wing and the
resistance become balanced; so that, manifestly, the air is beaten by
the wing with the same force as the resistance to the stroke.'
He concerns himself also with the most difficult problem that confronts
the flying man of to-day, namely, landing effectively, and his remarks
on this subject would be instructive even to an air pilot of these days:
'Now the ways and means by which the speed is slackened at the end of
a flight are these. The bird spreads its wings and tail so that their
concave surfaces are perpendicular to the direction of motion; in this
way, the spreading feathers, like a ship's sail, strike against the
still air, check the speed, and so that most of the impetus may be
stopped, the wings are flapped quickly and strongly forward, inducing a
contrary motion, so that the bird absolutely or very nearly stops.'
At the end of his study Borelli came to a conclusion which militated
greatly against experiment with any heavier-than-air apparatus, until
well on into the nineteenth century, for having gone thoroughly into the
subject of bird flight he states distinctly in his last proposition
on the subject that 'It is impossible that men should be able to fly
craftily by their own strength.' This statement, of course, remains true
up to the present day for no man has yet devised the means by which he
can raise himself in the air and maintain himself there by mere muscular
effort.
From the time of Borelli up to the development of the steam engine it
may be said that flight by means of any heavier-than-air apparatus was
generally regarded as impossible, and apart from certain deductions
which a little experiment would have shown to be doomed to failure, this
method of flight was not followed up. It is not to be wondered at, when
Borelli's exaggerated estimate of the strength expended by birds in
proportion to their weight is borne in mind; he alleged that the motive
force in birds' wings is 10,000 times greater than the resistance of
their weight, and with regard to human flight he remarks:--
'When, therefore, it is asked whether men may be able to fly by their
own strength, it must be seen whether the motive power of the pectoral
muscles (the strength of which is indicated and measured by their size)
is proportionately great, as it is evident that it must exceed the
resistance of the weight of the whole human body 10,000 times, together
with the weight of enormous wings which should be attached to the arms.
And it is clear that the motive power of the pectoral muscles in men is
much less than is necessary for flight, for in birds the bulk and weight
of the muscles for flapping the wings are not less than a sixth part of
the entire weight of the body. Therefore, it would be necessary that
the pectoral muscles of a man should weigh more than a sixth part of the
entire weight of his body; so also the arms, by flapping with the wings
attached, should be able to exert a power 10,000 times greater than the
weight of the human body itself. But they are far below such excess,
for the aforesaid pectoral muscles do not equal a hundredth part of the
entire weight of a man. Wherefore either the strength of the muscles
ought to be increased or the weight of the human body must be decreased,
so that the same proportion obtains in it as exists in birds. Hence
it is deducted that the Icarian invention is entirely mythical because
impossible, for it is not possible either to increase a man's pectoral
muscles or to diminish the weight of the human body; and whatever
apparatus is used, although it is possible to increase the momentum,
the velocity or the power employed can never equal the resistance; and
therefore wing flapping by the contraction of muscles cannot give out
enough power to carry up the heavy body of a man.'
It may be said that practically all the conclusions which Borelli
reached in his study were negative. Although contemporary with Lana,
he perceived the one factor which rendered Lana's project for flight by
means of vacuum globes an impossibility--he saw that no globe could
be constructed sufficiently light for flight, and at the same time
sufficiently strong to withstand the pressure of the outside atmosphere.
He does not appear to have made any experiments in flying on his
own account, having, as he asserts most definitely, no faith in any
invention designed to lift man from the surface of the earth. But his
work, from which only the foregoing short quotations can be given, is,
nevertheless, of indisputable value, for he settled the mechanics of
bird flight, and paved the way for those later investigators who had,
first, the steam engine, and later the internal combustion engine--two
factors in mechanical flight which would have seemed as impossible to
Borelli as would wireless telegraphy to a student of Napoleonic times.
On such foundations as his age afforded Borelli built solidly and
well, so that he ranks as one of the greatest--if not actually the
greatest--of the investigators into this subject before the age of
steam.
The conclusion, that 'the motive force in birds' wings is apparently
ten thousand times greater than the resistance of their weight,' is
erroneous, of course, but study of the translation from which the
foregoing excerpt is taken will show that the error detracts very little
from the value of the work itself. Borelli sets out very definitely
the mechanism of flight, in such fashion that he who runs may read. His
reference to 'the use of a large vessel,' etc., concerns the suggestion
made by Francesco Lana, who antedated Borelli's publication of De Motu
Animalium by some ten years with his suggestion for an 'aerial ship,' as
he called it. Lana's mind shows, as regards flight, a more imaginative
twist; Borelli dived down into first causes, and reached mathematical
conclusions; Lana conceived a theory and upheld it--theoretically, since
the manner of his life precluded experiment.
Francesco Lana, son of a noble family, was born in 1631; in 1647 he was
received as a novice into the Society of Jesus at Rome, and remained
a pious member of the Jesuit society until the end of his life. He was
greatly handicapped in his scientific investigations by the vows
of poverty which the rules of the Order imposed on him. He was more
scientist than priest all his life; for two years he held the post of
Professor of Mathematics at Ferrara, and up to the time of his death,
in 1687, he spent by far the greater part of his time in scientific
research, He had the dubious advantage of living in an age when one man
could cover the whole range of science, and this he seems to have
done very thoroughly. There survives an immense work of his entitled,
Magisterium Naturae et Artis, which embraces the whole field of
scientific knowledge as that was developed in the period in which Lana
lived. In an earlier work of his, published in Brescia in 1670, appears
his famous treatise on the aerial ship, a problem which Lana worked out
with thoroughness. He was unable to make practical experiments, and thus
failed to perceive the one insuperable drawback to his project--of which
more anon.
Only extracts from the translation of Lana's work can be given here, but
sufficient can be given to show fully the means by which he designed to
achieve the conquest of the air. He begins by mention of the celebrated
pigeon of Archytas the Philosopher, and advances one or two theories
with regard to the way in which this mechanical bird was constructed,
and then he recites, apparently with full belief in it, the fable of
Regiomontanus and the eagle that he is said to have constructed to
accompany Charles V. on his entry into Nuremberg. In fact, Lana starts
his work with a study of the pioneers of mechanical flying up to his
own time, and then outlines his own devices for the construction of
mechanical birds before proceeding to detail the construction of the
aerial ship. Concerning primary experiments for this he says:--
'I will, first of all, presuppose that air has weight owing to the
vapours and halations which ascend from the earth and seas to a height
of many miles and surround the whole of our terraqueous globe; and this
fact will not be denied by philosophers, even by those who may have but
a superficial knowledge, because it can be proven by exhausting, if
not all, at any rate the greater part of, the air contained in a glass
vessel, which, if weighed before and after the air has been exhausted,
will be found materially reduced in weight. Then I found out how much
the air weighed in itself in the following manner. I procured a large
vessel of glass, whose neck could be closed or opened by means of a tap,
and holding it open I warmed it over a fire, so that the air inside it
becoming rarified, the major part was forced out; then quickly shutting
the tap to prevent the re-entry I weighed it; which done, I plunged its
neck in water, resting the whole of the vessel on the surface of the
water, then on opening the tap the water rose in the vessel and filled
the greater part of it. I lifted the neck out of the water, released the
water contained in the vessel, and measured and weighed its quantity and
density, by which I inferred that a certain quantity of air had come out
of the vessel equal in bulk to the quantity of water which had entered
to refill the portion abandoned by the air. I again weighed the vessel,
after I had first of all well dried it free of all moisture, and found
it weighed one ounce more whilst it was full of air than when it was
exhausted of the greater part, so that what it weighed more was a
quantity of air equal in volume to the water which took its place. The
water weighed 640 ounces, so I concluded that the weight of air compared
with that of water was 1 to 640--that is to say, as the water which
filled the vessel weighed 640 ounces, so the air which filled the same
vessel weighed one ounce.'
Having thus detailed the method of exhausting air from a vessel, Lana
goes on to assume that any large vessel can be entirely exhausted of
nearly all the air contained therein. Then he takes Euclid's proposition
to the effect that the superficial area of globes increases in the
proportion of the square of the diameter, whilst the volume increases in
the proportion of the cube of the same diameter, and he considers that
if one only constructs the globe of thin metal, of sufficient size, and
exhausts the air in the manner that he suggests, such a globe will be so
far lighter than the surrounding atmosphere that it will not only
rise, but will be capable of lifting weights. Here is Lana's own way of
putting it:--
'But so that it may be enabled to raise heavier weights and to lift
men in the air, let us take double the quantity of copper, 1,232 square
feet, equal to 308 lbs. of copper; with this double quantity of copper
we could construct a vessel of not only double the capacity, but of
four times the capacity of the first, for the reason shown by my fourth
supposition. Consequently the air contained in such a vessel will be 718
lbs. 4 2/3 ounces, so that if the air be drawn out of the vessel it
will be 410 lbs. 4 2/3 ounces lighter than the same volume of air, and,
consequently, will be enabled to lift three men, or at least two, should
they weigh more than eight pesi each. It is thus manifest that the
larger the ball or vessel is made, the thicker and more solid can the
sheets of copper be made, because, although the weight will increase,
the capacity of the vessel will increase to a greater extent and with it
the weight of the air therein, so that it will always be capable to lift
a heavier weight. From this it can be easily seen how it is possible to
construct a machine which, fashioned like unto a ship, will float on the
air.'
With four globes of these dimensions Lana proposed to make an aerial
ship of the fashion shown in his quaint illustration. He is careful to
point out a method by which the supporting globes for the aerial ship
may be entirely emptied of air; (this is to be done by connecting to each
globe a tube of copper which is 'at least a length of 47 modern Roman
palm).' A small tap is to close this tube at the end nearest the globe,
and then vessel and tube are to be filled with water, after which the
tube is to be immersed in water and the tap opened, allowing the water
to run out of the vessel, while no air enters. The tap is then closed
before the lower end of the tube is removed from the water, leaving no
air at all in the globe or sphere. Propulsion of this airship was to be
accomplished by means of sails, and also by oars.
Lana antedated the modern propeller, and realised that the air would
offer enough resistance to oars or paddle to impart motion to any vessel
floating in it and propelled by these means, although he did not realise
the amount of pressure on the air which would be necessary to accomplish
propulsion. As a matter of fact, he foresaw and provided against
practically all the difficulties that would be encountered in the
working, as well as the making, of the aerial ship, finally coming up
against what his religious training made an insuperable objection. This,
again, is best told in his own words:--
'Other difficulties I do not foresee that could prevail against this
invention, save one only, which to me seems the greatest of them all,
and that is that God would surely never allow such a machine to be
successful, since it would create many disturbances in the civil and
political governments of mankind.'
He ends by saying that no city would be proof against surprise, while
the aerial ship could set fire to vessels at sea, and destroy houses,
fortresses, and cities by fire balls and bombs. In fact, at the end of
his treatise on the subject, he furnishes a pretty complete resume of
the activities of German Zeppelins.
As already noted, Lana himself, owing to his vows of poverty, was
unable to do more than put his suggestions on paper, which he did with
a thoroughness that has procured him a place among the really great
pioneers of flying.
It was nearly 200 years before any attempt was made to realise his
project; then, in 1843, M. Marey Monge set out to make the globes and
the ship as Lana detailed them. Monge's experiments cost him the sum
of 25,000 francs 75 centimes, which he expended purely from love
of scientific investigation. He chose to make his globes of brass,
about.004 in thickness, and weighing 1.465 lbs. to the square yard.
Having made his sphere of this metal, he lined it with two thicknesses
of tissue paper, varnished it with oil, and set to work to empty it of
air. This, however, he never achieved, for such metal is incapable of
sustaining the pressure of the outside air, as Lana, had he had the
means to carry out experiments, would have ascertained. M. Monge's
sphere could never be emptied of air sufficiently to rise from the
earth; it ended in the melting-pot, ignominiously enough, and all that
Monge got from his experiment was the value of the scrap metal and the
satisfaction of knowing that Lana's theory could never be translated
into practice.
Robert Hooke is less conspicuous than either Borelli or Lana; his work,
which came into the middle of the seventeenth century, consisted of
various experiments with regard to flight, from which emerged 'a Module,
which by the help of Springs and Wings, raised and sustained itself in
the air.' This must be reckoned as the first model flying machine which
actually flew, except for da Vinci's helicopters; Hooke's model appears
to have been of the flapping-wing type--he attempted to copy the motion
of birds, but found from study and experiment that human muscles were
not sufficient to the task of lifting the human body. For that reason,
he says, 'I applied my mind to contrive a way to make artificial
muscles,' but in this he was, as he expresses it, 'frustrated of my
expectations.' Hooke's claim to fame rests mainly on his successful
model; the rest of his work is of too scrappy a nature to rank as a
serious contribution to the study of flight.
Contemporary with Hooke was one Allard, who, in France, undertook to
emulate the Saracen of Constantinople to a certain extent. Allard was a
tight-rope dancer who either did or was said to have done short gliding
flights--the matter is open to question--and finally stated that he
would, at St Germains, fly from the terrace in the king's presence. He
made the attempt, but merely fell, as did the Saracen some centuries
before, causing himself serious injury. Allard cannot be regarded as a
contributor to the development of aeronautics in any way, and is only
mentioned as typical of the way in which, up to the time of the Wright
brothers, flying was regarded. Even unto this day there are many who
still believe that, with a pair of wings, man ought to be able to fly,
and that the mathematical data necessary to effective construction
simply do not exist. This attitude was reasonable enough in an
unlearned age, and Allard was one--a little more conspicuous than the
majority--among many who made experiment in ignorance, with more or less
danger to themselves and without practical result of any kind.
The seventeenth century was not to end, however, without practical
experiment of a noteworthy kind in gliding flight. Among the recruits to
the ranks of pioneers was a certain Besnier, a locksmith of Sable, who
somewhere between 1675 and 1680 constructed a glider of which a crude
picture has come down to modern times. The apparatus, as will be seen,
consisted of two rods with hinged flaps, and the original designer of
the picture seems to have had but a small space in which to draw, since
obviously the flaps must have been much larger than those shown. Besnier
placed the rods on his shoulders, and worked the flaps by cords attached
to his hands and feet--the flaps opened as they fell, and closed as they
rose, so the device as a whole must be regarded as a sort of flapping
glider. Having by experiment proved his apparatus successful, Besnier
promptly sold it to a travelling showman of the period, and forthwith
set about constructing a second set, with which he made gliding flights
of considerable height and distance. Like Lilienthal, Besnier projected
himself into space from some height, and then, according to the
contemporary records, he was able to cross a river of considerable size
before coming to earth. It does not appear that he had any imitators,
or that any advantage whatever was taken of his experiments; the age was
one in which he would be regarded rather as a freak exhibitor than as
a serious student, and possibly, considering his origin and the sale of
his first apparatus to such a client, he regarded the matter himself as
more in the nature of an amusement than as a discovery.
Borelli, coming at the end of the century, proved to his own
satisfaction and that of his fellows that flapping wing flight was an
impossibility; the capabilities of the plane were as yet undreamed, and
the prime mover that should make the plane available for flight was
deep in the womb of time. Da Vinci's work was forgotten--flight was an
impossibility, or at best such a useless show as Besnier was able to
give.
The eighteenth century was almost barren of experiment. Emanuel
Swedenborg, having invented a new religion, set about inventing a flying
machine, and succeeded theoretically, publishing the result of his
investigations as follows:--
'Let a car or boat or some like object be made of light material such as
cork or bark, with a room within it for the operator. Secondly, in front
as well as behind, or all round, set a widely-stretched sail parallel to
the machine forming within a hollow or bend which could be reefed like
the sails of a ship. Thirdly, place wings on the sides, to be worked
up and down by a spiral spring, these wings also to be hollow below in
order to increase the force and velocity, take in the air, and make the
resistance as great as may be required. These, too, should be of light
material and of sufficient size; they should be in the shape of birds'
wings, or the sails of a windmill, or some such shape, and should be
tilted obliquely upwards, and made so as to collapse on the upward
stroke and expand on the downward. Fourth, place a balance or beam
below, hanging down perpendicularly for some distance with a small
weight attached to its end, pendent exactly in line with the centre of
gravity; the longer this beam is, the lighter must it be, for it must
have the same proportion as the well-known vectis or steel-yard. This
would serve to restore the balance of the machine if it should lean over
to any of the four sides. Fifthly, the wings would perhaps have greater
force, so as to increase the resistance and make the flight easier, if
a hood or shield were placed over them, as is the case with certain
insects. Sixthly, when the sails are expanded so as to occupy a great
surface and much air, with a balance keeping them horizontal, only a
small force would be needed to move the machine back and forth in a
circle, and up and down. And, after it has gained momentum to move
slowly upwards, a slight movement and an even bearing would keep it
balanced in the air and would determine its direction at will.'
The only point in this worthy of any note is the first device for
maintaining stability automatically--Swedenborg certainly scored a point
there. For the rest, his theory was but theory, incapable of being put
to practice--he does not appear to have made any attempt at advance
beyond the mere suggestion.
Some ten years before his time the state of knowledge with regard to
flying in Europe was demonstrated by an order granted by the King of
Portugal to Friar Lourenzo de Guzman, who claimed to have invented a
flying machine capable of actual flight. The order stated that 'In
order to encourage the suppliant to apply himself with zeal toward
the improvement of the new machine, which is capable of producing the
effects mentioned by him, I grant unto him the first vacant place in
my College of Barcelos or Santarem, and the first professorship of
mathematics in my University of Coimbra, with the annual pension of
600,000 reis during his life.--Lisbon, 17th of March, 1709.'
What happened to Guzman when the non-existence of the machine was
discovered is one of the things that is well outside the province of
aeronautics. He was charlatan pure and simple, as far as actual flight
was concerned, though he had some ideas respecting the design of hot-air
balloons, according to Tissandier. (La Navigation Aerienne.) His
flying machine was to contain, among other devices, bellows to produce
artificial wind when the real article failed, and also magnets in globes
to draw the vessel in an upward direction and maintain its buoyancy.
Some draughtsman, apparently gifted with as vivid imagination as Guzman
himself, has given to the world an illustration of the hypothetical
vessel; it bears some resemblance to Lana's aerial ship, from which fact
one draws obvious conclusions.
A rather amusing claim to solving the problem of flight was made in the
middle of the eighteenth century by one Grimaldi, a 'famous and unique
Engineer' who, as a matter of actual fact, spent twenty years in
missionary work in India, and employed the spare time that missionary
work left him in bringing his invention to a workable state. The
invention is described as a 'box which with the aid of clockwork rises
in the air, and goes with such lightness and strong rapidity that it
succeeds in flying a journey of seven leagues in an hour. It is made in
the fashion of a bird; the wings from end to end are 25 feet in extent.
The body is composed of cork, artistically joined together and well
fastened with metal wire, covered with parchment and feathers. The
wings are made of catgut and whalebone, and covered also with the same
parchment and feathers, and each wing is folded in three seams. In the
body of the machine are contained thirty wheels of unique work, with two
brass globes and little chains which alternately wind up a counterpoise;
with the aid of six brass vases, full of a certain quantity of
quicksilver, which run in some pulleys, the machine is kept by the
artist in due equilibrium and balance. By means, then, of the friction
between a steel wheel adequately tempered and a very heavy and
surprising piece of lodestone, the whole is kept in a regulated forward
movement, given, however, a right state of the winds, since the machine
cannot fly so much in totally calm weather as in stormy. This prodigious
machine is directed and guided by a tail seven palmi long, which is
attached to the knees and ankles of the inventor by leather straps; by
stretching out his legs, either to the right or to the left, he moves
the machine in whichever direction he pleases.... The machine's
flight lasts only three hours, after which the wings gradually close
themselves, when the inventor, perceiving this, goes down gently, so as
to get on his own feet, and then winds up the clockwork and gets himself
ready again upon the wings for the continuation of a new flight. He
himself told us that if by chance one of the wheels came off or if one
of the wings broke, it is certain he would inevitably fall rapidly to
the ground, and, therefore, he does not rise more than the height of a
tree or two, as also he only once put himself in the risk of crossing
the sea, and that was from Calais to Dover, and the same morning he
arrived in London.'
And yet there are still quite a number of people who persist in stating
that Bleriot was the first man to fly across the Channel!
A study of the development of the helicopter principle was published
in France in 1868, when the great French engineer Paucton produced his
Theorie de la Vis d'Archimede. For some inexplicable reason, Paucton
was not satisfied with the term 'helicopter,' but preferred to call it
a 'pterophore,' a name which, so far as can be ascertained, has not been
adopted by any other writer or investigator. Paucton stated that, since
a man is capable of sufficient force to overcome the weight of his own
body, it is only necessary to give him a machine which acts on the air
'with all the force of which it is capable and at its utmost speed,' and
he will then be able to lift himself in the air, just as by the exertion
of all his strength he is able to lift himself in water. 'It would
seem,' says Paucton, 'that in the pterophore, attached vertically to a
carriage, the whole built lightly and carefully assembled, he has
found something that will give him this result in all perfection. In
construction, one would be careful that the machine produced the least
friction possible, and naturally it ought to produce little, as it would
not be at all complicated. The new Daedalus, sitting comfortably in his
carriage, would by means of a crank give to the pterophore a suitable
circular (or revolving) speed. This single pterophore would lift him
vertically, but in order to move horizontally he should be supplied with
a tail in the shape of another pterophore. When he wished to stop for a
little time, valves fixed firmly across the end of the space between
the blades would automatically close the openings through which the air
flows, and change the pterophore into an unbroken surface which
would resist the flow of air and retard the fall of the machine to a
considerable degree.'
The doctrine thus set forth might appear plausible, but it is based on
the common misconception that all the force which might be put into the
helicopter or 'pterophore' would be utilised for lifting or propelling
the vehicle through the air, just as a propeller uses all its power to
drive a ship through water. But, in applying such a propelling force
to the air, most of the force is utilised in maintaining aerodynamic
support--as a matter of fact, more force is needed to maintain this
support than the muscle of man could possibly furnish to a lifting
screw, and even if the helicopter were applied to a full-sized,
engine-driven air vehicle, the rate of ascent would depend on the amount
of surplus power that could be carried. For example, an upward lift
of 1,000 pounds from a propeller 15 feet in diameter would demand an
expenditure of 50 horse-power under the best possible conditions, and in
order to lift this load vertically through such atmospheric pressure as
exists at sea-level or thereabouts, an additional 20 horsepower would be
required to attain a rate of 11 feet per second--50 horse-power must
be continually provided for the mere support of the load, and the
additional 20 horse-power must be continually provided in order to
lift it. Although, in model form, there is nothing quite so strikingly
successful as the helicopter in the range of flying machines, yet the
essential weight increases so disproportionately to the effective area
that it is necessary to go but very little beyond model dimensions for
the helicopter to become quite ineffective.
That is not to say that the lifting screw must be totally ruled out
so far as the construction of aircraft is concerned. Much is still
empirical, so far as this branch of aeronautics is concerned, and
consideration of the structural features of a propeller goes to show
that the relations of essential weight and effective area do not
altogether apply in practice as they stand in theory. Paucton's dream,
in some modified form, may yet become reality--it is only so short
a time ago as 1896 that Lord Kelvin stated he had not the smallest
molecule of faith in aerial navigation, and since the whole history of
flight consists in proving the impossible possible, the helicopter may
yet challenge the propelled plane surface for aerial supremacy.
It does not appear that Paucton went beyond theory, nor is there in his
theory any advance toward practical flight--da Vinci could have told
him as much as he knew. He was followed by Meerwein, who invented an
apparatus apparently something between a flapping wing machine and a
glider, consisting of two wings, which were to be operated by means of a
rod; the venturesome one who would fly by means of this apparatus had to
lie in a horizontal position beneath the wings to work the rod. Meerwein
deserves a place of mention, however, by reason of his investigations
into the amount of surface necessary to support a given weight. Taking
that weight at 200 pounds--which would allow for the weight of a man
and a very light apparatus--he estimated that 126 square feet would be
necessary for support. His pamphlet, published at Basle in 1784, shows
him to have been a painstaking student of the potentialities of flight.
Jean-Pierre Blanchard, later to acquire fame in connection with balloon
flight, conceived and described a curious vehicle, of which he even
announced trials as impending. His trials were postponed time after
time, and it appears that he became convinced in the end of the futility
of his device, being assisted to such a conclusion by Lalande, the
astronomer, who repeated Borelli's statement that it was impossible for
man ever to fly by his own strength. This was in the closing days of
the French monarchy, and the ascent of the Montgolfiers' first hot-air
balloon in 1783--which shall be told more fully in its place--put an
end to all French experiments with heavier-than-air apparatus, though in
England the genius of Cayley was about to bud, and even in France there
were those who understood that ballooning was not true flight.
III. SIR GEORGE CAYLEY--THOMAS WALKER
On the fifth of June, 1783, the Montgolfiers' hot-air balloon rose at
Versailles, and in its rising divided the study of the conquest of the
air into two definite parts, the one being concerned with the
propulsion of gas lifted, lighter-than-air vehicles, and the other being
crystallised in one sentence by Sir George Cayley: 'The whole problem,'
he stated, 'is confined within these limits, viz.: to make a surface
support a given weight by the application of power to the resistance of
the air.' For about ten years the balloon held the field entirely, being
regarded as the only solution of the problem of flight that man could
ever compass. So definite for a time was this view on the eastern side
of the Channel that for some years practically all the progress that was
made in the development of power-driven planes was made in Britain.
In 1800 a certain Dr Thomas Young demonstrated that certain curved
surfaces suspended by a thread moved into and not away from a horizontal
current of air, but the demonstration, which approaches perilously near
to perpetual motion if the current be truly horizontal, has never been
successfully repeated, so that there is more than a suspicion that
Young's air-current was NOT horizontal. Others had made and were making
experiments on the resistance offered to the air by flat surfaces, when
Cayley came to study and record, earning such a place among the pioneers
as to win the title of 'father of British aeronautics.'
Cayley was a man in advance of his time, in many ways. Of independent
means, he made the grand tour which was considered necessary to the
education of every young man of position, and during this excursion he
was more engaged in studies of a semi-scientific character than in the
pursuits that normally filled such a period. His various writings prove
that throughout his life aeronautics was the foremost subject in his
mind; the Mechanic's Magazine, Nicholson's Journal, the Philosophical
Magazine, and other periodicals of like nature bear witness to Cayley's
continued research into the subject of flight. He approached the subject
after the manner of the trained scientist, analysing the mechanical
properties of air under chemical and physical action. Then he set to
work to ascertain the power necessary for aerial flight, and was one of
the first to enunciate the fallacy of the hopes of successful flight by
means of the steam engine of those days, owing to the fact that it was
impossible to obtain a given power with a given weight.
Yet his conclusions on this point were not altogether negative, for as
early as 1810 he stated that he could construct a balloon which could
travel with passengers at 20 miles an hour--he was one of the first to
consider the possibilities of applying power to a balloon. Nearly thirty
years later--in 1837--he made the first attempt at establishing an
aeronautical society, but at that time the power-driven plane was
regarded by the great majority as an absurd dream of more or less mad
inventors, while ballooning ranked on about the same level as tight-rope
walking, being considered an adjunct to fairs and fetes, more a pastime
than a study.
Up to the time of his death, in 1857, Cayley maintained his study of
aeronautical matters, and there is no doubt whatever that his work
went far in assisting the solution of the problem of air conquest. His
principal published work, a monograph entitled Aerial Navigation, has
been republished in the admirable series of 'Aeronautical Classics'
issued by the Royal Aeronautical Society. He began this work by
pointing out the impossibility of flying by means of attached wings, an
impossibility due to the fact that, while the pectoral muscles of a bird
account for more than two-thirds of its whole muscular strength, in a
man the muscles available for flying, no matter what mechanism might be
used, would not exceed one-tenth of his total strength.
Cayley did not actually deny the possibility of a man flying by muscular
effort, however, but stated that 'the flight of a strong man by great
muscular exertion, though a curious and interesting circumstance,
inasmuch as it will probably be the means of ascertaining finis power
and supplying the basis whereon to improve it, would be of little use.'
From this he goes on to the possibility of using a Boulton and Watt
steam engine to develop the power necessary for flight, and in this he
saw a possibility of practical result. It is worthy of note that in
this connection he made mention of the forerunner of the modern internal
combustion engine; 'The French,' he said, 'have lately shown the great
power produced by igniting inflammable powders in closed vessels,
and several years ago an engine was made to work in this country in
a similar manner by inflammation of spirit of tar.' In a subsequent
paragraph of his monograph he anticipates almost exactly the
construction of the Lenoir gas engine, which came into being more than
fifty-five years after his monograph was published.
Certain experiments detailed in his work were made to ascertain the
size of the surface necessary for the support of any given weight.
He accepted a truism of to-day in pointing out that in any matters
connected with aerial investigation, theory and practice are as
widely apart as the poles. Inclined at first to favour the helicopter
principle, he finally rejected this in favour of the plane, with which
he made numerous experiments. During these, he ascertained the peculiar
advantages of curved surfaces, and saw the necessity of providing both
vertical and horizontal rudders in order to admit of side steering
as well as the control of ascent and descent, and for preserving
equilibrium. He may be said to have anticipated the work of Lilienthal
and Pilcher, since he constructed and experimented with a fixed surface
glider. 'It was beautiful,' he wrote concerning this, 'to see this noble
white bird sailing majestically from the top of a hill to any given
point of the plain below it with perfect steadiness and safety,
according to the set of its rudder, merely by its own weight, descending
at an angle of about eight degrees with the horizon.'
It is said that he once persuaded his gardener to trust himself in this
glider for a flight, but if Cayley himself ventured a flight in it he
has left no record of the fact. The following extract from his work,
Aerial Navigation, affords an instance of the thoroughness of his
investigations, and the concluding paragraph also shows his faith in the
ultimate triumph of mankind in the matter of aerial flight:--
'The act of flying requires less exertion than from the appearance is
supposed. Not having sufficient data to ascertain the exact degree of
propelling power exerted by birds in the act of flying, it is uncertain
what degree of energy may be required in this respect for vessels of
aerial navigation; yet when we consider the many hundreds of miles of
continued flight exerted by birds of passage, the idea of its being only
a small effort is greatly corroborated. To apply the power of the first
mover to the greatest advantage in producing this effect is a very
material point. The mode universally adopted by Nature is the oblique
waft of the wing. We have only to choose between the direct beat
overtaking the velocity of the current, like the oar of a boat, or
one applied like the wing, in some assigned degree of obliquity to it.
Suppose 35 feet per second to be the velocity of an aerial vehicle, the
oar must be moved with this speed previous to its being able to receive
any resistance; then if it be only required to obtain a pressure of
one-tenth of a lb. upon each square foot it must exceed the velocity of
the current 7.3 feet per second. Hence its whole velocity must be 42.5
feet per second. Should the same surface be wafted downward like a wing
with the hinder edge inclined upward in an angle of about 50 deg. 40
feet to the current it will overtake it at a velocity of 3.5 feet per
second; and as a slight unknown angle of resistance generates a lb.
pressure per square foot at this velocity, probably a waft of a little
more than 4 feet per second would produce this effect, one-tenth part
of which would be the propelling power. The advantage of this mode of
application compared with the former is rather more than ten to one.
'In continuing the general principles of aerial navigation, for the
practice of the art, many mechanical difficulties present themselves
which require a considerable course of skilfully applied experiments
before they can be overcome; but, to a certain extent, the air has
already been made navigable, and no one who has seen the steadiness
with which weights to the amount of ten stone (including four stone,
the weight of the machine) hover in the air can doubt of the ultimate
accomplishment of this object.'
This extract from his work gives but a faint idea of the amount of
research for which Cayley was responsible. He had the humility of the
true investigator in scientific problems, and so far as can be seen
was never guilty of the great fault of so many investigators in this
subject--that of making claims which he could not support. He was
content to do, and pass after having recorded his part, and although
nearly half a century had to pass between the time of his death and the
first actual flight by means of power-driven planes, yet he may be said
to have contributed very largely to the solution of the problem, and his
name will always rank high in the roll of the pioneers of flight.
Practically contemporary with Cayley was Thomas Walker, concerning whom
little is known save that he was a portrait painter of Hull, where
was published his pamphlet on The Art of Flying in 1810, a second and
amplified edition being produced, also in Hull, in 1831. The pamphlet,
which has been reproduced in extenso in the Aeronautical Classics series
published by the Royal Aeronautical Society, displays a curious mixture
of the true scientific spirit and colossal conceit. Walker appears to
have been a man inclined to jump to conclusions, which carried him up to
the edge of discovery and left him vacillating there.
The study of the two editions of his pamphlet side by side shows that
their author made considerable advances in the practicability of his
designs in the 21 intervening years, though the drawings which accompany
the text in both editions fail to show anything really capable
of flight. The great point about Walker's work as a whole is its
suggestiveness; he did not hesitate to state that the 'art' of flying is
as truly mechanical as that of rowing a boat, and he had some conception
of the necessary mechanism, together with an absolute conviction that he
knew all there was to be known. 'Encouraged by the public,' he says,
'I would not abandon my purpose of making still further exertions to
advance and complete an art, the discovery of the TRUE PRINCIPLES (the
italics are Walker's own) of which, I trust, I can with certainty affirm
to be my own.'
The pamphlet begins with Walker's admiration of the mechanism of flight
as displayed by birds. 'It is now almost twenty years,' he says, 'since
I was first led to think, by the study of birds and their means of
flying, that if an artificial machine were formed with wings in exact
imitation of the mechanism of one of those beautiful living machines,
and applied in the very same way upon the air, there could be no doubt
of its being made to fly, for it is an axiom in philosophy that the same
cause will ever produce the same effect.' With this he confesses his
inability to produce the said effect through lack of funds, though he
clothes this delicately in the phrase 'professional avocations and other
circumstances.' Owing to this inability he published his designs that
others might take advantage of them, prefacing his own researches with
a list of the very early pioneers, and giving special mention to
Friar Bacon, Bishop Wilkins, and the Portuguese friar, De Guzman. But,
although he seems to suggest that others should avail themselves of
his theoretical knowledge, there is a curious incompleteness about the
designs accompanying his work, and about the work itself, which seems
to suggest that he had more knowledge to impart than he chose to make
public--or else that he came very near to complete solution of the
problem of flight, and stayed on the threshold without knowing it.
After a dissertation upon the history and strength of the condor, and
on the differences between the weights of birds, he says: 'The following
observations upon the wonderful difference in the weight of some birds,
with their apparent means of supporting it in their flight, may tend
to remove some prejudices against my plan from the minds of some of
my readers. The weight of the humming-bird is one drachm, that of the
condor not less than four stone. Now, if we reduce four stone into
drachms we shall find the condor is 14,336 times as heavy as the
humming-bird. What an amazing disproportion of weight! Yet by the same
mechanical use of its wings the condor can overcome the specific gravity
of its body with as much ease as the little humming-bird. But this is
not all. We are informed that this enormous bird possesses a power in
its wings, so far exceeding what is necessary for its own conveyance
through the air, that it can take up and fly away with a whole sheer in
its talons, with as much ease as an eagle would carry off, in the same
manner, a hare or a rabbit. This we may readily give credit to, from the
known fact of our little kestrel and the sparrow-hawk frequently flying
off with a partridge, which is nearly three times the weight of these
rapacious little birds.'
After a few more observations he arrives at the following conclusion:
'By attending to the progressive increase in the weight of birds, from
the delicate little humming-bird up to the huge condor, we clearly
discover that the addition of a few ounces, pounds, or stones, is no
obstacle to the art of flying; the specific weight of birds avails
nothing, for by their possessing wings large enough, and sufficient
power to work them, they can accomplish the means of flying equally well
upon all the various scales and dimensions which we see in nature. Such
being a fact, in the name of reason and philosophy why shall not man,
with a pair of artificial wings, large enough, and with sufficient power
to strike them upon the air, be able to produce the same effect?'
Walker asserted definitely and with good ground that muscular effort
applied without mechanism is insufficient for human flight, but he
states that if an aeronautical boat were constructed so that a man could
sit in it in the same manner as when rowing, such a man would be able to
bring into play his whole bodily strength for the purpose of flight,
and at the same time would be able to get an additional advantage by
exerting his strength upon a lever. At first he concluded there must
be expansion of wings large enough to resist in a sufficient degree
the specific gravity of whatever is attached to them, but in the second
edition of his work he altered this to 'expansion of flat passive
surfaces large enough to reduce the force of gravity so as to float
the machine upon the air with the man in it.' The second requisite is
strength enough to strike the wings with sufficient force to complete
the buoyancy and give a projectile motion to the machine. Given
these two requisites, Walker states definitely that flying must be
accomplished simply by muscular exertion. 'If we are secure of these two
requisites, and I am very confident we are, we may calculate upon the
success of flight with as much certainty as upon our walking.'
Walker appears to have gained some confidence from the experiments of a
certain M. Degen, a watchmaker of Vienna, who, according to the Monthly
Magazine of September, 1809, invented a machine by means of which a
person might raise himself into the air. The said machine, according to
the magazine, was formed of two parachutes which might be folded up or
extended at pleasure, while the person who worked them was placed in the
centre. This account, however, was rather misleading, for the magazine
carefully avoided mention of a balloon to which the inventor fixed his
wings or parachutes. Walker, knowing nothing of the balloon, concluded
that Degen actually raised himself in the air, though he is doubtful
of the assertion that Degen managed to fly in various directions,
especially against the wind.
Walker, after considering Degen and all his works, proceeds to detail
his own directions for the construction of a flying machine, these
being as follows: 'Make a car of as light material as possible, but
with sufficient strength to support a man in it; provide a pair of wings
about four feet each in length; let them be horizontally expanded and
fastened upon the top edge of each side of the car, with two joints
each, so as to admit of a vertical motion to the wings, which motion may
be effected by a man sitting and working an upright lever in the middle
of the car. Extend in the front of the car a flat surface of silk, which
must be stretched out and kept fixed in a passive state; there must
be the same fixed behind the car; these two surfaces must be perfectly
equal in length and breadth and large enough to cover a sufficient
quantity of air to support the whole weight as nearly in equilibrium as
possible, thus we shall have a great sustaining power in those passive
surfaces and the active wings will propel the car forward.'
A description of how to launch this car is subsequently given: 'It
becomes necessary,' says the theorist, 'that I should give directions
how it may be launched upon the air, which may be done by various means;
perhaps the following method may be found to answer as well as any: Fix
a poll upright in the earth, about twenty feet in height, with two open
collars to admit another poll to slide upwards through them; let there
be a sliding platform made fast upon the top of the sliding poll; place
the car with a man in it upon the platform, then raise the platform to
the height of about thirty feet by means of the sliding poll, let the
sliding poll and platform suddenly fall down, the car will then be
left upon the air, and by its pressing the air a projectile force will
instantly propel the car forward; the man in the car must then strike
the active wings briskly upon the air, which will so increase the
projectile force as to become superior to the force of gravitation, and
if he inclines his weight a little backward, the projectile impulse will
drive the car forward in an ascending direction. When the car is brought
to a sufficient altitude to clear the tops of hills, trees, buildings,
etc., the man, by sitting a little forward on his seat, will then bring
the wings upon a horizontal plane, and by continuing the action of the
wings he will be impelled forward in that direction. To descend, he
must desist from striking the wings, and hold them on a level with their
joints; the car will then gradually come down, and when it is within
five or six feet of the ground the man must instantly strike the wings
downwards, and sit as far back as he can; he will by this means check
the projectile force, and cause the car to alight very gently with a
retrograde motion. The car, when up in the air, may be made to turn
to the right or to the left by forcing out one of the fins, having one
about eighteen inches long placed vertically on each side of the car for
that purpose, or perhaps merely by the man inclining the weight of his
body to one side.'
Having stated how the thing is to be done, Walker is careful to explain
that when it is done there will be in it some practical use, notably in
respect of the conveyance of mails and newspapers, or the saving of
life at sea, or for exploration, etc. It might even reduce the number of
horses kept by man for his use, by means of which a large amount of land
might be set free for the growth of food for human consumption.
At the end of his work Walker admits the idea of steam power for driving
a flying machine in place of simple human exertion, but he, like Cayley,
saw a drawback to this in the weight of the necessary engine. On the
whole, he concluded, navigation of the air by means of engine power
would be mostly confined to the construction of navigable balloons.
As already noted, Walker's work is not over practical, and the foregoing
extract includes the most practical part of it; the rest is a series
of dissertations on bird flight, in which, evidently, the portrait
painter's observations were far less thorough than those of da Vinci or
Borelli. Taken on the whole, Walker was a man with a hobby; he devoted
to it much time and thought, but it remained a hobby, nevertheless. His
observations have proved useful enough to give him a place among the
early students of flight, but a great drawback to his work is the lack
of practical experiment, by means of which alone real advance could
be made; for, as Cayley admitted, theory and practice are very widely
separated in the study of aviation, and the whole history of flight is
a matter of unexpected results arising from scarcely foreseen causes,
together with experiment as patient as daring.
IV. THE MIDDLE NINETEENTH CENTURY
Both Cayley and Walker were theorists, though Cayley supported his
theoretical work with enough of practice to show that he studied along
right lines; a little after his time there came practical men
who brought to being the first machine which actually flew by the
application of power. Before their time, however, mention must be made
of the work of George Pocock of Bristol, who, somewhere about 1840
invented what was described as a 'kite carriage,' a vehicle which
carried a number of persons, and obtained its motive power from a large
kite. It is on record that, in the year 1846 one of these carriages
conveyed sixteen people from Bristol to London. Another device of
Pocock's was what he called a 'buoyant sail,' which was in effect a
man-lifting kite, and by means of which a passenger was actually raised
100 yards from the ground, while the inventor's son scaled a cliff
200 feet in height by means of one of these, 'buoyant sails.' This
constitutes the first definitely recorded experiment in the use of
man-lifting kites. A History of the Charvolant or Kite-carriage,
published in London in 1851, states that 'an experiment of a bold and
very novel character was made upon an extensive down, where a large
wagon with a considerable load was drawn along, whilst this huge machine
at the same time carried an observer aloft in the air, realising almost
the romance of flying.'
Experimenting, two years after the appearance of the 'kite-carriage,'
on the helicopter principle, W. H. Phillips constructed a model machine
which weighed two pounds; this was fitted with revolving fans, driven
by the combustion of charcoal, nitre, and gypsum, producing steam which,
discharging into the air, caused the fans to revolve. The inventor
stated that 'all being arranged, the steam was up in a few seconds, when
the whole apparatus spun around like any top, and mounted into the
air faster than a bird; to what height it ascended I had no means of
ascertaining; the distance travelled was across two fields, where, after
a long search, I found the machine minus the wings, which had been
torn off in contact with the ground.' This could hardly be described as
successful flight, but it was an advance in the construction of machines
on the helicopter principle, and it was the first steam-driven model of
the type which actually flew. The invention, however, was not followed
up.
After Phillips, we come to the great figures of the middle nineteenth
century, W. S. Henson and John Stringfellow. Cayley had shown, in
1809, how success might be attained by developing the idea of the plane
surface so driven as to take advantage of the resistance offered by
the air, and Henson, who as early as 1840 was experimenting with model
gliders and light steam engines, evolved and patented an idea for
something very nearly resembling the monoplane of the early twentieth
century. His patent, No. 9478, of the year 1842 explains the principle
of the machine as follows:--
In order that the description hereafter given be rendered clear, I will
first shortly explain the principle on which the machine is constructed.
If any light and flat or nearly flat article be projected or thrown
edgewise in a slightly inclined position, the same will rise on the
air till the force exerted is expended, when the article so thrown or
projected will descend; and it will readily be conceived that, if the
article so projected or thrown possessed in itself a continuous power or
force equal to that used in throwing or projecting it, the article
would continue to ascend so long as the forward part of the surface was
upwards in respect to the hinder part, and that such article, when the
power was stopped, or when the inclination was reversed, would descend
by gravity aided by the force of the power contained in the article, if
the power be continued, thus imitating the flight of a bird.
Now, the first part of my invention consists of an apparatus so
constructed as to offer a very extended surface or plane of a light yet
strong construction, which will have the same relation to the general
machine which the extended wings of a bird have to the body when a bird
is skimming in the air; but in place of the movement or power for onward
progress being obtained by movement of the extended surface or plane, as
is the case with the wings of birds, I apply suitable paddle-wheels
or other proper mechanical propellers worked by a steam or other
sufficiently light engine, and thus obtain the requisite power for
onward movement to the plane or extended surface; and in order to give
control as to the upward and downward direction of such a machine I
apply a tail to the extended surface which is capable of being inclined
or raised, so that when the power is acting to propel the machine, by
inclining the tail upwards, the resistance offered by the air will
cause the machine to rise on the air; and, on the contrary, when the
inclination of the tail is reversed, the machine will immediately be
propelled downwards, and pass through a plane more or less inclined to
the horizon as the inclination of the tail is greater or less; and in
order to guide the machine as to the lateral direction which it shall
take, I apply a vertical rudder or second tail, and, according as the
same is inclined in one direction or the other, so will be the direction
of the machine.'
The machine in question was very large, and differed very little from
the modern monoplane; the materials were to be spars of bamboo and
hollow wood, with diagonal wire bracing. The surface of the planes was
to amount to 4,500 square feet, and the tail, triangular in form (here
modern practice diverges) was to be 1,500 square feet. The inventor
estimated that there would be a sustaining power of half a pound per
square foot, and the driving power was to be supplied by a steam engine
of 25 to 30 horse-power, driving two six-bladed propellers. Henson was
largely dependent on Stringfellow for many details of his design, more
especially with regard to the construction of the engine.
The publication of the patent attracted a great amount of public
attention, and the illustrations in contemporary journals, representing
the machine flying over the pyramids and the Channel, anticipated fact
by sixty years and more; the scientific world was divided, as it was
up to the actual accomplishment of flight, as to the value of the
invention.
Strongfellow and Henson became associated after the conception of their
design, with an attorney named Colombine, and a Mr Marriott, and
between the four of them a project grew for putting the whole thing on
a commercial basis--Henson and Stringfellow were to supply the idea;
Marriott, knowing a member of Parliament, would be useful in getting a
company incorporated, and Colombine would look after the purely legal
side of the business. Thus an application was made by Mr Roebuck,
Marriott's M.P., for an act of incorporation for 'The Aerial Steam
Transit Company,' Roebuck moving to bring in the bill on the 24th of
March, 1843. The prospectus, calling for funds for the development of
the invention, makes interesting reading at this stage of aeronautical
development; it was as follows:
PROPOSAL.
For subscriptions of sums of L100, in furtherance of an Extraordinary
Invention not at present safe to be developed by securing the necessary
Patents, for which three times the sum advanced, namely, L300, is
conditionally guaranteed for each subscription on February 1, 1844,
in case of the anticipations being realised, with the option of the
subscribers being shareholders for the large amount if so desired, but
not otherwise.
---------An Invention has recently been discovered, which if ultimately
successful will be without parallel even in the age which introduced to
the world the wonderful effects of gas and of steam.
The discovery is of that peculiar nature, so simple in principle yet
so perfect in all the ingredients required for complete and permanent
success, that to promulgate it at present would wholly defeat its
development by the immense competition which would ensue, and the views
of the originator be entirely frustrated.
This work, the result of years of labour and study, presents a wonderful
instance of the adaptation of laws long since proved to the scientific
world combined with established principles so judiciously and carefully
arranged, as to produce a discovery perfect in all its parts and alike
in harmony with the laws of Nature and of science.
The Invention has been subjected to several tests and examinations
and the results are most satisfactory so much so that nothing but the
completion of the undertaking is required to determine its practical
operation, which being once established its utility is undoubted, as it
would be a necessary possession of every empire, and it were hardly too
much to say, of every individual of competent means in the civilised
world.
Its qualities and capabilities are so vast that it were impossible and,
even if possible, unsafe to develop them further, but some idea may
be formed from the fact that as a preliminary measure patents in Great
Britain Ireland, Scotland, the Colonies, France, Belgium, and the
United States, and every other country where protection to the first
discoveries of an Invention is granted, will of necessity be immediately
obtained, and by the time these are perfected, which it is estimated
will be in the month of February, the Invention will be fit for Public
Trial, but until the Patents are sealed any further disclosure would be
most dangerous to the principle on which it is based.
Under these circumstances, it is proposed to raise an immediate sum of
L2,000 in furtherance of the Projector's views, and as some protection
to the parties who may embark in the matter, that this is not a
visionary plan for objects imperfectly considered, Mr Colombine, to whom
the secret has been confided, has allowed his name to be used on the
occasion, and who will if referred to corroborate this statement, and
convince any inquirer of the reasonable prospects of large pecuniary
results following the development of the Invention.
It is, therefore, intended to raise the sum of L2,000 in twenty sums of
L100 each (of which any subscriber may take one or more not exceeding
five in number to be held by any individual) the amount of which is to
be paid into the hands of Mr Colombine as General Manager of the concern
to be by him appropriated in procuring the several Patents and providing
the expenses incidental to the works in progress. For each of which
sums of L100 it is intended and agreed that twelve months after the
1st February next, the several parties subscribing shall receive as an
equivalent for the risk to be run the sum of L300 for each of the sums
of L100 now subscribed, provided when the time arrives the Patents shall
be found to answer the purposes intended.
As full and complete success is alone looked to, no moderate or
imperfect benefit is to be anticipated, but the work, if it once passes
the necessary ordeal, to which inventions of every kind must be first
subject, will then be regarded by every one as the most astonishing
discovery of modern times; no half success can follow, and therefore the
full nature of the risk is immediately ascertained.
The intention is to work and prove the Patent by collective instead of
individual aid as less hazardous at first end more advantageous in the
result for the Inventor, as well as others, by having the interest of
several engaged in aiding one common object--the development of a
Great Plan. The failure is not feared, yet as perfect success might, by
possibility, not ensue, it is necessary to provide for that result,
and the parties concerned make it a condition that no return of
the subscribed money shall be required, if the Patents shall by any
unforeseen circumstances not be capable of being worked at all; against
which, the first application of the money subscribed, that of securing
the Patents, affords a reasonable security, as no one without solid
grounds would think of such an expenditure.
It is perfectly needless to state that no risk or responsibility of any
kind can arise beyond the payment of the sum to be subscribed under any
circumstances whatever.
As soon as the Patents shall be perfected and proved it is contemplated,
so far as may be found practicable, to further the great object in view
a Company shall be formed but respecting which it is unnecessary to
state further details, than that a preference will be given to all those
persons who now subscribe, and to whom shares shall be appropriated
according to the larger amount (being three times the sum to be paid by
each person) contemplated to be returned as soon as the success of the
Invention shall have been established, at their option, or the money
paid, whereby the Subscriber will have the means of either withdrawing
with a large pecuniary benefit, or by continuing his interest in the
concern lay the foundation for participating in the immense benefit
which must follow the success of the plan.
It is not pretended to conceal that the project is a speculation--all
parties believe that perfect success, and thence incalculable advantage
of every kind, will follow to every individual joining in this great
undertaking; but the Gentlemen engaged in it wish that no concealment
of the consequences, perfect success, or possible failure, should in the
slightest degree be inferred. They believe this will prove the germ of a
mighty work, and in that belief call for the operation of others with no
visionary object, but a legitimate one before them, to attain that point
where perfect success will be secured from their combined exertions.
All applications to be made to D. E. Colombine, Esquire, 8 Carlton
Chambers, Regent Street.
The applications did not materialise, as was only to be expected in view
of the vagueness of the proposals. Colombine did some advertising, and
Mr Roebuck expressed himself as unwilling to proceed further in the
venture. Henson experimented with models to a certain extent, while
Stringfellow looked for funds for the construction of a full-sized
monoplane. In November of 1843 he suggested that he and Henson should
construct a large model out of their own funds. On Henson's suggestion
Colombine and Marriott were bought out as regards the original patent,
and Stringfellow and Henson entered into an agreement and set to work.
Their work is briefly described in a little pamphlet by F. J.
Stringfellow, entitled A few Remarks on what has been done with
screw-propelled Aero-plane Machines from 1809 to 1892. The author writes
with regard to the work that his father and Henson undertook:--
'They commenced the construction of a small model operated by a spring,
and laid down the larger model 20 ft. from tip to tip of planes, 3 1/2
ft. wide, giving 70 ft. of sustaining surface, about 10 more in the
tail. The making of this model required great consideration; various
supports for the wings were tried, so as to combine lightness with
firmness, strength and rigidity.
'The planes were staid from three sets of fish-shaped masts, and rigged
square and firm by flat steel rigging. The engine and boiler were put in
the car to drive two screw-propellers, right and left-handed, 3 ft. in
diameter, with four blades each, occupying three-quarters of the area
of the circumference, set at an angle of 60 degrees. A considerable time
was spent in perfecting the motive power. Compressed air was tried and
abandoned. Tappets, cams, and eccentrics were all tried, to work the
slide valve, to obtain the best results. The piston rod of engine passed
through both ends of the cylinder, and with long connecting rods worked
direct on the crank of the propellers. From memorandum of experiments
still preserved the following is a copy of one: June, 27th, 1845, water
50 ozs., spirit 10 ozs., lamp lit 8.45, gauge moves 8.46, engine started
8.48 (100 lb. pressure), engine stopped 8.57, worked 9 minutes, 2,288
revolutions, average 254 per minute. No priming, 40 ozs. water consumed,
propulsion (thrust of propellers), 5 lbs. 4 1/2 ozs. at commencement,
steady, 4 lbs. 1/2 oz., 57 revolutions to 1 oz. water, steam cut off
one-third from beginning.
'The diameter of cylinder of engine was 1 1/2 inch, length of stroke 3
inches.
'In the meantime an engine was also made for the smaller model, and a
wing action tried, but with poor results. The time was mostly devoted to
the larger model, and in 1847 a tent was erected on Bala Down, about two
miles from Chard, and the model taken up one night by the workmen. The
experiments were not so favourable as was expected. The machine could
not support itself for any distance, but, when launched off, gradually
descended, although the power and surface should have been ample;
indeed, according to latest calculations, the thrust should have carried
more than three times the weight, for there was a thrust of 5 lbs. from
the propellers, and a surface of over 70 square feet to sustain under 30
lbs., but necessary speed was lacking.'
Stringfellow himself explained the failure as follows:--
'There stood our aerial protegee in all her purity--too delicate, too
fragile, too beautiful for this rough world; at least those were
my ideas at the time, but little did I think how soon it was to be
realised. I soon found, before I had time to introduce the spark, a
drooping in the wings, a flagging in all the parts. In less than ten
minutes the machine was saturated with wet from a deposit of dew, so
that anything like a trial was impossible by night. I did not consider
we could get the silk tight and rigid enough. Indeed, the framework
altogether was too weak. The steam-engine was the best part. Our want of
success was not for want of power or sustaining surface, but for want of
proper adaptation of the means to the end of the various parts.'
Henson, who had spent a considerable amount of money in these
experimental constructions, consoled himself for failure by venturing
into matrimony; in 1849 he went to America, leaving Stringfellow to
continue experimenting alone. From 1846 to 1848 Stringfellow worked on
what is really an epoch-making item in the history of aeronautics--the
first engine-driven aeroplane which actually flew. The machine in
question had a 10 foot span, and was 2 ft. across in the widest part of
the wing; the length of tail was 3 ft. 6 ins., and the span of tail in
the widest part 22 ins., the total sustaining area being about 14
sq. ft. The motive power consisted of an engine with a cylinder of
three-quarter inch diameter and a two-inch stroke; between this and
the crank shaft was a bevelled gear giving three revolutions of the
propellers to every stroke of the engine; the propellers, right and left
screw, were four-bladed and 16 inches in diameter. The total weight of
the model with engine was 8 lbs. Its successful flight is ascribed to
the fact that Stringfellow curved the wings, giving them rigid front
edges and flexible trailing edges, as suggested long before both by Da
Vinci and Borelli, but never before put into practice.
Mr F. J. Stringfellow, in the pamphlet quoted above, gives the best
account of the flight of this model: 'My father had constructed another
small model which was finished early in 1848, and having the loan of a
long room in a disused lace factory, early in June the small model was
moved there for experiments. The room was about 22 yards long and
from 10 to 12 ft. high.... The inclined wire for starting the machine
occupied less than half the length of the room and left space at the end
for the machine to clear the floor. In the first experiment the tail was
set at too high an angle, and the machine rose too rapidly on leaving
the wire. After going a few yards it slid back as if coming down an
inclined plane, at such an angle that the point of the tail struck the
ground and was broken. The tail was repaired and set at a smaller angle.
The steam was again got up, and the machine started down the wire, and,
upon reaching the point of self-detachment, it gradually rose until
it reached the farther end of the room, striking a hole in the canvas
placed to stop it. In experiments the machine flew well, when rising as
much as one in seven. The late Rev. J. Riste, Esq., lace manufacturer,
Northcote Spicer, Esq., J. Toms, Esq., and others witnessed experiments.
Mr Marriatt, late of the San Francisco News Letter brought down from
London Mr Ellis, the then lessee of Cremorne Gardens, Mr Partridge, and
Lieutenant Gale, the aeronaut, to witness experiments. Mr Ellis offered
to construct a covered way at Cremorne for experiments. Mr Stringfellow
repaired to Cremorne, but not much better accommodations than he had
at home were provided, owing to unfulfilled engagement as to room.
Mr Stringfellow was preparing for departure when a party of gentlemen
unconnected with the Gardens begged to see an experiment, and finding
them able to appreciate his endeavours, he got up steam and started the
model down the wire. When it arrived at the spot where it should leave
the wire it appeared to meet with some obstruction, and threatened to
come to the ground, but it soon recovered itself and darted off in
as fair a flight as it was possible to make at a distance of about 40
yards, where it was stopped by the canvas.
'Having now demonstrated the practicability of making a steam-engine
fly, and finding nothing but a pecuniary loss and little honour,
this experimenter rested for a long time, satisfied with what he had
effected. The subject, however, had to him special charms, and he still
contemplated the renewal of his experiments.'
It appears that Stringfellow's interest did not revive sufficiently
for the continuance of the experiments until the founding of the
Aeronautical Society of Great Britain in 1866. Wenham's paper on Aerial
Locomotion read at the first meeting of the Society, which was held at
the Society of Arts under the Presidency of the Duke of Argyll, was
the means of bringing Stringfellow back into the field. It was Wenham's
suggestion, in the first place, that monoplane design should be
abandoned for the superposition of planes; acting on this suggestion
Stringfellow constructed a model triplane, and also designed a steam
engine of slightly over one horse-power, and a one horse-power copper
boiler and fire box which, although capable of sustaining a pressure of
500 lbs. to the square inch, weighed only about 40 lbs.
Both the engine and the triplane model were exhibited at the first
Aeronautical Exhibition held at the Crystal Palace in 1868. The triplane
had a supporting surface of 28 sq. ft.; inclusive of engine, boiler,
fuel, and water its total weight was under 12 lbs. The engine worked two
21 in. propellers at 600 revolutions per minute, and developed 100 lbs.
steam pressure in five minutes, yielding one-third horse-power. Since
no free flight was allowed in the Exhibition, owing to danger from fire,
the triplane was suspended from a wire in the nave of the building,
and it was noted that, when running along the wire, the model made a
perceptible lift.
A prize of L100 was awarded to the steam engine as the lightest steam
engine in proportion to its power. The engine and model together may
be reckoned as Stringfellow's best achievement. He used his L100 in
preparation for further experiments, but he was now an old man, and
his work was practically done. Both the triplane and the engine were
eventually bought for the Washington Museum; Stringfellow's earlier
models, together with those constructed by him in conjunction with
Henson, remain in this country in the Victoria and Albert Museum.
John Stringfellow died on December 13th, 1883. His place in the history
of aeronautics is at least equal to that of Cayley, and it may be
said that he laid the foundation of such work as was subsequently
accomplished by Maxim, Langley, and their fellows. It was the coming of
the internal combustion engine that rendered flight practicable, and had
this prime mover been available in John Stringfellow's day the Wright
brothers' achievement might have been antedated by half a century.
V. WENHAM, LE BRIS, AND SOME OTHERS
There are few outstanding events in the development of aeronautics
between Stringfellow's final achievement and the work of such men as
Lilienthal, Pilcher, Montgomery, and their kind; in spite of this, the
later middle decades of the nineteenth century witnessed a considerable
amount of spade work both in England and in France, the two countries
which led in the way in aeronautical development until Lilienthal gave
honour to Germany, and Langley and Montgomery paved the way for the
Wright Brothers in America.
Two abortive attempts characterised the sixties of last century in
France. As regards the first of these, it was carried out by three men,
Nadar, Ponton d'Amecourt, and De la Landelle, who conceived the idea
of a full-sized helicopter machine. D'Amecourt exhibited a steam model,
constructed in 1865, at the Aeronautical Society's Exhibition in 1868.
The engine was aluminium with cylinders of bronze, driving two screws
placed one above the other and rotating in Opposite directions, but the
power was not sufficient to lift the model. De la Landelle's principal
achievement consisted in the publication in 1863 of a book entitled
Aviation which has a certain historical value; he got out several
designs for large machines on the helicopter principle, but did little
more until the three combined in the attempt to raise funds for the
construction of their full-sized machine. Since the funds were not
forthcoming, Nadar took to ballooning as the means of raising money;
apparently he found this substitute for real flight sufficiently
interesting to divert him from the study of the helicopter principle,
for the experiment went no further.
The other experimenter of this period, one Count d'Esterno, took out a
patent in 1864 for a soaring machine which allowed for alteration of
the angle of incidence of the wings in the manner that was subsequently
carried out by the Wright Brothers. It was not until 1883 that any
attempt was made to put this patent to practical use, and, as the
inventor died while it was under construction, it was never completed.
D'Esterno was also responsible for the production of a work entitled
Du Vol des Oiseaux, which is a very remarkable study of the flight of
birds.
Mention has already been made of the founding of the Aeronautical
Society of Great Britain, which, since 1918 has been the Royal
Aeronautical Society. 1866 witnessed the first meeting of the Society
under the Presidency of the Duke of Argyll, when in June, at the Society
of Arts, Francis Herbert Wenham read his now classic paper Aerial
Locomotion. Certain quotations from this will show how clearly Wenham
had thought out the problems connected with flight.
'The first subject for consideration is the proportion of surface to
weight, and their combined effect in descending perpendicularly through
the atmosphere. The datum is here based upon the consideration of
safety, for it may sometimes be needful for a living being to drop
passively, without muscular effort. One square foot of sustaining
surface for every pound of the total weight will be sufficient for
security.
'According to Smeaton's table of atmospheric resistances, to produce
a force of one pound on a square foot, the wind must move against the
plane (or which is the same thing, the plane against the wind), at the
rate of twenty-two feet per second, or 1,320 feet per minute, equal to
fifteen miles per hour. The resistance of the air will now balance the
weight on the descending surface, and, consequently, it cannot exceed
that speed. Now, twenty-two feet per second is the velocity acquired at
the end of a fall of eight feet--a height from which a well-knit man or
animal may leap down without much risk of injury. Therefore, if a man
with parachute weigh together 143 lbs., spreading the same number of
square feet of surface contained in a circle fourteen and a half feet
in diameter, he will descend at perhaps an unpleasant velocity, but with
safety to life and limb.
'It is a remarkable fact how this proportion of wing-surface to weight
extends throughout a great variety of the flying portion of the
animal kingdom, even down to hornets, bees, and other insects. In some
instances, however, as in the gallinaceous tribe, including pheasants,
this area is somewhat exceeded, but they are known to be very poor
fliers. Residing as they do chiefly on the ground, their wings are
only required for short distances, or for raising them or easing their
descent from their roosting-places in forest trees, the shortness
of their wings preventing them from taking extended flights. The
wing-surface of the common swallow is rather more than in the ratio of
two square feet per pound, but having also great length of pinion, it is
both swift and enduring in its flight. When on a rapid course this bird
is in the habit of furling its wings into a narrow compass. The greater
extent of surface is probably needful for the continual variations of
speed and instant stoppages for obtaining its insect food.
'On the other hand, there are some birds, particularly of the duck
tribe, whose wing-surface but little exceeds half a square foot,
or seventy-two inches per pound, yet they may be classed among the
strongest and swiftest of fliers. A weight of one pound, suspended
from an area of this extent, would acquire a velocity due to a fall of
sixteen feet--a height sufficient for the destruction or injury of most
animals. But when the plane is urged forward horizontally, in a manner
analogous to the wings of a bird during flight, the sustaining power is
greatly influenced by the form and arrangement of the surface.
'In the case of perpendicular descent, as a parachute, the sustaining
effect will be much the same, whatever the figure of the outline of the
superficies may be, and a circle perhaps affords the best resistance of
any. Take, for example, a circle of twenty square feet (as possessed
by the pelican) loaded with as many pounds. This, as just stated, will
limit the rate of perpendicular descent to 1,320 feet per minute. But
instead of a circle sixty-one inches in diameter, if the area is bounded
by a parallelogram ten feet long by two feet broad, and whilst at
perfect freedom to descend perpendicularly, let a force be applied
exactly in a horizontal direction, so as to carry it edgeways, with the
long side foremost, at a forward speed of thirty miles per hour--just
double that of its passive descent: the rate of fall under these
conditions will be decreased most remarkably, probably to less than
one-fifteenth part, or eighty-eight feet per minute, or one mile per
hour.'
And again: 'It has before been shown how utterly inadequate the mere
perpendicular impulse of a plane is found to be in supporting a weight,
when there is no horizontal motion at the time. There is no material
weight of air to be acted upon, and it yields to the slightest force,
however great the velocity of impulse may be. On the other hand, suppose
that a large bird, in full flight, can make forty miles per hour, or
3,520 feet per minute, and performs one stroke per second. Now, during
every fractional portion of that stroke, the wing is acting upon and
obtaining an impulse from a fresh and undisturbed body of air; and if
the vibration of the wing is limited to an arc of two feet, this by no
means represents the small force of action that would be obtained when
in a stationary position, for the impulse is secured upon a stratum of
fifty-eight feet in length of air at each stroke. So that the conditions
of weight of air for obtaining support equally well apply to weight of
air and its reaction in producing forward impulse.
'So necessary is the acquirement of this horizontal speed, even in
commencing flight, that most heavy birds, when possible, rise against
the wind, and even run at the top of their speed to make their wings
available, as in the example of the eagle, mentioned at the commencement
of this paper. It is stated that the Arabs, on horseback, can approach
near enough to spear these birds, when on the plain, before they are
able to rise; their habit is to perch on an eminence, where possible.
'The tail of a bird is not necessary for flight. A pigeon can fly
perfectly with this appendage cut short off; it probably performs an
important function in steering, for it is to be remarked, that most
birds that have either to pursue or evade pursuit are amply provided
with this organ.
'The foregoing reasoning is based upon facts, which tend to show that
the flight of the largest and heaviest of all birds is really performed
with but a small amount of force, and that man is endowed with
sufficient muscular power to enable him also to take individual and
extended flights, and that success is probably only involved in a
question of suitable mechanical adaptations. But if the wings are to be
modelled in imitation of natural examples, but very little consideration
will serve to demonstrate its utter impracticability when applied in
these forms.'
Thus Wenham, one of the best theorists of his age. The Society with
which this paper connects his name has done work, between that time and
the present, of which the importance cannot be overestimated, and has
been of the greatest value in the development of aeronautics, both in
theory and experiment. The objects of the Society are to give a stronger
impulse to the scientific study of aerial navigation, to promote the
intercourse of those interested in the subject at home and abroad, and
to give advice and instruction to those who study the principles upon
which aeronautical science is based. From the date of its foundation the
Society has given special study to dynamic flight, putting this before
ballooning. Its library, its bureau of advice and information, and its
meetings, all assist in forwarding the study of aeronautics, and its
twenty-three early Annual Reports are of considerable value, containing
as they do a large amount of useful information on aeronautical
subjects, and forming practically the basis of aeronautical science.
Ante to Wenham, Stringfellow and the French experimenters already noted,
by some years, was Le Bris, a French sea captain, who appears to have
required only a thorough scientific training to have rendered him of
equal moment in the history of gliding flight with Lilienthal himself.
Le Bris, it appears, watched the albatross and deduced, from the manner
in which it supported itself in the air, that plane surfaces could
be constructed and arranged to support a man in like manner. Octave
Chanute, himself a leading exponent of gliding, gives the best
description of Le Bris's experiments in a work, Progress in Flying
Machines, which, although published as recently as I 1894, is already
rare. Chanute draws from a still rarer book, namely, De la Landelle's
work published in 1884. Le Bris himself, quoted by De la Landelle as
speaking of his first visioning of human flight, describes how he killed
an albatross, and then--'I took the wing of the albatross and exposed
it to the breeze; and lo! in spite of me it drew forward into the wind;
notwithstanding my resistance it tended to rise. Thus I had discovered
the secret of the bird! I comprehended the whole mystery of flight.'
This apparently took place while at sea; later on Le Bris, returning to
France, designed and constructed an artificial albatross of sufficient
size to bear his own weight. The fact that he followed the bird outline
as closely as he did attests his lack of scientific training for his
task, while at the same time the success of the experiment was proof of
his genius. The body of his artificial bird, boat-shaped, was 13 1/2 ft.
in length, with a breadth of 4 ft. at the widest part. The material
was cloth stretched over a wooden framework; in front was a small mast
rigged after the manner of a ship's masts to which were attached poles
and cords with which Le Bris intended to work the wings. Each wing was
23 ft. in length, giving a total supporting surface of nearly 220 sq.
ft.; the weight of the whole apparatus was only 92 pounds. For steering,
both vertical and horizontal, a hinged tail was provided, and the
leading edge of each wing was made flexible. In construction throughout,
and especially in that of the wings, Le Bris adhered as closely as
possible to the original albatross.
He designed an ingenious kind of mechanism which he termed 'Rotules,'
which by means of two levers gave a rotary motion to the front edge of
the wings, and also permitted of their adjustment to various angles.
The inventor's idea was to stand upright in the body of the contrivance,
working the levers and cords with his hands, and with his feet on
a pedal by means of which the steering tail was to be worked. He
anticipated that, given a strong wind, he could rise into the air after
the manner of an albatross, without any need for flapping his wings, and
the account of his first experiment forms one of the most interesting
incidents in the history of flight. It is related in full in Chanute's
work, from which the present account is summarised.
Le Bris made his first experiment on a main road near Douarnenez, at
Trefeuntec. From his observation of the albatross Le Bris concluded
that it was necessary to get some initial velocity in order to make the
machine rise; consequently on a Sunday morning, with a breeze of about
12 miles an hour blowing down the road, he had his albatross placed on a
cart and set off, with a peasant driver, against the wind. At the outset
the machine was fastened to the cart by a rope running through the rails
on which the machine rested, and secured by a slip knot on Le Bris's own
wrist, so that only a jerk on his part was necessary to loosen the rope
and set the machine free. On each side walked an assistant holding the
wings, and when a turn of the road brought the machine full into the
wind these men were instructed to let go, while the driver increased the
pace from a walk to a trot. Le Bris, by pressure on the levers of the
machine, raised the front edges of his wings slightly; they took the
wind almost instantly to such an extent that the horse, relieved of a
great part of the weight he had been drawing, turned his trot into a
gallop. Le Bris gave the jerk of the rope that should have unfastened
the slip knot, but a concealed nail on the cart caught the rope, so that
it failed to run. The lift of the machine was such, however, that it
relieved the horse of very nearly the weight of the cart and driver, as
well as that of Le Bris and his machine, and in the end the rails of the
cart gave way. Le Bris rose in the air, the machine maintaining perfect
balance and rising to a height of nearly 300 ft., the total length of
the glide being upwards of an eighth of a mile. But at the last moment
the rope which had originally fastened the machine to the cart got wound
round the driver's body, so that this unfortunate dangled in the air
under Le Bris and probably assisted in maintaining the balance of the
artificial albatross. Le Bris, congratulating himself on his success,
was prepared to enjoy just as long a time in the air as the pressure of
the wind would permit, but the howls of the unfortunate driver at the
end of the rope beneath him dispelled his dreams; by working his levers
he altered the angle of the front wing edges so skilfully as to make a
very successful landing indeed for the driver, who, entirely uninjured,
disentangled himself from the rope as soon as he touched the ground, and
ran off to retrieve his horse and cart.
Apparently his release made a difference in the centre of gravity, for
Le Bris could not manipulate his levers for further ascent; by skilful
manipulation he retarded the descent sufficiently to escape injury to
himself; the machine descended at an angle, so that one wing, striking
the ground in front of the other, received a certain amount of damage.
It may have been on account of the reluctance of this same or another
driver that Le Bris chose a different method of launching himself in
making a second experiment with his albatross. He chose the edge of a
quarry which had been excavated in a depression of the ground; here he
assembled his apparatus at the bottom of the quarry, and by means of a
rope was hoisted to a height of nearly 100 ft. from the quarry bottom,
this rope being attached to a mast which he had erected upon the edge
of the depression in which the quarry was situated. Thus hoisted, the
albatross was swung to face a strong breeze that blew inland, and Le
Bris manipulated his levers to give the front edges of his wings a
downward angle, so that only the top surfaces should take the wing
pressure. Having got his balance, he obtained a lifting angle of
incidence on the wings by means of his levers, and released the hook
that secured the machine, gliding off over the quarry. On the glide he
met with the inevitable upward current of air that the quarry and the
depression in which it was situated caused; this current upset the
balance of the machine and flung it to the bottom of the quarry,
breaking it to fragments. Le Bris, apparently as intrepid as ingenious,
gripped the mast from which his levers were worked, and, springing
upward as the machine touched earth, escaped with no more damage than a
broken leg. But for the rebound of the levers he would have escaped even
this.
The interest of these experiments is enhanced by the fact that Le Bris
was a seafaring man who conducted them from love of the science which
had fired his imagination, and in so doing exhausted his own small
means. It was in 1855 that he made these initial attempts, and
twelve years passed before his persistence was rewarded by a public
subscription made at Brest for the purpose of enabling him to continue
his experiments. He built a second albatross, and on the advice of his
friends ballasted it for flight instead of travelling in it himself. It
was not so successful as the first, probably owing to the lack of human
control while in flight; on one of the trials a height of 150 ft. was
attained, the glider being secured by a thin rope and held so as to face
into the wind. A glide of nearly an eighth of a mile was made with the
rope hanging slack, and, at the end of this distance, a rise in the
ground modified the force of the wind, whereupon the machine settled
down without damage. A further trial in a gusty wind resulted in the
complete destruction of this second machine; Le Bris had no more
funds, no further subscriptions were likely to materialise, and so
the experiments of this first exponent of the art of gliding (save
for Besnier and his kind) came to an end. They constituted a notable
achievement, and undoubtedly Le Bris deserves a better place than has
been accorded him in the ranks of the early experimenters.
Contemporary with him was Charles Spencer, the first man to practice
gliding in England. His apparatus consisted of a pair of wings with a
total area of 30 sq. ft., to which a tail and body were attached. The
weight of this apparatus was some 24 lbs., and, launching himself on
it from a small eminence, as was done later by Lilienthal in his
experiments, the inventor made flights of over 120 feet. The glider in
question was exhibited at the Aeronautical Exhibition of 1868.
VI. THE AGE OF THE GIANTS
Until the Wright Brothers definitely solved the problem of flight and
virtually gave the aeroplane its present place in aeronautics, there
were three definite schools of experiment. The first of these was
that which sought to imitate nature by means of the ornithopter or
flapping-wing machines directly imitative of bird flight; the second
school was that which believed in the helicopter or lifting screw; the
third and eventually successful school is that which followed up the
principle enunciated by Cayley, that of opposing a plane surface to the
resistance of the air by supplying suitable motive power to drive it at
the requisite angle for support.
Engineering problems generally go to prove that too close an imitation
of nature in her forms of recipro-cating motion is not advantageous; it
is impossible to copy the minutiae of a bird's wing effectively, and the
bird in flight depends on the tiniest details of its feathers just as
much as on the general principle on which the whole wing is constructed.
Bird flight, however, has attracted many experimenters, including even
Lilienthal; among others may be mentioned F. W. Brearey, who invented
what he called the 'Pectoral cord,' which stored energy on each upstroke
of the artificial wing; E. P. Frost; Major R. Moore, and especially
Hureau de Villeneuve, a most enthusiastic student of this form of
flight, who began his experiments about 1865, and altogether designed
and made nearly 300 artificial birds, one of his later constructions
was a machine in bird form with a wing span of about 50 ft.; the
motive power for this was supplied by steam from a boiler which, being
stationary on the ground, was connected by a length of hose to the
machine. De Villeneuve, turning on steam for his first trial, obtained
sufficient power to make the wings beat very forcibly; with the inventor
on the machine the latter rose several feet into the air, whereupon de
Villeneuve grew nervous and turned off the steam supply. The machine
fell to the earth, breaking one of its wings, and it does not appear
that de Villeneuve troubled to reconstruct it. This experiment remains
as the greatest success yet achieved by any machine constructed on the
ornithopter principle.
It may be that, as forecasted by the prophet Wells, the flapping-wing
machine will yet come to its own and compete with the aeroplane in
efficiency. Against this, however, are the practical advantages of
the rotary mechanism of the aeroplane propeller as compared with the
movement of a bird's wing, which, according to Marey, moves in a figure
of eight. The force derived from a propeller is of necessity continual,
while it is equally obvious that that derived from a flapping movement
is intermittent, and, in the recovery of a wing after completion of one
stroke for the next, there is necessarily a certain cessation, if not
loss, of power.
The matter of experiment along any lines in connection with aviation is
primarily one of hard cash. Throughout the whole history of flight up to
the outbreak of the European war development has been handicapped on
the score of finance, and, since the arrival of the aeroplane, both
ornithopter and helicopter schools have been handicapped by this
consideration. Thus serious study of the efficiency of wings in
imitation of those of the living bird has not been carried to a point
that might win success for this method of propulsion. Even Wilbur Wright
studied this subject and propounded certain theories, while a later and
possibly more scientific student, F. W. Lanchester, has also contributed
empirical conclusions. Another and earlier student was Lawrence
Hargrave, who made a wing-propelled model which achieved successful
flight, and in 1885 was exhibited before the Royal Society of New South
Wales. Hargrave called the principle on which his propeller worked that
of a 'Trochoided plane'; it was, in effect, similar to the feathering of
an oar.
Hargrave, to diverge for a brief while from the machine to the man,
was one who, although he achieved nothing worthy of special remark,
contributed a great deal of painstaking work to the science of flight.
He made a series of experiments with man-lifting kites in addition to
making a study of flapping-wing flight. It cannot be said that he set
forth any new principle; his work was mainly imitative, but at the same
time by developing ideas originated in great measure by others he helped
toward the solution of the problem.
Attempts at flight on the helicopter principle consist in the work of De
la Landelle and others already mentioned. The possibility of flight by
this method is modified by a very definite disadvantage of which lovers
of the helicopter seem to take little account. It is always claimed for
a machine of this type that it possesses great advantages both in rising
and in landing, since, if it were effective, it would obviously be able
to rise from and alight on any ground capable of containing its own
bulk; a further advantage claimed is that the helicopter would be able
to remain stationary in the air, maintaining itself in any position by
the vertical lift of its propeller.
These potential assets do not take into consideration the fact that
efficiency is required not only in rising, landing, and remaining
stationary in the air, but also in actual flight. It must be evident
that if a certain amount of the motive force is used in maintaining the
machine off the ground, that amount of force is missing from the total
of horizontal driving power. Again, it is often assumed by advocates of
this form of flight that the rapidity of climb of the helicopter would
be far greater than that of the driven plane; this view overlooks the
fact that the maintenance of aerodynamic support would claim the greater
part of the engine-power; the rate of ascent would be governed by the
amount of power that could be developed surplus to that required for
maintenance.
This is best explained by actual figures: assuming that a propeller 15
ft. in diameter is used, almost 50 horse-power would be required to
get an upward lift of 1,000 pounds; this amount of horse-power would be
continually absorbed in maintaining the machine in the air at any given
level; for actual lift from one level to another at a speed of eleven
feet per second a further 20 horse-power would be required, which means
that 70 horse-power must be constantly provided for; this absorption
of power in the mere maintenance of aero-dynamic support is a permanent
drawback.
The attraction of the helicopter lies, probably, in the ease with which
flight is demonstrated by means of models constructed on this principle,
but one truism with regard to the principles of flight is that the
problems change remarkably, and often unexpectedly, with the size of
the machine constructed for experiment. Berriman, in a brief but very
interesting manual entitled Principles of Flight, assumed that 'there is
a significant dimension of which the effective area is an expression
of the second power, while the weight became an expression of the third
power. Then once again we have the two-thirds power law militating
against the successful construction of large helicopters, on the ground
that the essential weight increases disproportionately fast to the
effective area. From a consideration of the structural features of
propellers it is evident that this particular relationship does not
apply in practice, but it seems reasonable that some such governing
factor should exist as an explanation of the apparent failure of all
full-sized machines that have been constructed. Among models there is
nothing more strikingly successful than the toy helicopter, in which the
essential weight is so small compared with the effective area.'
De la Landelle's work, already mentioned, was carried on a few years
later by another Frenchman, Castel, who constructed a machine with eight
propellers arranged in two fours and driven by a compressed air motor or
engine. The model with which Castel experimented had a total weight of
only 49 lbs.; it rose in the air and smashed itself by driving against
a wall, and the inventor does not seem to have proceeded further.
Contemporary with Castel was Professor Forlanini, whose design was for
a machine very similar to de la Landelle's, with two superposed screws.
This machine ranks as the second on the helicopter principle to achieve
flight; it remained in the air for no less than the third of a minute in
one of its trials.
Later experimenters in this direction were Kress, a German; Professor
Wellner, an Austrian; and W. R. Kimball, an American. Kress, like most
Germans, set to the development of an idea which others had originated;
he followed de la Landelle and Forlanini by fitting two superposed
propellers revolving in opposite directions, and with this machine he
achieved good results as regards horse-power to weight; Kimball, it
appears, did not get beyond the rubber-driven model stage, and any
success he may have achieved was modified by the theory enunciated by
Berriman and quoted above.
Comparing these two schools of thought, the helicopter and bird-flight
schools, it appears that the latter has the greater chance of eventual
success--that is, if either should ever come into competition with the
aeroplane as effective means of flight. So far, the aeroplane holds
the field, but the whole science of flight is so new and so full of
unexpected developments that this is no reason for assuming that other
means may not give equal effect, when money and brains are diverted from
the driven plane to a closer imitation of natural flight.
Reverting from non-success to success, from consideration of the two
methods mentioned above to the direction in which practical flight
has been achieved, it is to be noted that between the time of Le
Bris, Stringfellow, and their contemporaries, and the nineties of last
century, there was much plodding work carried out with little visible
result, more especially so far as English students were concerned. Among
the incidents of those years is one of the most pathetic tragedies in
the whole history of aviation, that of Alphonse Penaud, who, in his
thirty years of life, condensed the experience of his predecessors and
combined it with his own genius to state in a published patent what
the aeroplane of to-day should be. Consider the following abstract of
Penaud's design as published in his patent of 1876, and comparison of
this with the aeroplane that now exists will show very few divergences
except for those forced on the inventor by the fact that the internal
combustion engine had not then developed. The double surfaced planes
were to be built with wooden ribs and arranged with a slight dihedral
angle; there was to be a large aspect ratio and the wings were cambered
as in Stringfellow's later models. Provision was made for warping the
wings while in flight, and the trailing edges were so designed as to
be capable of upward twist while the machine was in the air. The planes
were to be placed above the car, and provision was even made for a glass
wind-screen to give protection to the pilot during flight. Steering was
to be accomplished by means of lateral and vertical planes forming
a tail; these controlled by a single lever corresponding to the 'joy
stick' of the present day plane.
Penaud conceived this machine as driven by two propellers; alternatively
these could be driven by petrol or steam-fed motor, and the centre of
gravity of the machine while in flight was in the front fifth of the
wings. Penaud estimated from 20 to 30 horse-power sufficient to drive
this machine, weighing with pilot and passenger 2,600 lbs., through the
air at a speed of 60 miles an hour, with the wings set at an angle
of incidence of two degrees. So complete was the design that it even
included instruments, consisting of an aneroid, pressure indicator, an
anemometer, a compass, and a level. There, with few alterations, is the
aeroplane as we know it--and Penaud was twenty-seven when his patent was
published.
For three years longer he worked, experimenting with models,
contributing essays and other valuable data to French papers on the
subject of aeronautics. His gains were ill health, poverty, and neglect,
and at the age of thirty a pistol shot put an end to what had promised
to be one of the most brilliant careers in all the history of flight.
Two years before the publication of Penaud's patent Thomas Moy
experimented at the Crystal Palace with a twin-propelled aeroplane,
steam driven, which seems to have failed mainly because the internal
combustion engine had not yet come to give sufficient power for weight.
Moy anchored his machine to a pole running on a prepared circular track;
his engine weighed 80 lbs. and, developing only three horse-power, gave
him a speed of 12 miles an hour. He himself estimated that the machine
would not rise until he could get a speed of 35 miles an hour, and his
estimate was correct. Two six-bladed propellers were placed side by side
between the two main planes of the machine, which was supported on a
triangular wheeled undercarriage and steered by fairly conventional tail
planes. Moy realised that he could not get sufficient power to achieve
flight, but he went on experimenting in various directions, and left
much data concerning his experiments which has not yet been deemed
worthy of publication, but which still contains a mass of information
that is of practical utility, embodying as it does a vast amount of
painstaking work.
Penaud and Moy were followed by Goupil, a Frenchman, who, in place of
attempting to fit a motor to an aeroplane, experimented by making the
wind his motor. He anchored his machine to the ground, allowing it two
feet of lift, and merely waited for a wind to come along and lift it.
The machine was stream lined, and the wings, curving as in the early
German patterns of war aeroplanes, gave a total lifting surface of about
290 sq. ft. Anchored to the ground and facing a wind of 19 feet per
second, Goupil's machine lifted its own weight and that of two men as
well to the limit of its anchorage. Although this took place as late
as 1883 the inventor went no further in practical work. He published a
book, however, entitled La Locomotion Aerienne, which is still of great
importance, more especially on the subject of inherent stability.
In 1884 came the first patents of Horatio Phillips, whose work lay
mainly in the direction of investigation into the curvature of plane
surfaces, with a view to obtaining the greatest amount of support.
Phillips was one of the first to treat the problem of curvature of
planes as a matter for scientific experiment, and, great as has been the
development of the driven plane in the 36 years that have passed since
he began, there is still room for investigation into the subject which
he studied so persistently and with such valuable result.
At this point it may be noted that, with the solitary exception of
Le Bris, practically every student of flight had so far set about
constructing the means of launching humanity into the air without any
attempt at ascertaining the nature and peculiarities of the sustaining
medium. The attitude of experimenters in general might be compared to
that of a man who from boyhood had grown up away from open water, and,
at the first sight of an expanse of water, set to work to construct a
boat with a vague idea that, since wood would float, only sufficient
power was required to make him an efficient navigator. Accident,
perhaps, in the shape of lack of means of procuring driving power, drove
Le Bris to the form of experiment which he actually carried out; it
remained for the later years of the nineteenth century to produce men
who were content to ascertain the nature of the support the air would
afford before attempting to drive themselves through it.
Of the age in which these men lived and worked, giving their all in many
cases to the science they loved, even to life itself, it may be said
with truth that 'there were giants on the earth in those days,' as far
as aeronautics is in question. It was an age of giants who lived and
dared and died, venturing into uncharted space, knowing nothing of its
dangers, giving, as a man gives to his mistress, without stint and
for the joy of the giving. The science of to-day, compared with the
glimmerings that were in that age of the giants, is a fixed and certain
thing; the problems of to-day are minor problems, for the great major
problem vanished in solution when the Wright Brothers made their first
ascent. In that age of the giants was evolved the flying man, the new
type in human species which found full expression and came to full
development in the days of the war, achieving feats of daring and
endurance which leave the commonplace landsman staggered at thought of
that of which his fellows prove themselves capable. He is a new type,
this flying man, a being of self-forgetfulness; of such was Lilienthal,
of such was Pilcher; of such in later days were Farman, Bleriot, Hamel,
Rolls, and their fellows; great names that will live for as long as man
flies, adventurers equally with those of the spacious days of Elizabeth.
To each of these came the call, and he worked and dared and passed,
having, perhaps, advanced one little step in the long march that has led
toward the perfecting of flight.
It is not yet twenty years since man first flew, but into that twenty
years have been compressed a century or so of progress, while, in the
two decades that preceded it, was compressed still more. We have only to
recall and recount the work of four men: Lilienthal, Langley, Pilcher,
and Clement Ader to see the immense stride that was made between the
time when Penaud pulled a trigger for the last time and the Wright
Brothers first left the earth. Into those two decades was compressed the
investigation that meant knowledge of the qualities of the air, together
with the development of the one prime mover that rendered flight a
possibility--the internal combustion engine. The coming and progress of
this latter is a thing apart, to be detailed separately; for the present
we are concerned with the evolution of the driven plane, and with it the
evolution of that daring being, the flying man. The two are inseparable,
for the men gave themselves to their art; the story of Lilienthal's life
and death is the story of his work; the story of Pilcher's work is that
of his life and death.
Considering the flying man as he appeared in the war period, there
entered into his composition a new element--patriotism--which brought
about a modification of the type, or, perhaps, made it appear that
certain men belonged to the type who in reality were commonplace
mortals, animated, under normal conditions, by normal motives, but
driven by the stress of the time to take rank with the last expression
of human energy, the flying type. However that may be, what may be
termed the mathematising of aeronautics has rendered the type itself
evanescent; your pilot of to-day knows his craft, once he is trained,
much in the manner that a driver of a motor-lorry knows his vehicle;
design has been systematised, capabilities have been tabulated; camber,
dihedral angle, aspect ratio, engine power, and plane surface, are
business items of drawing office and machine shop; there is room for
enterprise, for genius, and for skill; once and again there is room for
daring, as in the first Atlantic flight. Yet that again was a thing of
mathematical calculation and petrol storage, allied to a certain stark
courage which may be found even in landsmen. For the ventures into the
unknown, the limit of daring, the work for work's sake, with the almost
certainty that the final reward was death, we must look back to the age
of the giants, the age when flying was not a business, but romance.
VII. LILIENTHAL AND PILCHER
There was never a more enthusiastic and consistent student of the
problems of flight than Otto Lilienthal, who was born in 1848 at Anklam,
Pomerania, and even from his early school-days dreamed and planned the
conquest of the air. His practical experiments began when, at the age
of thirteen, he and his brother Gustav made wings consisting of wooden
framework covered with linen, which Otto attached to his arms, and then
ran downhill flapping them. In consequence of possible derision on the
part of other boys, Otto confined these experiments for the most part to
moonlit nights, and gained from them some idea of the resistance offered
by flat surfaces to the air. It was in 1867 that the two brothers
began really practical work, experimenting with wings which, from
their design, indicate some knowledge of Besnier and the history of his
gliding experiments; these wings the brothers fastened to their backs,
moving them with their legs after the fashion of one attempting to swim.
Before they had achieved any real success in gliding the Franco-German
war came as an interruption; both brothers served in this campaign,
resuming their experiments in 1871 at the conclusion of hostilities.
The experiments made by the brothers previous to the war had convinced
Otto that previous experimenters in gliding flight had failed through
reliance on empirical conclusions or else through incomplete observation
on their own part, mostly of bird flight. From 1871 onward Otto
Lilenthal (Gustav's interest in the problem was not maintained as was
his brother's) made what is probably the most detailed and accurate
series of observations that has ever been made with regard to the
properties of curved wing surfaces. So far as could be done, Lilienthal
tabulated the amount of air resistance offered to a bird's wing,
ascertaining that the curve is necessary to flight, as offering far more
resistance than a flat surface. Cayley, and others, had already stated
this, but to Lilienthal belongs the honour of being first to put the
statement to effective proof--he made over 2,000 gliding flights
between 1891 and the regrettable end of his experiments; his practical
conclusions are still regarded as part of the accepted theory of
students of flight. In 1889 he published a work on the subject of
gliding flight which stands as data for investigators, and, on the
conclusions embodied in this work, he began to build his gliders and
practice what he had preached, turning from experiment with models to
wings that he could use.
It was in the summer of 1891 that he built his first glider of rods of
peeled willow, over which was stretched strong cotton fabric; with this,
which had a supporting surface of about 100 square feet, Otto Lilienthal
launched himself in the air from a spring board, making glides which, at
first of only a few feet, gradually lengthened. As his experience of
the supporting qualities of the air progressed he gradually altered
his designs until, when Pilcher visited him in the spring of 1895,
he experimented with a glider, roughly made of peeled willow rods and
cotton fabric, having an area of 150 square feet and weighing half a
hundredweight. By this time Lilienthal had moved from his springboard to
a conical artificial hill which he had had thrown up on level ground at
Grosse Lichterfelde, near Berlin. This hill was made with earth taken
from the excavations incurred in constructing a canal, and had a cave
inside in which Lilienthal stored his machines. Pilcher, in his paper
on 'Gliding,' [*] gives an excellent short summary of Lilienthal's
experiments, from which the following extracts are taken:--
[*] Aeronautical Classes, No. 5. Royal Aeronautical Society's
publications.
'At first Lilienthal used to experiment by jumping off a springboard
with a good run. Then he took to practicing on some hills close to
Berlin. In the summer of 1892 he built a flat-roofed hut on the summit
of a hill, from the top of which he used to jump, trying, of course, to
soar as far as possible before landing.... One of the great dangers with
a soaring machine is losing forward speed, inclining the machine too
much down in front, and coming down head first. Lilienthal was the
first to introduce the system of handling a machine in the air merely
by moving his weight about in the machine; he always rested only on his
elbows or on his elbows and shoulders....
'In 1892 a canal was being cut, close to where Lilienthal lived, in the
suburbs of Berlin, and with the surplus earth Lilienthal had a special
hill thrown up to fly from. The country round is as flat as the sea, and
there is not a house or tree near it to make the wind unsteady, so
this was an ideal practicing ground; for practicing on natural hills
is generally rendered very difficult by shifty and gusty winds.... This
hill is 50 feet high, and conical. Inside the hill there is a cave for
the machines to be kept in.... When Lilienthal made a good flight he
used to land 300 feet from the centre of the hill, having come down at
an angle of 1 in 6; but his best flights have been at an angle of about
1 in 10.
'If it is calm, one must run a few steps down the hill, holding the
machine as far back on oneself as possible, when the air will gradually
support one, and one slides off the hill into the air. If there is any
wind, one should face it at starting; to try to start with a side wind
is most unpleasant. It is possible after a great deal of practice to
turn in the air, and fairly quickly. This is accomplished by throwing
one's weight to one side, and thus lowering the machine on that side
towards which one wants to turn. Birds do the same thing--crows and
gulls show it very clearly. Last year Lilienthal chiefly experimented
with double-surfaced machines. These were very much like the old
machines with awnings spread above them.
'The object of making these double-surfaced machines was to get more
surface without increasing the length and width of the machine. This,
of course, it does, but I personally object to any machine in which
the wing surface is high above the weight. I consider that it makes
the machine very difficult to handle in bad weather, as a puff of wind
striking the surface, high above one, has a great tendency to heel the
machine over.
'Herr Lilienthal kindly allowed me to sail down his hill in one of these
double-surfaced machines last June. With the great facility afforded by
his conical hill the machine was handy enough; but I am afraid I should
not be able to manage one at all in the squally districts I have had to
practice in over here.
'Herr Lilienthal came to grief through deserting his old method of
balancing. In order to control his tipping movements more rapidly he
attached a line from his horizontal rudder to his head, so that when he
moved his head forward it would lift the rudder and tip the machine up
in front, and vice versa. He was practicing this on some natural hills
outside Berlin, and he apparently got muddled with the two motions, and,
in trying to regain speed after he had, through a lull in the wind, come
to rest in the air, let the machine get too far down in front, came down
head first and was killed.'
Then in another passage Pilcher enunciates what is the true value of
such experiments as Lilienthal--and, subsequently, he himself--made:
'The object of experimenting with soaring machines,' he says, 'is to
enable one to have practice in starting and alighting and controlling a
machine in the air. They cannot possibly float horizontally in the
air for any length of time, but to keep going must necessarily lose in
elevation. They are excellent schooling machines, and that is all they
are meant to be, until power, in the shape of an engine working a screw
propeller, or an engine working wings to drive the machine forward, is
added; then a person who is used to soaring down a hill with a simple
soaring machine will be able to fly with comparative safety. One can
best compare them to bicycles having no cranks, but on which one could
learn to balance by coming down an incline.'
It was in 1895 that Lilienthal passed from experiment with the monoplane
type of glider to the construction of a biplane glider which, according
to his own account, gave better results than his previous machines.
'Six or seven metres velocity of wind,' he says, 'sufficed to enable
the sailing surface of 18 square metres to carry me almost horizontally
against the wind from the top of my hill without any starting jump. If
the wind is stronger I allow myself to be simply lifted from the point
of the hill and to sail slowly towards the wind. The direction of the
flight has, with strong wind, a strong upwards tendency. I often reach
positions in the air which are much higher than my starting point. At
the climax of such a line of flight I sometimes come to a standstill
for some time, so that I am enabled while floating to speak with the
gentlemen who wish to photograph me, regarding the best position for the
photographing.'
Lilienthal's work did not end with simple gliding, though he did not
live to achieve machine-driven flight. Having, as he considered, gained
sufficient experience with gliders, he constructed a power-driven
machine which weighed altogether about 90 lbs., and this was thoroughly
tested. The extremities of its wings were made to flap, and the driving
power was obtained from a cylinder of compressed carbonic acid gas,
released through a hand-operated valve which, Lilienthal anticipated,
would keep the machine in the air for four minutes. There were certain
minor accidents to the mechanism, which delayed the trial flights, and
on the day that Lilienthal had determined to make his trial he made a
long gliding flight with a view to testing a new form of rudder that--as
Pilcher relates--was worked by movements of his head. His death came
about through the causes that Pilcher states; he fell from a height of
50 feet, breaking his spine, and the next day he died.
It may be said that Lilienthal accomplished as much as any one of the
great pioneers of flying. As brilliant in his conceptions as da Vinci
had been in his, and as conscientious a worker as Borelli, he laid the
foundations on which Pilcher, Chanute, and Professor Montgomery were
able to build to such good purpose. His book on bird flight, published
in 1889, with the authorship credited both to Otto and his brother
Gustav, is regarded as epoch-making; his gliding experiments are no less
entitled to this description.
In England Lilienthal's work was carried on by Percy Sinclair Pilcher,
who, born in 1866, completed six years' service in the British Navy
by the time that he was nineteen, and then went through a course of
engineering, subsequently joining Maxim in his experimental work. It was
not until 1895 that he began to build the first of the series of gliders
with which he earned his plane among the pioneers of flight. Probably
the best account of Pilcher's work is that given in the Aeronautical
Classics issued by the Royal Aeronautical Society, from which the
following account of Pilcher's work is mainly abstracted.[*]
[*] Aeronautical Classes, No. 5. Royal Aeronautical Society
publications.
The 'Bat,' as Pilcher named his first glider, was a monoplane which he
completed before he paid his visit to Lilienthal in 1895. Concerning
this Pilcher stated that he purposely finished his own machine before
going to see Lilienthal, so as to get the greatest advantage from any
original ideas he might have; he was not able to make any trials with
this machine, however, until after witnessing Lilienthal's experiments
and making several glides in the biplane glider which Lilienthal
constructed.
The wings of the 'Bat' formed a pronounced dihedral angle; the tips
being raised 4 feet above the body. The spars forming the entering
edges of the wings crossed each other in the centre and were lashed to
opposite sides of the triangle that served as a mast for the stay-wires
that guyed the wings. The four ribs of each wing, enclosed in pockets
in the fabric, radiated fanwise from the centre, and were each stayed by
three steel piano-wires to the top of the triangular mast, and similarly
to its base. These ribs were bolted down to the triangle at their roots,
and could be easily folded back on to the body when the glider was not
in use. A small fixed vertical surface was carried in the rear. The
framework and ribs were made entirely of Riga pine; the surface fabric
was nainsook. The area of the machine was 150 square feet; its weight
45 lbs.; so that in flight, with Pilcher's weight of 145 lbs. added, it
carried one and a half pounds to the square foot.
Pilcher's first glides, which he carried out on a grass hill on the
banks of the Clyde near Cardross, gave little result, owing to the
exaggerated dihedral angle of the wings, and the absence of a horizontal
tail. The 'Bat 'was consequently reconstructed with a horizontal tail
plane added to the vertical one, and with the wings lowered so that the
tips were only six inches above the level of the body. The machine now
gave far better results; on the first glide into a head wind Pilcher
rose to a height of twelve feet and remained in the the air for a third
of a minute; in the second attempt a rope was used to tow the glider,
which rose to twenty feet and did not come to earth again until nearly
a minute had passed. With experience Pilcher was able to lengthen his
glide and improve his balance, but the dropped wing tips made landing
difficult, and there were many breakages.
In consequence of this Pilcher built a second glider which he named
the 'Beetle,' because, as he said, it looked like one. In this the
square-cut wings formed almost a continuous plane, rigidly fixed to the
central body, which consisted of a shaped girder. These wings were built
up of five transverse bamboo spars, with two shaped ribs running from
fore to aft of each wing, and were stayed overhead to a couple of masts.
The tail, consisting of two discs placed crosswise (the horizontal
one alone being movable), was carried high up in the rear. With the
exception of the wing-spars, the whole framework was built of white
pine. The wings in this machine were actually on a higher level than the
operator's head; the centre of gravity was, consequently, very low, a
fact which, according to Pilcher's own account, made the glider very
difficult to handle. Moreover, the weight of the 'Beetle,' 80 lbs., was
considerable; the body had been very solidly built to enable it to carry
the engine which Pilcher was then contemplating; so that the glider
carried some 225 lbs. with its area of 170 square feet--too great a mass
for a single man to handle with comfort.
It was in the spring of 1896 that Pilcher built his third glider, the
'Gull,' with 300 square feet of area and a weight of 55 lbs. The size of
this machine rendered it unsuitable for experiment in any but very calm
weather, and it incurred such damage when experiments were made in a
breeze that Pilcher found it necessary to build a fourth, which he named
the 'Hawk.' This machine was very soundly built, being constructed of
bamboo, with the exception of the two main transverse beams. The wings
were attached to two vertical masts, 7 feet high, and 8 feet apart,
joined at their summits and their centres by two wooden beams. Each wing
had nine bamboo ribs, radiating from its mast, which was situated at a
distance of 2 feet 6 inches from the forward edge of the wing. Each rib
was rigidly stayed at the top of the mast by three tie-wires, and by a
similar number to the bottom of the mast, by which means the curve of
each wing was maintained uniformly. The tail was formed of a triangular
horizontal surface to which was affixed a triangular vertical surface,
and was carried from the body on a high bamboo mast, which was also
stayed from the masts by means of steel wires, but only on its upper
surface, and it was the snapping of one of these guy wires which caused
the collapse of the tail support and brought about the fatal end of
Pilcher's experiments. In flight, Pilcher's head, shoulders, and the
greater part of his chest projected above the wings. He took up his
position by passing his head and shoulders through the top aperture
formed between the two wings, and resting his forearms on the
longitudinal body members. A very simple form of undercarriage, which
took the weight off the glider on the ground, was fitted, consisting of
two bamboo rods with wheels suspended on steel springs.
Balance and steering were effected, apart from the high degree of
inherent stability afforded by the tail, as in the case of Lilienthal's
glider, by altering the position of the body. With this machine Pilcher
made some twelve glides at Eynsford in Kent in the summer of 1896, and
as he progressed he increased the length of his glides, and also handled
the machine more easily, both in the air and in landing. He was occupied
with plans for fitting an engine and propeller to the 'Hawk,' but, in
these early days of the internal combustion engine, was unable to
get one light enough for his purpose. There were rumours of an engine
weighing 15 lbs. which gave 1 horse-power, and was reported to be in
existence in America, but it could not be traced.
In the spring of 1897 Pilcher took up his gliding experiments again,
obtaining what was probably the best of his glides on June 19th, when he
alighted after a perfectly balanced glide of over 250 yards in length,
having crossed a valley at a considerable height. From his various
experiments he concluded that once the machine was launched in the air
an engine of, at most, 3 horse-power would suffice for the maintenance
of horizontal flight, but he had to allow for the additional weight
of the engine and propeller, and taking into account the comparative
inefficiency of the propeller, he planned for an engine of 4
horse-power. Engine and propeller together were estimated at under 44
lbs. weight, the engine was to be fitted in front of the operator, and
by means of an overhead shaft was to operate the propeller situated
in rear of the wings. 1898 went by while this engine was under
construction. Then in 1899 Pilcher became interested in Lawrence
Hargrave's soaring kites, with which he carried out experiments during
the summer of 1899. It is believed that he intended to incorporate
a number of these kites in a new machine, a triplane, of which the
fragments remaining are hardly sufficient to reconstitute the complete
glider. This new machine was never given a trial. For on September 30th,
1899, at Stamford Hall, Market Harborough, Pilcher agreed to give a
demonstration of gliding flight, but owing to the unfavourable weather
he decided to postpone the trial of the new machine and to experiment
with the 'Hawk,' which was intended to rise from a level field, towed by
a line passing over a tackle drawn by two horses. At the first trial the
machine rose easily, but the tow-line snapped when it was well clear of
the ground, and the glider descended, weighed down through being sodden
with rain. Pilcher resolved on a second trial, in which the glider again
rose easily to about thirty feet, when one of the guy wires of the tail
broke, and the tail collapsed; the machine fell to the ground, turning
over, and Pilcher was unconscious when he was freed from the wreckage.
Hopes were entertained of his recovery, but he died on Monday, October
2nd, 1899, aged only thirty-four. His work in the cause of flying
lasted only four years, but in that time his actual accomplishments were
sufficient to place his name beside that of Lilienthal, with whom he
ranks as one of the greatest exponents of gliding flight.
VIII. AMERICAN GLIDING EXPERIMENTS
While Pilcher was carrying on Lilienthal's work in England, the great
German had also a follower in America; one Octave Chanute, who, in one
of the statements which he has left on the subject of his experiments
acknowledges forty years' interest in the problem of flight, did more
to develop the glider in America than--with the possible exception
of Montgomery--any other man. Chanute had all the practicality of an
American; he began his work, so far as actual gliding was concerned,
with a full-sized glider of the Lilienthal type, just before Lilienthal
was killed. In a rather rare monograph, entitled Experiments in Flying,
Chanute states that he found the Lilienthal glider hazardous and decided
to test the value of an idea of his own; in this he followed the same
general method, but reversed the principle upon which Lilienthal had
depended for maintaining his equilibrium in the air. Lilienthal had
shifted the weight of his body, under immovable wings, as fast and as
far as the sustaining pressure varied under his surfaces; this shifting
was mainly done by moving the feet, as the actions required were small
except when alighting. Chanute's idea was to have the operator remain
seated in the machine in the air, and to intervene only to steer or to
alight; moving mechanism was provided to adjust the wings automatically
in order to restore balance when necessary.
Chanute realised that experiments with models were of little use; in
order to be fully instructive, these experiments should be made with
a full-sized machine which carried its operator, for models seldom fly
twice alike in the open air, and no relation can be gained from them of
the divergent air currents which they have experienced. Chanute's idea
was that any flying machine which might be constructed must be able to
operate in a wind; hence the necessity for an operator to report upon
what occurred in flight, and to acquire practical experience of the work
of the human factor in imitation of bird flight. From this point of
view he conducted his own experiments; it must be noted that he was
over sixty years of age when he began, and, being no longer sufficiently
young and active to perform any but short and insignificant glides, the
courage of the man becomes all the more noteworthy; he set to work to
evolve the state required by the problem of stability, and without any
expectation of advancing to the construction of a flying machine which
might be of commercial value. His main idea was the testing of devices
to secure equilibrium; for this purpose he employed assistants to
carry out the practical work, where he himself was unable to supply the
necessary physical energy.
Together with his assistants he found a suitable place for experiments
among the sandhills on the shore of Lake Michigan, about thirty miles
eastward from Chicago. Here a hill about ninety-five feet high was
selected as a point from which Chanute's gliders could set off; in
practice, it was found that the best observation was to be obtained
from short glides at low speed, and, consequently, a hill which was
only sixty-one feet above the shore of the lake was employed for the
experimental work done by the party.
In the years 1896 and 1897, with parties of from four to six persons,
five full-sized gliders were tried out, and from these two distinct
types were evolved: of these one was a machine consisting of five tiers
of wings and a steering tail, and the other was of the biplane type;
Chanute believed these to be safer than any other machine previously
evolved, solving, as he states in his monograph, the problem of inherent
equilibrium as fully as this could be done. Unfortunately, very few
photographs were taken of the work in the first year, but one view of a
multiple wing-glider survives, showing the machine in flight. In 1897 a
series of photographs was taken exhibiting the consecutive phases of
a single flight; this series of photographs represents the experience
gained in a total of about one thousand glides, but the point of view
was varied so as to exhibit the consecutive phases of one single flight.
The experience gained is best told in Chanute's own words. 'The first
thing,' he says, 'which we discovered practically was that the wind
flowing up a hill-side is not a steadily-flowing current like that of a
river. It comes as a rolling mass, full of tumultuous whirls and eddies,
like those issuing from a chimney; and they strike the apparatus with
constantly varying force and direction, sometimes withdrawing support
when most needed. It has long been known, through instrumental
observations, that the wind is constantly changing in force and
direction; but it needed the experience of an operator afloat on a
gliding machine to realise that this all proceeded from cyclonic action;
so that more was learned in this respect in a week than had previously
been acquired by several years of experiments with models. There was a
pair of eagles, living in the top of a dead tree about two miles from
our tent, that came almost daily to show us how such wind effects are
overcome and utilised. The birds swept in circles overhead on
pulseless wings, and rose high up in the air. Occasionally there was
a side-rocking motion, as of a ship rolling at sea, and then the birds
rocked back to an even keel; but although we thought the action was
clearly automatic, and were willing to learn, our teachers were too
far off to show us just how it was done, and we had to experiment for
ourselves.'
Chanute provided his multiple glider with a seat, but, since each
glide only occupied between eight and twelve seconds, there was little
possibility of the operator seating himself. With the multiple glider a
pair of horizontal bars provided rest for the arms, and beyond these
was a pair of vertical bars which the operator grasped with his hands;
beyond this, the operator was in no way attached to the machine. He
took, at the most, four running steps into the wind, which launched
him in the air, and thereupon he sailed into the wind on a generally
descending course. In the matter of descent Chanute observed the sparrow
and decided to imitate it. 'When the latter,' he says, 'approaches the
street, he throws his body back, tilts his outspread wings nearly square
to the course, and on the cushion of air thus encountered he stops his
speed and drops lightly to the ground. So do all birds. We tried it with
misgivings, but found it perfectly effective. The soft sand was a great
advantage, and even when the experts were racing there was not a single
sprained ankle.'
With the multiple winged glider some two to three hundred glides were
made without any accident either to the man or to the machine, and the
action was found so effective, the principle so sound, that full plans
were published for the benefit of any experimenters who might wish to
improve on this apparatus. The American Aeronautical Annual for 1897
contains these plans; Chanute confessed that some movement on the part
of the operator was still required to control the machine, but it was
only a seventh or a sixth part of the movement required for control of
the Lilienthal type.
Chanute waxed enthusiastic over the possibilities of gliding, concerning
which he remarks that 'There is no more delightful sensation than that
of gliding through the air. All the faculties are on the alert, and
the motion is astonishingly smooth and elastic. The machine responds
instantly to the slightest movement of the operator; the air rushes by
one's ears; the trees and bushes flit away underneath, and the landing
comes all too quickly. Skating, sliding, and bicycling are not to be
compared for a moment to aerial conveyance, in which, perhaps, zest is
added by the spice of danger. For it must be distinctly understood that
there is constant danger in such preliminary experiments. When this
hazard has been eliminated by further evolution, gliding will become a
most popular sport.'
Later experiments proved that the biplane type of glider gave better
results than the rather cumbrous model consisting of five tiers of
planes. Longer and more numerous glides, to the number of seven to eight
hundred, were obtained, the rate of descent being about one in six. The
longest distance traversed was about 120 yards, but Chanute had dreams
of starting from a hill about 200 feet high, which would have given him
gliding flights of 1,200 feet. He remarked that 'In consequence of
the speed gained by running, the initial stage of the flight is nearly
horizontal, and it is thrilling to see the operator pass from thirty to
forty feet overhead, steering his machine, undulating his course, and
struggling with the wind-gusts which whistle through the guy wires. The
automatic mechanism restores the angle of advance when compromised by
variations of the breeze; but when these come from one side and tilt the
apparatus, the weight has to be shifted to right the machine... these
gusts sometimes raise the machine from ten to twenty feet vertically,
and sometimes they strike the apparatus from above, causing it to
descend suddenly. When sailing near the ground, these vicissitudes can
be counteracted by movements of the body from three to four inches; but
this has to be done instantly, for neither wings nor gravity will wait
on meditation. At a height of three hundred or four hundred feet the
regulating mechanism would probably take care of these wind-gusts, as it
does, in fact, for their minor variations. The speed of the machine
is generally about seventeen miles an hour over the ground, and from
twenty-two to thirty miles an hour relative to the air. Constant effort
was directed to keep down the velocity, which was at times fifty-two
miles an hour. This is the purpose of the starting and gliding against
the wind, which thus furnishes an initial velocity without there being
undue speed at the landing. The highest wind we dared to experiment in
blew at thirty-one miles an hour; when the wind was stronger, we waited
and watched the birds.'
Chanute details an amusing little incident which occurred in the course
of experiment with the biplane glider. He says that 'We had taken one
of the machines to the top of the hill, and loaded its lower wings with
sand to hold it while we e went to lunch. A gull came strolling inland,
and flapped full-winged to inspect. He swept several circles above the
machine, stretched his neck, gave a squawk and went off. Presently he
returned with eleven other gulls, and they seemed to hold a conclave
about one hundred feet above the big new white bird which they had
discovered on the sand. They circled round after round, and once in a
while there was a series of loud peeps, like those of a rusty gate, as
if in conference, with sudden flutterings, as if a terrifying suggestion
had been made. The bolder birds occasionally swooped downwards to
inspect the monster more closely; they twisted their heads around to
bring first one eye and then the other to bear, and then they rose
again. After some seven or eight minutes of this performance, they
evidently concluded either that the stranger was too formidable to
tackle, if alive, or that he was not good to eat, if dead, and they flew
off to resume fishing, for the weak point about a bird is his stomach.'
The gliders were found so stable, more especially the biplane form, that
in the end Chanute permitted amateurs to make trials under guidance,
and throughout the whole series of experiments not a single accident
occurred. Chanute came to the conclusion that any young, quick, and
handy man could master a gliding machine almost as soon as he could get
the hang of a bicycle, although the penalty for any mistake would be
much more severe.
At the conclusion of his experiments he decided that neither the
multiple plane nor the biplane type of glider was sufficiently perfected
for the application of motive power. In spite of the amount of automatic
stability that he had obtained he considered that there was yet more to
be done, and he therefore advised that every possible method of securing
stability and safety should be tested, first with models, and then with
full-sized machines; designers, he said, should make a point of practice
in order to make sure of the action, to proportion and adjust the parts
of their machine, and to eliminate hidden defects. Experimental
flight, he suggested, should be tried over water, in order to break any
accidental fall; when a series of experiments had proved the stability
of a glider, it would then be time to apply motive power. He admitted
that such a process would be both costly and slow, but, he said, that
'it greatly diminished the chance of those accidents which bring a whole
line of investigation into contempt.' He saw the flying machine as what
it has, in fact, been; a child of evolution, carried on step by step
by one investigator after another, through the stages of doubt and
perplexity which lie behind the realm of possibility, beyond which is
the present day stage of actual performance and promise of ultimate
success and triumph over the earlier, more cumbrous, and slower forms of
the transport that we know.
Chanute's monograph, from which the foregoing notes have been comprised,
was written soon after the conclusion of his series of experiments. He
does not appear to have gone in for further practical work, but to
have studied the subject from a theoretical view-point and with great
attention to the work done by others. In a paper contributed in 1900
to the American Independent, he remarks that 'Flying machines promise
better results as to speed, but yet will be of limited commercial
application. They may carry mails and reach other inaccessible places,
but they cannot compete with railroads as carriers of passengers or
freight. They will not fill the heavens with commerce, abolish custom
houses, or revolutionise the world, for they will be expensive for
the loads which they can carry, and subject to too many weather
contingencies. Success is, however, probable. Each experimenter has
added something to previous knowledge which his successors can avail of.
It now seems likely that two forms of flying machines, a sporting type
and an exploration type, will be gradually evolved within one or two
generations, but the evolution will be costly and slow, and must be
carried on by well-equipped and thoroughly informed scientific men; for
the casual inventor, who relies upon one or two happy inspirations, will
have no chance of success whatever.'
Follows Professor John J. Montgomery, who, in the true American spirit,
describes his own experiments so well that nobody can possibly do it
better. His account of his work was given first of all in the American
Journal, Aeronautics, in January, 1909, and thence transcribed in the
English paper of the same name in May, 1910, and that account is here
copied word for word. It may, however, be noted first that as far back
as 1860, when Montgomery was only a boy, he was attracted to the study
of aeronautical problems, and in 1883 he built his first machine,
which was of the flapping-wing ornithopter type, and which showed its
designer, with only one experiment, that he must design some other
form of machine if he wished to attain to a successful flight.
Chanute details how, in 1884 and 1885 Montgomery built three gliders,
demonstrating the value of curved surfaces. With the first of these
gliders Montgomery copied the wing of a seagull; with the second he
proved that a flat surface was virtually useless, and with the third
he pivoted his wings as in the Antoinette type of power-propelled
aeroplane, proving to his own satisfaction that success lay in this
direction. His own account of the gliding flights carried out under his
direction is here set forth, being the best description of his work that
can be obtained:--
'When I commenced practical demonstration in my work with aeroplanes
I had before me three points; first, equilibrium; second, complete
control; and third, long continued or soaring flight. In starting I
constructed and tested three sets of models, each in advance of the
other in regard to the continuance of their soaring powers, but all
equally perfect as to equilibrium and control. These models were tested
by dropping them from a cable stretched between two mountain tops, with
various loads, adjustments and positions. And it made no difference
whether the models were dropped upside down or any other conceivable
position, they always found their equilibrium immediately and glided
safely to earth.
'Then I constructed a large machine patterned after the first model, and
with the assistance of three cowboy friends personally made a number of
flights in the steep mountains near San Juan (a hundred miles distant).
In making these flights I simply took the aeroplane and made a running
jump. These tests were discontinued after I put my foot into a squirrel
hole in landing and hurt my leg.
'The following year I commenced the work on a larger scale, by engaging
aeronauts to ride my aeroplane dropped from balloons. During this work I
used five hot-air balloons and one gas balloon, five or six aeroplanes,
three riders--Maloney, Wilkie, and Defolco--and had sixteen applicants
on my list, and had a training station to prepare any when I needed
them.
'Exhibitions were given in Santa Cruz, San Jose, Santa Clara, Oaklands,
and Sacramento. The flights that were made, instead of being haphazard
affairs, were in the order of safety and development. In the first
flight of an aeronaut the aeroplane was so arranged that the rider had
little liberty of action, consequently he could make only a limited
flight. In some of the first flights, the aeroplane did little more than
settle in the air. But as the rider gained experience in each successive
flight I changed the adjustments, giving him more liberty of action, so
he could obtain longer flights and more varied movements in the flights.
But in none of the flights did I have the adjustments so that the riders
had full liberty, as I did not consider that they had the requisite
knowledge and experience necessary for their safety; and hence, none
of my aeroplanes were launched so arranged that the rider could make
adjustments necessary for a full flight.
'This line of action caused a good deal of trouble with aeronauts or
riders, who had unbounded confidence and wanted to make long flights
after the first few trials; but I found it necessary, as they seemed
slow in comprehending the important elements and were willing to
take risks. To give them the full knowledge in these matters I was
formulating plans for a large starting station on the Mount Hamilton
Range from which I could launch an aeroplane capable of carrying two,
one of my aeronauts and myself, so I could teach him by demonstration.
But the disasters consequent on the great earthquake completely stopped
all my work on these lines. The flights that were given were only the
first of the series with aeroplanes patterned after the first model.
There were no aeroplanes constructed according to the two other models,
as I had not given the full demonstration of the workings of the first,
though some remarkable and startling work was done. On one occasion
Maloney, in trying to make a very short turn in rapid flight, pressed
very hard on the stirrup which gives a screw-shape to the wings, and
made a side somersault. The course of the machine was very much like one
turn of a corkscrew. After this movement the machine continued on its
regular course. And afterwards Wilkie, not to be outdone by Maloney,
told his friends he would do the same, and in a subsequent flight made
two side somersaults, one in one direction and the other in an opposite,
then made a deep dive and a long glide, and, when about three hundred
feet in the air, brought the aeroplane to a sudden stop and settled to
the earth. After these antics, I decreased the extent of the possible
change in the form of wing-surface, so as to allow only straight sailing
or only long curves in turning.
'During my work I had a few carping critics that I silenced by this
standing offer: If they would deposit a thousand dollars I would cover
it on this proposition. I would fasten a 150 pound sack of sand in the
rider's seat, make the necessary adjustments, and send up an aeroplane
upside down with a balloon, the aeroplane to be liberated by a time
fuse. If the aeroplane did not immediately right itself, make a flight,
and come safely to the ground, the money was theirs.
'Now a word in regard to the fatal accident. The circumstances are
these: The ascension was given to entertain a military company in which
were many of Maloney's friends, and he had told them he would give the
most sensational flight they ever heard of. As the balloon was rising
with the aeroplane, a guy rope dropping switched around the right wing
and broke the tower that braced the two rear wings and which also gave
control over the tail. We shouted Maloney that the machine was broken,
but he probably did not hear us, as he was at the same time saying,
"Hurrah for Montgomery's airship," and as the break was behind him, he
may not have detected it. Now did he know of the breakage or not, and if
he knew of it did he take a risk so as not to disappoint his friends?
At all events, when the machine started on its flight the rear wings
commenced to flap (thus indicating they were loose), the machine turned
on its back, and settled a little faster than a parachute. When we
reached Maloney he was unconscious and lived only thirty minutes. The
only mark of any kind on him was a scratch from a wire on the side of
his neck. The six attending physicians were puzzled at the cause of his
death. This is remarkable for a vertical descent of over 2,000 feet.'
The flights were brought to an end by the San Francisco earthquake in
April, 1906, which, Montgomery states, 'Wrought such a disaster that I
had to turn my attention to other subjects and let the aeroplane rest
for a time.' Montgomery resumed experiments in 1911 in California, and
in October of that year an accident brought his work to an end. The
report in the American Aeronautics says that 'a little whirlwind caught
the machine and dashed it head on to the ground; Professor Montgomery
landed on his head and right hip. He did not believe himself seriously
hurt, and talked with his year-old bride in the tent. He complained of
pains in his back, and continued to grow worse until he died.'
IX. NOT PROVEN
The early history of flying, like that of most sciences, is replete
with tragedies; in addition to these it contains one mystery concerning
Clement Ader, who was well known among European pioneers in the
development of the telephone, and first turned his attention to the
problems of mechanical flight in 1872. At the outset he favoured the
ornithopter principle, constructing a machine in the form of a bird with
a wing-spread of twenty-six feet; this, according to Ader's conception,
was to fly through the efforts of the operator. The result of such
an attempt was past question and naturally the machine never left the
ground.
A pause of nineteen years ensued, and then in 1886 Ader turned his mind
to the development of the aeroplane, constructing a machine of bat-like
form with a wingspread of about forty-six feet, a weight of eleven
hundred pounds, and a steam-power plant of between twenty and thirty
horse-power driving a four-bladed tractor screw. On October 9th, 1890,
the first trials of this machine were made, and it was alleged to have
flown a distance of one hundred and sixty-four feet. Whatever truth
there may be in the allegation, the machine was wrecked through
deficient equilibrium at the end of the trial. Ader repeated the
construction, and on October 14th, 1897, tried out his third machine
at the military establishment at Satory in the presence of the French
military authorities, on a circular track specially prepared for the
experiment. Ader and his friends alleged that a flight of nearly a
thousand feet was made; again the machine was wrecked at the end of the
trial, and there Ader's practical work may be said to have ended, since
no more funds were forthcoming for the subsidy of experiments.
There is the bald narrative, but it is worthy of some amplification. If
Ader actually did what he claimed, then the position which the Wright
Brothers hold as first to navigate the
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