the mastery of the air(操纵空气)-第13节
按键盘上方向键 ← 或 → 可快速上下翻页，按键盘上的 Enter 键可回到本书目录页，按键盘上方向键 ↑ 可回到本页顶部！
————未阅读完？加入书签已便下次继续阅读！
the very foundation…stones of inventionif we may be allowed the figure
of speechand Englishmen are proud； and rightly proud； to number within
their ranks the original inventor of the heavier…than…air machine。
49
… Page 50…
THE MASTERY OF THE AIR
50
… Page 51…
THE MASTERY OF THE AIR
CHAPTER XVI The 〃Human Birds〃
For many years after the publication of Sir George Cayley's articles
and lectures on aviation very little was done in the way of aerial
experiments。 True； about midway through the nineteenth century two
clever engineers； Henson and Stringfellow； built a model aeroplane after
the design outlined by Sir George； but though their model was not of
much practical value； a little more valuable experience was accumulated
which would be of service when the time should come； in other words；
when the motor engine should arrive。 This model can be seen at the
Victoria and Albert Museum； at South Kensington。
A few years later Stringfellow designed a tiny steam…engine； which he
fitted to an equally tiny monoplane； and it is said that by its aid he was
able to obtain a very short flight through the air。 As some recognition of
his enterprise the Aeronautical Society； which was founded in 1866；
awarded him a prize of L100 for his engine。
The idea of producing a practical form of flying machine was never
abandoned entirely。 Here and there experiments continued to be carried
out； and certain valuable conclusions were arrived at。 Many advanced
thinkers and writers of half a century ago set forth their opinions on the
possibilities of human flight。 Some of them； like Emerson； not only
believed that flight would come； but also stated why it had not arrived。
Thus Emerson； when writing on the subject of air navigation about fifty
years ago； remarked： 〃We think the population is not yet quite fit for them；
and therefore there will be none。 Our friend suggests so many
inconveniences from piracy out of the high air to orchards and lone houses；
and also to high fliers； and the total inadequacy of the present system of
defence； that we have not the heart to break the sleep of the great public by
the repetition of these details。 When children come into the library we put
the inkstand and the watch on the high shelf until they be a little older。〃
About the year 1870 a young German engineer； named Otto Lilienthal；
began some experiments with a motorless glider； which in course of time
were to make him world…famed。 For nearly twenty years Lilienthal carried
on his aerial research work in secrecy； and it was not until about the year
51
… Page 52…
THE MASTERY OF THE AIR
1890 that his experimental work was sufficiently advanced for him to give
demonstrations in public。
The young German was a firm believer in what was known as the
〃soaring…plane〃 theory of flight。 From the picture here given we can get
some idea of his curious machine。 It consisted of large wings； formed of
thin osiers； over which was stretched light fabric。 At the back were two
horizontal rudders shaped somewhat like the long forked tail of a swallow；
and over these was a large steering rudder。 The wings were arranged
around the glider's body。 The whole apparatus weighed about 40 pounds。
Lilienthal's flights； or glides； were made from the top of a specially…
constructed large mound； and in some cases from the summit of a low
tower。 The 〃birdman〃 would stand on the top of the mound； full to the
wind； and run quickly forward with outstretched wings。 When he thought
he had gained sufficient momentum he jumped into the air； and the wings
of the glider bore him through the air to the base of the mound。
To preserve the balance of his machinealways a most difficult feat
he swung his legs and hips to one side or the other； as occasion required；
and； after hundreds of glides had been made； he became so skilful in
maintaining the equilibrium of his machine that he was able to cover a
distance； downhill； of 300 yards。
Later on； Lilienthal abandoned the glider； or elementary form of
monoplane； and adopted a system of superposed planes； corresponding to
the modern biplane。 The promising career of this clever German was
brought to an untimely end in 1896； when； in attempting to glide from a
height of about 80 yards； his apparatus made a sudden downward swoop；
and he broke his neck。
Now that Lillenthal's experiments had proved conclusively the
efficiency of wings； or planes； as carrying surfaces； other engineers
followed in his footsteps； and tried to improve on his good work。 The first
〃birdman〃 to use a glider in this country was Mr。 Percy Pilcher who
carried out his experiments at Cardross in Scotland。 His glides were at first
made with a form of apparatus very similar to that employed by Lilienthal；
and in time he came to use much larger machines。 So cumbersome；
however； was his apparatusit weighed nearly 4 stonesthat with such a
52
… Page 53…
THE MASTERY OF THE AIR
great weight upon his shoulders he could not run forward quickly enough
to gain sufficient momentum to 〃carry off〃 from the hillside。 To assist him
in launching the apparatus the machine was towed by horses； and when
sufficient impetus had been gained the tow…rope was cast off。
Three years after Lilienthal's death Pilcher met with a similar accident。
While making a flight his glider was overturned； and the unfortunate
〃birdman 〃 was dashed to death。
In America there were at this time two or three 〃human birds〃； one of
the most famous being M。 Octave Chanute。 During the years 1895…7
Chanute made many flights in various types of gliding machines； some of
which had as many as half a dozen planes arranged one above another。 His
best results； however； were obtained by the two…plane machine；
resembling to a remarkable extent the modern biplane。
53
… Page 54…
THE MASTERY OF THE AIR
CHAPTER XVII The Aeroplane and the Bird
We have seen that the inventors of flying machines in the early days of
aviation modelled their various craft somewhat in the form of a bird； and
that many of them believed that if the conquest of the air was to be
achieved man must copy nature and provide himself with wings。
Let us closely examine a modern monoplane and discover in what way
it resembles the body of a bird in build。
First； there is the long and comparatively narrow body； or FUSELAGE；
at the end of which is the rudder； corresponding to the bird's tail。 The
chassis； or under carriage； consisting of wheels； skids； &c。； may well be
compared with the legs of a bird； and the planes are very similar in
construction to the bird's wings。 But here the resemblance ends： the
aeroplane does not fly； nor will it ever fly； as a bird flies。
If we carefully inspect the wing of a birdsay a large bird； such as the
crowwe shall find it curved or arched from front to back。 This curve；
however； is somewhat irregular。 At the front edge of the wing it is sharpest；
and there is a gradual dip or slope backwards and downwards。 There is a
special reason for this peculiar structure； as we shall see in a later chapter。
Now it is quite evident that the inventors of aeroplanes have
modelled the planes of their craft on the bird's wing。 Strictly speaking； the
word 〃plane〃 is a misnomer when applied to the supporting structure of an
aeroplane。 Euclid defines a plane； or a plane surface； as one in which； any
two points being taken； the straight line between them lies wholly in that
surface。 But the plane of a flying machine is curved； or CAMBERED； and
if one point were taken on the front of t
